Altered expression of estrogen receptor alpha and beta in advanced gastric adenocarcinoma: Correlation with prothymosin alpha and clinicopathological parameters

Aims We aimed to investigate the sources of estrogen receptor alpha (ERα), estrogen receptor beta (ERβ) and estimate the value of both ER subtypes in gastric adenocarcinoma and analyze the possible relationship of prothymosin alpha (ProTα) to ERs. Methods ERs at the mRNA and protein levels in matched advanced gastric adenocarcinomas and surrounding non-cancerous tissues were examined by using reverse transcription-polymerase chain reaction and immunohistochemical (IHC) methods. Cell proliferation related protein ProTα was also detected in IHC. The immunoreactive signal, corresponding to the proteins expression level, was quantitatively analyzed. Results Both ERα and ERβ mRNAs were detected in most of the cancer and matched normal tissues analyzed. At the protein level, the percentage of ERα and ERβ positive cases changed. ERα immunoreactivity was only detected in poorly differentiated adenocarcinoma and ERα positive expression correlated with depth of invasion of the tumors. Compared with non-cancerous tissues, gastric tumors showed decreased ERβ expression and lost ERβ. Altered ERβ in gastric adenocarcinoma correlated with decreased differentiation. And the tumors involved lymph node metastasis showed significantly lower expression level of ERβ. ProTα in ERβ-positive tumors showed higher expression than that in lost ERβ tumors. Conclusions Altered expression of ERα and ERβ in tumors compared with corresponding normal gastric tissues was more common in poorly differentiated adenocarcinomas and related to malignant properties, such as lymph node metastasis. Decreased ERβ and increased ProTα expression in advanced gastric adenocarcinoma indicated that ERβ may play an anti-proliferation role which is opposed to the role of ProTα in gastric epithelium.