BACKGROUND: The potential involvement of type 2 diabetes mellitus (T2DM) as a risk factor for colon cancer (CC) has been previously reported. Epigenetic changes, such as deregulation of long non-coding RNA (lncRNA) and microRNA (miR), have been linked to the advancement of CC; however, the effects of high glucose levels on their deregulation and, in turn, colon cancer remain unexplored. METHODS: Fifty patients had a dual diagnosis of CC and T2DM, and 60 patients with CC without diabetes mellitus were included in the study. qRT-PCR was used to examine the expression of lncRNA ANRIL and miR-186-5p in tissue samples. ANRIL, miR-186-5p, and their downstream target genes HIF-1α, PFK, HK, Bcl-2, and Bax were also determined in CC cell lines under various glucose conditions. Glucose uptake, lactate production and cells proliferation were estimated in CC cell lines. RESULTS: A significant upregulation of ANRIL expression levels (p<0.001) and a significant downregulation of miR-186-5p expression (p<0.001) in diabetic colon cancer specimens compared to those in non-diabetic colon cancer group were observed. MiR-186-5p expression levels were inversely correlated with ANRIL expression levels, blood glucose levels and HbA1c%. Concerning in vitro model, a significant upregulation of ANRIL, downregulation of miR-186-5p, upregulation of HIF-1α, glycolytic enzymes and activation of antiapoptotic pathway was detected in higher glucose concentrations than lower one. There was a significant increase of glucose uptake, lactate accumulation and proliferation of the Caco2 and SW620 cell lines in a dose dependent manner of glucose concentrations. Moreover, a significant positive correlation between glucose uptake and ANRIL expression was shown. CONCLUSIONS: A high-glucose environment can increase the tumor-promoting effect of ANRIL. ANRIL can promote glucose metabolism and colon cancer proliferation by downregulating miR-186-5p with subsequent upregulation of glycolysis enzymes expression and inhibition of apoptosis.
Cell Proliferation , Colonic Neoplasms , Diabetes Mellitus, Type 2 , Glucose , MicroRNAs , RNA, Long Noncoding , Humans , RNA, Long Noncoding/genetics , Colonic Neoplasms/metabolism , Colonic Neoplasms/genetics , Colonic Neoplasms/pathology , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/genetics , MicroRNAs/genetics , Male , Female , Middle Aged , Prognosis , Glucose/metabolism , Gene Expression Regulation, Neoplastic , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Case-Control Studies , Apoptosis , Follow-Up Studies , Tumor Cells, Cultured , Survival Rate , Aged
