Increased activity of antagonists of growth hormone-releasing hormone substituted at positions 8, 9, and 10

Jozsef L. Varga, Andrew V. Schally, J. Horváth, Magdolna Kovacs, Gabor Halmos, Kate Groot, Gabor L. Toller, Z. Rékási, Marta Zarandi

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Antagonists of human growth hormone-releasing hormone (hGHRH) with increased potency and improved enzymatic and chemical stability are needed for potential clinical applications. We synthesized 21 antagonistic analogs of hGHRH(1-29)NH2, substituted at positions 8, 9, and 10 of the common core sequence {phenylacetyl-Tyr1, D-Arg2,28, para-chloro-phenylalanine 6, Arg9/homoarginine 9, Tyr 10/O-methyl-tyrosine 10, α-aminobutyric acid 15, norleucine 27, Har29} hGHRH(1-29)NH2. Inhibitory effects on hGHRH-induced GH release were evaluated in vitro in a su perfused rat pituitary system, as well as in vivo after i.v. injection into rats. The binding affinities of the peptides to pituitary GHRH receptors were also determined. Introduction of para-amidinophenylalanine 10 yielded antagonists JV-1-62 and -63 with the highest activities in vitro and lowest receptor dissociation constants (Ki = 0.057-0.062 nM). Antagonists JV-1-62 and -63 also exhibited the strongest effect in vivo, significantly (P <0.05-0.001) inhibiting hGHRH-induced GH release for at least 1 h. Para-amino-phenylalanine 10 and O-ethyltyrosine 10 substitutions yielded antagonists potent in vitro, but His10, 3,3′-diphenylalanine 10, 2-naphthylalanine 10, and cyclohexylalanine 10 modifications were detrimental. Antagonists containing citrulline 9 (in MZ-J-7-72), amidinophenylalanine 9 (in JV-1-65), His 9, D-Arg9, citrulline 8, Ala8, D-Ala 8, or α-aminobutyric acid 8 substituents also had high activity and receptor affinity in vitro. However, in vitro potencies of analogs with substitution in position 9 correlated poorly with acute endocrine effects in vivo, as exemplified by the weak and/or short inhibitory actions of antagonists JV-1-65 and MZ-J-7-72 on GH release in vivo. Nevertheless, antagonist JV-1-65 was more potent than JV-1-63 in tests on inhibition of the growth of human prostatic and lung cancer lines xenografted into nude mice. This indicates that oncological activity may be based on several mechanisms. hGHRH antagonists with improved efficacy could be useful for treatment of cancers that depend on insulin-like growth factors or GHRH.

Original languageEnglish
Pages (from-to)1708-1713
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume101
Issue number6
DOIs
Publication statusPublished - Feb 10 2004

Fingerprint

Growth Hormone-Releasing Hormone
Human Growth Hormone
Aminobutyrates
Citrulline
Phenylalanine
Homoarginine
Norleucine
Hormone Antagonists
Somatomedins
Nude Mice
Tyrosine
Lung Neoplasms
Prostatic Neoplasms
In Vitro Techniques
Peptides
Injections
Growth
Neoplasms

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Increased activity of antagonists of growth hormone-releasing hormone substituted at positions 8, 9, and 10. / Varga, Jozsef L.; Schally, Andrew V.; Horváth, J.; Kovacs, Magdolna; Halmos, Gabor; Groot, Kate; Toller, Gabor L.; Rékási, Z.; Zarandi, Marta.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 101, No. 6, 10.02.2004, p. 1708-1713.

Research output: Contribution to journalArticle

Varga, Jozsef L. ; Schally, Andrew V. ; Horváth, J. ; Kovacs, Magdolna ; Halmos, Gabor ; Groot, Kate ; Toller, Gabor L. ; Rékási, Z. ; Zarandi, Marta. / Increased activity of antagonists of growth hormone-releasing hormone substituted at positions 8, 9, and 10. In: Proceedings of the National Academy of Sciences of the United States of America. 2004 ; Vol. 101, No. 6. pp. 1708-1713.
@article{3ba851b1513c47179960ebeff404e646,
title = "Increased activity of antagonists of growth hormone-releasing hormone substituted at positions 8, 9, and 10",
abstract = "Antagonists of human growth hormone-releasing hormone (hGHRH) with increased potency and improved enzymatic and chemical stability are needed for potential clinical applications. We synthesized 21 antagonistic analogs of hGHRH(1-29)NH2, substituted at positions 8, 9, and 10 of the common core sequence {phenylacetyl-Tyr1, D-Arg2,28, para-chloro-phenylalanine 6, Arg9/homoarginine 9, Tyr 10/O-methyl-tyrosine 10, α-aminobutyric acid 15, norleucine 27, Har29} hGHRH(1-29)NH2. Inhibitory effects on hGHRH-induced GH release were evaluated in vitro in a su perfused rat pituitary system, as well as in vivo after i.v. injection into rats. The binding affinities of the peptides to pituitary GHRH receptors were also determined. Introduction of para-amidinophenylalanine 10 yielded antagonists JV-1-62 and -63 with the highest activities in vitro and lowest receptor dissociation constants (Ki = 0.057-0.062 nM). Antagonists JV-1-62 and -63 also exhibited the strongest effect in vivo, significantly (P <0.05-0.001) inhibiting hGHRH-induced GH release for at least 1 h. Para-amino-phenylalanine 10 and O-ethyltyrosine 10 substitutions yielded antagonists potent in vitro, but His10, 3,3′-diphenylalanine 10, 2-naphthylalanine 10, and cyclohexylalanine 10 modifications were detrimental. Antagonists containing citrulline 9 (in MZ-J-7-72), amidinophenylalanine 9 (in JV-1-65), His 9, D-Arg9, citrulline 8, Ala8, D-Ala 8, or α-aminobutyric acid 8 substituents also had high activity and receptor affinity in vitro. However, in vitro potencies of analogs with substitution in position 9 correlated poorly with acute endocrine effects in vivo, as exemplified by the weak and/or short inhibitory actions of antagonists JV-1-65 and MZ-J-7-72 on GH release in vivo. Nevertheless, antagonist JV-1-65 was more potent than JV-1-63 in tests on inhibition of the growth of human prostatic and lung cancer lines xenografted into nude mice. This indicates that oncological activity may be based on several mechanisms. hGHRH antagonists with improved efficacy could be useful for treatment of cancers that depend on insulin-like growth factors or GHRH.",
author = "Varga, {Jozsef L.} and Schally, {Andrew V.} and J. Horv{\'a}th and Magdolna Kovacs and Gabor Halmos and Kate Groot and Toller, {Gabor L.} and Z. R{\'e}k{\'a}si and Marta Zarandi",
year = "2004",
month = "2",
day = "10",
doi = "10.1073/pnas.0307288101",
language = "English",
volume = "101",
pages = "1708--1713",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "6",

}

TY - JOUR

T1 - Increased activity of antagonists of growth hormone-releasing hormone substituted at positions 8, 9, and 10

AU - Varga, Jozsef L.

AU - Schally, Andrew V.

AU - Horváth, J.

AU - Kovacs, Magdolna

AU - Halmos, Gabor

AU - Groot, Kate

AU - Toller, Gabor L.

AU - Rékási, Z.

AU - Zarandi, Marta

PY - 2004/2/10

Y1 - 2004/2/10

N2 - Antagonists of human growth hormone-releasing hormone (hGHRH) with increased potency and improved enzymatic and chemical stability are needed for potential clinical applications. We synthesized 21 antagonistic analogs of hGHRH(1-29)NH2, substituted at positions 8, 9, and 10 of the common core sequence {phenylacetyl-Tyr1, D-Arg2,28, para-chloro-phenylalanine 6, Arg9/homoarginine 9, Tyr 10/O-methyl-tyrosine 10, α-aminobutyric acid 15, norleucine 27, Har29} hGHRH(1-29)NH2. Inhibitory effects on hGHRH-induced GH release were evaluated in vitro in a su perfused rat pituitary system, as well as in vivo after i.v. injection into rats. The binding affinities of the peptides to pituitary GHRH receptors were also determined. Introduction of para-amidinophenylalanine 10 yielded antagonists JV-1-62 and -63 with the highest activities in vitro and lowest receptor dissociation constants (Ki = 0.057-0.062 nM). Antagonists JV-1-62 and -63 also exhibited the strongest effect in vivo, significantly (P <0.05-0.001) inhibiting hGHRH-induced GH release for at least 1 h. Para-amino-phenylalanine 10 and O-ethyltyrosine 10 substitutions yielded antagonists potent in vitro, but His10, 3,3′-diphenylalanine 10, 2-naphthylalanine 10, and cyclohexylalanine 10 modifications were detrimental. Antagonists containing citrulline 9 (in MZ-J-7-72), amidinophenylalanine 9 (in JV-1-65), His 9, D-Arg9, citrulline 8, Ala8, D-Ala 8, or α-aminobutyric acid 8 substituents also had high activity and receptor affinity in vitro. However, in vitro potencies of analogs with substitution in position 9 correlated poorly with acute endocrine effects in vivo, as exemplified by the weak and/or short inhibitory actions of antagonists JV-1-65 and MZ-J-7-72 on GH release in vivo. Nevertheless, antagonist JV-1-65 was more potent than JV-1-63 in tests on inhibition of the growth of human prostatic and lung cancer lines xenografted into nude mice. This indicates that oncological activity may be based on several mechanisms. hGHRH antagonists with improved efficacy could be useful for treatment of cancers that depend on insulin-like growth factors or GHRH.

AB - Antagonists of human growth hormone-releasing hormone (hGHRH) with increased potency and improved enzymatic and chemical stability are needed for potential clinical applications. We synthesized 21 antagonistic analogs of hGHRH(1-29)NH2, substituted at positions 8, 9, and 10 of the common core sequence {phenylacetyl-Tyr1, D-Arg2,28, para-chloro-phenylalanine 6, Arg9/homoarginine 9, Tyr 10/O-methyl-tyrosine 10, α-aminobutyric acid 15, norleucine 27, Har29} hGHRH(1-29)NH2. Inhibitory effects on hGHRH-induced GH release were evaluated in vitro in a su perfused rat pituitary system, as well as in vivo after i.v. injection into rats. The binding affinities of the peptides to pituitary GHRH receptors were also determined. Introduction of para-amidinophenylalanine 10 yielded antagonists JV-1-62 and -63 with the highest activities in vitro and lowest receptor dissociation constants (Ki = 0.057-0.062 nM). Antagonists JV-1-62 and -63 also exhibited the strongest effect in vivo, significantly (P <0.05-0.001) inhibiting hGHRH-induced GH release for at least 1 h. Para-amino-phenylalanine 10 and O-ethyltyrosine 10 substitutions yielded antagonists potent in vitro, but His10, 3,3′-diphenylalanine 10, 2-naphthylalanine 10, and cyclohexylalanine 10 modifications were detrimental. Antagonists containing citrulline 9 (in MZ-J-7-72), amidinophenylalanine 9 (in JV-1-65), His 9, D-Arg9, citrulline 8, Ala8, D-Ala 8, or α-aminobutyric acid 8 substituents also had high activity and receptor affinity in vitro. However, in vitro potencies of analogs with substitution in position 9 correlated poorly with acute endocrine effects in vivo, as exemplified by the weak and/or short inhibitory actions of antagonists JV-1-65 and MZ-J-7-72 on GH release in vivo. Nevertheless, antagonist JV-1-65 was more potent than JV-1-63 in tests on inhibition of the growth of human prostatic and lung cancer lines xenografted into nude mice. This indicates that oncological activity may be based on several mechanisms. hGHRH antagonists with improved efficacy could be useful for treatment of cancers that depend on insulin-like growth factors or GHRH.

UR - http://www.scopus.com/inward/record.url?scp=1242342212&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1242342212&partnerID=8YFLogxK

U2 - 10.1073/pnas.0307288101

DO - 10.1073/pnas.0307288101

M3 - Article

VL - 101

SP - 1708

EP - 1713

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

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

SN - 0027-8424

IS - 6

ER -