title: Effect of cytotoxic chemotherapy on markers of molecular age in patients with breast cancer.
abstract: BACKGROUND
  Senescent cells, which express p16 (INK4a) , accumulate with aging and contribute to age-related pathology. To understand whether cytotoxic agents promote molecular aging, we measured expression of p16 (INK4a) and other senescence markers in breast cancer patients treated with adjuvant chemotherapy.
  
  
  METHODS
  Blood and clinical information were prospectively obtained from 33 women with stage I to III breast cancer at four time points: before anthracycline-based chemotherapy, immediately after anthracycline-based chemotherapy, 3 months after anthracycline-based chemotherapy, and 12 months after anthracycline-based chemotherapy. Expression of senescence markers p16 (INK4a) and ARF mRNA was determined using TaqMan quantitative reverse-transcription polymerase chain reaction in CD3(+) T lymphocytes, telomere length was determined by Southern analysis, and senescence-associated cytokines were determined by enzyme-linked immunosorbent assay. Findings were independently assessed in a cross-sectional cohort of 176 breast cancer survivors enrolled a median of 3.4 years after treatment; 39% previously received chemotherapy. All statistical tests were two-sided.
  
  
  RESULTS
  In prospectively analyzed patients, expression of p16 (INK4a) and ARF increased immediately after chemotherapy and remained elevated 12 months after treatment. Median increase in log2 p16 (INK4a) was 0.81 (interquartile range = 0.28-1.62; Wilcoxon signed-rank P < .001), or a 75% absolute increase in expression, equivalent to the increase observed over 14.7 years of chronological aging. ARF expression was comparably increased (P < .001). Increased expression of p16 (INK4a) and ARF was associated with dose-dense therapy and hematological toxicity. Expression of two senescence-associated cytokines (VEGFA and MCP1) was durably increased by adjuvant chemotherapy. Telomere length was not affected by chemotherapy. In a cross-sectional cohort, prior chemotherapy exposure was independently associated with a log2-increase in p16 (INK4a) expression of 0.57 (repeated measures model, P < .001), comparable with 10.4 years of chronological aging.
  
  
  CONCLUSIONS
  Adjuvant chemotherapy for breast cancer is gerontogenic, inducing cellular senescence in vivo, thereby accelerating molecular aging of hematopoietic tissues.
authors.affiliation: Affiliations of authors: Lineberger Comprehensive Cancer Center (HKS, AMD, JK, CT, JS, JGI, LAC, AD, B-BG, SA, NES, HBM), Department of Medicine (HKS, TAJ, GW, LAC, NES, HBM), Department of Genetics (JK, CT, NES), and Department of Biostatistics (JGI), University of North Carolina, Chapel Hill, NC; Department of Medicine, University of Virginia, Charlottesville, VA (PD); Department of Medical Oncology and Therapeutics Research, City of Hope Cancer Center, Duarte, CA (AH); Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany (KK, KLR).
authors.forename: Hanna K
authors.initials: HK
authors.lastname: Sanoff
authors.forename: Allison M
authors.initials: AM
authors.lastname: Deal
authors.forename: Janakiraman
authors.initials: J
authors.lastname: Krishnamurthy
authors.forename: Chad
authors.initials: C
authors.lastname: Torrice
authors.forename: Patrick
authors.initials: P
authors.lastname: Dillon
authors.forename: Jessica
authors.initials: J
authors.lastname: Sorrentino
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Ibrahim
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Jolly
authors.forename: Grant
authors.initials: G
authors.lastname: Williams
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Carey
authors.forename: Amy
authors.initials: A
authors.lastname: Drobish
authors.forename: Brittaney-Belle
authors.initials: BB
authors.lastname: Gordon
authors.forename: Shani
authors.initials: S
authors.lastname: Alston
authors.forename: Arti
authors.initials: A
authors.lastname: Hurria
authors.forename: Karin
authors.initials: K
authors.lastname: Kleinhans
authors.forename: K Lenhard
authors.initials: KL
authors.lastname: Rudolph
authors.forename: Norman E
authors.initials: NE
authors.lastname: Sharpless
authors.forename: Hyman B
authors.initials: HB
authors.lastname: Muss
mesh_terms: D020727:ADP-Ribosylation Factors / Q000097:blood*; D000328:Adult; D000368:Aged; D000818:Animals; D018943:Anthracyclines / Q000008:administration & dosage / Q000009:adverse effects*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D016922:Cellular Senescence / Q000187:drug effects*; D003430:Cross-Sectional Studies; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000097:blood*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism; D016615:Telomere
chemical_list: D018943:Anthracyclines; D015415:Biomarkers; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016207:Cytokines; D020727:ADP-Ribosylation Factors