title: In vitro sensitivity of CLL cells to fludarabine may be modulated by the stimulation of Toll-like receptors.
abstract: OBJECTIVE
  The emerging role of Toll-like receptors (TLR) in the pathogenesis of chronic lymphocytic leukemia (CLL) led us to ask whether TLR stimulation may protect CLL cells from drug-induced apoptosis.
  
  
  METHODS
  We cultured in vitro malignant B cells freshly isolated from 44 patients with CLLs in the presence or the absence of different concentrations of fludarabine before or after 24-hour TLR stimulation with specific ligands and evaluated cell viability, apoptosis, and molecular pathways involved.
  
  
  RESULTS
  Heterogeneity was observed among samples. In leukemic cells from patients bearing adverse prognostic factors, TLR stimulation caused a significant increase of protection to fludarabine treatment, whereas this did not occur in the cells from patients with good prognosis. To identify novel molecular mechanisms accounting for the dichotomy of response between the two groups of patients, we conducted an apoptosis gene expression profile on leukemic cells either unstimulated or stimulated with TLR9 ligand. Strikingly, TLR9 stimulation specifically upregulated the expression of lymphotoxin-α in cells where an increased protection to fludarabine treatment was observed. Also, the expression of miR-155-3p was significantly increased after stimulation of distinct TLR in cells where fludarabine treatment was less effective.
  
  
  CONCLUSIONS
  These results suggest that at least in a proportion of patients, in vitro sensitivity to fludarabine may be modulated by the stimulation of TLR, likely mimicking microenvironmental signals occurring in vivo.
authors.affiliation: San Raffaele Scientific Institute, Division of Molecular Oncology; Università Vita-Salute San Raffaele, Via Olgettina 58, Milan, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Fonte
authors.forename: Benedetta
authors.initials: B
authors.lastname: Apollonio
authors.forename: Lydia
authors.initials: L
authors.lastname: Scarfò
authors.forename: Pamela
authors.initials: P
authors.lastname: Ranghetti
authors.forename: Claudia
authors.initials: C
authors.lastname: Fazi
authors.forename: Paolo
authors.initials: P
authors.lastname: Ghia
authors.forename: Federico
authors.initials: F
authors.lastname: Caligaris-Cappio
authors.forename: Marta
authors.initials: M
authors.lastname: Muzio
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics / Q000378:metabolism*; D008233:Lymphotoxin-alpha / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics; D011379:Prognosis; D051193:Toll-Like Receptors / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D008233:Lymphotoxin-alpha; C524942:MIRN155 microRNA, human; D035683:MicroRNAs; D051193:Toll-Like Receptors; D014740:Vidarabine; C024352:fludarabine