Epigentic Alterations in Pre-malignant Tissue of the Bladder

描述(申请人提供)：膀胱癌是美国第五大常见癌症。虽然这些肿瘤可以通过经尿道电切切除，但大约50%-80%会复发。由于复发是浅表性膀胱癌的常见特征，人们通常认为这可能是由于膀胱癌前病变，尽管它在分子上还没有很好的定义。异常的DNA甲基化被认为是控制癌前病变的潜在改变的一个有吸引力的候选基因。LINE-1逆转录转座子的低甲基化在包括膀胱癌在内的许多癌症中相当常见。我们最近在膀胱癌细胞中发现了一个特定的Line-1元件的低甲基化，该元件也存在于相应的正常外观细胞中，而与肿瘤部位的距离无关。这个特殊的LINE-1元件(MET-LINE)位于原癌基因MET的内含子区域，我们已经在MET-LINE低甲基化启动子的细胞中检测到该癌基因的截短形式的表达。这些结果可能提示膀胱癌前病变，其中有一个特定的行1甲基化减少，并增加了癌基因表达的可能性。在这项建议中，我们计划首先通过焦磷酸测序和实时荧光RT-PCR来进一步研究特定LINE-1的低甲基化与截短MET异位表达之间的相关性，以此作为癌前病变的介质之一，以测量DNA甲基化和基因表达；其次检测手术切除前后患者尿沉渣中MET行的甲基化变化，以研究MET行低甲基化作为复发标志的潜在作用(甲基化检测)；最后，确定截短MET在肿瘤发生中的作用。这些特定目标的实现将使我们能够从分子水平上获得膀胱癌患者膀胱癌前病变的证据，并解决高复发率膀胱癌的潜在机制。最后，这个翻译项目将把基础科学家和临床医生聚集在一起，将临床发现转化为实验室问题，并利用这些基本发现来改善这种疾病患者的生活。公共卫生相关性：在美国，膀胱癌是男性第四大常见癌症诊断和女性第八大常见癌症诊断，有50%-80%的病例复发，根据国民癌症研究所的数据，2007年新增病例67160例，死亡13750例。这一建议的完成将使我们能够阐明膀胱癌频繁复发的潜在原因，并开发出一种高度特异和敏感的生物标志物，不仅可以用于膀胱癌的诊断，还可以用于监测膀胱癌的复发。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: 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.