6-Formylindolo(3,2-b)Carbazole (FICZ) Modulates the Signalsome Responsible for RA-Induced Differentiation of HL-60 Myeloblastic Leukemia Cells

PLoS One. 2015 Aug 19;10(8):e0135668. doi: 10.1371/journal.pone.0135668. eCollection 2015.

Abstract

6-Formylindolo(3,2-b)carbazole (FICZ) is a photoproduct of tryptophan and an endogenous high affinity ligand for aryl hydrocarbon receptor (AhR). It was previously reported that, in patient-derived HL-60 myeloblastic leukemia cells, retinoic acid (RA)-induced differentiation is driven by a signalsome containing c-Cbl and AhR. FICZ enhances RA-induced differentiation, assessed by expression of the membrane differentiation markers CD38 and CD11b, cell cycle arrest and the functional differentiation marker, inducible oxidative metabolism. Moreover, FICZ augments the expression of a number of the members of the RA-induced signalsome, such as c-Cbl, Vav1, Slp76, PI3K, and the Src family kinases Fgr and Lyn. Pursuing the molecular signaling responsible for RA-induced differentiation, we characterized, using FRET and clustering analysis, associations of key molecules thought to drive differentiation. Here we report that, assayed by FRET, AhR interacts with c-Cbl upon FICZ plus RA-induced differentiation, whereas AhR constitutively interacts with Cbl-b. Moreover, correlation analysis based on the flow cytometric assessment of differentiation markers and western blot detection of signaling factors reveal that Cbl-b, p-p38α and pT390-GSK3β, are not correlated with other known RA-induced signaling components or with a phenotypic outcome. We note that FICZ plus RA elicited signaling responses that were not typical of RA alone, but may represent alternative differentiation-driving pathways. In clusters of signaling molecules seminal to cell differentiation, FICZ co-administered with RA augments type and intensity of the dynamic changes induced by RA. Our data suggest relevance for FICZ in differentiation-induction therapy. The mechanism of action includes modulation of a SFK and MAPK centered signalsome and c-Cbl-AhR association.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-ribosyl Cyclase 1 / metabolism
  • Antineoplastic Agents / pharmacology*
  • Biomarkers / metabolism
  • CD11b Antigen / metabolism
  • Carbazoles / pharmacology*
  • Cell Cycle Checkpoints / drug effects
  • Cell Differentiation / drug effects*
  • Cell Line, Tumor
  • Gene Expression Regulation, Leukemic / drug effects
  • HL-60 Cells
  • Humans
  • Leukemia, Myeloid, Acute / drug therapy*
  • Leukemia, Myeloid, Acute / metabolism*
  • Mitogen-Activated Protein Kinases / metabolism
  • Proto-Oncogene Proteins c-cbl / metabolism
  • Receptors, Aryl Hydrocarbon / metabolism
  • Signal Transduction / drug effects
  • Tretinoin / pharmacology*
  • src-Family Kinases / metabolism

Substances

  • 6-formylindolo(3,2-b)carbazole
  • Antineoplastic Agents
  • Biomarkers
  • CD11b Antigen
  • Carbazoles
  • Receptors, Aryl Hydrocarbon
  • Tretinoin
  • Proto-Oncogene Proteins c-cbl
  • src-Family Kinases
  • Mitogen-Activated Protein Kinases
  • ADP-ribosyl Cyclase 1