Differential expression of Neu messenger-RNA and protein in hamster-kidney and estrogen-induced kidney tumors
H Bhat1, I Springer, S Rajaraman
1UNIV TEXAS,MED BRANCH,DEPT PHARMACOL & TOXICOL,GALVESTON,TX 77555. UNIV TEXAS,MED BRANCH,DEPT PATHOL,GALVESTON,TX 77555.
Abstract:
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.
Insights
The neu oncogene and estrogen receptors show an inverse relationship in breast cancer. This study found neu expression in normal kidney tissue but not in hamster kidney tumors, suggesting interdependence for studying hormonal cancer regulation.
Area of Science:
- Oncology
- Molecular Biology
- Endocrinology
Background:
- An inverse relationship exists between neu oncogene expression and estrogen receptors in breast cancer patients.
- Estrogen plays a crucial role in hormonal cancers, necessitating the study of gene regulation.
Purpose of the Study:
- To evaluate a hamster kidney tumor model for studying the regulation of genes, specifically the neu oncogene, in hormonal cancer.
- To analyze neu expression in relation to estrogen in this animal model.
Main Methods:
- Northern analysis was used to examine neu mRNA expression.
- Immunocytochemistry was employed to determine Neu oncoprotein localization.
Main Results:
- Neu oncoprotein was detected in various normal kidney tubule segments and Bowman's capsule epithelial cells, but notably absent in tumors.
- Neu mRNA was present in both estrogen-treated and untreated normal renal tissue, but not in kidney tumors.
- The absence of Neu in estrogen receptor-overexpressing cells suggests interdependence.
Conclusions:
- The estrogen receptor and neu genes appear to be interdependent in this hamster kidney tumor system.
- This model may be valuable for investigating the regulation of neu by estrogens in the context of hormonal cancer.
