Expression of miR-34 is lost in colon cancer which can be re-expressed by a novel agent CDF

Abstract

BackgroundColorectal Cancer (CRC) is one of the leading causes of death worldwide. Numerous cellular events, including deregulated expression of microRNAs (miRNAs), specifically the family of miR-34 consisting of miR-34a, b and c, is known to regulate the processes of growth and metastasis.MethodsWe evaluated the expression of miR-34 in formalin-fixed paraffin-embedded (FFPE) human colon cancer tissue specimens compared to normal colonic mucosa. Moreover, we also assessed the expression of miR-34 in colon cancer cell lines treated with our newly developed synthetic analogue of curcumin referred as difluorinated curcumin (CDF) compared to well known inhibitor of methyl transferase.ResultsWe found that the expression of miR-34a and miR-34c was down-regulated in colon cancer specimens compared to normal colonic mucosa and the loss of expression was also consistent with data from colon cancer cell lines. This down-regulation was attributed to promoter hypermethylation, because we found that the treatment of colon cancer cells with 5-aza-2´-deoxycytidine, a methyltransferase inhibitor, markedly induced the levels of miR-34a and miR-34c expression. Likewise, CDF was very effective in the re-expression of miR-34a and miR-34c, which was consistent with inhibition of cell growth of both chemo-sensitive and chemo-resistant colon cancer cells. The re-expression of miR-34 led to a marked reduction in the expression of its target gene, Notch-1.ConclusionThe loss of expression of miR-34 in colon cancer is in part due to promoter hypermethylation of miR-34, which can be re-expressed with our novel agent CDF, suggesting that CDF could be a novel demethylating agent for restoring the expression of miR-34 family, and thus CDF could become a newer therapeutic agent for the treatment of colon cancer.

Targeting Epigenetically Deregulated miRNA by Nutraceuticals: Focusing on Cancer Prevention and Treatment

“…It was found that the level of miR-34a/miR-34c was downregulated in colon cancer tissues and cell lines [68]. The decreased expression of miR-34a/miR-34c was, in part, due to hypermethylation of miR-34 promoter.…”

“…The decreased expression of miR-34a/miR-34c was, in part, due to hypermethylation of miR-34 promoter. Importantly, the treatment of colon cancer cells with CDF or demethylating agent 5-aza-2-deoxycytidine significantly upregulated the expression of miR-34a/34c and decreased the level of Notch 1, a target of miR-34, resulting in the inhibition of colon cancer cell growth [68].…”

Crosstalk between the Notch signaling pathway and non‑coding RNAs in gastrointestinal cancers (Review)

“…It was revealed that miR-34a and miR-34c expression were downregulated in colon cancer tissues, and that the decreased level of miR-34 in colon cancer is partially due to the hyper-methylation of the miR-34 gene promoter (48). Notch1 has been identified as a direct target of miR-34b and 34c in HeLa cells (48,49). miR-34a may reduce the expression of Notch-1 in colon cancer cells (48).…”

“…Notch1 has been identified as a direct target of miR-34b and 34c in HeLa cells (48,49). miR-34a may reduce the expression of Notch-1 in colon cancer cells (48). Notably, research has also demonstrated that miR-34a may act as a bimodal switch to regulate Notch1, to determine the cell fate of early state dividing colon cancer stem cells (CCSCs) (9).…”

Impact of curcumin on the regulation of microRNAs in colorectal cancer

“…Moreover, miR-34 family induces apoptosis in human cancer cells through targeting several anti-apoptotic members of the Bcl-2 family, and signal transduction factors including Akt and the ancestral receptor Notch-1 [24]. In this context, CDF was shown to restore the expression of miR-34a and miR-34c in an in vitro model of colon carcinoma, leading to the downregulation of their target gene Notch-1 [25]. This effect was likely due to the demethylation of miR-34a promoter induced by CDF.…”