Specific Receptors and Growth Effects of Insulin and Insulin-Like Growth Factors in a Human Cell Line Derived From Mixed Mesodermal Tumor of the Uterus
Department of Obstetrics and Gynecology and Medicine, The University of Texas Medical Branch, Galveston, Texas Objective: Mixed mesodermal tumors of the uterus are highly malignant. The purpose of our present study was to investigate possible roles of insulin and insulin-like growth factors I and II (IGF-I and IGF-II) in the growth and development of these tumors. Methods: Specific binding and growth effects of insulin, IGF-I, and IGF-II were studied in SK-UT-1 cells, derived from a human mixed mesodermal tumor of the uterus. The receptors were further characterized by competitive binding and chemical cross-linking studies. Results: Binding studies with 125I-insulin, 125I-IGF-I, and 125I-IGF-II revealed the presence of specific binding sites for these three growth factors. Specificity studies revealed that the binding sites for IGF-I and IGF-II are distinct. Binding of IGF-II was much higher than insulin and IGF-I binding. Scatchard analysis of the binding data revealed that the cell line has a higher number of IGF-II receptors (100,000 sites per cell) than insulin (1400 sites per cell) and IGF-1 (1200 sites per cell) receptors. The effect of these growth factors on cell growth was studied by monitoring the cell number and incorporation of [3H] thymidine into the DNA of the cells. Insulin-like growth factor-II was potent in stimulating the growth of these cells, but IGF-I did not have any effect. Insulin stimulated DNA synthesis only at pharmacologic concentrations. Conclusion: These results indicate that IGF-II is mitogenic to mixed mesodermal tumors of the uterus. Insulin-like growth factor II may be involved in the growth regulation of mixed mesodermal tumors of the uterus.
Key Words: Mixed mesodermal tumors leiomyosarcoma IGF-II
Journal of the Society for Gynecologic Investigation, Vol. 3, No. 5,
281-288 (1996) |
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