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.
Liver regeneration is a complicated process, and understanding the regulatory mechanism will be helpful in the treatment of diseases associated with liver. In this study, the one-third liver resection model was established in Chiloscyllium plagiosum, and the whole transcriptome of the C. plagiosum was generated using the Illumina-Solexa sequencing platform. Differentially expressed genes were analyzed using bioinformatics methods and verified using quantitative real-time PCR (qRT-PCR). Using miRanda and TargetScan, we screened the microRNA library for miRNAs that target the glutathione S-transferase P1(GSTP1) gene. Dual-luciferase reporter assays were used to confirm binding between the miRNA and GSTP1. Finally, we used western blotting analysis to determine expression of the GSTP1 protein. As a result, 65,356 unigenes were obtained in normal and damaged liver tissues, with mean length of 955 bp. A total of 359 differentially expressed genes were acquired; 217 of which were upregulated, and 142 were downregulated, including the GSTP1 gene, following liver resection. The presence of the GSTP1 protein in C. plagiosum was shown for the first time. Luciferase reporter assay revealed that GSTP1 messenger RNA was targeted by ipu-miR-143. The discovery and differential expression analysis of GSTP1 in C. plagiosum will be a valuable resource to explain the molecular mechanism of GSTP1 regulation of liver repair.
Background: Aberrant suppression of cytochrome P450 3A5 (CYP3A5) is frequently observed in human esophageal squamous cell carcinoma (ESCC); however, its role and the epigenetic mechanism mediating transcriptional repression of CYP3A5 in ESCC remain poorly understood.Results: Herein, we examined the expression and prognostic role of CYP3A5 in tumor tissues obtained from patients with ESCC. CYP3A5 silencing correlated with poor survival in ESCC. Using the histone deacetylase (HDAC) inhibitor trichostatin A (TSA), RNA interference, reporter gene assays, and chromatin immunoprecipitation, HDAC4 was found to be the key enzyme responsible for the absence of H3K18/K27Ac, mediated via P300/CBP at the CYP3A5 promoter. Finally, using CYP3A5 knockdown, re-expression, and xenograft experiments, we demonstrated that CYP3A5 downregulation, resulting in ZEB2 activation, promoted ESCC invasion and migration. Conclusions: our findings indicate that CYP3A5 activation reverses ZEB2-induced epithelial-mesenchymal transition (EMT) and inhibits migration and invasion of ESCC cells.
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