Bladder cancer is the fifth most common cancer in the United States. Although these tumors can be removed by transurethral resection, about 50-80% will recur. Since recurrence is a common feature of superficial bladder cancer, it is often thought that this may be due to pre malignant changes in the bladder, although it has not been well defined molecularly. Aberrant DNA methylation has been proposed as an attractive candidate for the underlying alterations governing pre malignant changes. Hypomethylation of LINE-1 retrotransposable elements is quite common in many cancers including bladder cancer. We recently found hypomethylation of a specific LINE-1 element in bladder cancer cells that was also present in the corresponding normal appearing cells regardless of the distance from the site of the tumor. This particular LINE-1 element (MET-LINE) is located in the intronic region of the proto- oncogene MET and we have detected the expression of a truncated form of the oncogene in cells with hypomethylated promoter of MET-LINE. These results may indicate pre malignant changes in the bladder where there is a reduction of methylation of a specific LINE 1 and an increased likelihood of expression of an oncogene. In this proposal, we plan first to further investigate the correlation between hypomethylation of the specific LINE-1 and ectopic expression of truncated MET as one of mediators of pre milignant changes by the Pyrosequencing assay and real time RT-PCR to measure DNA methylation and gene expression;second to detect methylation changes of the MET-LINE in urine sediments of patients before and after surgical excision to study the potential role of hypomethylation of the MET-LINE as a marker of recurrence by a highly sensitive assay (MethyLight);and finally, to characterize the role of truncated MET during tumorigenesis. Accomplishment of these specific aims will allow us to obtain evidence of premalignant changes at the molecular level in bladder epithelial cells from bladder cancer patients without evidence of malignancy and address the potential mechanism of highly recurrent bladder cancers. Finally this translational project will bring together basic scientists and clinicians to translate clinical findings into laboratory questions and use these fundamental discoveries to better the lives of patients with this disease.
In the United States, bladder cancer is the fourth most common cancer diagnosis in men and the eighth most common in women with 50-80% of cases recurring, in 2007 there were 67160 new cases and 13750 deaths according to the Natinal Cancer Institute. Accomplishment of this proposal will allow us to elucidate the potential cause of the frequent recurrence of bladder cancer and develop a highly specific and sensitive biomarker not only for diagnosis of bladder cancer but also for monitoring the recurrence of bladder cancer.
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