A peptide derived from α-fetoprotein prevents the growth of estrogen-dependent human breast cancers sensitive and resistant to tamoxifen

James A. Bennett, Fassil B. Mesfin, Thomas T. Andersen, John F. Gierthy, Herbert I. Jacobson

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48 Scopus citations

Abstract

An 8-mer peptide (EMTOVNOG) derived from α-fetoprotein was compared with tamoxifen for activity against growth of human breast cancer xenografts implanted in immune-deficient mice. Both peptide and tamoxifen prevented growth of estrogen-receptorpositive MCF-7 and T47D human breast cancer xenografts. A subline of MCF-7, made resistant to tamoxifen by a 6-month exposure to this drug in culture, was found to be resistant to tamoxifen in vivo. Peptide completely prevented the xenograft growth of this tamoxifen-resistant subline of MCF-7. Neither peptide nor tamoxifen was effective in slowing the xenograft growth of the estrogen-receptor-negative MDA-MB-231 human breast cancer. A worrisome side effect of tamoxifen is its hypertrophic effect on the uterus. In this study, tamoxifen was shown to stimulate the growth of the immature mouse uterus in vivo, and the peptide significantly inhibited tamoxifen's uterotrophic effect. The mechanism of action of peptide is different from that of tamoxifen in that the peptide does not interfere with the binding of [3H]estradiol to the estrogen receptor. In conclusion, α-fetoprotein-derived peptide appears to be a novel agent that interferes with the growth of tamoxifen-sensitive as well as tamoxifenresistant estrogen-receptor-positive human breast cancers; it inhibits the uterotrophic side effect of tamoxifen and, thus, it may be useful in combination with or in place of tamoxifen for treatment of estrogen-receptor- positive human breast cancers.

Original languageEnglish (US)
Pages (from-to)2211-2215
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number4
DOIs
StatePublished - Feb 19 2002
Externally publishedYes

ASJC Scopus subject areas

  • General

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