A splice variant of the transcript for guanylyl cyclase C is expressed in human colon and colorectal cancer cells

Guanylyl cyclase C is a sensitive and specific biomarker for metastatic col orectal cancer. A variant of the guanylyl cyclase C transcript was identifi ed that possesses a 142-bp deletion at the 3' end of exon 1 reflecting alte rnative splicing of mRNA, introducing a shift in the open reading frame tha t prevents translation of a guanylyl cyclase C-related product, This varian t was identified in human intestine and colon carcinomas, but not in extrai ntestinal tissues or tumors. These studies demonstrate that GCC and the spl ice variant contribute to the pool of GCC transcripts detected by RT-PCR in human tissues. They indicate that primers for RT-PCR that amplify regions downstream from the deletion are required to assess the full complement of GCC transcripts (GCC + GCC(var)) in human tissues and body fluids far stagi ng and postoperative surveillance of patients with colorectal cancer.