Isolation & Partial Purification of Testosterone Receptors in Benign & Malignant Prostatic Tumors

Abstract

Background: A gel filtration technique has been used for the isolation and purification of soluble testosterone receptors from benign and malignant prostatic tumors. Two types of testosterone receptors from benign and malignant prostatic tumors were eluted from the sephadex G-200 column. This work was carried out to characterize and quantify human nuclear androgen receptors from benign and malignant prostatic tumors.Methods: The study involved twenty five patients with benign prostatic hyperplasia (BPH) and thirteen patients with prostatic adenocarcinoma (PCA) attending Al-Kadhimiya teaching hospital from the period of November 2005 till july 2006.Results: The purification folds of two benign separated receptors (BI & BII) were 11.588 and 19.582 fold respectively whereas for the two malignant separated receptors (MI & MII) were 24.280 and 29.111 fold respectively.The choice of most appropriate conditions of the binding of 125I-testosterone with its receptors were also carried out.The concentrations of binding sites and the equilibrium dissociation constants for the binding between 125I-testosterone and its purified receptors have been determined using Scatchrad analysis and the specificity of the binding has been examined. The concentrations of two benign separated receptors (BI & BII) were 0.931 and 1.140 pmole/mg protein respectively whereas separated malignant receptors (MI & MII) have 1.056 and 2.163 pmole/mg protein respectively at 37ºC.Conclusions: Gel filtration technique and Scatchard analysis confirmed the presence of two types of testosterone receptors in each tumor type. The first eluted receptor (I) has a relatively higher molecular weight with a lower affinity constant for testosterone binding than the other(II).