Histone deacetylase inhibitor sodium butyrate suppresses DNA double strand break repair induced by etoposide more effectively in MCF-7 cells than in HEK293 cells.

Liping Li,Lijun Chen,Xiaodan Wu,Pengfei Wu,Jiangqin Liu,Li Ma,Youxiang Sun

doi:10.1186/s12858-014-0030-5

Abstract

BackgroundHistone deacetylase inhibitors (HDACi’s) are emerging as promising anticancer drugs alone or in combination with chemotherapy or radiotherapy agents. Previous research suggests that HDACi’s have a high degree of selectivity for killing cancer cells, but little is known regarding the impact of different cellular contexts on HDACi treatment. It is likely that the molecular mechanisms of HDACi’s involve processes that depend on the chromatin template, such as DNA damage and repair. We sought to establish the connection between the HDACi sodium butyrate and DNA double-strand break (DSB) damage in human breast cancer MCF-7 and non-cancerous human embryonic kidney293 (HEK293) cells.ResultsSodium butyrate inhibited the proliferation of both HEK293 and MCF-7 cells in a dose- and time- dependent manner, but the effects on MCF-7 cells were more obvious. This differential effect on cell growth was not explained by differences in cell cycle arrest, as sodium butyrate caused an arrest in G1/G2 phase and a decrease in S phase for both cell lines. At high doses of sodium butyrate or in combination with etoposide, MCF-7 cells formed fewer colonies than HEK293 cells. Furthermore, sodium butyrate enhanced the formation of etoposide-induced γ-H2AX foci to a greater extent in MCF-7 than in HEK293 cells. The two cells also displayed differential patterns in the nuclear expression of DNA DSB repair proteins, which could, in part, explain the cytotoxic effects of sodium butyrate.ConclusionsThese studies suggest that sodium butyrate treatment leads to a different degree of chromatin relaxation in HEK293 and cancerous MCF-7 cells, which results in differential sensitivity to the toxic effects of etoposide in controlling damaged DNA repair.

Highlights

Histone deacetylase inhibitors (HDACi’s) are emerging as promising anticancer drugs alone or in combination with chemotherapy or radiotherapy agents
Sodium butyrate suppresses the proliferation of human embryonic kidney293 (HEK293) and MCF-7 cells to different extents To verify the effects of sodium butyrate on the proliferation of HEK293 cells and cancerous MCF-7 cells, we performed Cell Counting Kit (CCK-8) assays
The effect appeared more dramatic for MCF7 cells: at 24 h, no difference could be seen at any concentration for HEK293, whereas for MCF-7 cells, the 2.0 mM (P

Summary

Introduction

Histone deacetylase inhibitors (HDACi’s) are emerging as promising anticancer drugs alone or in combination with chemotherapy or radiotherapy agents. It is likely that the molecular mechanisms of HDACi’s involve processes that depend on the chromatin template, such as DNA damage and repair. We sought to establish the connection between the HDACi sodium butyrate and DNA double-strand break (DSB) damage in human breast cancer MCF-7 and non-cancerous human embryonic kidney293 (HEK293) cells. Histone deacetylase inhibitors (HDACi’s) globally increase histone acetylation, Double strand breaks (DSBs) in DNA occur naturally in the genome during replication and are increased by exogenous DNA damaging agents. Many anti-cancer therapeutics, including radiotherapy and chemotherapy agents, kill tumor cells by inducing DSBs. DSB repair is. DSBs can be repaired through several pathways including homologous recombination, non-homologous end-joining and single strand annealing [6]. Understanding the relationship between DSB repair and HDACi anticancer effects is important for elucidating mechanistic details of DSB repair within chromatin that have the potential to be exploited in the clinic

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