All procedures performed with mice were approved by the Animal Research Committee of Tokyo Women&#39;s Medical University.
1.Tail Vein Injection of Lewis Lung Carcinoma (LLC) Cells
<ol>
	<li>Maintain LLC cells in DMEM supplemented with 10% FCS, in a humidified 5% CO2 incubator at 37 &#176;C. Cells should contain a fluorescent protein expression system (e.g., GFP).</li>
	<li>Remove cells from culture dish by using a non-enzymatic cell dissociation reagent. Follow manufactu...

<ol>
	<li>Valastyan, S., Weinberg, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+metastasis:+molecular+insights+and+evolving+paradigms.">Tumor metastasis: molecular insights and evolving paradigms.</a> Cell. 147 (2), 275-292 (2011).</li><li>Kaplan, R. N., 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=VEGFR1-positive+haematopoietic+bone+marrow+progenitors+initiate+the+pre-metastatic+niche.">VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche.</a> Nature. 438 (7069), 820-827 (2005).</li><li>Hiratsuka, S., Watanabe, A., Aburatani, H., Maru, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumour-mediated+upregulation+of+chemoattractants+and+recruitment+of+myeloid+cells+predetermines+lung+metastasis.">Tumour-mediated upregulation of chemoattractants and recruitment of myeloid cells predetermines lung metastasis.</a> Nature Cell Biology. 8 (12), 1369-1375 (2006).</li><li>Hiratsuka, 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=The+S100A8-serum+amyloid+A3-TLR4+paracrine+cascade+establishes+a+pre-metastatic+phase.">The S100A8-serum amyloid A3-TLR4 paracrine cascade establishes a pre-metastatic phase.</a> Nature Cell Biology. 10 (11), 1349-1355 (2008).</li><li>Tomita, T., Sakurai, Y., Ishibashi, S., Maru, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imbalance+of+Clara+cell-mediated+homeostatic+inflammation+is+involved+in+lung+metastasis.">Imbalance of Clara cell-mediated homeostatic inflammation is involved in lung metastasis.</a> Oncogene. 30 (31), 3429-3439 (2011).</li><li>Deguchi, 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=Serum+amyloid+A3+binds+MD-2+to+activate+p38+and+NF-&#954;B+pathways+in+a+MyD88-dependent+manner.">Serum amyloid A3 binds MD-2 to activate p38 and NF-&#954;B pathways in a MyD88-dependent manner.</a> Journal of Immunology. 191 (4), 1856-1864 (2013).</li><li>Erler, J. T., 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=Hypoxia-induced+lysyl+oxidase+is+a+critical+mediator+of+bone+marrow+cell+recruitment+to+form+the+premetastatic+niche.">Hypoxia-induced lysyl oxidase is a critical mediator of bone marrow cell recruitment to form the premetastatic niche.</a> Cancer Cell. 15, 35-44 (2009).</li><li>Huang, Y., 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=Pulmonary+vascular+destabilization+in+the+premetastatic+phase+facilitates+lung+metastasis.">Pulmonary vascular destabilization in the premetastatic phase facilitates lung metastasis.</a> Cancer Research. 69 (19), 7292-7237 (2009).</li><li>Sceneay, J., Smyth, M. J., M&#246;ller, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pre-metastatic+niche:+finding+common+ground.">The pre-metastatic niche: finding common ground.</a> Cancer Metastasis Reviews. 32 (3-4), 449-464 (2013).</li><li>Castle, J., Shaker, H., Morris, K., Tugwood, J. D., Kirwan, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+significance+of+circulating+tumor+cells+in+breast+cancer:+A+review.">The significance of circulating tumor cells in breast cancer: A review.</a> The Breast. 23, 552-560 (2014).</li><li>Wolf, M. J., 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=Endothelial+CCR2+signaling+induced+by+colon+carcinoma+cells+enables+extravasation+via+the+JAK2-Stat5+and+p38MAPK+pathway.">Endothelial CCR2 signaling induced by colon carcinoma cells enables extravasation via the JAK2-Stat5 and p38MAPK pathway.</a> Cancer Cell. 22 (1), 91-105 (2012).</li><li>Hiratsuka, 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=Primary+tumours+modulate+innate+immune+signalling+to+create+pre-metastatic+vascular+hyperpermeability+foci.">Primary tumours modulate innate immune signalling to create pre-metastatic vascular hyperpermeability foci.</a> Nature Communications. 4, 1853 (2013).</li><li>Deguchi, 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=Eritoran+inhibits+S100A8-mediated+TLR4/MD-2+activation+and+tumor+growth+by+changing+the+immune+microenvironment.">Eritoran inhibits S100A8-mediated TLR4/MD-2 activation and tumor growth by changing the immune microenvironment.</a> Oncogene. 35 (19), 1445-1456 (2016).</li><li>Ieguchi, K., 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=ADAM12-cleaved+ephrin-A1+contributes+to+lung+metastasis.">ADAM12-cleaved ephrin-A1 contributes to lung metastasis.</a> Oncogene. 33 (17), 2179-2190 (2014).</li></ol>

Pre-treatment of mice with antibodies, drugs, a high-fat diet or tumor-conditioned medium prior to tumor cell injection is possible. The most difficult step in this assay is the tail vein injection. Incomplete injection results in inconclusive data. The tail vein in C57BL/6 is particularly difficult to identify, resulting in failed injections. Placing the mice on a heating pad (37 &#176;C) helps dilate the tail vein so that injection becomes easier.
This assay uses a large number of (1 x 10<su...

Tumor metastasis accounts for high mortality in cancer-related diseases. From the viewpoint of investigations at the molecular level, metastasis can be divided into multiple steps: tumor initiation at the primary tumor site, primary tumor growth and invasion into surrounding tissues, intravasation, circulation through blood vessels, extravasation at distant organs, and tumor re-growth. Each step involves different sets of molecules/signals1.
Studies to date have been concerned with events occurring in distant organs before the tumor cells start circulating in the blood, which is also known as the pre-metastatic phase2,3,4,5,6. Our mouse model studies revealed that the pre-metastatic phase facilitates lung metastasis by creating long-lasting and low-level inflammatory responses in the lungs. The pre-metastatic phase is characterized by hyperpermeability of themicrovasculature, recruitment of bone marrow derived cells (BMDC), and upregulation of cytokine/chemokine-like molecules including S100A8 and SAA33,4. It has been reported that lysyl oxidase modifies the extracellular matrix in the lungs to recruit BMDCs7. Another report has revealed the importance of Angpt2, MMP3, and MMP10 in the pre-metastatic phase8. In other words, the intricate interactions between primary tumors, bone marrow, and remote organs need to be understood and properly modulated (for instance, by using drugs that target proteins involved in these interactions) to prevent future metastasis9. To regulate the pre-metastatic phase, it should first be visualized and evaluated for diagnostic or therapeutic interventions. Here, we report a lung tumor cell recruitment assay that enables the study of the pre-metastatic phase in the lungs.
Tumor cells directly injected into the blood vessel of the mouse are similar to circulating tumor cells in cancer patients, although there may be differences between cultured cells and circulating tumor cells. Circulating tumor cells themselves undergo some characteristic changes when they enter circulation from the primary tumor. Nevertheless, cultured cells can form tumors in immunodeficient mice when they are injected in the tail vein. Additionally, in the mouse model system, fluorescence labeled tumor cells can be used that allow tracking of these cells in the body. The behavior of circulating tumor cells is critical as they determine the ultimate consequences in cancer patients10. Blood is not a good place for survival of tumor cells2. They need to escape from attack by the host immune system and need anti-apoptotic signals to prevent apoptosis due to a lack of physical support. Tumor cells with higher abilities of tumor initiation at metastatic sites generate more tumor nodules. If the tumor cells show specific organ tropism, metastasis should be observed in those particular organs. In this assay, the initial steps of the metastatic cascade (primary tumor growth and invasion) are not included, and so the focus is on the interaction between circulating tumor cells and the stromal cells (endothelial cells, epithelial cells, and blood cells). In conventional tumor cell injection assays, researchers have to wait until tumor nodules grow to a tangible size to detect the metastasis. In this case, the exact number of tumor cells in the blood vessel cannot be quantified. Additionally, this process includes a tumor regrowth phase, indicating that other factors in the tumor cells may affect the outcome.
Counting labeled tumor cells under a fluorescence stereomicroscope is a simple process. The stereomicroscope provides a wide field of view so that the whole lung can be scanned. Flow cytometry is also a useful tool that instantly gives an accurate number of tumor cells in the tissue. Counting fluorescent cells in the tissue under a confocal microscope is also possible and displays the most accurate pictures of metastatic tumor cells, but it is time-consuming and may give biased results if only a selected area is counted. The ultimate goal of this assay is to observe how easily tumor cells accumulate in the lungs. As reported previously3,4, if the lungs are in pre-metastatic phase due to inflammatory signaling from the primary tumor, the injected tumor cells are prone to accumulate in the lungs, thus implying higher chances of lung metastasis. Other conditions (rheumatoid arthritis, asthma, etc.), and their treatment with anti-inflammatory agents (such as anti-TNF&#945;) may attenuate lung metastasis. Thus, we conclude that this assay is a powerful tool to assess the possibility of lung metastasis.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Collagenase</td>
			<td>Sigma</td>
			<td>C6885</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase</td>
			<td>Gibco</td>
			<td>17105-041</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine serum albumin</td>
			<td>Sigma</td>
			<td>A7030</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>Gibco</td>
			<td>14190-144</td>
			<td>no calcium, no magnesium</td>
		</tr>
		<tr>
			<td>Deoxyribonuclease I</td>
			<td>Sigma</td>
			<td>DN-25</td>
			<td>trace amount</td>
		</tr>
		<tr>
			<td>RBC lysis buffer</td>
			<td>Sigma</td>
			<td>R7757</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell strainer</td>
			<td>BD</td>
			<td>352340</td>
			<td>40 micrometer mesh</td>
		</tr>
		<tr>
			<td>Fluorescence labeling kit</td>
			<td>Sigma</td>
			<td>MIN26-KIT</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>11965-092</td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#956;m syringe filter</td>
			<td>sartorius</td>
			<td>17597K</td>
			<td></td>
		</tr>
		<tr>
			<td>O.C.T. compound</td>
			<td>Sakura Finetek</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde Phosphate Buffer Solution</td>
			<td>Wako</td>
			<td>163-20145</td>
			<td></td>
		</tr>
	</tbody>
</table>

lung tumor cell recruitment assay

To investigate the molecular mechanisms governing tumor metastasis, various assays using the mouse as a model animal have been proposed. Here, we demonstrate a simple assay to evaluate tumor cell extravasation or micrometastasis. In this assay, tumor cells were injected through the tail vein, and after a short period, the lungs were dissected and digested to count the accumulated labeled tumor cells. This assay skips the initial step of primary tumor invasion into the blood vessel and facilitates the study of events in the distant organ where tumor metastasis occurs. The number of cells injected into the blood vessel can be optimized to observe a limited number of metastases. It has been reported that stromal cells in the distant organ contribute to metastasis. Thus, this assay could be a useful tool to explore potential therapeutic drugs or devices for prevention of tumor metastasis.

The lungs present many GFP-LLC cells 2 h after injection (Figure 1A). It should be noted that the fluorescent spots also detected in the red filter should be excluded from the cell number count. The vast majority of LLC cells disappear from the lungs 24 h after injection (Figure 1C).
To confirm the number of the GFP-LLC in the lungs, one of the lobes can be used for flo...

Watch this Scientific Journal Video about Lung Tumor Cell Recruitment Assay at JoVE.com

Lung Tumor Cell Recruitment Assay

This manuscript describes a method to quantify tumor cell accumulation in the lungs in an animal model of tumor metastasis.

To investigate the molecular mechanisms governing tumor metastasis, various assays using the mouse as a model animal have been proposed. Here, we ...

This method can help answer key questions in the tumor biology field about the molecular mechanisms of metastasis. The main advantage of this technique is that the recruitment of tumor cells within a remote organ can be quantitate. Begin by using a non-enzymatic cell dissociation reagent to remove fluorescent protein-expressing Lewis lung carcinoma, or LLC, cells from their culture container according to standard protocols.Transfer the resulting cell solution into a 15-milliliter conical tube before centrifugation, and centrifuge wash the pellets two times in five milliliters of PBS per wash. After the second wash, filter the cells through a 40-micrometer pore cell strainer, and dilute the suspension to a one times 10 to the six cells per milliliter concentration. Then load the cells into a one-milliliter syringe equipped with a 29-gauge needle, and inject 100 microliters of cells into the tail vein of each eight-to-10-week-old, C57-Black-6, male mouse.At the appropriate experimental endpoint, use scissors to remove the skin from the ventral surface of each mouse, and cut the ribs and the diaphragm to expose the thoracic cavity. Use a 25-gauge winged infusion needle and tubing to flush 15 milliliters of PBS through the right ventricle, and remove the heart and the thymus. Gripping the trachea with forceps, pull up, dissecting the connective tissues around the trachea, to harvest the lungs.Then wash the lungs in PBS, and detach one lobe for visualization of the fluorescent cells in situ under a fluorescence microscope. To digest the lung tissue, first dice the caudal lobe with scissors, and place the lung pieces in a 10-milliliter syringe. Close the syringe with the plunger, and aspirate five milliliters of digestion solution into the syringe, moving the plunger in and out of the syringe shaft until the lung tissue is disseminated throughout the solution.Dispense the lung slurry into a 50-milliliter tube, and digest the tissue on a reciprocal shaker for 15 minutes at 37 degrees Celsius and 150 rpm. At the end of the incubation, triturate the remaining tissue until the lung cells are completely dispersed, and return the tube to the shaker for an additional 30 minutes. Then filter the cells through a 40-micrometer pore strainer, and collect the cells by centrifugation.To analyze the isolated lung cells by flow cytometry, resuspend the pellet in two milliliters of red blood cell lysis buffer for one minute at room temperature, and collect the cells by centrifugation. Then centrifuge the pellet two times in five milliliters of fresh PBS supplemented with 1%bovine serum albumin per wash. After the second centrifugation, resuspend the pellet in one milliliter of fresh PBS plus BSA, and filter the cells through a new 40-micrometer pore strainer for quantification of the tumor cells by flow cytometry.The lungs present many GFP-LLC cells two hours after injection, with the vast majority of cells disappearing from the lungs within 24 hours. Note that any fluorescent spots that are detected within the red filter should be excluded from the cell count. To confirm the number of GFP-LLC in the lungs, one of the lobes can be used for flow cytometric analysis as demonstrated.While attempting this procedure, it's important to remember that a frozen section procedure is a more accurate method for observing the exact location of tumor cells.

Research

JoVE Journal

Cancer Research

4.9K ビュー.  Tokyo Women's Medical University. この方法は、転移の分子メカニズムに関する腫瘍生物学分野の重要な質問に答えるのに役立ちます。この技術の主な利点は、遠隔器官内の腫瘍細胞の募集を定量化できることである。まず、非酵素細胞解離試薬を使用して、蛍光タンパク質発現ルイス肺癌(LLC)を、標準的なプロトコルに従って培養容器から細胞を除去することから始めます。得られた細胞溶液を遠?...

ビデオ: Lung Tumor Cell Recruitment Assay

Conditional Knockdown of Gene Expression in Cancer Cell Lines to Study the Recruitment of Monocytes/Macrophages to the Tumor Microenvironment

siRNA and shRNA-mediated knock down (KD) methods of regulating gene expression are invaluable tools for understanding gene and protein function. However, in the case that the KD of the protein of interest has a lethal effect on cells or the anticipated effect of the KD is time-dependent, unconditional KD methods are not appropriate. Conditional systems are more suitable in these cases and have been the subject of much interest. These include Ecdysone-inducible overexpression systems, Cytochrome P-450 induction system1, and the tetracycline regulated gene expression systems. 
The tetracycline regulated gene expression system enables reversible control over protein expression by induction of shRNA expression in the presence of tetracycline. In this protocol, we present an experimental design using functional Tet-ON system in human cancer cell lines for conditional regulation of gene expression. We then demonstrate the use of this system in the study of tumor cell-monocyte interaction.

This protocol serves as a scheme for setting up a functional Tet-ON system in cancer cell lines and its subsequent use, in particular for studying the role of tumor cell-derived proteins in recruitment of monocytes/macrophages to the tumor microenvironment.

siRNA and shRNA-mediated knock down (KD) methods of regulating gene expression are invaluable tools for understanding gene and protein function. However, ...

The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 &#956;M of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.

An animal model is needed to decipher the role of circulating tumor cells (CTCs) in promoting lung colonization during cancer metastasis. Here, we established and successfully performed an in vivo assay to specifically test the requirement of polymeric fibronectin (polyFN) assembly on CTCs for lung colonization.

Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by ...

Acellular and Cellular Lung Model to Study Tumor Metastasis

It is difficult to isolate tumor cells at different points of tumor progression. We created an ex vivo lung model that can show the interaction of tumor cells with a natural matrix and continual flow of nutrients, as well as a model that shows the interaction of tumor cells with normal cellular components and a natural matrix. The acellular ex vivo lung model is created by isolating a rat heart-lung block and removing all the cells using the decellularization process. The right main bronchus is tied off and tumor cells are placed in the trachea by a syringe. The cells move and populate the left lung. The lung is then placed in a bioreactor where the pulmonary artery receives a continual flow of media in a closed circuit. The tumor grown on the left lung is the primary tumor. The tumor cells that are isolated in the circulating media are circulating tumor cells and the tumor cells in the right lung are metastatic lesions. The cellular ex vivo lung model is created by skipping the decellularization process. Each model can be used to answer different research questions.

Here, we present a protocol for an ex vivo lung cancer model that mimics the steps of tumor progression and helps to isolate a primary tumor, circulating tumor cells, and metastatic lesions.

It is difficult to isolate tumor cells at different points of tumor progression. We created an ex vivo lung model that can show the interaction of tumor ...

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include rapid proliferation and pervasive invasion into the normal brain. Recurrence is thought to result from the presence of radio- and chemo-resistant brain tumor stem cells (BTSCs) that invade away from the initial cancerous mass and, thus, evade surgical resection. Hence, therapies that target BTSCs and their invasive abilities may improve the otherwise poor prognosis of this disease. Our group and others have successfully established and characterized BTSC cultures from GBM patient samples. These BTSC cultures demonstrate fundamental cancer stem cell properties such as clonogenic self-renewal, multi-lineage differentiation, and tumor initiation in immune-deficient mice. In order to improve on the current therapeutic approaches for GBM, a better understanding of the mechanisms of BTSC migration and invasion is necessary. In GBM, the study of migration and invasion is restricted, in part, due to the limitations of existing techniques which do not fully account for the in vitro growth characteristics of BTSCs grown as neurospheres. Here, we describe rapid and quantitative live-cell imaging assays to study both the migration and invasion properties of BTSCs. The first method described is the BTSC migration assay which measures the migration toward a chemoattractant gradient. The second method described is the BTSC invasion assay which images and quantifies a cellular invasion from neurospheres into a matrix. The assays described here are used for the quantification of BTSC migration and invasion over time and under different treatment conditions.

Here, we describe live-cell imaging techniques to quantitatively measure the migration and invasion of glioblastoma brain tumor stem cells over time and under multiple treatment conditions.

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include ...

Digital Polymerase Chain Reaction Assay for the Genetic Variation in a Sporadic Familial Adenomatous Polyposis Patient Using the Chip-in-a-tube Format

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as tumors. Because digital polymerase chain reactions (PCR) enable the precise quantification of DNA copy number variants, they are becoming an essential tool for detecting rare genetic variations, such as drug-resistant mutations. It is expected that molecular diagnoses using digital PCR (dPCR) will be available in clinical practice in the near future; thus, how to efficiently conduct dPCR with human genetic material is a hot topic. Here, we introduce a method to detect Adenomatous polyposis coli (APC) somatic mosaicism using dPCR with the chip-in-a-tube format, which allows eight dPCR reactions to be simultaneously conducted. Care should be taken when filling and sealing the reaction mixture on the chips. This article demonstrates how to avoid the over- and underestimation of positive partitions. Furthermore, we present a simple procedure for collecting the dPCR product from the partitions on the chips, which can then be used to confirm the specific amplification. We hope that this methods report will help promote the dPCR with the chip-in-a-tube method in genetic research.

Digital polymerase chain reaction (PCR) is a useful tool for the high-sensitivity detection of single nucleotide variants and DNA copy number variants. Here, we demonstrate key considerations for measuring rare variants in the human genome using digital PCR with the chip-in-a-tube format.

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as ...

Mesenchymal Stem Cell Isolation from Pulp Tissue and Co-Culture with Cancer Cells to Study Their Interactions

Cancer as a multistep process and complicated disease is not only regulated by individual cell proliferation and growth but also controlled by tumor environment and cell-cell interactions. Identification of cancer and stem cell interactions, including changes in extracellular environment, physical interactions, and secreted factors, might enable the discovery of new therapy options. We combine known co-culture techniques to create a model system for mesenchymal stem cells (MSCs) and cancer cell interactions. In the current study, dental pulp stem cells (DPSCs) and PC-3 prostate cancer cell interactions were examined by direct and indirect co-culture techniques. Condition medium (CM) obtained from DPSCs and 0.4 &#181;m pore sized trans-well membranes were used to study paracrine activity. Co-culture of different cell types together was performed to study direct cell-cell interaction. The results revealed that CM increased cell proliferation and decreased apoptosis in prostate cancer cell cultures. Both CM and trans-well system increased cell migration capacity of PC-3 cells. Cells stained with different membrane dyes were seeded into the same culture vessels, and DPSCs participated in a self-organized structure with PC-3 cells under this direct co-culture condition. Overall, the results indicated that co-culture techniques could be useful for cancer and MSC interactions as a model system.

We provide protocols for evaluation of mesenchymal stem cells isolated from dental pulp and prostate cancer cell interactions based on direct and indirect co-culture methods. Condition medium and trans-well membranes are suitable to analyze indirect paracrine activity. Seeding differentially stained cells together is an appropriate model for direct cell-cell interaction.

Cancer as a multistep process and complicated disease is not only regulated by individual cell proliferation and growth but also controlled by tumor ...

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 ...

Semi-automatic PD-L1 Characterization and Enumeration of Circulating Tumor Cells from Non-small Cell Lung Cancer Patients by Immunofluorescence

Circulating tumor cells (CTCs) derived from the primary tumor are shed into the bloodstream or lymphatic system. These rare cells (1&#8722;10 cells per mL of blood) warrant a poor prognosis and are correlated with shorter overall survival in several cancers (e.g., breast, prostate and colorectal). Currently, the anti-EpCAM-coated magnetic bead-based CTC capturing system is the gold standard test approved by the U.S. Food and Drug Administration (FDA) for enumerating CTCs in the bloodstream. This test is based on the use of magnetic beads coated with anti-EpCAM markers, which specifically target epithelial cancer cells. Many studies have illustrated that EpCAM is not the optimal marker for CTC detection. Indeed, CTCs are a heterogeneous subpopulation of cancer cells and are able to undergo an epithelial-to-mesenchymal transition (EMT) associated with metastatic proliferation and invasion. These CTCs are able to reduce the expression of cell surface epithelial marker EpCAM, while increasing mesenchymal markers such as vimentin. To address this technical hurdle, other isolation methods based on physical properties of CTCs have been developed. Microfluidic technologies enable a label-free approach to CTC enrichment from whole blood samples. The spiral microfluidic technology uses the inertial and Dean drag forces with continuous flow in curved channels generated within a spiral microfluidic chip. The cells are separated based on the differences in size and plasticity between normal blood cells and tumoral cells. This protocol details the different steps to characterize the programmed death-ligand 1 (PD-L1) expression of CTCs, combining a spiral microfluidic device with customizable immunofluorescence (IF) marker set.

The characterization of circulating tumor cells (CTCs) is a popular topic in translational research. This protocol describes a semi-automatic immunofluorescence (IF) assay for PD-L1 characterization and enumeration of CTCs in non-small cell lung cancer (NSCLC) patient samples.

Circulating tumor cells (CTCs) derived from the primary tumor are shed into the bloodstream or lymphatic system. These rare cells (1&#8722;10 cells per mL ...

In Vitro Assay to Study Tumor-macrophage Interaction

Tumor associated macrophages (TAMs) account for a large percentage of cells in the tumor mass for different types of cancers. Glioblastoma (GBM), a malignant brain tumor with no cure, has up to a half the tumor mass TAMs. TAMs can be pro-tumoral or anti-tumoral, depending on the activation of specific genes in the cells. Genetic mutations in the tumors, through regulating cytokine expression, can affect recruitment of TAMs to the tumor microenvironment. Here, we describe a quantitative cell-based assay to assess macrophage recruitment by the conditioned medium from the tumor cells. This assay uses the human macrophage cell line MV-4-11 to study macrophage attraction by the conditioned medium from glioblastoma, allowing for high reproducibility and low variability. Data generated with this assay can contribute to a better understanding of the interaction between the tumor and the tumor microenvironment. Similar assay can be used to assess interaction between the tumor cells and other immune cells, including T cells and natural killer (NK) cells.

This article represents a useful in vitro assay to evaluate the capability of conditioned medium from tumor cells to attract macrophages.

Tumor associated macrophages (TAMs) account for a large percentage of cells in the tumor mass for different types of cancers. Glioblastoma (GBM), a ...

Detection of Lung Tumor Progression in Mice by Ultrasound Imaging

With ~1.6 million victims per year, lung cancer contributes tremendously to the worldwide burden of cancer. Lung cancer is partly driven by genetic alterations in oncogenes such as the KRAS oncogene, which constitutes ~25% of lung cancer cases. The difficulty in therapeutically targeting KRAS-driven lung cancer partly stems from having poor models that can mimic the progression of the disease in the lab. We describe a method that permits the relative quantification of primary KRAS lung tumors in a Cre-inducible LSL-KRAS G12D mouse model via ultrasound imaging. This method relies on brightness (B)-mode acquisition of the lung parenchyma. Tumors that are initially formed in this model are visualized as B-lines and can be quantified by counting the number of B-lines present in the acquired images. These would represent the relative tumor number formed on the surface of the mouse lung. As the formed tumors develop with time, they are perceived as deep clefts within the lung parenchyma. Since the circumference of the formed tumor is well-defined, calculating the relative tumor volume is achieved by measuring the length and width of the tumor and applying them in the formula used for tumor caliper measurements. Ultrasound imaging is a non-invasive, fast and user-friendly technique that is often used for tumor quantifications in mice. Although artifacts may appear when obtaining ultrasound images, it has been shown that this imaging technique is more advantageous for tumor quantifications in mice compared to other imaging techniques such as computed tomography (CT) imaging and bioluminescence imaging (BLI). Researchers can investigate novel therapeutic targets using this technique by comparing lung tumor initiation and progression between different groups of mice.

This protocol describes the steps taken to induce KRAS lung tumors in mice as well as the quantification of formed tumors by ultrasound imaging. Small tumors are visualized in early timepoints as B-lines. At later timepoints, relative tumor volume measurements are achieved by the measurement tool in the ultrasound software.

With ~1.6 million victims per year, lung cancer contributes tremendously to the worldwide burden of cancer. Lung cancer is partly driven by genetic ...