Serene Samyesudhas and Dr. Lynn Roy assisted in preparing samples for filming.

1. Cell Culture and Fluorescent Labeling of Ovarian Cancer Cell Lines
<ol>
	<li>Prepare SKOV3 media: McCoy media supplemented with 10% fetal bovine serum (FBS), 0.1 mM L-glutamine, 50 U/ml penicillin, and 50 &#956;g/ml streptomycin. Maintain OVCA429 cells in minimal essential media (MEM) supplemented with 10% FBS, 1 mM sodium pyruvate, 0.1 mM L-glutamine, 50 U/ml penicillin, and 50 &#956;g/ml streptomycin.</li>
	<li>Propagate SKOV3 and OVCA429 cell lines in a humidified incubator at 37 &#176;C with 5% CO2. G...

<ol>
	<li>Pennington, K., Pulaski, H., Pennington, M., Liu, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Too+Much+of+a+Good+Thing:+Suicide+Prevention+Promotes+Chemoresistance+in+Ovarian+Carcinoma.">Too Much of a Good Thing: Suicide Prevention Promotes Chemoresistance in Ovarian Carcinoma.</a> Curr Cancer Drug Targets. 10, 575-583 (2010).</li><li>Thigpen, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rational+approach+to+the+management+of+recurrent+or+persistent+ovarian+carcinoma.">A rational approach to the management of recurrent or persistent ovarian carcinoma.</a> Clin Obstet Gynecol. 55, 114-130 (2012).</li><li>Burgos-Ojeda, D., Rueda, B. R., Buckanovich, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovarian+cancer+stem+cell+markers:+prognostic+and+therapeutic+implications.">Ovarian cancer stem cell markers: prognostic and therapeutic implications.</a> Cancer letters. 322, 1-7 (2012).</li><li>Ma, L., Lai, D., Liu, T., Cheng, W., Guo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+stem-like+cells+can+be+isolated+with+drug+selection+in+human+ovarian+cancer+cell+line+SKOV3.">Cancer stem-like cells can be isolated with drug selection in human ovarian cancer cell line SKOV3.</a> Acta Biochim Biophys Sin (Shanghai). 42, 593-602 (2010).</li><li>Bonnet, D., Dick, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+acute+myeloid+leukemia+is+organized+as+a+hierarchy+that+originates+from+a+primitive+hematopoietic+cell.">Human acute myeloid leukemia is organized as a hierarchy that originates from a primitive hematopoietic cell.</a> Nature Medicine. 3, 730-737 (1997).</li><li>Alison, M. R., Lim, S. M., Nicholson, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+stem+cells:+problems+for+therapy.">Cancer stem cells: problems for therapy.</a> The Journal of pathology. 223, 147-161 (2011).</li><li>Luo, X., Dong, Z., Chen, Y., Yang, L., Lai, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enrichment+of+ovarian+cancer+stem-like+cells+is+associated+with+epithelial+to+mesenchymal+transition+through+an+miRNA-activated+AKT+pathway.">Enrichment of ovarian cancer stem-like cells is associated with epithelial to mesenchymal transition through an miRNA-activated AKT pathway.</a> Cell proliferation. 46, 436-446 (2013).</li><li>Wang, L., Mezencev, R., Bowen, N. J., Matyunina, L. V., McDonald, J. F. <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+stem-like+cells+from+a+human+ovarian+cancer+cell+line.">Isolation and characterization of stem-like cells from a human ovarian cancer cell line.</a> Molecular and cellular biochemistry. 363, 257-268 (2012).</li><li>Abubaker, 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=Short-term+single+treatment+of+chemotherapy+results+in+the+enrichment+of+ovarian+cancer+stem+cell-like+cells+leading+to+an+increased+tumor+burden.">Short-term single treatment of chemotherapy results in the enrichment of ovarian cancer stem cell-like cells leading to an increased tumor burden.</a> Molecular cancer. 12, 24 (2013).</li><li>Conic, I., Dimov, I., Tasic-Dimov, D., Djordjevic, B., Stefanovic, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovarian+epithelial+cancer+stem+cells.">Ovarian epithelial cancer stem cells.</a> ScientificWorldJournal. 11, 1243-1269 (2011).</li><li>Liu, K. 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=Ovarian+cancer+stem-like+cells+show+induced+translineage-differentiation+capacity+and+are+suppressed+by+alkaline+phosphatase+inhibitor.">Ovarian cancer stem-like cells show induced translineage-differentiation capacity and are suppressed by alkaline phosphatase inhibitor.</a> Oncotarget. 4 (12), 2366-2382 (2013).</li><li>Liu, T., Cheng, W., Lai, D., Huang, Y., Guo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+primary+ovarian+cancer+cells+in+different+culture+systems.">Characterization of primary ovarian cancer cells in different culture systems.</a> Oncology reports. 23, 1277-1284 (2010).</li></ol>

The authors declare they have no competing financial interest.

CSCs that are resistant to therapy may be accountable for relapse after treatment of primary tumor. Characterization of CSCs may lead to improved therapies for ovarian cancer. The critical parameters in the establishment of chemoresistant CSCs using the above protocol are timing the length of treatment with chemotherapy and the concentration of chemotherapy. When using the protocol in Ma et al. it was found that after 7 days of treatment with cisplatin and paclitaxel, no viable cells remained4. By red...

Resistance to chemotherapy is a major impediment to the treatment and cure of cancer. Ovarian cancer is the 5th leading cause of cancer-related deaths among women in the United States (American Cancer Society Facts and Figures 2013). Patients initially respond well to chemotherapy, but most patients relapse1. After relapse patients are treated with a variety of additional chemotherapy agents with very little benefit2. General properties of CSCs include unlimited proliferative capabilities, retention of an undifferentiated state, resistance to drug treatment, efficient DNA repair, and ability to generate malignant tumor cells with different phenotypes3. CSCs frequently exhibit expression of stem cell genes such as Nanog, Oct4, Sox2, Nestin, CD133, and CD117. CSCs often express elevated levels of ABCG2, and ALDH genes that may contribute to drug efflux and metabolism3,4. 
The first definitive evidence for CSCs was demonstrated by isolating acute myeloid leukemia-initiating cells that were capable of self-renewal and tumor generation5. These leukemic stem cells expressed surface CD34 and generated leukemia in NOD/SCID (immunocompromised) mice5. Since then CSCs have been identified in many cancer types including leukemias/lymphomas, breast, bladder, colorectal, endometrial, sarcomas, hepatocellular carcinoma, melanomas, gliomas, ovarian, pancreatic, prostate, squamous cell carcinoma, and lung6. Therefore, being able to study this subtype of cancer cell is advantageous.
The goal of this study is to create a protocol for the selection and isolation of chemoresistant CSCs. Several methods have been reported for the isolation of CSCs from ovarian cancer cell lines. Non-adherent spheroids isolated from OVCAR-3, SKOV3, or HO8910 cultures demonstrate stem-like properties7,8. Isolation of CD133+ cells from OVCAR-3 cultures also yields CSCs. CSCs have also been selected in culture by treatment with chemotherapeutic agents. Treating tumor cell lines (OVCA433, Hey, and SKOV3 cells) with cisplatin and paclitaxel allows for the expansion and isolation of CSCs4,9. While culture of some cell types in CSC media leads to isolation of CSCs, SKOV3 cells did not survive culture in serum-free media or form sphere cells4. Therefore, treatment of cells with cisplatin and paclitaxel aided the expansion or isolation of this population4.
Using a modification of the procedure presented by Ma and colleagues4 we developed a method to isolate CSCs from the ovarian cancer cell lines. Our protocol is advantageous as it yields more viable cells while using less toxic chemotherapeutic agents. Cells are treated with cisplatin and subsequently grown in serum-free media supplemented with growth factors (stem cell media). We isolate the resulting non-adherent sphere cells and assay them for their expression of stem cell markers. This model enables the study of CSC properties and response to drug therapy.

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enrichment for chemoresistant ovarian cancer stem cells from human cell lines

Cancer stem cells (CSCs) are defined as a subset of slow cycling and undifferentiated cells that divide asymmetrically to generate highly proliferative, invasive, and chemoresistant tumor cells. Therefore, CSCs are an attractive population of cells to target therapeutically. CSCs are predicted to contribute to a number of types of malignancies including those in the blood, brain, lung, gastrointestinal tract, prostate, and ovary. Isolating and enriching a tumor cell population for CSCs will enable researchers to study the properties, genetics, and therapeutic response of CSCs. We generated a protocol that reproducibly enriches for ovarian cancer CSCs from ovarian cancer cell lines (SKOV3 and OVCA429). Cell lines are treated with 20 &#181;M cisplatin for 3 days. Surviving cells are isolated and cultured in a serum-free stem cell media containing cytokines and growth factors. We demonstrate an enrichment of these purified CSCs by analyzing the isolated cells for known stem cell markers Oct4, Nanog, and Prom1 (CD133) and cell surface expression of CD177 and CD133. The CSCs exhibit increased chemoresistance. This method for isolation of CSCs is a useful tool for studying the role of CSCs in chemoresistance and tumor relapse.

To demonstrate that we isolated CSCs from epithelial ovarian cancer cell lines using cisplatin treatment, we first acquired images of the cell lines prior to treatment and after selection. We used light microscopy to capture images of adherent (untreated) SKOV3 and OVCA429 cells and SKOV3 and OVCA429 CSCs (Figure 1). CSCs appear round and not attached to the tissue culture plates (Figures 1 and 2). We further show that SKOV3 cells transduced with RFP retain their fluores...

Watch this Scientific Journal Video about Enrichment for Chemoresistant Ovarian Cancer Stem Cells from Human Cell Lines at JoVE.com

Enrichment for Chemoresistant Ovarian Cancer Stem Cells from Human Cell Lines

Cancer stem cells (CSCs) are&#160;implicated in tumor relapse due to chemoresistance. We have optimized a protocol for selection and expansion of CSCs from ovarian cancer cell lines. By treating cells with the chemotherapeutic cisplatin and culturing&#160;in a stem cell promoting media we enrich for non-adherent CSC cultures.

Cancer stem cells (CSCs) are defined as a subset of slow cycling and undifferentiated cells that divide asymmetrically to generate highly proliferative, ...

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13.4K Views.  Indiana University School of Medicine. Cancer stem cells (CSCs) are implicated in tumor relapse due to chemoresistance. We have optimized a protocol for selection and expansion of CSCs from ovarian cancer cell lines. By treating cells with the chemotherapeutic cisplatin and culturing in a stem cell promoting media we enrich for non-adherent CSC cultures.