pathways

This KEGG map shows how cancer cells rewire the handling of choline, a nutrient used to build cell membranes, so that growth signals and membrane building feed each other. It matters because the resulting build-up of phosphocholine is visible on MR spectroscopy and PET scans and is one of the metabolic hallmarks of cancer.

Under pressure from a drug that blocks its identity (the androgen receptor in prostate cancer, EGFR in lung cancer), a tumour can change what kind of cell it is, becoming a small-cell neuroendocrine cancer that no longer needs the blocked signal. It is the ultimate escape: not a new mutation in the engine, but a new engine.

KEGG's prostate cancer map centres on the androgen receptor, the hormone switch that prostate cells depend on, plus loss of PTEN and NKX3.1 that lets PI3K/AKT growth signalling run free. Hormone therapy, AR antagonists and now AKT inhibitors act on these two arms.

The VHL/HIF pathway is how cells sense oxygen (the 2019 Nobel Prize). VHL destroys HIF when oxygen is present. Kidney cancers lose VHL, so HIF-2α is permanently on and drives blood vessel growth and proliferation.