Aberration of p53 and DCC in gastric and colorectal cancer

We investigated the expression of p53 protein by immunohistochemistry and t he expression of deleted in colorectal carcinoma (DCC) mRNA by the reverse transcription-polymerase chain reaction (RT-PCR) method in surgically resec ted tumors of gastric and colorectal cancers and compared these results to the clinicopathological features. Positive immunoreactions of p53 were obse rved in 21 of 42 gastric cancers (50%) and 25 of 37 colorectal cancers (67. 6%). Decreased expression of DCC mRNA was observed in 15 of 38 gastric canc ers (39.5%) and 10 of 28 colorectal cancers (35.7%). There was a significan t correlation between the immunoreaction of p53 and the depth of tumor inva sion in gastric cancer, as well as between the decreased expression of DCC mRNA and nodal metastasis in colorectal cancer. In early cases without meta stasis and invasion beyond muscularis propria, none of six gastric cancers showed a p53 immunoreaction, while seven of 9 colorectal cancers showed pos itive immunoreactions. On the other hand, two of 4 gastric cancers showed d ecreased expression of DCC mRNA; whereas, none of the seven colorectal canc ers did. Alteration of p53 might occur at a later stage in gastric cancer t han in colorectal cancer and be associated with the acquisition of an invas ive character. In contrast to gastric cancer, decreased expression of DCC m RNA might be present in a later stage in colorectal cancer than in gastric cancer, and be related to the acquisition of metastatic character to the ly mph nodes. In conclusion, alterations of p53 or DCC may play different role s in the progression of gastric cancers as compared to colorectal cancers, and the occurrence of both p53 and DCC genes mutations may cause these canc ers to become more malignant.