Objective:To investigate the expression of cyclooxygenase-2 (COX-2)and proliferation cell nuclear antigen (PCNA)in colorectal carcinoma

and to identify the correlation between these expressions with the clinical biological features. Methods:The levels of COX-2 and PCNA mRNA were detected with quantitative reverse transcription-polymerase chain reaction (QRT-PCR)in 40 pairs of samples containing tumor tissues and the non-cancerous tissues. The level of PGE2 in peripheral blood was detected by ELISA. Data of COX-2 and PCNA mRNA were statistically analyzed along with the corresponding clinicopathological features. Results:The mRNA transcription levels of COX-2 and PCNA in tumor tissues were significantly higher than that in the non-cancerous tissues (P<0.01). A significant difference was found in mRNA transcription levels for COX-2 and PCNA among patients with tumors of different degrees of invasion depth and the differentiation. The mRNA transcription level of COX-2 was significantly different between patients with and without lymph node metastasis(P<0.05)

which was not found in PCNA. COX-2 mRNA expression was correlated with PCNA in colorectal cancer (P<0.01). The PGE2 levels in postoperative plasma of colorectal cancer was significantly lower than that in preoperative plasma (P<0.01)

but still higher than the normal plasma (P<0.05). Conclusion:COX-2 and PCNA play important roles in carcinogenesis of colorectal cancer . Measurement of PGE2 might be helpful in the early detection and diagnosis of colorectal cancer.