Inactivation of XPF Sensitizes Cancer Cells to Gemcitabine

Figure 2

XPF is epistatic to APE in the gemcitabine resistance. The expression of XPF and/or APE was suppressed by siRNAs in HeLa cells and the cellular sensitivity to gemcitabine was examined. XPF- or APE-suppressed HeLa cells (closed square and closed triangle, respectively) showed sensitivity to gemcitabine. Cosuppression of XPF and APE (closed circle with dashed line) resulted in the sensitivity to gemcitabine similar to the sensitivity induced by the suppression of XPF or APE individually. A control siRNA (siControl) was used as a control (open diamond). Three independent experiments were performed and averages of surviving fraction are plotted. The error bars show standard deviations. The differences in the gemcitabine sensitivity between the control cells and the cells treated with siXPF, siAPE, or siXPF+siAPE are statistically significant at 10 nM and 50 nM with p<0.05. The western blots showed a significant suppression of XPF (more than 95%) and ~75% reduction in the expression of APE with the siRNA treatment. The cosuppression experiments with two siRNAs, siXPF and siAPE, resulted in similar levels of suppression of each protein induced by individual siRNA (more than 95% reduction in XPF and ~85% reduction in APE). Tubulin was used as a protein loading control.

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