Search PubMed⌕ Search

Biomedical subjects

Teru Hideshima

Publications and source records attributed to Teru Hideshima.

At least 127 records · Page 7Linked to original sources
PubMed2002

Targeting p38 MAPK inhibits multiple myeloma cell growth in the bone marrow milieu.

p38 mitogen-activated protein kinase (MAPK) is a member of the MAPK family which is activated by cytokines and growth factors, but its role in pathogenesis of multiple myeloma (MM) is unknown. In this study, we demonstrate that the specific p38 MAPK inhibitor VX-745 inhibits interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF) secretion in bone marrow stromal cells (BMSCs), without affecting their viability. Tumor necrosis factor alpha (TNF-alpha)-induced IL-6 secretion in BMSCs is also inhibited by VX-745. Importantly, VX-745 inhibits both MM cell proliferation and IL-6 secretion in BMSCs triggered by adherence of MM cells to BMSCs, suggesting that it can inhibit paracrine MM cell growth in the BM milieu and overcome cell adhesion-related drug resistance. These studies therefore identify p38 MAPK as a novel therapeutic target to overcome drug resistance and improve patient outcome in MM.

Bone Marrow Cells↗
PubMed2002

Proteasome inhibitor PS-341 inhibits human myeloma cell growth in vivo and prolongs survival in a murine model.

The proteasome is a ubiquitous and essential intracellular enzyme that degrades many proteins regulating cell cycle, apoptosis, transcription, cell adhesion,angiogenesis, and antigen presentation. We have shown recently that the proteasome inhibitor PS-341 inhibits growth, induces apoptosis, and overcomes drug resistance in human myeloma cells in vitro. In this study, we examined the efficacy, toxicity, and in vivo mechanism of action of PS-341 using a human plasmacytoma xenograft mouse model. One hundred immunodeficient (beige-nude-xid) mice were used in two independent experiments. The mice were injected s.c. with 3 x 10(7) RPMI-8226 myeloma cells. When tumors became measurable (9.2 days; range, 6-13 days after tumor injection), mice were assigned to treatment groups receiving PS-341 0.05 mg/kg (n = 13), 0.1 mg/kg (n = 15), 0.5 mg/kg (n = 14), or 1.0 mg/kg (n = 14) twice weekly via tail vein, or to control groups (n = 13) receiving the vehicle only. Significant inhibition of tumor growth, even with some complete tumor regression, was observed in PS-341-treated mice. The median overall survival was also significantly prolonged compared with controls (30 and 34 days for high dose-treated mice versus 14 days for controls; P < 0.0001). PS-341 was well tolerated up to 0.5 mg/kg, but some mice treated at 1.0 mg/kg became moribund and lost weight. Analysis of tumors harvested from treated animals showed that PS-341 induced apoptosis and decreased angiogenesis in vivo. These studies therefore demonstrate that PS-341 has significant in vivo antimyeloma activity at doses that are well tolerated in a murine model, confirming our in vitro data and further supporting the early clinical promise of PS-341 to overcome drug resistance and improve patient outcome.

Animals↗
PubMed2002

The vascular endothelial growth factor receptor tyrosine kinase inhibitor PTK787/ZK222584 inhibits growth and migration of multiple myeloma cells in the bone marrow microenvironment.

Our prior studies show that multiple myeloma (MM) cell lines and patient cells express high-affinity vascular endothelial growth factor (VEGF) receptor (VEGFR) Flt-1 but not Flk-1/KDR. Moreover, these studies have shown that VEGF induces proliferation and migration of MM cells, and we have begun to delineate the signaling cascades mediating those sequelae. In this study, we examined the activity of PTK787/ZK 222584 (PTK787), a molecule designed to bind specifically to the tyrosine kinase domain of VEGFR and inhibit angiogenesis. We show that PTK787 acts both directly on MM cells and in the bone marrow microenvironment. Specifically, PTK787 (1-5 micro M) inhibits proliferation of MM cells by 50%, as assayed by [(3)H]thymidine uptake. This effect of PTK787 is dose dependent in both MM cell lines and patient cells that are both sensitive and resistant to conventional therapy. PTK787 enhances the inhibitory effect of dexamethasone on growth of MM cells and can overcome the protective effect of interleukin 6 (IL-6) against dexamethasone-induced apoptosis. PTK787 (1 micro M) also blocks VEGF-induced migration of MM cells across an extracellular matrix. Importantly, PTK787 also inhibits the increased MM cell proliferation and increased IL-6 and VEGF secretion in cultures of MM cells adherent to bone marrow stem cells. These findings therefore demonstrate that PTK787 both acts directly on MM cells and inhibits paracrine IL-6-mediated MM cell growth in the bone marrow milieu. The demonstrated anti-MM activity of PTK787, coupled with its antiangiogenic effects, provides the framework for clinical trials of this agent to overcome drug resistance and improve outcome in MM.

Bone Marrow↗
PubMed2002

Activation of NF-kappaB and upregulation of intracellular anti-apoptotic proteins via the IGF-1/Akt signaling in human multiple myeloma cells: therapeutic implications.

Interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1) promote the proliferation of multiple myeloma (MM) cells and protect them against dexamethasone (Dex)-induced apoptosis. We have previously shown that Apo2 ligand/TNF-Related apoptosis inducing ligand (Apo2L/TRAIL) induces apoptosis of MM cells, including cells either sensitive or resistant to Dex and cytotoxic drugs, and overcomes the growth and survival effect of IL-6; conversely, NF-kappaB transcriptional activity attenuates their Apo2L/TRAIL-sensitivity. In the current study, we demonstrate that IGF-1 stimulates sustained activation of NF-kappaB and Akt; induces phosphorylation of the FKHRL-1 Forkhead transcription factor; upregulates a series of intracellular anti-apoptotic proteins including FLIP, survivin, cIAP-2, A1/Bfl-1, and XIAP; and decreases Apo2L/TRAIL-sensitivity of MM cells. In contrast, IL-6 does not cause sustained NF-kappaB activation, induces less pronounced Akt activation and FKHRL-1 phosphorylation than IGF-1, and increases the expression of only survivin. Forced overexpression of constitutively active Akt in MM-1S cells reduced their sensitivity to Apo2L/TRAIL and to doxorubicin (Doxo). In contrast, the Akt inhibitor IL-6-Hydroxymethyl-chiro-inositol 2-(R)-2-O-methyl-3-O-octadecylcarbonate induced cell death of both Dex- and Doxo-sensitive and -resistant cells; opposed the protective effect of constitutive Akt activity against Apo2L/TRAIL; and abrogated the NF-kappaB activation, increase of anti-apoptotic proteins and protection against Apo2L/TRAIL induced by IGF-1. These findings therefore define an important role of the Akt pathway in modulating tumor cell responsiveness to Apo2L/TRAIL, delineate molecular mechanisms for the survival effects of IGF-1, and characterize differential pathophysiologic sequelae of IGF-1 vs IL-6 on MM cells. Importantly, they provide the basis for future clinical trials in MM combining conventional or novel agents with strategies designed to neutralize IGF-1.

Apoptosis↗
PubMed2002

Absence of biologically important Kaposi sarcoma-associated herpesvirus gene products and virus-specific cellular immune responses in multiple myeloma.

Kaposi sarcoma-associated herpesvirus (KSHV) has been associated with several diseases, but the association between KSHV and multiple myeloma (MM) remains controversial. To address this issue, we studied patients with MM for the presence of viral RNA transcripts as well as KSHV-specific cellular immune responses. Highly sensitive reverse transcription-polymerase chain reaction assays for detection of viral transcripts of KSHV open reading frame (ORF) 26, ORF72, and ORF74 did not detect viral gene transcripts in long-term cultures of bone marrow stromal cells from 23 patients with MM. Moreover, sensitive assays for KSHV ORF65-specific and ORF73-specific cytotoxic T-lymphocyte (CTL) activity that readily and routinely detect CTLs specific for ORF65 and ORF73 in patients positive for human immunodeficiency virus and KSHV did not show any specific responses in 16 patients with MM, despite the presence of positive Epstein-Barr virus-specific CTLs in all cases. These data therefore do not show a biologically important association between ongoing KSHV infection and MM.

Antigens, Viral↗
PubMed2002

Cytokines modulate telomerase activity in a human multiple myeloma cell line.

Telomerase is a ribonucleoprotein DNA polymerase that elongates the telomeres of chromosomes to compensate for losses that occur with each round of DNA replication and maintain chromosomal stability. Interleukin 6 (IL-6) and insulin-like growth factor 1 (IGF-1) are proliferative and survival factors for human multiple myeloma (MM) cells. To date, however, the effects of IGF-1 and IL-6 on telomerase activity and associated sequelae in MM cells have not been characterized. In this study, we evaluated the effects of IGF-1 and IL-6 on telomerase activity in MM cell lines (MM.1S, U266, and RPMI 8226), as well as patient MM cells. We show that these cytokines up-regulate telomerase activity without alteration of human telomerase reverse transcriptase (hTERT) protein expression. We also demonstrate that increased telomerase activity triggered by these cytokines is mediated by phosphatidylinositol 3'-kinase (PI3k)/Akt/nuclear factor kappaB (NFkappaB) signaling. We confirm involvement of PI3k/Akt/NFkappaB signaling because the PI3k inhibitors wortmannin and LY294002 or the inhibitor of NFkappaB (IkappaB) kinase inhibitor PS-1145 block constitutive and cytokine-induced up-regulation of telomerase activity. Furthermore, we show that dexamethasone (Dex) reduces telomerase activity through the inhibition of hTERT expression before the induction of apoptosis. Importantly, IGF-1 and IL-6 abrogate Dex-induced down-regulation of telomerase activity and apoptosis. The protective effect of those cytokines against Dex-induced down-regulation of telomerase activity is blocked by both wortmannin and PS-1145, whereas the protection against Dex-induced apoptosis is blocked by wortmannin but not PS-1145. Therefore, our results demonstrate that telomerase activity is related not only to transcriptional regulation of hTERT by NFkappaB but also to posttranscriptional regulation because of phosphorylation of hTERT by Akt kinase. These studies therefore demonstrate that telomerase activity is associated with cell growth, survival, and drug resistance in MM cells.

Apoptosis↗
PubMed2002

Apoptotic signaling induced by immunomodulatory thalidomide analogs in human multiple myeloma cells: therapeutic implications.

Thalidomide (Thal) achieves responses even in the setting of refractory multiple myeloma (MM). Although increased angiogenesis in MM bone marrow and the antiangiogenic effect of Thal formed the empiric basis for its use in MM, we have shown that Thal and its immunomodulatory analogs (IMiDs) directly induce apoptosis or growth arrest of MM cells, alter adhesion of MM cells to bone marrow stromal cells, inhibit the production of cytokines (interleukin-6 and vascular endothelial growth factor) in bone marrow, and stimulate natural killer cell anti-MM immunity. In the present study, we demonstrate that the IMiDs trigger activation of caspase-8, enhance MM cell sensitivity to Fas-induced apoptosis, and down-regulate nuclear factor (NF)-kappa B activity as well as expression of cellular inhibitor of apoptosis protein-2 and FLICE inhibitory protein. IMiDs also block the stimulatory effect of insulinlike growth factor-1 on NF-kappa B activity and potentiate the activity of TNF-related apoptosis-inducing ligand (TRAIL/Apo2L), dexamethasone, and proteasome inhibitor (PS-341) therapy. These studies both delineate the mechanism of action of IMiDs against MM cells in vitro and form the basis for clinical trials of these agents, alone and coupled with conventional and other novel therapies, to improve outcome in MM.

Adjuvants, Immunologic↗
PubMed2002

Biologic sequelae of nuclear factor-kappaB blockade in multiple myeloma: therapeutic applications.

The transcription factor nuclear factor-kappaB (NF-kappaB) confers significant survival potential in a variety of tumors. Several established or novel anti-multiple myeloma (anti-MM) agents, such as dexamethasone, thalidomide, and proteasome inhibitors (PS-341), inhibit NF-kappaB activity as part of their diverse actions. However, studies to date have not delineated the effects of specific inhibition of NF-kappaB activity in MM. We therefore investigated the effect of SN50, a cell-permeable specific inhibitor of NF-kappaB nuclear translocation and activity, on MM cells. SN50 induced apoptosis in MM cell lines and patient cells; down-regulated expression of Bcl-2, A1, X-chromosome-linked inhibitor-of-apoptosis protein (XIAP), cellular inhibitor-of-apoptosis protein 1 (cIAP-1), cIAP-2, and survivin; up-regulated Bax; increased mitochondrial cytochrome c release into the cytoplasm; and activated caspase-9 and caspase-3, but not caspase-8. We have previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) is present locally in the bone marrow microenvironment and induces NF-kappaB-dependent up-regulation of adhesion molecules on both MM cells and bone marrow stromal cells, with resultant increased adhesion. In this study, TNF-alpha alone induced NF-kappaB nuclear translocation, cIAP-1 and cIAP-2 up-regulation, and MM cell proliferation; in contrast, SN50 pretreatment sensitized MM cells to TNF-alpha-induced apoptosis and cleavage of caspase-8 and caspase-3, similar to our previous finding of SN50-induced sensitization to apoptosis induced by the TNF-alpha family member TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L. Moreover, SN50 inhibited TNF-alpha-induced expression of another NF-kappaB target gene, intercellular adhesion molecule-1. Although the p38 inhibitor PD169316 did not directly kill MM cells, it potentiated the apoptotic effect of SN50, suggesting an interaction between the p38 and NF-kappaB pathways. Our results therefore demonstrate that NF-kappaB activity in MM cells promotes tumor-cell survival and protects against apoptotic stimuli. These studies provide the framework for targeting NF-kappaB activity in novel biologically based therapies for MM.

Apoptosis↗
PubMed2002

NF-kappa B as a therapeutic target in multiple myeloma.

We have shown that thalidomide (Thal) and its immunomodulatory derivatives (IMiDs), proteasome inhibitor PS-341, and As(2)O(3) act directly on multiple myeloma (MM) cells and in the bone marrow (BM) milieu to overcome drug resistance. Although Thal/IMiDs, PS-341, and As(2)O(3) inhibit nuclear factor (NF)-kappaB activation, they also have multiple and varied other actions. In this study, we therefore specifically address the role of NF-kappaB blockade in mediating anti-MM activity. To characterize the effect of specific NF-kappaB blockade on MM cell growth and survival in vitro, we used an IkappaB kinase (IKK) inhibitor (PS-1145). Our studies demonstrate that PS-1145 and PS-341 block TNFalpha-induced NF-kappaB activation in a dose- and time-dependent fashion in MM cells through inhibition of IkappaBalpha phosphorylation and degradation of IkappaBalpha, respectively. Dexamethasone (Dex), which up-regulates IkappaBalpha protein, enhances blockade of NF-kappaB activation by PS-1145. Moreover, PS-1145 blocks the protective effect of IL-6 against Dex-induced apotosis. TNFalpha-induced intracellular adhesion molecule (ICAM)-1 expression on both RPMI8226 and MM.1S cells is also inhibited by PS-1145. Moreover, PS-1145 inhibits both IL-6 secretion from BMSCs triggered by MM cell adhesion and proliferation of MM cells adherent to BMSCs. However, in contrast to PS-341, PS-1145 only partially (20-50%) inhibits MM cell proliferation, suggesting that NF-kappaB blockade cannot account for all of the anti-MM activity of PS-341. Importantly, however, TNFalpha induces MM cell toxicity in the presence of PS-1145. These studies demonstrate that specific targeting of NF-kappaB can overcome the growth and survival advantage conferred both by tumor cell binding to BMSCs and cytokine secretion in the BM milieu. Furthermore, they provide the framework for clinical evaluation of novel MM therapies based upon targeting NF-kappaB.

Antineoplastic Agents↗
PubMed2002

Identification of genes regulated by dexamethasone in multiple myeloma cells using oligonucleotide arrays.

Our previous studies have characterized Dexamethasone (Dex)-induced apoptotic signaling pathways in multiple myeloma (MM) cells; however, related transcriptional events are not fully defined. In the present study, gene expression profiles of Dex-treated MM cells were determined using oligonucleotide arrays. Dex triggers early transient induction of many genes involved in cell defense/repair-machinery. This is followed by induction of genes known to mediate cell death and repression of growth/survival-related genes. The molecular and genetic alterations associated with Dex resistance in MM cells are also unknown. We compared the gene expression profiles of Dex-sensitive and Dex-resistant MM cells and identified a number of genes which may confer Dex-resistance. Finally, gene profiling of freshly isolated MM patient cells validates our in vitro MM cell line data, confirming an in vivo relevance of these studies. Collectively, these findings provide insights into the basic mechanisms of Dex activity against MM, as well as mechanisms of Dex-resistance in MM cells. These studies may therefore allow improved therapeutic uses of Dex, based upon targeting genes that regulate MM cell growth and survival.

Apoptosis↗
PubMed2002

beta-lapachone, a novel plant product, overcomes drug resistance in human multiple myeloma cells.

OBJECTIVE: To evaluate the anti-tumor potential of beta-lapachone in multiple myeloma (MM) cell lines (U266, RPMI8226, and MM.1S); MM cell lines resistant to dexamethasone (MM.1R), melphalan (RPMI8226/LR5), doxorubicin (RPMI8226/DOX40), and mitoxantrone (RPMI8226/ MR20); and MM cells from patients (MM1-MM4). MATERIALS AND METHODS: Cytotoxicity of beta-lapachone was assessed by MTT and [3H]-thymidine uptake assays. Apoptosis was analyzed using propidium iodide staining, DNA fragmentation, TUNEL assay, caspase-9 colorimetric assay, and immunoblotting for caspase-3, poly (ADP-ribose) polymerase (PARP), and caspase-8 cleavage products. Paracrine growth of MM cells was assessed by [3H]-thymidine uptake in cultures of bone marrow stromal cells (BMSCs) and MM cells. Interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) secretion in the culture supernatants was measured by specific enzyme-linked immunosorbent assays (ELISAs). RESULTS: beta-lapachone showed significant cytotoxicity in MM cells (IC(50): 4-8 microM). In contrast, normal peripheral blood mononuclear cells (PBMCs) and BMSCs from MM patients were relatively resistant (IC(50): 8-16 microM). IL-6 did not protect against beta-lapachone-induced apoptosis in MM.1S cells, and dexamethasone showed additive cytotoxicity. beta-lapachone also decreased binding of MM.1S cells to BMSCs; abrogated IL-6 and VEGF secretion triggered by adhesion of BMSCs to MM.1S cells; reduced proliferation of MM.1S cells adherent to BMSCs; and decreased intracellular adhesion molecule-1 (ICAM-1) expression on MM.1S cells. Furthermore, beta-lapachone induced typical PARP cleavage, increased caspase-9 proteolytic activity, and activation of caspase-3, without activation of caspase-8 in U266 cells. CONCLUSION: These studies provide a framework for clinical evaluation of beta-lapachone to improve the outcome for patients with MM.

Antibiotics, Antineoplastic↗
PubMed2002

Molecular mechanisms of novel therapeutic approaches for multiple myeloma.

Multiple myeloma remains largely incurable despite conventional and high-dose therapies, and so novel biologically based treatment approaches are urgently required. Recent studies have characterized the molecular mechanisms by which multiple myeloma cell-host bone-marrow interactions regulate tumour cell growth, survival and migration in the bone-marrow microenvironment. These studies have not only enhanced our understanding of disease pathogenesis, but have also provided the framework for a new treatment model that targets the multiple myeloma cell in its bone-marrow microenvironment to overcome drug resistance and improve patient outcome.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

Novel biologically based therapeutic strategies in myeloma.

Multiple myeloma remains incurable despite advances in conventional chemotherapy and wider applicability of high dose chemotherapy with single and/or tandem autologous peripheral blood stem cell transplantation. Although a complete remission rate of 41% and an event-free survival of 43 months have been reported after tandem transplantation, it is highly unlikely that further improvements in the outcome of multiple myeloma will be achieved by escalating cytotoxic chemotherapy alone. Novel biologically based therapies are therefore urgently required. Targeted therapeutic approaches based on: identification of genetic abnormalities in malignant plasma cells; interrupting growth of myeloma cells; triggering apoptotic signaling cascades in tumor cells; modulating growth and survival of multiple myeloma cells in the bone marrow microenvironment, i.e. angiogenesis and cytokine networks; enhancing allogeneic and autologous antimyeloma immunity; and characterizing newer myeloma antigens for serotherapy are under development. These therapies offer great promise, used alone/or in combination with conventional treatment approaches, to improve the outcome in this disease in newly diagnosed/refractory or relapsed patients with multiple myeloma.

Antineoplastic Agents↗
PubMed2002

Thalidomide: emerging role in cancer medicine.

Thalidomide--removed from widespread clinical use by 1962 because of severe teratogenicity--has antiangiogenic and immunomodulatory effects, including the inhibition of tumor necrosis alpha factor. It has now returned to practice as an effective oral agent in the management of various disease states including erythema nodosum leprosum, for which it was approved by the U.S. Food and Drug Administration in 1998, and more recently certain malignancies, including multiple myeloma. Although thalidomide's mechanism of action remains incompletely understood, considerable insight has been generated by extensive preclinical studies in multiple myeloma. Moreover, clinical trials have confirmed benefit in relapsed disease, and the role of thalidomide in treating newly diagnosed patients is currently under study. Its use in other tumors is under evaluation, with promise in renal cell carcinoma, prostate cancer, glioma, and Kaposi's sarcoma. Activity has also been demonstrated in chronic graft-versus-host disease and in symptom relief as part of palliative care.

Adjuvants, Immunologic↗
PubMed2002

Telomerase inhibitors as anticancer therapy.

Telomerase inhibitors have been touted as a novel cancer specific therapy, as most tumor cells have high expression of telomerase, whereas most normal somatic cells express low or undetectable levels of telomerase. Continued proliferation of tumor cells requires activation of telomerase to maintain chromosomal stability and extend life span, because telomerase elongates telomere length and rewinds the cellular mitotic clock. Conversely, shortening of telomeres by inhibition of telomerase activity induces growth arrest (senescence) and apoptosis in tumor cells. Moreover, it has been reported that inhibition of telomerase increases the susceptibility of tumor cells to apoptosis induced by anticancer agents. Thus, telomerase inhibitors could be used as an adjuvant with conventional therapy. However, there are also several potential limitations of telomerase inhibition as a therapeutic strategy. For example, there is a lag phase between telomerase inhibition and telomere shortening, with growth arrest and cell death. In this review, we will discuss the basic biology of telomeres and telomerase as a platform for the development of treatments based upon inhibition of telomerase activity.

Animals↗
PubMed2002

The biological sequelae of stromal cell-derived factor-1alpha in multiple myeloma.

Stromal cell-derived factor (SDF)-1alpha mediates migration of normal hematopoietic stem cells, but its role in hematological malignancies is undefined. In this study, we detected SDF-1alpha in bone marrow (BM) plasma from 10 patients with MM (multiple myeloma; 2.6 +/- 1.5 ng/ml) and BM stromal cell culture supernatants from 5 patients with MM (0.6 +/- 0.2 ng/ml). We show that SDF-1alpha promotes proliferation, induces migration, and protects against dexamethasone-induced apoptosis in MM cells, but these effects are only modest. In MM cell lines and patient MM cells, SDF-1alpha induces phosphorylation of p42/44 mitogen-activated protein kinase, as well as Akt and its downstream target Bad, and also activates nuclear factor-kappaB. In the BM milieu, SDF-1alpha up-regulates secretion of interleukin 6 and vascular endothelial growth factor in BM stromal cells, which promote tumor cell growth, survival, and migration. These data demonstrate that SDF-1alpha promotes growth, migration and drug resistance of MM cells in the BM microenvironment, but these effects are only modest, SDF-1alpha therefore does not represent a target for novel therapeutics in this disease.

Apoptosis↗
PubMed2002

Arsenic trioxide inhibits growth of human multiple myeloma cells in the bone marrow microenvironment.

Multiple myeloma (MM) remains incurable with current therapies, and novel biologically based therapies are urgently needed. Thalidomide and its analogues, as well as proteasome inhibitors, are examples of such novel agents that target both the myeloma cell and its microenvironment and can overcome classical drug resistance. In this study we demonstrate that arsenic trioxide (As2O3) mediates anti-MM activity both directly on tumor cells and indirectly by inhibiting production of myeloma growth and survival factors in the bone marrow (BM) microenvironment. Specifically, As2O3 at clinically achievable levels (2-5 microM) induces apoptosis even of drug-resistant MM cell lines and patient cells via caspase-9 activation, enhances the MM cell apoptosis induced by dexamethasone, and can overcome the antiapoptotic effects of interleukin 6. As2O3 also acts in the BM microenvironment to decrease MM cell binding to BM stromal cells, inhibits interleukin 6 and vascular endothelial growth factor secretion induced by MM cell adhesion, and blocks proliferation of MM cells adherent to BM stromal cells. These studies provide the rationale for clinical trials of As2O3, either alone or together with dexamethasone, to overcome classical drug resistance and improve outcome in patients with MM.

Antineoplastic Agents↗