Radiotherapy is promising and effective for treating prostate cancer but the addition of a tumor cell radiosensitizer would improve therapeutic outcomes. PC-1/ PrLZ, a TPD52 protein family member is frequently upregulated in advanced prostate cancer cells and may be a biomarker of aggressive prostate cancer. Therefore, we investigated the potential role of PC-1/PrLZ for increasing radioresistance in human prostate cancer cell lines. Growth curves and survival assays after g-ray irradiation confirmed that depletion of endogenous PC-1/PrLZ significantly increased prostate cancer cell radiosensitivity. Irradiation (IR) increased PC-1/PrLZ expression in a doseand time-dependent manner and increased radiosensitivity in PC-1/PrLZ-suppressed cells was partially due to decreased DNA double strand break (DBS) repair which was measured with comet and gH2AX foci assays. Furthermore, depletion of PC-1/PrLZ impaired the IR-induced G2/M checkpoint, which has been reported to be correlate with radioresistance in cancer cells. PC-1/PrLZ-deficient cells exhibited higher level of autophagy when compared with control cells. Thus, specific inhibition of PC-1/PrLZ might provide a novel therapeutic strategy for radiosensitizing prostate cancer cells.
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