Gastric M1 mucin, an early oncofetal marker of colon carcinogenesis, is encoded by the MUC5AC gene.
Gastric M1 mucin and the MUC5AC gene show a similar oncofetal expression in the colon. Our aim was to determine whether M1 mucin is the product of the MUC5AC gene. A recombinant baculovirus encoding the C-terminal portion of the MUC5AC gene as a fusion protein was isolated and the immunoreactivity of the recombinant mucin (rM) toward M1 antibodies studied. Chicken antibodies also were raised against purified rM. Besides its reactivity with L56/C, a serum recognizing the bacterially expressed MUC5AC gene product, rM was endowed with M1 immunoreactivity: (i) rM-expressing cells were stained specifically with anti-M1 serum and with the monoclonal antibody (MAb) 21M1, defining the M1-f epitope; (ii) both L56/C and anti-M1 antibodies recognized the same bands in immunoblots of rM-containing cell extracts; (iii) the 21M1 antibody reacted with rM in an immunoradiometric assay. Among the 7 M1 epitopes, M1-f was the only one encoded by the 3' portion of the MUC5AC gene. It was the only epitope detected in a native mucin M1-derived 170 kDa bromelain proteolytic fragment. Furthermore, the staining patterns of human tissues obtained with either anti-rM chicken antibodies or anti-M1 antibodies were identical. We conclude that M1 immunoreactivity is encoded at least in part by the MUC5AC gene.
Bara
J
J
INSERM U-55, Equipe Cancérogenèse et Différenciation de l'Epithélium Gastrointestinal, Hôpital Saint-Antoine, Paris, France. bara@adr.st-antoine.inserm.fr
Chastre
E
E
Mahiou
J
J
Singh
R L
RL
Forgue-Lafitte
M E
ME
Hollande
E
E
Godeau
F
F
D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics*; D016367:Baculoviridae; D002645:Chickens; D018604:Epitope Mapping; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007158:Immunologic Techniques; D051379:Mice; D055271:Mucin 5AC; D009077:Mucins / Q000235:genetics*; D011817:Rabbits; D051381:Rats; D011993:Recombinant Fusion Proteins; D018411:Spodoptera
D000951:Antigens, Neoplasm; C524678:MUC5AC protein, human; C524679:Muc5ac protein, mouse; C524680:Muc5ac protein, rat; D055271:Mucin 5AC; D009077:Mucins; D011993:Recombinant Fusion Proteins; C042384:gastro-intestinal mucus-associated antigens; C031192:oncofetal antigens