No abstract

MicroRNAs (miRNAs) play important roles in the regulation of various tumor biological processes including proliferation and apoptosis. MiR-377 has been implicated in many types of cancer, whereas its expressional feature and potential biological function in pancreatic ductal adenocarcinoma (PDAC) remains unclear. In this study, we scanned the global miRNA expression profiles in PDAC from The Cancer Genome Atlas (TCGA) and found miR-377 was down-regulated significantly in PDAC. Then, its expression was measured in both pancreatic cancer tissues and cells; the data showed that miR-377 was de-regulated and inversely correlated with pathologic parameters of tumor growth or metastasis. We generated PDAC cell lines with stable overexpression or inhibition of miR-377, and our results indicated that miR-377 up-regulation significantly promoted cell viability, proliferation, and migration in PDAC cells, and also induced cell apoptosis and cell cycle arrest simultaneously. Binding-site predictions by bioinformatics showed that Pim-3 might be a potential target of miR-377. Luciferase reporter assay ulteriorly identified that miR-377 suppressed Pim-3 expression by binding the 3'-UTR. In tumor tissues, we also showed that the Pim-3 expression was inversely correlated with that of miR-377. Furthermore, stable ectopic miR-377 expression in pancreatic cancer cell lines suppressed Pim-3 expression, leading to the attenuation of Bad phosphorylation level at its Ser and promoting cell apoptosis. Overall, these results reveal that miR-377 may have tumor growth suppression function by down-regulating Pim-3 kinase expression to inhibit both pancreatic tumor growth and migration, and induce cell apoptosis. Hence, miR-377 may be a potential diagnostic marker and therapeutic target.

Research advances and analysis in the non-protein coding part of the human genome have suggested that microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are associated with tumor initiation, growth and metastasis. Accumulating studies have demonstrated that a class of miRNAs and lncRNAs are dysregulated in hepatocellular carcinoma (HCC) and closely associated with tumorigenesis, diagnosis and prognosis. In the present study, integrative analysis of published data on multi-level Gene Expression Omnibus (GEO) and a bioinformatics computational approach were used to predict regulatory mechanism networks among differentially expressed mRNAs, miRNAs, and lncRNAs. Firstly, nine microarray expression data sets of mRNAs, miRNAs, and lncRNAs associated with HCC were collected from GEO datasets. Secondly, a total of 628 mRNAs, 15 miRNAs, and 49 lncRNAs were differentially expressed in this integrative analysis. Following this, mRNA, miRNA and lncRNA regulatory or co-expression networks were constructed. From the construction of the regulatory networks, five miRNAs and ten lncRNAs were identified as key differentially expressed noncoding RNAs associated with HCC progression. Finally, the regulatory effects of ten lncRNAs and miRNAs were validated. The study provides a novel insight into the understanding of the transcriptional regulation of HCC, and differentially expressed lncRNAs targeted and regulated by miRNAs were identified and validated in HCC specimens and cell lines.

Transmembrane and ubiquitin-like domain-containing 1 (Tmub1) inhibits hepatocyte proliferation during liver regeneration, but its role in hepatocellular carcinoma (HCC) has yet to be revealed. In this study, we show that the levels of Tmub1 were significantly lower in HCC tissues and cells than they were in adjacent tissues and normal hepatic cells, and the low levels of Tmub1 indicated a poor prognosis in HCC patients. Xenograft growth assay revealed that Tmub1 represses HCC growth in vivo . In addition, Tmub1 formed a protein complex with apoptosis-associated protein tumor protein 63 (p63), especially with the ΔN isoforms (ΔNp63α, β, and γ). Further loss- and gain-of-function analyses indicated that Tmub1 promotes apoptosis of Hep3B and MHCC-LM3 cells. Tmub1 decreased the protein expression of ΔNp63, and the pro-apoptotic effect of Tmub1 can be reversed by ΔNp63 isoforms (α, β, and γ). Additionally, we report that Tmub1 promotes the ubiquitination and degradation of ΔNp63 proteins. Finally, we confirmed in HCC tissues that Tmub1 is negatively correlated with ΔNp63 and positively correlated with the level of apoptosis. Taken together, Tmub1 suppresses HCC by enhancing the ubiquitination and degradation of ΔNp63 isoforms to induce HCC cell apoptosis. These findings provide a potential strategy for the management of HCC.