Phosphosulindac, miRNAs and cancer racial disparity

描述(由申请人提供)：流行病学数据表明，在高加索人和非裔美国人(AA)之间，结肠癌的发病率和死亡率不成比例。尽管社会经济和饮食差异是造成这种差异的原因，但也必须涉及其他潜在因素。例如，对化学预防药物的反应在这两个人群中是不同的。由于化学预防药物通过分子靶标发挥作用，这种差异表明基因水平上的差异。因此，解决耐药问题的化学预防药物的产生和评估是至关重要的。一种很有前途的结肠癌化学预防药物--磷酸舒林酸(P-S)，通过抑制细胞增殖和增强细胞杀伤作用，比舒林酸更有效地抑制结肠癌细胞的生长。然而，人们对癌细胞中导致这种效应的分子靶点知之甚少。根据初步结果，我们的假设是，再生障碍性贫血和高加索人之间miRNA的表达/调控不同，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)结直肠癌发病率的不同。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对高加索人和再生障碍性结肠癌来源的人结肠癌细胞系中P53、核因子-kB、2-连环蛋白和细胞动力学的影响；2)评估P-S对p53基因缺失的结肠癌小鼠模型中miRNA谱的影响；以及3)测定再生障碍性结肠癌和高加索人结肠癌标本中的miRNA谱。这些发现的结果将导致对一个世界性问题的理解，并为将覆盖不同人群的化学预防药物的开发提供细节。 公共卫生相关性：我们将确定P-S发挥抑制结肠癌细胞生长作用的机制，并解决由于基因突变造成的种族差异。我们将在细胞培养中，使用来自高加索人和AA结肠癌组织的细胞系，评估(通过微阵列分析)转录因子和miRNAs表达的变化。此外，我们将测试我们的体外研究结果是否与结肠癌的临床前模型相关。本研究将在P53基因缺失和C57BL/6(亲本背景)小鼠模型上直接评价P-S对转录因子和miRNAs表达的影响。因此，我们将检验体外研究的关键机制发现。最后，我们将在蛋白质、RNA和DNA水平上比较和对比高加索人和再障患者的前瞻性和回溯性结肠癌组织。若能证明P-S可诱导恶性结肠癌细胞内潜在的重要分子变化，可能与其在癌症中的药理作用有关，将预示着在预防结肠癌方面的重大突破。此外，能够将基因原因归因于对化疗药物的抗药性，将解决种族差异的问题。

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.