Characterization of the estrogen-induced pS2 protein secreted by the human breast cancer cell line MCF-7.
Our laboratory has reported previously the cloning of a complementary DNA termed pS2, corresponding to a messenger RNA (mRNA) whose synthesis is induced by estrogen in the human breast cancer cells MCF-7. Examination of the possible open reading frames of this complementary DNA has led to the prediction that the pS2 protein could be a secreted polypeptide of either 58 or 63 amino acids in length. Using a rabbit antiserum prepared against a synthetic peptide corresponding to the last 31 amino acids of the putative protein, we show that a protein with the expected migration during sodium dodecyl sulfate gel electrophoresis can indeed be immunoprecipitated from either the culture medium of MCF-7 cells grown in the presence of labeled amino acids or the in vitro translation products of MCF-7 poly(A) RNA enriched in pS2 mRNA. Furthermore, in vivo and in vitro differential amino acid labeling allows us to conclude that the mature pS2 protein is probably secreted as a 58 amino acid long peptide. Finally, we show that pS2 protein synthesis is induced in MCF-7 cells by estradiol and phenol red, but not by the antiestrogen tamoxifen, in keeping with our previous results demonstrating estrogen induction of pS2 mRNA synthesis.
Nunez
A M
AM
Laboratoire de Génétique Moléculaire des Eucaryotes, CNRS, Unité 184, Strasbourg, France.
Jakowlev
S
S
Briand
J P
JP
Gaire
M
M
Krust
A
A
Rio
M C
MC
Chambon
P
P
D001943:Breast Neoplasms / Q000378:metabolism*; D002460:Cell Line; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D010637:Phenolsulfonphthalein / Q000494:pharmacology; D014176:Protein Biosynthesis; D011506:Proteins; D012333:RNA, Messenger / Q000235:genetics; D013629:Tamoxifen / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins
D009363:Neoplasm Proteins; D011506:Proteins; D012333:RNA, Messenger; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D013629:Tamoxifen; D004958:Estradiol; D010637:Phenolsulfonphthalein