Androgen receptor (AR) signals have been implicated in bladder carcinogenesis and tumor progression. Activation of Wnt/b-catenin signaling has also been reported to correlate with bladder cancer progression and poor patients' outcomes. However, cross talk between AR and b-catenin pathways in bladder cancer remains uncharacterized. In radical cystectomy specimens, we immunohistochemically confirmed aberrant expression of b-catenin especially in aggressive tumors. There was a strong association between nuclear expressions of AR and b-catenin in bladder tumors (PZ0.0215). Kaplan-Meier and log-rank tests further revealed that reduced membranous b-catenin expression (PZ0.0276), nuclear b-catenin expression (PZ0.0802), and co-expression of nuclear AR and b-catenin (PZ0.0043) correlated with tumor progression after cystectomy. We then assessed the effects of androgen on b-catenin in AR-positive and AR-negative bladder cancer cell lines. A synthetic androgen R1881 increased the expression of an active form of b-catenin and its downstream target c-myc only in AR-positive lines. R1881 also enhanced the activity of b-catenin-mediated transcription, which was abolished by an AR antagonist hydroxyflutamide. Using western blotting and immunofluorescence, R1881 was found to induce nuclear translocation of b-catenin when co-localized with AR. Finally, co-immunoprecipitation revealed androgeninduced associations of AR with b-catenin or T-cell factor (TCF) in bladder cancer cells. Thus, it was likely that androgen was able to activate b-catenin signaling through the AR pathway in bladder cancer cells. Our results also suggest that activation of b-catenin signaling possibly via formation of AR/b-catenin/TCF complex contributes to the progression of bladder cancer, which may enhance the feasibility of androgen deprivation as a potential therapeutic approach.

Sumoylation is a posttranslational modification that regulates a wide spectrum of cellular activities. Cardiomyopathy is the leading cause of heart failure. Whether sumoylation, particularly SUMO-2/3 conjugation, is involved in cardiomyopathy has not been investigated. We report here that SUMO-2/3 conjugation was elevated in the human failing hearts, and we investigated the impact of increased SUMO-2 conjugation on heart function by using the gain-of-function approach in mice, in which cardiac specific expression of constitutively active SUMO-2 was governed by alpha myosin heavy chain promoter (MHC-SUMO-2 transgenic, SUMO-2-Tg). Four of five independent SUMO-2-Tg mouse lines exhibited cardiomyopathy with various severities, ranging from acute heart failure leading to early death to the development of chronic cardiomyopathy with aging. We further revealed that SUMO-2 directly regulated apoptotic process by at least partially targeting calpain 2 and its natural inhibitor calpastatin. SUMO conjugation to calpain 2 promoted its enzymatic activity, and SUMO attachment to calpastatin mainly promoted its turnover and altered its subcellular distribution. Thus, enhanced SUMO-2 conjugation led to increased apoptosis and played a pathogenic role in the development of cardiomyopathy and heart failure.

Background How canonical Wnt/β-catenin signals in adult hearts, especially in different diseased states, remains unclear. The proto-oncogene, c-Myc, is a Wnt target and an early response gene during cardiac stress. It is not clear if c-Myc is activated or how it is regulated during heart failure. Methods and Results We investigated canonical Wnt/β-catenin signaling and how it regulated c-Myc expression in failing hearts of human ischemic heart disease (IHD), idiopathic dilated cardiomyopathy (IDC), and murine desmin-related cardiomyopathy (DES). Our data demonstrated that canonical Wnt/β-catenin signaling was activated through nuclear accumulation of β-catenin in IDC, IHD and DES when compared to non-failing controls and Transcription Factor 7-like 2 (TCF7L2) was the main β-catenin partner of the T-cell factor (TCF) family in adult hearts. We further revealed that c-Myc mRNA and protein levels were significantly elevated in failing hearts by real-time RT-PCR, Western blotting, and immunohistochemical staining. Immunoprecipitation and confocal microscopy further showed that β-catenin interacted and co-localized with TCF7L2. More importantly, chromatin immunoprecipitation confirmed that β-catenin and TCF7L2 were recruited to the regulatory elements of c-Myc. This recruitment was associated with increased histone H3 acetylation and transcriptional upregulation of c-Myc. With lentiviral infection, TCF7L2 overexpression increased c-Myc expression and cardiomyocyte size while shRNA mediated knockdown of TCF7L2 suppressed c-Myc expression and cardiomyocyte growth in cultured neonatal rat cardiomyocytes. Conclusions This study indicates that TCF7L2 mediates canonic Wnt/β-catenin signaling and c-Myc upregulation during abnormal cardiac remodeling in heart failure and suppression of Wnt/β-catenin to c-Myc axis can be explored for preventing and treating heart failure.