Novel expression of vascular endothelial growth factor isoforms in the pancreas and pancreatic cystic lesions

Abstract

Vascular endothelial growth factor (VEGF)-A is known to play key biological roles in angiogenesis and vascular permeability. We previously identified VEGF-A as an accurate biomarker of benign pancreatic cystic lesions known as serous cystic neoplasms (SCN). In the present study, we seek to further characterize the expression of VEGF-A and its splice isoforms in different pancreatic cysts including SCN. Patients undergoing surgery were consented for the collection of pancreatic cystic lesion tissue (SCN, pseudocysts, mucinous cysts) and normal adjacent pancreas as well as pancreatic cyst fluid. Following RNA isolation from the tissues, relative VEGF-A gene expression was quantitatively analyzed using real-time PCR (qPCR), and VEGF-A isoform expression was evaluated by reverse transcriptase (RT)-PCR. Relative VEGF-A gene expression was significantly increased in SCN, demonstrating transcriptional upregulation in SCN compared to other pancreatic cyst tissues (P < 0.0001). VEGF-189, -165, −145, and −121 splice variants were detected in both normal adjacent pancreas and pancreatic cystic lesions; the novel VEGF-111 isoform was variably expressed in normal and cyst tissues. Finally, VEGF isoform levels in pancreatic cyst fluid were measured by isoform-specific ELISAs. VEGF-165, -145, and −121 proteins were present in pancreatic cyst fluids; VEGF-165 levels were significantly higher in SCN cyst fluid. Thus, multiple VEGF isoforms were expressed in normal pancreas and pancreatic cysts. Of particular interest are VEGF-145 and -111, which have not previously been described in human pancreas where they may exhibit unique biological activities in health and/or disease.