Name: flow cytometry-based drug screening system for the identification of small molecules that promote cellular differentiation of glioblastoma stem cells
Uploaded: 2018-01-10T14:00:00
Description: Watch this Scientific Journal Video about Flow Cytometry-based Drug Screening System for the Identification of Small Molecules That Promote Cellular Differentiation of Glioblastoma Stem Cells at JoVE.

This work has been partially supported by NIH R01CA187780.

NOTE: Astroglial and neuronal lentivirus reporter systems were purchased as pre-packaged, concentrated lentiviral preparations. Basic knowledge of flow cytometry technique is required. Also, for a full use of this protocol the user will need access to a flow cytometer with high throughput capacity (accepts 96-well plates as sample source).
1. Lentiviral Transcriptional Reporter System
NOTE: In all flow cytometric analyses, use parental, non-transduced, cells or vector...

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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Malignant+gliomas:+new+translational+therapies.">Malignant gliomas: new translational therapies.</a> Mt Sinai J Med. 77 (6), 655-666 (2010).</li><li>Bar, E. E., Chaudhry, A., Farah, M. H., Eberhart, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hedgehog+signaling+promotes+medulloblastoma+survival+via+Bc/II.">Hedgehog signaling promotes medulloblastoma survival via Bc/II.</a> Am J Pathol. 170 (1), 347-355 (2007).</li><li>Chu, Q., Orr, B. A., Semenkow, S., Bar, E. E., Eberhart, C. 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E., 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=Cyclopamine-mediated+hedgehog+pathway+inhibition+depletes+stem-like+cancer+cells+in+glioblastoma.">Cyclopamine-mediated hedgehog pathway inhibition depletes stem-like cancer cells in glioblastoma.</a> Stem Cells. 25 (10), 2524-2533 (2007).</li><li>Bar, E. E., Lin, A., Mahairaki, V., Matsui, W., Eberhart, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia+increases+the+expression+of+stem-cell+markers+and+promotes+clonogenicity+in+glioblastoma+neurospheres.">Hypoxia increases the expression of stem-cell markers and promotes clonogenicity in glioblastoma neurospheres.</a> Am J Pathol. 177 (3), 1491-1502 (2010).</li><li>Kahlert, U. D., 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=CD133/CD15+defines+distinct+cell+subpopulations+with+differential+in+vitro+clonogenic+activity+and+stem+cell-related+gene+expression+profile+in+in+vitro+propagated+glioblastoma+multiforme-derived+cell+line+with+a+PNET-like+component.">CD133/CD15 defines distinct cell subpopulations with differential in vitro clonogenic activity and stem cell-related gene expression profile in in vitro propagated glioblastoma multiforme-derived cell line with a PNET-like component.</a> Folia Neuropathol. 50 (4), 357-368 (2012).</li><li>Lim, K. 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=Inhibition+of+monocarboxylate+transporter-4+depletes+stem-like+glioblastoma+cells+and+inhibits+HIF+transcriptional+response+in+a+lactate-independent+manner.">Inhibition of monocarboxylate transporter-4 depletes stem-like glioblastoma cells and inhibits HIF transcriptional response in a lactate-independent manner.</a> Oncogene. 33 (35), 4433-4441 (2014).</li><li>Kahlert, U. D., 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=ZEB1+Promotes+Invasion+in+Human+Fetal+Neural+Stem+Cells+and+Hypoxic+Glioma+Neurospheres.">ZEB1 Promotes Invasion in Human Fetal Neural Stem Cells and Hypoxic Glioma Neurospheres.</a> Brain Pathol. 25 (6), 724-732 (2014).</li><li>Hu, Y., Smyth, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ELDA:+extreme+limiting+dilution+analysis+for+comparing+depleted+and+enriched+populations+in+stem+cell+and+other+assays.">ELDA: extreme limiting dilution analysis for comparing depleted and enriched populations in stem cell and other assays.</a> J Immunol Methods. 347 (1-2), 70-78 (2009).</li><li>Meyer, 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=Single+cell-derived+clonal+analysis+of+human+glioblastoma+links+functional+and+genomic+heterogeneity.">Single cell-derived clonal analysis of human glioblastoma links functional and genomic heterogeneity.</a> Proc Natl Acad Sci U S A. 112 (3), 851-856 (2015).</li><li>Galli, 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=Isolation+and+characterization+of+tumorigenic,+stem-like+neural+precursors+from+human+glioblastoma.">Isolation and characterization of tumorigenic, stem-like neural precursors from human glioblastoma.</a> Cancer Res. 64 (19), 7011-7021 (2004).</li><li>Spina, R., Voss, D. 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While most of the previous studies of GSCs focused primarily on the markers that define them, in this study we decided to take the reverse approach. We focus primarily on the differentiated progenies generated by GSCs (e.g., cells expressing astroglial and neuronal markers). Here we demonstrate the utilization of a cell-based high throughput drug screening system, which is based on human GFAP promoter-dependent expression of GFP. All the experiments were performed utilizing patient-derived neurosphere glioblastoma cell l...

Recent studies have shown that tumors contain a small population of cells, termed cancer stem cells (CSCs) or tumor-initiating cells, which are responsible for tumor progression, metastasis, and resistance to chemo- and radio-therapies 1,2. The presence of cancer stem cells and their more differentiated progenies within tumors is considered an important factor promoting intratumoral heterogeneity and thus represents a major hurdle in treating cancers3. Tumor cell hierarchy, provided by the cancer stem cell theory, has inspired the development of new strategies to treat cancers 4. One approach for targeting cancer stem cells is to identify and inhibit signaling pathways that are known to be required during embryonic development of the affected organ. Indeed, we and others have previously published multiple papers describing the ongoing requirement for the neural stem cell-relevant signaling pathways Sonic Hedgehog and Notch in glioblastoma5,6,7. This work has helped in solidifying the rationale for several GBM clinical trials. A second approach for targeting cancer stem cells is to promote their differentiation. This approach has received a lot of support due to the favorable results from preclinical and clinical studies in treating acute promyelocytic leukemia with retinoic acids (ATRA, a vitamin-A analog). Here ATRA was found to remove the maturation block and promote cancer cell differentiation8. More recently, Piccirillo and colleagues have elegantly shown that BMP-4 promotes GSC differentiation into astrocytes with significant anti-GBM effects in vitro and in vivo9.
The rationale for the current study is based on a &#34;reversed engineering&#34; approach for targeting GSCs. Given the vast heterogeneity present in GBM and with poor differentiation being one of the hallmarks of cancer, we asked if we could promote a more favorable phenotype - differentiation into an astrocyte-like state. Here, we do not have prior knowledge of the signaling pathways that maintain GSCs in a given tumor specimen but rather aim to achieve a desired phenotype (e.g. GFAP positivity).
This report describes the procedures used to establish GSC differentiation reporter-lines from the transduction of GSC-enriched cultures to GSC clonal selection. The glioblastoma neurosphere lines used were established at the laboratory of Professor Angelo Vescovi from patients with a diagnosis of primary glioblastoma at Hospital San Raffaele - Milano, Italy. These lines have been extensively studied in several publications 6,10,11,12,13,14. It is highly recommended that individuals who are interested in implementing these techniques in their laboratory determine the relevance of the reporter to cancer stem cell self-renewal capacity in the cells they plan to study (this is true for any reporter). A detailed protocol for one of the in vitro clonogenic assays accepted in the field is provided to accomplish this15,16. Finally, a detailed protocol describing the utilization of the differentiation reporter-lines in a flow-cytometry based drug screen is provided at the end. Of note, similarly to the astroglial differentiation system described here, we have successfully established and validated GSC reporter lines integrating an MAP2:GFP (neuronal differentiation) reporter. Therefore, the methodologies describe in this paper may be applied to study cellular differentiation into various cell lineages.
Some of the figures in this report can be found in a recent publication: &#34;Atracurium Besylate and other neuromuscular blocking agents promote astroglial differentiation and deplete glioblastoma stem cells18.

<table>
	<tbody>
		<tr>
			<td>ESGRO Complete Accutase</td>
			<td>EMD Millipore</td>
			<td>SF006</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>Sigma Aldrich</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS (Hank&#39;s Balanced Salt Solution)</td>
			<td>Sigma Aldrich</td>
			<td>H6648</td>
			<td></td>
		</tr>
		<tr>
			<td>Human GFAP Differentiation Reporter (pGreenZeo, Virus)</td>
			<td>SBI (System Biosciences)</td>
			<td>SR10015VA-1</td>
			<td></td>
		</tr>
		<tr>
			<td>50 ml sterile disposable reagent reservoirs</td>
			<td>Corning</td>
			<td>4870</td>
			<td></td>
		</tr>
		<tr>
			<td>6 well plate</td>
			<td>Thermo Fisher Scientific</td>
			<td>130184</td>
			<td></td>
		</tr>
		<tr>
			<td>96 well plate</td>
			<td>Falcon</td>
			<td>353072</td>
			<td></td>
		</tr>
		<tr>
			<td>Biolite T25 cm&#178; Flask Vented</td>
			<td>Thermo Fisher Scientific</td>
			<td>130189</td>
			<td></td>
		</tr>
		<tr>
			<td>Biolite T75 cm&#178; Flask Vented</td>
			<td>Thermo Fisher Scientific</td>
			<td>130190</td>
			<td></td>
		</tr>
		<tr>
			<td>15 ml Centrifuge tubes</td>
			<td>Celltreat</td>
			<td>229411</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5ml Microcentrifuge tubes</td>
			<td>Fisher Scientific</td>
			<td>05-408-129</td>
			<td></td>
		</tr>
		<tr>
			<td>Ovation Multi Channel Pipette, 12 Channel, 0.5 - 20uL</td>
			<td>VistaLab Technologies</td>
			<td>1060-0020</td>
			<td></td>
		</tr>
		<tr>
			<td>Ovation Multi Channel Pipette, 12 Channel, 5-250uL</td>
			<td>VistaLab Technologies</td>
			<td>1060-0250</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi 12-channel pipette tips 25 &#956;l</td>
			<td>VistaLab Technologies</td>
			<td>4060-1002</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi 12-channel pipette tips 250 &#956;l</td>
			<td>VistaLab Technologies</td>
			<td>4060-9025</td>
			<td></td>
		</tr>
		<tr>
			<td>Guava easyCyte 5HT Benchtop Flow Cytometer</td>
			<td>EMD Millipore</td>
			<td>0500-4005</td>
			<td></td>
		</tr>
		<tr>
			<td>NIH Clinical Collections 1 and 2 small molecule libraries</td>
			<td>Evotec</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>For the preparation of neural stem cell media (500 mL)</td>
			<td></td>
			<td></td>
			<td>Final concentration</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>GoldBio.com</td>
			<td>A-421-250</td>
			<td>0.20%</td>
		</tr>
		<tr>
			<td>DMEM/F12 10X</td>
			<td>Corning</td>
			<td>90-091-PB</td>
			<td>1X</td>
		</tr>
		<tr>
			<td>Heparin sodium salt</td>
			<td>Sigma Aldrich</td>
			<td>H3149</td>
			<td>0.0002%</td>
		</tr>
		<tr>
			<td>HEPES 1M</td>
			<td>Sigma Aldrich</td>
			<td>H4036</td>
			<td>5.4 mM</td>
		</tr>
		<tr>
			<td>Insulin-Transferrin- Selenium (ITS -G) (100X)</td>
			<td>Life Technologies</td>
			<td>41400-045</td>
			<td>1X</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Sigma Aldrich</td>
			<td>S-5761</td>
			<td>14.5 mM</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin (10,000 U/mL) 100X</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td>1X</td>
		</tr>
		<tr>
			<td>Progesterone</td>
			<td>Sigma Aldrich</td>
			<td>P8783</td>
			<td>16 nM</td>
		</tr>
		<tr>
			<td>Putrescine</td>
			<td>Sigma Aldrich</td>
			<td>P5780</td>
			<td>4.8 &#181;M</td>
		</tr>
		<tr>
			<td>Basic FGF (FGF2), Human</td>
			<td>GoldBio</td>
			<td>1140-02-50</td>
			<td>10 ng/ml</td>
		</tr>
		<tr>
			<td>EGF, Human</td>
			<td>GoldBio</td>
			<td>1150-04-100</td>
			<td>20 ng/ml</td>
		</tr>
		<tr>
			<td>Bottle-Top Filter, 150ml, 33mm, 0.22um, Pes, S, Ind</td>
			<td>Corning</td>
			<td>431160</td>
			<td>Use to filter sterlize media</td>
		</tr>
	</tbody>
</table>

flow cytometry-based drug screening system for the identification of small molecules that promote cellular differentiation of glioblastoma stem cells

Glioblastoma (GBM) is the most common and most lethal primary brain tumor in adults, causing roughly 14,000 deaths each year in the U.S. alone. Median survival following diagnosis is less than 15 months with maximal surgical resection, radiation, and temozolomide chemotherapy. The challenges inherent in developing more effective GBM treatments have become increasingly clear, and include its unyielding invasiveness, its resistance to standard treatments, its genetic complexity and molecular adaptability, and subpopulations of GBM cells with phenotypic similarities to normal stem cells, herein referred to as glioblastoma stem cells (GSCs). Because GSCs are required for tumor growth and progression, differentiation-based therapy represents a viable treatment modality for these incurable neoplasms. 
The following protocol describes a collection of procedures to establish a high throughput screening platform aimed at the identification of small molecules that promote GSC astroglial differentiation. At the core of the system is a glial fibrillary acidic protein (GFAP) differentiation reporter-construct. The protocol contains the following general procedures: (1) establishing GSC differentiation reporter lines; (2) testing/validating the relevance of the reporter to GSC self-renewal/clonogenic capacity; and (3) high-capacity flow-cytometry based drug screening. 
The screening platform provides a straightforward and inexpensive approach to identify small molecules that promote GSCs differentiation. Furthermore, utilization of libraries of FDA-approved drugs holds the potential for the identification of agents that can be repurposed more rapidly. Also, therapies that promote cancer stem cell differentiation are expected to work synergistically with current "standard of care" therapies that have been shown to target and eliminate primarily more differentiated cancer cells.

Three independent patient-derived neurospheres lines were transduced with the lentivirus astroglial reporter encoding for a green-fluorescent protein (GFP) fused in-frame with a Zeocin resistance cassette and driven by the human GFAP promoter element (Figure 1). Next individual clones were isolated by plating 0.7 cells per well in a 96 well plate (Figure 2), this was followed by flow cytometric determination of the percentage of ...

Watch this Scientific Journal Video about Flow Cytometry-based Drug Screening System for the Identification of Small Molecules That Promote Cellular Differentiation of Glioblastoma Stem Cells at JoVE.

Flow Cytometry-based Drug Screening System for the Identification of Small Molecules That Promote Cellular Differentiation of Glioblastoma Stem Cells

An efficient screening protocol is presented for the identification of small molecules that promote astroglial differentiation in glioblastoma stem cells (GSCs). The assay is based on a stem cell differentiation reporter whereby the expression of the enhanced GFP (eGFP) is driven by the human GFAP promoter.

Glioblastoma (GBM) is the most common and most lethal primary brain tumor in adults, causing roughly 14,000 deaths each year in the U.S. alone. Median ...

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