Histone-acetyl epigenome regulates TGF-β pathway-associated chemoresistance in colorectal cancer

TGF-β signaling pathway has been demonstrated to be closely related to chemoresistance, which is the major cause of recurrence and poor outcome in colorectal cancer (CRC), however, the comprehensive epigenetic landscape that functionally implicates in the regulation of TGF-β pathway-associated chemoresistance has not yet well established in CRC. In our study, chromatin immunoprecipitation sequencing (ChIP-seq) and Western blot were employed to investigate epigenetic modifications for histones in response to TGF-β1 intervene. We found that the activation of the TGF-β pathway was characterized by genome-wide high levels of H3K9ac and H3K18ac. Mechanistically, the activation of the TGF-β signaling pathway leads to the downregulation of the deacetylase HDAC4, resulting in the upregulation of H3K9ac and H3K18ac. Consequently, this cascade induces oxaliplatin chemoresistance in CRC by triggering the anti-apoptotic PI3K/AKT signaling pathway. Our in vivo experiment results confirmed that overexpression of HDAC4 significantly enhances the sensitivity of CRC to oxaliplatin chemotherapy. Moreover, the expression level of HDAC4 was positively correlated with patients' prognosis in CRC. Our data suggest that histone-acetyl modification demonstrates a crucial role in modulating TGF-β pathway-associated chemoresistance in CRC, and HDAC4 would be a biomarker for prognostic prediction and potential therapeutic target for treatment in CRC.