USE OF GUANYLYL CYCLASE-C FOR DETECTING MICROMETASTASES IN LYMPH-NODES OF PATIENTS WITH COLON-CANCER

INTRODUCTION: Guanylyl cyclase C appears to be expressed only in color ectal cancer cells in extraintestinal tissues. Thus, guanylyl cyclase C may be useful as a marker to detect colorectal cancer micrometastase s not detectable by histopathology in lymph nodes of patients. METHODS : Twelve patients with colon adenocarcinoma, Dukes Stages A through C2 , and one patient with a tubulovillous adenoma were included in this s tudy. Forty-two lymph nodes were collected from fresh surgical specime ns, and each was examined by histopathology and reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specifi c primers. Histopathology identified colon cancer cells in 6 of 16 lym ph nodes from five Dukes Stage C patients but not in lymph nodes from the patient with a tubulovillous adenoma, the Dukes Stage A patient, o r six Dukes Stage B patients. Reverse transcription followed by polyme rase chain reaction using guanylyl cyclase C-specific primers was perf ormed on all 42 lymph nodes. RESULTS: Guanylyl cyclase C messenger RNA was not detected by reverse transcription followed by polymerase chai n reaction in lymph nodes from the patient with the tubulovillous aden oma or the patient with Dukes Stage A colon carcinoma. Seven lymph nod es from Dukes Stage C patients revealed guanylyl cyclase C messenger R NA including six lymph nodes containing histopathologically confirmed metastases. Of significance, guanylyl cyclase C messenger RNA. was det ected in 4 of 21 lymph nodes from Dukes Stage B patients. Indeed, clin ical staging of two patients could be upgraded from B to C using rever se transcription followed by polymerase chain reaction and guanylyl cy clase C-specific primers. CONCLUSION: Reverse transcription followed b y polymerase chain reaction using guanylyl cyclase C-specific primers might be useful to more accurately assess micrometastases in lymph nod es of colorectal cancer patients undergoing disease staging.