Haematologica 2004;89: supplement no. 6 - Supplements ...

122PostersPosterNON-ONCOLOGICAL HEMATOLOGYPO-098DUAL EFFECT OF ARSENIC TRIOXIDE ON HEMOPOIESIS:INHIBITION OF ERYTHROPOIESIS AND STIMULATION OFMEGAKARYOCYTOPOIESISSaulle E, Riccioni R, Pelosi E, Rossini A, Petrucci E,Pasquini L, De Tuglie G, Calabrò L, Stafsnes M,Peschle C, Testa UDipartimento di Ematologia, Oncologia e Medicinamolecolare, Istituto Superiore di Sanità, Rome, ItalyArsenic compounds, including arsenic trioxide(As2O3) and arsenic disulfide, utilized in some traditionalChinese remedies, have been demostrated to beeffective for the treatment of Acute PromyelocyticLeukemia (APL), when used at low doses. However,As2O3 is also a potent inducer of apoptosis in a numberof other cancer cells such as AML, gastric cancer,neuroblastoma. The exact mechanism of As203induced apoptosis in the cells is not yet clear. In thepresent study we investigated the effect of As2O3 onerythropoiesis and megakaryocytopoiesis. DuringAs203 treatment of the human erythroleukemic cellline HEL several changes were observed: stimulationof megakaryocytic differentiation, inhibition of severalerythroid markers and induction of apoptosis atthe same time. Particularly,the expression of erythroid-specificreceptors such as c-Kit, Epo-R, GlycA,were downmodulated after As2O3 exposure. Similarobservations have been made in K562 cells. The samephenomenon was observed during unilineage erythroidand megakaryocytic cultures from normalhemopoietic progenitor cells : blockade of erythropoiesisand stimulation of megakaryocytopoiesis, asshown by cell cycle, morphologic and immunophenotypicanalyses. To determine whether the engagmentof caspases is involved in these phenomena weanalyzed the expression of GATA-1 and Tal-1 transcriptionfactors, two targets of caspases, whoseintegrity and activity is essential for the developmentand survival of the erythroid lineage. After exposureof HEL and K562 cells to As203 for 48h we observeda decrease of GATA-1 and Tal-1 expression; moreover,treatment with pan-caspase inhibitor z-VAD incombination with As203, protects GATA-1 fromcleavage. In unilineage cultures of normal erythroidprogenitors the addition of As203 resulted in a blockadeof erythroid maturation at the proerythroblasticstage, associated with a cleavage of both GATA-1and Tal-1 transcription factors. Both the As203-induced inhibition of erythroid cell differentiationand cleavage of transcription factors was blocked byzVAD. In contrast, the addition of As203 to unilineagecultures of normal megakaryocytic precursors did notinduce any cleavage of GATA-1 and Tal-1 transcriptionfactors and induced a stimulation of megakaryocyticmaturation (i. e. , increase in the formation ofthe large polyploid megakaryocytes). The stimulatoryeffect of As203 on megakaryocytic maturationseems to require caspase activation. Experiments arein progress to determine the caspase required for theinhibitory and stimulatory effect of As203 on erythropoiesisand megakaryocytopoiesis, respectively.Our results clearly indicate that the effects of As203on hematopoiesis are lineage specific and the markedinhibitory effect of this compound on erythropoiesiscould explain the development of anemia oftenobserved during therapy based on As2O3 administration.PO-099USE OF THE BLOB ANALYSIS IN THE DEVELOPMENT OF A NEWPROCEDURE FOR THE AUTOMATIC COUNT OF GRANULOCYTESMIGRATING THROUGH MICROPORE FILTERS IN CHEMOTACTICBOYDEN CHAMBERAzzarà A, Chimenti M,* Carulli G, Galimberti S,Fazzi R, Andreazzoli F, Petrini MDivisione di Ematologia, Dipartimento di Oncologia,dei Trapianti e delle Nuove tecnologie in Medicina,Università di Pisa, Italy; Divisione di Ematologia,Dipartimento di Oncologia, dei Trapianti e delleNuove tecnologie in Medicina, Università di Pisa,Italy; * Istituto Di Scienza e Tecnologie dell'Informazione“A. Faedo”. Consiglio Nazionale delle Ricerche,Pisa, ItalyIn this paper we describe a completely new imageprocessing procedure for an automatic assessmentof granulocyte motility in micropore filters. Granulocytemotility was evaluated in perspex chemotacticchambers according to the Boyden method, usingmixed-ester filters between the two compartments.After treatment, the filters were fixed, dehydrated,stained, diaphanized and placed on the electromechanicaltable of a Leitz Hortolux microscope.According to our procedure, the objective is focusedon the upper plane of the filter and a sequence of digitalimages is then acquired at predetermined depthsby means of a video camera. The video signal is sentto a video board which can store digital imagesdefined by 768×576 pixels with 300 µm spatial resolution.The frame grabber works on a personal computerunder the control of the Matrox Inspector(R)software, which uses several options, such as Seg-haematologica vol. 89[suppl. n. 6]:september 2004