Cyclooxygenase-2–Dependent Expression of Survivin in Non-small Cell Lung Cancer

Abstract

Cyclooxygenase-2 (COX-2) overexpression is found in a wide variety of human cancers, including lung cancer. 1 Dannenberg AJ Subbaramaiah K Targeting cyclooxygenase-2 in human neoplasia: rationale and promise. Cancer Cell. 2003; 4: 431-436 Abstract Full Text Full Text PDF PubMed Scopus (429) Google Scholar 2 Dubinett SM Sharma S Huang M et al. Cyclooxygenase-2 in lung cancer. Prog Exp Tumor Res. 2003; 37: 138-162 Crossref PubMed Scopus (43) Google Scholar Elevated tumor COX-2 expression is associated with increased angiogenesis, 3 Pold M Zhu LX Sharma S et al. Cyclooxygenase-2-dependent expression of angioenic CXC chemokines ENA-78/CXC Ligand (CXCL) 5 and interleukin-8/CXCL8 in human non-small cell lung cancer. Cancer Res. 2004; 64: 1853-1860 Crossref PubMed Scopus (109) Google Scholar tumor invasion, 4 Dohadwala M Luo J Zhu L et al. Non-small cell lung cancer cyclooxygenase-2-dependent invasion is mediated by CD44. J Biol Chem. 2001; 276: 20809-20812 Crossref PubMed Scopus (219) Google Scholar 5 Dohadwala M Batra RK Luo J et al. Autocrine/paracrine prostaglandin E2 production by non-small cell lung cancer cells regulates matrix metalloproteinase-2 and CD44 in cyclooxygenase-2-dependent invasion. J Biol Chem. 2002; 277: 50828-50833 Crossref PubMed Scopus (244) Google Scholar 6 Tsujii M DuBois RN Alterations in cellular adhesion and apoptosis in epithelial cells overexpressing prostaglandin endoperoxide synthase 2. Cell. 1995; 83: 493-501 Abstract Full Text PDF PubMed Scopus (2131) Google Scholar suppression of host immunity, 7 Stolina M Sharma S Lin Y et al. Specific inhibition of cyclooxygenase 2 restores antitumor reactivity by altering the balance of IL-10 and IL-12 synthesis. J Immunol. 2000; 164: 361-370 Crossref PubMed Scopus (455) Google Scholar 8 Huang M Stolina M Sharma S et al. Non-small cell lung cancer cyclooxygenase-2-dependent regulation of cytokine balance in lymphocytes and macrophages: up-regulation of interleukin 10 and down-regulation of interleukin 12 production. Cancer Res. 1998; 58: 1208-1216 PubMed Google Scholar and promotion of tumor cell resistance to apoptosis. 9 Krysan K Merchant FH Zhu L et al. COX-2-dependent stabilization of survivin in non-small cell lung cancer. FASEB J. 2004; 18: 206-208 Crossref PubMed Scopus (131) Google Scholar To analyze COX-2-dependent gene expression and apoptosis, cell lines constitutively expressing COX-2 complementary DNA in sense and antisense orientations were created by transducing A549 and H157 non-small cell lung cancer (NSCLC) cell lines with retroviral constructs. We find that COX-2 overexpression and its product prostaglandin E2 (PGE2) increase the apoptosis threshold of NSCLC cells and genetic or pharmacologic inhibition of COX-2 sensitizes them to apoptotic signals. The expression of the antiapoptotic protein survivin correlated positively with COX-2 expression in parental, COX-2 sense and antisense cells. Immunohistochemical analysis of human NSCLC resection specimens revealed frequent co-expression of COX-2 and survivin. Survivin ubiquitination was significantly diminished in COX-2 sense and elevated in antisense cells, thus leading to enhanced survivin degradation in COX-2 antisense cells. A similar effect was elicited by exogenous PGE2 treatment of parental NSCLC cells. In contrast to previous studies in other cell types, survivin in NSCLC cells was expressed in a cell cycle-independent manner. Tumor development in SCID mice was assessed by inoculation of equal amounts of control and COX-2 sense or antisense NSCLC cells. Consistent with our in vitro findings, survivin levels were significantly lower in tumors that developed from COX-2 antisense cells and higher in COX-2 sense-derived tumors. Our results support the hypothesis that COX-2 overexpression and PGE2 overproduction inhibit survivin ubiquitination, which leads to its stabilization and prevents proteasomal degradation of survivin in NSCLC cells. Our findings provide evidence for the importance of COX-2 overexpression in the regulation of anti-apoptotic proteins and lung cancer cell survival.