BackgroundDownregulated expression levels of microRNA-320a (miR-320a) were found in primary breast cancers and colorectal cancer. Previous findings indicated that miRNA-320a may involve in the cancer development. In this study, we explored the roles of miR-320a by targeting c-Myc in the tumor growth of hepatocellular carcinoma (HCC).MethodsQuantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-320a in 50 HCC tissues and four HCC cells. Luciferase reporter assay was conducted to confirm the direct downstream target of miR-320a in HEK-293 cells. The effect of miR-320a on endogenous c-Myc expression was investigated by transfecting miR-320a mimics into HepG2 and QGY-7703 cell lines. The c-Myc and miR-320a expressions were analyzed by immunohistochemistry (IHC) and qRT-PCR in the same HCC tissues. Furthermore, the biological functional correlation of miR-320a with c-Myc was determined by studying the effect of miR-320a mimics or c-Myc small interfering RNA (siRNA) on HCC cell proliferation and invasion.ResultsThe expression of miR-320a was downregulated in 50 HCC tissues and 4 HCC cells. Luciferase assay revealed that c-Myc is a direct target of miR-320a. IHC and Western blot analysis showed that the c-Myc expression was inhibited by miR-320a in HCC tissues and cell lines. Upregulation of miR-320a suppressed the HCC cell proliferation and invasion capacity induced by inhibiting c-Myc, and the results were consistent with the effects of c-Myc siRNA on tumor suppression. These results revealed that miRNA-320a inhibits tumor proliferation and invasion by targeting c-Myc in HCC cells.ConclusionOur results showed that miR-320a functions as a tumor suppressor in HCC. By targeting c-Myc directly, miR-320a inhibits the HCC cell growth. Our studies provide evidence of miR-320a as a potentially target for HCC treatment.

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It is well known that induction of hepatocyte senescence could inhibit the development of hepatocellular carcinoma (HCC). Until now, it is still unclear how the degree of liver injury dictates hepatocyte senescence and carcinogenesis. In this study, we investigated whether the severity of injury determines cell fate decisions between hepatocyte senescence and carcinogenesis. After testing of different degrees of liver injury, we found that hepatocyte senescence is strongly induced in the setting of severe acute liver injury. Longer-term, moderate liver injury, on the contrary did not result into hepatocyte senescence, but led to a significant incidence of HCC instead. In addition, carcinogenesis was significantly reduced by the induction of severe acute injury after chronic moderate liver injury. Meanwhile, immune surveillance, especially the activations of macrophages, was activated after re-induction of senescence by severe acute liver injury. We conclude that severe acute liver injury leads to hepatocyte senescence along with activating immune surveillance and a low incidence of HCC, whereas chronic moderate injury allows hepatocytes to proliferate rather than to enter into senescence, and correlates with a high incidence of HCC. This study improves our understanding in hepatocyte cell fate decisions and suggests a potential clinical strategy to induce senescence to treat HCC.

MicroRNAs (miRNAs) are a class of small non-coding RNAs and closely related to the pathogenesis of cancers. Increasing evidence indicates that miR-30a plays a profound role during the development of cancers. However, the functions of miR-30a in non-small-cell lung cancer (NSCLC) are still ambiguous. Here we found that miR-30a was decreased in lung adenocarcinoma A549 cells and in tissue samples from 14 patients by qRT-PCR, and also found that overexpression of miR-30a in A549 cells inhibited migration and invasion but not cell proliferation and cell cycle progression by wound-healing assay, matrigel invasion assay, MTS-based cell proliferation assay, and flow cytometry-based cell cycle analysis, respectively. We further explored the potential mechanism of miR-30a-mediated gene regulation in lung adenocarcinoma cell lines. EYA2 is a predicted target of miR-30a, and it has been found that EYA2 expression is inhibited by miR-30a in breast cancer cells. We demonstrated that EYA2 is a direct target of miR-30a by using the dual-luciferase reporter assay in A549 cells and showed that EYA2 protein levels are inversely correlated with miR-30a expression in A549 and BEAS-2B cells. In addition, we also confirmed the rescue effects of EYA2 overexpression in A549 cells by cotransfection with EYA2 expression vector and miR-30a mimics. Taken together, our results demonstrate that overexpression of miR-30a in lung adenocarcinoma A549 cells can inhibit cell migration and invasion, which is partially attributed to the decrease of EYA2 expression. Our findings suggest that miR-30a may be used as a new potential target for the treatment of lung adenocarcinoma in the future.

Background/Aims: GCNT3 is a member of N-acetylglucosaminyltransferase family involved with mucin biosynthesis. GCNT3 aberrant expression is known to promote the progression of several human cancers. However, its role in tumorigenesis and the progression of non-small cell lung cancer (NSCLC) has not been well-characterized. Our study investigated the functional mechanisms of GCNT3 regulated by microRNAs (miRNAs) in NSCLC. Methods: The differential expression of mRNAs in NSCLC tissues and matched adjacent non-cancerous lung tissues from patients in Xuanwei, Yunnan province, China, was screened via mRNA microarray. The expression of GCNT3 and its correlation with NSCLC progression was measured in 92 paired tumor tissues and adjacent normal tissues. The functions of GCNT3 in NSCLC cells and its underlying mechanisms were measured using siRNA and GCNT3-expression vectors. The miRNA immunoprecipitation (miRIP) method was used to identify the miRNAs targeting GCNT3. The protein were measured using western blot assay, and the mRNAs were measured by quantitative real-time PCR (qRT-PCR) assay. Cell proliferation was measured using Cell Counting Kit-8 (CCK-8) and a colony forming assays; cell migration and invasion assays were performed using 24-well Transwell chambers with 8-μm pores filter, and analyses of the cell cycle and apoptosis were performed via flow cytometric analysis. The dual luciferase reporter assay was performed to confirm whether GCNT3 gene was a direct target of miR-302b-3p. Results: GCNT3 was found to be highly expressed in both NSCLC tissues and cell lines, and higher expression correlated significantly with advanced tumor-node-metastasis (TNM) stage, positive lymph node metastasis, and poor overall survival. Knockdown of GCNT3 inhibited the proliferation, migration and invasion ability of NSCLC cells, while overexpression facilitated these activities. Further mechanistic experiments using miRIP and dual luciferase reporter assays revealed that GCNT3 was a direct target of miR-302b-3p. Low expression of miR-302b-3p was found in NSCLC cells and negatively correlated with GCNT3 levels, while miR-302b-3p overexpression inhibited the proliferation, migration and invasion of NSCLC cells. Co-transfection with miR-302b-3p and the expression vector of GCNT3 abrogated the effects of mir-302b-3p, confirming that miR-302b-3p inhibited NSCLC progression by targeting GCNT3. Western blotting revealed that E-cadherin, N-cadherin, vimentin, p-Erk and cyclin D1 were downstream molecules of miR-302b-3p/GCNT3 pathway. Conclusion: miR-302b-3p/GCNT3 axis regulated cell proliferation, migration, and invasion by activating the Erk signaling pathway and epithelial-mesenchymal transition (EMT), which was identified as a potential therapeutic target for NSCLC.