Proteasome Inhibitors Block Myeloma-Induced Osteocyte Death in Vitro and in Vivo in Multiple Myeloma Patients

Abstract Abstract 3978 Multiple myeloma (MM) is characterized by a severe unbalanced and uncoupling bone remodeling leading to osteolysis. We have recently shown that osteocytes are involved in MM-induced osteolysis through an increased cell death. Accordingly MM patients are characterized by a reduced number of viable osteocytes related to the presence of bone lesions. Proteasome inhibitors currently used in the treatment of MM are able to stimulate osteoblast formation but their potential effects on osteocyte death are not known and have been investigated in this study both in vitro and in vivo. Osteocytic MLO-Y4 cells or human pre-osteocytic HOB-01 cells were co-cultured for 48 hours in the presence or absence of the human myeloma cell lines (HMCLs) JJN3 or RPMI-8226 placed in a transwell insert. A significantly reduction of ostecyte viability was observed (median percent reduction of MLO-Y4 viability: -16% and -30%, respectively). The treatment for 12–24 hours with Bortezomib (BOR) (2nM) or other proteasome inhibitors such as MG262 (10nM) or MG132 (100nM) significantly blunted MLO-Y4 and HOB-01 cell death. Similarly, Dexamethasone (DEX)-induced MLO-Y4 apoptosis, obtained at pharmacological doses (10−4−10−5 M), was significantly reduced by the treatment with proteasome inhibitors. To translate our in vitro data into a clinical perspective we performed a retrospective histological evaluation on bone biopsies of a cohort of 40 newly diagnosis MM patients (24 male and 16 female, median age: 68 years) 34 of them with symptomatic MM and 6 with smoldering MM (SMM). The 58% of patients with symptomatic MM have evidence of osteolytic lesions at the X-rays survey. Bone biopsies were obtained in both symptomatic MM and SMM at diagnosis and after an average time of 12 months of treatment or observation, respectively. The 68% of patients with symptomatic MM were treated with a BOR-based regimen while 42% do not. Moreover the 58% of MM patients received DEX and the 59% Thalidomide (TAL). Zoledronic acid (ZOL) was infused monthly in the 60% of MM patients. Osteocyte viability was evaluated in a total of 500 lacunae per histological sections, corresponds to the total number of osteocyte lacunae in the bone biopsies. The number of viable osteocytes and the number of degenerated or apoptotic osteocytes and empty lacunae have been evaluated. In patients with SMM no significant change was observed in the number of viable osteocytes in the two histological evaluations carried out (median percent change: +1.2, p=0.68, NS). In symptomatic MM patients the mean percent change of the osteocyte viability was not correlated with the response rate to treatment (R2 0.01, p=NS). A significant increase of the number of viable osteocytes was demonstrated in MM patients treated with BOR-based regimen as compared to those treated without BOR (% median increase of osteocyte viability: +6% vs. +1.30%, Mann-Whitney test: p=0.017). Patients treated with BOR alone showed the highest increase of osteocyte viability that was statistical significant in comparison with that observed either in patients treated without BOR (+11.6% vs. +1.3%, p=0.0019) or in those treated with BOR plus DEX (+11.6% vs. +4.4%, p=0.01). On the contrary, no significant difference was observed in patients treated with TAL than in those treated without TAL (p= 0.7, NS) as well as patients treated with ZOL compared to those untreated showed no significant difference in the number of viable osteocytes (p=0.18, NS). To confirm the role of the different drug treatment on the osteocyte viability we perform a multiple regression non-parametric analysis showing that BOR had a significant positive impact on osteocyte viability (p=0.042) whereas ZOL and TAL have not (p>0.2,NS) and it counterbalanced the negative effect of DEX treatment (p=0.035). In conclusion our in vitro and in vivo data suggest the proteasome inhibitors block osteocyte death induced by MM cells could have a positive impact on bone integrity in MM patients. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Myeloma-Induced Osteocyte Death Was Blunted By Proteasome Inhibitors Through The Modulation Of Autophagy

Blood ◽

10.1182/blood.v122.21.3096.3096 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3096-3096

Author(s):

Denise Toscani ◽

Carla Palumbo ◽

Benedetta Dalla Palma ◽

Marina Bolzoni ◽

Marzia Ferretti ◽

...

Keyword(s):

Cell Death ◽

Confocal Microscopy ◽

Cell Lines ◽

Proteasome Inhibitors ◽

Autophagic Cell Death ◽

Histological Evaluation ◽

Significant Difference ◽

Bone Biopsies ◽

Osteocyte Death

Abstract Osteocytes are critical in the maintenance of bone integrity regulating bone remodeling through the cell death and autophagy, a cellular process stress-induced to prolong cell survival but when induced excessively can cause cell death. Recently we have demonstrated that an increased osteocyte death is involved in multiple myeloma (MM)-induced osteolysis. However the mechanisms involved in this process as well as the effect of the proteasome inhibitors able to stimulate bone formation are not known and have been investigated in this study. Firstly the effect of the proteasome inhibitors BOR and MG262 on osteocyte viability was evaluated in vitro in murine osteocytic cell line MLO-Y4 and in the human pre-osteocytic one HOB-01. Both cell lines were co-coltured for 48 hours in the presence or absence of the human myeloma cell lines (HMCLs) RPMI8226 and JJN3, placed in a traswell insert. The treatment for 12-24 hours with (BOR) (2nM) and MG262 (10nM) significantly blunted MLO-Y4 and HOB-01 cell death. In addition, dexamethasone (DEX)-induced MLO-Y4 apoptosis, obtained at high doses (10-5-10-6 M), was reduced by the treatment with proteasome inhibitors. Interestingly, we found that PTH short-term treatment potentiated the in vitro effects of proteasome inhibitors on DEX-induced osteocyte death. To evaluate the presence of autophagy in osteocytes, we checked the expression of the autophagic marker LC3 both by confocal microscopy and western blot analysis in the co-colture system with MLO-Y4 and RPMI-8226. Prevalence of autophagic cell death and in a lesser extent apoptosis was observed in this system. BOR increased the basal level of LC3 indicating a pro-survival and protective function of autophagy against the BOR-induce stress. On the contrary, when cells undergo to a stronger stress such as in the presence of HMCLs or by treatment with high dose of DEX we found that both proteasome inhibitors BOR and MG262 blocked autophagic cell death in osteocytes. To translate our in vitro evidence in a clinical perspective, thereafter we performed a histological evaluation on bone biopsies of a cohort of 37 newly diagnosis MM patients 31 of them with symptomatic MM and 6 with smoldering MM (SMM). The 55% of patients with MM have evidence of osteolytic lesions at the X-rays survey. Bone biopsies were obtained at the diagnosis and after an average time of 12 months of treatment or observation. Osteocyte viability was evaluated in a total of 500 lacunae per histological sections. A significant increase of the number of viable osteocytes was demonstrated in MM patients treated with BOR-based regimen as compared to those treated without BOR (% median increase: +6% vs. +1.30%; p=0.017). Patients treated with BOR alone showed the highest increase of osteocyte viability, as compared to those either treated without BOR (+11.6% vs. +1.3%, p=0.0019) or treated with BOR plus DEX (+11.6% vs. +4.4%, p=0.01). A reduction of both osteocyte apoptosis and autophagy was demonstrated by TUNEL assays and confocal microscopy. On the other hand, any significant difference was not observed in patients treated with Thalidomide (THAL) or Immunomodulatory drugs (IMiDs) than in those untreated with these drugs (p= 0.7). A multiple regression non-parametric analysis showed that BOR had a significant positive impact on osteocyte viability (p=0.042) whereas THAL/IMiDs as well as Zoledronic acid (ZOL) treatments have not (p=0.2). BOR also counterbalanced the negative effect of DEX treatment (p=0.035). Our data suggest that proteasome inhibitors blunted osteocyte cell death induced by MM cells and DEX through the modulation of the autophagy supporting their use to improve bone integrity in MM patients. Disclosures: Giuliani: Celgene Italy: Research Funding.

Download Full-text

Green tea polyphenols block the anticancer effects of bortezomib and other boronic acid–based proteasome inhibitors

Blood ◽

10.1182/blood-2008-07-171389 ◽

2009 ◽

Vol 113 (23) ◽

pp. 5927-5937 ◽

Cited By ~ 158

Author(s):

Encouse B. Golden ◽

Philip Y. Lam ◽

Adel Kardosh ◽

Kevin J. Gaffney ◽

Enrique Cadenas ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Tumor Cell ◽

Green Tea ◽

Boronic Acid ◽

Proteasome Inhibitors ◽

Green Tea Polyphenols ◽

Tumor Cell Death

Abstract The anticancer potency of green tea and its individual components is being intensely investigated, and some cancer patients already self-medicate with this “miracle herb” in hopes of augmenting the anticancer outcome of their chemotherapy. Bortezomib (BZM) is a proteasome inhibitor in clinical use for multiple myeloma. Here, we investigated whether the combination of these compounds would yield increased antitumor efficacy in multiple myeloma and glioblastoma cell lines in vitro and in vivo. Unexpectedly, we discovered that various green tea constituents, in particular (-)-epigallocatechin gallate (EGCG) and other polyphenols with 1,2-benzenediol moieties, effectively prevented tumor cell death induced by BZM in vitro and in vivo. This pronounced antagonistic function of EGCG was evident only with boronic acid–based proteasome inhibitors (BZM, MG-262, PS-IX), but not with several non–boronic acid proteasome inhibitors (MG-132, PS-I, nelfinavir). EGCG directly reacted with BZM and blocked its proteasome inhibitory function; as a consequence, BZM could not trigger endoplasmic reticulum stress or caspase-7 activation, and did not induce tumor cell death. Taken together, our results indicate that green tea polyphenols may have the potential to negate the therapeutic efficacy of BZM and suggest that consumption of green tea products may be contraindicated during cancer therapy with BZM.

Download Full-text

In Vitro and In Vivo Efficacy of a Novel Orally Bioavailable Beta-Catenin Inhibitor-BC2059- As Monotherapy or in Combination with Proteasome Inhibitors in Multiple Myeloma

Blood ◽

10.1182/blood.v126.23.1816.1816 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1816-1816

Author(s):

Ioanna Savvidou ◽

Tiffany T. Khong ◽

Stephen K. Horrigan ◽

Andrew Spencer

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Single Agent ◽

Proteasome Inhibitors ◽

Canonical Pathway ◽

Beta Catenin ◽

Dependent Manner ◽

Canonical Wnt

Abstract Background: The currently available treatment options are unlikely to be curative for the majority of Multiple Myeloma (MM) patients, emphasizing a continuing role for the introduction of investigational agents that overcome drug resistance. The canonical Wnt/β-catenin signalling pathway has been found to be dysregulated in MM, and its activation is associated with advanced stage MM, providing a rationale to evaluate the novel β-catenin inhibitor BC2059 in mono- and combination therapy with proteasome inhibitors in vitro and in vivo. Methods and Results: We evaluated the activation status of the canonical Wnt pathway in 12 genetically heterogeneous Human Myeloma Cell Lines (HMCL) by assessing the expression of β-catenin protein in the nuclear compartment (active form). This showed that nuclear β-catenin was present in all HMCL tested and absent in plasma cells derived from a healthy donor. Moreover, additional stimulation of the canonical pathway with rhWnt3a was shown to be pro-proliferative, in contrast, no proliferation was seen with activation of the non canonical pathway following treatment with rhWnt5a. BC2059 (50nM to 500nM) induced apoptosis of all 12 HMCL and was able to inhibit the proliferation of all HMCL tested in a dose and time dependent manner assessed by MTS assay and viable enumeration with trypan blue (IC50: 53nM to 247nM). Mimicking the bone marrow (BM) microenvironment by co-culturing HMCL with the immortalised human stromal cell line HS-5, BC2059 was able to overcome the protective effect of HS-5 (for example KMS18 at IC90=220nM had no stromal pro-survival effect). Similarly, BC2059 was able to abolish the pro-proliferative effect of rh-Wnt3a or conditioned media derived from MM patients' BM when used at doses >100nM or 50nM, respectively. BC2059 facilitated the degradation of β-catenin protein in the nuclear cellular compartment ( >50% decrease of nuclear β-catenin in KMS18 treated with 1.5xIC50 when compared with untreated cells), furthermore, using a reporter assay we showed that BC2059 inhibited TCF/LEF transcriptional activity in a dose-dependent manner and decreased the transcription of axin2, a down-stream target gene of β-catenin - 78% reduction in KMS18 cells treated with 1.5x IC50 when compared to untreated controls. BC2059-induced HMCL cell death was associated with activation of both the intrinsic and extrinsic caspase-dependent apoptotic pathways, as shown by the accumulation of the activated forms of caspases 8, 9 and 3 following BC2059 treatment. However, inhibition of the caspase-pathway by the addition of caspase inhibitors (pan-caspase inhibitor Z-VAD, and caspase-3 inhibitor Z-DEVD) could not abolish the pro-necrotic effect of BC2059 or BC2059 plus bortezomib, suggesting a possible role for autophagy-induced cell death. As β-catenin undergoes proteasome-mediated destruction and has been found to increase following bortezomib treatment, we evaluated the effect of combining BC2059 with Bortezomib. The combination was synergistic for 6/8 HMCL tested (e.g. for LP1 CI:0.64-0.55, where CI<1.1=synergism). We also evaluated the effect of the combination of BC2059 with next generation proteasome inhibitors (carfilzomib and marizomib) where it was shown to have synergistic and/or additive effects (e.g. for carfilzomib LP1 CI:0.33-0.99). Single agent BC2059 effectively killed primary MM tumour cells from relapsed/refractory MM patients (n=13) and the combination with bortezomib was synergistic (n=2) with no effect on healthy peripheral blood mononuclear cells (n=4). Finally, BC2059 (10mg/kg) prolonged survival of xenografted NSG mice compared to untreated controls with no major side effects in Wnt/β-catenin dependent tissues (GI track and haematopoiesis). Conclusion: We have demonstrated that BC2059 at nano-molar concentrations has a strong anti-MM effect both in vitro and in vivo and synergises with proteasome inhibitors. These data strongly support the clinical evaluation of BC2059 for the treatment of MM. Disclosures Horrigan: BetaCat Pharmaceuticals: Employment.

Download Full-text

Combination of proteasome inhibitors bortezomib and NPI-0052 trigger in vivo synergistic cytotoxicity in multiple myeloma

Blood ◽

10.1182/blood-2007-08-105601 ◽

2008 ◽

Vol 111 (3) ◽

pp. 1654-1664 ◽

Cited By ~ 138

Author(s):

Dharminder Chauhan ◽

Ajita Singh ◽

Mohan Brahmandam ◽

Klaus Podar ◽

Teru Hideshima ◽

...

Keyword(s):

Multiple Myeloma ◽

Proteasome Inhibitors ◽

Xenograft Model ◽

Er Stress Response ◽

Synergistic Cytotoxicity ◽

Proteolytic Activities ◽

Dose Combination ◽

Inhibition Of Tumor Growth

AbstractOur recent study demonstrated that a novel proteasome inhibitor NPI-0052 triggers apoptosis in multiple myeloma (MM) cells, and importantly, that is distinct from bortezomib (Velcade) in its chemical structure, effects on proteasome activities, and mechanisms of action. Here, we demonstrate that combining NPI-0052 and bortezomb induces synergistic anti-MM activity both in vitro using MM cell lines or patient CD138+ MM cells and in vivo in a human plasmacytoma xenograft mouse model. NPI-0052 plus bortezomib–induced synergistic apoptosis is associated with: (1) activation of caspase-8, caspase-9, caspase-3, and PARP; (2) induction of endoplasmic reticulum (ER) stress response and JNK; (3) inhibition of migration of MM cells and angiogenesis; (4) suppression of chymotrypsin-like (CT-L), caspase-like (C-L), and trypsin-like (T-L) proteolytic activities; and (5) blockade of NF-κB signaling. Studies in a xenograft model show that low dose combination of NPI-0052 and bortezomib is well tolerated and triggers synergistic inhibition of tumor growth and CT-L, C-L, and T-L proteasome activities in tumor cells. Immununostaining of MM tumors from NPI-0052 plus bortezomib–treated mice showed growth inhibition, apoptosis, and a decrease in associated angiogenesis. Taken together, our study provides the preclinical rationale for clinical protocols evaluating bortezomib together with NPI-0052 to improve patient outcome in MM.

Download Full-text

Improved Therapy of Multiple Myeloma by Combining Milatuzumab (Anti-CD74 Humanized mAb) and Bortezomib: In Vitro and In Vivo Results.

Blood ◽

10.1182/blood.v110.11.1176.1176 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1176-1176

Author(s):

Rhona Stein ◽

David M. Goldenberg

Keyword(s):

Multiple Myeloma ◽

Cell Lines ◽

Leukemic Cells ◽

Tumor Type ◽

Term Survival ◽

Significant Difference ◽

Highly Effective ◽

Ic50 Values

Abstract Background: The humanized anti-CD74 monoclonal antibody, milatuzumab (hLL1, or IMMU-115; Immunomedics, Inc, Morris Plains, NJ), is in clinical evaluation for therapy of multiple myeloma (MM) after preclinical evidence of activity in this tumor type (Stein et al, Blood2004;104:3705). Here we examine the ability of milatuzumab to increase the efficacy of drugs in MM cell lines. Methods: MTT cytotoxicity assays were performed on a panel of MM cell lines, including CAG, KMS11, KMS12-PE, and MC/CAR, to examine the effects of bortezomib, doxorubicin (dox), and dexamethasone (dex) alone and combined with milatuzumab or milatuzumab + crosslinking 2nd Ab (goat anti-human IgG, GAH). In vivo studies used a CAG-SCID mouse model of disseminated disease. Results: Without drugs, crosslinked milatuzumab, but not milatuzumab alone, yielded significant anti-proliferative effects on the four MM cell lines. In combination studies, crosslinked milatuzumab produced significant reductions in the IC50 values of the anti-MM drugs. For example, in CAG, milatuzumab+GAH decreased the IC50 values 58%, 78%, and 98% for bortezomib, dox, and dex, respectively (P=0.0034, 0.0073, and 0.078, respectively). In vivo, milatuzumab at 100 μg/injection, 2x weekly for 4 weeks, starting 1 day after injection of CAG cells, more than doubled the median survival time (MST) from 42 days in untreated CAG-bearing SCID mice to 103 days. Combination therapy with milatuzumab and bortezomib or dox was compared to milatuzumab alone, with treatments initiated 5 days after injection of CAG cells. Bortezomib alone (1.0 mg/kg) increased MST from 33 to 44 days (P=0.0021 vs. untreated). Treatment with milatuzumab alone (100 μg/mouse) increased the MST to 73 days (P<0.0001 vs. untreated). When bortezomib and milatuzumab treatments were combined, the MST increased to 93 days (P=0.0441 vs. milatuzumab and P=0.0065 vs. bortezomib). Thus, the combination of milatuzumab and bortezomib increased survival significantly compared to either single treatment. Given alone, dox yielded little or no effect on survival compared with untreated animals, and there was no significant difference between milatuzumab monotherapy and milatuzumab plus doxorubicin in this model. In contrast, a milatuzumabdox immunoconjugate was found to be a highly effective therapeutic agent, with all mice achieving long-term survival. The inhibition of the NF-κB survival pathway of B-leukemic cells by milatuzumab supports its complementary effects when combined with drugs having different mechanisms of action, such as bortezomib. Conclusions: The therapeutic efficacies of bortezomib, dox, and dex are enhanced in vitro in MM cell lines when given in combination with milatuzumab. In vivo, milatuzumab alone or especially in combination with bortezomib is highly effective in MM. (Supported in part by USPHS grant P01CA103985 from the NCI, and grants from the Thomas and Agnes Carvel Foundation and the Walter and Louise Sutcliffe Foundation.)

Download Full-text

In-Vitro and in-Vivo Synergistic Effect of Melphalan and Dual DNA Repair Inhibition in Multiple Myeloma

Blood ◽

10.1182/blood.v128.22.3301.3301 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3301-3301

Author(s):

Pritesh R. Patel ◽

Annie L. Oh ◽

Vitalyi Senyuk ◽

Dolores Mahmud ◽

Nadim Mahmud ◽

...

Keyword(s):

Multiple Myeloma ◽

Dna Repair ◽

Combination Index ◽

Fold Increase ◽

High Dose ◽

Myeloma Cells ◽

Synergistic Cytotoxicity ◽

Significant Difference

Abstract High dose melphalan is commonly used in patients with multiple myeloma (MM). Resistance to melphalan has been linked to the ability to repair DNA damage. To test whether DNA repair inhibitors overcome resistance to melphalan and and also have a direct anti-MM effect, we tested MM cell lines RPMI8226 and U266 in-vitro and in-vivo, using a NOD/SCID/ gamma null (NSG) xenograft model. RPMI8226 and U266 cells were initially treated in-vitro with the PARP inhibitor ABT-888. Using a proliferative assay, myeloma cells appeared sensitive to ABT-888 with low GI50 values (8.7μM for RPMI8226 cells, 49μM for U266 cells) and increased γH2AX foci, which persisted at 24 hours after treatment. This was confirmed in methycellulose colony assay where ABT-888 treatment reduced RPMI8226 colonies by 35% (p=0.002). Next we showed synergistic cytotoxicity between ABT-888 and melphalan. In both RPMI8226 and U266 cells strong synergy was displayed with a combination index (CI) less than 1 in proliferative assays (CI 0.5 and 0.3 at 50% proliferation respectively). Combination ABT-888 and melphalan treated cells underwent accelerated senescence compared to cells treated by melphalan alone (27% versus 51% βGal+ staining at 24 hours, p=0.02). This was confirmed by upregulation of senescence related genes p16 (1.6 fold increase) and p21 (1.5 fold increase). We did not find significant difference in apoptosis by Annexin V/ PI staining. Given that increased non-homologous end joining (NHEJ) activity has been shown to lead to resistance to melphalan, we tested whether an inhibitor of NHEJ could be synergistic with PARP inhibition and melphalan. Treatment with the DNA-PK inhibitor NU7026 at 10μM in addition to ABT-888 at 4μM resulted in 46% reduction in proliferation in RPMI8226 cells and 52% in U266 cells. When used in combination with melphalan chemotherapy, the dual DNA repair inhibitor therapy showed marked synergy in RPMI8226 cells with a combination index of 0.39. Finally we tested the ability of the combination of ABT-888 and melphalan to treat myeloma in-vivo. NSG mice were injected via tail vein with 5x106 RPMI8226 cells. Control (untreated) mice subsequently developed myeloma infiltrating the marrow, spleen and axial skeleton, with hind limb paralysis occurring at a median of 42 days. Treated mice received intraperitoneal injections of ABT-888 (3 times a week), or melphalan (weekly) or a combination of both agents starting on day 28 post-injection of MM cells for a total of 3 weeks. Using ABT-888, melphalan and a combination of both agents, median survival of mice was progressively prolonged (44 vs. 67 vs. 107 days, respectively) (p=0.02). Here we show that PARP and DNA-PK inhibition synergizes with melphalan in myeloma cells lines, providing a rationale for the addition of these agents to conditioning chemotherapy. In addition, we also show a direct anti-myeloma activity of these agents without the use of alkylator chemotherapy. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Modulating proteasome inhibitor tolerance in multiple myeloma: an alternative strategy to reverse inevitable resistance

British Journal of Cancer ◽

10.1038/s41416-020-01191-y ◽

2020 ◽

Cited By ~ 1

Author(s):

Maolin Ge ◽

Zhi Qiao ◽

Yan Kong ◽

Hongyu Liang ◽

Yan Sun ◽

...

Keyword(s):

Multiple Myeloma ◽

Histone Deacetylase Inhibitors ◽

Resistance Mechanism ◽

Proteasome Inhibitors ◽

Intermittent Therapy ◽

Bioinformatics Analyses ◽

Inhibitor Tolerance ◽

Epigenetic Regulators

Abstract Background Resistance to proteasome inhibitors (PIs) is a major obstacle to the successful treatment of multiple myeloma (MM). Many mechanisms have been proposed for PI resistance; however, our mechanistic understanding of how PI resistance is inevitably acquired and reversed remains incomplete. Methods MM patients after bortezomib relapse, MM cell lines and mouse models were used to generate matched resistant and reversed cells. RNA sequencing and bioinformatics analyses were employed to assess dysregulated epigenetic regulators. In vitro and in vivo procedures were used to characterise PI-tolerant cells and therapeutic efficacy. Results Upon PI treatment, MM cells enter a slow-cycling and reversible drug-tolerant state. This reversible phenotype is associated with epigenetic plasticity, which involves tolerance rather than persistence in patients with relapsed MM. Combination treatment with histone deacetylase inhibitors and high-dosage intermittent therapy, as opposed to sustained PI monotherapy, can be more effective in treating MM by preventing the emergence of PI-tolerant cells. The therapeutic basis is the reversal of dysregulated epigenetic regulators in MM patients. Conclusions We propose an alternative non-mutational PI resistance mechanism that explains why PI relapse is inevitable and why patients regain sensitivity after a ‘drug holiday’. Our study also suggests strategies for epigenetic elimination of drug-tolerant cells.

Download Full-text

Efficacy of Panobinostat (LBH589) in Multiple Myeloma Cell Lines and In Vivo Mouse Model: Tumor-Specific Cytotoxicity and Protection of Bone Integrity in Multiple Myeloma.

Blood ◽

10.1182/blood.v110.11.1510.1510 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1510-1510 ◽

Cited By ~ 2

Author(s):

Joseph D. Growney ◽

Peter Atadja ◽

Wenlin Shao ◽

Youzhen Wang ◽

Minying Pu ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Bone Density ◽

Mouse Model ◽

Cortical Bone ◽

Cell Lines ◽

Single Agent ◽

Synergistic Cytotoxicity

Abstract Panobinostat (LBH589) is a highly potent oral pan-deacetylase (DAC) inhibitor currently undergoing clinical development in hematologic and solid malignancies. Here we report the effects of panobinostat on multiple myeloma (MM) cells in vitro and in a murine xenograft model in vivo. Panobinostat exhibited potent cytotoxic activity (IC50 <10 nM) against 8 MM cell lines (KMS-12PE, KMS-18, LP-1, NCI H929, KMS-11, RPMI8226, OPM-2, and U266). Panobinostat has been shown to affect signals involved in MM cell-cycle arrest and cell death, and to induce apoptosis via mitochondrial perturbation. In addition, panobinostat has been shown to selectively induce cell death of plasma cells isolated from MM patients without toxicity to normal lymphocytes or granulocytes. To investigate the effect of panobinostat in vivo, a disseminated luciferized MM.1S xenograft mouse model was treated with vehicle or panobinostat 15 mg/kg by intraperitoneal (i.p.) administration qd×5 for 3 weeks. Panobinostat treatment reduced the burden of MM.1S tumor cells to 22% treated over control (T/C) relative to vehicle-treated animals. In addition, MM.1S tumor-bearing mice treated with panobinostat displayed reduced trabecular and cortical bone damage relative to vehicle-treated animals. The mean ± SEM trabecular bone density and cortical bone density (% Bone Volume/Total Volume) of panobinostat-treated animals was 14.5% ± 2.0 and 98.1% ± 0.4, respectively, compared with 2.2% ± 0.3 and 89.1% ± 1.5 in vehicle-treated animals. In combination with the proteosome inhibitor bortezomib (BZ), panobinostat displayed significant synergistic cytotoxicity without additional toxicity to normal bone marrow stromal cells in vitro. In the MM.1S-luciferase tumor mouse model, combined treatment with panobinostat at 10 mg/kg i.p. qd×5 for 4 weeks and BZ at 0.2 mg/kg intravenously 1qw for 4 weeks reduced tumor burden to 7% T/C relative to vehicle, panobinostat alone (31% T/C), or BZ alone (44% T/C). Disease progression, measured as median time to endpoint (TTE) was improved from 37 to 54 days (P<0.05) by panobinostat and to 46 days by BZ (P<0.05). The combination treatment further improved clinical outcome relative to both single-agent treatment groups (P<0.05), extending the TTE to 73 days. In contrast to BZ, the immunomodulatory drug thalidomide (TH) had no significant single-agent activity at 150 mg/kg p.o. qd for 4 weeks. However, combination activity (18% T/C) was observed when TH was combined with a sub-efficacious dose of panobinostat (5 mg/kg, 64% T/C). Combination of panobinostat and TH increased the TTE to 50 days, compared with 37.5, 43, and 39.5 days (P<0.05), respectively, for the vehicle, panobinostat, or TH as single agents. These data demonstrate that panobinostat exhibits significant anti-proliferative and anti-tumor activities on MM cells both in vitro and in vivo. Panobinostat, as a single agent or in combination with BZ or TH, is a promising therapy for MM, and these studies may provide the rationale for clinical evaluation of panobinostat and BZ combination in the treatment of MM.

Download Full-text

Galectin-1 Is Highly Expressed By Myeloma Cells and the Bone Marrow Microenvironment and Its Suppression Delineates a New Therapeutic in Vitro and in Vivo Strategy in Multiple Myeloma

Blood ◽

10.1182/blood.v124.21.3373.3373 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3373-3373

Author(s):

Paola Storti ◽

Gaetano Donofrio ◽

Valentina Marchica ◽

Daniela Guasco ◽

Katia Todoerti ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Cell Lines ◽

Expression Profiles ◽

Knock Down ◽

Hypoxic Conditions ◽

Bone Biopsies ◽

Hypoxic Treatment

Abstract Galectin-1 (Gal-1) is a lectin, involved in several processes related to cancer, including immunosuppression, angiogenesis, hypoxia, and metastases. However, the expression profiles of Gal-1 and its pathophysiological role in multiple myeloma (MM) cell growth, in the relationship between MM cells and the bone marrow (BM) microenvironment and in the MM-induced angiogenesis are unknown and were investigated in this study. Firstly we evaluatedGal-1 expression by CD138+ cells of a dataset of 133 MM patients at diagnosis (GSE16122) and 23 human myeloma cell lines (HMCLs) (GSE6205) or on a proprietary? dataset of primary mesenchymal stromal cells (MSCs) and osteoblasts (OBs) of 16 MM and 4 MGUS. CD138+ cells and HMCLs were positive for LGALS1 with no statistically significant differences. LGALS1 mRNA expression was positively correlated with 154 genes and negatively with 109 genes including ERG1 and SPARC. MSCs cells showed a higher expression of LGALS1 compared to the OBs and MM-OBs showed a higher expression of LGALS1 mRNA than that obtained from healthy subjects. Gene expression profiling (GEP) data were then validated by Real-Time PCR and western blot in freshly purified primary CD138+ and BM MSCs samples as well as in 6 HMCLs and in both human MSC (HS-5 and hMSC-Tert) and osteoblastic cell lines (HOBIT and HOB-01). Moreover, immunohistochemistry analyses on bone biopsies obtained from 12 MM, 9 smoldering MM, 9 MGUS and 3 plasma cell leukemia samples revealed an high level of Gal-1 protein expression by MM cells, OBs and vessels in all the patients tested. Secondly, we evaluated whether Gal-1 expression was regulated by hypoxia and by Hypoxia Inducible Factor-1a (HIF-1a) checking the effect of hypoxic treatment (1% of O2) and HIF-1α inhibition by shRNA lentivirus. We found that Gal-1 was upregulated in HMCLs upon hypoxic treatment and consistently the re-oxygenation process significantly restored the expression level of Gal-1. Interestingly the stable knock-down of HIF-1a significantly down-regulated Gal-1 expression in HMCLs both in normoxic and hypoxic conditions. Thereafter, we explored the effect of persistent Gal-1 inhibition in MM cells and BM microenvironment cells on cell proliferation, survival and the transcriptional and pro-angiogenic profiles. An anti-Gal-1 Lentivirus shRNA was used for Gal-1 stable knock-down in HMCLs (JJN3-anti-Gal-1 and OPM-2-anti-Gal-1) and MSC cell lines (HS-5 and HMSC-Tert) and the Scramble lentiviral vector (JJN3-Scramble and OPM-2-Scramble) was used as the empty control vector. The stable inhibition of Gal-1 did not affect the proliferation rate and viability of both HMCLs and MSC cell lines. On the other hand Gal-1 inhibition by shRNA lentivirus significantly modified the transcriptional profiles of HMCLs and HS-5, evaluated by U133 Plus2.0 Arrays (Affymetrix®) either in normoxic or hypoxic or re-oxygenation conditions. Among the genes significantly modulated by Gal-1 inhibition in HMCLs, we found that pro-angiogenic (eg. CCL2, MMP9) and adhesion molecules (eg. MCAM and STEAP1) were down-regulated by Gal-1 suppression in both normoxic and hypoxic conditions as well as some putative anti-tumoral genes, including EGR1, SPARC and TGFBI, and anti-angiogenic ones, including SEMA3A, were up-regulated by Gal-1 inhibition. In line with these observations, we found that Gal-1 suppression by shRNA significantly decreased the pro-angiogenic proprieties of HMCLs by an in vitro angiogenesis assay. Finally, we found that mice, injected subcutaneously with JJN3-anti-Gal-1 and OPM-2-anti-Gal-1, showed a reduction in the weight and volume of the tumor burden compared to mice inoculated with the JJN3-Scramble and OPM-2-Scramble. Moreover, a significant reduction in the number of CD34 positive vessels X field was observed. In an intratibial mouse model, JJN3-anti-Gal-1, JJN3-Scramble and JJN3 wild type were injected: in the anti-Gal-1 group tumors grew in reduced number and size compared to the Scramble group, moreover JJN3 anti-Gal-1 mice developed fewer and smaller lytic lesions on x-ray compared to the controls. Overall our data indicate that Gal-1 is highly expressed by MM cells and those of the BM microenvironment and that its expression is regulated by hypoxia. Gal-1 shows a role in MM-induced angiogenesis and its inhibition in MM cells significantly reduced tumor growth in vivo, suggesting that Gal-1 is a potential new therapeutic target in MM. Disclosures Giuliani: Celgene Italy: Research Funding.

Download Full-text

Pre-Clinical Activity of the Novel, First-in-Class p97 Inhibitor, CB-5083, in Multiple Myeloma

Blood ◽

10.1182/blood.v124.21.4701.4701 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4701-4701

Author(s):

Blake T. Aftab ◽

Daniel J Anderson ◽

Ronan Le Moigne ◽

Stevan Djakovic ◽

Eugen Dhimolea ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Cell Lines ◽

Proteasome Inhibitor ◽

Stromal Cell ◽

Hematological Malignancies ◽

Proteasome Inhibitors ◽

Protein Homeostasis ◽

Ubiquitinated Proteins

Abstract Hematological malignancies such as multiple myeloma (MM) have an increased reliance on the ubiquitin proteasome system (UPS) presumably as a consequence of their high protein synthetic and secretory burden. Chemical agents that target the proteasome, such as bortezomib and carfilzomib, have been successful in treating multiple myeloma; however patients treated with these drugs ultimately relapse. The AAA-ATPase p97/VCP (p97) facilitates ATP-dependent extraction and degradation of ubiquitinated proteins destined for proteasomal elimination. In addition to ubiquitin-dependent protein degradation, p97 is also closely involved in other aspects of protein homeostasis, including endoplasmic reticulum-associated degradation (ERAD) and autophagy. Pharmacologic inhibition of p97 provides a compelling therapeutic approach for hematological malignancies that rely on tight regulation of protein homeostasis as a component of their survival. CB-5083 is a novel small molecule inhibitor of p97 ATPase activity with nanomolar enzymatic and cellular potency. Treatment of cancer cells with CB-5083 causes a dramatic increase in poly-ubiquitinated proteins as well as an accumulation of substrates of the UPS and ERAD. CB-5083 causes a profound induction of the unfolded protein response (UPR) with consequent activation of the DR5 death receptor, caspase 8, caspase 3/7 and ultimately cell death. Induction of the UPR occurs to a greater magnitude with CB-5083 when compared to the proteasome inhibitor, bortezomib, suggesting the potential for increased efficacy in cancers with sensitivity to UPR-mediated cell death. In addition, activation of apoptosis and cell death occur more rapidly with CB-5083 than with bortezomib. Sequencing of cell lines made resistant to CB-5083 reveals missense mutations mapping to the D2 ATPase site in p97, supporting on-target association with cytotoxicity. In an expanded panel of MM cell lines there is no correlation between the cytotoxic sensitivity to CB-5083 and the cytotoxic sensitivity to proteasome inhibitors, suggesting differential mechanisms of cytotoxicity and potential activity of CB-5083 in proteasome inhibitor resistant settings. Compared to myeloma cell lines, CB-5083 has reduced cytotoxic potency in immortalized stromal cell lines and in patient-derived CD138-negative bone marrow mononuclear cells. Furthermore, unlike the reduced potency demonstrated by carfilzomib in the context of MM cell-bone marrow stromal cell (BMSC) interactions, the cyto-reductive potential of CB-5083 is unaffected in co-cultures of MM cells with patient-derived BMSCs or immortalized BMSCs from healthy donors. In vivo, CB-5083 is orally bioavailable, shows a pharmacodynamic effect in tumor tissue (as measured by poly-ubiquitin accumulation) and demonstrates robust anti-tumor activity across several MM models. CB-5083 treatment of mice bearing subcutaneous xenografts leads to tumor stasis and regression in RPMI8226 and AMO1 MM models, respectively. In advanced models of disseminated, ortho-metastatic disease, intermittent oral administration of CB-5083 demonstrates significant inhibition of myeloma burden and improves survival, with an overall efficacy profile that compares favorably to that of clinically approved proteasome inhibitors. Furthermore, in the Vk*Myc genetically engineered mouse model of MM, treatment with CB-5083 results in a significant reduction in M-spike by 55%. Combination treatment of mice bearing the RPMI8226 subcutaneous xenograft model with CB-5083, dexamethasone and lenalidomide results in tumor regression. Taken together, these data demonstrate that CB-5083 is a potent and selective inhibitor of the p97 ATPase with robust activity in vitro and in vivo in numerous MM models and strongly support clinical evaluation. Based on these observations, a phase 1 dose-escalation trial has recently been initiated and is currently underway in patients with relapsed/refractory multiple myeloma. Disclosures Anderson: Cleave Biosciences: Employment. Le Moigne:Cleave Biosciences: Employment. Djakovic:Cleave Biosciences: Employment. Rice:Cleave Biosciences: Employment. Wong:Cleave Biosciences: Employment. Kumar:Cleave Biosciences: Employment. Valle:Cleave Biosciences: Employment. Menon:Cleave Biosciences: Employment. Kiss von Soly:Cleave Biosciences: Employment. Wang:Cleave Biosciences: Employment. Yao:Cleave Biosciences: Employment. Soriano:Cleave Biosciences: Employment. Bergsagel:ONYX: Consultancy; Janssen: Consultancy; BMS: Consultancy; Novartis: Research Funding. Yakes:Cleave Biosciences: Employment. Zhou:Cleave Biosciences: Employment. Wustrow:Cleave Biosciences: Employment. Rolfe:Cleave Biosciences: Employment.

Download Full-text