PK11195 enhances chemosensitivity to cisplatin and paclitaxel in human endometrial and ovarian cancer cells

The potential anticancer agent 1-(2-chlorophenyl-N-methylpropyl)-3-isoquinolinecarboxamide (PK11195), a translocator protein ligand, facilitates the induction of cell death by a variety of cytotoxic and chemotherapeutic agents in various human tumor cell lines. The purpose of this study was to elucidate the effect of PK11195 on three endometrial cancer cell lines, two ovarian cancer cell lines and normal human endometrial epithelial cells. Endometrial and ovarian cancer cells were treated with various concentrations of PK11195 alone or in combination with chemotherapeutic drugs (cisplatin, paclitaxel), and its effect on cell growth, the cell cycle, apoptosis and related measurements was investigated. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that all endometrial and ovarian cancer cell lines were sensitive to the growth-inhibitory effect of PK11195, although normal endometrial epithelial cells were viable after treatment with the same doses of PK11195 that induced growth inhibition in endometrial and ovarian cancer cells. Synergistic anti-neoplastic effects were obtained by a combination of PK11195 with cytostatic drugs. Induction of apoptosis was confirmed by annexin V staining of externalized phosphatidylserine and loss of the transmembrane potential of mitochondria. This induction occurred in concert with altered expression of genes related to apoptosis. These results suggest that PK11195 alone or in combination with chemotherapeutic drugs might be a new therapeutic option for the treatment of endometrial and ovarian cancers.