Institute of Drug Metabolism and Pharmaceutical Analysis, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, 310058, Hangzhou, China.
Department of Pharmacy, Hangzhou Cancer Hospital, 310002, Hangzhou, China.
Cell Death Dis. 2021 May 24;12(6):532. doi: 10.1038/s41419-021-03814-5.
Human intestinal peptide transporter PEPT1 is commonly repressed in human colorectal cancer (CRC), yet its relationship with sensitivity to the common CRC treatment ubenimex has not previously been elucidated. In this study, we confirmed PEPT1 suppression in CRC using real-time quantitative polymerase chain reaction and western blotting and then investigated the underlying epigenetic pathways involved using bisulfite sequencing, chromatin immunoprecipitation, siRNA knockdown, and reporter gene assays. We found that PEPT1 transcriptional repression was due to both DNMT1-mediated DNA methylation of the proximal promoter region and HDAC1-mediated histone deacetylation, which blocked P300-mediated H3K18/27Ac at the PEPT1 distal promoter. Finally, the effects of the epigenetic activation of PEPT1 on the CRC response to ubenimex were evaluated using sequential combination therapy of decitabine and ubenimex both in vitro and in xenografts. In conclusion, epigenetic silencing of PEPT1 due to increased DNMT1 and HDAC1 expression plays a vital role in the poor response of CRC to ubenimex.
人类肠道肽转运蛋白 PEPT1 在人结直肠癌（CRC）中通常受到抑制，但它与对常见 CRC 治疗药物乌苯美司敏感性的关系以前尚未阐明。在这项研究中，我们使用实时定量聚合酶链反应和 Western blot 证实了 CRC 中 PEPT1 的抑制作用，然后使用亚硫酸氢盐测序、染色质免疫沉淀、siRNA 敲低和报告基因检测来研究涉及的潜在表观遗传途径。我们发现，PEPT1 的转录抑制是由于近端启动子区域的 DNMT1 介导的 DNA 甲基化和 HDAC1 介导的组蛋白去乙酰化，这阻止了 P300 在 PEPT1 远端启动子处介导的 H3K18/27Ac。最后，我们使用去甲基化药物地西他滨和乌苯美司序贯联合治疗在体外和异种移植模型中评估了 PEPT1 的表观遗传激活对 CRC 对乌苯美司反应的影响。总之，由于 DNMT1 和 HDAC1 表达增加导致的 PEPT1 表观遗传沉默在 CRC 对乌苯美司反应不良中起着至关重要的作用。
