Isolation and Interrogation of Ovarian Cancer Stem Cells
Brendan Ffrench, Michael Gallagher, Aoife Cooke, Britta Stordal, Sharon O'Toole, Orla Sheils, John O'Leary. Trinity College Dublin, Dublin, Ireland
Background: Mice tumourgenicity studies identify cancer stem cells (CSCs) as the founding cells of tumours. CSCs have also been linked to chemoresistance, metastasis and disease relapse. Therapeutically targeting CSCs could remove the tumours malignant potential and circumvent chemoresistance, relapse and metastasis. There is no standardised way to isolate CSCs. Researchers tend to pick one technique and fail to comment on other approaches.
Disease progression of Ovarian Cancer correlates with the predictions of the cancer stem cell hypothesis. For this reason ovarian malignancy was chosen as a system in which to study CSCs, with the intention of understanding the variation of CSCs markers reported in the literature and to further understanding of the various aspects of ovarian malignancy.
Design: Six models of various stages of ovarian malignancy and one model of non-malignant ovarian surface epithelium were screened for the presence of CSCs and somatic stem cells respectively.
Three flow cytometry based CSC screens were implemented; ALDEFLUOR, Hoechst Side-Population and Cell Surface Protein Assays. Cells of interest were isolated via Fluoresence-Assisted Cell Sorting.
Carboplatin and Paclitaxel chemoresistance assays were carried out over 48 – 60 h. Cell viability was measured via MTT assay.
Results: Each screening technique identified putative CSCs (pCSCs) in one or more model systems. For any one model system only one of the three screens identified a pCSC population.
Two of these cell lines have been sorted into their pCSC and non-pCSC subpopulations. In both cases the pCSCs were able to regenerate the non-pCSC phenotype. It was noted that for confident proof of such asymmetric division, single cell plating is required.
There was no difference in chemoresistance between pCSCs and non-pCSCs in either cell line. Both sub-populations were isolated from chemoresistant cell lines.
Conclusions: The various techniques for isolation of CSCs do not mark the same cells within an ovarian cancer context. Each 'type' of ovarian cancer stem cells appears to be mutually exclusive. This may reflect different stages histologies of ovarian disease.
pCSCs have been identified within chemosensitive cell lines, and work is in progress to isolate these sub-populations. Investigation of the differences between these chemoresistance and chemosensitive cancer stem cells could elucidate the mechanisms behind chemoresistant relapse.
Category: Gynecologic & Obstetrics
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 210, Wednesday Afternoon