Inhibition of tryptophan 2,3-dioxygenase impairs DNA damage tolerance and repair in glioma cells

ABSTRACT: Expression of tryptophan 2,3-dioxygenase (TDO) is a determinant of malignancy in gliomas through kynurenine (KYN) signaling. We report that inhibition of TDO activity attenuated recovery from replication stress and increased the genotoxic effects of bis-chloroethylnitrosourea (BCNU). Activation of the Chk1 arm of the replication stress response (RSR) was reduced when TDO activity was blocked prior to BCNU treatment, whereas phosphorylation of serine 33 (pS33) on replication protein A (RPA) was enhanced - indicative of increased fork collapse. Analysis of quantitative proteomic results revealed TDO-dependent changes in several pathways - including down-regulation of 53BP1 and sirtuin signaling. We went on to show that cells lacking TDO activity exhibited defective recruitment of 53BP1 to gamma-H2AX foci, which corresponded with delayed repair of DNA breaks. Addition of exogenous KYN increased the rate of break repair. TDO inhibition diminished SIRT7 deacetylase recruitment to chromatin, which increased histone H3K18 acetylation - a key mark involved in preventing 53BP1 recruitment to sites of DNA damage. These results highlight the potential for tumor-specific metabolic changes to influence genome stability and may have implications for glioma treatment strategies.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Stephanie Byrum  

LAB HEAD: Robert L. Eoff

PROVIDER: PXD022351 | Pride | 2021-09-09

REPOSITORIES: Pride