Rika Nishikawa

The tumor-suppressive microRNA-143/145 cluster inhibits cell migration and invasion by targeting GOLM1 in prostate cancer

Our recent study of microRNA (miRNA) expression signature of prostate cancer (PCa) has revealed that the microRNA-143/145 (miR-143/145) cluster is significantly downregulated in cancer tissues, suggesting that these cluster miRNAs are candidate tumor suppressors. The aim of this study was to investigate the functional significance of the miR-143/145 cluster in PCa cells and to identify novel targets regulated by these cluster miRNAs in PCa. Restoration of miR-143 or miR-145 in PCa cell lines (PC3 and DU145) revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that Golgi membrane protein 1 (GOLM1) resembling a type II golgi transmembrane protein was a potential target of miR-143/145 cluster target gene. Gene expression studies and luciferase reporter assays showed that GOLM1 was directly regulated by the miR-143/145 cluster. Silencing of GOLM1 resulted in significant inhibition of cell migration and invasion in PCa cells. Furthermore, the expression of GOLM1 was upregulated in cancer tissues by immunohistochemistry. Loss of the tumor-suppressive miR-143/145 cluster enhanced cancer cell migration and invasion in PCa through directly regulating GOLM1. Our data on target genes regulated by the tumor-suppressive miR-143/145 cluster provide new insights into the potential mechanisms of PCa oncogenesis and metastasis.

Tumor-suppressive microRNA-218 inhibits cancer cell migration and invasion via targeting of LASP1 in prostate cancer

Our recent studies of the microRNA (miRNA) expression signature in prostate cancer (PCa) indicated that miRNA‐218 (miR‐218) was significantly downregulated in clinical specimens, suggesting that miR‐218 might act as a tumor‐suppressive miRNA in PCa. The aim of the present study was to investigate the functional significance of miR‐218 in PCa and to identify novel miR‐218‐regulated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR‐218 in PCa cell lines (PC3 and DU145) revealed that this miRNA significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that LIM and SH3 protein 1 (LASP1) is a potential target of miR‐218 regulation. LASP1 is a cytoskeletal scaffold protein that plays critical roles in cytoskeletal organization and cell migration. Luciferase reporter assays showed that miR‐218 directly regulated expression of LASP1. Moreover, downregulating the LASP1 gene significantly inhibited cell migration and invasion in cancer cells, and the expression of LASP1 was upregulated in cancer tissues. We conclude that loss of tumor‐suppressive miR‐218 enhanced cancer cell migration and invasion in PCa through direct regulation of LASP1. Our data on pathways regulated by tumor‐suppressive miR‐218 provide new insight into the potential mechanisms of PCa oncogenesis and metastasis.

Tumor-suppressive microRNA-29s inhibit cancer cell migration and invasion via targeting LAMC1 in prostate cancer

Our recent studies of microRNA (miRNA) expression signatures revealed that microRNA-29s (miR-29s; including miR-29a/b/c) were significantly downregulated in prostate cancer (PCa) and was a putative tumor-suppressive miRNA family in PCa. Herein, we aimed to investigate the functional significance of miR-29 in cancer cells and to identify novel miR-29s-mediated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR-29s in PC3 and DU145 cell lines revealed significant inhibition of cancer cell migration and invasion. To identify miR-29s-mediated molecular pathways and targets, we used gene expression data and in silico database analysis. Our analysis demonstrated that miR-29s modulated the focal adhesion pathway. Moreover, the laminin γ1 (LAMC1) gene was a candidate target of miR-29s regulation. Luciferase reporter assays showed that miR-29s directly regulated LAMC1. Silencing of LAMC1 significantly inhibited cell migration and invasion in cancer cells, and LAMC1 was upregulated in PCa. miR-29s acted as tumor suppressors, contributing to cancer cell migration and invasion and directly targeting laminin signaling. Recognition of tumor-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of PCa oncogenesis and metastasis, and suggests novel therapeutic strategies for treating this disease.

Tumor‐suppressive microRNA‐223 inhibits cancer cell migration and invasion by targeting ITGA3/ITGB1 signaling in prostate cancer

Analysis of microRNA (miRNA) expression signatures in prostate cancer (PCa) and castration‐resistant PCa has revealed that miRNA‐223 is significantly downregulated in cancer tissues, suggesting that miR‐223 acts as a tumor‐suppressive miRNA by targeting oncogenes. The aim of this study was to investigate the functional roles of miR‐223 and identify downstream oncogenic targets regulated by miR‐223 in PCa cells. Functional studies of miR‐223 were carried out to investigate cell proliferation, migration, and invasion using PC3 and PC3M PCa cell lines. Restoration of miR‐223 significantly inhibited cancer cell migration and invasion in PCa cells. In silico database and genome‐wide gene expression analyses revealed that ITGA3 and ITGB1 were direct targets of miR‐223 regulation. Knockdown of ITGA3 and ITGB1 significantly inhibited cancer cell migration and invasion in PCa cells by regulating downstream signaling. Moreover, overexpression of ITGA3 and ITGB1 was observed in PCa clinical specimens. Thus, our data indicated that downregulation of miR‐223 enhanced ITGA3/ITGB1 signaling and contributed to cancer cell migration and invasion in PCa cells. Elucidation of the molecular pathways modulated by tumor‐suppressive miRNAs provides insights into the mechanisms of PCa progression and metastasis.

Tumour-suppressive microRNA-144-5p directly targets CCNE1 / 2 as potential prognostic markers in bladder cancer

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.

MicroRNA expression signature of castration-resistant prostate cancer: the microRNA-221/222 cluster functions as a tumour suppressor and disease progression marker

Background:Our present study of the microRNA (miRNA) expression signature in castration-resistant prostate cancer (CRPC) revealed that the clustered miRNAs microRNA-221 (miR-221) and microRNA-222 (miR-222) are significantly downregulated in cancer tissues. The aim of this study was to investigate the functional roles of miR-221 and miR-222 in prostate cancer (PCa) cells.Methods:A CRPC miRNA signature was constructed by PCR-based array methods. Functional studies of differentially expressed miRNAs were analysed using PCa cells. The association between miRNA expression and overall survival was estimated by the Kaplan–Meier method. In silico database and genome-wide gene expression analyses were performed to identify molecular targets regulated by the miR-221/222 cluster.Results:miR-221 and miR-222 were significantly downregulated in PCa and CRPC specimens. Kaplan–Meier survival curves showed that low expression of miR-222 predicted a short duration of progression to CRPC. Restoration of miR-221 or miR-222 in cancer cells revealed that both miRNAs significantly inhibited cancer cell migration and invasion. Ecm29 was directly regulated by the miR-221/222 cluster in PCa cells.Conclusions:Loss of the tumour-suppressive miR-221/222 cluster enhanced migration and invasion in PCa cells. Our data describing targets regulated by the tumour-suppressive miR-221/222 cluster provide insights into the mechanisms of PCa and CRPC progression.

MicroRNA expression signature of oral squamous cell carcinoma: functional role of microRNA-26a/b in the modulation of novel cancer pathways

Background:MicroRNAs (miRNAs) have been shown to play major roles in carcinogenesis in a variety of cancers. The aim of this study was to determine the miRNA expression signature of oral squamous cell carcinoma (OSCC) and to investigate the functional roles of miR-26a and miR-26b in OSCC cells.Methods:An OSCC miRNA signature was constructed by PCR-based array methods. Functional studies of differentially expressed miRNAs were performed to investigate cell proliferation, migration, and invasion in OSCC cells. In silico database and genome-wide gene expression analyses were performed to identify molecular targets and pathways mediated by miR-26a/b.Results:miR-26a and miR-26b were significantly downregulated in OSCC. Restoration of both miR-26a and miR-26b in cancer cell lines revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Our data demonstrated that the novel transmembrane TMEM184B gene was a direct target of miR-26a/b regulation. Silencing of TMEM184B inhibited cancer cell migration and invasion, and regulated the actin cytoskeleton-pathway related genes.Conclusions:Loss of tumour-suppressive miR-26a/b enhanced cancer cell migration and invasion in OSCC through direct regulation of TMEM184B. Our data describing pathways regulated by tumour-suppressive miR-26a/b provide new insights into the potential mechanisms of OSCC oncogenesis and metastasis.

Dual regulation of receptor tyrosine kinase genes EGFR and c-Met by the tumor-suppressive microRNA-23b/27b cluster in bladder cancer

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.

Tumour‐suppressive microRNA‐224 inhibits cancer cell migration and invasion via targeting oncogenic TPD52 in prostate cancer

Our recent study of the microRNA expression signature of prostate cancer (PCa) revealed that microRNA‐224 (miR‐224) is significantly downregulated in PCa tissues. Here, we found that restoration of miR‐224 significantly inhibits PCa cell migration and invasion. Additionally, we found that oncogenic TPD52 is a direct target of miR‐224 regulation. Silencing of the TPD52 gene significantly inhibits cancer cell migration and invasion. Moreover, TPD52 expression is upregulated in cancer tissues and negatively correlates with miR‐224 expression. We conclude that loss of tumour‐suppressive miR‐224 enhances cancer cell migration and invasion in PCa through direct regulation of oncogenic TPD52.

Identification of tumour suppressive microRNA-451a in hypopharyngeal squamous cell carcinoma based on microRNA expression signature

Background:Hypopharyngeal squamous cell carcinoma (HSCC) has a very poor prognosis because of its high rates of regional and distant metastasis. Identification of differentially expressed miRNAs and their regulated molecular targets in tumour cells might enhance our understanding of the molecular mechanisms of metastasis in human cancers.Methods:A HSCC miRNA signature was constructed by array-based methods. Functional studies of microRNA-451a (miR-451a) and target genes were performed to investigate cell proliferation, migration and invasion by cancer cell lines. To identify miR-451a-regulated molecular targets, we adopted gene expression analysis and in silico database analysis.Results:Our miRNA signature revealed that miR-451a was significantly downregulated in HSCC. Restoration of miR-451a in cancer cell lines revealed that this miRNA significantly inhibited cancer cell migration and invasion. Our data demonstrated that the gene coding for endothelial and smooth muscle cell-derived neuropilin-like molecule (ESDN/DCBLD2) was a direct target of miR-451a regulation. Silencing of ESDN inhibited cell migration and invasion by cancer cells.Conclusions:Loss of tumour suppressive miR-451a enhanced cancer cell migration and invasion in HSCC through direct regulation of ESDN. Our miRNA signature and functional analysis of targets regulated by tumour suppressive miR-451a provide new insights into the potential mechanisms of HSCC oncogenesis and metastasis.