Torin2 Exploits Replication and Checkpoint Vulnerabilities to Cause Death of PI3K-Activated Triple-Negative Breast...

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• The PI3K/AKT/mTOR pathway is frequently mutated in cancers, yet targeted therapies have limited clinical success.
• Triple-negative breast cancer (TNBC) often exhibits high PI3K pathway activity and is primarily treated with chemotherapy.

Purpose of the Study:

• To systematically analyze the response of TNBC cells to various PI3K pathway inhibitors.
• To identify novel therapeutic strategies for TNBC by understanding drug mechanisms.

Main Methods:

• Screening of TNBC cells with a diverse panel of PI3K pathway inhibitors.
• Investigating the molecular mechanisms of action for effective inhibitors, including Torin2.
• Assessing drug-induced DNA damage, cell-cycle progression, and cell death.

Main Results:

• Torin2 demonstrated unusual efficacy in TNBC cells by inhibiting both mTOR and other PI3K-related kinases (PIKKs).
• Unlike mTOR-selective inhibitors, Torin2 disrupts S-phase progression and cell-cycle checkpoints, leading to DNA damage.
• The drug induced cell death via replication catastrophe or mitotic failure.

Conclusions:

• Torin2 and its analogs represent a distinct class of PI3K pathway inhibitors with potent cytotoxicity against TNBC.
• These findings suggest therapeutic potential for Torin2 analogs or combinations of mTOR and PIKK inhibitors in TNBC treatment.