Background:Analysis of a microRNA (miRNA) expression signature of bladder cancer (BC) by deep-sequencing revealed that clustered miRNAs microRNA (miR)-451a, miR-144-3p, and miR-144-5p were significantly downregulated in BC tissues. We hypothesised that these miRNAs function as tumour suppressors in BC. The aim of this study was to investigate the functional roles of these miRNAs and their modulation of cancer networks in BC cells.Methods:The functional studies of BC cells were performed using transfection of mature miRNAs. Genome-wide gene expression analysis, in silico analysis, and dual-luciferase reporter assays were applied to identify miRNA targets. The association between miR-144-5p levels and expression of the target genes was determined, and overall patient survival as a function of target gene expression was estimated by the Kaplan–Meier method.Results:Gain-of-function studies showed that miR-144-5p significantly inhibited cell proliferation by BC cells. Four cell cycle-related genes (CCNE1, CCNE2, CDC25A, and PKMYT1) were identified as direct targets of miR-144-5p. The patients with high CCNE1 or CCNE2 expression had lower overall survival probabilities than those with low expression (P=0.025 and P=0.032).Conclusion:miR-144-5p functions as tumour suppressor in BC cells. CCNE1 and CCNE2 were directly regulated by miR-144-5p and might be good prognostic markers for survival of BC patients.

Patients with lung adenocarcinoma may benefit from recently developed molecular targeted therapies. However, analogous advanced treatments are not available for patients with lung squamous cell carcinoma (lung SCC). The survival rate of patients with the advanced stage of lung SCC remains poor. Exploration of novel lung SCC oncogenic pathways might lead to new treatment protocols for the disease. Based on this concept, we have identified microRNA-(miRNA) mediated oncogenic pathways in lung SCC. It is well known that miR-145-5p (the guide strand) functions as a tumor suppressor in several types of cancer. However, the impact of miR-145-3p (the passenger strand) on cancer cells is still ambiguous. Expression levels of miR-145-5p and miR-145-3p were markedly reduced in cancer tissues, and ectopic expression of these miRNAs inhibited cancer cell aggressiveness, suggesting that both miR-145-3p as well as miR-145-5p acted as antitumor miRNAs. We identified seven putative target genes (MTDH, EPN3, TPD52, CYP27B1, LMAN1, STAT1 and TXNDC12) that were coordinately regulated by miR-145-5p and miR-145-3p in lung SCC. Among the seven genes, we found that metadherin (MTDH) was a direct target of these miRNAs. Kaplan-Meier survival curves showed that high expression of MTDH predicted reduced survival of lung SCC patients. We investigated pathways downstream from MTDH by using genome-wide gene expression analysis. Our data showed that several anti-apoptosis and pro-proliferation genes were involved in pathways downstream from MTDH in lung SCC. Taken together, both strands of miR-145, miR-145-5p and miR-145-3p are functional and play pivotal roles as antitumor miRNAs in lung SCC.

Recent clinical trials of chemotherapeutics for advanced bladder cancer (BC) have shown limited benefits. Therefore, new prognostic markers and more effective treatment strategies are required. One approach to achieve these goals is through the analysis of RNA networks. Our recent studies of microRNA (miRNA) expression signatures revealed that the microRNA-23b/27b (miR-23b/27b) cluster is frequently downregulated in various types of human cancers. However, the functional role of the miR-23b/27b cluster in BC cells is still unknown. Thus, the aim of the present study was to investigate the functional significance of the miR-23b/27b cluster and its regulated molecular targets, with an emphasis on its contributions to BC oncogenesis and metastasis. The expression levels of the miR-23b/27b cluster were significantly reduced in BC clinical specimens. Restoration of mature miR-23b or miR-27b miRNAs significantly inhibited cancer cell migration and invasion, suggesting that these clustered miRNAs function as tumor suppressors. Gene expression data and in silico analysis demonstrated that the genes coding for the epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor (c-Met) were potential targets of the miR-23b/27b cluster. Luciferase reporter assays and western blotting demonstrated that EGFR and c-Met receptor trypsine kinases were directly regulated by these clustered miRNAs. We conclude that the decreased expression of the tumor-suppressive miR-23b/27b cluster enhanced cancer cell proliferation, migration and invasion in BC through direct regulation of EGFR and c-Met signaling pathways. Our data on RNA networks regulated by tumor-suppressive miR-23b/27b provide new insights into the potential mechanisms of BC oncogenesis and metastasis.

Lung cancer is clearly the primary cause of cancer-related deaths worldwide. Recent molecular-targeted strategy has contributed to improvement of the curative effect of adenocarcinoma of the lung. However, such current treatment has not been developed for squamous cell carcinoma (SCC) of the disease. The new genome-wide RNA analysis of lung-SCC may provide new avenues for research and the development of the disease. Our recent microRNA (miRNA) expression signatures of lung-SCC revealed that clustered miRNAs miR-1/133a were significantly reduced in cancer tissues. Here, we found that restoration of both mature miR-1 and miR-133a significantly inhibited cancer cell proliferation, migration and invasion. Coronin-1C (CORO1C) was a common target gene of the miR-1/133a cluster, as shown by the genome-wide gene expression analysis and the luciferase reporter assay. Silencing of CORO1C gene expression inhibited cancer cell proliferation, migration and invasion. Furthermore, CORO1C-regulated molecular pathways were categorized by using si-CORO1C transfectants. Further analysis of novel cancer signaling pathways modulated by the tumor-suppressive cluster miR-1/133a will provide insights into the molecular mechanisms of lung-SCC oncogenesis and metastasis.

Lung cancer remains the most frequent cause of cancer-related death in developed countries. A recent molecular-targeted strategy has contributed to improvement of the remarkable effect of adenocarcinoma of the lung. However, such treatment has not been developed for squamous cell carcinoma (SCC) of the disease. Our recent studies of microRNA (miRNA) expression signatures of human cancers showed that the microRNA-29 family (miR-29a, miR-29b and miR-29c) significantly reduced cancer tissues compared to normal tissues. These findings suggest that miR-29s act as tumor-suppressors by targeting several oncogenic genes. The aim of the study was to investigate the functional significance of miR-29s in lung SCC and to identify miR-29s modulating molecular targets in lung SCC cells. Restoration of all mature members of the miR-29s inhibited cancer cell migration and invasion. Gene expression data combined in silico analysis and luciferase reporter assays demonstrated that the lysyl oxidase-like 2 (LOXL2) gene was a direct regulator of tumor-suppressive miR-29s. Moreover, overexpressed LOXL2 was confirmed in lung SCC clinical specimens, and silencing of LOXL2 inhibited cancer cell migration and invasion in lung SCC cell lines. Our present data suggested that loss of tumor-suppressive miR-29s enhanced cancer cell invasion in lung SCC through direct regulation of oncogenic LOXL2. Elucidation of the novel lung SCC molecular pathways and targets regulated by tumor-suppressive miR-29s will provide new insights into the potential mechanisms of oncogenesis and metastasis of the disease.