406940

MIR148A

microRNA 148a;MIR148A;microRNA 148a

hsa-mir-148a|microRNA 148

7p15.2

ncRNA

PURPOSE: MicroRNAs (miRNA) have been documented playing a critical role in cancer development and progression. In this study, we investigate the role of miR-148a in gastric cancer metastasis. EXPERIMENTAL DESIGN: We examined miR-148a levels in 90 gastric cancer samples by qRT-PCR and analyzed the clinicopathologic significance of miR-148a expression. The gastric cancer cells stably expressing miRNA-148a were analyzed for migration and invasion assays in vitro and metastasis assays in vivo; the target genes of miR-148a were further explored. RESULTS: We found that miR-148a expression was suppressed by more than 4-fold in gastric cancer compared with their corresponding nontumorous tissues, and the downregulated miR-148a was significantly associated with tumor-node-metastasis (TNM) stage and lymph node-metastasis. Functional assays showed that overexpression of miR-148a suppressed gastric cancer cell migration and invasion in vitro and lung metastasis formation in vivo. In addition, overexpression of miR-148a in GC cells could reduce the mRNA and protein levels of ROCK1, whereas miR-148a silencing significantly increased ROCK1 expression. Luciferase assays confirmed that miR-148a could directly bind to the 2 sites of 3 untranslated region of ROCK1. Moreover, in gastric cancer tissues, we observed an inverse correlation between miR-148a and ROCK1 expression. Knockdown of ROCK1 significantly inhibited gastric cancer cell migration and invasion resembling that of miR-148a overexpression. We further found that ROCK1 was involved in miR-148a-induced suppression of gastric cancer cell migration and invasion. CONCLUSIONS: miR-148a functions as a tumor metastasis suppressor in gastric cancer, and downregulation of miR-148a contributes to gastric cancer lymph node-metastasis and progression. miR-148a may have a therapeutic potential to suppress gastric cancer metastasis.

metastasis is responsible for the rapid recurrence and poor survival of malignancies. Epithelial-mesenchymal transition (EMT) has a critical role in metastasis. Increasing evidence indicates that EMT can be regulated by microRNAs (miRNAs). miR-148a is a liver-abundant miRNA. However, the role of miR-148a in the development of liver cancer remains largely unknown. In this study, we found that, compared with normal livers, miR-148a was significantly decreased in hepatocellular carcinoma (HCC) tissues, especially in those with the portal vein tumor thrombus. An in vitro transwell assay and an in vivo orthotopic liver xenograft model showed that the restoration of miR-148a expression significantly repressed the migration and pulmonary metastasis of hepatoma cells. Linear regression analysis revealed a positive correlation between the expression of miR-148a and the mRNA level of E-cadherin gene in human HCC tissues. Both gain- and loss-of-function studies disclosed that miR-148a promoted the expression of epithelial marker (E-cadherin) and reduced the levels of mesenchymal markers (N-cadherin, fibronectin or vimentin) in hepatoma cells. These data suggest that miR-148a may suppress EMT and cancer metastasis. Further mechanistic investigations showed that miR-148a directly inhibited Met expression by binding to its 3'-UTR. Moreover, the reintroduction of miR-148a attenuated the downstream signaling of Met, like activated phosphorylation of AKT-Ser473 and inhibitory phosphorylation of GSK-3beta-Ser9, and consequently reduced the nuclear accumulation of Snail, a transcription factor that promotes EMT. Taken together, miR-148a may negatively regulate Met/Snail signaling and therefore inhibit the EMT and metastasis of hepatoma cells. These findings highlight the significance of miR-148a downregulation in tumor progression and implicate miR-148a as an attractive candidate for cancer therapy.

MicroRNAs (miRNAs) have been shown to be dysregulated in virus-related cancers; however, miRNA regulation of virus-related cancer development and progression remains poorly understood. Here, we report that miR-148a is repressed by hepatitis B virus (HBV) X protein (HBx) to promote cancer growth and metastasis in a mouse model of hepatocellular carcinoma (HCC). Hematopoietic pre-B cell leukemia transcription factor-interacting protein (HPIP) is an important regulator of cancer cell growth. We used miRNA target prediction programs to identify miR-148a as a regulator of HPIP. expression of miR-148a in hepatoma cells reduced HPIP expression, leading to repression of AKT and ERK and subsequent inhibition of mTOR through the AKT/ERK/FOXO4/ATF5 pathway. HBx has been shown to play a critical role in the molecular pathogenesis of HBV-related HCC. We found that HBx suppressed p53-mediated activation of miR-148a. Moreover, expression of miR-148a was downregulated in patients with HBV-related liver cancer and negatively correlated with HPIP, which was upregulated in patients with liver cancer. In cultured cells and a mouse xenograft model, miR-148a reduced the growth, epithelial-to-mesenchymal transition, invasion, and metastasis of HBx-expressing hepatocarcinoma cells through inhibition of HPIP-mediated mTOR signaling. Thus, miR-148a activation or HPIP inhibition may be a useful strategy for cancer treatment.