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Human placental development is characterized by invasion of extravillous cytotrophoblasts (EVCTs) into the uterine wall during the first trimester of pregnancy. Peroxisome proliferator-activated receptor γ (PPARγ) plays a major role in placental development, and activation of PPARγ by its agonists results in inhibition of EVCT invasion in vitro. To identify PPARγ target genes, microarray analysis was performed using GeneChip technology on EVCT primary cultures obtained from first-trimester human placentas. Gene expression was compared in EVCTs treated with the PPARγ agonist rosiglitazone versus control. A total of 139 differentially regulated genes were identified, and changes in the expression of the following 8 genes were confirmed by reverse transcription-quantitative polymerase chain reaction: a disintegrin and metalloproteinase domain12 (ADAM12), connexin 43 (CX43), deleted in liver cancer 1 (DLC1), dipeptidyl peptidase 4 (DPP4), heme oxygenase 1 (HMOX-1), lysyl oxidase (LOX), plasminogen activator inhibitor 1 (PAI-1) and PPARγ. Among the upregulated genes, lysyl oxidase (LOX) was further analyzed. In the LOX family, only LOX, LOXL1 and LOXL2 mRNA expression was significantly upregulated in rosiglitazone-treated EVCTs. RNA and protein expression of the subfamily members LOX, LOXL1 and LOXL2 were analyzed by absolute RT-qPCR and western blotting, and localized by immunohistochemistry and immunofluorescence-confocal microscopy. LOX protein was immunodetected in the EVCT cytoplasm, while LOXL1 was found in the nucleus and nucleolus. No signal was detected for LOXL2 protein. Specific inhibition of LOX activity by β-aminopropionitrile in cell invasion assays led to an increase in EVCT invasiveness. These results suggest that LOX, LOXL1 and LOXL2 are downstream PPARγ targets and that LOX activity is a negative regulator of trophoblastic cell invasion.

Background:Medullary thyroid carcinoma (MTC) is a C cell neoplasm secreting calcitonin (CT). Surgery remains the only treatment as MTC is resistant to radio- and chemotherapies. Anti-tumoral effects of nonsteroidal anti-inflammatory drugs have been observed in various cancers. Thus, we tested the anti-tumoral action of an nonsteroidal anti-inflammatory drug, celecoxib, on MTC development.Methods:We studied the expression of prostaglandin (PG) metabolism enzymes in our in vitro(TT cells) and in vivo(TT tumors) models and in human MTCs by Western blot. We checked the effect of celecoxib on xenografted subcutaneous tumors in nude mice. Celecoxib was administrated in powder food during 9 weeks from day 1 after TT cell injection. At the end of the experiment plasma CT was measured by radioimmunoassay, the number of proliferating cells in tumor tissues was detected by Ki67 immunocytochemistry and apoptotic nuclei by caspase 3 ad Bcl-2 expression and terminal-deoxynucleotidyl-transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. PGE2concentrations in TT cell medium were evaluated by an enzyme immunoassay kit.Results:Our in vitroand in vivomodels were validated: the status of PG metabolism enzymes was comparable in these models and in human MTCs. A very low dose of celecoxib, 120 ppm in food, inhibited tumor volume by 71% and reduced plasma CT level. Although no proapoptotic effect was detectable in tumors, a decrease of proliferating cells was revealed. The inducible PG synthesis enzyme, cyclooxygenase 2, was only detectable in rare stromal cells. The expression of the constitutive PG synthesis enzyme, cyclooxygenase 1, was diminished, while the level of the catabolism enzyme, 15-PG dehydrogenase, was decreased. In vitro, TT cells treated for 12 days with 25 μM celecoxib reproduced these changes, and PGE2secretion was not significantly modified by the treatment, in these conditions.Conclusion:Celecoxib has a good therapeutic potential for MTC to prevent metastasis growth, and its anti-tumoral effect is, at least in part, independent of PGE2. [ABSTRACT FROM AUTHOR]