Kenryu Nishiyama

Identification of novel microRNA targets based on microRNA signatures in bladder cancer

MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate protein‐coding genes. To identify miRNAs that have a tumor suppressive function in bladder cancer (BC), 156 miRNAs were screened in 14 BCs, 5 normal bladder epithelium (NBE) samples and 3 BC cell lines. We identified a subset of 7 miRNAs (miR‐145, miR‐30a‐3p, miR‐133a, miR‐133b, miR‐195, miR‐125b and miR‐199a*) that were significantly downregulated in BCs. To confirm these results, 104 BCs and 31 NBEs were subjected to real‐time RT‐PCR‐based experiments, and the expression levels of each miRNA were significantly downregulated in BCs (p < 0.0001 in all). Receiver‐operating characteristic curve analysis revealed that the expression levels of these miRNAs had good sensitivity (>70%) and specificity (>75%) to distinguish BC from NBE. Our target search algorithm and gene‐expression profiling in BCs (Kawakami et al., Oncol Rep 2006;16:521–31) revealed that Keratin7 (KRT7) mRNA was a common target of the downregulated miRNAs, and the mRNA expression levels of KRT7 were significantly higher in BCs than in NBEs (p = 0.0004). Spearman rank correlation analysis revealed significant inverse correlations between KRT7 mRNA expression and each downregulated miRNA (p < 0.0001 in all). Gain‐of‐function analysis revealed that KRT7 mRNA was significantly reduced by transfection of 3 miRNAs (miR‐30‐3p, miR‐133a and miR‐199a*) in the BC cell line (KK47). In addition, significant decreases in cell growth were observed after transfection of 3 miRNAs and si‐KRT7 in KK47, suggesting that miR‐30‐3p, miR‐133a and miR‐199a* may have a tumor suppressive function through the mechanism underlying transcriptional repression of KRT7.

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.

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.

MiR‐96 and miR‐183 detection in urine serve as potential tumor markers of urothelial carcinoma: correlation with stage and grade, and comparison with urinary cytology

A new diagnostic marker for urothelial carcinoma (UC) is needed to avoid painful cystoscopy during the initial diagnosis and follow‐up period. However, the current urine markers are useless because of the low sensitivities and specificities for UC detection. MiR‐96 and miR‐183 were differentially upregulated microRNA in our previous microRNA screening for UC. The expression levels of miR‐96 and miR‐183 in the urine samples were significantly higher in 100 UC than in healthy controls (miR‐96, P = 0.0059; and miR‐183, P = 0.0044). The receiver‐operating characteristic curve analyses demonstrated that each microRNA had good sensitivity and specificity for distinguishing UC patients from non‐UC patients (miR‐96, 71.0% and 89.2%; and miR‐183, 74.0% and 77.3%). Our cohort included 78 UC patients who had undergone urinary cytology. MiR‐96 was positively detected in 27 of 44 patients who had had a “negative” urinary cytology diagnosis. We combined the miR‐96 detection data with the urinary cytology data, and diagnosed 61 of 78 cases as UC; sensitivity rose from 43.6% to 78.2%. We found significant stepwise increases in miR‐96 and miR‐183 expression with advancing tumor grade (miR‐96, P = 0.0057; and miR‐183, P = 0.0036) and pathological stage (miR‐96, P = 0.0332; and miR‐183, P = 0.0117). The expression levels of the microRNA were significantly lower in urine collected after surgery (miR‐96, P = 0.0241; and miR‐183, P = 0.0045). In conclusion, miR‐96 and miR‐183 in urine are promising tumor markers for UC. In particular, miR‐96 may be a good diagnostic marker in combination with urinary cytology. (Cancer Sci 2011; 102: 522–529)

Prognosis of Japanese Metastatic Renal Cell Carcinoma Patients in the Cytokine Era: A Cooperative Group Report of 1463 Patients

BACKGROUND Incidence rate of renal cell carcinoma (RCC) differs among countries. The rates of Asian countries are lower than those of countries in North America or Europe but are exceptionally high in Japanese males. Approximately 30% of patients with RCC have metastasis at initial diagnosis, and another 30% have metastasis after nephrectomy. Clinical studies of risk factors in patients with metastatic RCC (mRCC) are mainly based on data from non-Asian patients. OBJECTIVES We aimed to investigate the prognosis of Japanese patients and their prognostic factors. DESIGN, SETTING, AND PARTICIPANTS The subjects of this study were 1463 patients who were clinically diagnosed with RCC with metastasis in 40 Japanese hospitals between January 1988 and November 2002. MEASUREMENTS The primary end point was overall survival calculated from first diagnosis of mRCC to death or last follow-up. We also investigated the relationship between survival and clinical features. RESULTS AND LIMITATIONS The median overall survival time was 21.4 mo. The estimated survival rates at 1, 3, 5, and 10 yr were 64.2%, 35.2%, 22.5%, and 9.1%, respectively; they contrasted with data from the United States of 54%, 19%, 10%, and 6%, respectively for the same periods. A high percentage of patients had undergone nephrectomy (80.5%) and metastasectomy (20.8%), both of which were shown to prolong survival. CONCLUSIONS The median survival time in the present study was approximately twice as long as that of previous studies from North America or Europe. Early diagnosis of metastasis, nephrectomy, metastasectomy, and cytokine-based therapy seemed to improve the prognosis of RCC patients in the present study.

The functional significance of miR-1 and miR-133a in renal cell carcinoma

PURPOSE The aim of this study was to find a novel molecular network involved in renal cell carcinoma (RCC) development through investigating the functions of miR-1 and miR-133a and their target genes. METHODS We checked the expression levels of miR-1 and miR-133a in RCC cell lines and specimens (N=40) using real time RT-PCR. MiR-1 and miR-133a transfectants were subjected to a gain-of-function study to identify the functions of the miRNAs. To find the target genes of the miRNAs, we analysed the gene expression profile of their transfectants and performed a luciferase reporter assay. mRNA expression levels of the candidate target gene in the clinical specimens were examined, and loss-of-function studies were performed. RESULTS The expression levels of miR-1 and miR-133a were significantly suppressed in RCC cell lines and specimens. Ectopic restoration of miR-1 and miR-133a showed significant inhibition of cell proliferation and invasion, and moreover, revealed induction of apoptosis and cell cycle arrest. The luciferase assay revealed transgelin-2 (TAGLN2), selected as a target gene for miR-1 and miR-133a on the basis of the gene expression profile, to be directly regulated by both miR-1 and miR-133a. The loss-of-function studies showed significant inhibitions of cell proliferation and invasion in the si-TAGLN2 transfectant. The expression level of TAGLN2 mRNA was significantly up-regulated in the RCC specimens; in addition, there was a statistically significant inverse correlation between TAGLN2 and miR-1 and miR-133a expression. CONCLUSIONS Our data indicate that up-regulation of the oncogenic TAGLN2 was due to down-regulation of tumour-suppressive miR-1 and miR-133a in human RCC.

Correlation between thymidine phosphorylase expression and prognosis in human renal cell carcinoma.

PURPOSEThymidine phosphorylase (TP) is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and has angiogenic activity. We examined whether TP expression in renal cell carcinoma (RCC) is associated with microvessel density as a marker of angiogenesis, clinicopathologic characteristics, and outcome.PATIENTS AND METHODSThe enzymatic activity and expression of TP were examined in 18 RCCs and 19 kidney tissues not grossly involved with tumor from 24 patients with 13 paired samples and 11 unpaired samples by spectrophotometry and immunoblotting. The relationship between TP expression and microvessel density was assessed by immunohistochemistry in 133 RCCs.RESULTSThe median enzymatic activity of TP in RCCs was nine fold higher than that in nonneoplastic kidney tissues (P < .001). Similar results were obtained by immunoblot analysis. According to the TP staining profile, tumors were classified as no or low, intermediate, or high TP-expressing tumors. TP positivity was significantly correlated ...

miR-218 on the genomic loss region of chromosome 4p15.31 functions as a tumor suppressor in bladder cancer

Growing evidence suggests that microRNAs (miRNAs) are aberrantly expressed in many human cancers, and that they play significant roles in carcinogenesis and cancer progression. The identification of tumor suppressive miRNAs and their target genes could provide new insights into the mechanism of carcinogenesis. However, the genetic or epigenetic regulations of these miRNAs have not yet been fully elucidated in bladder cancer (BC). Chromosomal alterations of cancer cells give us important information for the identification of tumor suppressor genes. Our miRNA array-comparative genomic hybridization (CGH) analysis showed several miRNAs to be candidate tumor suppressors of BC. Our array-CGH analysis revealed that chromosome 4 was lost in all BC cell lines. We selected 19 miRNAs located on chromosome 4 and evaluated their expression levels in cancer cell lines as well as clinical samples. Gain-of-function analysis revealed that miR-218 inhibited BC cell proliferation, migration and invasion. Furthermore, flow cytometry analysis showed that it induced BC cell apoptosis. Genome-wide gene expression analysis showed that it targeted multiple oncogenes in BC. Our study is the first to demonstrate that miR-218 located on chrosomosme 4p15.31 is a tumor suppressive miRNA in BC. The identification of tumor suppressive miRNAs and their target genes on the basis of array-CGH analysis could provide new insights into the mechanisms of BC carcinogenesis.

MiR-133a induces apoptosis through direct regulation of GSTP1 in bladder cancer cell lines

OBJECTIVE We previously demonstrated that miR-133a is a tumor-suppressive microRNA (miRNA) and is commonly down-regulated in human bladder cancer (BC). The aim of this study is to determine a novel oncogenic gene targeted by miR-133a in BC. METHODS To identify genes targeted by miR-133a, an oligo-microarray analysis was performed using the miR-133a-transfected BC cell lines. For gain/loss-of-function studies, miR-133a/si-glutathione S-transferase π1 (GSTP1)-transfectants were subjected to XTT assay and flow cytometry to evaluate their cell viability and apoptosis status. The luciferase reporter assay was used to confirm the actual binding sites between miR-133a and GSTP1 mRNA. The mRNA and protein expression of GSTP1 in BC cell lines and clinical samples were evaluated by real-time RT-PCR and Western blot, respectively. RESULTS MiR-133a transfection induced cell viability inhibition and apoptosis in BC cell lines. We focused on the GSTP1 gene that was the top 7 down-regulated one in the gene profile from the miR-133a-transfectants. MiR-133a transfection repressed expression levels of mRNA and protein levels of GSTP1. A luciferase reporter assay suggested that the actual binding may occur between miR-133a and GSTP1 mRNA. Cell viability inhibition and apoptosis were induced in the si-GSTP1 transfectants compared with the controls (P < 0.005). GSTP1 mRNA expression levels in 43 clinical BCs were significantly higher than those in eight normal bladder epitheliums (P = 0.0277). CONCLUSION Our data suggest that tumor suppressive miR-133a directly regulated oncogenic GSTP1 gene in BC, and that an anti-apoptotic effect mediated by GSTP1 is maintained by miR-133a down-regulation in human BC.

Sphingosine induces apoptosis in androgen‐independent human prostatic carcinoma DU‐145 cells by suppression of bcl‐XL gene expression

Our recent studies have suggested that sphingosine, an endogenous protein kinase C (PKC) inhibitor, may mediate apoptosis induced by a phorbol ester (PMA) in human promyelocytic leukemia HL‐60 cells [Ohta et al. Cancer Res. 1995;55:691–697], and that the apoptotic induction by both PMA and sphingosine is accompanied by down‐regulation of bcl‐2, a gene which acts to prevent apoptotic cell death [Sakakura et al. FEBS Lett. 1996;397:177–180]. In this study, we examined the sphingosine‐induced apoptosis of the androgen‐independent human prostatic carcinoma cell line DU‐145, which expresses bcl‐XL and Bax but not bcl‐2, and found that treatment of DU‐145 cells with sphingosine suppressed bcl‐XL in both mRNA and protein levels but did not change bax expression at all. In contrast, in apoptotic cells treated with a PKC inhibitor, staurosporine, no effect on bcl‐XL or bax expression was observed. The initial metabolites of sphingosine in the cells, ceramide and sphingosine 1‐phosphate, failed to induce apoptosis. These results indicate that, in DU‐145 cells, sphingosine, but not its metabolites, induces apoptosis through down‐regulation of bcl‐XL, independently of PKC inhibition. Our present results, together with previous observations, strongly suggest that apoptosis regulatory genes differ according to cell type and apoptosis induction through sphingosine is accompanied by inhibition of either bcl‐2 or bcl‐XL activity in these cells.