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BackgroundExtrahepatic Cholangiocarcinoma (EHCC) is one of the uncommon malignancies in the digestive system which is characterized by a poor prognosis. Aberrations of miRNAs have been shown involved in the progression of this disease. In this study, we evaluated the expression and effects of miR-34a on EHCC.MethodsmiR-34a expression levels were detected in EHCC tissues, adjacent non-tumor tissues, normal bile duct (NBD) specimens of patients and cholangiocarcinoma (CC) cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). Relationships between miR-34a with clinical characteristics of EHCC patients were further analyzed. Computational search, functional luciferase assay and western blot were further used to demonstrate the downstream target of miR-34a in CC cells. Immunohistochemistry was carried on to identify the downstream target gene of miR-34a in EHCC patients. Cell morphology, invasion and migration assays were further applied to confirm the anti-carcinogenic effects of miR-34a through the downstream target.ResultsmiR-34a expression was significantly decreased in human EHCC tissues and CC cell lines when compared with the adjacent non-tumor tissues and normal bile duct tissues. miR-34a was found correlated with the migration and invasion in EHCC patients. Smad4 was over-expressed in most of the EHCC patients and was further demonstrated as one of the downstream targets of miR-34a, which was involved in the progression of EHCC. Moreover, activation of miR-34a suppressed invasion and migration through TGF-beta/Smad4 signaling pathway by epithelial-mesenchymal transition (EMT) in vitro.ConclusionsTaken together, our results suggest that miR-34a inhibits invasion and migration by targeting Smad4 to suppress EMT through TGF- beta/Smad signaling pathway in human EHCC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1359-x) contains supplementary material, which is available to authorized users.

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Abstract. microRNAs (miRNAs) are a class of small non-coding RNAs that post-transcriptionally regulate gene expression. Increasing evidence has shown that the deregulation of miRNAs is linked to cancer. The overexpression of miR-224 has been reported in several human cancers. The aim of the present study was to investigate the function of miR-224 in the pathogenetic process of hepatocellular carcinoma (HCC), and the precise mechanism underlying its function. Both gain-of-function and loss-of function assays were conducted through transfection with miR-224 mimics and miR-224 inhibitors in the HepG2 liver carcinoma cell line. The data revealed that miR-224 exerts a significant role in promoting cell proliferation, migration and invasion. Western blot analysis showed that the phosphorylation levels of AKT positively correlated with endogenous levels of miR-224. In addition, results from a dual luciferase reporter assay showed that the expression of the serine/threonine-protein phosphatase 2A 65 kDa regulatory subunit A β isoform (PPP2R1B) is inhibited by miR-224; thus, it appears that PPP2R1B is a candidate target of miR-224 in HCC. These data suggest that miR-224 plays a significant role in HCC, possibly through the activation of the AKT signaling pathway by targeting PPP2R1B.

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Great progress has been achieved in the study of the role of TGF-β signaling in triggering epithelial-mesenchymal transition (EMT) in a variety of cancers; however, the regulation of TGF-β signaling during EMT in mammary tumor metastasis has not been completely defined. In the present study, we demonstrated that OVOL2, a zinc finger transcription factor, inhibits TGF-β signaling-induced EMT in mouse and human mammary tumor cells, as well as in mouse tumor models. Data from the Oncomine databases indicated a strong negative relationship between OVOL2 expression and breast cancer progression. Moreover, our experiments revealed that OVOL2 inhibits TGF-β signaling at multiple levels, including inhibiting Smad4 mRNA expression and inducing Smad7 mRNA expression, blocking the binding between Smad4 and target DNA, and interfering with complex formation between Smad4 and Smad2/3. These findings reveal a novel mechanism that controls the TGF-β signaling output level in vitro and in vivo. The modulation of these molecular processes may represent a strategy for inhibiting breast cancer invasion by restoring OVOL2 expression.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been shown to attenuate ischemia reperfusion (IR) injury in the heart, brain and kidney. However, their exact roles in the liver remain to be defined. Our objective was to investigate the potential effects of BM-MSCs on a hepatic IR rat model during the first 24 h after reperfusion, a crucial period for hepatic IR damage formation. A rat model of normothermic partial hepatic ischemia was obtained by vascular clamping for 60 min. BM-MSCs were transplanted via portal vein injection. Injury severity, oxidative stress response and apoptosis of liver cells were assessed at 2, 6, 12 and 24 h after reperfusion and cell transplantation was evaluated. At 12 and 24 h after reperfusion, rats transplanted with BM-MSCs had significantly lower serum levels of alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST), fewer damaged liver tissues, higher superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and lower malondialdehyde (MDA) levels compared to rats in the sham transplantation group. At 24 h after reperfusion, IR rats transplanted with BM-MSCs had significantly fewer apoptotic hepatocytes, higher levels of B-cell lymphoma 2 (Bcl-2) protein, and lower levels of Bcl-2-associated X (Bax) and caspase-3 (Casp3) proteins compared to sham transplantation rats. In conclusion, BM-MSCs transplanted via the portal vein partially prevent hepatic IR injury by suppressing oxidative stress and inhibiting apoptosis during the first 24 h after reperfusion.