title: Depletion of deoxyribonucleotide pools is an endogenous source of DNA damage in cells undergoing oncogene-induced senescence.
abstract: In normal human cells, oncogene-induced senescence (OIS) depends on induction of DNA damage response. Oxidative stress and hyperreplication of genomic DNA have been proposed as major causes of DNA damage in OIS cells. Here, we report that down-regulation of deoxyribonucleoside pools is another endogenous source of DNA damage in normal human fibroblasts (NHFs) undergoing HRAS(G12V)-induced senescence. NHF-HRAS(G12V) cells underexpressed thymidylate synthase (TS) and ribonucleotide reductase (RR), two enzymes required for the entire de novo deoxyribonucleotide biosynthesis, and possessed low dNTP levels. Chromatin at the promoters of the genes encoding TS and RR was enriched with retinoblastoma tumor suppressor protein and histone H3 tri-methylated at lysine 9. Importantly, ectopic coexpression of TS and RR or addition of deoxyribonucleosides substantially suppressed DNA damage, senescence-associated phenotypes, and proliferation arrest in two types of NHF-expressing HRAS(G12V). Reciprocally, short hairpin RNA-mediated suppression of TS and RR caused DNA damage and senescence in NHFs, although less efficiently than HRAS(G12V). However, overexpression of TS and RR in quiescent NHFs did not overcome proliferation arrest, suggesting that unlike quiescence, OIS requires depletion of dNTP pools and activated DNA replication. Our data identify a previously unknown role of deoxyribonucleotides in regulation of OIS.
authors.affiliation: Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
authors.forename: Sudha
authors.initials: S
authors.lastname: Mannava
authors.forename: Kalyana C
authors.initials: KC
authors.lastname: Moparthy
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Wheeler
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Natarajan
authors.forename: Shoshanna N
authors.initials: SN
authors.lastname: Zucker
authors.forename: Emily E
authors.initials: EE
authors.lastname: Fink
authors.forename: Michael
authors.initials: M
authors.lastname: Im
authors.forename: Sheryl
authors.initials: S
authors.lastname: Flanagan
authors.forename: William C
authors.initials: WC
authors.lastname: Burhans
authors.forename: Nathalie C
authors.initials: NC
authors.lastname: Zeitouni
authors.forename: Donna S
authors.initials: DS
authors.lastname: Shewach
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Mathews
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Nikiforov
mesh_terms: D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics* / Q000502:physiology; D004249:DNA Damage / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics; D003854:Deoxyribonucleotides / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology; D006801:Humans; D009857:Oncogenes / Q000502:physiology*; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D012264:Ribonucleotide Reductases / Q000096:biosynthesis / Q000502:physiology; D013940:Thymidylate Synthase / Q000096:biosynthesis / Q000502:physiology
chemical_list: D003854:Deoxyribonucleotides; D012264:Ribonucleotide Reductases; D013940:Thymidylate Synthase; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)