Effect of sodium butyrate on ABC transporters in lung cancer A549 and colorectal cancer HCT116 cells

Abstract

Histone deacetylase (HDAC) inhibitors and DNA alkylators are effective components of combination chemo‑ therapy. The aim of the present study was to investigate the possible mechanism of their synergism by detecting the effect of HDAC inhibitors on the expression levels of drug trans‑ porters that export DNA alkylators. It was demonstrated that the HDAC inhibitor sodium butyrate (NaB) induced the differ‑ ential expression of multidrug resistant ATP‑binding cassette (ABC) transporters in lung cancer and colorectal cancer cells. Specifically, NaB increased the mRNA expression levels of ABC subfamily B member 1 (ABCB1), ABCC10 and ABCC12, and protein expression levels of multidrug resistance‑1 (MDR1), multidrug resistance‑associated protein 7 (MRP7) and MRP9. Moreover, NaB decreased the expression levels of ABCC1, ABCC2 and ABCC3 mRNAs, as well as those of MRP1, MRP2 and MRP3 proteins. The molecular mechanism underlying this process was subsequently investigated. NaB decreased the expression of HDAC4, but not HDAC1, HDAC2 or HDAC3. In addition, NaB promoted histone H3 acetylation and methylation at lysine 9, as well as MDR1 acetylation, suggesting that acetylation and methylation may be involved in NaB‑mediated ABC transporter expression. Thus, the present results indicated that the synergism of the HDAC inhibitors with the DNA alkylating agents may due to the inhibitory effect of MRPs by HDAC inhibitors. The findings also suggested the possibility of antagonistic effects following the combined treatment of HDAC inhibitors with MDR1 ligands.