Reassessment of id1 protein expression in human mammary, prostate, and bladder cancers using a monospecific rabbit monoclonal anti-id1 antibody.
Id proteins are a class of dominant-negative antagonists of helix-loop-helix transcription factors and have been shown to control differentiation of a variety of cell types in diverse organisms. Although the importance of Id1 in tumor endothelial cells is well established, the expression and role of the Id1 protein in human cancer cells is controversial. To explore this issue, we developed and characterized a highly specific rabbit monoclonal antibody against Id1 to assess its expression in human breast, prostate, and bladder malignancies. Our results show that in usual types of human mammary carcinomas, the Id1 protein is expressed exclusively in the endothelium. Interestingly, we detected nuclear expression of the Id1 protein in the tumor cells in 10 of 45 cases of poorly differentiated and highly aggressive carcinoma with metaplastic morphology. Similarly, only 1 of 30 prostate cancer samples showed Id1-positive tumor cells, whereas in almost all, endothelial cells showed high Id1 expression. Intriguingly, whereas normal prostate glands do not show any Id1 protein expression, basal layer cells of benign prostate glands in proximity to tumors expressed high levels of the Id1 protein. In contrast to the lack of Id1 expression in the usual types of mammary and prostate cancers, the majority of transitional cell bladder tumors showed Id1 protein expression in both tumor and endothelial cells. These results suggest that further refinement of Id1 expression patterns in a variety of tumor types will be necessary to identify and study the functional roles played by Id1 in human neoplastic processes.
Perk
Jonathan
J
Cancer Biology and Genetics Program and Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Gil-Bazo
Ignacio
I
Chin
Yvette
Y
de Candia
Paola
P
Chen
John J S
JJ
Zhao
Yuntao
Y
Chao
Shirley
S
Cheong
Wai
W
Ke
Yaohuang
Y
Al-Ahmadie
Hikmat
H
Gerald
William L
WL
Brogi
Edi
E
Benezra
Robert
R
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D042783:Endothelial Cells / Q000473:pathology; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D051798:Inhibitor of Differentiation Protein 1 / Q000096:biosynthesis* / Q000276:immunology; D008297:Male; D015674:Mammary Neoplasms, Animal / Q000378:metabolism / Q000473:pathology; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D011817:Rabbits; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology
D000911:Antibodies, Monoclonal; C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1