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PKLR (pyruvate kinase L/R) encodes the liver-type
(PKL) and red-blood-cell-type (PKR) pyruvate
kinase isoforms, which catalyze the final ATP-generating step of glycolysis by
converting phosphoenolpyruvate to pyruvate. PKLR expression is normally
tissue-restricted, but aberrant expression can contribute to tumour metabolic
adaptation. In colorectal cancer, PKLR is increased in primary tumours associated
with metastatic disease and in liver metastases, where it promotes survival under
hypoxic and high-cell-density conditions partly by increasing glutathione-dependent
antioxidant capacity. PKLR has also been implicated in enhanced glycolytic
metabolism in hepatocellular carcinoma. In these tumour contexts, the typical
cancer-associated direction is up, while the desired anticancer
modulation is generally down. However, PKLR is not as universally
cancer-associated as PKM2, so its direction should remain tumour-specific. PKLR
is separate from PKM, which encodes the distinct PKM1 and PKM2
isoforms.
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