A G > C polymorphism (rs2910164) is located in the stem region opposite to the mature miR-146a sequence, which results in a change from G:U pair to C:U mismatch in the stem structure of miR-146a precursor. Here, we elucidated the biological significance of this polymorphism, based on cancer association study and cell model system. The cancer association study included 479 hepatocellular carcinoma (HCC) and 504 control subjects. We found that the genotype distribution of this polymorphism in HCC cases was significantly different from that in control subjects (P = 0.026). The association between the genotype and the risk of HCC was further analyzed using multivariate unconditional logistic regression, with adjustment for sex, age and hepatitis B virus status. The results revealed that male individuals with GG genotype were 2-fold more susceptible to HCC (odds ratio = 2.016, 95% confidence interval = 1.056-3.848, P = 0.034) compared with those with CC genotype. We next examined the influence of this polymorphism on the production of mature miR-146a and found that G-allelic miR-146a precursor displayed increased production of mature miR-146a compared with C-allelic one. Further investigations disclosed that miR-146a could obviously promote cell proliferation and colony formation in NIH/3T3, an immortalized but non-transformed cell line. These data suggest that the G > C polymorphism in miR-146a precursor may result in important phenotypic traits that have biomedical implications. Our findings warrant further investigations on the relation between microRNA polymorphism and human diseases.

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant tumors worldwide, and it is always the consequence of chronic hepatitis and liver cirrhosis. The nucleotide-binding domain, leucine-rich family (NLR), pyrin-containing 3 (NLRP3) inflammasome has been shown to orchestrate multiple innate and adaptive immune responses. However, little is known about its role in cancer. This study was performed to investigate the role of the NLRP3 inflammasome in the development and progression of HCC. The expression of NLRP3 inflammasome components was analyzed in HCC tissues and corresponding non-cancerous liver tissues at both the mRNA and protein levels. Our data demonstrate that the expression of all of the NLRP3 inflammasome components was either completely lost or significantly downregulated in human HCC, and that the deficiency correlated significantly with advanced stages and poor pathological differentiation. In addition, our data provide an overview of the expression of NLRP3 inflammasome components in the multi-stage development of HCC and indicate a surprising link between deregulation of the NLRP3 inflammasome molecular platform and HCC progression. In conclusion, this study presents a dynamic expression pattern of NLRP3 inflammasome components in multi-stage hepatocarcinogenesis and demonstrates that deregulated expression of the inflammasome is involved in HCC progression.

Sarcopenia is a condition characterized by progressive and generalized loss of skeletal muscle mass and function. In this study, we used a cross-sectional study with 1090 community-dwelling Chinese citizens aged 60 years and older to evaluate the association of type 2 diabetes mellitus (T2DM) with the risk of sarcopenia and pre-sarcopenia. Sarcopenia was defined using the Asian Working Group for Sarcopenia (AWGS) criteria that include both muscle mass and muscle function/physical activity. Pre-sarcopenia was defined as having low skeletal muscle index but with normal muscle/physical activity. The prevalence of sarcopenia and pre-sarcopenia was significantly higher in T2DM patients than in healthy controls (14.8% vs. 11.2%, p = 0.035 for sarcopenia, and 14.4% vs. 8.4%, p = 0.002 for pre-sarcopenia). In multivariate logistic regression analyses adjusting by age, gender, anti-diabetic medication, energy intake, protein intake, physical activity, and visceral fat area, we found that Chinese elderly with T2DM exhibited significantly increased risks of sarcopenia (OR = 1.37, 95% CI = 1.02–2.03) and pre-sarcopenia (OR = 1.73, 95% CI = 1.10–2.83) compared to non-diabetic individuals. This is the first study to evaluate the association of T2DM with the risks of sarcopenia and pre-sarcopenia in China. Among a group of community-dwelling Chinese elderly, T2DM was significantly associated with increased risks of sarcopenia and pre-sarcopenia.

1 miR-122 is a highly abundant, hepatocyte-specific microRNA. The biomedical significance and regulatory mechanisms of miR-122 remain obscure. We explored the role of miR-122 in tumorigenesis in the context of gene regulatory network. The miR-122 promoter and its transactivator were identified by way of luciferase reporter system, electrophoretic mobility shift, and chromatin immunoprecipitation assays. The miR-122 regulatory circuitry and its implication in hepatocarcinogenesis were identified using livers of different development stages, human hepatocellular carcinoma (HCC) tissues and cell lines, and aflatoxin B 1 (AFB 1 )-transformed cells. We characterized the 25.3 to 24.8 kb region upstream of miR-122 precursor as miR-122 promoter. Further investigation revealed that deletion of predicted CCAAT/enhancer-binding protein alpha (C/EBPa) binding sites C/EBPa knockdown significantly reduced miR-122 promoter activity and endogenous miR-122 expression; and C/ EBPa directly interacted with the miR-122 promoter in vitro and in vivo. These data suggest that C/EBPa is a transactivator for miR-122 transcription. We further demonstrated that miR-122 suppressed insulin-like growth factor 1 receptor (IGF-1R) translation and sustained glycogen synthase kinase-3 beta (GSK-3b) activity. The activated GSK-3b not only repressed cell proliferation, but also activated C/EBPa, which maintained miR-122 levels and thereby enforced IGF-1R suppression. Interestingly, down-regulation of miR-122 and C/EBPa, and up-regulation of IGF-1R were frequently observed in HCC tissues, and decreased miR-122 levels were associated with worse survival of HCC patients. Moreover, AFB 1 exposure resulted in decreased activity in GSK-3b, C/EBPa, and miR-122 and increased levels of IGF-1R, whereas restoration of miR-122 suppressed the tumorigenicity of HCC and AFB 1 -transformed cells. Conclusion: We have identified a novel GSK-3b-C/EBPa-miR-122-IGF-1R regulatory circuitry whose dysfunction may contribute to the development of HCC. Our findings provide new insight into miR-122's function and the mechanisms of hepatocarcinogenesis. (HEPATOLOGY 2010;52:1702-1712

Emerging evidence suggests that 17β-estradiol (E2) and estrogen receptor (ER) signaling are protective against hepatocellular carcinoma (HCC). In our previous study, we showed that E2 suppressed the carcinogenesis and progression of HCC by targeting NLRP3 inflammasome activation, whereas the molecular mechanism by which the NLRP3 inflammasome initiated cancer cell death was not elucidated. The present study aimed to investigate the effect of NLRP3 inflammasome activation on cell death pathways and autophagy of HCC cells. First, we observed an increasing mortality in E2-treated HCC cells, and then apoptotic and pyroptotic cell death were both detected. The mortality of HCC cells was largely reversed by the caspase 1 antagonist, YVAD-cmk, suggesting that E2-induced cell death was associated with caspase 1-dependent pyroptosis. Second, the key role of the NLRP3 inflammasome in autophagy of HCC cells was assessed by E2-induced activation of the NLRP3 inflammasome, and we demonstrated that autophagy was inhibited by the NLRP3 inflammasome via the E2/ERβ/AMPK/mTOR pathway. Last, the interaction of pyroptosis and autophagy was confirmed by flow cytometry methods. We observed that E2-induced pyroptosis was dramatically increased by 3-methyladenine (3-MA) treatment, which was abolished by YVAD-cmk treatment, suggesting that caspase 1-dependent pyroptosis was negatively regulated by autophagy. In conclusion, E2-induced activation of the NLRP3 inflammasome may serve as a suppressor in HCC progression, as it triggers pyroptotic cell death and inhibits protective autophagy.