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(D4) Expression of the multidrug resistance (MDR 1) gene in MDS
r;
Second International
SECTION D -
Conference
CELL BIOLOGY
on Myelodysplastic
(D4) EXPRESSION
Dillerentiation Therapy in H. Phillip
Kocfflcr,
UCLA
Myelodyspbtic
Ronald Pquette,
Syndrome
M.D.,
School of Mcdicinc,
albeit not normally.
inducers of differentiation
were identified
differentiation
of Friend
crythrolcukemia
promyclocytic
leukemic
cells.
showed activity. cells.
leukemic
mice.
potential
by their capacity to induce
A bewildering
array of compounds on fresh
of active compounds were pursued in
interferons.
rdinoids,
vitamin
D,
and hexarnethylbiaacaamidc
13-cis rctinoic has been studied in at least 7 trials of IO or
more patients.
A minority
of patients responded; one investigator
data suggesting that sucessful therapy rquircs administration
of the compound.
studied in patients with MDS.
[I ,ZS(OH)J3,]
An-trans-rainoic
acid has not been
I ,25 dihydroxyvitamin
Because of hypercalccmia,
were severely limited;
differentiation
without
studies with S-azacvtidine these interesting are. ongoing.
results rquirc
several years to 10 ‘low&k’
MDS
differentiation
Initial
of about 45 % in
further study.
(4-9xl@U/wcek)
w
trials in
was given over
patients, 3/10 responsed.
larger study with this agent is rquired. than individual
D analogs that induce
arc being studied.
showed a responwrate
ar-Interfcroq
D,
trials; no major
amount of drug
new vitamin
causing hypercalcemia
has
months of
haa been used in three small MDS
responses occured. administered
identify
Initially,
cells and HL-60
of thcsc compounds including
analogs, S-azacytidine,
leukemia
MULTIDRUG
RESISTANCE
/MDR,)
of the
the ncoplastic clone
Paticnb with MDS have been treated with either one
or combinations (HMBA).
USA
A number of these were examined in
Further studies
leukemic
CA,
induce differentiation
Studies showed that in MDS,
W(LSable to differcntiatc,
MDS;
THE
P. Sonneveld, M. Schoester, P. te Boekhorst and K. Nooter Erasmus University, Department of Hematology, Rotterdam and Institute of Applied Radiobiology and Immunology, Rijswijk, The Netherlands.
Cedars Sinai Medical
Los Angeles.
Basic tenent ofdifferentiation therapy is to ncoplastic clone.
MDS
OF
GENE IN MDS.
(D2)
Center.
Syndromes
Combinations
A
of
inducing agents have not as yti proven more successful agents.
using all-m
Finally.
success in acute promyclocytic
retinoic acid should provide
effective agents for differentiation
of MDS
further impetus to cells.
(JW
(D3)
GROWTH
Over-expression of the Multidrug Resistance gene (IJ&,) is associated with clinical resistance to a variety of cytostatic agents including important antileukemic drugs, i.e., anthracyclines, vinca alkaloids and etoposide. Acute Myeloid Leukemia (AML) developing from myelodysplasia (MDS) is usually resistant to chemotherapy. We therefore determined the a, expresslon in bone marrow from patients with MDS (n = 20), primary or secondary AML (n = 50). a, and mdr., RNA transcript levels were determined by RNA- se protection assay. Western blot was performed for quantitation of a, expression and immunochemical staining was done to identify subclones of &, expressing cells using the C,,, and JSB, antibodies. Untreated primary AML were mostly negative for g&r,. High expression of a, was found in MDS (2070 %) with P,, glycoprotein detectable primarily in early myeloid progenitors, and in secondary AML (70-100 %). In y&g experiments with CHO cell lines and AML clonogenic cells demonstrated that r&, associated resistance can be circumvented by exposure with cytostatic drugs and several agents including Cicloaporin and some of its analogues, thereby restoring drug sensitivity. This study was supported by the Dutch Cancer Foundation.
FACTOR RECEPTORS
RS KACZMARSKZ Department of Haematological Medicine, King'; College School of Medicine and Dentistry, London. The binding of haemopoietic growth factors and cytokines to specific receptors triggers a cascade of intracellular events resultina in cell proliferation and differentiation. Haemopoietic growth factors are undergoing clinical trials for a number of conditions and now receotors for haemopoietic growth factors and cytokines have corns under scientific scrutiny. Receptors for IL-2a, IL-ZB, IL3, IL-4, IL-5, IL-6, IL-7, Erythropoietin, GCSF and GM-CSF have been isolated and cloned. It is ap arent that they have structural homology tg at is shared by Growth Hormone and Prolactln receptors, and this receptor group makes up the new cytokine receptor superfamily. Sequence homolo y within these receptors suggests their evo Putionary relationship. Receptors exist as high and low affinity binding forms. Binding affinity may depend on the formation of receptor heterodimers or multimers, association with other membrane proteins or differential glycosylation. Soluble receptor forms have also been described. None of the;~n~;~eptorsh~snc$ion~ as a receptor lntrlnsic protein or tyrosine tyrosine kinase activity analagous to M-CSF, PDGF, C-KIT or EGF receptors. Recently IL-2B R n to interact with the src-family ;;;a;;;np$LAX which suggests that this group of protein tyrosine kinases may serve as signal mediators. Detailed study of individual receptors holds clues to the regulation of receptor expression, ligand-receptor interactions and mechanisms involved in signal transduction. Such knowledge might explain the pleotropic effects cytokines have on different cell types and their overlap in biological functions.
HAEMOPOIESIS IN LONG-TERM MARROW CULTURE AS AN INDICATOROF EARLY MYELODYSPIASIA MF McMULLIN, C COLLETT and IAG REILLY, Department of Haematology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK. Diagnosis of myelodysplasia (MDS) is often difficult in pts with unexplained rnacrocytic anaemia (UMA). We investigated growth of long-term culture (LTBMC) of marrow from: (i)normal donors (N); (ii)pts with known MDS 8 (iii)patients with UMA. Miniature LTBMC cultured +/- 100ulml rGM-CSF were fed wkly, nonadherent (NA) cells counted 8 differentials performed. Consistent differences were noted in MDS vs N LTBMC.Cellularity of MDS LTBMC rapidly declined vs N LTBMC, stromal layers formed poorly & blast cells persisted.Changes were accentuated by rGM-CSF.ln N LTBMC, rGM-CSF: l.increased NA cells from baseline after 1 wk; 2.caused a 3-fold increase in NA cells vs LTBMC without GM-CSF; 3.inc % neuts by >5-fold vs control cultures; 4.never inc % of blasts ~5%. In MDS LTBMC, rGM-CSF: changes l-3 did not occur 8 inc % of blasts vs cultures without GM-CSF was always >lO% after 2 wks. Altered GM-CSF response in LTBMC consistently differentiated N & MDS.Results of LTBMC in 10 pts with UMA fell into 2 groups a)‘normal’ (n=5) or b) ‘MDS’ pattern. Follow up is 2-22 months: l/S ‘MDS’ pattern progressed to definite MDS & 4 are stable; 4/5 ‘normal’ pattern are stable & 1 has worsening anaemia & repeat studies show the ‘MDS’ pattern. These dala suggest this approach may be a useful test for ‘early’ MDS.
Second International
SECTION D -
Conference
CELL BIOLOGY
on Myelodysplastic
(D4) EXPRESSION
Dillerentiation Therapy in H. Phillip
Kocfflcr,
UCLA
Myelodyspbtic
Ronald Pquette,
Syndrome
M.D.,
School of Mcdicinc,
albeit not normally.
inducers of differentiation
were identified
differentiation
of Friend
crythrolcukemia
promyclocytic
leukemic
cells.
showed activity. cells.
leukemic
mice.
potential
by their capacity to induce
A bewildering
array of compounds on fresh
of active compounds were pursued in
interferons.
rdinoids,
vitamin
D,
and hexarnethylbiaacaamidc
13-cis rctinoic has been studied in at least 7 trials of IO or
more patients.
A minority
of patients responded; one investigator
data suggesting that sucessful therapy rquircs administration
of the compound.
studied in patients with MDS.
[I ,ZS(OH)J3,]
An-trans-rainoic
acid has not been
I ,25 dihydroxyvitamin
Because of hypercalccmia,
were severely limited;
differentiation
without
studies with S-azacvtidine these interesting are. ongoing.
results rquirc
several years to 10 ‘low&k’
MDS
differentiation
Initial
of about 45 % in
further study.
(4-9xl@U/wcek)
w
trials in
was given over
patients, 3/10 responsed.
larger study with this agent is rquired. than individual
D analogs that induce
arc being studied.
showed a responwrate
ar-Interfcroq
D,
trials; no major
amount of drug
new vitamin
causing hypercalcemia
has
months of
haa been used in three small MDS
responses occured. administered
identify
Initially,
cells and HL-60
of thcsc compounds including
analogs, S-azacytidine,
leukemia
MULTIDRUG
RESISTANCE
/MDR,)
of the
the ncoplastic clone
Paticnb with MDS have been treated with either one
or combinations (HMBA).
USA
A number of these were examined in
Further studies
leukemic
CA,
induce differentiation
Studies showed that in MDS,
W(LSable to differcntiatc,
MDS;
THE
P. Sonneveld, M. Schoester, P. te Boekhorst and K. Nooter Erasmus University, Department of Hematology, Rotterdam and Institute of Applied Radiobiology and Immunology, Rijswijk, The Netherlands.
Cedars Sinai Medical
Los Angeles.
Basic tenent ofdifferentiation therapy is to ncoplastic clone.
MDS
OF
GENE IN MDS.
(D2)
Center.
Syndromes
Combinations
A
of
inducing agents have not as yti proven more successful agents.
using all-m
Finally.
success in acute promyclocytic
retinoic acid should provide
effective agents for differentiation
of MDS
further impetus to cells.
(JW
(D3)
GROWTH
Over-expression of the Multidrug Resistance gene (IJ&,) is associated with clinical resistance to a variety of cytostatic agents including important antileukemic drugs, i.e., anthracyclines, vinca alkaloids and etoposide. Acute Myeloid Leukemia (AML) developing from myelodysplasia (MDS) is usually resistant to chemotherapy. We therefore determined the a, expresslon in bone marrow from patients with MDS (n = 20), primary or secondary AML (n = 50). a, and mdr., RNA transcript levels were determined by RNA- se protection assay. Western blot was performed for quantitation of a, expression and immunochemical staining was done to identify subclones of &, expressing cells using the C,,, and JSB, antibodies. Untreated primary AML were mostly negative for g&r,. High expression of a, was found in MDS (2070 %) with P,, glycoprotein detectable primarily in early myeloid progenitors, and in secondary AML (70-100 %). In y&g experiments with CHO cell lines and AML clonogenic cells demonstrated that r&, associated resistance can be circumvented by exposure with cytostatic drugs and several agents including Cicloaporin and some of its analogues, thereby restoring drug sensitivity. This study was supported by the Dutch Cancer Foundation.
FACTOR RECEPTORS
RS KACZMARSKZ Department of Haematological Medicine, King'; College School of Medicine and Dentistry, London. The binding of haemopoietic growth factors and cytokines to specific receptors triggers a cascade of intracellular events resultina in cell proliferation and differentiation. Haemopoietic growth factors are undergoing clinical trials for a number of conditions and now receotors for haemopoietic growth factors and cytokines have corns under scientific scrutiny. Receptors for IL-2a, IL-ZB, IL3, IL-4, IL-5, IL-6, IL-7, Erythropoietin, GCSF and GM-CSF have been isolated and cloned. It is ap arent that they have structural homology tg at is shared by Growth Hormone and Prolactln receptors, and this receptor group makes up the new cytokine receptor superfamily. Sequence homolo y within these receptors suggests their evo Putionary relationship. Receptors exist as high and low affinity binding forms. Binding affinity may depend on the formation of receptor heterodimers or multimers, association with other membrane proteins or differential glycosylation. Soluble receptor forms have also been described. None of the;~n~;~eptorsh~snc$ion~ as a receptor lntrlnsic protein or tyrosine tyrosine kinase activity analagous to M-CSF, PDGF, C-KIT or EGF receptors. Recently IL-2B R n to interact with the src-family ;;;a;;;np$LAX which suggests that this group of protein tyrosine kinases may serve as signal mediators. Detailed study of individual receptors holds clues to the regulation of receptor expression, ligand-receptor interactions and mechanisms involved in signal transduction. Such knowledge might explain the pleotropic effects cytokines have on different cell types and their overlap in biological functions.
HAEMOPOIESIS IN LONG-TERM MARROW CULTURE AS AN INDICATOROF EARLY MYELODYSPIASIA MF McMULLIN, C COLLETT and IAG REILLY, Department of Haematology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK. Diagnosis of myelodysplasia (MDS) is often difficult in pts with unexplained rnacrocytic anaemia (UMA). We investigated growth of long-term culture (LTBMC) of marrow from: (i)normal donors (N); (ii)pts with known MDS 8 (iii)patients with UMA. Miniature LTBMC cultured +/- 100ulml rGM-CSF were fed wkly, nonadherent (NA) cells counted 8 differentials performed. Consistent differences were noted in MDS vs N LTBMC.Cellularity of MDS LTBMC rapidly declined vs N LTBMC, stromal layers formed poorly & blast cells persisted.Changes were accentuated by rGM-CSF.ln N LTBMC, rGM-CSF: l.increased NA cells from baseline after 1 wk; 2.caused a 3-fold increase in NA cells vs LTBMC without GM-CSF; 3.inc % neuts by >5-fold vs control cultures; 4.never inc % of blasts ~5%. In MDS LTBMC, rGM-CSF: changes l-3 did not occur 8 inc % of blasts vs cultures without GM-CSF was always >lO% after 2 wks. Altered GM-CSF response in LTBMC consistently differentiated N & MDS.Results of LTBMC in 10 pts with UMA fell into 2 groups a)‘normal’ (n=5) or b) ‘MDS’ pattern. Follow up is 2-22 months: l/S ‘MDS’ pattern progressed to definite MDS & 4 are stable; 4/5 ‘normal’ pattern are stable & 1 has worsening anaemia & repeat studies show the ‘MDS’ pattern. These dala suggest this approach may be a useful test for ‘early’ MDS.