Cytotoxic Effect of Zinc–Citrate Compound on Choriocarcinoma Cell Lines

This study investigated the cytotoxic effect of zinc–citrate compound (CIZAR®) on choriocarcinoma cell lines. Primary cultured normal trophoblast cells (NPT), human tumorigenic poorly differentiated trophoblast cell line (HT), and choriocarcinoma cell line (BeWo) were exposed to different concentrations of CIZAR® and cultured at different times. Cell viability was determined by CCK-8 assay. The effects on cell cycle progression, population distribution and apoptotic incidence were determined by flow cytometry. The appearance of apoptosis was confirmed by DNA laddering and DAPI staining. The quantitative analysis of telomerase was measured by TRAPeze® telomerase detection kit. The molecular mechanism of CIZAR®-induced apoptosis was examined with Western blot analysis and colorimetric caspase-3 activity assay. In in vitro condition, CIZAR® had a selective cytotoxic effect on choriocarcinoma cell line in dose- and time-dependent patterns. Flow cytometric analysis, DNA laddering, and DAPI staining indicated that BeWo cells only have been induced apoptosis by CIZAR®. Shortening of telomere was also observed only in BeWo cells. Results also displayed that CIZAR®-induced apoptosis involves the up-regulation of p21WAF1 and Bax protein and down-regulation of Bcl-2 which were accompanied by the activation of caspase-3. Taken together, our results suggest that CIZAR® is an apoptotic inducer in malignant trophoblast cells (BeWo).