15-deoxy-delta(12-14)-prostaglandin-j2 and Lung-Neoplasms

15-Deoxy-Delta-prostaglandin J2 is a naturally occurring endogenous ligand for peroxisome proliferator-activated receptor-gamma. The current study was aimed to determine the mechanism of anti-proliferative effect of 15-deoxy-Delta-prostaglandin J2+docetaxel against A549 and H460 non-small-cell lung cancer cell lines and xenograft tumors. In-vitro cytotoxicity of 15-deoxy-Delta-prostaglandin J2 alone and in combination with docetaxel was studied against A549 and H460 cell lines. For in-vivo studies, female athymic nu/nu mice were xenografted with A549 and H460 tumors and treated with 15-deoxy-Delta-prostaglandin J2 (1 mg/kg/day; intraperitoneal), docetaxel (10 mg/kg; intravenous on days 14, 18 and 22) and 15-deoxy-Delta-prostaglandin J2+docetaxel. Apoptosis was measured in A549 cells and tumor tissues, following various treatments. Peroxisome proliferator-activated receptor-gamma, caspases, Bcl2 and p53 family proteins or their mRNA expressions were measured by Western blotting, reverse transcription-polymerase chain reaction and real-time polymerase chain reaction in A549 tumors. A possible role of a peroxisome proliferator-activated receptor-gamma-independent mechanism was studied in A549 cells treated with peroxisome proliferator-activated receptor-gamma antagonist, GW9662. Isobolographic analysis demonstrated synergistic interaction (combination index <1.0) between 15-deoxy-Delta-prostaglandin J2 and docetaxel against A549 and H460 cells in vitro. 15-Deoxy-Delta-prostaglandin J2+docetaxel significantly reduced the tumor volume compared with control (P<0.05), 15-deoxy-Delta-prostaglandin J2 (P<0.05) and docetaxel (P<0.05, P<0.01) in both A549 and H460 tumors. 15-Deoxy-Delta-prostaglandin J2+docetaxel showed a significant increase in apoptosis associated with inhibition of the Bcl2 and cyclin D1 expression and overexpression of caspase and p53 pathway genes. Further, enhanced expression of caspase 3 and inhibition of cyclin D1 by 15-deoxy-Delta-prostaglandin J2+docetaxel was not reversed by GW9662, thus suggesting a possible peroxisome proliferator-activated receptor-gamma-independent mechanism. In conclusion, 15-deoxy-Delta-prostaglandin J2 enhanced the anti-tumor action of docetaxel by peroxisome proliferator-activated receptor-gamma-dependent and -independent mechanisms mediated by induction of apoptosis.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Non-Small-Cell Lung; Caspase 3; Cell Line, Tumor; Docetaxel; Drug Synergism; Female; Humans; Immunologic Factors; In Situ Nick-End Labeling; Lung Neoplasms; Mice; PPAR gamma; Prostaglandin D2; Reverse Transcriptase Polymerase Chain Reaction; Taxoids; Transplantation, Heterologous

Peroxisome proliferator-activated receptor gamma (PPARgamma) plays a critical albeit poorly defined role in the development and progression of several cancer types including those of the breast, colon, and lung. A PPAR response element (PPRE) reporter assay was utilized to evaluate the selective transactivation of PPARgamma in 10 different cell lines including normal mammary epithelial, breast, lung, and colon cancer cells. Cells were treated with one of four compounds including rosglitizone (Ros), ciglitizone (Cig), 15-deoxy-Delta(12,14)-prostaglandin J2 (PGJ2), or GW 9662 (GW). We observed differences in transactivation between cell lines from different tissue origin, across cell lines from a single tissue type, and selective modulation of PPARgamma within a single cell line by different ligands. Interestingly, GW, a PPARgamma antagonist in adipocytes, enhanced PPRE reporter activation in normal mammary epithelial cells while it had virtually no effect in any of the cancer cell lines tested. Within each cancer type, individual cell lines were found to respond differently to distinct PPARgamma ligands. For instance, Ros, Cig, and PGJ2 were all potent agonist of PPARgamma transactivation in lung adenocarcinoma cell lines while these same ligands had no effect in squamous cell or large cell carcinomas of the lung. Message levels of PPARgamma and retinoid X receptor alpha (RXRalpha) in the individual cell lines were quantitated by real time-polymerase chain reaction (RT-PCR). The ratio of PPARgamma to RXRalpha was predictive of how cells responded to co-treatment of Ros and 9-cis-retinoic acid, an RXRalpha agonist, in two out of three cell lines tested. These data indicate that PPARgamma can be selectively modulated and suggests that it may be used as a therapeutic target for individual tumors.

Topics: Alitretinoin; Anilides; Breast Neoplasms; Caco-2 Cells; Cell Line, Tumor; Colonic Neoplasms; Female; Gene Expression Regulation, Neoplastic; Genes, Reporter; HT29 Cells; Humans; Ligands; Lung Neoplasms; PPAR gamma; Prostaglandin D2; Retinoid X Receptor alpha; RNA, Messenger; Rosiglitazone; Thiazolidinediones; Transfection; Tretinoin

Peroxisome proliferator-activated receptors (PPARs), members of the nuclear hormone receptors superfamily, have an important regulatory role in adipogenesis and inflammation. PPAR-gamma ligands induce terminal differentiation and growth inhibition of human breast cancer cells and prostatic cancer cells. In this study, we demonstrated that PPAR-gamma, but not PPAR-alpha, was expressed in human lung cancer cell lines by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. We also found that the synthetic PPAR-gamma agonist thiazolidinedione compounds (troglitazone) and the endogenous PPAR-gamma ligand, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), inhibited the growth of human lung cancer cells through the induction of apoptosis. However, PPAR-alpha agonist (bezafibrate) and other prostanoids (PGE(2), PGF(2alpha)) did not induce apoptosis. These findings suggest that PPAR-gamma may play an important role in the pathogenesis of lung cancer and that PPAR-gamma agonist may be useful therapeutic agents in the treatment of human lung cancer.

Topics: Apoptosis; Base Sequence; Cell Division; Chromans; DNA Primers; Humans; Lung Neoplasms; Prostaglandin D2; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Thiazoles; Thiazolidinediones; Transcription Factors; Troglitazone; Tumor Cells, Cultured