Estrogen Receptor-beta Gene Cytosine-Adenine (ESR2-CA) Repeat Polymorphism in Postmenopausal Colon Cancer

The pathobiological role of estrogen is controversial in colorectal cancer. Cytosine-adenine (CA) repeat in the estrogen receptor (ER)-beta gene (ESR2-CA) is a microsatellite, as well as representative of ESR2 polymorphism. Though its function is unknown, we previously showed that a shorter allele (germline) increased the risk of colon cancer in older women, whereas it decreased it in younger postmenopausal women. ESR2-CA and ER-beta expressions were examined in cancerous (Ca) and non-cancerous (NonCa) tissue pairs from 114 postmenopausal women, and comparisons were made considering tissue types, age/locus, and the mismatch repair protein (MMR) status. ESR2-CA repeats < 22/>= 22 were designated as "S'/"L', respectively, resulting in genotypes SS/nSS (=SL&LL). In NonCa, the rate of the SS genotype and ER-P expression level were significantly higher in right-sided cases of women >= 70 (>= 70Rt) than in those in the others. A decreased ER-beta expression in Ca compared with NonCa was observed in proficient-MMR, but not in deficient-MMR. In NonCa, but not in Ca, ER-beta expression was significantly higher in SS than in nSS. >= 70Rt cases were characterized by NonCa with a high rate of SS genotype or high ER-beta expression. The germline ESR2-CA genotype and resulting ER-beta expression were considered to affect the clinical characteristics (age/locus/MMR status) of colon cancer, supporting our previous findings.