HORMONE SENSITIVITY OF THE R3327-G RAT PROSTATE ADENOCARCINOMA - GROWTH-RATE, DNA CONTENT, AND HORMONE RECEPTORS

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (6) , 2184-2190
Abstract
The growth of the R3327-G rat prostatic adenocarcinoma was significantly reduced when implanted in orchiectomized male rats (ORCH tumors). Tumors grown in intact animals (control tumors) had a doubling time of 7.4 days as compared to 9.2 days in ORCH tumors. A computer-based analysis of flow cytometric DNA histograms also detected significant differences between control and ORCH tumors. ORCH tumors had 25% fewer cells with hyperdiploid DNA than control tumors (P < 0.01). This androgen sensitivity in growth rate and the proportion of hyperdiploid cells were further reflected in the binding of [3H]R1881 binding capacity which was 70% lower than controls (6071 fmol/g tumor tissue). Nuclear [1H]R1881 binding in ORCH tumors was undetectable in 7 of 8 samples while in control tumors, binding was detectable in 5 of 6 preparations. Sucrose density gradient analysis showed that cytosolic [3H]R1881 showed that [3H]R1881 receptors were primarily androgenic, although some displacement by estradiol did occur. In contrast, [3H]estradiol binding was highly specific. The binding capacity of [3H]estradiol in ORCH tumor cytosols was 30% higher than controls (962 fmol/g tumor issue), while binding to ORCH and control nuclear extracts was similar. The inhibition of androgen-sensitive R3327-G tumor cells may be related to the concentration of androgen receptors. This in turn might be expressed as a reduction in the proportion of hyperdiploid cells.