Characterization of Bombesin/Gastrin-releasing Peptide Receptors in Human Breast Cancer and Their Relationship to Steroid Receptor Expression

Gabor Halmos, James L. Wittliff, Andrew V. Schally

Research output: Contribution to journalArticlepeer-review

109 Scopus citations

Abstract

Bombesin (BN) and its mammalian counterpart, gastrin-releasing peptide (GRP), are hormonally active peptides which appear to function as autocrine or paracrine growth factors in a variety of cells. As part of a long-term investigation of the relationship of peptide and steroid hormone receptors to breast cancer progression and treatment, we examined the binding of [125I- Tyr4]BN to membranes isolated from 100 human breast carcinomas. Thirty- three of these tumors expressed BN/GRP receptor levels of >10 fmol/mg membrane protein. Two classes of [Tyr4]BN-binding sites were detected using Scatchard analyses of radioligand association data from hormone displacement curves. The high-affinity binding sites exhibited a mean dissociation constant (K(d1)) of 2.1 nM and a mean specific binding capacity (B(max)) of 237 fmol/mg membrane protein. The low affinity binding sites had a mean dissociation constant (K(d2)) of 0.3 μM and a mean binding capacity (B(max)) of 5.9 pmol/mg membrane protein. BN/GRP receptor expression in a breast carcinoma was unrelated to patient age. When the levels of BN/GRP receptors were compared to the content of the sex steroid receptors, a highly significant positive correlation (P < 0.005) was observed between the binding capacities of high-affinity [Tyr4]BN-binding sites and estrogen receptor levels and between the concentrations of low affinity [Tyr4]BN-binding sites and progestin receptor levels (P < 0.05). This represents the first report of these labile, regulatory proteins in biopsies of human breast carcinomas. Expression of specific receptor proteins for BN/GRP, potent mitogens, in a large number of human breast cancers suggests that they may be involved in tumor cell progression. The approach based on determination of BN/GRP receptors might be useful to guide a hormonal therapy with BN/GRP antagonists in some women with breast cancer.

Original languageEnglish (US)
Pages (from-to)280-287
Number of pages8
JournalCancer Research
Volume55
Issue number2
StatePublished - Jan 15 1995
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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