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Immunological probes for oestradiol receptors in human breast tumours
Abstract:
Monoclonal antibodies have been prepared against a soluble oestradiol receptor (REC) preparation partially purified from human myometrium by oestradiol affinity chromatography. The antibodies were detected by their ability to immunoprecipitate receptor bound [125I] oestradiol. One of the antibodies (D5) has been studied in detail. It will only precipitate REC after activation by salt, heat, low pH or KCNS and will not react with nuclear RE. It will not react with androgen, progesterone or glucocorticoid receptors nor with sex hormone binding globulin; it will only combine with REC from human sources. D5 recognizes a cytoplasmic 29 kdalton protein (p29) that can be separated from both type I and II soluble oestradiol binding proteins. p29 can react with activated REC and is qualitatively and quantitatively related to REC. IRMA and histochemical methods have been developed for quantitating p29 and relating its amount to receptors in human breast tumours. With both methods, highly significant (P less than 0.001) correlations with REC but not RP have been obtained. Both methods indicate that many REC-RP+ tumours contain p29. The histochemical method detects marked cellular heterogeneity in some tumours. The function of p29 is not known. It is an REC-related antigen that may be a previously undetected component of the oestradiol receptor machinery.
Insights
Researchers developed antibodies to study the oestradiol receptor (REC). A specific antibody (D5) targets a related protein (p29), potentially a new component of the oestradiol receptor machinery in human breast tumors.
Area of Science:
- Endocrinology
- Molecular Biology
- Oncology
Background:
- Oestradiol receptors (REC) play crucial roles in various physiological processes.
- Understanding REC composition and regulation is vital for disease research, particularly in hormone-dependent cancers.
Purpose of the Study:
- To generate specific antibodies against the human myometrium oestradiol receptor (REC).
- To characterize a novel REC-related antigen (p29) and its potential role in breast tumors.
Main Methods:
- Preparation and characterization of monoclonal antibodies against partially purified human myometrium REC.
- Immunoprecipitation assays to detect antibody binding to [125I] oestradiol-bound REC.
- Development of immunoradiometric assay (IRMA) and histochemical methods for p29 quantitation.
Main Results:
- A specific antibody (D5) was generated, recognizing an activated cytoplasmic form of REC.
- D5 identified a 29 kDa protein (p29) antigenically related to REC, distinct from known soluble binding proteins.
- Quantitation of p29 in human breast tumors showed significant correlation with REC, not progesterone receptors (RP), and revealed cellular heterogeneity.
Conclusions:
- A novel REC-related antigen, p29, has been identified and characterized.
- p29 is present in human breast tumors and correlates with REC levels, suggesting its involvement in the oestradiol receptor machinery.
- Further research is needed to elucidate the precise function of p29.