We investigated expression profiles of microRNA (miRNA) in renal cell carcinoma [clear cell carcinomas (CCC) and chromophobe renal cell carcinomas (ChCC)] and in normal kidneys by using a miRNA microarray platform which covers a total of 470 human miRNAs (Sanger miRBase release 9.1). Unsupervised hierarchical cluster analysis revealed that CCC and ChCC were separable and that no subgroups were identified in CCCs. We found that 43 miRNAs were differentially expressed between CCC and normal kidney, of which 37 were significantly down-regulated in CCC and the other 6 were up-regulated. We also found that 57 miRNAs were differentially expressed between ChCC and normal kidney, of which 51 were significantly down-regulated in ChCC and the other 6 were up-regulated. Together, these observations indicate that expression of miRNAs tends to be down-regulated in both CCC and ChCC compared with normal kidney. We observed that miR-141 and miR-200c were the most significantly down-regulated miRNAs in CCCs. Indeed, in all cases of CCC analysed, both miR-141 and miR-200c were down-regulated in comparison with normal kidney. Microarray data and quantitative RT-PCR showed that these two miRNAs were expressed concordantly. TargetScan algorithm revealed that ZFHX1B mRNA is a hypothetical target of both miR-141 and -200c. We established by quantitative RT-PCR that, in CCCs in which miR-141 and miR-200c were down-regulated, ZFHX1B, a transcriptional repressor for CDH1/E-cadherin, tended to be up-regulated. Furthermore, we found that overexpression of miR-141 and miR-200c caused down-regulation of ZFHX1B and up-regulation of E-cadherin in two renal carcinoma cell lines, ACHN and 786-O. On the basis of these findings, we suggest that down-regulation of miR-141 and miR-200c in CCCs might be involved in suppression of CDH1/E-cadherin transcription via up-regulation of ZFHX1B.

We analysed chromosomal copy number aberrations (CNAs) in renal cell carcinomas by array-based comparative genomic hybridization, using a genome-wide scanning array with 2304 BAC and PAC clones covering the whole human genome at a resolution of roughly 1.3 Mb. A total of 30 samples of renal cell carcinoma were analysed, including 26 cases of clear cell carcinoma (CCC) and four cases of chromophobe renal cell carcinoma (ChCC). In CCCs, gains of chromosomes 5q33.1-qter (58%), 7q11.22-q35 (35%) and 16p12.3-p13.12 (19%), and losses of chromosomes 3p25.1-p25.3 (77%), 3p21.31-p22.3 (81%), 3p14.1-p14.2 (77%), 8p23.3 (31%), 9q21.13-qter (19%) and 14q32.32-qter (38%) were detected. On the other hand, the patterns of CNAs differed markedly between CCCs and ChCCs. Next, we examined the correlation of CNAs with expression profiles in the same tumour samples in 22/26 cases of CCC, using oligonucleotide microarray. We extracted genes that were differentially expressed between cases with and without CNAs, and found that significantly more up-regulated genes were localized on chromosomes 5 and 7, where recurrent genomic gains have been detected. Conversely, significantly more down-regulated genes were localized on chromosomes 14 and 3, where recurrent genomic losses have been detected. These results revealed that CNAs were correlated with deregulation of gene expression in CCCs. Furthermore, we compared the patterns of genomic imbalance with histopathological features, and found that loss of 14q appeared to be a specific and additional genetic abnormality in high-grade CCC. When we compared the expression profiles of low-grade CCCs with those of high-grade CCCs, differentially down-regulated genes tended to be localized on chromosomes 14 and 9. Thus, it is suggested that copy number loss at 14q in high-grade CCC may be involved in the down-regulation of genes located in this region.

Rearranged during transfection (RET) fusions have been newly identified in approximately 1% of patients with primary lung tumors. However, patient-derived lung cancer cell lines harboring RET fusions have not yet been established or identified, and therefore, the effectiveness of an RET inhibitor on lung tumors with endogenous RET fusion has not yet been studied. In this study, we report identification of CCDC6-RET fusion in the human lung adenocarcinoma cell line LC-2/ad. LC-2/ad showed distinctive sensitivity to the RET inhibitor, vandetanib, among 39 non-small lung cancer cell lines. The xenograft tumor of LC-2/ad showed cribriform acinar structures, a morphologic feature of primary RET fusion-positive lung adenocarcinomas. LC-2/ad cells could provide useful resources to analyze molecular functions of RET-fusion protein and its response to RET inhibitors.

BackgroundClinical outcome of patients with high-grade ccRCC (clear cell renal cell carcinoma) remains still poor despite recent advances in treatment strategies. Molecular mechanism of pathogenesis in developing high-grade ccRCC must be clarified. In the present study, we found that SAV1 was significantly downregulated with copy number loss in high-grade ccRCCs. Therefore, we investigated the SAV1 function on cell proliferation and apoptosis in vitro. Furthermore, we attempted to clarify the downstream signaling which is regulated by SAV1.MethodsWe performed array CGH and gene expression analysis of 8 RCC cell lines (786-O, 769-P, KMRC-1, KMRC-2, KMRC-3, KMRC-20, TUHR4TKB, and Caki-2), and expression level of mRNA was confirmed by quantitative RT-PCR (qRT-PCR) analysis. We next re-expressed SAV1 in 786-O cells, and analyzed its colony-forming activity. Then, we transfected siRNAs of SAV1 into the kidney epithelial cell line HK2 and renal proximal tubule epithelial cells (RPTECs), and analyzed their proliferation and apoptosis. Furthermore, the activity of YAP1, which is a downstream molecule of SAV1, was evaluated by western blot analysis, reporter assay and immunohistochemical analysis.ResultsWe found that SAV1, a component of the Hippo pathway, is frequently downregulated in high-grade ccRCC. SAV1 is located on chromosome 14q22.1, where copy number loss had been observed in 7 of 12 high-grade ccRCCs in our previous study, suggesting that gene copy number loss is responsible for the downregulation of SAV1. Colony-forming activity by 786-O cells, which show homozygous loss of SAV1, was significantly reduced when SAV1 was re-introduced exogenously. Knockdown of SAV1 promoted proliferation of HK2 and RPTEC. Although the phosphorylation level of YAP1 was low in 786-O cells, it was elevated in SAV1-transduced 786-O cells. Furthermore, the transcriptional activity of the YAP1 and TEAD3 complex was inhibited in SAV1-transduced 786-O cells. Immunohistochemistry frequently demonstrated nuclear localization of YAP1 in ccRCC cases with SAV1 downregulation, and it was preferentially detected in high-grade ccRCC.ConclusionsTaken together, downregulation of SAV1 and the consequent YAP1 activation are involved in the pathogenesis of high-grade ccRCC. It is an attractive hypothesis that Hippo signaling could be candidates for new therapeutic target.