Guanylyl cyclase C (GC-C), a receptor specifically expressed in cells originating from differentiated intestinal epithelium, is a marker and therapeutic target for
colorectal cancer metastases. Intestinal
metaplasia, in which epithelial cells assume histological and molecular characteristics of differentiated intestinal enterocytes, is a common precursor to
adenocarcinomas of the esophagus and stomach. Thus, those
tumors, tissues adjacent to them, and their associated regional lymph nodes were assessed for GC-C expression by reverse transcription coupled with the PCR. GC-C
mRNA was detected in five of five and eight of nine esophageal and gastric
adenocarcinomas, respectively. Also, GC-C
mRNA was detected in three of five and six of seven tissues adjacent to, but not histologically involved in, esophageal and gastric
adenocarcinomas, respectively, reflecting molecular changes associated with neoplastic transformation preceding histopathological changes. In contrast, three normal gastric specimens did not express GC-C. Furthermore, GC-C
mRNA was detected in 1 of 1 lymph node containing
tumor cells by histopathology from a patient with gastric
adenocarcinoma and in 3 of 11 lymph nodes, all of which were free of
tumor cells by histopathology, from a patient with a gastroesophageal junction
tumor. This is the first demonstration that GC-C is ectopically expressed by primary and metastatic
adenocarcinomas of the esophagus and stomach and suggests that GC-C may be a sensitive and specific
clinical marker and target for
adenocarcinomas of the upper gastrointestinal tract.