Identification of prefoldin amplification (1q23.3-q24.1) in bladder cancer using comparative genomic hybridization (CGH) arrays of urinary DNA

Abstract

BackgroundArray-CGH represents a comprehensive tool to discover genomic disease alterations that could potentially be applied to body fluids. In this report, we aimed at applying array-CGH to urinary samples to characterize bladder cancer.MethodsUrinary DNA from bladder cancer patients and controls were hybridized on 44K oligonucleotide arrays. Validation analyses of identified regions and candidates included fluorescent in situ hybridization (FISH) and immunohistochemistry in an independent set of bladder tumors spotted on custom-made tissue arrays (n = 181).ResultsQuality control of array-CGH provided high reproducibility in dilution experiments and when comparing reference pools. The most frequent genomic alterations (minimal recurrent regions) among bladder cancer urinary specimens included gains at 1q and 5p, and losses at 10p and 11p. Supervised hierarchical clustering identified the gain at 1q23.3-q24.1 significantly correlated to stage (p = 0.011), and grade (p = 0.002). The amplification and overexpression of Prefoldin (PFND2), a selected candidate mapping to 1q23.3-q24.1, correlated to increasing stage and tumor grade by means of custom-designed and optimized FISH (p = 0.013 and p = 0.023, respectively), and immunohistochemistry (p ≤0.0005 and p = 0.011, respectively), in an independent set of bladder tumors included in tissue arrays. Moreover, PFND2 overexpression was significantly associated with poor disease-specific survival (p ≤0.0005). PFND2 was amplified and overexpressed in bladder tumors belonging to patients providing urinary specimens where 1q23.3q24.1 amplification was detected by array-CGH.ConclusionsGenomic profiles of urinary DNA mirrowed bladder tumors. Molecular profiling of urinary DNA using array-CGH contributed to further characterize genomic alterations involved in bladder cancer progression. PFND2 was identified as a tumor stratification and clinical outcome prognostic biomarker for bladder cancer patients.

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“…Prefoldins (PFDs) [33] are hetero-oligomer chaperones involved in cancer development, since their main targets are actin and tubulin [33]. Up-regulation of members of the PFD protein family has been reported in different tumours, such as glioblastoma [34], breast [35], pancreatic [36], colon [37], bladder [38] and cervical [39] carcinomas. The heat shock proteins (HSPs) [40] have been reported to be significantly elevated in many kind of human cancers and their over-expression has been correlated to therapeutic resistance and poor survival.…”

Integrative Analysis of 1q23.3 Copy-Number Gain in Metastatic Urothelial Carcinoma

“…PFDN2 is a nuclear chaperone protein that forms a subunit of the prefoldin complex, which stabilizes newly synthesized peptides to facilitate appropriate protein folding, and may be critically important for tubulin folding (36). Another study (37) reported that PFND2 overexpression was strongly associated with disease-specific survival in a cohort of 181 high-grade bladder cancer patients with mixed pathological stages. F11R , otherwise known as Junctional Adhesion Molecule A (JAM-A), is involved in the regulation of tight junction development between epithelial cells.…”

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“…PFD2 is a subunit of the prefoldin complex, localized in the cytoplasm and also into the nucleus and crucial for the folding of actin and tubulin [160]. Its overexpression has been associated with poor prognosis in the bladder carcinoma [161]. Interestingly, this protein is expressed at high levels in the tumor tissues and absent in the non-tumorals.…”