MicroRNA-126 inhibits invasion in bladder cancer via regulation of ADAM9

Background:

The miRNA deregulation is commonly observed in human malignancies, where they act as tumour suppressors or oncogenes. Despite the association of several miRNAs with bladder cancer, little is known about the miRNAs that contribute to bladder cancer progression from non-muscle invasive (NMI) to muscle-invasive (MI) disease.

Methods:

We first profiled the expression of miRNAs and mRNAs in a cohort of urothelial carcinomas and further characterised the role of miR-126 in invasion, as it emerged as the most downregulated miRNA between MI and NMI tumours.

Results:

We found that restoration of miR-126 levels attenuated the invasive potential of bladder cancer cells. Mechanistically, we identified the role of miR-126 in invasion through its ability to target ADAM9. Notably, a significant inverse correlation between miR-126 and ADAM9 expression was observed, where ADAM9 was upregulated in MI bladder cancer cells. While knockdown of ADAM9 attenuated the invasiveness of cells with low miR-126 levels, experimental upregulation of ADAM9 recapitulated the invasive phenotype. Furthermore, ADAM9 expression assessed by immunohistochemistry significantly correlated with poor prognosis in patients with urothelial carcinoma.

Conclusions:

In this study we describe the role of miR-126 in bladder cancer progression, identifying miR-126 and ADAM9 as potential clinical biomarkers of disease aggressiveness.     

The miR-143/-145 cluster regulates plasminogen activator inhibitor-1 in bladder cancer

Background:

Upregulation of the proto-oncogene plasminogen activator inhibitor-1 (PAI-1) is a common hallmark of various solid tumours, but the mechanisms controlling its expression are not fully understood.

Methods:

We investigate microRNAs (miRNAs) regulating PAI-1 in a panel of normal bladder urothelial biopsies, superficial Ta bladder tumours and invasive T1–T4 tumours using expression microarrays and qRT–PCR. The prognostic implications of PAI-1 deregulation are established by tissue microarray staining of non-muscle-invasive bladder tumours. MicroRNA repression of PAI-1 is assayed by ectopic miRNA expression, argonaute immunoprecipitation and luciferase assays.

Results:

We found that the miR-143/-145 cluster is downregulated in all stages of bladder cancer and inversely correlated with PAI-1 expression. Mature miR-143 and miR-145 are coordinately expressed, and both directly target the PAI-1 3′UTR, leading to reduced PAI-1 mRNA and protein levels. Furthermore, we show that PAI-1 and miR-145 levels may serve as useful prognostic markers for non-muscle-invasive bladder tumours for which accurate progressive outcome is currently difficult to predict.

Conclusion:

This report provides the first evidence for direct miRNA regulation of PAI-1 in bladder cancer. We also demonstrate mRNA co-targeting by a cluster of non-family miRNAs, and suggest miR-145 and PAI-1 as clinically relevant biomarkers in bladder cancer.     

The functional significance of microRNA-145 in prostate cancer

Background:

MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in numerous cellular processes. Recent studies have shown aberrant expression of miRNAs in prostate cancer tissues and cell lines. On the basis of miRNA microarray data, we found that miR-145 is significantly downregulated in prostate cancer.

Methods and results:

We investigated the expression and functional significance of miR-145 in prostate cancer. The expression of miR-145 was low in all the prostate cell lines tested (PC3, LNCaP and DU145) compared with the normal cell line, PWR-1E, and in cancerous regions of human prostate tissue when compared with the matched adjacent normal. Overexpression of miR-145 in PC3-transfected cells resulted in increased apoptosis and an increase in cells in the G2/M phase, as detected by flow cytometry. Investigation of the mechanisms of inactivation of miR-145 through epigenetic pathways revealed significant DNA methylation of the miR-145 promoter region in prostate cancer cell lines. Microarray analyses of miR-145-overexpressing PC3 cells showed upregulation of the pro-apoptotic gene TNFSF10, which was confirmed by real-time PCR and western analysis.

Conclusion:

One of the genes significantly upregulated by miR-145 overexpression is the proapoptotic gene TNFSF10. Therefore, modulation of miR-145 may be an important therapeutic approach for the management of prostate cancer.     

miR-375 is upregulated in acquired paclitaxel resistance in cervical cancer

Background:

Chemo-resistance is one of the key causal factors in cancer death and emerging evidences suggest that microRNAs (miRNAs) have critical roles in the regulation of chemo-sensitivity in cancers. Cervical cancer is one of the most common malignancies in women and insensitive to chemotherapy clinically.

Methods:

The differentially expressed miRNAs in cervical squamous cell carcinoma tissues were screened by using a microarray platform (μParaflo Sanger miRBase release 13.0). The expression of miR-375 was determined by stem-loop RT–PCR using 23 clinical cervical cancer samples and 2 cervical cancer cell lines. We exogenously upregulated miR-375 expression in SiHa and Caski cells using a pre-miRNA lentiviral vector transfection and observed its impact on paclitaxel sensitivity using MTS. The cells that stably overexpressed miR-375 were subcutaneously injected into mice to determine tumour growth and chemo-sensitivity in vivo.

Results:

Twenty-one differentially expressed miRNAs were found by miRNA microarray between pro- and post-paclitaxel cervical cancer tissues. Of those, miR-375 showed consistent high expression levels across paclitaxel-treated cervical cells and tissues. Paclitaxel induced upregulated miR-375 expression in a clear dose-dependent manner. Forced overexpression of miR-375 in cervical cancer cells decreased paclitaxel sensitivity in vitro and in vivo.

Conclusion:

Collectively, our results suggest that miR-375 might be a therapeutic target in paclitaxel-resistant cervical cancer.     

miR-489 is a tumour-suppressive miRNA target PTPN11 in hypopharyngeal squamous cell carcinoma (HSCC)

Background:

Hypopharyngeal squamous cell carcinoma (HSCC) is an aggressive malignancy with one of the worst prognoses among all head and neck cancers. Greater understanding of the pertinent molecular oncogenic pathways could help improve diagnosis, therapy, and prevention of this disease. The aim of this study was to identify tumour-suppressive microRNAs (miRNAs), based on miRNA expression signatures from clinical HSCC specimens, and to predict their biological target genes.

Methods:

Expression levels of 365 human mature miRNAs from 10 HSCC clinical samples were screened using stem-loop real-time quantitative PCR. Downregulated miRNAs were used in cell proliferation assays to identify a tumour-suppressive miRNA. Genome-wide gene expression analyses were then performed to identify the target genes of the tumour-suppressive miRNA.

Results:

Expression analysis identified 11 upregulated and 31 downregulated miRNAs. Gain-of-function analysis of the downregulated miRNAs revealed that miR-489 inhibited cell growth in all head and neck cancer cell lines examined. The gene PTPN11 coding for a cytoplasmic protein tyrosine phosphatase containing two Src Homology 2 domains was identified as a miR-489-targeted gene. Knockdown of PTPN11 resulted in the inhibition of cell proliferation in head and neck SCC cells.

Conclusion:

Identification of the tumour-suppressive miRNA miR-489 and its target, PTPN11, might provide new insights into the underlying molecular mechanisms of HSCC.     

MicroRNA-143 targets DNA methyltransferases 3A in colorectal cancer

Background:

MicroRNAs (miRNAs) are 19-25-nucleotides regulatory non-protein-coding RNA molecules that regulate the expressions of a wide variety of genes, including some involved in cancer development. In this study, we investigated the possible role of miR-143 in colorectal cancer (CRC).

Methods:

Expression levels of human mature miRNAs were examined using real-time PCR-based expression arrays on paired colorectal carcinomas and adjacent non-cancerous colonic tissues. The downregulation of miR-143 was further evaluated in colon cancer cell lines and in paired CRC and adjacent non-cancerous colonic tissues by qRT–PCR. Potential targets of miR-143 were defined. The functional effect of miR-143 and its targets was investigated in human colon cancer cell lines to confirm miRNA–target association.

Results:

Both real-time PCR-based expression arrays and qRT–PCR showed that miR-143 was frequently downregulated in 87.5% (35 of 40) of colorectal carcinoma tissues compared with their adjacent non-cancerous colonic tissues. Using in silico predictions, DNA methyltranferase 3A (DNMT3A) was defined as a potential target of miR-143. Restoration of the miR-143 expression in colon cell lines decreased tumour cell growth and soft-agar colony formation, and downregulated the DNMT3A expression in both mRNA and protein levels. DNMT3A was shown to be a direct target of miR-143 by luciferase reporter assay. Furthermore, the miR-143 expression was observed to be inversely correlated with DNMT3A mRNA and protein expression in CRC tissues.

Conclusion:

Our findings suggest that miR-143 regulates DNMT3A in CRC. These findings elucidated a tumour-suppressive role of miR-143 in the epigenetic aberration of CRC, providing a potential development of miRNA-based targeted approaches for CRC therapy.     

miRNA profiling in metastatic renal cell carcinoma reveals a tumour-suppressor effect for miR-215

Background:

Renal cell carcinoma (RCC) is the most common neoplasm of the adult kidney. Metastatic RCC is difficult to treat. The 5-year survival rate for metastatic RCC is ⩽10%. Recently, microRNAs (miRNAs) have been shown to have a role in cancer metastasis and potential as prognostic biomarkers in cancer.

Method:

We performed a miRNA microarray to identify a miRNA signature characteristic of metastatic compared with primary RCCs. We validated our results by quantitative real-time PCR. We performed experimental and bioinformatic analyses to explore the involvement of miR-215 in RCC progression and metastasis.

Results:

We identified 65 miRNAs that were significantly altered in metastatic compared with primary RCCs. We validated our results by examining the expression of miR-10b, miR-126, miR-196a, miR-204 and miR-215, in two independent cohorts of patients. We showed that overexpression of miR-215 decreased cellular migration and invasion in an RCC cell line model. In addition, through gene expression profiling, we identified direct and indirect targets of miR-215 that can contribute to tumour metastasis.

Conclusion:

Our analysis showed that miRNAs are altered in metastatic RCCs and can contribute to kidney cancer metastasis through different biological processes. Dysregulated miRNAs represent potential prognostic biomarkers and may have therapeutic applications in kidney cancer.     

The tumour-suppressive function of miR-1 and miR-133a targeting TAGLN2 in bladder cancer

Background:

On the base of the microRNA (miRNA) expression signature of bladder cancer (BC), we found that miR-1 and miR-133a were significantly downregulated in BC. In this study, we focussed on the functional significance of miR-1 and miR-133a in BC cell lines and identified a molecular network of these miRNAs.

Methods and results:

We investigated the miRNA expression signature of BC clinical specimens and identified several downregulated miRNAs (miR-133a, miR-204, miR-1, miR-139-5p, and miR-370). MiR-1 and miR-133a showed potential role of tumour suppressors by functional analyses of BC cells such as cell proliferation, apoptosis, migration, and invasion assays. Molecular target searches of these miRNAs showed that transgelin 2 (TAGLN2) was directly regulated by both miR-1 and miR-133a. Silencing of TAGLN2 study demonstrated significant inhibitions of cell proliferation and increase of apoptosis in BC cell lines. The immunohistochemistry showed a positive correlation between TAGLN2 expression and tumour grade in clinical BC specimens.

Conclusions:

The downregulation of miR-1 and miR-133a was a frequent event in BC, and these miRNAs were recognised as tumour suppressive. TAGLN2 may be a target of both miRNAs and had a potential oncogenic function. Therefore, novel molecular networks provided by miRNAs may provide new insights into the underlying molecular mechanisms of BC.     

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.     

Identifying microRNAs regulating B7-H3 in breast cancer: the clinical impact of microRNA-29c

Background:

B7-H3, an immunoregulatory protein, is overexpressed in several cancers and is often associated with metastasis and poor prognosis. Here, our aim was to identify microRNAs (miRNAs) regulating B7-H3 and assess their potential prognostic implications in breast cancer.

Methods:

MicroRNAs targeting B7-H3 were identified by transfecting two breast cancer cell lines with a library of 810 miRNA mimics and quantifying changes of B7-H3 protein levels using protein lysate microarrays. For validations we used western immunoblotting and 3′-UTR luciferase assays. Clinical significance of the miRNAs was assayed by analysing whether their expression levels correlated with outcome in two cohorts of breast cancer patients (142 and 81 patients).

Results:

We identified nearly 50 miRNAs that downregulated B7-H3 protein levels. Western immunoblotting validated the impact of the 20 most effective miRNAs. Thirteen miRNAs (miR-214, miR-363*, miR-326, miR-940, miR-29c, miR-665, miR-34b*, miR-708, miR-601, miR-124a, miR-380-5p, miR-885-3p, and miR-593) targeted B7-H3 directly by binding to its 3′-UTR region. Finally, high expression of miR-29c was associated with a significant reduced risk of dying from breast cancer in both cohorts.

Conclusions:

We identified miRNAs efficiently downregulating B7-H3 expression. The expression of miR-29c correlated with survival in breast cancer patients, suggesting a tumour suppressive role for this miRNA.     

MicroRNA-145 inhibits tumour growth and metastasis in colorectal cancer by targeting fascin-1

Background:

Recent studies have reported miR-145 dysregulated in colorectal cancer (CRC). In this study, miR-145 profiles were compared between CRC and corresponding non-tumour tissues.

Methods:

The expression levels of miR-145 were analysed in CRC cell lines and tumour tissues by real-time PCR. A luciferase reporter assay confirmed direct targets. The functional effects of miR-145 were examined in transfected CRC cells in vitro and in vivo using established assays.

Results:

Downregulation of miR-145 was detected in most primary CRC tumours, and was significantly correlated with a more aggressive phenotype of CRC in patients. In CRC cell lines, ectopic overexpression of miR-145 inhibited cell proliferation, motility and invasion in vitro. Stable overexpression of miR-145 suppressed tumour growth and pulmonary metastasis in vivo. Further studies indicated that miR-145 may directly interact with the 3′-untranslated region (3′-UTR) of Fascin-1 messenger RNA (mRNA), downregulating its mRNA and protein expression levels. In clinical specimens, Fascin-1 expression was negatively correlated with miR-145 expression.

Conclusions:

MiR-145 has a critical role in the inhibition of invasive and metastatic capacities of CRC, probably through directly targeting Fascin-1. This miRNA may be involved in the development and progression of CRC.     

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.     

Deregulated microRNAs in gastric cancer tissue-derived mesenchymal stem cells: novel biomarkers and a mechanism for gastric cancer

Background:

MicroRNAs (miRNAs) are involved in gastric cancer development and progression. However, the expression and role of miRNAs in gastric cancer stromal cells are still unclear.

Methods:

The miRNAs differentially expressed in gastric cancer tissue-derived mesenchymal stem cells (GC-MSCs) relative to adjacent non-cancerous tissue-derived MSCs (GCN-MSCs) and in cancer tissues relative to adjacent non-cancerous tissues were screened using miRNA microarray and validated by quantitative RT–PCR. The impact of GC-MSCs on HGC-27 cells was observed in vitro using colony formation and transwell assays, and these cells were subcutaneously co-injected into mice to assess tumour growth in vivo. Exogenous downregulation of miR-221 expression in cells was achieved using an miRNA inhibitor.

Results:

miR-214, miR-221 and miR-222 were found to be commonly upregulated in GC-MSCs and cancer tissues. Their levels were tightly associated with lymph node metastasis, venous invasion and the TNM stage. Gastric cancer tissue-derived mesenchymal stem cells significantly promoted HGC-27 growth and migration and increased the expression of miR-221 via paracrine secretion, and the targeted inhibition of miR-221 in GC-MSCs could block its tumour-supporting role. GC-MSC-derived exosomes were found to deliver miR-221 to HGC-27 cells and promoted their proliferation and migration.

Conclusions:

Gastric cancer tissue-derived mesenchymal stem cells favour gastric cancer progression by transferring exosomal miRNAs to gastric cancer cells, thus providing a novel mechanism for the role of GC-MSCs and new biomarkers for gastric cancer.     

Tumour suppressors miR-1 and miR-133a target the oncogenic function of purine nucleoside phosphorylase (PNP) in prostate cancer

Background:

Our recent analyses of miRNA expression signatures showed that miR-1 and miR-133a were significantly reduced in several types of cancer. Interestingly, miR-1 and miR-133a are located on the same chromosomal locus in the human genome. We examined the functional significance of miR-1 and miR-133a in prostate cancer (PCa) cells and identified the novel molecular targets regulated by both miR-1 and miR-133a.

Methods and Results:

The expression levels of miR-1 and miR-133a were significantly downregulated in PCa compared with non-PCa tissues. Restoration of miR-1 or miR-133a in PC3 and DU145 cells revealed significant inhibition of proliferation, migration, and invasion. Molecular target identification by genome-wide gene expression analysis and luciferase reporter assay showed that purine nucleoside phosphorylase (PNP) was directly regulated by both miRNAs. Silencing of the PNP gene inhibited proliferation, migration, and invasion in both PC3 and DU145 cells. Immunohistochemistry detected positive staining of PNP in PCa specimens.

Conclusions:

Downregulation of miR-1 and miR-133a was a frequent event in PCa and both function as tumour suppressors. The PNP is a novel target gene of both miRNAs and potentially functions as an oncogene. Therefore, identification of novel molecular networks regulated by miRNAs may provide new insights into the underlying causes of PCa oncogenesis.     

Novel diagnostic value of circulating miR-18a in plasma of patients with pancreatic cancer

Background:

Several recent studies have demonstrated that microRNAs (miRNAs) are stably detectable in the plasma/serum. We hypothesised that miR-18a in the plasma is a potential biomarker in patients with pancreatic cancer.

Methods:

miR-18a is located in the miR-17–92 cluster and reported to be highly expressed in pancreatic cancer tissues. This study was divided into three parts: (1) Confirmation of higher miR-18a levels in primary pancreatic cancer tissues and cell lines than in normal pancreatic tissues and a human fibroblast cell line. (2) Evaluation of the plasma miR-18a assay using quantitative RT–PCR by comparing plasma results obtained from 36 patients with pancreatic cancer and from 30 healthy volunteers. (3) Evaluation of the assay for monitoring tumour dynamics in patients with pancreatic cancer.

Results:

(1) The expression of miR-18a was significantly higher in pancreatic cancer tissues (P=0.012) and pancreatic cancer cell lines (P=0.015) than in normal tissues and fibroblasts. (2) Plasma concentrations of miR-18a were significantly higher in pancreatic cancer patients than in controls (P<0.0001). The value of the area under the receiver-operating characteristic curve (AUC) was 0.9369. (3) Plasma levels of miR-18a were significantly lower in postoperative samples than in preoperative samples (P=0.0077).

Conclusion:

Circulating miR-18a might provide new complementary tumour markers for pancreatic cancer.     

miR-19a acts as an oncogenic microRNA and is up-regulated in bladder cancer

Background

The application of microRNAs (miRNAs) as potential biomarkers and therapy targets has been widely investigated in many kinds of cancers. The discovery of tumor associated miRNAs in serum of patients supported the use of plasma/serum miRNAs as noninvasive means of cancer detection. However, the aberrant expression of miRNAs in bladder cancer patients and their intensive roles and mechanisms in bladder cancer are poorly understood.

Methods

Taqman probe stem-loop real-time PCR was used to accurately measure the levels of miR-19a in bladder cancer cell lines, 100 pairs of bladder cancer tissues and the adjacent non-neoplastic tissues and also the plasma collected from bladder cancer patients and normal controls. miR-19a mimics and inhibitors were transfected into bladder cancer cells to investigate its role on regulating cell proliferation which was measured by CCK-8 and colony formation assay. The target of miR-19a was identified by western blot and whether its regulatory role depends on its target was improved by a rescue experiment with miR-19a mimic and PTEN expression plasmid.

Results

miR-19a was significantly up-regulated in bladder cancer tissues and high-level of miR-19a was correlative with more aggressive phenotypes of bladder cancer. Meanwhile, gain or loss of function of miR-19a demonstrated that miR-19a can promote cell growth of bladder cancer cells and the further mechanism studies indicated that its oncogenic role was dependent on targeting PTEN. Furthermore, investigation of miR-19a expression in the plasma of bladder cancer patients showed that miR-19a was also increased in plasma of bladder cancer patients which strongly supported miR-19a could be developed as potential diagnostic marker of bladder cancer.

Conclusions

Our data indicated that miR-19a might act as an oncogenic microRNA in bladder cancer and was significantly up-regulated in bladder cancer carcinogenesis. The oncogenic role of miR19a in bladder cancer was dependent on targeting PTEN.     

The role of miRNAs in human papilloma virus (HPV)-associated cancers: bridging between HPV-related head and neck cancer and cervical cancer

Background:

Although the role of human papilloma virus (HPV) in cervical squamous cell carcinoma (CSCC) is well established, the role in head and neck SCC (HNSCC) is less clear. MicroRNAs (miRNAs) have a role in the cancer development, and HPV status may affect the miRNA expression pattern in HNSCC. To explore the influence of HPV in HNSCC, we made a comparative miRNA profile of HPV-positive (HPV+) and HPV-negative (HPV−) HNSCC against CSCC.

Methods:

Fresh frozen and laser microdissected-paraffin-embedded samples obtained from patients with HPV+/HPV− HNSCC, CSCC and controls were used for microarray analysis. Differentially expressed miRNAs in the HPV+ and HPV− HNSCC samples were compared with the differentially expressed miRNAs in the CSCC samples.

Results:

Human papilloma virus positive (+) HNSCC had a distinct miRNA profile compared with HPV− HNSCC. Significantly more similarity was seen between HPV+ HNSCC and CSCC than HPV− and CSCC. A set of HPV core miRNAs were identified. Of these especially the miR-15a/miR-16/miR195/miR-497 family, miR-143/miR-145 and the miR-106-363 cluster appear to be important within the known HPV pathogenesis.

Conclusion:

This study adds new knowledge to the known pathogenic pathways of HPV and substantiates the oncogenic role of HPV in subsets of HNSCCs.     

miR-145 and miR-133a function as tumour suppressors and directly regulate FSCN1 expression in bladder cancer

Background:

We have recently identified down-regulated microRNAs including miR-145 and miR-133a in bladder cancer (BC). The aim of this study is to determine the genes targeted by miR-145, which is the most down-regulated microRNA in BC.

Methods:

We focused on fascin homologue 1 (FSCN1) from the gene expression profile in miR-145 transfectant. The luciferase assay was used to confirm the actual binding sites of FSCN1 mRNA. Cell viability was evaluated by cell growth, wound-healing, and matrigel invasion assays. BC specimens were subjected to immunohistochemistry of FSCN1 and in situ hybridisation of miR-145.

Results:

The miR-133a as well as miR-145 had the target sequence of FSCN1 mRNA by the database search, and both microRNAs repressed the mRNA and protein expression of FSCN1. The luciferase assay revealed that miR-145 and miR-133a were directly bound to FSCN1 mRNA. Cell viability was significantly inhibited in miR-145, miR-133a, and si-FSCN1 transfectants. In situ hybridisation revealed that miR-145 expression was markedly repressed in the tumour lesion in which FSCN1 was strongly stained. The immunohistochemical score of FSCN1 in invasive BC (n=46) was significantly higher than in non-invasive BC (n=20) (P=0.0055).

Conclusion:

Tumour suppressive miR-145 and miR-133a directly control oncogenic FSCN1 in BC.