Over 50,000 people die from colon cancer each year in the USA, making it the second leading cause of cancer death for men and women alike. Colon polyps are the usual precursors of colon cancer. Serrated polyps, which occur at a high incidence (20-30%) in the general population, were previously considered harmless. However, recent studies provide evidence that 20-35% of colon cancers arise from a subset of serrated polyps. Serrated polyps are divided into two main subtypes: sessile serrated adenomas/polyps (SSA/Ps) and traditional hyperplastic polyps. SSA/Ps appear to have the greatest risk of progressing to colon cancer whereas traditional hyperplastic polyps are considered benign. A major challenge is differentiating SSA/Ps from traditional hyperplastic polyps by endoscopic or histological examination. Moreover, we know little about their mechanism of progression to colon cancer. We predict that using new technologies to define the gene expression phenotype of SSA/Ps, as compared to traditional hyperplastic, adenomatous polyps and controls, will lead to important insights into the neoplastic progression of SSA/Ps, improve the diagnosis of SSA/Ps and eventually decrease the number of patients suffering from colon cancer due to SSA/Ps. We initially will study an extreme example of patients with SSA/Ps, the serrated polyposis syndrome. Patients with the serrated polyposis syndrome have a high rate of colon cancer, approximately 30-40%. The numerous SSA/Ps in these patients and their enriched cancer risk provide an outstanding opportunity to study SSA/Ps and their relationship to colon cancer. Our study includes one of the largest cohorts of such patients available. We have already obtained SSA/Ps and adjacent colon biopsy specimens from these patients and controls and have applied new RNA isolation and gene expression profiling technologies to study them. Our approach examines RNA polymerase II gene expression, with a markedly enhanced resolution, to find gene expression markers and advance our knowledge of the gene regulatory pathways altered in SSA/Ps. We hypothesize that our approach and unique patient cohort will identify panels of gene expression markers that more accurately diagnose SSA/Ps, predict their cancer risk and enable mechanistic studies of the progression of SSA/Ps to colon cancer. We have an outstanding team of experts, including Drs. Randy Burt (co-discoverer of the APC gene), Curt Hagedorn (RNA analysis and biology), Mary Bronner (GI pathology), David Nix (bioinformatics) and David Jones (colon cancer mechanisms and epigenetics) to successfully conduct this study of SSA/Ps as precursors of colon cancer.
One type of colon polyp previously considered harmless, sessile serrated adenomas/polyps (SSA/Ps), was recently found to account for up to 1/3rd of all colon cancers, the second leading cause of cancer deaths in the USA. However, it is difficult differentiating SSA/Ps from a similar type of polyp (traditional hyperplastic) that has little or n risk for cancer. We will use new technologies to identify molecular markers of SSA/Ps to develop diagnostic markers that distinguish them from other polyps, allow patients with a high risk for colon cancer to be identified and ultimately result in improved cancer treatment and prevention strategies for patients with SSA/Ps.
|Delker, Don A; McGettigan, Brett M; Kanth, Priyanka et al. (2014) RNA sequencing of sessile serrated colon polyps identifies differentially expressed genes and immunohistochemical markers. PLoS One 9:e88367|