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Inhibition of Kynurenine Signaling Decreases Glioblastoma Multiforme Genomic Instability and Sensitizes Cells to Chemotherapeutic Treatment
Author(s) -
Reed Megan R,
Maddukuri Leena,
Helm Emily,
Bostian April C.L.,
Zafar Maroof K,
Eoff Robert L
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.754.9
Subject(s) - dna damage , aryl hydrocarbon receptor , dna repair , genome instability , cell cycle checkpoint , cell cycle , cancer research , chemistry , kynurenine pathway , microbiology and biotechnology , dna , biology , kynurenine , apoptosis , biochemistry , tryptophan , gene , transcription factor , amino acid
Glioblastoma multiforme (GBM) is an aggressive grade IV astrocytoma that is commonly treated with genotoxic compounds. Aberrant activation of the aryl hydrocarbon receptor (AhR) through mis‐regulation of the kynurenine pathway (KP) in GBM cells contributes to the malignant properties of these tumors. Our group determined that AhR activation by the KP led to an increase in chromosomal damage and that this was due, in part, to increased expression of the translesion DNA polymerase hpol κ. Based on these results, we hypothesized that blocking the rate‐limiting step in kynurenine (KYN) production through inhibition of the enzyme tryptophan 2,3‐dioxygenase (TDO) would sensitize GBM cells to genotoxic treatment by reducing the basal levels of proteins and enzymes that facilitate tolerance/repair of DNA damage. GBM cells pre‐treated with the TDO inhibitor 680C91 were found to be more sensitive to the DNA damaging agents cis‐diamminedichloroplatinum (CDDP) and bis‐chloroethylnitrosourea (BCNU). Flow cytometry analysis of GBM cell lines treated with 680C91 in combination with CDDP or BCNU revealed an enrichment in cells with 4N (G2/M) and 1N (sub‐G1) DNA content. These results are consistent with the promotion of cell cycle arrest and death following DNA damage when KYN/AhR signaling is blocked. To study global changes in replication fork dynamics, replication‐associated proteins were enriched using affinity‐mediated isolation of proteins on nascent DNA (AMIPOND). Analysis of the resulting mass spectrometry data indicate that when GBM cells are treated with 680C91 there is a broad depletion of DNA damage response and repair proteins near sites of active DNA synthesis. Immunoblotting was used to support trends observed in the proteomics results. In conclusion, our study provides support for a model in which inhibition of TDO sensitizes GBM‐derived cells to genotoxic drugs through depletion of DNA repair/damage tolerance factors. Support or Funding Information Support or Funding Information: Supported by NIH grants CA183895 to RLE and CA140409 to PAC. This research was also supported by a grant from the Arkansas Breast Cancer Research Program, the UAMS CTSA and a Seeds of Science Award from the Winthrop P. Rockefeller Cancer Institute.