Molecular Mechanism And Regulation Of SNF5 Gene Expression In Bladder Cancer

Background:Bladder cancer is characterized by a high drug-resistance,high recurrence,high heterogeneity and the mortality.Meantime,the evolution of Bladder cancer is a multi-stage and multi-genes process and Bladder cancer is the most common tumor among urogenital system in China with its increasing incidence and younger trend.Recent evidence suggest that abnormal genetic and epigenetic heredity is highly relevant to the development of Bladder cancer which challenges the prognosis and treatment of Bladder cancer.Growing evidence suggest that changes in epigenetic stability could affect gene expression(activate or silence some genes)and perturbs differentiation programmes and even cause cancer.The SWI/SNF complexes are a family of multi-subunit complexes that use the energy of adenosine triphosphate(ATP)hydrolysis to remodel nucleosomes and is a hot research area in epigenetics.The complex or the subunit are involved in a variety of cellular processes,including DNA repair,DNA methylation,activation or repression of transcription and cell cycle.As a key subunit of SWI/SNF complexes,the mutation and deficiency of SNF5 has been confirmed in a large number of tumors.Objectives:Based on the previous work,our research group found that SNF5 is abnormally expressed in Bladder cancer tissues.Therefore,we propose that SNF5 may also play a critical role in the development of Bladder cancer.However,mechanisms by which disturbation of the SWI/SNF complexes promote oncogenesis are not fully elucidated;Here,we focused the mechanism of SNF5 in Bladder cancer from the following aspects: non-coding RNA and transcriptional regulation.Methods and Results:1.Non-coding RNA(1)SNF5: miR-206 new targetBased on bioinformatics predictions,using the luciferase report system、miR-206 mutant、miR-206 mimic and miR-206 inhibitor,we confirmed SNF5 is a new target of miR-206.(2)Using Real-time and immunohistochemical method to detect mRNA or protein levels of SNF5,miR-206 among bladder cancer tissues.Our results showed that miR-206 is low expressed in bladder cancer tissues,while the m RNA or protein level of SNF5 are overexpressed(28/38).The expression level of SNF5 and miR-206 is negatively correlated.However,SNF5 is not relevant to pathological grade analysis.2.Transcriptional regulation(1)We found the potential binding site between the 5 ’regulatory region of SNF5 and the transcription factor HSF1 via bioinformatics prediction.Next,we found that HSF1 may bind to the 5’ flanking region of SNF5 via the website http://www.cbrc.jp/research/db/ TFSEARCH.html.We chose the bladder cancer cell line 5637 and transiently overexpressed HSF1.Western blot analysis showed that HSF1 could enhance SNF5 expression apparently.In vivo CHIP analysis found that HSF1 could bind to the promoter region(-2304-2696)of SNF5.All the above results confirmed that HSF1 may regulate SNF5 expression on transcriptional level.(2)Using Real-time and immunohistochemical method to detect mRNA or protein levels of SNF5 and HSF1 among bladder cancer tissues.Our results showed that SNF5 and HSF1 are both overexpressed in bladder cancer tissues.Also,the two expression level is positively relevant.ConclusionWe explored the regulation of SNF5 gene expression in Bladder cancer from the following aspects: non-coding RNA and transcriptional regulation.Our results showed that SNF5 is a new target of miR-206 and HSF1 is a critical transcription factor of SNF5.Also,we detect the m RNA and protein expression level of miR-206、 HSF1、SNF5 in bladder cancer tissues.Our research firstly revealed that miR-206 negetively regulate SNF5 while HSF1 positively regulate SNF5 expression on transcriptional level in bladder cancer.Further investigations on SNF5 will provide greater insight on the prognosis and treatment of Bladder cancer.