title: Effects of COX-2 inhibition on expression of vascular endothelial growth factor and interleukin-8 in lung cancer cells.
abstract: BACKGROUND
  Cyclooxygenase (COX)-2 has been implicated in tumour progression, angiogenesis and metastasis in non-small cell lung cancer (NSCLC). We speculated that inhibition of COX-2 activity might reduce expression of the pro-angiogenic factors vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) in lung cancer cells.
  
  
  METHODS
  The levels of IL-8, VEGF and prostaglandin E2 (PGE2) were measured by ELISA. Expression of COX-1 and COX-2 was determined by Western blotting. Inhibition or knockdown of COX-2 was achieved by treating NSCLC cells with specific COX-2 inhibitor NS-398 or COX-2 siRNA, respectively.
  
  
  RESULTS
  We found that NSCLC cell lines produced more IL-8 than VEGF (p < 0.001). In contrast, small cell lung cancer (SCLC) cell lines produced more VEGF than IL-8 (p < 0.001). COX-1 was expressed in all cell lines, but COX-2 was expressed only in NSCLC cell lines. Consistent with this, PGE2 was significantly higher in NSCLC cell lines than SCLC cell lines (p < 0.001). We tested these cell lines with a potent specific COX-2 inhibitor NS-398 at concentrations of 0.02, 0.2, 2, 20 microM for 24 or 48 h. The COX-2 activity was reduced in a dose-dependent fashion as shown by reduced PGE2 production. VEGF was significantly reduced following the treatment of NS-398 in A549 (by 31%) and MOR/P (by 47%) cells lines which expressing strong COX-2, but not in H460 cell line which expressing very low COX-2. However, IL-8 was not reduced in these cell lines. To confirm these results, we knocked down COX-2 expression with COX-2 siRNA in these cell lines. VEGF was significantly decreased in A549 (by 24%) and in MOR/P (by 53%), but not in H460 whereas IL-8 was not affected in any cell line.
  
  
  CONCLUSIONS
  We conclude that NSCLC cells produce much higher levels of IL-8 than SCLC cells whereas both NSCLC and SCLC cells produce similar levels of VEGF. COX-2 is only expressed in NSCLC cells, but not in SCLC cells. VEGF is produced in both NSCLC and SCLC cells regardless of COX-2 expression. However, VEGF production is, at least partly, COX-2 dependent in NSCLC cells expressing COX-2. In contrast, IL-8 production is COX-2 independent in both NSCLC and SCLC cells. We speculate that combined targeting of COX-2 and IL-8 may be useful in the treatment of patients with NSCLC and targeting VEGF may be useful in the treatment of patients with SCLC.
authors.affiliation: Institute for Cancer Studies, School of Medicine and Biomedical Science, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK. y.m.zhu@sheffield.ac.uk
authors.forename: Yong Ming
authors.initials: YM
authors.lastname: Zhu
authors.forename: Nor Saadah M
authors.initials: NS
authors.lastname: Azahri
authors.forename: Danny C W
authors.initials: DC
authors.lastname: Yu
authors.forename: Penella J
authors.initials: PJ
authors.lastname: Woll
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism*; D018288:Carcinoma, Small Cell / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051546:Cyclooxygenase 2 / Q000502:physiology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism*; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D016861:Cyclooxygenase Inhibitors; D016209:Interleukin-8; D042461:Vascular Endothelial Growth Factor A; D051546:Cyclooxygenase 2; D015232:Dinoprostone