Data was expressed as mean SEM of 4 indie experiments. Figure 2 shows the tumor volume-time data profiles after the administration of vehicle control, celecoxib, docetaxel and the combination of celecoxib with docetaxel in mice xenografted with A549 tumors. combination group as compared to the celecoxib- or docetaxel-treated groups and this was associated with an increase in the intratumor p53 expression. In conclusion, the combination of celecoxib with docetaxel produces a greater antitumor effect in s.c. A549 tumors as compared to celecoxib or docetaxel alone and this effect is associated with concomitant alterations in the intratumor levels of PGE2 and 15-d PGJ2. antiproliferative effect of celecoxib has been attributed to the induction of apoptosis.8 Docetaxel has been approved for the treatment of NSCLC patients and exhibits its cytotoxic effect due to decreased proliferation and induction of apoptosis by stabilization of microtubules. Thus, the combination of celecoxib with docetaxel might be beneficial and currently clinical trials are underway in NSCLC patients.9,10 The recent Phase II clinical data suggest that the combination of docetaxel and celecoxib can be safely given in NSCLC patients.11 The molecular mechanisms responsible for the antitumor effect of celecoxib alone and in combination with anticancer drugs have not been clearly elucidated yet. It has been reported that celecoxib decreases the intratumor prostaglandin E2 (PGE2) levels in head and neck xenograft tumors without affecting the COX-2 expression.12 The reduction of intratumor PGE2 levels has been thought to be mediated enzymatic inhibition of COX-2 activity in the tumor milieu by celecoxib. Recent evidence also indicates that increased prostaglandin biosynthesis is usually associated with the expression and activity of cytoplasmic phospholipase A2 (cPLA2, an enzyme involved in the release of arachidonic acid from membrane lipids) and COX-2 in A549 cells.13 Further, COX-2 and microsomal prostaglandin E 5(6)-FITC synthase (mPGES, an enzyme mediating the conversion of prostaglandin H2 to PGE2 and functionally 5(6)-FITC linked to COX-2) have been shown to be overexpressed in lung malignancy patients.14 In addition, other COX independent mechanisms have also been reported for selective COX-2 inhibitors.15,16 We have reported recently that increased expression of peroxisome proliferator activated receptor- (PPAR-) was associated 5(6)-FITC with the cytotoxicity enhancement of doxorubicin by a selective COX-2 inhibitor nimesulide in human lung adenocarcinoma, A549 cells and the antitumor effect of nimesulide in s.c. A549 5(6)-FITC tumor xenografts.17,18 In the light of these studies, we hypothesize that this antitumor effect of celecoxib or its combination with docetaxel may be associated with reduced intratumor PGE2 levels along with alterations in the expression of key targets involved in the PGE2 biosynthesis such as cPLA2 and mPGE synthase. We also hypothesize that this combination of celecoxib with docetaxel may increase the expression of PPAR-17C19 and alter the 5(6)-FITC 15-deoxy prostaglandin J2 (15-d PGJ2) levels.20 The objectives of our present investigation were to study: (in human lung adenocarcinoma, A549 cells as well as its xenograft tumors in nude mice, (synthase and primer pairs and ATAQ DNA polymerase (Applied Biosystem) for 30 cycles of 94C, 52C, (60 C for mPGES) and 72C (1 min each), and then 10 min at 72 C before holding at 4C. The PCR products (COX-2, 226 bp; PPAR-, 360 bp; VEGF, 121 bp; mPGES, 459 bp and -actin 390 bp) were separated in a 1.5% agarose gel and the band intensities were normalized with respect to -actin using Scion Image Software (Beta 3b version, Scion Corporation, Frederick, MD). Statistical Mouse monoclonal to CD40 analysis Differences in tumor volume between treatment groups were analyzed using non-parametric Mann-Whitney test18 and the significance of the difference in the expression of PPAR-, cPLA2, p53, VEGF and the prostaglandin levels (PGE2 and 15-d PGJ2), among the different treatments was analyzed by one-way ANOVA followed by Tukeys multiple comparison.