Predominant expression of mRNA coding for nonspecific cross-reacting antigen in colorectal carcinomas

We have analyzed specific transcripts of the carcinoembryonic antigen (CEA) gene family expressed in 32 colorectal carcinomas (CRCs) and when possible, their corresponding adjacent (less than 1 cm) and distant (greater than 10 cm) mucosas. From 1 of the 32 patients, we obtained a corresponding tubulovillous adenoma. From 1 additional patient a Crohn's disease sample was also evaluated. CEA mRNA was detectable by northern blot hybridization in 97% of the CRCs examined. Of these, 41% expressed this transcript at higher levels in the tumor than in the corresponding distant mucosa. Nonspecific cross-reacting antigen (NCA) is another member of the CEA gene family. The NCA mRNA was detectable in 87% of the CRCs examined, with 92% of these expressing the NCA mRNA at higher levels than the tubulovillous adenoma and the specimen from Crohn's colitis, whereas CEA was easily detected. Our findings demonstrate that NCA mRNA is more consistently overexpressed in colon carcinoma relative to distant mucosa than CEA mRNA.