Abstract: Objective To detect promoter methylation status and mRNA expression level of GATA5 and to explore the relationship between methylation and mRNA expression in invasive breast cancers (IBC). Methods Promoter methylation analysis of GATA5 was performed by methylation-specific PCR (MSP) in IBC and matched normal tissues (MNT) from 62 patients. We examined expression profile of GATA5 using quantitative real-time PCR (qRT-PCR) analysis in 48 of 62 patients. Results Methylation of GATA5 was only present in IBC (48.4% (30 of 62)) (P < 0.001). mRNA expression of GATA5 in IBC showed the lower level than that in MNT (P < 0.001). For GATA5, methylated IBC only showed significantly lower expression values compared to MNT (P < 0.001). Tumors with methylated GATA5 showed significantly less fold change of GATA5 than tumors without methylation (P < 0.05). Conclusions Methylation of GATA5 maybe is one important mechanism of the gene transcriptional inactivation, and is associated with the formation and development of IBC.

Key words: Key words: invasive breast cancers, methylation, mRNA expression, GATA5