Antiapoptotic and proliferative effects of low concentrations of 7β-hydroxycholesterol in human endothelial cells via ERK activation.
The atherogenic potential of oxidized low-density lipoproteins (oxLDL) has been correlated to their 7beta-hydroxycholesterol (7betaOHC) content; oxLDLs have a dual effect on endothelial cell viability, inducing apoptosis or proliferation depending on the concentration. Considering that 7betaOHC is apoptotic for endothelial cells at concentrations >/=20 mug/ml, a study on the effect of lower concentrations of 7betaOHC on human umbilical vein endothelial cells (HUVECs) was undertaken. 7betaOHC (1-10 mug/ml) increased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction of growth-factor-deprived HUVECs. This effect was due to the increased cell proliferation, determined by [(3)H]thymidine incorporation, and the reduction of apoptosis, revealed by the decreased caspase-3 activation and annexin V staining. 7betaOHC also protected against staurosporine apoptosis. 7betaOHC induced an increase in intracellular ROS antagonized by N-acetylcysteine; however, HUVECs treatment with the antioxidant did not inhibit the effects of 7betaOHC. 7betaOHC produced an increase in extracellular signal-regulated kinase (ERK) phosphorylation that was blocked by inhibitors of store-operated calcium entry 2-aminoethoxydiphenyl borate and gadolinium. MEK inhibition with PD98059 or U0126 as well as store-operated calcium entry inhibition antagonized the effect of 7betaOHC. The results suggest that 7betaOHC promotes HUVECs survival and proliferation by a mechanism independent of ROS production and involving calcium-dependent activation of ERK.
Trevisi
Lucia
L
Department of Pharmacology and Anesthesiology, University of Padova, Padova, Italy. lucia.trevisi@unipd.it
Bertoldo
Alessandro
A
Agnoletto
Laura
L
Poggiani
Chiara
C
Cusinato
Federico
F
Luciani
Sisto
S
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D020013:Calcium Signaling / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D006888:Hydroxycholesterols; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; C011724:cholest-5-en-3 beta,7 alpha-diol; D048049:Extracellular Signal-Regulated MAP Kinases