PKCδ mediates anti-proliferative, pro-apoptic effects of testosterone on coronary smooth muscle

Abstract

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.

Testosterone induces apoptosis in vascular smooth muscle cells via extrinsic apoptotic pathway with mitochondria-generated reactive oxygen species involvement

“…In agreement with our results, Bowles et al (5) showed that in VSMCs isolated from pig coronaries, testosterone treatment increases approximately fourfold caspase-3 activity, an effect inhibited by PKC-␦ small interfering RNA. Decreased expression of TNF-␣, IL-1␤, IL-6, p38 MAPK, caspase 1, 3, and 11 and increased expression of the antiapoptotic protein Bcl-2 have been reported in castrated and flutamide-treated rats after acute myocardial ischemiareperfusion (64), suggesting proapoptotic and proinflammatory effects of testosterone in the heart.…”

Testosterone Stimulates Duox1 Activity through GPRC6A in Skin Keratinocytes

“…Furthermore, pretreatment of keratinocytes with NPS2143, an inhibitor of GPRC6A, completely blocked testosterone-induced apoptosis (data not shown). Because activation of caspase-3 is a hallmark of apoptosis, we measured caspase-3 activity in response to testosterone (34,36,40). The incubation of epidermal keratinocytes with testosterone revealed increasing caspase-3 activity in response to testosterone (Fig.…”

Ingenol Mebutate Signals via PKC/MEK/ERK in Keratinocytes and Induces Interleukin Decoy Receptors IL1R2 and IL13RA2

“…PKCd is a key mediator in cell differentiation and inhibition of proliferation in various tissues (31)(32)(33)(34). A direct binding of ingenol mebutate to PKC isoforms has been observed (22).…”