Molecular basis of endocrine-responsive cancers

Area of Science:

• Endocrinology and Molecular Biology
• Cancer Research
• Biochemistry

Background:

• Steroid hormone receptors regulate gene expression in target organs like the breast and uterus.
• Receptor analysis predicts therapeutic response and prognosis in breast and endometrial carcinomas.
• Traditional assays (titration, density gradient centrifugation) have limitations in characterizing receptor forms.

Purpose of the Study:

• To investigate the molecular heterogeneity and native state of steroid hormone receptors.
• To develop rapid and reliable methods for receptor isoform separation and characterization.
• To explore the physiological significance of different receptor forms and their interrelationships.

Main Methods:

• Established a reference laboratory for assay standardization and data uniformity.
• Utilized high-performance liquid chromatography (HPLC) in various modes (size-exclusion, ion-exchange, chromatofocusing, hydrophobic interaction) for rapid separation.
• Micropurification of estrogen receptor using affinity chromatography and monoclonal antibody precipitation.

Main Results:

• Demonstrated molecular heterogeneity (polymorphism) of steroid receptor proteins.
• Identified distinct receptor isoforms based on size, shape, and surface properties.
• Revealed association of purified estrogen receptor with protein and phospholipid kinase activities.

Conclusions:

• Steroid receptor organization and isoform interrelationships are more complex than previously understood.
• HPLC offers a powerful tool for rapid and comprehensive analysis of receptor isoforms.
• The discovery of kinase activities associated with estrogen receptors opens new avenues for understanding hormone signaling.