Haematologica 2003 - Supplements

HDAC inhibition in MM triggers a distinct transcriptional
signature hallmarked by suppression of pathways critical for
tumor cell proliferation, survival and drug resistance, including
downregulation of insulin-like growth factor (IGF) / IGF-1
receptor (IGF-1R) and interleukin-6 receptor (IL-6R) signaling
cascades; suppression of anti-apoptotic molecules (e.g. caspase
inhibitors); oncogenes (e.g. myb, maf, pim-1, Axl, Polo and
Aurora kinases, abl, vav, PAK-1, ASK); DNA synthesis or repair
enzymes; transcription factors (e.g. XBP-1, E2F-1);
nucleocytoplasmic transport regulators; and adhesion molecules
(e.g. RHAMM, intergrins) implicated in MM pathophysiology.
SAHA treatment upregulates p53 transcriptional activity,
represses the activity of HIF-1á and NF-êB, suppresses 26S
proteasome subunits and proteasome activity, but does not trigger
major heat shock protein upregulation, in contrast to pronounced
stress responses generated by treatment of MM cells with other
anti-tumor agents, e.g. proteasome inhibitors. Importantly, SAHA
enhances MM cell sensitivity to other anti-MM agents, including
dexamethasone, cytotoxic chemotherapy, as well as thalidomide
analogs, proteasome inhibitors or hsp90 inhibitors. SAHA
treatment does not indiscriminately suppress or activate gene
transcription: it modulates expression of a wide constellation of
molecular targets, which correspond, however, to highly specific
functional clusters, with known direct or indirect involvement in
tumorigenesis and/or proliferation, survival and drug-resistance
of MM cells, specifically, or malignant cells, in general. Our
studies indicate that HDAC function is critical for MM cells by
actively maintaining a transcriptional program indispensable for
their uncontrolled proliferation and/or inappropriate resistance to
proapoptotic stimuli. The pleiotropic anti-tumor effects of SAHA,
its ability to enhance the anti-MM activity of multiple
conventional or novel agents and, importantly, the fact that it was
bioavailable, well-tolerated and achieved objective responses
after oral administration in phase I clinical trials, provide the
framework for future clinical applications of SAHA to improve
patient outcome in MM.
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GENE EXPRESSION AND PROTEOMIC PROFILING OF
DRUG-TREATED MULTIPLE MYELOMA (MM) CELLS:
MECHANISMS OF DRUG RESPONSIVENESS VS.
RESISTANCE AND RATIONALE FOR DESIGN OF
NOVEL COMBINATION THERAPIES FOR MM
Constantine S. Mitsiades1,2, Nicholas Mitsiades1,2, Ciaran
J. McMullan1,2, Charles Bailey3, Xuesong Gu3, Marie
Joseph3, Galinos Fanourakis1,2, Nikhil C. Munshi1,2,
Vassiliki Poulaki4, Towia A. Liberman3 and Kenneth C.
Anderson1,2.
1. Jerome Lipper Multiple Myeloma Center, Department of Medical
Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts,
USA; 2. Department of Medicine, Harvard Medical School, Boston,
Massachusetts, USA; 3. Harvard Institutes of Medicine, Beth Israel
Deaconess Medical Center, Boston, Massachusetts,USA; 4.
Massachusetts Eye and Ear Infirmary, Harvard Medical School,
234 Charles Street, Boston,Massachusetts, USA.
The ongoing expansion of the therapeutic armamentarium for
multiple myeloma (MM) with an extensive series of novel
biologically-based treatment strategies poses the translational
dilemma of how such agents should be optimally combined
clinically with other conventional or novel therapies for MM.
Indiscriminate testing of all possible treatment combinations is
not feasible at either clinical or pre-clinical level, highlighting the
need for rational design of anti-MM combination therapies based
on comprehensive molecular profiling (at the gene expression and
proteomic level) of individual agents. We have performed such
transcriptional and proteomic profiling of MM cells treated ex
vivo with conventional therapies (Dex, Doxo); as well as novel
agents with pre-clinical and/or clinical evidence of anti-MM
activity, including proteasome inhibitor (PS-341),
immunomodulatory thalidomide derivatives (IMiDs), inhibitors
of the hsp90 chaperone (17-AAG), histone deacetylase inhibitors
(SAHA), thiazolidinedione (TZD) PPAR-ã agonists (ciglitazone),
and inhibitors of IGF-1 receptor (IGF-1R) activity, and
HMGCoA inhibitors (lovastatin). The molecular profiling was
coupled with bio-informatic analyses, including hierarchical
clustering, functional clustering and relevance network analyses,
as well as with confirmatory mechanistic studies. These profiling
studies documented overlapping molecular features of such novel
classes of agents, including effect of PS-341, hsp90 inhibitors and
IGF-1R inhibition on the NF-êB pathway and its activity; and
decreased expression of inhibitors of apoptosis (IAPs) conferred
by treatment with PS-341, 17-AAG, IGF-1R inhibitors, SAHA or
TZDs. On the other hand, distinct molecular sequelae were
induced by certain agents e.g. hsp90 inhibitors induced depletion
of intracellular levels of several kinases implicated in
growth/survival cascades (IGF-1R, Akt, Raf, IKK-á), while
SAHA suppressed expression of key heat shock proteins (hsp)
and regulators of translation. These studies provide a framework
for combination treatments to enhance anti-MM activity. For
example, PS-341 induced pronounced upregulation of heat shock
protein (hsp) transcription and protein expression, in an apparent
cellular response to counteract the stress of accumulating
intracellular undegraded proteins, by promoting their enhanced
chaperoning. This suggests that upregulation of hsp's may
modulate sensitivity to PS-341, and that agents which abrogate
the chaperoning function of key hsp's, such as the hsp90 inhibitor
geldanamycin and its analogs, may increase MM cell sensitivity
and/or overcome resistance to PS-341 or other agents (e.g. Doxo,
Dex) which also upregulate hsp expression, in our studies. These
studies on drug-induced molecular profiling therefore provide a
framework for rational design of anti-MM combination therapies
including therapies which independently target distinct proapoptotic
pathways, inhibit key proliferative/anti-apoptotic
pathways at distinct molecular levels, affording more effective
overall blockade of the targeted pathway, while capitalizing on
the use of certain agents to abrogate anti-apoptotic mechanisms
attenuating response to other drugs.
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