The variable association between expression and methylation of estrogen receptors and the survival of patients with different tumors.

Background Estrogen receptor (ER) is essential in reproductive development and is also the primary driver of breast cancers. Deregulation of ER may also be involved in tumorigenesis of other organs. To understand the role of ER in different tumor types, pan-cancer analysis of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in various tumors and association with patients' survival were conducted using The Cancer Genome Atlas (TCGA) data. Results Gene methylation level was evaluated by the mean methylation level of CpG sites in the promoter region. The significant different DNA methylation between tumor and healthy tissues was shown in 10 tumor types for ESR1 and eight tumor types for ESR2. The methylation pattern was also varied across different TCGA tumors. The pan-cancer analysis showed significantly different mRNA expression of ESR1 in nine tumor types and ESR2 in four tumor types. Survival analysis showed that the effects of ERs expression on survival are diverse in different tumors. The expression of ERs was associated with tumor molecular subtypes and various clinical characteristics. ER correlated genes were mainly enriched in cancer and immune-related pathways. Conclusions Our pan-cancer analysis data indicated that ERs might be significantly associated with carcinogenesis and progression of some tumors, which may be potential therapeutic targets and prognosis biomarkers.