Modulation of Genetic and Epigenetic Biomarkers of Colorectal Cancer in Humans by Black Raspberries: A Phase I Pilot Study

Abstract

Purpose: This study evaluated the effects of black raspberries (BRBs) on biomarkers of tumor development in the human colon and rectum including methylation of relevant tumor suppressor genes, cell proliferation, apoptosis, angiogenesis, and expression of Wnt pathway genes.Experimental Design: Biopsies of adjacent normal tissues and colorectal adenocarcinomas were taken from 20 patients before and after oral consumption of BRB powder (60 g/d) for 1-9 weeks. Methylation status of promoter regions of five tumor suppressor genes was quantified. Protein expression of DNA methyltransferase 1 (DNMT1) and genes associated with cell proliferation, apoptosis, angiogenesis, and Wnt signaling were measured.Results: The methylation of three Wnt inhibitors, SFRP2, SFRP5, and WIF1, upstream genes in Wnt pathway, and PAX6a, a developmental regulator, was modulated in a protective direction by BRBs in normal tissues and in colorectal tumors only in patients who received BRB treatment for an average of 4 weeks, but not in all 20 patients with 1-9 weeks of BRB treatment. This was associated with decreased expression of DNMT1. BRBs modulated expression of genes associated with Wnt pathway, proliferation, apoptosis, and angiogenesis in a protective direction.Conclusions: These data provide evidence of the ability of BRBs to demethylate tumor suppressor genes and to modulate other biomarkers of tumor development in the human colon and rectum. While demethylation of genes did not occur in colorectal tissues from all treated patients, the positive results with the secondary endpoints suggest that additional studies of BRBs for the prevention of colorectal cancer in humans now appear warranted.

A Phase Ib Study of the Effects of Black Raspberries on Rectal Polyps in Patients with Familial Adenomatous Polyposis

“…As noted previously (14), colorectal adenocarcinomas from patients with cancer who had consumed BRBs (60 g/d total) orally for at least 4 weeks had reduced levels of DNMT1 protein after berry treatment when compared with baseline. This observation was correlated with reduced methylation of p16 and multiple regulatory genes in the Wnt signaling pathway.…”

“…The camera was interfaced with a computer containing a matrix frame grabber board and image analysis software (Simple PCI Imaging Systems; Compix Inc.) as described before (14).…”

“…We recently reported that dietary BRBs hypomethylate p16 and Wnt signaling pathway inhibitor genes in colorectal adenocarcinomas (14). This effect was associated with reduced activity of the enzyme, DNA methylation methyl transferase 1 (DNMT1) in colorectal tumors (14).…”

“…This effect was associated with reduced activity of the enzyme, DNA methylation methyl transferase 1 (DNMT1) in colorectal tumors (14). DNMT1 is chiefly responsible for DNA methylation homeostasis, whereas two other methyl transferases; i.e., DNMT3a and DNMT3b, primarily catalyze de novo hypermethylation (18).…”

“…DNMT1 is chiefly responsible for DNA methylation homeostasis, whereas two other methyl transferases; i.e., DNMT3a and DNMT3b, primarily catalyze de novo hypermethylation (18). All three enzymes, DNMT1, DNMT3a, and DMNT3b, have been shown to be overexpressed in several tumor types, including colorectal cancer (14,19). Interestingly, both sporadic and FAP-related colon adenocarcinomas have common, for example, p16 and MGMT, as well as different, for example, PAX3, tumor-suppressor genes that are methylated, and hypermethylation seems to be a general feature of both sporadic and FAP-related carcinomas (20,21).…”