Recent Insights Into The Pathophysiology Of mTOR Pathway Dysregulation
Research Summary
A review of how the mTOR pathway is built, what switches it on and off, and what happens in human disease when it is overactive or underactive – covering neurological disease, cancer, diabetes and cardiovascular disorders.
Who Or What Was Studied?
A review of published research rather than a new study: cell and animal experiments on mTORC1 and mTORC2 signalling, and clinical trials of mTOR inhibitors such as sirolimus (rapamycin), everolimus and temsirolimus in cancer, neurological, metabolic and cardiovascular disease.
What Did The Research Show?
- mTOR exists as two complexes, mTORC1 and mTORC2; rapamycin binds FKBP12 and inhibits mTORC1, while chronic exposure can also inhibit mTORC2.
- In cancer, the FDA approved temsirolimus for renal cell carcinoma (median overall survival 10.9 months versus interferon in a phase III trial of 626 patients) and everolimus for advanced pancreatic neuroendocrine tumours and, with exemestane, hormone receptor-positive breast cancer (median progression-free survival 10.2 versus 4.1 months).
- In neurology, everolimus reduced subependymal giant cell astrocytoma and renal angiomyolipoma burden in tuberous sclerosis complex, and mouse models show rapamycin preventing epilepsy and reducing Alzheimer-like plaques and Huntington protein aggregates.
- Chronic mTORC1 activation is described as contributing to obesity and insulin resistance through S6K1 feedback on insulin signalling, while mTORC1 also drives lipid synthesis, adipogenesis and mitochondrial output.
- In the cardiovascular system, mTOR is essential for cardiomyocyte growth; rapamycin reduced isoproterenol-induced cardiac hypertrophy in adult rats, and macrophage-specific RAPTOR deletion reduced atherosclerosis in mice.
Limitations And Interpretation
- This is a narrative review, not a trial: it reports no new experiments or patient outcomes.
- Its focus is disease treatment, not ageing; lifespan or healthspan outcomes are not evaluated.
- The authors note that rapalogs are generally cytostatic rather than cytotoxic, with moderate single-agent activity in most tumour types and combination trials limited by toxicity.
Summary prepared from the published paper (abstract and full text where accessible). This is not medical advice — always consult the original publication.