Name: cell cycle-specific measurement of &#947;h2ax and apoptosis after genotoxic stress by flow cytometry
Uploaded: 2019-09-01T14:00:00
Description: Watch this Scientific Journal Video about Cell Cycle-specific Measurement of Î³H2AX and Apoptosis After Genotoxic Stress by Flow Cytometry at JoVE.com

We thank the Flow Cytometry Facility team at the German Cancer Research Center (DKFZ) for their support.

1. Preparation
<ol>
	<li>Prepare &#8805;1 x 105 cells/sample in any type of culture vessel as starting material.
	<ol>
		<li>For example, conduct a time-course experiment after exposure of U87 glioblastoma cells to ionizing radiation: Irradiate sub-confluent U87 cells in T25 flasks in triplicates for each time point. Choose early time-points (15 min up to 8 h after irradiation) to follow the kinetics of DSB repair (&#947;H2AX level) and late time points (24 h up to 96 h) to assess residual D...

<ol>
	<li>Jensen, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+non-small+cell+lung+cancer+with+intensity-modulated+radiation+therapy+in+combination+with+cetuximab:+the+NEAR+protocol+(NCT00115518).">Treatment of non-small cell lung cancer with intensity-modulated radiation therapy in combination with cetuximab: the NEAR protocol (NCT00115518).</a> BMC Cancer. 6, 122 (2006).</li><li>Oertel, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+Glioblastoma+and+Carcinoma+Xenograft+Tumors+Treated+by+Combined+Radiation+and+Imatinib+(Gleevec).">Human Glioblastoma and Carcinoma Xenograft Tumors Treated by Combined Radiation and Imatinib (Gleevec).</a> Strahlentherapie und Onkologie. 182 (7), 400-407 (2006).</li><li>Timke, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combination+of+Vascular+Endothelial+Growth+Factor+Receptor/Platelet-Derived+Growth+Factor+Receptor+Inhibition+Markedly+Improves+Radiation+Tumor+Therapy.">Combination of Vascular Endothelial Growth Factor Receptor/Platelet-Derived Growth Factor Receptor Inhibition Markedly Improves Radiation Tumor Therapy.</a> Clinical Cancer Research. 14 (7), 2210-2219 (2008).</li><li>Zhang, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trimodal+glioblastoma+treatment+consisting+of+concurrent+radiotherapy,+temozolomide,+and+the+novel+TGF-&#946;+receptor+I+kinase+inhibitor+LY2109761.">Trimodal glioblastoma treatment consisting of concurrent radiotherapy, temozolomide, and the novel TGF-&#946; receptor I kinase inhibitor LY2109761.</a> Neoplasia. 13 (6), 537-549 (2011).</li><li>Blattmann, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suberoylanilide+hydroxamic+acid+affects+expression+in+osteosarcoma,+atypical+teratoid+rhabdoid+tumor+and+normal+tissue+cell+lines+after+irradiation.">Suberoylanilide hydroxamic acid affects expression in osteosarcoma, atypical teratoid rhabdoid tumor and normal tissue cell lines after irradiation.</a> Strahlentherapie und Onkologie. 188 (2), 168-176 (2012).</li><li>Hoeijmakers, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+Damage,+Aging,+and+Cancer.">DNA Damage, Aging, and Cancer.</a> New England Journal of Medicine. 361 (15), 1475-1485 (2015).</li><li>Rodgers, K., McVey, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Error-Prone+Repair+of+DNA+Double-Strand+Breaks.">Error-Prone Repair of DNA Double-Strand Breaks.</a> Journal of Cellular Physiology. 231 (1), 15-24 (2016).</li><li>Ciccia, A., Elledge, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+DNA+Damage+Response:+Making+It+Safe+to+Play+with+Knives.">The DNA Damage Response: Making It Safe to Play with Knives.</a> Molecular Cell. 40 (2), 179-204 (2010).</li><li>Rothkamm, K., Kr&#252;ger, I., Thompson, L. H., L&#246;brich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathways+of+DNA+double-strand+break+repair+during+the+mammalian+cell+cycle.">Pathways of DNA double-strand break repair during the mammalian cell cycle.</a> Molecular and Cellular Biology. 23 (16), 5706-5715 (2003).</li><li>Escribano-D&#237;az, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Cell+Cycle-Dependent+Regulatory+Circuit+Composed+of+53BP1-RIF1+and+BRCA1-CtIP+Controls+DNA+Repair+Pathway+Choice.">A Cell Cycle-Dependent Regulatory Circuit Composed of 53BP1-RIF1 and BRCA1-CtIP Controls DNA Repair Pathway Choice.</a> Molecular Cell. 49 (5), 872-883 (2013).</li><li>Bakr, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+crosstalk+between+DNA+damage+response+proteins+53BP1+and+BRCA1+regulates+double+strand+break+repair+choice.">Functional crosstalk between DNA damage response proteins 53BP1 and BRCA1 regulates double strand break repair choice.</a> Radiotherapy and Oncology. 119 (2), 276-281 (2015).</li><li>Mladenov, E., Magin, S., Soni, A., Iliakis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+double-strand-break+repair+in+higher+eukaryotes+and+its+role+in+genomic+instability+and+cancer:+Cell+cycle+and+proliferation-dependent+regulation.">DNA double-strand-break repair in higher eukaryotes and its role in genomic instability and cancer: Cell cycle and proliferation-dependent regulation.</a> Seminars in Cancer Biology. 37-38, 51-64 (2016).</li><li>Lopez Perez, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+damage+response+of+clinical+carbon+ion+versus+photon+radiation+in+human+glioblastoma+cells.">DNA damage response of clinical carbon ion versus photon radiation in human glioblastoma cells.</a> Radiotherapy and Oncology. 133, 77-86 (2019).</li><li>Oertel, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combination+of+suberoylanilide+hydroxamic+acid+with+heavy+ion+therapy+shows+promising+effects+in+infantile+sarcoma+cell+lines.">Combination of suberoylanilide hydroxamic acid with heavy ion therapy shows promising effects in infantile sarcoma cell lines.</a> Radiation oncology. 6 (1), 119 (2011).</li><li>Blattmann, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suberoylanilide+hydroxamic+acid+affects+&#947;H2AX+expression+in+osteosarcoma,+atypical+teratoid+rhabdoid+tumor+and+normal+tissue+cell+lines+after+irradiation.">Suberoylanilide hydroxamic acid affects &#947;H2AX expression in osteosarcoma, atypical teratoid rhabdoid tumor and normal tissue cell lines after irradiation.</a> Strahlentherapie und Onkologie. 188 (2), 168-176 (2012).</li><li>Thiemann, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+efficacy+of+the+histone+deacetylase+inhibitor+suberoylanilide+hydroxamic+acid+in+combination+with+radiotherapy+in+a+malignant+rhabdoid+tumor+mouse+model.">In vivo efficacy of the histone deacetylase inhibitor suberoylanilide hydroxamic acid in combination with radiotherapy in a malignant rhabdoid tumor mouse model.</a> Radiation Oncology. 7 (1), 52 (2012).</li><li>Nicolay, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+retain+their+defining+stem+cell+characteristics+after+exposure+to+ionizing+radiation.">Mesenchymal stem cells retain their defining stem cell characteristics after exposure to ionizing radiation.</a> International Journal of Radiation Oncology Biology Physics. 87 (5), 1171-1178 (2013).</li><li>Nicolay, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+are+resistant+to+carbon+ion+radiotherapy.">Mesenchymal stem cells are resistant to carbon ion radiotherapy.</a> Oncotarget. 6 (4), 2076-2087 (2015).</li><li>Nicolay, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+exhibit+resistance+to+topoisomerase+inhibition.">Mesenchymal stem cells exhibit resistance to topoisomerase inhibition.</a> Cancer letters. 374 (1), 75-84 (2016).</li><li>Nicolay, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+maintain+their+defining+stem+cell+characteristics+after+treatment+with+cisplatin.">Mesenchymal stem cells maintain their defining stem cell characteristics after treatment with cisplatin.</a> Scientific Reports. 6, 20035 (2016).</li><li>Nicolay, N. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cells+are+sensitive+to+bleomycin+treatment.">Mesenchymal stem cells are sensitive to bleomycin treatment.</a> Scientific Reports. 6, 26645 (2016).</li><li>R&#252;hle, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cisplatin+radiosensitizes+radioresistant+human+mesenchymal+stem+cells.">Cisplatin radiosensitizes radioresistant human mesenchymal stem cells.</a> Oncotarget. 8 (50), 87809-87820 (2017).</li><li>M&#252;nz, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+mesenchymal+stem+cells+lose+their+functional+properties+after+paclitaxel+treatment.">Human mesenchymal stem cells lose their functional properties after paclitaxel treatment.</a> Scientific Reports. 8 (1), 312 (2018).</li><li>R&#252;hle, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Radiation+Resistance+of+Human+Multipotent+Mesenchymal+Stromal+Cells+Is+Independent+of+Their+Tissue+of+Origin.">The Radiation Resistance of Human Multipotent Mesenchymal Stromal Cells Is Independent of Their Tissue of Origin.</a> International Journal of Radiation Oncology Biology Physics. 100 (5), 1259-1269 (2018).</li><li>Dean, P. N., Jett, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mathematical+analysis+of+DNA+distributions+derived+from+flow+microfluorometry.">Mathematical analysis of DNA distributions derived from flow microfluorometry.</a> Journal of Cell Biology. 60 (2), 523-527 (1974).</li><li>Fox, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+for+the+computer+analysis+of+synchronous+DNA+distributions+obtained+by+flow+cytometry.">A model for the computer analysis of synchronous DNA distributions obtained by flow cytometry.</a> Cytometry. 1 (1), 71-77 (1980).</li><li>Costes, S. V., Boissi&#232;re, A., Ravani, S., Romano, R., Parvin, B., Barcellos-Hoff, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+features+that+discriminate+between+foci+induced+by+high-+and+low-LET+radiation+in+human+fibroblasts.">Imaging features that discriminate between foci induced by high- and low-LET radiation in human fibroblasts.</a> Radiation Research. 165 (5), 505-515 (2006).</li><li>Meyer, B., Voss, K. -. O., Tobias, F., Jakob, B., Durante, M., Taucher-Scholz, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clustered+DNA+damage+induces+pan-nuclear+H2AX+phosphorylation+mediated+by+ATM+and+DNA-PK.">Clustered DNA damage induces pan-nuclear H2AX phosphorylation mediated by ATM and DNA-PK.</a> Nucleic Acids Research. 41 (12), 6109-6118 (2013).</li><li>Lopez Perez, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superresolution+light+microscopy+shows+nanostructure+of+carbon+ion+radiation-induced+DNA+double-strand+break+repair+foci.">Superresolution light microscopy shows nanostructure of carbon ion radiation-induced DNA double-strand break repair foci.</a> FASEB. 30 (8), 2767-2776 (2016).</li><li>Schipler, A., Iliakis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+double-strand-break+complexity+levels+and+their+possible+contributions+to+the+probability+for+error-prone+processing+and+repair+pathway+choice.">DNA double-strand-break complexity levels and their possible contributions to the probability for error-prone processing and repair pathway choice.</a> Nucleic Acids Research. 41 (16), 7589-7605 (2013).</li><li>Stenerlow, B., Hoglund, E., Carlsson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+fragmentation+by+charged+particle+tracks.">DNA fragmentation by charged particle tracks.</a> Advances in Space Research. 30 (4), 859-863 (2002).</li><li>Friedland, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+track-structure+based+evaluation+of+DNA+damage+by+light+ions+from+radiotherapy-relevant+energies+down+to+stopping.">Comprehensive track-structure based evaluation of DNA damage by light ions from radiotherapy-relevant energies down to stopping.</a> Scientific Reports. 7, 45161 (2017).</li><li>Pang, D., Chasovskikh, S., Rodgers, J. E., Dritschilo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short+DNA+Fragments+Are+a+Hallmark+of+Heavy+Charged-Particle+Irradiation+and+May+Underlie+Their+Greater+Therapeutic+Efficacy.">Short DNA Fragments Are a Hallmark of Heavy Charged-Particle Irradiation and May Underlie Their Greater Therapeutic Efficacy.</a> Frontiers in Oncology. 6, 130 (2016).</li><li>B&#246;cker, W., Iliakis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computational+Methods+for+analysis+of+foci:+validation+for+radiation-induced+gamma-H2AX+foci+in+human+cells.">Computational Methods for analysis of foci: validation for radiation-induced gamma-H2AX foci in human cells.</a> Radiation Research. 165 (1), 113-124 (2006).</li><li>L&#246;brich, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#947;H2AX+foci+analysis+for+monitoring+DNA+double-strand+break+repair:+Strengths,+limitations+and+optimization.">&#947;H2AX foci analysis for monitoring DNA double-strand break repair: Strengths, limitations and optimization.</a> Cell Cycle. 9 (4), 662-669 (2010).</li></ol>

The featured method is easy to use and offers a fast, accurate and reproducible measurement of the DNA damage response including double-strand break (DSB) induction and repair, cell cycle effects and apoptotic cell death. The combination of these endpoints provides a more complete picture of their interrelations than individual assays. The method can be widely applied as a comprehensive genotoxicity assay in the fields of radiation biology, therapy and protection, and more generally in oncology (e.g., for environmental r...

The goal of oncology is to kill or to inactivate cancer cells without harming normal cells. Many therapies either directly or indirectly induce genotoxic stress in cancer cells, but also to some extend in normal cells. Chemotherapy or targeted drugs are often combined with radiotherapy to enhance the radiosensitivity of the irradiated tumor1,2,3,4,5, which allows for a reduction of the radiation dose to minimize normal tissue damage.
Ionizing radiation and other genotoxic agents induce different kinds of DNA damage, including base modifications, strand crosslinks and single- or double-strand breaks. DNA double-strand breaks (DSBs) are the most serious DNA lesions and their induction is key to the cell killing effect of ionizing radiation and various cytostatic drugs in radiochemotherapy. DSBs do not only harm the integrity of the genome, but also promote the formation of mutations6,7. Therefore, different DSB repair pathways, and mechanisms to eliminate irreparably damaged cells like apoptosis have developed during evolution. The entire DNA damage response (DDR) is regulated by a complex network of signaling pathways that reach from DNA damage recognition and cell cycle arrest to allow for DNA repair, to programmed cell death or inactivation in case of repair failure8.
The presented flow cytometric method has been developed to investigate the DDR after genotoxic stress in one comprehensive assay that covers DSB induction and repair, as well as consequences of repair failure. It combines the measurement of the widely applied DSB marker &#947;H2AX with analysis of the cell cycle and induction of apoptosis, using classical subG1 analysis and more specific evaluation of caspase-3 activation.
The combination of these endpoints in one assay not only reduces time, labor and cost expenses, but also enables cell cycle-specific measurement of DSB induction and repair, as well as caspase-3 activation. Such analyses would not be possible with independently conducted assays, but they are highly relevant for a comprehensive understanding of the DNA damage response after genotoxic stress. Many anti-cancer drugs, such as cytostatic compounds, are directed against dividing cells and their efficiency is strongly dependent on the cell cycle stage. The availability of different DSB repair processes is also dependent on the cell cycle stage and pathway choice which is critical for the repair accuracy, and in turn determines the fate of the cell9,10,11,12. In addition, cell cycle-specific measurement of DSB levels is more accurate than pooled analysis, because DSB levels are not only dependent on the dose of a genotoxic compound or radiation, but also on the DNA content of the cell.
The method has been used to compare the efficacy of different radiotherapies to overcome resistance mechanisms in glioblastoma13 and to dissect the interplay between ionizing radiation and targeted drugs in osteosarcoma14,15 and atypical teratoid rhabdoid cancers16. Additionally, the described method has been widely used to analyze side effects of radio- and chemotherapy on mesenchymal stem cells17,18,19,20,21,22,23,24, which are essential for the repair of treatment-induced normal tissue damage and have a potential application in regenerative medicine.

<table border="0" cellpadding="0" cellspacing="0" style="width:1064px;" width="1063">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:405px;">1000 &#181;L filter tips</td>
			<td style="width:151px;">Nerbe plus</td>
			<td style="width:169px;">07-693-8300</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="96">
			<td height="96" style="height:97px;">100-1000 &#181;L pipette</td>
			<td>Eppendorf</td>
			<td>3123000063</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">12 x 75 mm Tubes with Cell Strainer Cap, 35 &#181;m mesh pore size</td>
			<td>BD Falcon</td>
			<td>352235</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">15 mL tubes</td>
			<td>BD Falcon</td>
			<td>352096</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">200 &#181;L filter tips</td>
			<td>Nerbe plus</td>
			<td>07-662-8300</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">20-200 &#181;L pipette</td>
			<td>Eppendorf</td>
			<td>3123000055</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">4&#8217;,6-Diamidin-2-phenylindol (DAPI)</td>
			<td>Sigma-Aldrich</td>
			<td>D9542</td>
			<td style="width:339px;">Dissolve in water at 200 &#181;g/ml and store aliquots at -20 &#176;C</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:405px;">Alexa Fluor 488 anti-H2A.X Phospho (Ser139) Antibody, RRID: AB_2248011</td>
			<td>BioLegend</td>
			<td>613406</td>
			<td style="width:339px;">Dilute 1:20</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:405px;">Alexa Fluor 647 Rabbit Anti-Active Caspase-3 Antibody, AB_1727414</td>
			<td>BD Pharmingen</td>
			<td>560626</td>
			<td style="width:339px;">Dilute 1:20</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">BD FACSClean solution</td>
			<td>BD Biosciences</td>
			<td>340345</td>
			<td style="width:339px;">For cytometer cleaning routine after measurement</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">BD FACSRinse solution</td>
			<td>BD Biosciences</td>
			<td>340346</td>
			<td style="width:339px;">For cytometer cleaning routine after measurement</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Dulbecco&#8217;s Phosphate Buffered Saline (PBS)</td>
			<td>Biochrom</td>
			<td>L 182</td>
			<td style="width:339px;">Dissolve in water to 1x concentration</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Dulbecco&#39;s Modified Eagle&#39;s Medium with stable glutamin</td>
			<td>Biochrom</td>
			<td>FG 0415</td>
			<td style="width:339px;">Routine cell culture material for the example cell line used in the protocol</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Ethanol absolute</td>
			<td>VWR</td>
			<td>20821.330</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Excel software</td>
			<td>Microsoft</td>
			<td></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">FBS Superior (fetal bovine serum)</td>
			<td>Biochrom</td>
			<td>S 0615</td>
			<td style="width:339px;">Routine cell culture material for the example cell line used in the protocol</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">FlowJo v10 software</td>
			<td>LLC</td>
			<td>online order</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Fluoromount-G</td>
			<td>SouthernBiotech</td>
			<td>0100-01</td>
			<td style="width:339px;">Embedding medium for optional preparation of microscopic slides from stained samples</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">folded cellulose filters, grade 3hw</td>
			<td>NeoLab</td>
			<td>11416</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">LSRII or LSRFortessa cytometer</td>
			<td>BD Biosciences</td>
			<td></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">MG132</td>
			<td>Calbiochem</td>
			<td>474787</td>
			<td style="width:339px;">optional drug for apoptosis positive control</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Multifuge 3SR+</td>
			<td>Heraeus</td>
			<td></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Paraformaldehyde</td>
			<td>AppliChem</td>
			<td>A3813</td>
			<td style="width:339px;">Prepare 4.5% solution fresh. Dilute in PBS by heating to 80 &#176;C with slow stirring under the fume hood. Cover the flask with aluminium foil to prevent heat loss. Let the solution cool to room temperature and adjust the final volume. Pass the solution through a cellulose filter.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:405px;">Phospho-Histone H3 (Ser10) (D2C8) XP Rabbit mAb (Alexa Fluor&#174; 555 Conjugate) RRID: AB_10694639</td>
			<td>Cell Signaling Technology</td>
			<td>#3475</td>
			<td style="width:339px;">Dilute 3:200</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">PIPETBOY acu 2</td>
			<td>Integra Biosciences</td>
			<td>155 016</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Serological pipettes, 10 mL</td>
			<td>Corning</td>
			<td>4488</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Serological pipettes, 25 mL</td>
			<td>Corning</td>
			<td>4489</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Serological pipettes, 5 mL</td>
			<td>Corning</td>
			<td>4487</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">SuperKillerTRAIL (modified TNF-related apoptosis-inducing ligand)</td>
			<td>Biomol</td>
			<td>AG-40T-0002-C020</td>
			<td style="width:339px;">optional drug for apoptosis positive control</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">T25 cell culture flasks</td>
			<td>Greiner bio-one</td>
			<td>690160</td>
			<td style="width:339px;">Routine cell culture material for the example cell line used in the protocol</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Trypsin/EDTA</td>
			<td>PAN Biotech</td>
			<td>P10-025500</td>
			<td style="width:339px;">Routine cell culture material for the example cell line used in the protocol</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">U87 MG glioblastoma cells</td>
			<td>ATCC</td>
			<td>ATCC-HTB-14</td>
			<td style="width:339px;">Example cell line used in the protocol</td>
		</tr>
	</tbody>
</table>

cell cycle-specific measurement of &#947;h2ax and apoptosis after genotoxic stress by flow cytometry

The presented method or slightly modified versions have been devised to study specific treatment responses and side effects of various anti-cancer treatments as used in clinical oncology. It enables a quantitative and longitudinal analysis of the DNA damage response after genotoxic stress, as induced by radiotherapy and a multitude of anti-cancer drugs. The method covers all stages of the DNA damage response, providing endpoints for induction and repair of DNA double-strand breaks (DSBs), cell cycle arrest and cell death by apoptosis in case of repair failure. Combining these measurements provides information about cell cycle-dependent treatment effects and thus allows an in-depth study of the interplay between cellular proliferation and coping mechanisms against DNA damage. As the effect of many cancer therapeutics including chemotherapeutic agents and ionizing radiation is limited to or strongly varies according to specific cell cycle phases, correlative analyses rely on a robust and feasible method to assess the treatment effects on the DNA in a cell cycle-specific manner. This is not possible with single-endpoint assays and an important advantage of the presented method. The method is not restricted to any particular cell line and has been thoroughly tested in a multitude of tumor and normal tissue cell lines. It can be widely applied as a comprehensive genotoxicity assay in many fields of oncology besides radio-oncology, including environmental risk factor assessment, drug screening and evaluation of genetic instability in tumor cells.

Human U87 or LN229 glioblastoma cells were irradiated with 4 Gy of photon or carbon ion radiation. Cell cycle-specific &#947;H2AX levels and apoptosis were measured at different time points up to 48 h after irradiation using the flow cytometric method presented here (Figure 3). In both cell lines, carbon ions induced higher &#947;H2AX peak levels that declined slower and remained significantly elevated at 24 to 48 h compared to photon radiation at the same physical dose (<strong class="xfig"...

Watch this Scientific Journal Video about Cell Cycle-specific Measurement of Î³H2AX and Apoptosis After Genotoxic Stress by Flow Cytometry at JoVE.com

Cell Cycle-specific Measurement of &amp;#947;H2AX and Apoptosis After Genotoxic Stress by Flow Cytometry

The presented method combines the quantitative analysis of DNA double-strand breaks (DSBs), cell cycle distribution and apoptosis to enable cell cycle-specific evaluation of DSB induction and repair as well as the consequences of repair failure.

Cell Cycle-specific Measurement of &#947;H2AX and Apoptosis After Genotoxic Stress by Flow Cytometry

The presented method or slightly modified versions have been devised to study specific treatment responses and side effects of various anti-cancer ...

The method provides information about cell cycle dependent treatment effects and allows and in depth study of the interplay between cellular proliferation and coping mechanisms against DNA damage. This method combines important endpoints from the DNA damage response including double-strand frag recognition and repair, cell cycle effects, and eventual cell death by apoptosis into one comprehensive assay. We have used this technique mainly to investigate specific treatment responses and side effects of radiochemotherapeutic treatments in clinical oncology.The assay is very useful for correlative studies in the fields of radiobiology and radiotherapy, but it can also be applied to various other areas of oncology. After collecting the cells from the culture according to standard cell collection procedures, resuspend the pellet in one milliliter of PBS. And transfer the cells into two milliliters of fixation solution in a hood.After a 10 minute incubation at room temperature, collect the cells by centrifugation and decant the supernatant. It is important to fix the cells as a single cell suspension, and to keep the fixation time constant for all of the samples. Give adherent cells enough time to detach to obtain nicely rounded cells for analysis.Then loosen the pellet by tapping and resuspend the cells in three milliliters of 70%ethanol. To wash the cells before staining, sediment the cells by centrifugation, and loosen the pellet by tapping. Then resuspend the cells with two consecutive washes with three milliliters of washing solution and one wash with one milliliter of washing solution.Discarding the supernatant between each wash. After the last wash, carefully aspirate the supernatant without disturbing the pellet and resuspend the lucent pellet in 100 microliters of the antibody cocktail of interest. After one hour at room temperature, collect the cells by centrifugation and carefully aspirate the supernatant without disturbing the pellet.Then, resuspend the loosened pellet in 100 to 250 microliters of DNA staining solution and dispense the cells through the cell strainer cap of a sample tube with a 35 micrometer mesh pore size. To analyze the cells by flow cytometry, open the parameters tab in the cytometer window and select the parameters as indicated in the table. Next, open the worksheet window and create plots as indicated.Load a control sample onto the cytometer and press the run button. Select the first tube in the browser window and click the tube name. Adjust the detector voltages for forward and side scatter and DAPI in the parameters tab of the inspector window.Press the standby button to continue with the worksheet setup in the software. Use the polygon gate tool to define the cells'population in the forward scatter area versus the side scatter area plot and use the rectangle gate tool to define the single cells'population in the DAPI with versus DAPI area plot. Press control G to show the population hierarchy and click on the default gate names to rename them.Subsequently, right click on all of the histograms to select show populations and single cells from the context menu. Acquire control and treated samples to optimize the detector voltages for the antibody-coupled fluorophores to cover the full dynamic range of signal. To measure the samples, press the run button on the cytometer and use the acquisition dashboard in the software to measure the samples.Then select file, export, and experiments to select directory export in the dialog box to save the data as dot FCS files. To evaluate the data, drag and drop the dot FCS files into the sample browser of the flow cytometric analysis software. And use the polygon tool to define the cells'population in the forward versus side scatter area plot and to exclude debris from the analysis.In the DAPI with versus DAPI area plot, use the rectangle tool to define the single cells'population and to exclude any cell doublets or clumps from the analysis. In the DAPI area histogram, use the bisector tool to distinguish single cells with a normal DNA content from apoptotic cells with degraded DNA. Select tool biology and cell cycle to open the cell cycle modeling tool and select Dean-Jett Fox to estimate the frequency of cells in the G one S and G two M phases.Create G one S and G two and M phase gates in the DAPI with versus DAPI area plot of the cell cycle population to enable a cell cycle specific gamma H two A X measurement. Use the bisector tool to distinguish phosphohistone H three positive and negative cells in the Alexa 555 area histogram of the cell cycle population and to distinguish CAS base three positive and negative cells in the Alexa 647 area histogram of the single cells'population. Press control T to open the table editor and configure the table as indicated.Then select To File to set the format and destination in the output section of the menu ribbon and export the data into a spread sheet. Carbon ions induce higher gamma H two AX peak levels in glioblastoma cells that decline more slowly and remain significantly elevated in 24 to 48 hours compared to photon radiation at the same physical dose. For both carbon ions and photon radiation, the gamma H two AX levels were highest in G one phase cells likely because DNA double strand break repair is limited to the pathway of nonhomologous end joining at this stage in the cell cycle.In line with the higher double strand break induction rate and slower repair kinetics, carbon ions induce a stronger and longer lasting cell cycle arrest in G two phase and a higher rate of apoptosis than do photons. Depending on the strength of the treatment effect, the resolution of the different cell cycle phases can be challenging. In some cell lines, the DAPI concentration has a big impact on the quality of the cell cycle profile and needs to be adjusted.Slides can be prepared from the remaining samples after flow cytometry to evaluate the number, size, and shape of gamma H two AX foci and to distinguish between focal and parnuclear gamma H two AX staining. Using our method, we could show that mesenchymal stem cells are relatively resistant against ionizing radiations and topoisomerase inhibition but sensitive to gliomyacin. As PFA fumes are toxic, always use a fume hood when preparing the fixation solution and during the fixation step.Also remember to wear gloves when handling DAPI.

cell-cycle-specific-measurement-h2ax-apoptosis-after-genotoxic-stress

Research

JoVE Journal

Cancer Research

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the context of a whole organism. Sophisticated techniques to generate genetic mosaics facilitate induction of visually marked, genetically defined clones surrounded by normal tissue. The clones can be analyzed through diverse molecular, cellular and omics approaches. This study describes how to generate fluorescently labeled clonal tumors of varying malignancy in the eye/antennal imaginal discs (EAD) of Drosophila larvae using the Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. It describes procedures how to recover the mosaic EAD and brain from the larvae and how to process them for simultaneous imaging of fluorescent transgenic reporters and antibody staining. To facilitate molecular characterization of the mosaic tissue, we describe a protocol for isolation of total RNA from the EAD. The dissection procedure is suitable to recover EAD and brains from any larval stage. The fixation and staining protocol for imaginal discs works with a number of transgenic reporters and antibodies that recognize Drosophila proteins. The protocol for RNA isolation can be applied to various larval organs, whole larvae, and adult flies. Total RNA can be used for profiling of gene expression changes using candidate or genome-wide approaches. Finally, we detail a method for quantifying invasiveness of the clonal tumors. Although this method has limited use, its underlying concept is broadly applicable to other quantitative studies where cognitive bias must be avoided.

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

This protocol demonstrates how to generate fluorescently marked, genetically defined clonal tumors in the Drosophila eye/antennal imaginal discs (EAD). It describes how to dissect the EAD and brain from the third instar larvae and how to process them to visualize and quantify gene expression changes and tumor invasiveness.

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the ...

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro

Depletion of the mitochondrial membrane potential (MMP, &#916;&#936;m) is considered the earliest event in the apoptotic cascade. It even occurs ahead of nuclear apoptotic characteristics, including chromatin condensation and DNA breakage. Once the MMP collapses, cell apoptosis will initiate irreversibly. A series of lipophilic cationic dyes can pass through the cell membrane and aggregate inside the matrix of mitochondrion, and serve as fluorescence marker to evaluate MMP change. As one of the six members of the Cl- intracellular channel (CLIC) family, CLIC4 participates in the cell apoptotic process mainly through the mitochondrial pathway. Here we describe a detailed protocol to measure MMP via monitoring the fluorescence fluctuation of Rhodamine 123 (Rh123), through which we study apoptosis induced by CLIC4 knockdown. We discuss the advantages and limitations of the application of confocal laser scanning and normal fluorescence microscope in detail, and also compare it with other methods.

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro

Here we present a detailed protocol for the application of rhodamine 123 to identify the mitochondrial membrane potential (MMP) and study CLIC4 knockdown-induced HN4 cell apoptosis in vitro. Under common fluorescence microscope and confocal laser scanning fluorescence microscope, the real-time change of the MMP was recorded.

Depletion of the mitochondrial membrane potential (MMP, &#916;&#936;m) is considered the earliest event in the apoptotic cascade. It even occurs ahead of ...

Immunophenotyping of Orthotopic Homograft (Syngeneic) of Murine Primary KPC Pancreatic Ductal Adenocarcinoma by Flow Cytometry

Homograft (syngeneic) tumors are the workhorse of today&#39;s immuno-oncology (I/O) preclinical research. The tumor microenvironment (TME), particularly its immune-components, is vital to the prognosis and prediction of treatment outcomes, especially those of immunotherapy. TME immune-components are composed of different subsets of tumor-infiltrating immune cells assessable by multi-color FACS. Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest malignances lacking good treatment options, thus an urgent and unmet medical need. One important reason for its non-responsiveness to various therapies (chemo-, targeted, I/O) has been its abundant TME, consisting of fibroblasts and leukocytes that protect tumor cells from these therapies. Orthotopically implanted PDAC is believed to more accurately recapture the TME of human pancreatic cancers than conventional subcutaneous (SC) models.
Homograft tumors (KPC) are transplants of mouse spontaneous PDAC originating from genetically engineered KPC-mice (KrasG12D/+/P53-/-/Pdx1-Cre) (KPC-GEMM). The primary tumor tissue is cut into small fragments (~2 mm3) and transplanted subcutaneously (SC) to the syngeneic recipients (C57BL/6, 7&#8211;9 weeks old). The homografts were then surgically orthotopically transplanted onto the pancreas of new C57BL/6 mice, along with SC-implantation, which reached tumor volumes of 300&#8211;1,000 mm3 by 17 days. Only tumors of 400&#8211;600 mm3 were harvested per approved autopsy procedure and cleaned to remove the adjacent non-tumor tissues. They were dissociated per protocol using a tissue dissociator into single-cell suspensions, followed by staining with designated panels of fluorescently-labeled antibodies for various markers of different immune cells (lymphoid, myeloid and NK, DCs). The stained samples were analyzed using multi-color FACS to determine numbers of immune cells of different lineages, as well as their relative percentage within tumors. The immune profiles of orthotopic tumors were then compared to those of SC tumors. The preliminary data demonstrated significantly elevated infiltrating TILs/TAMs in tumors over the pancreas, and higher B-cell infiltration into orthotopic rather than SC tumors.

Immunophenotyping of Orthotopic Homograft Syngeneic of Murine Primary KPC Pancreatic Ductal Adenocarcinoma by Flow Cytometry

The experimental procedure on the immunophenotyping of murine orthotopic PDAC homografts aims at profiling the tumor immuno-microenvironment. Tumors are orthotopically implanted via surgery. Tumors of 200&#8211;600 mm3 in size were harvested and dissociated to prepare single-cell suspensions, followed by multi-immune marker FACS analysis using different fluorescently-labeled antibodies.

Homograft (syngeneic) tumors are the workhorse of today&#39;s immuno-oncology (I/O) preclinical research. The tumor microenvironment (TME), particularly ...

Phospho Flow Cytometry with Fluorescent Cell Barcoding for Single Cell Signaling Analysis and Biomarker Discovery

Aberrant cell signaling plays a central role in cancer development and progression. Most novel targeted therapies are indeed directed at proteins and protein functions, and cell signaling aberrations may therefore serve as biomarkers to indicate personalized treatment options. As opposed to DNA and RNA analyses, changes in protein activity can more efficiently evaluate the mechanisms underlying drug sensitivity and resistance. Phospho flow cytometry is a powerful technique that measures protein phosphorylation events at the cellular level, an important feature that distinguishes this method from other antibody-based approaches. The method allows for simultaneous analysis of multiple signaling proteins. In combination with fluorescent cell barcoding, larger medium- to high-throughput data-sets can be acquired by standard cytometer hardware in short time. Phospho flow cytometry has applications both in studies of basic biology and in clinical research, including signaling analysis, biomarker discovery and assessment of pharmacodynamics. Here, a detailed experimental protocol is provided for phospho flow analysis of purified peripheral blood mononuclear cells, using chronic lymphocytic leukemia cells as an example.

Here, a protocol for medium- to high-throughput analysis of protein phosphorylation events at the cellular level is presented. Phospho flow cytometry is a powerful approach to characterize signaling aberrations, identify and validate biomarkers, and assess pharmacodynamics.

Aberrant cell signaling plays a central role in cancer development and progression. Most novel targeted therapies are indeed directed at proteins and ...

Flow Cytometric Detection of Newly-formed Breast Cancer Stem Cell-like Cells After Apoptosis Reversal

Cancer recurrence has long been studied by oncologists while the underlying mechanisms remain unclear. Recently, we and others found that a phenomenon named apoptosis reversal leads to increased tumorigenicity in various cell models under different stimuli. Previous studies have been focused on tracking this process in vitro and in vivo; however, the isolation of real reversed cells has yet to be achieved, which limits our understanding on the consequences of apoptosis reversal. Here, we take advantage of a Caspase-3/7 Green Detection dye to label cells with activated caspases after apoptotic induction. Cells with positive signals are further sorted out by fluorescence-activated cell sorting (FACS) for recovery. Morphological examination under confocal microscopy helps confirm the apoptotic status before FACS. An increase in tumorigenicity can often be attributed to the elevation in the percentage of cancer stem cell (CSC)-like cells. Also, given the heterogeneity of breast cancer, identifying the origin of these CSC-like cells would be critical to cancer treatment. Thus, we prepare breast non-stem cancer cells before triggering apoptosis, isolating caspase-activated cells and performing the apoptosis reversal procedure. Flow cytometry analysis reveals that breast CSC-like cells re-appear in the reversed group, indicating breast CSC-like cells are transited from breast non-stem cancer cells during apoptosis reversal. In summary, this protocol includes the isolation of apoptotic breast cancer cells and detection of changes in CSC percentage in reversed cells by flow cytometry.

Here, we present a protocol to isolate apoptotic breast cancer cells by fluorescence-activated cell sorting and further detect the transition of breast non-stem cancer cells to breast cancer stem cell-like cells after apoptosis reversal by flow cytometry.

Cancer recurrence has long been studied by oncologists while the underlying mechanisms remain unclear. Recently, we and others found that a phenomenon ...

Real Time Detection of In Vitro Tumor Cell Apoptosis Induced by CD8+ T Cells to Study Immune Suppressive Functions of Tumor-infiltrating Myeloid Cells

Potentiation of the tumor-killing ability of CD8+ T cells in tumors, along with their efficient tumor infiltration, is a key element of successful immunotherapies. Several studies have indicated that tumor infiltrating myeloid cells (e.g., myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs)) suppress cytotoxicity of CD8+ T cells in the tumor microenvironment, and that targeting these regulatory myeloid cells can improve immunotherapies. Here, we present an in vitro assay system to evaluate immune suppressive effects of monocytic-MDSCs and TAMs on the tumor-killing ability of CD8+ T cells. To this end, we first cultured na&#239;ve splenic CD8+ T cells with anti-CD3/CD28 activating antibodies in the presence or absence of suppressor cells, and then co-cultured the pre-activated T cells with target cancer cells in the presence of a fluorogenic caspase-3 substrate. Fluorescence from the substrate in cancer cells was detected by real-time fluorescence microscopy as an indicator of T-cell induced tumor cell apoptosis. In this assay, we can successfully detect the increase of tumor cell apoptosis by CD8+ T cells and its suppression by pre-culture with TAMs or MDSCs. This functional assay is useful for investigating CD8+ T cell suppression mechanisms by regulatory myeloid cells and identifying druggable targets to overcome it via high throughput screening.

Real Time Detection of In Vitro Tumor Cell Apoptosis Induced by CD8+ T Cells to Study Immune Suppressive Functions of Tumor-infiltrating Myeloid Cells

We describe here a protocol to investigate cytotoxicity of pre-activated CD8+ T cells against cancer cells by detecting apoptotic cancer cells via real-time microscopy. This protocol can investigate mechanisms behind myeloid cell-induced T cell suppression and evaluate compounds aimed at replenishing T cells via blockade of immune suppressive myeloid cells.

Potentiation of the tumor-killing ability of CD8+ T cells in tumors, along with their efficient tumor infiltration, is a key element of successful ...

In Vivo Immunofluorescence Localization for Assessment of Therapeutic and Diagnostic Antibody Biodistribution in Cancer Research

Monoclonal antibodies (mAbs) are important tools in cancer detection, diagnosis, and treatment. They are used to unravel the role of proteins in tumorigenesis, can be directed to cancer biomarkers enabling tumor detection and characterization, and can be used for cancer therapy as mAbs or antibody-drug conjugates to activate immune effector cells, to inhibit signaling pathways, or directly kill cells carrying the specific antigen. Despite clinical advancements in the development and production of novel and highly specific mAbs, diagnostic and therapeutic applications can be impaired by the complexity and heterogeneity of the tumor microenvironment. Thus, for the development of efficient antibody-based therapies and diagnostics, it is crucial to assess the biodistribution and interaction of the antibody-based conjugate with the living tumor microenvironment. Here, we describe In Vivo Immunofluorescence Localization (IVIL) as a new approach to study interactions of antibody-based therapeutics and diagnostics in the in vivo physiological and pathological conditions. In this technique, a therapeutic or diagnostic antigen-specific antibody is intravenously injected in&#160;vivo and localized ex vivo with a secondary antibody in isolated tumors. IVIL, therefore, reflects the in vivo biodistribution of antibody-based drugs and targeting agents. Two IVIL applications are described assessing the biodistribution and accessibility of antibody-based contrast agents for molecular imaging of breast cancer. This protocol will allow future users to adapt the IVIL method for their own antibody-based research applications.

The in vivo immunofluorescence localization (IVIL) method can be used to examine in vivo biodistribution of antibodies and antibody conjugates for oncological purposes in living organisms using a combination of in vivo tumor targeting and ex vivo immunostaining methods.

Monoclonal antibodies (mAbs) are important tools in cancer detection, diagnosis, and treatment. They are used to unravel the role of proteins in ...

In Vivo Immunogenicity Screening of Tumor-Derived Extracellular Vesicles by Flow Cytometry of Splenic T Cells

Immunogenic cell death of tumors, caused by chemotherapy or irradiation, can trigger tumor-specific T cell responses by releasing danger-associated molecular patterns and inducing the production of type I interferon. Immunotherapies, including checkpoint inhibition, primarily rely on preexisting tumor-specific T cells to unfold a therapeutic effect. Thus, synergistic therapeutic approaches that exploit immunogenic cell death as an intrinsic anti-cancer vaccine may improve their responsiveness. However, the spectrum of immunogenic factors released by cells under therapy-induced stress remains incompletely characterized, especially regarding extracellular vesicles (EVs). EVs, nano-scale membranous particles emitted from virtually all cells, are considered to facilitate intercellular communication and, in cancer, have been shown to mediate cross-priming against tumor antigens. To assess the immunogenic effect of EVs derived from tumors under various conditions, adaptable, scalable, and valid methods are sought-for. Therefore, herein a relatively easy and robust approach is presented to assess EVs' in vivo immunogenicity. The protocol is based on flow cytometry analysis of splenic T cells after in vivo immunization of mice with EVs, isolated by precipitation-based assays from tumor cell cultures under therapy or steady-state conditions. For example, this work shows that oxaliplatin exposure of B16-OVA murine melanoma cells resulted in the release of immunogenic EVs that can mediate the activation of tumor-reactive cytotoxic T cells. Hence, screening of EVs via in vivo immunization and flow cytometry identifies conditions under which immunogenic EVs can emerge. Identifying conditions of immunogenic EV release provides an essential prerequisite to testing EVs' therapeutic efficacy against cancer and exploring the underlying molecular mechanisms to ultimately unveil new insights into EVs' role in cancer immunology.

In Vivo Immunogenicity Screening of Tumor-Derived Extracellular Vesicles by Flow Cytometry of Splenic T Cells

This manuscript describes how to assess in vivo immunogenicity of tumor cell-derived extracellular vesicles (EVs) using flow cytometry. EVs derived from tumors undergoing treatment-induced immunogenic cell death seem particularly relevant in tumor immunosurveillance. This protocol exemplifies the assessment of oxaliplatin-induced immunostimulatory tumor EVs but can be adapted to various settings.

Immunogenic cell death of tumors, caused by chemotherapy or irradiation, can trigger tumor-specific T cell responses by releasing danger-associated ...

Simultaneous Imaging and Flow-Cytometry-based Detection of Multiple Fluorescent Senescence Markers in Therapy-Induced Senescent Cancer Cells

Chemotherapeutic drugs can induce irreparable DNA damage in cancer cells, leading to apoptosis or premature senescence. Unlike apoptotic cell death, senescence is a fundamentally different machinery restraining&#160;propagation of cancer cells. Decades of scientific studies have revealed the complex pathological effects of senescent cancer cells in tumors and microenvironments that modulate cancer cells and stromal cells. New evidence suggests that senescence is a potent prognostic factor during cancer treatment, and therefore rapid and accurate detection of senescent cells in cancer samples is essential. This paper presents a method to visualize and detect therapy-induced senescence (TIS) in cancer cells. Diffuse large B-cell lymphoma (DLBCL) cell lines were treated with mafosfamide (MAF) or daunorubicin (DN) and examined for the senescence marker, senescence-associated &#946;-galactosidase (SA-&#946;-gal), the DNA synthesis marker 5-ethynyl-2&#8242;-deoxyuridine (EdU), and the DNA damage marker gamma-H2AX (&#947;H2AX). Flow cytometer imaging can help generate high-resolution single-cell images in a short period of time to simultaneously visualize and quantify the three markers in cancer cells.

Here we present a flow cytometry-based method for visualization and quantification of multiple senescence-associated markers in single cells.

Chemotherapeutic drugs can induce irreparable DNA damage in cancer cells, leading to apoptosis or premature senescence. Unlike apoptotic cell death, ...

Far-Red Fluorescent Senescence-Associated &#946;-Galactosidase Probe for Identification and Enrichment of Senescent Tumor Cells by Flow Cytometry

Cellular senescence is a state of proliferative arrest induced by biological damage that normally accrues over years in aging cells but may also emerge rapidly in tumor cells as a response to damage induced by various cancer treatments. Tumor cell senescence is generally considered undesirable, as senescent cells become resistant to death and block tumor remission while exacerbating tumor malignancy and treatment resistance. Therefore, the identification of senescent tumor cells is of ongoing interest to the cancer research community. Various senescence assays exist, many based on the activity of the well-known senescence marker, senescence-associated beta-galactosidase (SA-&#946;-Gal). 
Typically, the SA-&#946;-Gal assay is performed using a chromogenic substrate (X-Gal) on fixed cells, with the slow and subjective enumeration of "blue" senescent cells by light microscopy. Improved assays using cell-permeant, fluorescent SA-&#946;-Gal substrates, including C12-FDG (green) and DDAO-Galactoside (DDAOG; far-red), have enabled the analysis of living cells and allowed the use of high-throughput fluorescent analysis platforms, including flow cytometers. C12-FDG is a well-documented probe for SA-&#946;-Gal, but its green fluorescent emission overlaps with intrinsic cellular autofluorescence (AF) that arises during senescence due to the accumulation of lipofuscin aggregates. By utilizing the far-red SA-&#946;-Gal probe DDAOG, green cellular autofluorescence can be used as a secondary parameter to confirm senescence, adding reliability to the assay. The remaining fluorescence channels can be used for cell viability staining or optional fluorescent immunolabeling.
Using flow cytometry, we demonstrate the use of DDAOG and lipofuscin autofluorescence as a dual-parameter assay for the identification of senescent tumor cells. Quantitation of the percentage of viable senescent cells is performed. If desired, an optional immunolabeling step may be included to evaluate cell surface antigens of interest. Identified senescent cells can also be flow cytometrically sorted and collected for downstream analysis. Collected senescent cells can be immediately lysed (e.g., for immunoassays or 'omics analysis) or further cultured.

Far-Red Fluorescent Senescence-Associated &amp;#946;-Galactosidase Probe for Identification and Enrichment of Senescent Tumor Cells by Flow Cytometry

A protocol for fluorescent, flow cytometric quantification of senescent cancer cells induced by chemotherapy drugs in cell culture or in murine tumor models is presented. Optional procedures include co-immunostaining, sample fixation to facilitate large batch or time point analysis, and the enrichment of viable senescent cells by flow cytometric sorting.

Cellular senescence is a state of proliferative arrest induced by biological damage that normally accrues over years in aging cells but may also emerge ...