Relationship between MUC5AC and altered expression of MLH1 protein in mucinous and non-mucinous colorectal carcinomas.
The main purpose of this study was to examine the expression of mucins and mismatch repair proteins in colorectal carcinomas. The immunohistochemical distribution of apomucins MUC2, MUC5AC, and the expression of MLH1 and MSH2 proteins were examined in 76 mucinous and 60 non-mucinous colorectal carcinomas. MUC2 was noted in all mucinous carcinomas, whereas MUC5AC was present in 41 cases only (54%). In non-mucinous carcinomas, MUC2 was expressed in 61.7% of the tumors; by contrast, MUC5AC was present in 20% of the cases. The expression level of apomucins was significantly different in mucinous and non-mucinous lesions (p<0.001). Twenty-seven (35.5%) of the mucinous carcinomas showed no MLH1 expression, whereas 11 (18.3%) of the non-mucinous tumors did. This difference was statistically significant (p<0.005). Altered expression of MSH2 protein was never observed. The lack of MLH1 expression was considerably more frequent in carcinomas with secretion of MUC5AC (p<0.005). Our study has demonstrated this close relationship by immunohistochemical methods. In summary, our data show: (1) differences in the expression of mucins between mucinous and non-mucinous tumors; (2) a high frequency of altered MLH1 protein expression (35.5%) in mucinous carcinomas; (3) a significant relationship between the presence of MUC5AC and the altered expression of MLH1 protein in colorectal carcinomas.
Losi
Lorena
L
Department of Pathology, University of Modena and Reggio Emilia, Italy. losi.lo@policlinico.mo.it
Scarselli
Alessandra
A
Benatti
Piero
P
Ponz de Leon
Maurizio
M
Roncucci
Luca
L
Pedroni
Monica
M
Borghi
Francesca
F
Lamberti
Igor
I
Rossi
Giuseppina
G
Marino
Massimiliano
M
Ponti
Giovanni
G
Zangardi
Giovanni
G
Menigatti
Mirco
M
Di Gregorio
Carmela
C
D048868:Adaptor Proteins, Signal Transducing; D002288:Adenocarcinoma, Mucinous / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D002352:Carrier Proteins; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D055271:Mucin 5AC; D055262:Mucin-2; D009077:Mucins / Q000096:biosynthesis*; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D009687:Nuclear Proteins
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C501486:MLH1 protein, human; C524625:MUC2 protein, human; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D055262:Mucin-2; D009077:Mucins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000070957:MutL Protein Homolog 1