MicroRNA and colorectal cancer chemoprevention

According to the latest report of cancer statistics by American Cancer Society, colorectal cancer remains a leading cause of death from cancer in the United States. Therefore, there is still an unmet need to develop safer and more efficacious agents for treatment and prevention of colorectal cancer. Numerous studies report that the nonsteroidal anti-inflammatory drug (NSAID), sulindac is highly effective for the treatment of precancerous adenomas in individuals with familial adenomatous polyposis and shows promising anticancer activity in preclinical animal models; however, the adverse side effects resulting from cyclooxygenase (COX) inhibition limit the long-term use of sulindac for chemoprevention. Our previous studies reported that two non- COX inhibitory derivatives, sulindac sulfide amide (SSA) and sulindac benzylamine (SBA), can inhibit colorectal tumor cell growth with better potency and improved efficacy when compared to sulindac sulfide (SS).These results imply that anticancer activity of sulindac might attribute to other underlying mechanisms distinct from COX inhibition. In this application, we will aim at anticancer activity of SSA and SBA in prevention of colorectal tumor progression and metastasis, and focus on mechanism of action. Our recent results show that SS at sub-cytotoxic concentrations can efficiently inhibit the invasion of human colon tumor cells, which suggest that this drug may inhibit biological processes associated with metastasis. The mechanism of action appears to involve microRNAs (miRNAs), which are a set of small non-coding RNA molecules acting as master regulators of gene expression. A tumor suppressor miRNA, miR-200, was found to be up-regulated by SS and its non-COX inhibitory derivatives through the signaling pathway mediated by the transcriptional repressor snail. Given the documented tumor suppressive roles in promotion of apoptosis and inhibition of metastasis, we hypothesize that miR-200 is a key factor to mediate the non-COX anticancer activity of SSA and SBA for prevention of colorectal cancer. Three specific aims are proposed to address this hypothesis are: (1) to study the mechanistic basis of miR-200 in mediation of anticancer activities of SSA and SBA in vitro; (2) to study the role of miR-200 in mediating anticancer activities of sulindac in vivo; (3) to assess the clinical relevance of snail/miR-200/E-cadherin to human colorectal cancer progression. This application is being submitted in response to PA-12-213 and will address two research objectives: "determine the molecular pathways targeted by non-coding RNAs (ncRNAs) that predispose to cancer initiation or progression" and "determine whether interfering with oncogenic ncRNAs processing, target selection, or associated pathways prevent cancer progression". The proposed studies have the potential to impact human health by: 1) providing a mechanistic rationale in support of an ongoing national clinical trial studying prevention of colorectal cancer metastasis by sulindac; 2) evaluating novel non-COX inhibitory directives of sulindac to accelerate their preclinical development; and 3) identifying new therapeutic targets and/or biomarkers for clinical trials.