Identification of carcinoembryonic antigen-producing cells circulating in the blood of patients with colorectal carcinoma by reverse transcriptase polymerase chain reaction.

Abstract

Application of the reverse transcriptase polymerase chain reaction (RT-PCR) to identification of circulating tumour cells in colorectal cancer. To assess whether circulating malignant cells in patients with colorectal liver metastasis could be identified by RT-PCR recognition of mRNA coding for the tumour marker carcinoembryonic antigen (CEA). A total of 31 with colorectal liver metastases and 22 no-cancer controls. Specific cDNA primers for CEA transcripts were used to apply RT-PCR to tissue biopsy specimens, colon carcinoma cell lines, and peripheral blood samples from patients with colorectal liver metastases. A strongly CEA-expressive HT115 colorectal carcinoma cell line was used to spike blood samples from no-cancer control subjects. The limit for detection of CEA cDNA by Southern blotting using HT115 cells was 50 cells per 14 ml of spiked blood. There was a significant difference (p = 0.007) in RT-PCR positive expression between patients with liver metastasis (26/31) compared with controls (5/22). There was no significant relation between the prevalence of CEA cDNA amplification and serum CEA level or metastasis volume in patients with liver metastasis. This is the first study to suggest that identification of circulating colorectal cancer cells using RT-PCR for detection of CEA cDNA is feasible.