Inhibition of testicular embryonal carcinoma cell tumorigenicity by peroxisome proliferator-activated receptor-β/δ- and retinoic acid receptor-dependent mechanisms

Abstract

Peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) has important physiological functions in control of cell growth, lipid and glucose homeostasis, differentiation and inflammation. To investigate the role of PPARβ/δ in cancer, stable human testicular embryonal carcinoma cell lines were developed that constitutively express PPARβ/δ. Expression of PPARβ/δ caused enhanced activation of the receptor, and this significantly decreased proliferation, migration, invasion, anchorage-independent growth, and also reduced tumor mass and volume of ectopic xenografts derived from NT2/D1 cells compared to controls. The changes observed in xenografts were associated with decreased PPARβ/δ-dependent expression of proliferating cell nuclear antigen and octamer-binding transcription factor-3/4, suggesting suppressed tumor proliferation and induction of differentiation. Inhibition of migration and invasion was mediated by PPARβ/δ competing with formation of the retinoic acid receptor (RAR)/retinoid X receptor (RXR) complex, resulting in attenuation of RARα-dependent matrix metalloproteinase-2 expression and activity. These results demonstrate that PPARβ/δ mediates attenuation of human testicular embryonal carcinoma cell progression through a novel RAR-dependent mechanism and suggest that activation of PPARβ/δ inhibits RAR/RXR dimerization and represents a new therapeutic strategy.

Peroxisome proliferator‐activated receptor‐β/δ modulates mast cell phenotype

“…Interestingly, no significant differences in apoptosis of BMMCs from Pparβ/δ +/+ or Pparβ/δ −/− mice were observed. To date, whether PPAR β / δ is pro‐apoptotic or anti‐apoptotic remains controversial (reviewed in refs ); however, results from the present study support previous work showing that PPAR β / δ has no direct effect on apoptosis …”

“…Quantitative Western blot analysis using a radioactive detection method was performed as previously described. 19 To analyse the expression of phosphoproteins, BMMCs (2 9 10 6 ) were homogenized in RIPA buffer supplemented with a protease inhibitor cocktail, 5Á4 mM sodium pyrophosphate, 50 mM sodium fluoride and 1 mM sodium orthovanadate (Sigma-Aldrich). Membranes were blocked with either 5% non-fat milk or phosphoprotein blocker (Millipore, Billerica, MA).…”

“…Expression of mast cell mediator genes in BMMCs in response to DNP-HSA, UVB, LPS and TPA treatment was determined by quantitative PCR analysis as previously described. 19 Mast cell mediator genes included carboxypeptidase A3 (Cpa3), b-hexosaminidase A (Hexa), b-hexosaminidase B (Hexb), mast cell protease 4 (Mcpt4), chymase 1 (Cma1, also known as Mcpt5), tryptase b-2 (Tpsb2, also known as Mcpt6), Il6, Il10, tumour necrosis factor-a (Tnfa) and vascular endothelial growth factor (Vegf). Each assay included a standard curve and a non-template control that were performed in triplicate.…”

Regulation of Cytochrome P450 2B10 (CYP2B10) Expression in Liver by Peroxisome Proliferator-activated Receptor-β/δ Modulation of SP1 Promoter Occupancy

“…Quantitative Real Time Polymerase Chain Reaction (qPCR)-Expression of mouse Cyp2b10, Cyp3a11, and Angptl4 in response to ethanol treatment was determined by qPCR analysis as previously described (38). Briefly, total RNA was isolated using RiboZol RNA extraction reagent (AMRESCO, Solon, OH) following the manufacturer's recommended procedures.…”

“…ChIP-qPCR-To confirm the occupancy of SP1 on the Cyp2b10 promoter, ChIP-qPCR was performed to quantify relative promoter occupancy following ethanol exposure in primary hepatocytes from Ppar␤/␦ ϩ/ϩ and Ppar␤/␦ Ϫ/Ϫ mice as previously described (38). The following primary antibody was used: anti-SP1 (sc59, lot no.…”