Transcriptional activation of microRNA-34a by NF-kappa B in human esophageal cancer cells

Abstract

BackgroundmiR-34a functions as an important tumor suppressor during the process of carcinogenesis. However, the mechanism of miR-34a dysregulation in human malignancies has not been well elucidated. Our study aimed to further investigate the regulation mechanism of miR-34a.ResultsWe found that overexpression of NF-kappa B p65 subunit could increase miR-34a levels in EC109, an esophageal squamous cancer cell line, while ectopic expression of DN IkappaB leaded to a significant reduction of miR-34a expression. Bioinformatics analysis suggested three putative KB sites in promoter region of miR-34a gene. Mutation two of these KB sites impaired p65 induced miR-34a transcriptional activity. Chromatin immunoprecipitation and electrophoretic mobility shift assays both showed that NF-kappaB could specifically bind to the third KB site located in miR-34a promoter. In addition, we found that overexpression of NF-kappaB p65 could not successfully induce miR-34a expression in esophageal cancer cell lines with mutant p53 or decreased p53. Reporter assay further showed that NF-kappaB-induced miR-34a transcriptional activity was reduced by p53 impairment. Nevertheless, CHIP analysis suggested binding of NF-kappaB to miR-34a promoter was not affected in cells with mutant p53.ConclusionsOur work indicates a novel mechanism of miR-34a regulation that NF-kappaB could elevate miR-34a expression levels through directly binding to its promoter. And wildtype p53 is responsible for NF-kappaB-mediated miR-34a transcriptional activity but not for NF-kappaB binding. These findings might be helpful in understanding miR-34a abnormality in human malignancies and open new perspectives for the roles of miR-34a and NF-kappaB in tumor progression.

NF‐κB inhibition reverses acidic bile‐induced miR‐21, miR‐155, miR‐192, miR‐34a, miR‐375 and miR‐451a deregulations in human hypopharyngeal cells

“…MiR‐34a is a known tumour suppressor and key regulator miRNA in HNSCC,17, 23 and our prior in vivo findings showed that acidic bile down‐regulated miR‐34a levels in treated laryngopharyngeal mucosa. Although previous studies reported NF‐κB binding sites on the promoter of miR‐34a,21, 56 and an increase in miR‐34a levels in oesophageal cells under NF‐κB activation,21 the exact mechanism of miR‐34a regulation by NF‐κB is not yet obvious. Alternatively, it has been shown that STAT3 can directly repress miR‐34a, while an active IL‐6R/STAT3/miR‐34a loop was found necessary for EMT, invasion and metastasis of colorectal cancer cell line 56.…”

“…Previous studies have demonstrated that deregulation of “oncomirs” miR‐21, miR‐155, miR‐192 and tumour suppressor miR‐375, miR‐451a and miR‐34a is associated with laryngopharyngeal cancer 12, 13, 14, 15, 16, 17. Moreover, an independent association has been demonstrated between NF‐κB activation and up‐regulation of oncogenic miR‐21 and/or down‐regulation of tumour suppressor miR‐34a and miR‐451a 21, 22, 23…”

Sirtuin 1: A Target for Kidney Diseases

“…On the contrary, there was also evidence indicating that NF-κB inhibited SIRT1 expression and signaling. Reportedly, NF-κB could increase the expression of microRNA-34a (miR-34a), which targeted the 3′UTR of SIRT1 and inhibited SIRT1 expression (138)(139)(140)(141). SIRT1 even became cleaved in inflammatory status (78,79).…”

Tonglian Decoction (通莲汤) arrests the cell cycle in S-phase by targeting the nuclear factor-kappa B signal pathway in esophageal carcinoma Eca109 cells

“…(20) The NF-κB transduction pathway is constitutively activated in human esophageal cell lines, suggesting that some of the proteins involved in the pathway play critical roles in carcinogenesis of the esophagus. (21,22) Our experiment showed that in Eca190 cells, TLD inhibited the expression of several proteins in the NF-κB signal pathway, including IKKβ, NF-κB, TNF-α and IL-1β, which is probably the pharmacological mechanism of the regulation of cell proliferation.…”