Spheres from cervical cancer cells display stemness and cancer drug resistance.

Abstract

Cervical cancer is one of the most common gynecological malignant tumors and is the cause of a serious health problem worldwide. An increasing amount of evidence has shown that cancer stem cells (CSCs) are present in tumors, and that these CSCs may be responsible for tumor metastasis and relapse. The present study aimed to identify and characterize a CSC population from the CaSki cell line. First, a stem cell culture medium was used to selectively expand the cancer stem-like cell spheres, and the putative stemness markers, Oct4 and Sox2, were identified. These markers were all highly expressed in the CaSki sphere-forming cells. Next, target region amplified polymorphism-polymerase chain reaction was performed and the CaSki sphere-forming cells were found to exhibit higher telomerase activity than the CaSki control cells cultured in non-stem cell medium. Using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, it was found that the CaSki sphere-forming cells were more resistant to chemotherapeutic drugs than the control CaSki cells. Using the tumor invasive assay, it was shown that the CaSki sphere-forming cells were more invasive than the control CaSki cells. These characteristics all suggested that the tumor sphere-forming cells mirrored the acknowledged CSC phenotypes. Overall, the use of a suspended sphere culture of CaSki cells may be an easy and feasible approach for enriching cancer stem-like cells in cervical cancer research.