Phosphosulindac, miRNAs and cancer racial disparity

描述（由申请人提供）：流行病学数据表明，白种人和非裔美国人（AA）的结肠癌发病率和死亡率不成比例。虽然社会经济和饮食的差异导致了这种差异，但其他潜在因素也必须参与其中。例如，这两个人群对化学预防剂的反应是不同的。由于化学预防药物通过分子靶标发挥作用，这种差异可能表明遗传水平上的差异。因此，产生和评估化学预防剂，解决化学耐药性的问题是必不可少的。phospho-sulindac （P-S）是一种很有前景的结肠癌化学预防药物，通过抑制细胞增殖和增强细胞杀伤，比sulindac更有效地抑制结肠癌细胞的生长。然而，我们对癌细胞中导致这种效应的分子靶点知之甚少。基于初步结果，我们的假设是，miRNA表达/调控在AA和高加索人之间存在差异，这种差异可能至少部分解释了a)对化学预防的不同反应和b)结直肠癌的不同发病率。为了验证这些假设，我们提出了以下三个具体目标：1)研究P-S对源自高加索人和AA人结肠癌细胞系中p53、NF-kB、2-catenin和细胞动力学的影响；2)评估P- S对p53缺失小鼠结肠癌模型miRNA谱的影响；3)测定AA和高加索人结肠癌样本的miRNA谱。这些发现的结果将导致对一个世界性问题的理解，并为开发跨越不同人群的化学预防剂提供细节。

DESCRIPTION (provided by applicant): Epidemiological data has demonstrated that colon cancer is disproportional in incidence and mortality between Caucasians and African Americans (AA). Whereas socioeconomic and dietary differences contribute to this disparity other underlying factors must be involved. For instance, the response to chemopreventive agents is different between these two populations. Since chemopreventive agents exert their effect through a molecular target, this disparity would suggest differences at the genetic level. Therefore, the generation and evaluation of chemopreventive agents that address the issue of chemo-resistance is essential. A promising colon cancer chemopreventive agent, phospho-sulindac (P-S), inhibits colon cancer cell growth more potently than sulindac by inhibiting cell proliferation and enhancing cell killing. However, very little is known about the molecular targets in the cancer cell that are responsible for this effect. Our hypothesis, based on preliminary results, is that miRNA expression/regulation differs between AA and Caucasians and this difference may account, at least in part, a) for the differential response to chemoprevention and b) for the differential incidence of colorectal cancer. To test these hypotheses, we propose the following three specific aims: 1) To study the effect of P-S on p53, NF-kB, 2-catenin, and cell kinetics in human colon cancer cell lines originating from Caucasians and AA; 2) To assess the effect of P- S on the miRNA profile in a p53 null murine model of colon cancer; and, 3) Determine the miRNA profile in human colon cancer samples from AA and Caucasian patients. The results from these findings will lead to the understanding of a worldwide issue and provide details for the development of chemopreventive agents that will span diverse populations. PUBLIC HEALTH RELEVANCE: We will define the mechanisms by which P-S exert its inhibitory effect on the growth of colon cancer cells and address racial disparities as a result of genetic mutations. We will evaluate in cell culture, using cell lines derived from Caucasians and AA colon cancer tissues, changes (by microarray analysis) in the expression of transcription factors and miRNAs. In addition, we will test whether our in vitro findings are relevant to a preclinical model of colon cancer. This study will evaluate directly in a p53 null and C57BL/6 (parent background) mice model the effect of P-S on the expressions of transcription factors and miRNAs. Thereby, we will test the key mechanistic findings from the in vitro study. Lastly, we will compare and contrast prospective and retrospective colon cancer tissue of Caucasians and AA at the protein, RNA, and DNA levels. Being able to demonstrate that P-S induces a potentially important molecular change in the malignant colonocytes that may be relevant to its pharmacological actions in cancer would indicate an important breakthrough in the prevention of colon cancer. Also, being able to attribute a genetic causative effect to resistance to chemotherapeutic agents will address the issue of racial disparity.