Correlation of expression of DNA methy transferases 1 and estrogen receptor alpha with methylation status of estrogen receptor alpha and its clinical significance in breast cancer

Abstract

Objective To investigate the correlation of DNA methy transferases 1(DNMT1)and estrogen receptor alpha(ERα)expression with ERαmethylation and its clinical significance in normal breast specimens and breast cancer specimens. Methods Immunohistochemistry and reverse transcription-polymerase chain reaction(RT-PCR) were used to detect the protein and m RNA expression of DNMT1 and ERαin 20 cases of normal breast specimens and 112 cases of breast cancer specimens.Mutagenically separated polymerase chain reaction(MS-PCR) was used to detect the methylation status of ERαin different specimens. Results Immunohistochemistry and reverse RT-PCR results showed that the positive rate of DNMT1 protein and m RNA was low in normal breast specimens and ERαpositive breast cancer specimens, which was 10. 00% and 46. 05%, and 15. 00% and 48. 68% respectively, while it was high in ERα-negative breast cancer specimens, which was 81. 11% and 88. 89% respectively(P< 0. 05). MS-PCR results revealed that the methylation rate of ERαwas increased by turns in normal breast specimens, ERα-positive breast cancer specimens and ERαnegative breast cancer specimens, which was 10. 00%, 36. 84% and 86. 11% respectively(P< 0. 05).The expression of DNMT1 was positively correlated to the methylation of ERα(P< 0. 05). Conclusion In breast cancer specimens, the protein and mRNA expression of DNMT1 was negatively correlated to the expression of ERα; the expression of DNMT1 was positively correlated to the methylation of Cp G island of ERα. Key words: Breast cancer; DNA methyltransferase 1; Estrogen receptorα; Methylation