P4HA2 activates mTOR via hydroxylation and targeting P4HA2-mTOR inhibits lung adenocarcinoma cell growth

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Mammalian target of rapamycin (mTOR) is a crucial regulator of cell growth and metabolism.
• mTOR signaling pathway dysregulation is linked to various human diseases, notably cancer.
• Despite extensive research, the precise regulatory mechanisms of mTOR remain incompletely understood.

Purpose of the Study:

• To investigate the interaction between prolyl 4-hydroxylase alpha-2 (P4HA2) and mTOR.
• To elucidate the role of P4HA2-mediated hydroxylation in mTOR kinase activity and stability.
• To evaluate the therapeutic potential of targeting the P4HA2-mTOR axis in lung adenocarcinoma.

Main Methods:

• Biochemical assays to confirm direct binding of P4HA2 to mTOR.
• Site-directed mutagenesis to create mTOR variants (e.g., mTOR^P2341A).
• Cell-based assays and in vivo studies to assess the impact on lung adenocarcinoma cell growth.

Main Results:

• P4HA2 directly binds to mTOR and hydroxylates proline 2341 (P2341) within its kinase domain.
• Hydroxylation of P2341 activates mTOR kinase activity, enhancing phosphorylation of downstream effectors like S6K and AKT.
• P4HA2-mediated hydroxylation increases mTOR stability and substrate recognition.
• Overexpression of mTOR^P2341A reduces lung adenocarcinoma cell growth compared to wild-type mTOR.
• Targeting the P4HA2-mTOR interaction significantly inhibits lung adenocarcinoma cell growth in vivo.

Conclusions:

• P4HA2 acts as a novel activator of mTOR kinase through direct hydroxylation at P2341.
• This hydroxylation mechanism enhances mTOR stability and function, impacting cell growth.
• The P4HA2-mTOR pathway represents a promising therapeutic target for mTOR kinase-driven cancers, including lung adenocarcinoma.