An inverse relationship between the expression of the neu oncogene and estrogen receptors has been observed in breast cancer patients. In this study, we examined neu expression in the estrogen-induced and -dependent hamster kidney tumors, in kidney and in controls to evaluate the usefulness of this animal model far studying the regulation of genes important in hormonal cancer. The expression of neu mRNA was analyzed by Northern analysis and Neu oncoprotein localization by immunocytochemistry. The Neu oncoprotein was detected in several segments of proximal and distal kidney tubules, the loops of Henle and the parietal epithelial cells of Bowman's capsule but not in the tumor. neu mRNA was expressed in renal tissue after estrogen treatment and in untreated controls, but not in kidney tumors. The absence of Neu oncoprotein and mRNA from those cell types that have previously been shown to overexpress estrogen receptors in response to estrogen, suggests that the estrogen receptor and neu genes are interdependent in this tumor system, which may thus be a useful animal model for studying the regulation of neu by estrogens.

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