Haematologica 2003 - Supplements

Fig.1 IFN-induced senstitization to Fas-induced apoptosis is
independent of TRAIL. Agonistic as-antibody CH11(FasL),
recombinant soluble Apo2L/TRAIL (rTRAIL) or isotype specific
control IgM in the presence (right panels) of blocking agent
rhTRAIL-R1:Fc (Fc-DR4) was continually added in the
experiments. The percentage of Annexin V-positive/PI-negative
apoptopic cells was evaluated by flow cytometry and indicated.
References
H. Spets, P. Georgii-Hemming, J Siljason, K. Nilsson, H.
JernbergWiklund: fas/APO-1 (CD95) mediated apoptosis is
activated by interferon-α and interferon-γ in IL-6 dependent and
IL-6 independent myeloma cell lines. Blood 92(8) 2914-2923
(1998).
K. Nilsson P. Georgii-Hemming, H. Spets and H. Jernbergwiklund.
In: Melchers F, Potter M, eds. Mechanisms of B Cell
Neoplasia. Berlin: Springer Verlag. The control of proliferation,
survival and apoptosis in human multiple myeloma cells in vitro
pp325-335 (1998).
R. Catlett-Falcone et al.: Constitutive Activation of Stat3
Signaling Confers resistance to Apoptosis in Human U266
Myeloma Cells. Imunity Vol. 10 105-115 (1999)
A. Dimberg*, L. Dimberg*, K. Nilsson, F. Öberg and H.
Jernberg-Wiklund: IFN-γ-induced Sensitization to Fas-induced
Apoptosis in Multiple Myeloma Cells is Associated with a Shift
in STAT Activationand an Upregulation of Fas and TRAIL
(submitted 2003). * equal contribution.
P3.6
PHENOTYPIC HETEROGENEITY OF MYELOMA CELLS
AND ITS BIOLOGICAL SIGNIFICANCE
Michio M. Kawano, Hideaki Ishikawa, Naohiro Tsuyama,
Saeid Abroun, Shangqin Liu, Fu-Jun Li, Ken-Ichiro
Otsuyama, Xu Zheng, Masanori Obata.
Department of Bio-Signal Analysis, AMES, Graduate School of
Medicine, Yamaguchi Univ., Ube, Japan
In human myelomas, there is a heterogeneity of myeloma cells
morphologically and phenotypically. Myeloma cells can be
classified phenotypically into at least 5 subpopulations; MPC-1-
CD45+CD49e-, MPC-1-CD45-CD49e- immature myeloma cells,
MPC-1+CD45-CD49e-, MPC-1+CD45+CD49e- intermediate
myeloma cells and MPC-1+CD45+CD49e+ mature myeloma
cells. Immature myeloma cells( MPC-1-CD49e-) have a capacity
of proliferating in vitro and in vivo, but only CD45+ immature
myeloma cells can response directly to IL-6 to proliferate. In
the U-266 cell lines, IL-6 can lead to the induction of CD45
expression and CD45+ U-266 cells can proliferate in response to
IL-6. In both CD45- and CD45+ U-266 cells, STAT3 and
MAPK(ERK1/2) can be activated in response to IL-6 equally
between them, but src family kinases such as Lyn, Fyn can be
activated only in CD45+ U-266 cells. Thus, the activation of the
src family kinases associated with CD45 expression is a
prerequisite for the proliferation of myeloma cells. Antisense
oligonucleotides specific for Lyn, or PTK inhibitors(PP2 or
herbimycin A) blocked enhancement of IL-6-induced
proliferation of CD45+ U-266 cells. In addition, CD45+ U-266
cells were more sensitive to apoptotic stimuli such as serum-free
condition, heat shock, UV irradiation, H 2 O 2 treatment, or
melphalan treatment than CD45- U-266. Therefore, we can
speculate that in the bone marrow of human myelomas IL-6 can
induce proliferation of CD45+ immature cells, but the amount of
IL-6 is too low to support CD45+ myeloma cells and loss of
CD45 results in no direct response to IL-6 to proliferate but
confers resistance to stress condition leading to the longer
survival at the limited amount of IL-6.
Fig.1 Heterogeneity of human myeloma cells in the bone marrow
MPC-1-CD45+CD49e- immature myeloma cells can proliferate
in response to IL-6. In most cases of multiple myelomas, MPC-
1-CD45+CD49e- proliferative immature cells are only 0.1 to 2 %
of bone marrow mononuclear cells, and dominant subpopulations
are MPC-1+CD45-CD49e- intermediate cells which are
considered to be non-proliferative fractions.
S30