Vascular endothelial growth factor receptor 2 (VEGFR-2) mediates angiogenesis and neovascularization induced by VEGF and this study investigates the molecular mechanism of regulation of VEGFR-2 in human pancreatic cancer cells. Analysis of the VEGFR-2 gene promoter was investigated in pancreatic cells transfected with a series of constructs containing -716 to +268 (pVEGFR-A), -225 to +268 (pVEGFR-B), -95 to +268 (pVEGFR-C), -77 to +268 (pVEGFR-D), and -60 to +268 (pVEGFR-E), VEGFR-2 promoter inserts. Basal luciferase activity in MiaPaCa-2 pancreatic cancer cells was not significantly different after transfection of pVEGFR-A, pVEGFR-B, pVEGFR-C, pVEGFR-D, or pVEGFR-E. In contrast, transfection of Panc-1 and AsPC-1 cells with the same constructs indicated that deletion of the -77 to -60 region resulted in a 30-40% loss of activity suggesting that the GC-rich Sp binding site in this region of the promoter was important for regulation of VEGFR-2 in these cell lines. MiaPaCa-2, Panc-1, and AsPC-1 cells transfected with pVEGFR-F (-37 to +268) and mutation analysis of the -60 to -37 region of the promoter demonstrated the importance of two additional proximal GC-rich sites in regulation of VEGFR-2 in all three pancreatic cancer cells. Basal luciferase activity decreased approximately 65-85% in Panc-1, AsPC-1, and MiaPaCa-2 cells transfected with pVEGFR-F or mutated pVEGFR-E. These results demonstrate that VEGFR-2 regulation in pancreatic cancer cells is dependent on Sp protein interactions with proximal GC promoter sequences, and similar patterns of regulation of VEGF by Sp proteins has also been observed. Current studies using RNA interference for Sp proteins are investigating the role of Sp1, Sp2, Sp3, and Sp4 in regulating VEGFR-2 gene/reporter gene and protein expression in pancreatic cancer cells (Supported by the pancreatic cancer SPORE grant to M.D. Anderson Cancer Center P20 CA10193).
[Proc Amer Assoc Cancer Res, Volume 46, 2005]