Inhibition of dUTPase induces synthetic lethality with thymidylate synthase-targeted therapies in non-small cell lung cancer

Peter M Wilson, Melissa J LaBonte, Heinz-Josef Lenz, Philip C Mack, Robert D Ladner, Melissa LaBonte Wilson

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Chemotherapies that target thymidylate synthase (TS) continue to see considerable clinical expansion in non-small cell lung cancer (NSCLC). One drawback to TS-targeted therapies is drug resistance and subsequent treatment failure. Novel therapeutic and biomarker-driven strategies are urgently needed. The enzyme deoxyuridine triphosphate nucleotidohydrolase (dUTPase) is reported to protect tumor cells from aberrant misincorporation of uracil during TS inhibition. The goal of this study was to investigate the expression and significance of dUTPase in mediating response to TS-targeted agents in NSCLC. The expression of dUTPase in NSCLC cell lines and clinical specimens was measured by quantitative real-time reverse transcriptase PCR and immunohistochemistry. Using a validated RNA interference approach, dUTPase was effectively silenced in a panel of NSCLC cell lines and response to the fluoropyrimidine fluorodeoxyuridine (FUdR) and the antifolate pemetrexed was analyzed using growth inhibition and clonogenic assays. Apoptosis was analyzed by flow cytometry. Significant variation in the quantity and cellular expression of dUTPase was observed, including clear evidence of overexpression in NSCLC cell line models and tumor specimens at the mRNA and protein level. RNA interference-mediated silencing of dUTPase significantly sensitized NSCLC cells to growth inhibition induced by FUdR and pemetrexed. This sensitization was accompanied by a significant expansion of intracellular dUTP pools and significant decreases in NSCLC cell viability evaluated by clonogenicity and apoptotic analyses. Together, these results strongly suggest that uracil misincorporation is a potent determinant of cytotoxicity to TS inhibition in NSCLC and that inhibition of dUTPase is a mechanism-based therapeutic approach to significantly enhance the efficacy of TS-targeted chemotherapeutic agents.

Original languageEnglish
Pages (from-to)616-28
Number of pages13
JournalMolecular Cancer Therapeutics
Volume11
Issue number3
DOIs
Publication statusPublished - Mar 2012

Keywords

  • Aged
  • Antimetabolites, Antineoplastic
  • Apoptosis
  • Carcinoma, Non-Small-Cell Lung
  • Cell Line, Tumor
  • Cell Survival
  • Deoxyuracil Nucleotides
  • Floxuridine
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Neoplastic
  • Glutamates
  • Guanine
  • Humans
  • Immunoblotting
  • Immunohistochemistry
  • Lung Neoplasms
  • Pyrophosphatases
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Thymidylate Synthase

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