Chromodomain
helicase DNA binding protein 5 (CHD5) has been identified as a
tumor suppressor in mouse models. Downregulation of CHD5 gene expression is frequently observed in
breast cancer cells and tissues. This may be explained by deletions or other mutations; however, alternative mechanisms require investigation. Therefore, the present study evaluated whether CHD5 aberrant methylation has a role in primary
breast tumors. A total of 389 patients with primary
breast cancer (including 252
paraffin-embedded specimens and 137 fresh-frozen samples) were enrolled in the present study. In the current study, reverse transcription-polymerase chain reaction (RT-PCR) and nested-methylation-specific PCR were used to analyze the
mRNA expression and promoter methylation of CHD5 genes in a large cohort of
breast cancer patients, and to investigate their associations with the clinicopathological features of
tumors. CHD5 expression was significantly suppressed in
breast cancer tissues compared with normal breast tissues when analyzed by RT-PCR. Furthermore, DNA methylation of CHD5 was more prevalent in
breast tumors than in normal tissues. CHD5
mRNA levels correlated with the degree of CHD5 methylation in
breast cancer tissues. Clinicopathological correlation analysis revealed that CHD5 promoter methylation was associated with
estrogen receptor and
progesterone receptor status. Thus, downregulation of CHD5, mediated by abnormal methylation, may contribute to the development and progression of
breast cancer.