Role of estrogen receptors in the growth of human esophageal carcinoma.

In order to investigate the role of estrogen receptors (ER) in the growth of human esophageal carcinoma, tumor tissues of ER-positive but androgen receptor (AR)-negative line of squamous cell carcinoma (ES-8) were transplanted in ten male and ten female nude mice. As control, those of a tumor line without both receptors (ES-13) derived from human esophageal cancer were used. The growth rates of transplanted tumors were estimated up to 5 weeks. The tumor growth of ES-8 line was significantly greater in males than it was in females. Such a difference was not observed for ES-13 line. Moreover, in order to investigate the effect of estrogen on the ER, tumor tissues of ES-8 line were transplanted in six oophorectomized female mice, and next, estradiol (E2) (500 micrograms/kg, 50 micrograms/kg, or none) was administered to five transplanted female mice of each group, respectively. The growth rates of tumors were enhanced in oophorectomized female mice, and significantly suppressed with the physiologic dose (50 micrograms/kg) of E2 compared to the control. The current results seem to indicate that the inhibitory effect of estrogen on the tumor line is mediated by ER.