Combined Effects of 4-HPR and DDP on the Proliferation and Apoptosis of HeLa Cells

BACKGROUND AIM: N-4-hydroxyphenyl retinode(4-HPR) is a synthetic amide analogue of ATRA. It was reported that 4-HPR could inhibit the growth of cervical cancer cells in vitro. Cis-platinum ( DDP) is a first choice chemical agent used in cervical cancer chemotherapy. The purpose of this study was to investigate the combination effects of 4-HPR and DDP on the proliferation, apoptosis of human cervical cancer HeLa cells, and to further provide experimental evidence for treating advanced stage cervical cancer with 4-HPR. MATERIAL AND METHODS: HeLa cells were cultured in vitro, MTT assay was used to assess the antiproliferative effect of 4-HPR with or without DDP on HeLa cells. Flow cytometry (FCM) was used to study the effects of 4-HPR with or without DDP on cell cycle and apoptosis of HeLa cells. Hoechst 33258 was used to examine the nuclear changes of the HeLa cells. RESULTS: 4-HPR produced concentration- and time-dependent antiproliferative effects on HeLa cells in the range of 2 to 40 μmol/L for 72 h and the effects were more significant with combined use of 4-HPR and DDP. 4-HPR also induced concentration-dependent apoptosis in HeLa cells and arrested cells in the G2/M-phase and S-phase of cell cycle. The apoptosis ratios were at 2.55%, 16.55% and 22.91%, when the cells were exposed to 4-HPR at 10, 20, 40 μmol/L respectively for 72 h. The percentages of cells at G2/M-phase and S-phase increased with higher concentration of,4-HPR. The synergistic effect between 4-HPR (at 10, 20, 40 μmol/L) and 1 μmol/L DDP was found in inducing HeLa cells apoptosis and G2/M-phase and S-phase arrest. CONCLUSION: Using 4-HPR alone could inhibit the growth of human cervical cancer cells, and DDP could enhance cellular sensitivity to 4-HPR. These results suggested that the synergistic effect between 4-HPR and DDP could be related to the combined induction of G2/M-phase and S-phase arrest in HeLa cells.