Clonal analysis of cancer cells that survived anticancer drug treatment

We hypothesized that postchemotherapeutic recurrent cancer cells consist of sensitive cells and resistant cells. To examine this hypothesis, the clonality of the postchemotherapeutic surviving cancer cells was characterized. The postchemotherapeutic surviving cancer cells was established using a human cervical carcinoma cell line, ME180, in which cells were treated with either SN38, VP16, or THP for more than 8 weeks. The surviving cells were subcloned by limiting dilutions yielding the following cloning efficiencies: 18% for SN38, 26% for VP16, and 57% for THP. Characterization of the established subclones proved that the postchemotherapeutic recurrent cancer cells consisted of both sensitive cancer cells and resistant cancer cells. This result supports the hypothesis and hence points toward improvement of chemotherapeutic effect through an understanding of the dual types of surviving cells.