Phosphoinositide 3-kinase (PI3K) mediates myocardium protective signaling through phosphorylation of
phosphatidylinositol (
Ptdins) to produce
Ptdins(3,4,5)P(3).
Lipid phosphatase and
tensin homolog on chromosome 10 (PTEN) antagonizes PI3K activity by dephosphorylating
Ptdins(3,4,5)P(3); therefore, the inhibition of PTEN enhances PI3K/Akt signaling and could prevent myocardium from
ischemia-reperfusion (I/R) injury. Here we studied 1) whether the pharmacological inhibition of PTEN by
bisperoxovanadium molecules [BpV(HOpic)] attenuates simulated I/R (SIR) injury in vitro and 2) whether the administration of BpV(HOpic) either before or after
ischemia limits
myocardial infarct size (IS) and ameliorates cardiodysfunction caused by
infarction. First, adult rat cardiomyocytes were treated with or without BpV(HOpic) and then exposure to SIR. Second, anesthetized rats received BpV(HOpic) either before or after
ischemia. IS was assessed at 4 h reperfusion, and left ventricular function was evaluated by echocardiography at 28 days postreperfusion. As a result, BpV(HOpic) decreased cell death, improved 3-[4,5-yl]-2,5-diphenyltetrazolium
bromide (MTT) viability, and reduced apoptosis in cells exposed to SIR. These protective effects of BpV(HOpic) are associated with increased phospho-Akt and the repression of
caspase-3 activity. Second, the administration of BpV(HOpic) significantly reduced IS and suppressed
caspase-3 activity following I/R injury and consequentially improved cardiac function at 28 day postinfarction. These beneficial effects of BpV(HOpic) are attributed to increases in myocardial levels of phosphorylation of Akt/
endothelial nitric oxide synthase (eNOS), ERK-1/2, and
calcium-dependent
nitric oxide synthase activity. In conclusion, the pharmacological inhibition of PTEN protects against I/R injury through the upregulation of the PI3K/Akt/eNOS/ERK prosurvival pathway, suggesting a new therapeutic strategy to combat I/R injury.