Apoptotic effects of the novel histone deacetylase inhibitor BML-210 on HeLa cells

Abstract

Histone deacetylase inhibitors (HDACI) have been shown to inhibit cancer cell proliferation, induce cell cycle arrest, and stimulate apoptosis. To date, the key apoptotic proteins and pathways necessary for the anti-tumor activities of HDACI remain ill-defined, and the specific genes regulated by HDACI to mediate these effects have not been fully dissected. We have asked how novel HDACIs induce apoptosis, and how tumour cells can circumvent HDACI-mediated cell death. In the present study, we have investigated the antiproliferative effects of the novel HDACI, BML-210, and its combination with retinoic acid (RA) on human cervical cancer cells (HeLa). Cell cycle analysis indicated that HeLa cell treatment with BML-210 alone (10 μM) and in its 5 μM combination with 1 μM RA decreased the proportion of cells in G2/M phase, increased in G0/G1 and caused accumulation in subG1 indicating the cells undergoing apoptosis. These changes occurred concomitantly with the increased level of some proteins related to the malignant phenotype. We observed the activation of caspases 3, 8, 9 and an increase of the transcription factor NF-κB in the HeLa cell nucleus at 24 h of treatment with BML-210 or RA alone and in combination. Electrophoretic mobility shift assay (EMSA) experiments revealed an enhanced binding activity of NF-κB and the transcription factor p53 to the p21 promoter immediately after treatment with BML-210. In conclusion, these results suggest that BML-210 and its combination with RA are effective in inhibiting growth and inducing apoptosis in HeLa cells in vitro. The findings imply that BML-210 may prove particularly effective in cancer therapy. Keywords: apoptosis, HeLa cells, retinoic acid, BML-210, histone deacetylase inhibitor