Does human melanoma express carcinoembryonic antigen?
BACKGROUND
Several investigators have proposed that carcinoembryonic antigen (CEA), an immunogenic antigen expressed by colon carcinoma, may also be expressed by human melanoma. Because sialyl Lewisx (sLex), the carbohydrate moiety of CEA, has been identified in melanoma, we compared CEA and sLex levels in colon carcinoma cells and melanoma cells.


METHODS
CEA levels were assessed for expression on the cell surface and in cell lysates of cutaneous melanoma cell lines by two different kinds of ELISA, and by Western blot analysis of immunoprecipitated CEA using monoclonal antibodies (Mabs) T84-66 and COL-1, which have defined specificities for CEA. Colon carcinoma cells and purified CEA were positive controls.


RESULTS
Both Mabs reacted strongly with cell surface and cell lysates of colon cancer. Mab T84-66 reacted well with cell surface but not cell lysates of melanoma. COL-1 reacted poorly with cell surface but its binding increased with the density of melanoma cell lysates. Both Mabs intensely stained the blots of purified CEA and colon carcinoma lysates immunoprecipitated with the respective Mabs, but failed to stain the immunoprecipitates of melanoma cell lysates. Both Mabs bound to lysates immunoprecipitated with anti-sLex Mab in colon carcinoma, but not in melanoma. Cell-surface expression of CEA and sLex was significantly correlated (r2: 0.88) in colon cancer cells but not in melanoma.


CONCLUSIONS
Our results confirm the presence of CEA in colon carcinoma but not in human cutaneous melanoma cell lines.
Ravindranath
M H
MH
Laboratory of Glycoimmunotherapy, John Wayne Cancer Institute, Santa Monica, CA 90404-2302, USA. Ravi@jwci.org
Shen
P
P
Habal
N
N
Soh
D
D
Nishimoto
K
K
Gonzales
A
A
Tam
W Y
WY
Bilchik
A
A
Morton
D L
DL
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002272:Carcinoembryonic Antigen / Q000096:biosynthesis*; D003110:Colonic Neoplasms / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D008545:Melanoma / Q000276:immunology*; D051379:Mice; D009844:Oligosaccharides / Q000378:metabolism; D011233:Precipitin Tests / Q000379:methods; D000080506:Sialyl Lewis X Antigen; D012878:Skin Neoplasms / Q000276:immunology*; D014407:Tumor Cells, Cultured
D002272:Carcinoembryonic Antigen; D009844:Oligosaccharides; D000080506:Sialyl Lewis X Antigen