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Growth hormone-releasing hormone antagonist MZ-5-156 inhibits growth of DU-145 human androgen-independent prostate carcinoma in nude mice and suppresses the levels and mRNA expression of insulin-like growth factor II in tumors.

Abstract：

:Insulin-like growth factors I and II (IGF-I and -II) are potent mitogens for various cancers, including carcinoma of the prostate. In several experimental cancers, treatment with antagonists of growth hormone-releasing hormone (GH-RH) produces a reduction in IGF-I and -II, concomitant to inhibition of tumor growth. To investigate the mechanisms involved, we treated male nude mice bearing xenografts of DU-145 human androgen-independent prostate cancer for 8 weeks with potent GH-RH antagonist MZ-5-156 at a dose of 20 microg/animal s.c. twice a day. Tumor growth, serum and tumor levels of IGF-I and -II, and the mRNA expression of IGF-I and -II in tumors were evaluated. After 8 weeks of therapy, final volume and weight of DU-145 tumors in mice treated with MZ-5-156 were significantly (P < 0.01) decreased compared with controls, and serum IGF-I showed a significant reduction. Treatment of nude mice bearing DU-145 xenografts with MZ-5-156 also significantly (P < 0.01) diminished by 77% the levels of IGF-II in tumor tissue compared with controls, but did not affect the concentration of IGF-I. Reverse transcription-PCR analyses revealed a high expression of IGF-II mRNA in DU-145 tumors. Treatment with GH-RH antagonist MZ-5-156 decreased the expression of IGF-II mRNA by 58% (P < 0.01) as compared with controls. Our work suggests that GH-RH antagonist MZ-5-156 may inhibit the growth of DU-145 human androgen-independent prostate cancers through a reduction in the production and mRNA expression of IGF-II by the tumor tissue. These findings extend our observations on the mechanism of action of GH-RH antagonists and may explain how GH-RH antagonists inhibit tumor growth.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Lamharzi N,Schally AV,Koppán M,Groot K

doi

10.1073/pnas.95.15.8864

subject

Has Abstract

pub_date

1998-07-21 00:00:00

pages

8864-8

issue

eissn

0027-8424

issn

1091-6490

journal_volume

pub_type

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Growth hormone-releasing hormone antagonist MZ-5-156 inhibits growth of DU-145 human androgen-independent prostate carcinoma in nude mice and suppresses the levels and mRNA expression of insulin-like growth factor II in tumors.