p38 MAPK downregulates phosphorylation of Bad in doxorubicin-induced endothelial apoptosis

Area of Science:

• Cell Biology
• Molecular Biology
• Pharmacology

Background:

• Doxorubicin is a widely used anthracycline chemotherapy agent.
• Its antitumor activity is linked to apoptosis induction in proliferating endothelial cells.

Purpose of the Study:

• To elucidate the molecular mechanisms of doxorubicin-induced apoptosis in human endothelial cells.
• To investigate the roles of p38 MAPK and Akt signaling pathways in this process.

Main Methods:

• Cultured human endothelial cells were treated with doxorubicin.
• Inhibition of p38 MAPK and Akt signaling pathways was achieved using dominant-negative constructs and pharmacological inhibitors (SB203580).
• Caspase-3 activity, cell death, and protein phosphorylation (Akt, Bad) and expression (Bcl-xL) were assessed.

Main Results:

• Doxorubicin-induced apoptosis was mediated by p38 MAPK, as evidenced by inhibition with dominant-negative p38 MAPK or SB203580.
• Inhibition of phosphatidylinositol-3-kinase/Akt signaling potentiated doxorubicin-induced caspase-3 activity and cell death.
• Doxorubicin-induced apoptosis involved p38 MAPK-dependent inhibition of Akt and Bad phosphorylation, and downregulation of Bcl-xL.

Conclusions:

• p38 MAPK is a critical mediator of doxorubicin-induced endothelial cell apoptosis.
• Akt acts as a survival factor, and its inhibition enhances doxorubicin's cytotoxic effects.
• These findings provide insights into the molecular basis of doxorubicin's efficacy and potential therapeutic strategies.