MicroRNA-539 functions as a tumour suppressor in prostate cancer via the TGF-β/Smad4 signalling pathway by down-regulating DLX1.

Prostate cancer (PCa) is the second leading cause of cancer-related death in males, primarily due to its metastatic potential. The present study aims to identify the expression of microRNA-539 (miR-539) in PCa and further investigate its functional relevance in PCa progression both in vitro and in vivo. Initially, microarray analysis was conducted to obtain the differentially expressed gene candidates and the regulatory miRNAs, after which the possible interaction between the two was determined. Next, ectopic expression and knock-down of the levels of miR-539 were performed in PCa cells to identify the functional role of miR-539 in PCa pathogenesis, followed by the measurement of E-cadherin, vimentin, Smad4, c-Myc, Snail1 and SLUG expression, as well as proliferation, migration and invasion of PCa cells. Finally, tumour growth was evaluated in nude mice through in vivo experiments. The results found that miR-539 was down-regulated and DLX1 was up-regulated in PCa tissues and cells. miR-539 was also found to target and negatively regulate DLX1 expression, which resulted in the inhibition of the TGF-β/Smad4 signalling pathway. Moreover, the up-regulation of miR-539 or DLX1 gene silencing led to the inhibition of PCa cell proliferation, migration, invasion, EMT and tumour growth, accompanied by increased E-cadherin expression and decreased expression of vimentin, Smad4, c-Myc, Snail1 and SLUG. In conclusion, the overexpression of miR-539-mediated DLX1 inhibition could potentially impede EMT, proliferation, migration and invasion of PCa cells through the blockade of the TGF-β/Smad4 signalling pathway, highlighting a potential miR-539/DLX1/TGF-β/Smad4 regulatory axis in the treatment of PCa.

Sun B ，Fan Y ，Yang A ，Liang L ，Cao J ... -  《-》

MicroRNA-506 inhibits tumor growth and metastasis in nasopharyngeal carcinoma through the inactivation of the Wnt/β-catenin signaling pathway by down-regulating LHX2.

Liang TS ，Zheng YJ ，Wang J ，Zhao JY ，Yang DK ，Liu ZS ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

Role of miR-218-GREM1 axis in epithelial-mesenchymal transition of oral squamous cell carcinoma: An in vivo and vitro study based on microarray data.

Oral squamous cell carcinoma (OSCC) is a prevalent cancer that develops in the head and neck area and has high annual mortality despite optimal treatment. microRNA-218 (miR-218) is a tumour inhibiting non-coding RNA that has been reported to suppress the cell proliferation and invasion in various cancers. Thus, our study aims to determine the mechanism underlying the inhibitory role of miR-218 in OSCC. We conducted a bioinformatics analysis to screen differentially expressed genes in OSCC and their potential upstream miRNAs. After collection of surgical OSCC tissues, we detected GREM1 expression by immunohistochemistry, RT-qPCR and Western blot analysis, and miR-218 expression by RT-qPCR. The target relationship between miR-218 and GREM1 was assessed by dual-luciferase reporter gene assay. After loss- and gain-of-function experiments, OSCC cell proliferation, migration and invasion were determined by MTT assay, scratch test and Transwell assay, respectively. Expression of TGF-β1, Smad4, p21, E-cadherin, Vimentin and Snail was measured by RT-qPCR and Western blot analysis. Finally, effects of miR-218 and GREM1 on tumour formation and liver metastasis were evaluated in xenograft tumour-bearing nude mice. GREM1 was up-regulated, and miR-218 was down-regulated in OSCC tissues, and GREM1 was confirmed to be the target gene of miR-218. Furthermore, after up-regulating miR-218 or silencing GREM1, OSCC cell proliferation, migration and invasion were reduced. In addition, expression of TGF-β signalling pathway-related genes was diminished by overexpressing miR-218 or down-regulating GREM1. Finally, up-regulated miR-218 or down-regulated GREM1 reduced tumour growth and liver metastasis in vivo. Taken together, our findings suggest that the overexpression of miR-218 may inhibit OSCC progression by inactivating the GREM1-dependent TGF-β signalling pathway.

Wang Y ，Jiang Y ，Chen L 《-》

MicroRNA-362 negatively and positively regulates SMAD4 expression in TGF-β/SMAD signaling to suppress cell migration and invasion.

Cell migration and invasion are modulated by epithelial-to-mesenchymal transition (EMT) and the reverse MET process. Despite the detection of microRNA-362 (miR-362, both the miR-362-5p and -3p species) in cancers, none of the identified miR-362 targets is a mesenchymal or epithelial factor to link miR-362 with EMT/MET and metastasis. Focusing on the TGF-β/SMAD signaling pathway in this work, luciferase assays and western blot data showed that miR-362 targeted and negatively regulated expression of SMAD4 and E-cadherin, but not SNAI1, which is regulated by SMAD4. However, miR-362 knockdown also down-regulated SMAD4 and SNAI1, but up-regulated E-cadherin expression. Wound-healing and transwell assays further showed that miR-362 knockdown suppressed cell migration and invasion, effects which were reversed by over-expressing SMAD4 or SNAI1, or by knocking down E-cadherin in the miR-362 knockdown cells. In orthotopic mice, miR-362 knockdown inhibited metastasis, and displayed the same SMAD4 and E-cadherin expression profiles in the tumors as in the in vitro studies. A scheme is proposed to integrate miR-362 negative regulation via SMAD4, and to explain miR-362 positive regulation of SMAD4 via miR-362 targeting of known SMAD4 suppressors, BRK and DACH1, which would have resulted in SMAD4 depletion and annulment of subsequent involvement in TGF-β signaling actions. Hence, miR-362 both negatively and positively regulates SMAD4 expression in TGF-β/SMAD signaling pathway to suppress cell motility and invasiveness and metastasis, and may explain the reported clinical association of anti-miR-362 with suppressed metastasis in various cancers. MiR-362 knockdown in miR-362-positive cancer cells may be used as a therapeutic strategy to suppress metastasis.

Cheng HP ，Huang CJ ，Tsai ML ，Ong HT ，Cheong SK ，Choo KB ，Chiou SH ... -  《-》

The involvement of FBP1 in prostate cancer cell epithelial mesenchymal transition, invasion and metastasis by regulating the MAPK signaling pathway.

Zhang YP ，Liu KL ，Yang Z ，Lu BS ，Qi JC ，Han ZW ，Yin YW ，Zhang M ，Chen DM ，Wang XW ，Li W ，Xin H ... -  《-》