1. ¹Department of Dermatology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
2. ²Laboratory of Molecular and Cellular Toxicology, Institute of Toxicology, National Taiwan University College of Medicine, Taipei, Taiwan
3. ³Department of Dermatology, National Taiwan University College of Medicine, Taipei, Taiwan

Correspondence: Dr Shiou-Hwa Jee, Department of Dermatology, National Taiwan University Hospital and College of Medicine, National Taiwan University, 7, Chung-Shan South Road, Taipei, Taiwan. E-mail: shiouhwa@ha.mc.ntu.edu.tw

⁴These authors contributed equally to this work

Received 16 November 2005; Revised 16 November 2005; Accepted 11 December 2005; Published online 9 March 2006.

Abstract

Cyclooxygenase-2 (COX-2) is critical for tumor formation, angiogenesis, metastasis, and prognosis. In this study, the role of COX-2 in antiapoptosis, tumorigenesis, and angiogenesis of human basal cell carcinoma (BCC) cells was investigated. Transfection of COX-2 constitutive expression vector into a BCC cell line yielded several overexpressing clones. All transfectants demonstrated remarkable resistance to ultraviolet B-induced apoptosis (confirmed by flow cytometry analysis, morphological change, and DNA fragmentation). Immunoblot analysis revealed marked increases in apoptosis-regulated genes Mcl-1 and Bcl-2. A 10-fold concentrated conditioned medium from COX-2-overexpressing BCC cells exhibited higher angiogenic activity in Matrigel plug and human umbilical vein endothelial cell tube formation assay. Cells exhibited increased levels of vascular endothelial growth factor-A (VEGF-A) mRNA and protein, and secreted VEGF-A and basic fibroblast growth factor (bFGF). COX-2-specific small interfering RNA markedly reduced the secreted species. After 7 weeks of inoculation, the tumor volume of COX-2-overexpressing cells in severe combined immunodeficient mice was significantly greater than that of vector control cells. Immunohistochemical analysis of CD31-positive vessels revealed a two-fold increase in microvessel density in COX-2 tumors, compared to control vector tumors. Our data indicate that Mcl-1 and Bcl-2, as well as VEGF-A and bFGF, are downstream effectors of COX-2-induced antiapoptosis and angiogenesis, respectively.