BackgroundMultidrug resistance is the main obstacle for hepatocellular carcinoma (HCC) treatment. miR-32-5p is involved in HCC progression but its function in multidrug resistance is still unclear. Here we aim to find out the function of miR-32-5p in inducing multidrug resistance and its underlying mechanisms of transforming sensitive cell to resistant cell.MethodsWe detected the expression of miR-32-5p and PTEN in the multidrug-resistant cell line (Bel/5-FU) and the sensitive cell line (Bel7402), HCC and para-carcinoma liver tissues through real-time PCR. Dual-luciferase reporter assay verified PTEN is the target of miR-32-5p. Exosomes from sensitive and multidrug resistant cell line were obtained and confirmed through ultracentrifuge and Nano Analyzer. Gain- and loss-of-function experiments, rescue experiments, a PI3K/Akt pathway inhibitor, an exosome biogenesis inhibitor, and nude mice xenograft models were used to determine the underlying mechanisms of miR-32-5p and PTEN, as well as exosomal miR-32-5p in inducing multidrug resistance in vitro and in vivo.ResultsmiR-32-5p was significantly elevated but PTEN was reduced in Bel/5-FU. An inverse correlation between miR-32-5p and PTEN was confirmed in HCC cell lines and patients; moreover, high expression of miR-32-5p and low expression of PTEN were positively associated with poor prognosis. Over-expression of miR-32-5p activated the PI3K/Akt pathway by suppressing PTEN and induced multidrug resistance via exosomes through promoting angiogenesis and epithelial-mesenchymal transition (EMT).ConclusionsOur study demonstrated that the multidrug-resistant cell, Bel/5-FU delivers miR-32-5p to sensitive cell, Bel7402 by exosomes and activates the PI3K/Akt pathway to further induce multidrug resistance by modulating angiogenesis and EMT.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-0677-7) contains supplementary material, which is available to authorized users.
MicroRNA‐155‐5p (miR‐155‐5p) has been reported to play an oncogenic role in different human malignancies; however, its role in hepatocellular carcinoma (HCC) progression is not clearly understood. In this study, we used real‐time PCR in 20 rats with chemically‐induced HCC, 28 human HCC tissues, and the matched paracarcinoma tissues, and HCC cell lines to determine the expression patterns of miR‐155‐5p and PTEN mRNA. Algorithm‐based and experimental strategies, such as dual luciferase gene reporter assays, real‐time PCR and western blots were used to identify PTEN as a candidate miR‐155‐5p target. Gain‐ and loss‐of‐function experiments and administration of a PI3K/Akt pathway inhibitor (wortmannin) were used to identify the effects of miR‐155‐5p and PTEN in MTT assays, flow cytometric analysis, wound healing assays and transwell assays. The results showed that miR‐155‐5p was highly overexpressed; however, PTEN was underexpressed in the HCC rat models, human HCC tissues and cell lines. In addition, miR‐155‐5p upregulation and PTEN downregulation were significantly associated with TNM stage (P < 0.05). Through in vitro experiments, we found that miR‐155‐5p promoted proliferation, invasion and migration, but inhibited apoptosis in HCC by directly targeting the 3′‐UTR of PTEN. Western blots showed that miR‐155‐5p inactivated Bax and caspase‐9, but activated Bcl‐2 to inhibit apoptosis, and it activated MMP to promote migration and invasion via the PI3K/Akt pathway. A xenograft tumor model was used to demonstrate that miR‐155‐5p targets PTEN and activates the PI3K/Akt pathway in vivo as well. Our study highlighted the importance of miR‐155‐5p and PTEN associated with aggressive HCC both in vitro and in vivo.
Introduction: Non-small cell lung cancer (NSCLC) is the most common malignant tumor, and its recurrence and metastasis are the main causes of death. Recently, there is evidence that tumor derived exosomes play an important role in the occurrence and development of NSCLC. Objective’s methods: First, the expression of miR-185-5p and RAB35 in NSCLC tissues, paracancerous tissues, NSCLC cell lines and normal human bronchial epithelial cell line was detected. Then, a series of gain-and loss-of-function assays were performed to validate the effects of miR-185-5p or RAB35 effects on A549 and H2170 cells proliferation, migration and invasion. Next, online bioinformatics analysis and luciferase reporter were used to predict and validate the targeting relationship of miR-185-5p and RAB35. Finally, tumor cell-derived exosomes with genetic downregulation of RAB35 or overexpression of miR-185-5p were co cultured with their parental cells to verify the regulatory role of RAB35 on exosome secretion and function. Results: In NSCLC tissues and cell lines, miR-185-5p was downregulated, while RAB35 was significantly upregulated. Overexpression of miR-185-5p or knockdown of RAB35 expression inhibited cell proliferation, migration and invasion. Furthermore, we elucidated that RAB35 is a direct target of miR-185-5p. Additionally, exosomes derived from tumor cells restored cell proliferation, migration and invasion, whereas exosomes secreted by tumor cells with downregulation of RAB35 expression or overexpression of miR-185-5p lost their ability to restore cell proliferation, migration and invasion. Conclusions: Our results demonstrate that miR-185-5p inhibits tumor cell-derived exosomes-mediated proliferation, migration and invasion of NSCLC cells by downregulating RAB35 expression.
miR-195-5p has been widely explored in various cancers and is considered as a tumor-suppressive microRNA. However, its roles in human lung cancer pathogenesis are not fully elucidated. In this study, we aimed to explore how miR-195-5p is involved in malignant behaviors of lung adenocarcinoma (LUAD) cells. miR-195-5p expression was examined in the tumor tissues of patients with LUAD and human LUAD cell lines including A549 and PC-9. Thioredoxin reductase 2 (TrxR2) was predicted to be an mRNA target of miR-195-5p using online tools and validated by the Dual-Luciferase Reporter Assay. Lentivirus infection was used for gene overexpression, while gene knockdown was achieved by RNA interference. Cell proliferation was determined by Cell Counting Kit-8 and 5-ethynyl-2′-deoxyuridine methods, and cell migration and invasion were assayed with transwell experiments. Cell apoptosis was determined by annexin V staining-based flow cytometry. The antitumor effects of miR-195-5p were also evaluated in nude mice xenografted with A549 cells. We found that miR-195-5p was lowly expressed in human LUAD cells, and its overexpression markedly suppressed cell proliferation, migration, and invasion and increased the apoptosis of LUAD cells in vitro. TrxR2 knockdown phenocopied the tumor-suppressive effects of miR-195-5p overexpression, while simultaneous TrxR2 overexpression remarkably reversed the effects of miR-195-5p overexpression on malignant behaviors of A549 and PC-9 cells. Additionally, miR-195-5p overexpression inhibited the growth of xenografted A549 tumor in nude mice. Our work verified that miR-195-5p exerts tumor-suppressive functions in LUAD cells through targeting TrxR2 and suggested that the miR-195-5p/TrxR2 axis is a potential biomarker for LUAD therapy.
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