Wnt Signaling In Colorectal Cancer Cells Research Articles

Upregulation of miR-22-3p contributes to plumbagin-mediated inhibition of Wnt signaling in human colorectal cancer cells

The emergence of resistance and side effects for currently available drugs warrant the need for an alternative treatment regime for colorectal cancer (CRC). Several natural compounds, including plumbagin, have exhibited promising anti-cancer effects in different cancer models, although the molecular mechanisms underlying their effects remain at large. We previously reported plumbagin-mediated inhibition of Wnt signaling in CRC cells and to unravel the actual mechanism, we hypothesized the involvement of miRNAs as they have emerged as critical regulators of gene expression. We performed miRNA-microarray to check if plumbagin-mediated effects are through alteration of miRNA expression and found 32 DE-miRNAs (11 upregulated and 21 downregulated), and KEGG enrichment analysis indicated that their target mRNAs are associated with several pathways relevant to CRC and Wnt signaling. miRNA-mRNA network analysis by miRNET revealed a highly upregulated miRNA upon plumbagin treatment, miR-22-3p, having multiple Wnt-associated mRNAs interacting partners. 3′UTR luciferase assays revealed that miR-22-3p directly targeted the 3′UTR of BCL9L (a coactivator of CTNNB1). miR-22-3p inhibited Wnt signaling by downregulating the levels of BCL9L and that of CTNNB1 and several Wnt-associated proteins (TCF4, c-Myc, CCND1, Snail, Slug, and vimentin) in CRC cells. We also demonstrated that both miR-22-3p and plumbagin reduced colony formation and caused apoptotic cell death (detected by Annexin V/PI dual staining), possibly through increased ROS (detection by Dihydroethidium staining) and decreased MMP (detection by MitoTracker™ Orange staining) in CRC cells. These effects of plumbagin were partially rescued by antimiR-22-3p, suggesting the involvement of miR-22-3p in plumbagin-mediated effects. The present study revealed that alteration in miR-22-3p levels by plumbagin contributes to the induction of apoptosis and its inhibitory effects on Wnt signaling and colony formation, thus providing a mechanistic basis behind its anti-cancer potential.

Suppression of Capn4 by microRNA-1271 impedes the proliferation and invasion of colorectal cancer cells

Accumulating evidence has suggested that calpain small subunit 1 (Capn4) plays an important role in the development and progression of malignant tumors. However, little is known about the role of Capn4 in colorectal cancer (CRC). In this study, we aimed to investigate the potential role of Capn4 in CRC and the regulation of Capn4 by microRNAs (miRNAs). Here, we found that Capn4 expression was highly up-regulated in CRC cell lines. Knockdown of Capn4 by siRNA significantly inhibited the proliferation and invasion of CRC cell lines. Furthermore, knockdown of Capn4 suppressed Wnt signaling in CRC cells. Interestingly, Capn4 was found to be a target gene of miR-1271, a tumor suppressive miRNA. The results showed that miR-1271 negatively regulated Capn4 expression in CRC cells. An inverse correlation between miR-1271 and Capn4 was also shown in CRC clinical tissues. Moreover, the overexpression of miR-1271 suppressed the proliferation, invasion and Wnt signaling of CRC cells. Importantly, we found that the restoration of Capn4 expression significantly reversed the antitumor effects of miR-1271 in CRC cells. Overall, these results suggest that miR-1271 inhibits the proliferation and invasion of CRC cells by down-regulating Capn4. Our study suggests that Capn4 and miR-1271 may serve as potential therapeutic targets for the treatment of CRC.

Tuning WNT-β-catenin signaling via BCL9 proteins for targeting colorectal cancer cells

Tuning WNT-β-catenin signaling via BCL9 proteins for targeting colorectal cancer cells

WNT5AExhibits Tumor-Suppressive Activity through Antagonizing the Wnt/β-Catenin Signaling, and Is Frequently Methylated in Colorectal Cancer

Aberrant activation of the Wnt/beta-catenin signaling pathway is associated with multiple tumors including colorectal cancer (CRC). WNT5A is a member of the nontransforming Wnt protein family, whose role in tumorigenesis is still ambiguous. We investigated its epigenetic alteration in CRCs. We examined its expression and methylation in normal colon, CRC cell lines, and tumors. We also evaluated its tumor-suppressive function and its modulation to Wnt signaling in CRC cells. WNT5A is silenced in most CRC cell lines due to promoter methylation, but is expressed in most normal tissues including the colon, and is unmethylated in normal colon epithelial cells. WNT5A expression could be reactivated by pharmacologic or genetic demethylation, indicating that methylation directly mediates its silencing. WNT5A methylation was frequently detected in CRC tumors (14 of 29, 48%), but only occasionally in paired normal colon tissues (2 of 15, 13%; P = 0.025). Ectopic expression of WNT5A, but not its nonfunctional short-isoform with the WNT domain deleted, in silenced CRC cells resulted in substantial inhibition of tumor cell clonogenicity, which is associated with down-regulated intracellular beta-catenin protein level and concomitant decrease in beta-catenin activity. WNT5A is frequently inactivated in CRC by tumor-specific methylation, and thus, is a potential biomarker. WNT5A could act as a tumor suppressor for CRC by antagonizing the Wnt/beta-catenin signaling.