Radioimmunoassay for human insulin-like growth factor-I receptor: applicability to breast carcinoma specimens and cell lines. |
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Authors: | V Pezzino G Milazzo L Frittitta R Vigneri O Ezaki M Kasahara T R LeBon I D Goldfine Y Fujita-Yamaguchi |
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Affiliation: | Cattedra di Endocrinologia, Università di Catania, Italy. |
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Abstract: | A radioimmunoassay for the human insulin-like growth factor-I (IGF-I) receptor was developed using a rabbit polyclonal antibody to the human IGF-I receptor and a highly purified IGF-I receptor. The purified receptor was radiolabeled with 125I-Bolton-Hunter reagent. Over 18% of the radiolabeled receptor was immunoprecipitated with the polyclonal antireceptor antibody. Purified IGF-I receptor concentrations as low as 5 ng/0.5 mL inhibited the radiolabeled IGF-I receptor binding. Purified insulin receptor weakly inhibited this binding, while the ligand IGF-I did not show inhibition. The radioimmunoassay was applicable to the measurements of IGF-I receptors in the Triton X-100 extracts of various tissues and cells. Breast cancer tissues and cells showed detectable IGF-I receptors, which correlated with IGF-I ligand binding. Receptor content was measurable in placenta and IM-9 cells, but receptor content was not measurable in liver and muscle extracts. |
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