Characterization of cervical cancer stem cell-like cells: phenotyping, stemness, and human papilloma virus co-receptor expression

Cancer stem cells (CSC) exhibit high tumorigenic capacity in several tumor models. We have now determined an extended phenotype for cervical cancer stem cells. Our results showed increased CK-17, p63(+), AII(+), CD49f(+) expression in these cells, together with higher Aldehyde dehydrogenase (ALDH(bright))activity in Cervical CSC (CCSC) enriched in cervospheres. An increase in stem cell markers, represented by OCT-4, Nanog, and β-catenin proteins, was also observed, indicating that under our culture conditions, CCSC are enriched in cervospheres, as compared to monolayer cultures. In addition, we were able to show that an increased ALDH(bright) activity correlated with higher tumorigenic activity. Flow cytometry and immunflorescence assays demonstrated that CCSC in cervosphere cultures contain a sub-population of cells that contain Annexin II, a Human papillomavirus (HPV) co-receptor. Taken together, under our conditions there is an increase in the number of CCSC in cervosphere cultures which exhibit the following phenotype: CK-17, p63(+), AII(+), CD49f(+) and high ALDH activity, which in turn correlates with higher tumorigenicity. The presence of Annexin II and CD49f in CCSC opens the possibility that normal cervical stem cells could be the initial target of infection by high risk HPV.