PML silencing inhibits cell proliferation and induces DNA damage in cultured ovarian cancer cells

The promyelocytic leukemia (PML) gene is a tumor suppressor gene. It was first identified in acute promyelocytic leukemia, in which it is fused to retinoic acid receptor α by the (15;17) chromosomal translocation. The function of the PML protein is frequently lost or aberrant in human solid tumors. In human ovarian carcinoma tissue, PML detected by immunohistochemistry was highly expressed. A PML-silencing vector, pSRG-shPml, was constructed and used to transfect human ovarian cancer cells. Cells were cultured and selected with puromycin for 10-15 days, and then the PML mRNA expression levels were detected by RT-qPCR and immunofluorescence. Proliferation and clone number of PML-depleted cells were detected using MTT assay and colony-forming assay. The protein expression associated with DNA damage and apoptosis was assessed in PML-depleted cells using western blot analysis and immunofluorescence. The results showed that PML was highly expressed in human ovarian tissue. The proliferation and colony formation of ovarian cancer cells were significantly inhibited after PML was depleted. Western blot analysis and immunofluorescence revealed that p-H2AX and cleaved caspase-3 expression significantly increased after PML silencing. PML was located in the nucleus, and it formed foci after X-ray irradiation. PML foci increased significantly with increasing irradiation doses.