Cyclooxygenase-2 induces EP1- and HER-2/Neu-dependent vascular endothelial growth factor-C up-regulation: a novel mechanism of lymphangiogenesis in lung adenocarcinoma.
Cyclooxygenase (COX)-2, the inducible isoform of prostaglandin H synthase, has been implicated in the progression of human lung adenocarcinoma. However, the mechanism underlying COX-2's effect on tumor progression remains largely unknown. Lymphangiogenesis, the formation of new lymphatic vessels, has recently received considerable attention and become a new frontier of tumor metastasis research. Here, we study the interaction between COX-2 and the lymphangiogenic factor, vascular endothelial growth factor (VEGF)-C, in human lung cancer cells and their implication in patient outcomes. We developed an isopropyl-beta-D-thiogalactopyranoside-inducible COX-2 gene expression system in human lung adenocarcinoma CL1.0 cells. We found that VEGF-C gene expression but not VEGF-D was significantly elevated in cells overexpressing COX-2. COX-2-mediated VEGF-C up-regulation was commonly observed in a broad array of non-small cell lung cancer cell lines. The use of pharmacological inhibitors or activators and genetic inhibition by EP receptor-antisense oligonucleotides revealed that prostaglandin EP(1) receptor but not other prostaglandin receptors is involved in COX-2-mediated VEGF-C up-regulation. At the mechanistic level, we found that COX-2 expression or prostaglandin E(2) (PGE(2)) treatment could activate the HER-2/Neu tyrosine kinase receptor through the EP(1) receptor-dependent pathway and that this activation was essential for VEGF-C induction. The transactivation of HER-2/Neu by PGE(2) was inhibited by way of blocking the Src kinase signaling using the specific Src family inhibitor, PP1, or transfection with the mutant dominant negative src plasmid. Src kinase was involved in not only the HER-2/Neu transactivation but also the following VEGF-C up-regulation by PGE(2) treatment. In addition, immunohistochemical staining of 59 lung adenocarcinoma specimens showed that COX-2 level was highly correlated with VEGF-C, lymphatic vessels density, and other clinicopathological parameters. Taken together, our results provided evidence that COX-2 up-regulated VEGF-C and promotes lymphangiogenesis in human lung adenocarcinoma via the EP(1)/Src/HER-2/Neu signaling pathway.
Su
Jen-Liang
JL
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Shih
Jin-Yuan
JY
Yen
Men-Luh
ML
Jeng
Yung-Ming
YM
Chang
Cheng-Chi
CC
Hsieh
Chang-Yao
CY
Wei
Lin-Hung
LH
Yang
Pan-Chyr
PC
Kuo
Min-Liang
ML
D000230:Adenocarcinoma / Q000473:pathology / Q000503:physiopathology*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D051546:Cyclooxygenase 2; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008175:Lung Neoplasms / Q000473:pathology / Q000503:physiopathology*; D042583:Lymphangiogenesis / Q000502:physiology*; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D018078:Receptors, Prostaglandin E / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000502:physiology; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D013873:Thionucleotides / Q000494:pharmacology; D013997:Time Factors; D015533:Transcriptional Activation; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics*
D051546:Cyclooxygenase 2; D007527:Isoenzymes; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D011451:Prostaglandin-Endoperoxide Synthases; D018719:Erb-b2 Receptor Tyrosine Kinases; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; D013873:Thionucleotides; D042582:Vascular Endothelial Growth Factor C; C545635:PTGER1 protein, human; C545647:PTGER3 protein, human; C545650:PTGER4 protein, human; C496540:PTGS2 protein, human