Clinicopathological and Prognostic Significance of MUC- 2, MUC-4 and MUC-5AC Expression in Japanese Gastric Carcinomas

Background: The mucin components of the gastric gel layer function as a protective and lubricatingfactor against luminal acid and proteolytic enzymes. Alteration of mucin expression in gastric preneoplasticand neoplastic lesions has suggested potential roles in neoplastic processes. This study aimed to assess theclinicopathological and prognostic significance of MUC-2, MUC-4 and MUC-5AC in Japanese gastric cancer.
Methods: Expression of MUC-2, -4 and -5AC was evaluated on tissue microarrays of gastric carcinomas andadjacent non-cancerous mucosa specimens by immunohistochemistry and compared with clinicopathologicalparameters and survival time of the patients.
Results: The three mucins were found to be expressed to a lesserextent in gastric carcinomas in comparison with non-cancerous mucosa (p<0.05). MUC-2 expression wasnegatively correlated with tumor size, depth of invasion, and TNM staging of gastric cancer (p<0.05), while thatof MUC-5AC was negatively associated with the depth of invasion, venous invasion, lymph node metastasis andTNM staging (p<0.05), but positively with MUC-4 and MUC-2 expression (p<0.05). There was higher MUC-2expression in intestinal- than diffuse-type carcinomas (p<0.05). Kaplan-Meier analysis indicated no relationshipbetween expression of the three mucins and the cumulative survival rate of patients, even stratified according tothe depth of invasion (p>0.05).
Conclusion: Down-regulated expression of MUC-2, -4 and -5AC may be involvedin pathogenesis, invasion, metastasis or differentiation of gastric carcinoma. Their altered expression mighttherefore be employed as an indicator of pathobiological behavior.