KISS1 is a metastasis suppressor gene that is lost in several malignancies, including bladder cancer. We tested the epigenetic silencing hypothesis and evaluated the biological influence of KISS1 methylation on its expression and clinical relevance in bladder cancer. KISS1 hypermethylation was frequent in bladder cancer cells analyzed by methylation-specific PCR and bisulfite sequencing and was associated with low gene expression, being restored in vitro by demethylating azacytidine. Hypermethylation was also frequently observed in a large series of bladder tumors (83.1%, n ؍ 804). KISS1 methylation was associated with increasing stage (P ؍ 0.001) and tumor grade (P ؍ 0.010). KISS1 methylation was associated with low KISS1 transcript expression by quantitative RT-PCR (P ؍ 0.037). KISS1 transcript expression was also associated with histopathological tumor stage (P < 0.0005). Low transcript expression alone (P ؍ 0.003) or combined with methylation (P ؍ 0.019) was associated with poor disease-specific survival (n ؍ 205).KISS1 transcript expression remained an independent prognosticator in multivariate analyses (P ؍ 0.017). KISS1 hypermethylation was identified in bladder cancer, providing a potential mechanistic explanation (epigenetic silencing) for the observed loss of KISS1 in uroepithelial malignancies. Associations of KISS1 methylation and its expression with histopathological variables and poor survival suggest the utility of incorporating KISS1 measurement using paraffin-embedded material for tumor stratification and clinical outcome prognosis of patients with uroepithelial neoplasias.
Changes in DNA methylation of tumor suppressors can occur early in carcinogenesis and are potentially important early indicators of cancer. The objective of this study was to assess the methylation of 25 tumor suppressor genes in bladder cancer using a methylation-specific (MS) multiplex ligation-dependent probe amplification assay (MLPA). Initial analyses in bladder cancer cell lines (n ؍ 14) and fresh-frozen primary bladder tumor specimens (n ؍ 31) supported the panel of genes selected being altered in bladder cancer. The process of MS-MLPA was optimized for its application in body fluids using two independent training and validation sets of urinary specimens (n ؍ 146), including patients with bladder cancer (n ؍ 96) and controls (n ؍ 50). BRCA1 (71.0%), WT1 (38.7%), and RARB (38.7%) were the most frequently methylated genes in bladder tumors, with WT1 methylation being significantly associated with tumor stage (P ؍ 0.011). WT1 and PAX5A were identified as methylated tumor suppressors. In addition, BRCA1, WT1, and RARB were the most frequently methylated genes in urinary specimens. Receiver operating characteristic curve analyses revealed significant diagnostic accuracies in both urinary sets for BRCA1, RARB, and WT1.
Myopodin is an actin-binding protein that shuttles between the nucleus and the cytoplasm. After identifying an enriched CpG island encompassing the transcription site of myopodin, we aimed at evaluating the potential relevance of myopodin methylation in bladder cancer. The epigenetic silencing of myopodin by hypermethylation was tested in bladder cancer cells (n=12) before and after azacytidine treatment. Myopodin hypermethylation was associated with gene expression, being increased in vitro by this demethylating agent. The methylation status of myopodin promoter was then evaluated by methylation-specific polymerase chain reaction (MS-PCR) analyses. Myopodin was revealed to be frequently methylated in a large series of 466 bladder tumours (68.7%). Myopodin methylation was significantly associated with tumour stage (p<0.0005) and tumour grade (p=0.037). Myopodin expression patterns were analysed by immunohistochemistry on tissue arrays containing bladder tumours for which myopodin methylation was assessed (n=177). The presence of low nuclear myopodin expression alone (p = 0.031) or combined with myopodin methylation (p=0.008) was associated with poor survival. Moreover, myopodin methylation in 164 urinary specimens distinguished patients with bladder cancer from controls with a sensitivity of 65.0%, a specificity of 79.8%, and a global accuracy of 75.3%. Thus, myopodin was identified to be epigenetically modified in bladder cancer. The association of myopodin methylation and nuclear expression patterns with cancer progression and clinical outcome, together with its ability to detect bladder cancer patients using urinary specimens, suggests the utility of incorporating myopodin methylation assessment in the clinical management of patients affected by uroepithelial neoplasias.
Tumor suppressor gene methylation allowed for histopathological and clinical stratification. Urine methylation has noninvasive usefulness not only for diagnostic assessment but also as independent bladder cancer prognosticators.
PMF1 was identified to be epigenetically modified in bladder cancer. The association of PMF1 methylation with tumor progression and its diagnostic ability using urinary specimens support including PMF1 assessment for the clinical management of bladder cancer patients.
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