Histological changes in Dunning prostate tumors and testes of rats treated with LH-RH antagonist SB-75

K. Szepeshazi, E. Korkut, B. Szende, K. Lapis, A. V. Schally

Research output: Contribution to journalArticle

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Abstract

Rats bearing Dunning R-3327 hormone-dependent prostate tumors were treated with LH-RH antagonist SB-75 in the form of microcapsules for sustained delivery administered every 3 weeks and which released 24, 48, 72 μg/day respectively. The effects were compared with those of microcapsules of the agonist D-Trp-6-LH-RH releasing 25 μg/day. Both types of LH-RH analogs significantly inhibited tumor growth over a period of treatment lasting 8 weeks. The effect of SB-75 was dose-dependent. The total inhibition of spermatogenesis, as well as atrophic signs in the prostate and seminal vesicles, demonstrated a marked suppression of the pituitary-gonadal system by these analogs. The histological signs of tumor regression were analyzed. The vascular content of tumors did not change after the treatments, but an increased amount of connective tissue was found in the treated tumors, especially after administration of SB-75. Both the agonist and the antagonist caused a moderate decrease of the number of mitotic cells and a marked increase of apoptosis in the tumors. The apoptotic index, i.e. the percentage of tumorous glands showing signs of apoptosis, reached 40-50% in treated groups, compared to only 15% in controls. An apoptotic index of 60% was noted in a separate group of rats treated with 200 μg SB-75/animal/day for 3 days. The signs of enhanced apoptosis disappeared 1 week after the short-term treatment. The induction of apoptosis by LH-RH analogs seemed to be of greater importance in tumor growth inhibition than their antimitotic effect. These results extend our previous observations on the efficacy of LH-RH antagonists in inhibition of various cancers. This histopathologic evaluation clearly supports our contention that modern antagonists of LH-RH, free of edematogenic effects, inhibit the growth of Dunning prostate tumors. Because of the immediate inhibitory effects, the use of LH-RH antagonists might lead to an improvement in the clinical response in patients with prostate cancer.

Original languageEnglish
Pages (from-to)255-270
Number of pages16
JournalProstate
Volume18
Issue number3
Publication statusPublished - 1991

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Gonadotropin-Releasing Hormone
Testis
Prostate
Neoplasms
Apoptosis
Capsules
Growth
Triptorelin Pamoate
Antimitotic Agents
cetrorelix
Seminal Vesicles
Spermatogenesis
Connective Tissue
Blood Vessels
Prostatic Neoplasms
Cell Count
Hormones
Therapeutics

ASJC Scopus subject areas

  • Urology

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Histological changes in Dunning prostate tumors and testes of rats treated with LH-RH antagonist SB-75. / Szepeshazi, K.; Korkut, E.; Szende, B.; Lapis, K.; Schally, A. V.

In: Prostate, Vol. 18, No. 3, 1991, p. 255-270.

Research output: Contribution to journalArticle

Szepeshazi, K. ; Korkut, E. ; Szende, B. ; Lapis, K. ; Schally, A. V. / Histological changes in Dunning prostate tumors and testes of rats treated with LH-RH antagonist SB-75. In: Prostate. 1991 ; Vol. 18, No. 3. pp. 255-270.
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