Zinc induces apoptosis on cervical carcinoma cells by p53-dependent and -independent pathway.

OBJECTIVE: There is evidence that the mineral zinc is involved in the apoptotic cell death of various carcinoma cells. In this study, we aim to determine whether zinc in the form of CIZAR induces apoptosis in cervical carcinoma cells by increasing intracellular zinc concentration. STUDY DESIGN: CaSki and HeLa cervical carcinoma cells and HPV-16 DNA-transformed keratinocyte (CRL2404) were treated with different concentrations of CIZAR. The cell viability test was carried out, the intracellular level of zinc was determined, and apoptosis was confirmed by flow cytometry after propidium iodide (PI) staining and fluorescence microscopy under DAPI staining. The expression of cell-cycle regulators was analyzed by Western blot, including the knock down of p53 and expression of HPV E6 and E7 genes by RT-PCR. RESULTS: Intracellular zinc accumulation induced the down-regulation of E6/E7 proteins through targeting of the specific transcriptional factors in the upstream regulatory region. p53 was induced after CIZAR treatment and p53-dependent apoptosis did not occur after knock down by p53 siRNA. In cervical carcinoma cells, regardless of HPV-infection, CIZAR induces apoptosis by the activation of the p53-independent pathways through the up-regulation of p21waf1, the down-regulation of c-Myc, and by decreasing the Bcl-2/Bax ratio. CONCLUSIONS: CIZAR induces apoptosis not only through the restoration of p53/Rb-dependent pathways in HPV-positive cells, but also through the activation of p53/Rb-independent pathways and the mitochondrial death-signal pathway in cervical carcinoma cells regardless of HPV-infection.

Antiproliferative and apoptotic effects of zinc-citrate compound (CIZAR(R)) on human epithelial ovarian cancer cell line, OVCAR-3.

OBJECTIVE: Zinc inhibits the growth of several carcinoma cells through induction of cell cycle arrest and apoptosis. The intracellular concentration of zinc and its dynamic changes are critically important in cell biology. We investigated the effects of zinc-citrate compound (CIZAR) on normal human ovarian epithelial cells (NOSE) and human epithelial ovarian cancer cell line, OVCAR-3. METHODS: To investigate the potential effect of CIZAR on cell growth and survival, cells were treated with different doses and exposed to different times. Intracellular concentration of zinc was measured by colorimetric assay. Mitochondrial aconitase activity was determined in cell extracts using aconitase assay. The flow cytometric assay, DNA laddering, and morphological analysis were done to investigate cytotoxic effects of CIZAR. Molecular mechanism of cell death was investigated by p53, Bcl-xL, Bcl-2, Bax protein, activity of caspase-3 and -12, and activity of telomerase. RESULTS: CIZAR-induced zinc accumulation in OVCAR-3 cells was higher than that in NOSE cells. CIZAR(R) treatment resulted in a time- and dose-dependent decrease in cell number in OVCAR-3 cells in comparison with NOSE cells. M-aconitase activity was significantly decreased in OVCAR-3 cells within 4 h exposure to CIZAR but relatively constant in NOSE cells. The flow cytometric assay, DNA laddering, and morphological analysis indicated apoptosis in OVCAR-3 cells but not in NOSE cells. CIZAR increased the expression of p21(waf1) which is a part of p53-independent pathway and induced reduction of telomerase activity. CIZAR reduced expression of Bcl-2 and Bcl-xL proteins but induced expression of Bax protein. CIZAR induced apoptosis of OVCAR-3 cells by activation of caspase-12 and caspase-3 pathway. CONCLUSIONS: Exposure to CIZAR induces apoptosis in OVCAR-3 cells which accumulate high intracellular levels of zinc, but not in NOSE cells, which do not accumulate high levels of zinc. CIZAR(R) prevents the proliferation of OVCAR-3 cells by inactivation of m-aconitase activity and induces apoptosis by induction of proapoptotic gene (Bax), repression of antiapoptotic genes (Bcl-2, Bcl-xL), and consequently activation of caspase-3. CIZAR also induced activation of caspase-12. The CIZAR will offer new window in prevention and treatment of epithelial ovarian cancer.

Necrotic cell death of ovarian adenocarcinoma caused by seminal plasma.

OBJECTIVE: From the knowledge of risk factors of epithelial ovarian cancer, we deduced a hypothesis that human seminal plasma (HSP) has a preventive role in the development of epithelial ovarian cancer. To examine whether HSP directly influences the growth of ovarian cancer, we have investigated the in vitro and in vivo effect of HSP on ovarian adenocarcinoma cell lines (SK-OV-3 and OVCAR-3) in comparison with its effects on normal ovarian surface epithelial cells (NOSE). METHODS: Cell viability was determined by MTT assay. Cytotoxic effect was evaluated by flow cytometry analysis, by DNA laddering, and by morphological analysis. In vivo therapeutic effect of HSP was evaluated by the subcutaneous inoculation of SK-OV-3 cells in nude mice (BALB-c) model. RESULTS: HSP at a final concentration of 1:50 induced a time- and dose-dependent inhibition of SK-OV-3 and OVCAR-3 growth, whereas NOSE was not affected. Flow cytometric analysis, DNA laddering, and morphological analysis indicated that HSP induced necrosis, rather than apoptosis, of both ovarian carcinoma cell lines. In in vivo experiment that used the nude mice (Balb-C) with tumor inoculation of SK-OV-3 cells, HSP induced necrosis of tumor with no detectable toxic effects on the major organs. CONCLUSION: These results show that HSP inhibits the growth and induces the necrosis of epithelial ovarian cancer cells and suggests that one or more components of HSP may provide a scientific basis for preventing epithelial ovarian cancer.