Aberrant expression of COX-2 occurs in many types of malignancies including 
colon and lung cancers, and is implicated in development and progression of 
cancer. The molecular mechanisms associated with aberrant expression of COX-2 in 
lung cancer cells remain to be fully elucidated. In this study, we found that 
non-small cell lung cancer (NSCLC) NCI-H520 and NCI-H460 cells constitutively 
expressed COX-2 and produced prostaglandin E2 (PGE2) as measured by Western 
blotting and enzyme-linked immunosorbent assay (ELISA), respectively. Reporter 
assays showed that transcriptional regulation of COX-2 was blunted when either 
the NF-IL6 (C/EBPbeta) or nuclear factor-kappaB (NF-kappaB) binding site in the 
COX-2 promoter was mutated, suggesting that C/EBPbeta and NF-kappaB 
transcription factors have an important role in aberrant expression of COX-2 in 
these lung cancer cells. In addition, the eight herbal mixture PC-SPES (Lot. 
5431219) caused growth arrest and apoptosis of NCI-H520 and NCI-H460 cells in 
association with blockade of NF-kappaB and down-regulation of C/EBPbeta, 
resulting in down-regulation of COX-2 and PGE2 in these cells. On the other 
hand, PC-SPES up-regulated the level of C/EBPbeta in these cells. Taken 
together, C/EBPbeta and NF-kappaB may be promising molecular targets for COX-2 
inhibition in lung cancer cells. PC-SPES might be useful in the adjuvant setting 
for the treatment of individuals with resected NSCLC as well as other types of 
cancer in which COX-2 is activated.