PKCdelta mediates anti-proliferative, pro-apoptic effects of testosterone on coronary smooth muscle.
Sex hormone status has emerged as an important modulator of coronary physiology and cardiovascular disease risk in both males and females. Our previous studies have demonstrated that testosterone increases protein kinase C (PKC) delta expression and activity in coronary smooth muscle (CSMC). Because PKCdelta has been implicated in regulation of proliferation and apoptosis in other cell types, we sought to determine if testosterone modulates CSMC proliferation and/or apoptosis through PKCdelta. Porcine CSMC cultures (passages 2-6) from castrated males were treated with testosterone for 24 h. Testosterone (20 and 100 nM) decreased [(3)H]thymidine incorporation in proliferating CSMC to 59 +/- 5.3 and 33.1 +/- 4.5% of control. Flow cytometric analysis demonstrated that testosterone induced G(1) arrest in CSMC with a concomitant reduction in the S phase cells. Testosterone reduced protein levels of cyclins D(1) and E and phosphorylation of retinoblastoma protein while elevating levels of p21(cip1) and p27(kip1). There were no significant differences in the levels of cyclins D(3), CDK2, CDK4, or CDK6. Testosterone significantly reduced kinase activity of CDK2 and -6, but not CDK4, -7, or -1. PKCdelta small interfering RNA (siRNA) prevented testosterone-mediated G(1) arrest, p21(cip1) upregulation, and cyclin D(1) and E downregulation. Furthermore, testosterone increased CSMC apoptosis in a dose-dependent manner, which was blocked by either PKCdelta siRNA or caspase 3 inhibition. These findings demonstrate that the anti-proliferative, pro-apoptotic effects of testosterone on CSMCs are substantially mediated by PKCdelta.
Bowles
D K
DK
Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA. BowlesD@missouri.edu
Maddali
K K
KK
Dhulipala
V C
VC
Korzick
D H
DH
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002369:Castration; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D051745:Protein Kinase C-delta / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016196:S Phase / Q000187:drug effects; D013552:Swine; D013739:Testosterone / Q000378:metabolism* / Q000494:pharmacology
D061945:Caspase Inhibitors; D016213:Cyclins; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D013739:Testosterone; D051745:Protein Kinase C-delta; D018844:Cyclin-Dependent Kinases; D053148:Caspase 3