[A relationship between cyclooxygenase-2 expression and tumor angiogenesis in experimental rat liver carcinogenesis]

To explore the relationship between the expression of cyclooxygenase-2 (COX-2) and angiogenesis in hepatocellular carcinoma.

Forty Wistar rats were divided into two groups: a model group (30 rats) and a normal group (10 rats). Hepatocellular carcinoma was induced with 0.01% diethylnitrosamine (DEN) in the model group rats. The rats were sacrificed in batches at the 6th, 12th and 18th week of the experiment. Histological sections of liver tissues were made using routine methods. The expressions of COX-2, VEGF, VEGFR-2/KDR, and MMP-2 protein in the liver tissues were evaluated using immunohistochemical methods.

In liver sections from the model group there were marked pathological changes (steatosis, cell infiltration, cirrhosis and liver cancer). The expressions of VEGF, VEGFR-2/KDR, and MMP-2 in those liver tissues were remarkably increased during the hepatocellular carcinogenesis. Microvessel density (MVD) was also obviously raised during the process of the cancer development. There was a direct correlation between the MVD and VEGF/KDR/MMP-2 (r=0.858, 0.788, 0.684, respectively; all P less than 0.01). There was also a direct correlation between the COX-2 and VEGF/KDR/MMP-2/MVD (r=0.771, 0.599, 0.690, 0.788, respectively; all P < 0.01).

COX-2 can promote tumor angiogenesis during rat hepatocellular carcinogenesis. This may be one of the mechanisms in which COX-2 promotes carcinomas.