Chemopreventive role of folic acid in colorectal cancer.
Mortality from colorectal cancer, a leading cause of death in the U.S.A. and other western countries, has remained unchanged over the past 45 years. Therefore, the search for strategies to prevent the development and progression of colorectal cancer has markedly intensified. Chemoprevention is one such strategy. Accumulating evidence suggests that folic acid, a water soluble vitamin, could be an effective chemopreventive agent for colorectal cancer. Results from several studies have demonstrated that a diet deficient in folic acid may be associated with an increased risk of colonic neoplasia, whereas dietary supplementation of this nutrient may be chemopreventive. Although the mechanisms by which folic acid exerts its chemopreventive role in colorectal carcinogenesis remain to be fully elucidated, supplemental folic acid has been shown to arrest the loss of heterozygosity (LOH) of the tumor suppressor gene DCC (deleted in colorectal cancer) and to stabilize its protein in normal appearing rectal mucosa of patients with colorectal adenomas. Data from in vitro studies utilizing colon cancer cell lines suggest that supplemental folic acid or its metabolite 5-methyltetrahydrofolate (5-MTF) attenuates the expression and activation of EGF-receptor (EGFR) as well as proliferation of cells. The folic acid mediated reduction of EGFR function could partly be the result of suppression of EGFR gene through increased methylation of CpG sequences within its promoter.
Majumdar
Adhip P N
AP
Veterans Affairs Medical Center, Karmanos Cancer Institute, Department of Internal Medicine, Wayne State University, Detroit, Michigan 48201, USA. a.majumdar@wayne.edu
Kodali
Udayini
U
Jaszewski
Richard
R
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000517:prevention & control*; D018899:CpG Islands; D000075389:DCC Receptor; D019175:DNA Methylation; D066246:ErbB Receptors / Q000378:metabolism; D005492:Folic Acid / Q000494:pharmacology*; D006801:Humans; D019656:Loss of Heterozygosity; D011956:Receptors, Cell Surface / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics
D000075389:DCC Receptor; C501909:DCC protein, human; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; D005492:Folic Acid; D066246:ErbB Receptors