Aberrant hypermethylation of the promoter region of the CHFR gene is rare in primary breast cancer

Abstract

Taxanes are among the most active agents and they are now known to be an indispensable component in chemotherapy for breast cancer. However, some patients are resistant to taxanes and the identification of the molecular characteristics that can predict the sensitivity to taxanes would be useful in selecting the most appropriate patients to receive taxane therapy. Taxanes are antimicrotubular agents that promote microtubular assembly and stabilize microtubules by preventing depolymerization. They interfere with normal mitotic transition and causes cell cycle arrest in the G2-M metaphase. CHFR (checkpoint with forkhead-associated and ring finger) is a recently identified gene, which functions as an important checkpoint protein early in G2-M transition. Its activation delays the cell cycle in prophase and promotes cell survival in response to the mitotic stress induced by either nocodazole or taxane. CHFR is frequently downregulated in human cancers, mostly owing to the hypermethylation of its promoter region. CHFR downregulation has been found in primary cancers or in the established tumor cells of various origins, such as the lung, colon, esophagus, and stomach. The aberrant hypermethylation of CHFR promoter appears to be a good molecular marker to predict sensitivity to taxanes in gastric, lung, and colon cancer. A downregulation of CHFR was observed in breast cancer cells, however, no apparent promoter hypermethylation has yet been reported. In addition, an alteration of the CHFR expression or aberrant promoter hypermethylation in primary breast cancer has not been fully investigated. In this study, we examined the methylation status of the promoter region of CHFR gene in 110 primary breast cancers. We observed the hypermethylation of the CHFR promoter region in only one case (0.9%). We herein show that the aberrant hypermethylation of this region is quite a rare event in primary breast carcinoma.