BackgroundEnvironmental factors-induced dysfunction of esophageal squamous epithelium, including genomic DNA impairment and apoptosis, play an important role in the pathogenesis of esophageal squamous cell cancer. DNA damage-induced 45α (GADD45α) has been found promoting DNA repair and removing methylation marker, Therefore, in this study we will investigate whether GADD45α expression is induced and its mechanism in esophageal squamous cell cancer.MethodsTwo human esophageal squamous cell lines (ESCC), ECA109 and KYSE510 were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS). Lipofectamine 2000 was used to transfect cells. mRNA level of GADD45α was measured by reverse transcription-quantitive PCR (RT-qPCR), protein level of GADD45α was detected by western blot and Immunohistochemistry. Global DNA methylation of tissue sample was measured using the Methylamp Global DNA Methylation Quantification Ultra kit (Epigentek Group) and promoter methylation was measured by bisulfite sequencing.ResultsGADD45a mRNA and protein levels were increased significantly in tumor tissue than that in adjacent normal tissue. Hypomethylation of global genomic DNA and GADD45α promoter were found in ESCC. The cell sensitivity to Cisplatin DDP was decreased significantly in Eca109 and Kyse510 cells, in which GADD45α expression was down-regulated by RNA interference (RNAi). In addition, silence of GADD45a expression in ESCC cells inhibited proliferation and promoted apoptosis.ConclusionOverexpression of GADD45α gene is due to DNA hypomethylation in ESCC. GADD45α may be a protective factor in DDP chemotherapy for esophageal squamous cell carcinoma.

Many studies have provided valuable information about genomic and transcriptomic changes that occur in colorectal cancer (CRC). However, protein abundance cannot be reliably predicted by DNA alteration or mRNA expression, which can be partially attributed to post-transcriptional and/or translational regulation of gene expression. In this study, we identified increased translational efficiency (TE) as a hallmark of CRC by evaluating the transcriptomic and proteomic features of CRC patients, along with comparative transcriptomic and ribosome-protected mRNA analysis in colon epithelial cells and colon cancer cells. COPS7B was among the key genes that consistently showed both significant TE increase and protein elevation without transcriptional alteration in CRC. IGF2BP3 enhanced the TE of COPS7B mRNA to promote CRC growth and metastasis. COPS7B was found to be a component of the ribo-interactome that interacted with ribosomes to facilitate ribosome biogenesis and mRNA translation initiation. Collectively, this study revealed the proteomic features of CRC and highlighted elevated mRNA translation as a hallmark of CRC. The identification of the IGF2BP3-COPS7B axis underlying the increased protein synthesis rate in CRC provided a promising therapeutic target to treat this aggressive disease.