TRIO Amplification and Abundant mRNA Expression Is Associated with Invasive Tumor Growth and Rapid Tumor Cell Proliferation in Urinary Bladder Cancer

Abstract

Studies by comparative genome hybridization have suggested that 5p amplification is related to tumor progression in urinary bladder cancer. In this study seven genes (TAS2R, ADCY2, DNAH5, CTNND2, TRIO, ANKH, and MYO10) located to 5p15.31-5p15.1 were analyzed by fluorescence in situ hybridization using a tissue microarray containing samples from tumors and cell lines with known 5p amplification by comparative genome hybridization. Amplification frequency was highest for TRIO, which maps to 5p15.2 and encodes a protein with a putative role in cellcycle regulation. To further investigate the role of TRIO amplification in bladder cancer, a tissue microarray containing samples from 2317 bladder tumors was used for fluorescence in situ hybridization analysis. TRIO amplification was strongly associated with invasive tumor phenotype, high tumor grade, and rapid tumor cell proliferation (Ki67 LI) (P < 0.0001 each). Only 7 of 456 pTaG1/G2 tumors (1.5%) but 62 of 485 pT1-4 carcinomas (12.8%) had TRIO amplification. TRIO amplification was not associated with poor prognosis. Using a frozen bladder tumor tissue microarray RNA in situ hybridization confirmed that TRIO is up-regulated in amplified tumors. It is concluded that TRIO up-regulation through amplification has a potential role in bladder cancer progression. Studies by comparative genomic hybridization (CGH) demonstrated gains and amplifications at many different chromosomal loci mainly in invasive bladder cancer. 1 Gene copy number increase is an important mechanism leading to abnormal expression of known oncogenes such as MYC at 8q24, CCND1 at 11q13, or HER2 at 17q21. 2-4 However, most of the chromosomal regions found amplified in bladder cancer 1 do not contain known oncogenes, suggesting that many amplification target genes remain to be identified.Amplifications of the short arm of chromosome 5 are of particular interest. In previous CGH studies 5p amplification was found to be one of the few alterations occurring more frequently in muscle invasive tumors (stage pT2 and higher) than in early invasive cancers (stage pT1). 5 Our hypothesis of a role of 5p amplification for bladder cancer progression was further corroborated by the results of a second CGH study finding a significant association between 5p amplifications and an increased risk for tumor progression in a series of pT1 carcinomas. 6 Because amplifications often cover large areas of 5p in bladder cancer, it is difficult to narrow down the region of amplification using positional cloning approaches. Based on our CGH studies, one of the most common sites of amplification is in the 5p15-p14 region. 5 In an attempt to find oncogene candidates among known genes allocated in this chromosomal area, we became interested in TRIO located at 5p15.2. 7 The TRIO protein contains a serine/threonine kinase domain and two guanine nucleotide exchange factor domains for the family of Rho-like GTPases, specific for Rac1 and RhoA. 8 These functional domains suggest that this enzyme may play a role in signaling pathways contro...

Gain of 5p15.33 Is Associated with Progression of Bladder Cancer

“…FISH analysis confirmed that gain of 5p15.33 was not only associated with high histological grade but also advanced pathological stage. These observations are comparable with published data on bladder cancer obtained by conventional and array CGH analyses [3, 5, 9, 23]. In this study, we analyzed copy number gains, but not copy number loss.…”

Multiple Microalterations Detected at High Frequency in Oral Cancer

“…TRIO contains three functional domains-a serine/threonine kinase domain and two guanine exchange factor domains. TRIO amplification and abundant expression was recently reported in lung carcinoma and bladder cancer (17)(18)(19). Although 5p amplifications have been well -documented in oral cancer, this is the first report of the microamplification of the TRIO locus in oral cancer, probably due to insufficient resolution of both conventional techniques and interval marker array CGH.…”

Consistent genomic alterations in carcinoma in situ of the urinary bladder confirm the presence of two major pathways in bladder cancer development

“…Located in this region, TRIO has previously been demonstrated to be amplified and overexpressed in bladder cancer and this was associated with the invasive phenotype, high grade and rapid proliferation, but not with progression. 41 We could not confirm overexpression of TRIO in our geneexpression microarray material. Although 5p-gains were associated with CIS, it was never the only chromosomal change in any sample.…”