The global morbidity and mortality of colorectal cancer (CRC) are ranked the third among gastrointestinal tumors in the world. MiR-451a is associated with several types of cancer, including CRC. However, the roles and mechanisms of miR-451a in CRC have not been elucidated. BAP31 is a predicted target gene of miR-451a in our suppression subtractive hybridization library. Its relationship with miR-451a and function in CRC are unclear. We hypothesized that miR-451a could induce apoptosis through suppressing BAP31 in CRC. Immunohistochemistry and real-time PCR were used to measure BAP31 expressions in CRC tissues and pericarcinous tissues from 57 CRC patients and CRC cell lines. Dual-luciferase reporter assay was used to detect the binding of miR-451a to BAP31. The expression of BAP31 protein in CRC tissues was significantly higher than that in pericarcinous tissues, which was correlated with distant metastasis and advanced clinical stages of CRC patients. The expression of BAP31 was higher in HCT116, HT29, SW620, and DLD cells than that in the normal colonic epithelial cell line NCM460. The expression of BAP31 was absolutely down-regulated when over-expressing miR-451a in HCT116 and SW620 cells compared with control cells. Mir-451a inhibited the expression of BAP31 by binding to its 5’-UTR. Over-expressing miR-451a or silencing BAP31 suppressed the proliferation and apoptosis of CRC cells by increasing the expressions of endoplasmic reticulum stress (ERS)-associated proteins, including GRP78/BIP, BAX, and PERK/elF2α/ATF4/CHOP, which resulted in increased ERS, cytoplasmic calcium ion flowing, and apoptosis of CRC cells. These changes resulting from over-expressing miR-451a were reversed by over-expressing BAP31 with mutated miR-451a-binding sites. Over-expressing miR-451a or silencing BAP31 inhibited tumor growth by inducing ERS. The present study demonstrated that miR-451a can inhibit proliferation and increase apoptosis through inducing ERS by binding to the 5’-UTR of BAP31 in CRC.

Abstract. Change in cellular glucose metabolism is considered to be a biochemical hallmark in cancer cells. The mitochondrion is the key organelle in which glucose metabolism occurs. However, whether DNA methylation at the displacement loop (D-loop) region of mitochondrial DNA (mtDNA) has an effect on the expression of the rate-limiting enzyme, and, therefore, on oxidative phosphorylation in colorectal cancer remains to be determined. Quantitative change in ND2 (a subunit of NADH) and the methylation status of the D-loop were observed during the initiation and progression of colorectal cancer. Furthermore, the possible correlations with clinicopathological stage were also investigated. Tumor and corresponding non-cancerous tissues were surgically resected from 44 colorectal cancer patients between 2008 and 2009. Cox IV expression was quantified in all of the specimens, and the ND2 expression was calculated. Quantitative changes in ND2 expression exhibited a significant increase. The average relative ratios of ND2 content were 1.67±0.44 in the tumor tissues and 0.89±0.44 in the corresponding non-cancerous tissues (p<0.01). In addition, the D-loop of most corresponding non-cancerous tissues was methylated and the percentage was 79.5%, while this percentage was much smaller in the tumor tissues (11.4%). Following correlation with clinicopathological data, changes in the ND2 expression in the colorectal cancer exhibited a significant association with clinicopathological stage. This increase was significant as early as in stage Ⅰ. Furthermore, the ratios of unmethylated D-loop cases were increased in both tumor and corresponding non-cancerous tissues, and the ND2 expression was also increased from stages Ⅰ to Ⅳ. Our results indicate that demethylation of the D-loop plays a key role in regulating ND2 expression during the initiation and/or progression of colorectal cancer.

This article was designed by using a network pharmacological approach to reveal the therapeutic targets and molecular mechanisms of oxyresveratrol (Oxyres) treating colorectal cancer (CRC). Furthermore, several bioinformatic findings would be validated. Pathogenetic targets of CRC and pharmacological targets of Oxyres were identified by web-available databases. All identifiable biotargets were collected for functional enrichment analyses to reveal the biological processes and signaling pathways of Oxyres treating CRC. In addition, human CRC, non-CRC samples, and cell line study were used to validate the predictive biotargets of Oxyres treating CRC. In network pharmacological analyses, top therapeutic targets of mitogenactivated protein kinase 1 (MAPK1), insulin growth factor 1 (IGF1), hematopoietic prostaglandin D synthase (HPGDS), GTPase HRas (HRAS), and cytochrome P450 2C9 (CYP2C9) in Oxyres treating CRC were identified, respectively. As shown in functional analysis, biological processes of Oxyres treating CRC were mainly involved in modulating cell communication, signal transduction, apoptosis, cell motility, cell proliferation, and lipid metabolism. Furthermore, top 10 signaling pathways of Oxyres treating CRC were identified, respectively. In human study, CRC samples resulted in increased neoplastic expressions of Ki-67, MAPK1, IGF1, characterized with clinical imaging inspection, pathological diagnosis, and altered blood lipids in these CRC cases. In cell culture study, Oxyres-dosed CRC cells exhibited reduced cell proliferation, promoted cellular apoptosis. Furthermore, significantly decreased proteins of intracellular Ki-67, MAPK1, and IGF1 were observed in Oxyres-dosed cells when compared to those in controls. Collectively, anti-CRC pharmacological activity of Oxyres may be mainly associated with induction of apoptosis and suppression of cell proliferation as revealed in bioinformatic findings. In addition, all core biotargets and molecular mechanisms of Oxyres treating CRC are