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Small molecule epigenetic modulators for enhancing recombinant antibody production in CHO cell cultures

Small molecule epigenetic modulators that modify epigenetic states in cells are useful tools for regulating gene expression by inducing chromatin remodeling. To identify small molecule epigenetic modulators that enhance recombinant protein expression in Chinese hamster ovary (CHO) cells, we examined eight histone deacetylase inhibitors (iHDACs) and six DNA methyltransferase inhibitors as chemical additives in recombinant CHO (rCHO) cell cultures. Among these, a benzamide‐based iHDAC, CI994, was the most effective in increasing monoclonal antibody (mAb) production. Despite suppressing cell growth, the addition of CI994 to mAb‐expressing GSR cell cultures at 10 μM resulted in a 2.3‐fold increase in maximum mAb concentration due to a 3.0‐fold increase in specific mAb productivity (qmAb). CI994 increased mAb messenger RNA levels and histone H3 acetylation in GSR cells, and chromatin immunoprecipitation‐quantitative polymerase chain reaction analysis revealed that CI994 significantly increased the histone H3 acetylation level at the cytomegalovirus promoter driving mAb gene expression, indicating that chromatin remodeling in the promoter region results in enhanced mAb gene transcription and qmAb. Similar beneficial effects of CI994 on mAb production were observed in mAb‐expressing CS13‐1.00 cells. Collectively, our findings indicate that CI994 increases mAb production in rCHO cell cultures by chromatin remodeling resulting from acetylation of histones in the mAb gene promoter.