No abstract

Here, we show that expression of ZNF281/ZBP-99 is controlled by SNAIL and miR-34a/b/c in a coherent feedforward loop: the epithelial-mesenchymal transition (EMT) inducing factor SNAIL directly induces ZNF281 transcription and represses miR-34a/b/c, thereby alleviating ZNF281 mRNA from direct down-regulation by miR-34. Furthermore, p53 activation resulted in a miR-34a-dependent repression of ZNF281. Ectopic ZNF281 expression in colorectal cancer (CRC) cells induced EMT by directly activating SNAIL, and was associated with increased migration/invasion and enhanced b-catenin activity. Furthermore, ZNF281 induced the stemness markers LGR5 and CD133, and increased sphere formation. Conversely, experimental down-regulation of ZNF281 resulted in mesenchymal-epithelial transition (MET) and inhibition of migration/invasion, sphere formation and lung metastases in mice. Ectopic c-MYC induced ZNF281 protein expression in a SNAIL-dependent manner. Experimental inactivation of ZNF281 prevented EMT induced by c-MYC or SNAIL. In primary CRC samples, expression of ZNF281 increased during tumour progression and correlated with recurrence. Taken together, these results identify ZNF281 as a component of EMT-regulating networks, which contribute to metastasis formation in CRC.

Purpose: Here, we determined whether epigenetic inactivation of miR-34a and miR-34b/c genes may serve as a prognostic marker for distant metastases in colon cancer.Experimental Design: Using a case-control study design of 94 primary colon cancer samples with and without liver metastases, we determined CpG methylation frequencies of miR-34a and miR-34b/c promoters, expression of miR-34a, and its targets c-Met, Snail, and b-catenin and their prognostic value.Results: miR-34a methylation was detected in 45.1% (n ¼ 42 of 93) of the samples and strongly associated with metastases to the liver (P ¼ 0.003) and lymph nodes (P ¼ 0.006). miR-34b/c methylation was detected in 91.9% of the samples (n ¼ 79/86). A significant inverse correlation between miR-34a methylation and expression of mature miR-34a (P ¼ 0.018) was detected. Decreased miR-34a expression was associated with upregulation of c-Met, Snail, and b-catenin protein levels (P ¼ 0.031, 0.132, and 0.004), which were associated with distant metastases (P ¼ 0.001, 0.017, and 0.005). In a confounder-adjusted multivariate regression model miR-34a methylation, high c-Met and b-catenin levels provided the most significant prognostic information about metastases to the liver (P ¼ 0.014, 0.031, and 0.058) and matched pairs showed a higher prevalence of these risk factors in the samples with distant spread (P ¼ 0.029). Finally, we obtained statistical evidence indicating that the simultaneous detection of these three markers has the highest prognostic value.Conclusions: Silencing of miR-34a and upregulation of c-Met, Snail, and b-catenin expression is associated with liver metastases of colon cancer. Detection of miR-34a silencing in resected primary colon cancer may be of prognostic value, especially in combination with detection of c-Met and b-catenin expression.

Repression of c-Kit by p53 is mediated by miR-This is an open-access article distributed under the terms of the Creative Commons AttributioAugust 6n License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. ABSTRACT:The

The transcription factor AP4 mediates epithelial-mesenchymal transition (EMT) in colorectal cancer but its control in this setting is not fully understood. Here, we report the definition of a double-negative feedback loop involving AP4 and miR-15a/16-1 that regulates EMT and metastatic progression. In colorectal cancer cells, AP4 was downregulated by DNA damage in a p53-dependent manner. AP4 downregulation by p53 was mediated indirectly by the tumor-suppressive microRNAs miR-15a and miR-16-1, which targeted the 3 0 untranslated region (3 0 -UTR) of AP4 mRNA, induced mesenchymal-epithelial transition (MET), and inhibited colorectal cancer cell migration and invasion. The downregulation of AP4 was necessary for induction of MET and cell cycle arrest by miR-15a/16-1. In tumor xenoplants, ectopic miR-15a/16-1 suppressed formation of lung metastases. Furthermore, AP4 directly suppressed expression of miR-15a/16-1. In clinical specimens of colorectal cancer, miR-15a levels inversely correlated with AP4 protein levels shown previously to correlate with distant metastasis and poor survival. In summary, our results define a double-negative feedback loop involving miR-15a/16-1 and AP4 that stabilizes epithelial and mesenchymal states, respectively, which may determine metastatic prowess. Cancer Res; 74(2); 532-42. Ó2013 AACR.