Abstract: BACKGROUND AND AIM: To study the clinicopathological significance of p53 gene expression and telomerase activity in circulating tumor cells of patients with colorectal carcinoma. MATERIALS AND METHODS: Mononuclear cells containing circulating tumor cells were isolated by Ficoll-Hypaque gradient centrifugation in peripheral blood from 113 preoperative patients with colorecatal carcinomas,13 patients with benign colorectal disease, and 28 healthy volunteers. FCM and TRAP-ELASA were used to evaluate p53 gene expression and telomerase activity,respectively. Experimental data were analyzed by SPSS 11.0 software and χ2 test. RESULTS: Among 105 informative patients with colorectal carcinoma, positive rate of p53 expression and telomerse activity were 74.3％(78/105) and 61.0％(64/105),respectively. Aberrant expression levels of both p53 gene and telomerase in patients with colorectal cancer were significantly correlated with lymph node metastasis (P<0.05) and their simultaneous measurement could raise the prediction accuracy of metastasis. Expression of p53 gene was also significantly correlated with differentiation degree of colorectal carcinoma (P=0.003). CONCLUSION: Aberrant p53 gene expression and telomerase activity in circulating tumor cells might be malignant biomarkers. Both were closely related and could predict nodal involvement.

Key words: colorectal carcinoma, p53 gene, telomerase, metastasis, circulating tumor cells