DNA repair confers the resistance of
tumor cells to
DNA-damaging anticancer
therapies, while how reprogrammed metabolism in
tumor cells contributes to such process remains poorly understood.
Pyruvate kinase M2
isoform (PKM2) catalyzes the conversion of
phosphoenolpyruvate to
pyruvate and regulates the last rate-limiting step of glycolysis. Here it is shown that the glycolytic metabolite
pyruvate enhances DNA damage repair by facilitating
chromatin loading of γH2AX, thereby promoting the radiation resistance of
glioma cells. Mechanistically, PKM2 is phosphorylated at
serine (
S) 222 upon DNA damage and interacts with FACT complex, a
histone chaperone comprising SPT16 and SSRP1 subunit. The
pyruvate produced by PKM2 directly binds to SSRP1, which increases the association of FACT complex with γH2AX and subsequently facilitates FACT-mediated
chromatin loading of γH2AX, ultimately promoting DNA repair and
tumor cell survival. Intriguingly, the supplementation of exogenous
pyruvate can also sufficiently enhance FACT-mediated
chromatin loading of γH2AX and promotes
tumor cell survival upon DNA damage. The levels of PKM2 S222 phosphorylation correlate with the
malignancy and prognosis of human
glioblastoma. The finding demonstrates a novel mechanism by which PKM2-produced
pyruvate promotes DNA repair by regulating γH2AX loading to
chromatin and establishes a critical role of this mechanism in
glioblastoma radiation resistance.