MUC1, MUC2, MUC5AC, and MUC6 expressions in gastric carcinomas: their roles as prognostic indicators

Although mucin expressions appear to be correlated with prognoses in patients with various cancers, several studies have reported conflicting and inconclusive results on the prognostic significance of mucin expression in gastric carcinomas.

To clarify the correlations between clinicopathologic profiles and the patients' survival, the expression of MUC1, MUC2, MUC5AC, MUC6 mucins and the p53 protein were evaluated immunohistochemically in 300 consecutive gastric carcinomas using the tissue-array method. In addition, 59 gastric adenomas and 57 adenoma-associated carcinomas were investigated.

MUC1 was expressed in 2 (3.4%) cases of gastric adenoma, and MUC2 in 19 (32.2%) cases of gastric adenoma, out of a total of 59 lesions. In consecutive gastric carcinomas, 24.3% of gastric carcinomas expressed MUC1, 27.3% expressed MUC2, 38.0% expressed MUC5AC and 12.7% expressed MUC6. The rate of MUC1 expression in gastric carcinomas was significantly higher than in associated gastric adenomas (P < 0.01). The patients with MUC1-positive carcinomas showed significantly poorer survival than those with MUC1-negative carcinomas. On the other hand, MUC2, MUC5AC and MUC6 expressions were not significantly associated with patient survival. Interestingly, combined evaluation revealed that the group with the MUC1-negative plus p53-negative expression pattern showed a better prognosis than the remaining cases. In contrast, the group with the MUC2-negative plus p53-positive pattern showed a worse prognosis.

Mucin expression is altered in gastric adenoma and carcinoma, and MUC1 mucin expression is significantly associated with poorer outcome in gastric carcinomas. A MUC1-negative plus p53-negative pattern or a MUC2-negative plus p53-positive pattern may predict outcome in patients with gastric carcinomas.