Platelet PI3Kβ regulates breast cancer metastasis

Area of Science:

• Oncology
• Hematology
• Cell Biology

Background:

• Platelets contribute to tumor metastasis through various mechanisms, including promoting cancer cell invasion and extravasation.
• Platelet activation, crucial for thrombus formation, relies on Class IA phosphoinositide 3-kinase beta (PI3Kβ).

Purpose of the Study:

• To investigate the role of platelet PI3Kβ in breast cancer metastasis.
• To explore PI3Kβ as a potential therapeutic target for inhibiting cancer metastasis.

Main Methods:

• Utilized PI3Kβ mutant mice to assess platelet function in vitro and in vivo.
• Performed RNAseq and proteomic analysis on co-cultured human breast epithelial cells and platelets.
• Examined the impact of PI3Kβ on tumor cell signaling pathways (YAP and Smad2).
• Assessed spontaneous and experimental metastasis in mouse models.

Main Results:

• Platelet PI3Kβ is essential for platelet-stimulated tumor cell invasion and metastasis.
• PI3Kβ deficiency in platelets reduced in vitro tumor cell binding and platelet activation.
• Platelet PI3Kβ regulates the expression of epithelial-mesenchymal transition (EMT) and metastasis-associated genes, including PAI-1 and IL-8.
• PI3Kβ mutant platelets impaired YAP and Smad2 signaling in tumor cells.
• Mice with mutant PI3Kβ exhibited reduced spontaneous metastasis, and their platelets were less effective in promoting experimental metastasis.

Conclusions:

• Platelet PI3Kβ plays a critical role in promoting breast cancer metastasis.
• Targeting platelet PI3Kβ with selective inhibitors presents a promising therapeutic strategy for treating cancer metastasis.