Refining the predictors of outcome in patients with resectable esophageal cancer

Negative regulation of CDK6 expression by microRNA-126-5p and its influence on the proliferation and invasion of esophageal cancer cells

The present study aimed to investigate the expression of cyclin-dependent kinase 6 (CDK6) and microRNA-126-5p (miR-126-5p) in esophageal cancer tissues and cells, and their effect on esophageal cancer cell proliferation and invasion, and to explore the potential molecular mechanisms. The relative expression levels of CDK6 and miR-126-5p in esophageal cancer tissue, paracancerous tissue, and HEEC and EC109 cells were determined and compared using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A miR-126-5p overexpression vector was constructed and a stable EC109 cell line expressing miR-126-5p was established. The EC109 cell line was transfected with a CDK6 small interfering RNA sequence. The rate of cell proliferation was determined using the WST-8 method, and cell invasion was determined using a Transwell assay. In addition, the relative expression levels of genes were determined using RT-qPCR; the relative expression levels of proteins were determined by western blot analysis; the binding sites of CDK6 and miR-126-5p were analyzed using TargetScan software; and the interaction of CDK6 and miR-126-5p was verified using dual-fluorescence reporter gene expression. Esophageal tissues and EC109 cells expressed higher levels of CDK6 but significantly lower levels of miR-126-5p compared with adjacent tissues and HEEC cells, and their correlation coefficient between esophageal tissues and matched adjacent tissues was -7.526. The overexpression of miR-126-5p and CDK6 knockdown in the EC109 cell line inhibited cell proliferation and invasion compared with the control and NC (negative control) groups. miR-126-5p overexpression reduced the relative expression level of CDK6, and CDK6 knockdown by siRNA increased the expression of miR-126-5p. miR-126-5p regulated CDK6 expression by binding to the 3'-untranslated region of its mRNA. Overexpression miR-126-5p inhibited the proliferation and migration of esophageal cancer cells by targeting CDK6 and negatively regulating its expression. These findings contribute to the understanding of the underlying molecular mechanism of esophageal cancer.