Expression of estrogen receptor-α and -β mRNAs in human gastric cancer

To clarify the roles of estrogen receptors (ERs) in gastric cancers, we evaluated expression of ER-α and ER-β mRNAs in 41 pairs of tumorous and non-tumorous tissues of gastric cancer patients and in six gastric cancer cell lines by reverse transcription-polymerase chain reaction method. ER-α and ER-β mRNAs were detected in 21 (51%) and 30 (73%) of 41 tumors and in 15 (37%) and 36 (88%) of 41 corresponding normal tissues, respectively. There were no statistically significant associations between expression of ER-α and/or ER-β mRNAs in tumors and clinicopathologic factors. Between the tumorous and normal tissues, expression of ER-α and ER-β mRNAs were changed in 20 (49%) and unchanged in 21 (51%) of the 41 cases. The incidences of lymph node metastasis and liver metastasis were significantly higher in changed cases than in unchanged cases (P=0.031 and P=0.021, respectively). We confirmed that ER-α and ER-β mRNA were expressed in 2 and 6 of the six gastric cancer cell lines, respectively. Together with this finding, our results indicate that ER-β mRNAs are preferentially expressed in gastric cancers. Our data also suggest that altered expression of ER-α and ER-β mRNAs in tumors compared with corresponding normal gastric tissues is related to increased metastatic potential in gastric cancers. Further studies are needed to clarify the role of ERs in gastric cancers.