Identification and characterization of two novel oncogenic mTOR mutations

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Aberrant activation of mammalian target of rapamycin (mTOR) signaling is common in human cancers.
• mTOR inhibitors are promising anti-cancer drugs, but identifying specific genetic alterations is crucial for guiding treatment.
• Understanding the genetic drivers of mTOR activation can reveal novel therapeutic targets.

Purpose of the Study:

• To identify and characterize novel oncogenic mutations in the mTOR gene.
• To investigate the functional consequences of these mutations in vitro and in vivo.
• To assess the potential of these mutations as therapeutic targets for mTOR inhibitors.

Main Methods:

• Sequencing of 30 exons of the mTOR gene in thyroid and melanoma cancer samples.
• Functional characterization of identified mTOR mutants using cell lines (HEK293T, NIH3T3).
• In vivo studies involving inoculation of mutant-expressing cells in athymic nude mice.

Main Results:

• Identified novel point mutations A1256G and G7076A in the mTOR gene.
• Over-expression of mTOR mutants (H419R, G2359E) resulted in elevated kinase activity and mTOR/p70S6K signaling.
• Mutant mTOR expression induced oncogenic transformation, anchorage-independent growth, invasion, and rapid tumor development in mice.
• Mutant-expressing cells showed increased sensitivity to the mTOR inhibitor temsirolimus.

Conclusions:

• Novel oncogenic mTOR mutations (H419R, G2359E) were identified and functionally characterized.
• These mutations activate mTOR signaling, promote cancer development, and sensitize cells to mTOR inhibitors.
• Cancers, including anaplastic thyroid cancer and melanoma, harboring these specific mTOR mutations may benefit from mTOR-targeted therapies.