Autocrine vascular endothelial growth factor/vascular endothelial growth factor receptor-2 growth pathway represents a cyclooxygenase-2-independent target for the cyclooxygenase-2 inhibitor NS-398 in colon cancer cells.
OBJECTIVE
Coexpression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2) has been reported in tumor cells, suggesting the presence of an autocrine VEGF/VEGFR-2 growth pathway in solid tumors. Thus, we hypothesize that the presence of this autocrine pathway in colon cancer cells may be a COX-2-independent target of COX-2 inhibitors and a mechanism behind the antitumor effects of these agents.


METHODS
COX-2-positive (Caco2, HT-29) and COX-2-negative colon cancer cells (DLD-1, Hct-15) were used. Expression of VEGFR-2 was evaluated by Western blot and reverse transcriptase-polymerase chain reaction and VEGF production was measured from culture supernatant by enzyme-linked immunosorbent assay. Growth inhibition and the expression of VEGF and VEGFR-2 were compared after treatment with the COX-2 inhibitor, NS-398 at doses ranging from 5 to 100 microM.


RESULTS
VEGF and VEGFR-2 were expressed in all four colon cancer cells and a blockade of VEGFR-2 with anti-VEGFR-2 antibody treatment induced growth inhibition of colon cancer cells, supporting the presence of autocrine VEGF/VEGFR-2 growth pathway. NS-398 suppressed the growth of colon cancer cells, independent of COX-2 expression. VEGFR-2 expression of tumor cells was reduced after NS-398 treatment at 100 microM, the concentration at which maximal growth inhibition was induced. The amount of VEGF in culture supernatant was increased by NS-398 at 100 microM, suggesting increased secretion of VEGF in compensation for reduced VEGFR-2 expression.


CONCLUSIONS
The autocrine VEGF/VEGFR-2 growth pathway could be a COX-2-independent target of the COX-2 inhibitor, NS-398, in colon cancer cells.
Kim
Seok Jin
SJ
Division of Oncology and Hematology, Department of Internal Medicine, College of Medicine, Korea University, Kozan-1 Dong, Ansan City, Kyoung-ki, Seoul, Korea.
Seo
Jae Hong
JH
Lee
Yoo Jung
YJ
Yoon
Ji Hye
JH
Choi
Chul Won
CW
Kim
Byung Soo
BS
Shin
Sang Won
SW
Kim
Yeul Hong
YH
Kim
Jun Suk
JS
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D018938:Caco-2 Cells; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects* / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000187:drug effects* / Q000378:metabolism
D000970:Antineoplastic Agents; D016861:Cyclooxygenase Inhibitors; D009578:Nitrobenzenes; D013449:Sulfonamides; D042461:Vascular Endothelial Growth Factor A; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D040301:Vascular Endothelial Growth Factor Receptor-2