Abstract 1009: Regression of rectal polyps in familial adenomatous polyposis patients by freeze-dried black raspberries is associated with the demethylation and reactivation of tumor suppressor genes

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL We previously reported in a Phase I clinical trial that black raspberry (BRB) powder is well tolerated by humans when administered in a slurry of water at 45g/day for 7 days. We then undertook a study to determine if BRB might regress rectal polyps in familial adenomatous polyposis (FAP) patients. Fourteen FAP patients who had undergone a colectomy were treated with BRB daily for a period of nine months. Seven patients received BRB powder (20g/3x/day) orally in water plus two suppositories (each composed of 700 mg BRB) that patients inserted into the rectum one hour before bedtime. The other seven patients were randomized to receive an oral placebo plus the two rectal suppositories. Rectal polyp counts were taken at time zero and after nine months of BRB treatment. The number of rectal polyps was reduced by a median of 43% at nine months overall including a median reduction of 59% in patients treated by both routes and 36% in patients treated with the suppositories only. Polyps and aberrant crypt foci, both were histopathologically identified as tubular adenomas, and adjacent normal tissues were collected both before and after berry treatment. Promoter methylation of CDKN2A, also known as p16, in collected specimens was measured using MassARRAY. Global methylation LINE-1 was determined by Pyrosequencing. MBDCap-seq genome-wide methylation analysis was used to discover other genes demethylated by berries. Further, the specimens were evaluated for p16, Ki-67, TUNEL, DNMT1 and DNMT3B expression by semi-quantitative immunohistochemistry. Our results showed that treatment with BRB powder, both orally and in the form of a BRB suppository, significantly reduced cell proliferation in the tubular adenomas. The suppository alone was sufficient to decrease promoter methylation of p16 leading to an increase in p16 protein expression in adjacent normal rectum and in tubular adenomas. This was associated with decreased protein expression of DNMT1 and DNMT3B. Based on MBDCap-seq data, BRBs significantly demethylated promoter CpGs of 44 genes in tubular adenomas. These genes are involved in the regulation of important cellular functions; e.g., cell proliferation, Wnt signaling and Notch pathway, etc. Lastly, berry treatment did not induce changes in global methylation LINE-1. In conclusion, our data provide evidence that one of the mechanisms for BRB-induced rectal polyp regression in FAP patients is through the demethylation and reactivation of tumor suppressor genes.(Supported by NCI grants CA148818 and CA103180, and USDA grant 38903-03560). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1009. doi:1538-7445.AM2012-1009