Novel targets of miR-30, a microRNA required for biliary development

Hepatobiliary Differentiation: Principles from Embryonic Liver Development

Hepatocytes and biliary epithelial cells (BECs), the two endodermal cell types of the liver, originate from progenitor cells called hepatoblasts. Based principally on in vitro data, hepatoblasts are thought to be bipotent stem cells with the potential to produce both hepatocytes and BECs. However, robust in vivo evidence for this model has only recently emerged. We examine the molecular mechanisms that stimulate hepatoblast differentiation into hepatocytes or BECs. In the absence of extrinsic cues, the default fate of hepatoblasts is hepatocyte differentiation. Inductive cues from the hepatic portal vein, however, initiate transcription factor expression in hepatoblasts, driving biliary specification. Defining the mechanisms of hepatobiliary differentiation provides important insights into congenital disorders, such as Alagille syndrome, and may help to better characterize the poorly understood hepatic lineage relationships observed during regeneration from liver injury.

Serum MicroRNA Signatures in Recovery From Acute and Chronic Liver Injury and Selection for Liver Transplantation

We previously demonstrated a distinct hepatic microRNA (miRNA) signature (down-regulation of miRNA-23a, -150, - 200b, -503, and -663 and up-regulation of miRNA-20a) is associated with successful regeneration in auxiliary liver transplantation (ALT). This study aimed to evaluate whether the serum expression of this regeneration-linked miRNA signature is associated with clinical outcomes in acute and chronic liver disease. These were represented by patients with acetaminophen-induced acute liver failure (ALF; n = 18) and patients with hepatitis C virus (HCV) undergoing treatment with direct-acting antivirals (n = 56), respectively. Patients were grouped depending on their clinical outcome. Global serum miRNA expression was analyzed using polymerase chain reaction (PCR) arrays and selected miRNA expression using targeted PCR. We demonstrate that specific regeneration-linked miRNAs discriminate outcomes in both clinical scenarios. We further show that miRNA-20a, -23a, -150, -200b, -503, and -663 undergo concordant changes in expression in 3 distinct clinical settings: liver regeneration accompanying successful ALT, clinical recovery after ALF, and clinical recompensation after cure of HCV. This miRNA signature represents a potentially novel biomarker to predict outcome and optimize patient selection for liver transplantation in both acute and chronic liver disease.

miR-30e controls DNA damage-induced stress responses by modulating expression of the CDK inhibitor p21WAF1/CIP1 and caspase-3

MicroRNAs (miRNAs), a class of small non-coding RNAs that usually cause gene silencing by translational repression or degradation of mRNAs, are implicated in DNA damage-induced stress responses. To identify senescence-associated miRNAs, we performed microarray analyses using wild-type and p53-deficient HCT116 colon carcinoma cells that following gamma-irradiation (γIR) are driven into senescence and apoptosis, respectively. Several miRNAs including miR-30e were found upregulated in a p53-dependent manner specifically in senescent cells, but not in apoptotic cells. Overexpression of miR-30e in HCT116 cells not only inhibited γIR-, etoposide- or miR-34a-induced caspase-3-like DEVDase activities and cell death, but greatly accelerated and augmented their senescent phenotype. Consistently, procaspase-3 protein, but not mRNA decreased in the presence of miR-30e, whereas expression of the cyclin-dependent kinase inhibitor p21 increased both at the mRNA and protein level. Performing luciferase reporter gene assays, we identified the 3′-UTR of the caspase-3 mRNA as a direct miR-30e target. In contrast, although miR-30e was unable to bind to the p21 mRNA, it increased expression of a luciferase construct containing the p21 promoter, suggesting that the miR-30e-mediated upregulation of p21 occurs indirectly at the transcriptional level. Interestingly, despite suppressing procaspase-3 expression, miR-30e was unable to protect RKO colon carcinoma cells from DNA damage-induced death or to induce senescence, as miR-30e completely fails to upregulate p21 in these cells. These data suggest that miR-30e functions in a cell type-dependent manner as an important molecular switch for DNA damage-induced stress responses and may thus represent a target of therapeutic value.

MicroRNAs as biomarkers for liver injury: Current knowledge, challenges and future prospects

MicroRNAs (miRNAs) are short regulatory RNAs that are involved in various biological processes that regulate gene expression posttranscriptionally. Changes in miRNA expression can be detected in many physiological and pathological events, such as liver injury. Drug induced liver injury is a life threatening condition that frequently requires organ transplantation. Hepatotoxicity is also one of the major causes of drug failure in clinical trials and of drug withdrawal from the market. The profiling of miRNA expression shows great promise in monitoring liver injury, in the prediction of outcome in patients, and in the identification of liver-reactive compounds in toxicological assessment. Recent studies have demonstrated organ-specificity of some miRNAs (i.e., miR-122), which are released into biological fluids as a result of hepatocyte damage. This attests to the potential of miRNAs as noninvasive biomarkers to detect liver toxicity. This review presents information on miRNA signatures of hepatotoxicity and on the application of promising miRNA biomarkers in preclinical safety assessment. We further discuss the technical challenges associated with these emerging biomarkers for early diagnosis and detection of hepatotoxicity.

MicroRNA-30a suppresses non-small-cell lung cancer by targeting Myb-related protein B

Non-small-cell lung cancer (NSCLC) is one of the leading causes of cancer mortality worldwide. A growing body of evidence indicates that microRNA (miR) have important and diverse roles in the proliferation, apoptosis and metastasis of human cancer cells. In the present study, the molecular regulation mechanism of miR-30a and its potential target, Myb-related protein B (MYBL2) was investigated in NSCLC. Reverse transcription-quantitative polymerase chain reaction results showed that miR-30a was significantly downregulated in NSCLC tissues compared with adjacent normal tissues (P<0.05). MYBL2 has a putative miR-30a target site in its 3'untranslated region according to previous data, prediction databases and TargetScan software. In the present study, a negative correlation was demonstrated between miR-30a and MYBL2 expression in NSCLC. Direct interaction between miR-30a and MYBL2 was also confirmed via a dual-luciferase reporter assay. miR-30a overexpression inhibited the growth of A549 and H460 cells via MTT and bromodeoxyuridine incorporation assays, whereas miR-30a downregulation promoted cell proliferation. In addition, miR-30a overexpression not only increased cell apoptosis and induced cell cycle arrest in A549 and H460 cell lines, but also attenuated tumor growth, and mRNA and protein expression levels of MYBL2. The present findings suggest that miR-30a may suppress NSCLC by targeting MYBL2.

Breast Cancer: A Molecular and Redox Snapshot

SIGNIFICANCE

Breast cancer is a unique disease characterized by heterogeneous cell populations causing roadblocks in therapeutic medicine, owing to its complex etiology and primeval understanding of the biology behind its genesis, progression, and sustenance. Globocan statistics indicate over 1.7 million new breast cancer diagnoses in 2012, accounting for 25% of all cancer morbidities.

RECENT ADVANCES

Despite these dismal statistics, the introduction of molecular gene signature platforms, progressive therapeutic approaches in diagnosis, and management of breast cancer has led to more effective treatment strategies and control measures concurrent with an equally reassuring decline in the mortality rate.

CRITICAL ISSUES

However, an enormous body of research in this area is requisite as high mortality associated with metastatic and/or drug refractory tumors continues to present a therapeutic challenge. Despite advances in systemic chemotherapy, the median survival of patients harboring metastatic breast cancers continues to be below 2 years.

FUTURE DIRECTIONS

Hence, a massive effort to scrutinize and evaluate chemotherapeutics on the basis of the molecular classification of these cancers is undertaken with the objective to devise more attractive and feasible approaches to treat breast cancers and improve patients' quality of life. This review aims to summarize the current understanding of the biology of breast cancer as well as challenges faced in combating breast cancer, with special emphasis on the current battery of treatment strategies. We will also try and gain perspective from recent encounters on novel findings responsible for the progression and metastatic transformation of breast cancer cells in an endeavor to develop more targeted treatment options. Antioxid. Redox Signal. 25, 337-370.

A Pilot Study of MicroRNAs Expression Profile in Serum and HBsAg Particles: Predictors of Therapeutic Vaccine Efficacy in Chronic Hepatitis B Patients

Chronic hepatitis B (CHB) remains a global health problem. Therapeutic vaccination has been successfully employed to treat a subpopulation of CHB patients. Personalized treatment can not only improve therapeutic efficacy, but also decrease the cost of medical care. Since microRNAs (miRNAs) are highly conserved and are involved in many cellular processes, exploring their expression profiles in CHB patients in association with responsiveness to therapeutic vaccination may be an approach for personalized treatment. In this study, we examined the kinetic expression profiles of 13 miRNAs in sera and serum-derived hepatitis surface antigen (HBsAg) particles in 10 CHB patients including 5 responders and 5 nonresponders selected from a large cohort of 136 patients enroled in a phase III clinical trial using antigen-antibody immunogenic complex based therapeutic vaccine (YIC). Eight miRNAs were detected in both sera and HBsAg particles. Among them, the levels of serum miRNAs and serum-derived HBsAg-carried miRNAs (let-7f, miR-22, miR-30a, and miR-122) were significantly lower in the responders group compared to those in the nonresponders group at baseline and throughout the course of treatment. The lower baseline levels of serum miRNAs and HBsAg-carried miRNAs were also associated with hepatitis e antigen clearance at week 76 and hepatitis e antigen seroconversion during the study period. In summary, our study suggests that lower baseline levels of serum miRNAs and HBsAg-carried miRNAs (let-7f, miR-22, miR-30a, and miR-122) associated with YIC treatment response and the variation trend of these 4 miRNAs could have a prognostic value for responsiveness to YIC treatment.