Expression of phospholipase D2 in human colorectal carcinoma

Phospholipase D (PLD) catalyzes the hydrolysis of phosphatidylcholine (PC) to generate phosphatidic acid (PA) and choline. PA acts as a second messenger in cell proliferation; therefore PLD is believed to play an important role in carcinogenesis. PLD activity has been reported to be elevated in human breast, gastric, renal cell and colorectal carcinomas, compared with adjacent non-neoplastic tissues. The activity of PLD was also correlated with nuclear grade in breast cancer, tumor size in gastric carcinoma, and nodal involvement and deeper invasion in colorectal carcinoma. However, the number of cases in each study was small. The aim of this study was to investigate the expression level of PLD2 and its association with clinicopathological features in human colorectal carcinoma. Ninety-seven colorectal carcinomas were obtained from surgery. Expression level of PLD2 was assessed by real-time PCR. The prognostic relevance of PLD2 expression level in patients with colorectal carcinoma was also analyzed by the survival analysis of mortality follow-up data covering the period 2000-2004. PLD expression level was varied from tumor to tumor. Expression level of PLD was significantly correlated with tumor size (P<0.05); it was independent of lymph node metastasis, extent of invasion, pathological classification, distant metastasis and Dukes' stage. PLD expression level was also significantly correlated with survival of patients with colorectal carcinoma (P<0.05). These findings suggested that PLD2 plays an important role in progression of colorectal carcinoma and that PLD2 could be a target for therapy in colorectal carcinoma.