MicroRNA‐182 targets cAMP‐responsive element‐binding protein 1 and suppresses cell growth in human gastric adenocarcinoma

Abstract

MicroRNAs (miRNAs) constitute a class of noncoding RNAs that post‐transcriptionally regulate gene expression. Recent evidence indicates that many miRNAs function as oncogenes or tumor suppressors by negatively regulating their target genes. In our previous study, using miRNA microarray analysis, we found that miRNA‐182 (miR‐182) was significantly downregulated in human gastric adenocarcinoma tissue samples. Here, we confirmed the downregulation of miR‐182 in a larger sample of gastric tissue samples. Overexpression of miR‐182 suppressed the proliferation and colony formation of gastric cancer cells. An oncogene, encoding cAMP‐responsive element binding protein 1 (CREB1), serves as a direct target gene of miR‐182. A fluorescent reporter assay confirmed that miR‐182 binds specifically to the predicted site of the CREB1 mRNA 3′‐UTR. When miR‐182 was overexpressed in gastric cancer cell lines, both the mRNA and protein levels of CREB1 were depressed. Furthermore, CREB1 was present at a high level in human gastric adenocarcinoma tissues, and this was inversely correlated with miR‐182 expression. Ectopic expression of CREB1 overcame the suppressive phenotypes of gastric cancer cells caused by miR‐182. These results indicate that miR‐182 targets the CREB1 gene and suppresses gastric adenocarcinoma cell growth, suggesting that miR‐182 shows tumor‐suppressive activity in human gastric cancer.

MicroRNA-182-5p targets a network of genes involved in DNA repair

“…Another component of the SCF complex, BTRC, is also known to ubiquitylate ATF4, which plays a role in maintaining genomic integrity (Lassot et al 2001). The repression of these two classes of proteins by miR-182-5p could lead to a normal functioning DDR, which may explain the tumor-suppressive effects of this miRNA observed in lung cancer (Sun et al 2010;Zhang et al 2011), and human gastric adenocarcinoma (Kong et al 2012), in a manner analogous to miR-17-5p's dual functionality Hossain et al 2006;Volinia et al 2006;Zhang et al 2006). miR-182-5p modulates PARP inhibitor sensitivity by targeting multiple components of the DNA repair pathway miR-182-5p has recently been reported to target BRCA1 (Moskwa et al 2011), a critical component of the homologous recombination (HR) pathway, in breast cancer cell lines.…”

“…Relevant to this point are the conflicting reports regarding miR-182-5p's molecular role in tumorigenesis. Whereas there appears to be an oncogenic role for this miRNA in some cancers including melanoma (Segura et al 2009), endometrioid endometrial cancer (Myatt et al 2010), and glioma ; in others, such as lung adenocarcinoma (Sun et al 2010;Zhang et al 2011) and human gastric adenocarcinoma (Kong et al 2012), its role is more akin to that of a tumor suppressor. Such dual-function miRNAs have been previously reported: miR-26a (Sander et al 2008;Huse et al 2009;Kota et al 2009;Kim et al 2010), miR-205 (Iorio et al 2007, 2009Gandellini et al 2009;Wu et al 2009), and miR-17-5p (Hossain et al 2006;Mraz et al 2009;Yu et al 2010;Li et al 2011) are all characterized examples.…”

“…In contrast, a tumor-suppressive role for miR-182-5p has been established in lung cancer (Sun et al 2010;Zhang et al 2011), and gastric adenocarcinoma (Kong et al 2012), where overexpression of this miRNA leads to suppression of cell growth. Despite the widespread association of altered miR-182-5p expression across a range of human cancers, only a few targets have been identified so far; including FOXO3, MITF (Segura et al 2009), FOXO1 (Guttilla and White 2009), BRCA1 (Moskwa et al 2011), CTTN (Sun et al 2010), RGS17 (Sun et al 2010), and more recently CREB1 (Kong et al 2012) and MTSS1 . Recently, miR-182-5p, along with other miRNAs in its cluster, has been shown to affect apoptosis, senescence, proliferation, and migration/motility in medulloblastoma (Weeraratne et al 2012).…”

Functional characterization of miRNAs in tumour biology

“…Another component of the SCF complex, BTRC, is also known to ubiquitylate ATF4, which plays a role in maintaining genomic integrity (Lassot et al 2001). The repression of these two classes of proteins by miR-182-5p could lead to a normal functioning DDR, which may explain the tumor-suppressive effects of this miRNA observed in lung cancer Zhang et al 2011), and human gastric adenocarcinoma (Kong et al 2012), in a manner analogous to miR-17-5p's dual functionality Hossain et al 2006;Volinia et al 2006;Zhang et al 2006). miR-182-5p modulates PARP inhibitor sensitivity by targeting multiple components of the DNA repair pathway miR-182-5p has recently been reported to target BRCA1 (Moskwa et al 2011), a critical component of the homologous recombination (HR) pathway, in breast cancer cell lines.…”

“…In contrast, a tumor-suppressive role for miR-182-5p has been established in lung cancer Zhang et al 2011), and gastric adenocarcinoma (Kong et al 2012), where overexpression of this miRNA leads to suppression of cell growth. Despite the widespread association of altered miR-182-5p expression across a range of human cancers, only a few targets have been identified so far; including FOXO3, MITF (Segura et al 2009), FOXO1 (Guttilla and White 2009), BRCA1 (Moskwa et al 2011), CTTN , RGS17 , and more recently CREB1 (Kong et al 2012) and MTSS1 . Recently, miR-182-5p, along with other miRNAs in its cluster, has been shown to affect apoptosis, senescence, proliferation, and migration/motility in medulloblastoma (Weeraratne et al 2012).…”