Antagonists of growth hormone-releasing hormone arrest the growth of MDA-MB-468 estrogen-independent human breast cancers in nude mice

Zsuzsanna Kahán, József L. Varga, Andrew V. Schally, Zoltán Rékási, Patricia Armatis, Ioulia Chatzistamou, Tamás Czömpöly, Gábor Halmos

Research output: Contribution to journalArticle

61 Scopus citations

Abstract

Since antagonists of growth hormone-releasing hormone (GH-RH) inhibit proliferation of various tumors, in this study we investigated the effects of GH-RH antagonists MZ-5-156 or JV-1-36 on growth of estrogen-independent MDA-MB-468 human breast cancers xenografted into nude mice. Both GH-RH antagonists administered at a dose of 20 μg/day induced regression of some and growth-arrest of other tumors, while control tumors continued to grow. After 5 weeks of therapy with MZ-5-156 or JV-1-36, final volume and weight of MDA-MB-468 tumors were significantly decreased (all p values < 0.001) and serum IGF-I levels as well as tumor IGF-I mRNA expression were reduced as compared with controls. High affinity binding sites for IGF-I were detected by the ligand binding method. Gene expression of human IGF-I receptors, as measured by the RT-PCR, was not significantly different in control and treated MDA-MB-468 tumors. In cell culture, IGF-I did not stimulate, GH-RH slightly stimulated, while MZ-5-156 and JV-1-36 inhibited proliferation of MDA-MB-468 cells known to possess defective insulin and IGF-I receptor signaling. The expression of mRNA for human GH-RH was found in five of 8 tumors treated with GH-RH antagonists, and in one of the five control tumors. These results suggest that GH-RH antagonists inhibit MDA-MB-468 breast cancers possibly through mechanisms involving interference with locally produced GH-RH.

Original languageEnglish (US)
Pages (from-to)71-79
Number of pages9
JournalBreast cancer research and treatment
Volume60
Issue number1
DOIs
StatePublished - May 31 2000

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Keywords

  • Breast cancer
  • GH-RH
  • Growth hormone-releasing hormone (GH-RH) antagonists
  • IGF-I
  • IGF-I receptor

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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