Gonadotropin-Releasing Hormone Specific Binding Sites in Normal and Malignant Renal Tissue

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Abstract
Renal cell carcinoma has been reported to contain estrogen and progesterone receptors. Thus, it has been suggested that these tumors are hormone dependent in a similar manner described for the breast and prostate cancers. It has been recently shown that mammary and prostate tumor cells contain gonadotropin-releasing hormone (GnRH) receptors and are growth inhibited directly by GnRH antagonists. In this study we examined for the presence of GnRH, estrogen and progesterone receptors in normal and malignant renal tissues. Estrogen receptors were found both in the normal and malignant kidney while progesterone receptors were present only in the normal tissue. Specific binding of [125I]buserelin, a GnRH agonist, was evident in renal carcinoma and in normal kidney and was displaced with equal efficiency by unlabeled buserelin and by D-Trp6-GnRH, but not by unrelated peptides such as thyrotropin releasing hormone and oxytocin. The non-linear scatchard curve obtained for buserelin binding, suggests the presence of at least two binding sites, one with high affinity in the nanomolar range and another in the micromolar range.