Carcinogenesis Advance Access published online on October 13, 2009
Carcinogenesis, doi:10.1093/carcin/bgp244
Vascular endothelial growth factor-c (VEGF-C) promotes angiogenesis by induction of COX-2 in leukemic cells via the VEGF-R3/JNK/AP-1 pathway
1 Laboratory of Molecular and Cellular Toxicology, Institute of Toxicology, College of Medicine and Angiogenesis Research Center, National Taiwan University, Taipei 100, Taiwan
2 Taipei Medical University-Wang-Fang Hospital, Taipei 116, Taiwan
3 The Genomics Research Center, Academia Sinica; Taipei 115, Taiwan
4 Graduate Institute of Cancer Biology, College of Medicine, China Medical University, Taichung 404, Taiwan
5 Department of Food Science and Nutrition, Nara Women's University, Nara, Japan
6 Department of Oncology, National Taiwan University Hospital, Taipei 100, Taiwan
* Correspondence to: Min-Liang Kuo, PhD, Institute of Toxicology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Ren-Ai Road, Taipei 10016, Taiwan; Phone: 886-2-23123456, ext. 88607; Fax: 886-2-23410217; E-mail: kuominliang{at}ntu.edu.tw or Lin-Hung Wei, MD, PhD, Department of Oncology, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan; Phone:886-2-23123456, ext. 67140; Fax: 886-2-23711174; E-mail: weilh1966{at}gmail.com
Vascular endothelial growth factor (VEGF)-C is recognized as a tumor lymphangiogenic factor based on the effects of activated VEGF-R3 on lymphatic endothelial cells. Many tumor cells express VEGF-R3, but the function of this receptor in tumor cells is largely unknown. It has been reported that the VEGF-C/VEGF-R3 axis is activated in subsets of leukemia patients. Herein we have shown that VEGF-C induces angiogenic activity in the tube formation assay in vitro and Matrigel plug assay in vivo by up-regulating an angiogenic factor, cyclooxygenase-2 (COX-2), through VEGF-R3 in the human acute myeloid leukemia (AML) cell line, THP-1. COX-2 induction by VEGF-C was also observed in other VEGF-R3+ human AML cell lines (U937 and HL60). Moreover, immunohistochemical analysis of bone marrow specimens of 37 patients diagnosed with AML revealed that VEGF-C expression in specimens was associated with the expression of COX-2 (P < 0.001). The manner by which signaling pathways transduced by VEGF-C is responsible for COX-2 up-regulation was further investigated. Blocking the p42/44 MAPK pathway with the MEK inhibitor, PD98059, failed to inhibit VEGF-C-mediated COX-2 expression. However, VEGF-C-induced COX-2 up-regulation was effectively abolished by overexpression of dominant-negative (dn) JNK or treatment with the JNK inhibitor, SP600125. VEGF-C induced JNK-dependent nuclear translocation of c-Jun. Furthermore, chromatin immunoprecipitation and reporter assays revealed that VEGF-C enhanced c-Jun binding to the cyclic AMP–response element (CRE) of the COX-2 promoter and induced COX-2 expression. In sum, the data herein highlight the pathogenic role of VEGF-C in leukemia via regulation of angiogenesis through up-regulation of COX-2.
Key Words: VEGF-C • angiogenesis • COX-2
Received July 13, 2009; revised September 18, 2009; accepted October 3, 2009.