Expression of Mad1 protein inhibits proliferation of cancer cells and inversely correlated with Myc protein expression in primary gastric cancer.

We performed immunohistochemical assay for Mad1 and Myc protein in 76 gastric cancer tissues. Cancers with reduced Mad1 expression had high proliferative index (S and G2/M-phase) and there was inverse correlation between Mad1 and Myc expression in the same cancer cells. There was no significant correlation between expression of Mad1 and cell differentiation or extent of the disease. There was a trend that reduced expression of Mad1 was associated with poor survival of the patients. Mad1 may influence biologic behavior of cancer cell by inhibiting transcriptional activity of Myc and reduced levels of Mad1 expression seem to be associated with carcinogenesis in human gastric cancer.