Efeitos do STI571 e da citarabina sobre a proliferação e a seleção “in-vitro” de células progenitoras hematopoéticas na leucemia mielóide crônica

Abstract

SummaryThe goals of this study were to assess using thein-vitrohematopoieticprogenitorcellsculturemethod,theeffectsofSTI571andcytarabineinchronicmyeloidleukemia (CML) patients’ mononuclear cells,investigating the behavior of the growth ofhematopoietic colonies CFU-GM, studying thepercentage of apoptotic cells after treatment by flowcytometry and identifying the presence of the fusiongeneBCR/ABLbyRT-PCRandFISHinthesurvivalCMLcolonies after exposure to STI571 and cytarabine atdifferenttimesanddrugconcentrations.Thematerialsused were CML Ph positive peripheral blood and bonemarrow from patients in first chronic phase, collectedby sternal or posterior iliac crest puncture, during theclinical evaluation process. Healthy volunteers’peripheralbloodwasusedasacontrol.Peripheralbloodand bone marrow mononuclear cells were separatedby Ficoll-Hypaque gradient, and received in-vitrotreatment with STI571 and cytarabine at differentconcentrations for 24, 48 and 72 hours, and assessedafter that for proliferation index, CFU-GM coloniesgrowth,percentageofapoptoticcellsandidentificationof the fusion gene BCR/ABL by FISH and RT-PCR. Bythe proliferative assays, we could demonstrate thatcytarabine had a non-selective inhibitory effectproportional to the drug dosage, but not related withexposure time, both for normal and for CML cells.STI571 was dose dependent also and not timedependent,however,showedaselectiveeffectoverCMLcellsinlowerdosesandwithhighdosesinhibitednor-malcontrolcellsatthesameway.Byclonogenicassay,cytarabine showed a dose and time dependent andnon-selective inhibitory effect. No statistic differencewas seen by the same assay under STI571 treatment,comparing times and doses of the drug. It showed, inthe same way, selective effect in lower doses in CMLcells. Apoptosis quantification was not statisticallysignificantinthemajorityofexperiments.RT-PCRBCR/ABL performed on 16 colonies was positive in 12 andnegativein4colonies.PositivitybyFISHwasfoundin18 colonies, inconclusive in 4 and non-informativein 4. FISH was not definitely negative in any colony.Thedevelopmentofthisresearchshowedtheavailabilityof this group of techniques for the study of a variety oftherapeutic modalities for CML.Key words: Chronic myeloid leukemia;hematopoietic progenitor cells; clonogenic assay;proliferation;cytarabine;STI571;RT-PCR; fluorescentin-situhybridization;BCR/ABL.Recebido emAceito em