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

VIII Congress of the Italian Society of Experimental Hematology, Pavia, September 14-16, 2004105RANK in MM cells and in the BM environment andthe potential role of RANKL in the interaction ofmyeloma cells with the microenvironment. First, wefailed to detect RANKL in several human myelomacell lines (HMCLs) and fresh purified MM cells. RANKwas expressed in BMSC and endothelial cells but notin myeloma cells. Consistently, RANKL had not adirect effect on myeloma cell survival. RANKL treatmentsignificantly induced an increase of interleukin(IL)-6 and IL-11 secretion by both BMSC andendothelial cells. Moreover, in a co-culture systemwe found that myeloma cells up-regulated both IL-6and IL-11 secretion by BMSC and endothelial cellsthrough the cell-to-cell contact. The presence of theRANK-Fc that blocks the RANK/RANKL interactionsignificantly inhibited HMCLs induced secretion ofIL-6 and IL-11. Our data provide new notions on therole of RANKL system in the pathophysiology of MM.PO-069CHEMOKINE RECEPTORS CXCR3 AND CXCR4 EXPRESSION ANDROLE IN PLASMA CELL MALIGNANCYGiuliani N, Bonomini S, Hojden M, Colla S, MorandiF, Sammarelli G, Rizzoli VCattedra di Ematologia, Università di Parma, ItalyChemokine receptors, CXCR3 and CXCR4, areexpressed on normal B and plasma cells beinginvolved in regulation of chemotaxis and migration.In this study we have evaluated the potential expressionand role CXCR3 and CXCR4 on human myelomacells. First we found that fresh purified CD138 + plasmacells obtained from 25 multiple myeloma (MM)patients at the diagnosis expressed both CXCR3 andCXCR4 on the membrane in a wide range of expression.A significant increase of both chemokine receptorswas found in comparison with normal subjects,moreover a correlation between CXCR3 expressionand the clinical stage of MM patients was found.Human myeloma cell lines (HMCL), RPMI-8226,OPM-2, XG-1, XG-6, OPM-2 established frompatients with plasma cell leukemia, also expressedCXCR4 at high intensity. CXCR3 was expressed in 2(RPMI-8226 and OPM-2) out of 5 HMCL tested atlower intensity. CXCR3 expression was cell cycledependent being associated with the proliferativephase of cell cycle. In addition CXCR3 expression onHMCL, detected by both flow cytometry andimmunoistochemistry, was up-regulated during cellapoptosis induced with CD95 stimulation or IL-6deprivation. Using an ELISA test we have also demonstratedthat 3 out 4 HMCL produced the CXCR3 ligandIFNgamma inducible protein (IP-10). A significantinhibitory effect on HMCL apoptosis was observed bytreating them with IP-10 at concentration rangingbetween 50 to 100 ng/ml. In conclusion our data indicatethat myeloma cells express CXCR3 and CXCR4with a different pattern and at higher intensity ascompared to normal subjects and that CXCR3 expressionby myeloma cell is correlated with cycle andapoptosis and in turn CXCR3 activation by IP-10 canaffect myeloma cell survival.PO-070HUMAN MYELOMA CELLS INHIBIT OSTEOBLAST FORMATIONAND DIFFERENTATION IN THE BONE MARROW ENVIRONMENTGiuliani N, Morandi F, Colla S, Bonomini S,Hojden M, Rizzoli VCattedra di Ematologia, Università di Parma, ItalyMultiple myeloma (MM) is a plasma cell malignancycharacterized by the high capacity to induceosteolytic lesions. The histomorphometric studies,performed in MM patients, have demonstrated thatMM patients with high plasma cell infiltrate or activedisease are characterized by a lower number ofosteoblasts and a decreased bone formation thatcontributes, together with the increased osteoclastactivity, in the development of bone lesions. Howeverthe mechanisms by which myeloma cells reducebone formation are not completely identified. In thisstudy first we have investigated the effect of humanmyeloma cell lines (HMCLs) on proliferation and survivalof osteoblast-like cell lines MG-63 and primaryhuman osteoblast cells (hOB) in a co-culture system.We found that conditioned medium (CM) ofRPMI-8226, U266, XG-1 and XG-6 significantlyreduced the number osteoblastic cells and suppressedosteoblast proliferation of both MG-63 and hOB.HMCLs are able to significantly induce apoptosis ofhuman osteoblastic cells either in presence orabsence of a transwell insert even if the cell-to-cellcontact condition was more effective. CD95/FAS+osteoblastic cells, as MG-63, are more sensitive toHMCLs apoptosis. Consistently the presence of blockinganti-FAS ligand Ab in the co-culture reduced thepro-apoptotic effect but not completely. Similarly wefound that blocking anti-TRIAL Ab also reducedosteoblast apoptosis but did not completely blunt thepro-apoptotic effect of TRIAL positive HMCLs. Further,we have investigated the effect of HMCLs on the formationof osteoblast progenitors in long-term humanbone marrow (BM) cultures. In this system we foundthat HMCLs significantly inhibited both the numberof the Colony Forming Unit-fibroblast (CFU-F) after15 days and of the CFU-OB after 21 days either inpresence or absence of a transwell system even if thecell-to-cell contact induced a more potent inhibitoryeffect. Moreover, in a co-culture system, we foundthat myeloma cells inhibited the osteoblast dif-haematologica vol. 89[suppl. n. 6]:september 2004