EXPRESSION OF THE LEUKOCYTE-ASSOCIATED SIALOGLYCOPROTEIN CD43 BY A COLON-CARCINOMA CELL-LINE

Citation
D. Baeckstrom et al., EXPRESSION OF THE LEUKOCYTE-ASSOCIATED SIALOGLYCOPROTEIN CD43 BY A COLON-CARCINOMA CELL-LINE, The Journal of biological chemistry, 270(23), 1995, pp. 13688-13692
Citations number
39
Categorie Soggetti
Biology
ISSN journal
00219258
Volume
270
Issue
23
Year of publication
1995
Pages
13688 - 13692
Database
ISI
SICI code
0021-9258(1995)270:23<13688:EOTLSC>2.0.ZU;2-C
Abstract
The colon adenocarcinoma cell line COLO 205 secretes L-CanAg, a mucin- like glycoprotein carrying the carcinoma-associated sialyl-Lewis a car bohydrate epitope. In an attempt to identify its apoprotein, an NH2-te rminal peptide sequence was obtained from purified L-CanAg. In all int erpretable positions, this sequence showed 100% identity to the NH2-te rminal of human CD43 (leukosialin, sialophorin), a plasma membrane bou nd sialoglycoprotein hitherto only identified in leukocytes and other hematopoietic cells. An antiserum against deglycosylated L-CanAg and a n anti-CD43 antiserum both immunoprecipitated a 61-kDa band, interpret ed as the CD43 precursor, from COLO 205 cells as well as hom the known CD43-expressing cell line HL-60. Results from immunoprecipitations fo llowing pulse-chase experiments and tunicamycin treatments were in agr eement with earlier studies on the CD43 precursor. RNA blot analysis c onfirmed the expression of CD43 by the COLO 205 cell line, whereas thr ee other colon carcinoma cell lines were negative. The glycosylation-d ependent monoclonal antibody Leu-22, which recognizes leukocyte CD43, failed to bind L-CanAg, probably due to its much more extensive glycos ylation, We conclude that L-CanAg is the secreted extracellular domain of a novel glycoform of CD43 and that CD43, if expressed in other car cinoma cells, may have escaped notice in studies relying on glycosylat ion-dependent monoclonal antibodies against leukocyte CD43.