Class 1A PI3K regulates vessel integrity during development and tumorigenesis

Area of Science:

• Oncology
• Molecular Biology
• Vascular Biology

Background:

• Phosphoinositide 3-kinase (PI3K) signaling is crucial for tumor cell growth, proliferation, and survival.
• The role of PI3K in the tumor microenvironment, particularly in regulating tumor vasculature, is less understood.

Purpose of the Study:

• To investigate the role of class 1A PI3K in maintaining the integrity of tumor vasculature.
• To determine the therapeutic potential of targeting class 1A PI3K in cancer.

Main Methods:

• Generated mice with endothelial cell-specific loss of class 1A PI3K using Tie2Cre-mediated deletion of PI3K regulatory subunits.
• Assessed vascular integrity and tumor growth in heterozygous mice under normal and pathological conditions (tumor cells, VEGF).
• Evaluated the effect of a PI3K inhibitor on tumor angiogenesis.

Main Results:

• Complete loss of class 1A PI3K subunits resulted in embryonic lethality, while heterozygous mice were viable.
• Heterozygous mice showed no vascular defects until challenged, exhibiting localized vascular abnormalities and reduced tumor growth.
• PI3K inhibition mimicked the effects of PI3K loss, decelerating tumorigenesis.

Conclusions:

• Endothelial class 1A PI3K is critical for maintaining tumor vasculature integrity, especially under pathological conditions.
• Targeting class 1A PI3K represents a potential therapeutic strategy to inhibit tumor angiogenesis and control tumor progression.