title: Inhibition of cyclooxygenase-2 activity enhances steroidogenesis and steroidogenic acute regulatory gene expression in MA-10 mouse Leydig cells.
abstract: To study the mechanism for the regulatory effect of arachidonic acid (AA) on steroidogenesis, the role of cyclooxygenase (COX) in steroid production and steroidogenic acute regulatory (StAR) gene expression was investigated. Although stimulation with 0.05 mM dibutyryl cAMP (Bt(2)cAMP) did not increase StAR protein or progesterone in MA-10 mouse Leydig cells, the addition of 1 microM of the COX inhibitor indomethacin increased StAR protein expression and progesterone production by 5.7-fold and 34.3-fold, respectively. In the presence of indomethacin, the level of Bt(2)cAMP required for maximal steroidogenesis was reduced from 1.0 mM to 0.25 mM. Similar results were obtained in studies on StAR promoter activity and in Northern blot analyses of StAR mRNA expression, suggesting that inhibition of COX activity enhanced StAR gene transcription. COX2 (an inducible isoform of COX) was constitutively detected in MA-10 cells. Although SC560, a selective COX1 inhibitor, did not affect steroidogenesis, the COX2 inhibitor NS398 significantly enhanced Bt(2)cAMP-stimulated StAR protein expression and steroid production. Overexpression of the COX2 gene in COS-1 cells significantly inhibited StAR promoter activity. The results of the present study suggest that inhibition of COX2 activity increases the sensitivity of steroidogenesis to cAMP stimulation in MA-10 Leydig cells.
authors.affiliation: Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA. xingjia.wang@ttmc.ttuhsc.edu
authors.forename: XingJia
authors.initials: X
authors.lastname: Wang
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Dyson
authors.forename: Youngah
authors.initials: Y
authors.lastname: Jo
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Stocco
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D019556:COS Cells; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis; D015870:Gene Expression / Q000187:drug effects*; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D007984:Leydig Cell Tumor; D007985:Leydig Cells / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics*; D011374:Progesterone / Q000096:biosynthesis; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D010750:Phosphoproteins; D013256:Steroids; D000098682:Steroidogenic Acute Regulatory Protein; D011374:Progesterone; D003994:Bucladesine; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D015232:Dinoprostone; D007213:Indomethacin