Dual Antitumoral and Bone Antiresorptive Effect Of The Pan-Pim Kinase Inhibitor, LGH447, In Multiple Myeloma

Introduction Multiple myeloma (MM) is characterized by the accumulation of malignant plasma cells in the bone marrow (BM) and is closely associated with osteolytic lesions, in part due to an increase in the bone-resorptive activity and number of osteoclasts (OCs). The activation of survival pathways in myeloma cells could be the cause of treatment failure rendering the disease incurable. Pim kinases are a family of survival serine/threonine kinases composed of three members (Pim1, Pim2 and Pim3) that are overexpressed in MM cells and may have a role in MM pathogenesis. However, little is known about the role of Pim kinases in OCs and its involvement in myeloma bone disease. Here, we have evaluated the preclinical activity of a new pan-Pim kinase inhibitor, LGH447, on MM cells and OCs. Cell lines, primary samples, material and methods LGH447 was provided by Novartis Pharmaceuticals. The human MM cell lines MM1S, MM1R, RPMI-8226 (or RPMI-8226-luc), RPMI-LR5, MM144, NCI-H929, OPM-2, U266, U266-Dox4 and U266-LR7 were employed. PBMCs from healthy volunteers were used to generate OCs, whereas primary mesenchymal stromal cells (MSCs) were obtained from bone marrow aspirates of MM patients. Cell viability was studied using MTT colorimetric assay or bioluminescence. Apoptosis was measured by annexin-V staining. For cell cycle analysis, propidium iodide staining was used. OC formation was assessed by enumeration of multinucleated (≥3) TRAP-positive cells and OC resorption was assessed on calcium-coated slides. Immunoblotting, quantitative PCR and immunofluorescence were used to further investigate the mechanism of action of LGH447. Results All MM cell lines expressed the three isoforms of Pim kinases with higher levels of Pim2. The dose-response curves to LGH447 after a 48 hour treatment revealed two groups of MM cell lines with regard to sensitivity to this drug: high sensitive, with IC50 values ranging from 0.2 to 3.3 µM (MM1S, MM1R, RPMI-8226, MM144, U266 and NCI-H929); and low sensitive, with IC50 values >7 µM (OPM-2, RPMI-LR5, U266-Dox4 and U266-LR7). Our results indicated that LGH447 promoted apoptosis in myeloma cells as shown by the increase in annexin-V positive cells and by the cleavage of initiator (caspases 8 and 9) and effector caspases (caspases 3 and 7) and of PARP. LGH447 also blocked the cell cycle in MM cells as demonstrated by the increase in G0-G1 and the decrease in S-G2-M phases. Importantly, LGH447 was also able to overcome the growth advantage conferred to RPMI-8226-luc cells by co-culture with MSCs or OCs. Regarding the mechanisms involved in these effects, LGH447 inhibited the mTOR pathway, demonstrated by a decreased phosphorylation of the downstream mTOR effectors, 4EBP1 and S6 in residues Thr37/46 and Ser235/236, respectively. Interestingly, LGH447 also inhibited OC formation and resorption activity. LGH447 treatment of human pre-OCs diminished the expression of key molecules involved in OC differentiation (p-Erk1/2 and NFATc1) and function [CAII (carbonic anhidrase II), CLCN7 (chloride channel 7), ATP6V1A (vacuolar-H+-ATPase catalytic subunit A1) and MMP9 (matrix metalloproteinase 9)] and also disrupted the F-actin ring necessary for OC effective resorption. Conclusion Overall, our results demonstrate that both MM cells and OCs are targets of the pan-Pim kinase inhibitor, LGH447. Therefore, the inhibition of Pim kinases could potentially provide a dual benefit in myeloma patients as a consequence of cytotoxic effects exerted on MM cells and an anti-resorptive activity on bone. This work was supported by funding from the Fundación Española de Hematología y Hemoterapia (AG-G), Centro en Red de Medicina Regenerativa y Terapia Celular de Castilla y León, the RTICC-Hematology Group (RD12/0036/0058), Spanish FIS (PI12/02591) and the Junta de Castilla y León, Gerencia Regional de Salud (GRS 862/A/13). Disclosures: Off Label Use: LGH447 is a pan-Pim kinase inhibitor (Novartis Pharmaceuticals). It has been used for pre-clinical studies in multiple myeloma.

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Biochemical Basis for Interactions Between Thalidomide and Inhibitors of the Isoprenoid Biosynthetic Pathway in Multiple Myeloma Cells

Blood ◽

10.1182/blood.v112.11.2635.2635 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2635-2635

Author(s):

Sarah A. Holstein ◽

Huaxiang Tong ◽

Raymond J. Hohl

Keyword(s):

Multiple Myeloma ◽

Cell Lines ◽

Annexin V ◽

Differential Sensitivity ◽

Parp Cleavage ◽

Myeloma Cells ◽

Protein Isoprenylation ◽

Geranylgeranyl Transferase ◽

Synthase Inhibitor ◽

Rpmi 8226

Abstract Introduction: The isoprenoid biosynthetic pathway (IBP) is responsible for the production of key sterol and nonsterol species, including farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) which serve as substrates for protein isoprenylation reactions. Several agents known to target the IBP have been observed to have cytotoxic effects in multiple myeloma cells. Thalidomide (Thal) has emerged as an effective agent for treating multiple myeloma. While Thal has been noted to have a variety of direct and indirect effects on myeloma cells, the precise mechanism of action remains unknown. Aim: We examined interactions between inhibitors of the IBP and Thal in multiple myeloma cells. The mechanisms underlying the observed differential sensitivity to these agents were explored. Methods: Studies were performed in three human multiple myeloma cell lines (RPMI-8226, U266, H929). Cytotoxicity was assessed via MTT assays, while apoptosis induction was determined by Annexin V staining and evaluation of PARP cleavage. Western blot analysis was used to evaluate inhibition of protein isoprenylation. Intracellular FPP and GGPP levels were measured via enzymatic coupling to fluorescently-tagged peptides, HPLC fractionation and fluorescence detection. Pharmacologic manipulation of the IBP was achieved with the following agents: lovastatin (Lov) as an HMG-CoA reductase inhibitor, zoledronic acid (ZA) as a FPP synthase inhibitor, digeranyl bisphosphonate (DGBP) as a GGPP synthase inhibitor, FTI-277 as a farnesyl transferase inhibitor (FTI), and GGTI-286 as a geranylgeranyl transferase I inhibitor (GGTI). Results: Addition of Thal to Lov (at both 24 & 48h), zoledronic acid (at 48h), or DGBP (at 24 & 48h) in RPMI-8266 cells results in marked enhancement in cytotoxicity. Isobologram analysis could not be performed as Thal by itself does induce cytotoxicity in MTT assays. Although Lov induces cytotoxicity in a concentration- and time-dependent manner in the U266 and H929 cells, the addition of Thal did not result in increased cytotoxicity. Neither ZA nor DGBP induced cytotoxicity in the U266 cell line, while the H929 cell line showed effects only at 48 hours. Addition of Thal to FTI or GGTI did not result in enhanced cytotoxicity in tested cell lines. Annexin V experiments confirmed enhanced induction of apoptosis in RPMI-8226 cells incubated with the combination of Thal/Lov or Thal/DGBP. Add-back experiments revealed that the enhanced cytotoxicity/induction of apoptosis observed with the addition of Thal could be prevented with the addition of mevalonate or GGPP in Lov-treated cells or GGPP in DGBP-treated cells. PARP cleavage was demonstrated in RPMI-8226 and H929 cells treated with Lov or DGBP (with or without Thal) and in U266 cells treated with Lov. As expected, Lov resulted in the accumulation of unmodified forms of proteins normally farnesylated (Ras) and geranylgeranylated (Rap1a and Rab6) in these cells. Interestingly however, while DGBP led to accumulation of unmodified Rap1a and Rab6 in RPMI-8226 and H929 cells, no effect was seen in the U266 line. Examination of intracellular levels of FPP and GGPP revealed that the U266 line has markedly larger pools of FPP (8.5-fold) and GGPP (2.7-fold) compared to RPMI-8226 and that treatment with DGBP only partially depletes U266 cells of GGPP. Conclusions: These studies demonstrate an interaction between thalidomide and IBP inhibitors in multiple myeloma cells. These effects appear dependent on depletion of GGPP. Since treatment with a geranylgeranyl transferase-I inhibitor does not produce similar results, this suggests that substrates of geranylgeranyl transferase-II, such as the Rab proteins, may play critical roles in myeloma pathophysiology. The finding that intracellular levels of FPP and GGPP vary markedly amongst cell lines explains differential sensitivity of these cells to pharmacologic manipulation of the IBP and may also influence sensitivity to chemotherapeutic agents. Further studies will determine the extent to which isoprenoid pool sizes vary in primary samples and may ultimately allow for the identification of multiple myeloma patients who would benefit from the addition of an IBP inhibitor to their treatment plan. Figure Figure

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Reduced Response of IRE1α/Xbp-1 Signaling Pathway to Bortezomib Contributes to Drug Resistance in Multiple Myeloma Cells

Tumori Journal ◽

10.5301/tj.5000554 ◽

2016 ◽

Vol 103 (3) ◽

pp. 261-267 ◽

Cited By ~ 4

Author(s):

Xiaoxuan Xu ◽

Junru Liu ◽

Beihui Huang ◽

Meilan Chen ◽

Shiwen Yuan ◽

...

Keyword(s):

Multiple Myeloma ◽

Drug Resistance ◽

Signaling Pathway ◽

Cell Lines ◽

Resistance Mechanism ◽

Proteasome Inhibition ◽

Myeloma Cells ◽

Potential Marker ◽

Rpmi 8226 ◽

Basic Level

Purpose Proteasome inhibition with bortezomib eliminates multiple myeloma (MM) cells by partly disrupting unfolded protein response (UPR). However, the development of drug resistance limits its utility and resistance mechanism remains controversial. We aimed to investigate the role of IRE1α/Xbp-1 mediated branch of the UPR in bortezomib resistance. Methods The expression level of Xbp-1s was measured in 4 MM cell lines and correlated with sensitivity to bortezomib. LP1 and MY5 cells with different Xbp-1s level were treated with bortezomib; then pivotal UPR regulators were compared by immunoblotting. RPMI 8226 cells were transfected with plasmid pEX4-Xbp-1s and exposed to bortezomib; then apoptosis was determined by immunoblotting and flow cytometry. Bortezomib-resistant myeloma cells JJN3.BR were developed and the effect on UPR signaling pathway was determined. Results By analyzing 4 MM cell lines, we found little correlation between Xbp-1s basic level and bortezomib sensitivity. Bortezomib induced endoplasmic reticulum stress-initiated apoptosis via inhibiting IRE1α/Xbp-1 pathway regardless of Xbp-1s basic level. Exogenous Xbp-1s reduced cellular sensitivity to bortezomib, suggesting the change of Xbp-1s expression, not its basic level, is a potential marker of response to bortezomib in MM cells. Furthermore, sustained activation of IRE1α/Xbp-1 signaling pathway in JJN3.BR cells was identified. Conclusions Our data indicate that reduced response of IRE1α/Xbp-1 signaling pathway to bortezomib may contribute to drug resistance in myeloma cells.

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ABT-737, an Inhibitor of Bcl-2/Bcl-XL Proteins, Is Cytotoxic in Multiple Myeloma Cells.

Blood ◽

10.1182/blood.v106.11.1589.1589 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1589-1589

Author(s):

Michael Kline ◽

Terry Kimlinger ◽

Michael Timm ◽

Jessica Haug ◽

John A. Lust ◽

...

Keyword(s):

Multiple Myeloma ◽

Flow Cytometry ◽

Tumor Microenvironment ◽

Cell Lines ◽

Plasma Cells ◽

Annexin V ◽

Significant Activity ◽

Rpmi 8226 ◽

Dose Dependent

Abstract Background: Multiple myeloma (MM) is a plasma cell proliferative disorder that is incurable with the currently available therapeutics. New therapies based on better understanding of the disease biology are urgently needed. MM is characterized by accumulation of malignant plasma cells predominantly in the bone marrow. These plasma cells exhibit a relatively low proliferative rate as well as a low rate of apoptosis. Elevated expression of the anti-apoptotic Bcl-2 family members has been reported in MM cell lines as well as in primary patient samples and may be correlated with disease stage as well as resistance to therapy. ABT-737 (Abbott Laboratories, Abbott Park, IL) is a small-molecule inhibitor designed to specifically inhibit anti-apoptotic proteins of the Bcl-2 family and binds with high affinity to Bcl-XL, Bcl-2, and Bcl-w. ABT-737 exhibits toxicity in human tumor cell lines, malignant primary cells, and mouse tumor models. We have examined the in vitro activity of this compound in the context of MM to develop a rationale for future clinical evaluation. Methods: MM cell lines were cultured in RPMI 1640 containing 10% fetal bovine serum supplemented with L-Glutamine, penicillin, and streptomycin. The KAS-6/1 cell line was also supplemented with 1 ng/ml IL-6. Cytotoxicity of ABT-737 was measured using the MTT viability assay. Apoptosis was measured using flow cytometry upon cell staining with Annexin V-FITC and propidium iodide (PI). Flow cytometry was also used to measure BAX: Bcl-2 ratios after ABT-737 treatment and cell permeabilization with FIX & PERM (Caltag Laboratories, Burlingame, CA) Results: ABT-737 exhibited cytotoxicity in several MM cell lines including RPMI 8226, KAS-6/1, OPM-1, OPM-2, and U266 with an LC50 of 5-10μM. The drug also had significant activity against MM cell lines resistant to conventional agents such as melphalan (LR5) and dexamethasone (MM1.R) with similar LC50 (5-10 μM), as well as against doxorubicin resistant cells (Dox40), albeit at higher doses. Furthermore, ABT-737 retained activity in culture conditions reflective of the permissive tumor microenvironment, namely in the presence of VEGF, IL-6, or in co-culture with marrow-derived stromal cells. ABT-737 was also cytotoxic to freshly isolated primary patient MM cells. Time and dose dependent induction of apoptosis was confirmed using Annexin V/PI staining of the MM cell line RPMI 8226. Flow cytometry analysis of cells treated with ABT-737 demonstrated a time and dose dependent increase in pro-apoptotic BAX protein expression without significant change in the Bcl-XL or Bcl-2 expression. Ongoing studies are examining the parameters and mechanisms of ABT-737 cytotoxicity to MM cells in more detail. Conclusion: ABT-737 has significant activity against MM cell lines and patient derived primary MM cells in vitro. It is able to overcome resistance to conventional anti-myeloma agents suggesting a different mechanism of toxicity that may replace or supplement these therapies. Additionally, it appears to be able to overcome resistance offered by elements of the tumor microenvironment. The results of these studies will form the framework for future clinical evaluation of this agent in the clinical setting.

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CHIR258, a Novel Multi-Targeted Tyrosine Kinase Inhibitor, for the Treatment of t(4;14) Multiple Myeloma.

Blood ◽

10.1182/blood.v104.11.641.641 ◽

2004 ◽

Vol 104 (11) ◽

pp. 641-641 ◽

Cited By ~ 1

Author(s):

Suzanne Trudel ◽

Zhi Hua Li ◽

Ellen Wei ◽

Marion Wiesmann ◽

Katherine Rendahl ◽

...

Keyword(s):

Multiple Myeloma ◽

Mouse Model ◽

Tyrosine Kinase ◽

Cell Lines ◽

Small Molecule ◽

Kinase Inhibitor ◽

Wild Type ◽

Myeloma Cells

Abstract The t(4;14) translocation that occurs uniquely in a subset (15%) of multiple myeloma (MM) patients results in the ectopic expression of the receptor tyrosine kinase, Fibroblast Growth Factor Receptor3 (FGFR3). Wild-type FGFR3 induces proliferative signals in myeloma cells and appears to be weakly transforming in a hematopoeitic mouse model. The subsequent acquisition of FGFR3 activating mutations in some MM is associated with disease progression and is strongly transforming in several experimental models. The clinical impact of t(4;14) translocations has been demonstrated in several retrospective studies each reporting a marked reduction in overall survival. We have previously shown that inhibition of activated FGFR3 causes morphologic differentiation followed by apoptosis of FGFR3 expressing MM cell lines, validating activated FGFR3 as a therapeutic target in t(4;14) MM and encouraging the clinical development of FGFR3 inhibitors for the treatment of these poor-prognosis patients. CHIR258 is a small molecule kinase inhibitor that targets Class III–V RTKs and inhibits FGFR3 with an IC50 of 5 nM in an in vitro kinase assay. Potent anti-tumor and anti-angiogenic activity has been demonstrated in vitro and in vivo. We employed the IL-6 dependent cell line, B9 that has been engineered to express wild-type FGFR3 or active mutants of FGFR3 (Y373C, K650E, G384D and 807C), to screen CHIR258 for activity against FGFR3. CHIR258 differentially inhibited FGF-mediated growth of B9 expressing wild-type and mutant receptors found in MM, with an IC50 of 25 nM and 80 nM respectively as determined by MTT proliferation assay. Growth of these cells could be rescued by IL-6 demonstrating selectivity of CHIR258 for FGFR3. We then confirmed the activity of CHIR258 against FGFR3 expressing myeloma cells. CHIR258 inhibited the viability of FGFR3 expressing KMS11 (Y373C), KMS18 (G384D) and OPM-2 (K650E) cell lines with an IC50 of 100 nM, 250 nM and 80 nM, respectively. Importantly, inhibition with CHIR258 was still observed in the presence of IL-6, a potent growth factors for MM cells. U266 cells, which lack FGFR3 expression, displayed minimal growth inhibition demonstrating that at effective concentrations, CHIR258 exhibits minimal nonspecific cytotoxicity on MM cells. Further characterization of this finding demonstrated that inhibition of cell growth corresponded to G0/G1 cell cycle arrest and dose-dependent inhibition of downstream ERK phosphorylation. In responsive cell lines, CHIR258 induced apoptosis via caspase 3. In vitro combination analysis of CHIR258 and dexamethasone applied simultaneously to KMS11 cells indicated a synergistic interaction. In vivo studies demonstrated that CHIR258 induced tumor regression and inhibited growth of FGFR3 tumors in a plasmacytoma xenograft mouse model. Finally, CHIR258 produced cytotoxic responses in 4/5 primary myeloma samples derived from patients harboring a t(4;14) translocation. These data indicate that the small molecule inhibitor, CHIR258 potently inhibits FGFR3 and has activity against human MM cells setting the stage for a Phase I clinical trial of this compound in t(4;14) myeloma.

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ITF2357, a Novel Histone Deacetylase Inhibitor, Demonstrates Significant Apoptotic Activity Against Human Multiple Myeloma Cells.

Blood ◽

10.1182/blood.v110.11.4791.4791 ◽

2007 ◽

Vol 110 (11) ◽

pp. 4791-4791

Author(s):

Michael Kline ◽

Kathleen A. Donovan ◽

John A. Lust

Keyword(s):

Multiple Myeloma ◽

Cell Death ◽

Histone Deacetylase ◽

Cell Lines ◽

Hydroxamic Acid ◽

Stromal Cell ◽

Hdac Inhibitors ◽

Annexin V ◽

Myeloma Cells

Abstract We have evaluated the efficacy of a novel hydroxamic acid-derived histone deacetylase (HDAC) inhibitor, ITF2357, to promote cell death in multiple myeloma (MM) cells. HDAC inhibitors, which promote histone hyperacetylation and increase gene expression, have been evaluated as candidate agents for combating malignancies because they impact the expression of genes related to proliferation, differentiation, and survival. Exposure of MM cell lines to 1 micromolar ITF2357 led to dramatically increased levels of histone acetylation at 4 hours and 8 hours by Western analysis. Sub-micromolar concentrations of ITF2357 promoted time- and concentration-dependent cell death in MM cell lines. Using 500 nM ITF2357, a concentration potentially achievable in vivo, viability of KAS-6/1 IL-6 dependent myeloma cells was reduced to 28% of control at 24 hrs and 2% of control at 48 hours (Figure 1). In contrast, viability of normal PBMCs was 100% at 24 hours and 80% at 48 hours (Figure 2). U266 and 8226 myeloma cells were found to be sensitive to ITF-2357 in a similar fashion with U266 being least sensitive. Cell death proceeded via apoptosis as measured using Annexin V/propidium iodide staining. ITF 2357 was superior to suberoylanilide hydroxamic acid (SAHA) at inhibition of stromal cell IL-6 production. IL-1beta (10 pg/ml) was used to stimulate bone marrow stromal cell IL-6 production (105 ng/ml) after 48 hours. Concentration of ITF2357:Stromal Cell IL-6 production after 48 hours were as follows - 10 nM: 78 ng/ml; 100 nM: 79 ng/ml; 1000 nM; 32 ng/ml. SAHA at similar concentrations showed no significant decrease in stromal cell IL-6 production compared with the no drug control. In summary, ITF2357 induces significant myeloma cell apoptosis and can inhibit stromal cell IL-6 production. It represents an attractive therapeutic candidate for MM clinical trials. Figure Figure Figure Figure

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Comparative Analysis of in Vitro Chemosensitivity to Four Proteasome Inhibitors in Human Myeloma Cell Lines

Blood ◽

10.1182/blood.v124.21.3436.3436 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3436-3436

Author(s):

Amit Kumar Mitra ◽

Taylor S Harding ◽

Brian Van Ness

Keyword(s):

Multiple Myeloma ◽

Cell Viability ◽

Cell Lines ◽

Proteasome Inhibitors ◽

Genetic Characteristics ◽

Myeloma Cells ◽

In Vitro Chemosensitivity ◽

Wide Range ◽

Ic50 Values

Abstract Proteasome inhibitors (PI) are effective chemotherapeutic agents in the treatment of multiple myeloma (MM), used alone or in combination with other anti-cancer agents, such as alkylating agents, topoisomerase inhibitors, corticosteroids, histone deacetylase inhibitors (HDACis) and immunomodulatory drugs (IMiDs). Bortezomib (Velcade/Bz) was the first PI to be approved by US-FDA for the treatment of relapsed and refractory MM. Other second generation PIs include carfilzomib (Kyprolis/Cz), ixazomib/Iz and oprozomib (Opz). Wide inter-individual variation in response to treatment with PIs is a major limitation in achieving consistent therapeutic effect in MM. Yet few studies have compared the efficacy of all four PIs in a range of myeloma subtypes. In our current study, we performed comprehensive in vitro chemosensitivity profiling of response to four (4) PIs (Bz, Cz, Ix and Opz) in a panel of forty-five (45) human myeloma cells lines (HMCLs) generated through the immortalization of primary multiple myeloma cells (MMCs) and representing the biological and genetic heterogeneity of MM with regards to chromosomal abnormalities, oncogene mutations (e.g. Ras), tumor suppressor variations (e.g. p53), cell surface phenotypes, or growth factor response. Cells were treated with increasing concentrations of Bz, Cz, Ix and Opz as single agents and cell viability assays were performed using CellTiter-Glo luminescent cell viability assay to generate survival curves and determine the half maximal inhibitory concentration (IC50) values by calculating the nonlinear regression using sigmoidal dose-response equation (variable slope). Our results in comparing the cellular responses to PI treatment among HMCLs showed wide range of variability in IC50 values identifying some lines which were highly sensitive and some lines relatively refractory to PI treatment. Pearson product-moment correlation (PPMC) test demonstrated statistically significant (adjusted p values < 0.001) positive correlation between IC50 values of the following drug pairs: Bz vs Opz (r = 0.82); and Ix vs Opz (r = 0.88); Bz vs Ix (r = 0.65); Cz vs Opz (r = 0.69) and Cz vs Ix (r = 0.63). Subgroup analysis revealed significant correlation between carfizomib IC50 and chromosome number (p < 0.05). Furthermore, it was interesting to note that although all 4 drugs belong to the same drug class (PI), not all cell lines responded the same across all PI treatments. This demonstrates tumor heterogeneity even in response to inhibitors of the same class, and further demonstrates tumors refractory to one PI may still respond to another. We are currently examining genetic characteristics that are associated with response among the four PIs, and analysis of these characteristics will be presented. Disclosures No relevant conflicts of interest to declare.

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PIM Kinase Inhibition Decreases the Proangiogenic Properties of Multiple Myeloma Cells and Affects the Metabolic State of the Vascular Endothelium

Blood ◽

10.1182/blood-2020-134979 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 16-17

Author(s):

Filip Garbicz ◽

Anna Szumera-Ciećkiewicz ◽

Joanna Barankiewicz ◽

Dorota Komar ◽

Michał Pawlak ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Endothelial Cells ◽

Cell Death ◽

Tumor Cell ◽

Cell Lines ◽

Fold Increase ◽

Pim Kinases ◽

Rpmi 8226

The development and progression of multiple myeloma (MM) depend on the formation and perpetual evolution of an immunosuppressive and hypervascular bone marrow microenvironment. MM undergoes an angiogenic switch during its early progression stages and initiates the secretion of proangiogenic proteins, such as VEGFA and Galectin-1. Following their engagement with the VEGF receptor 2 on the surface of the endothelium, quiescent endothelial cells (ECs) rapidly switch to an activated state, thus gaining the ability to create sprouts, migrate and proliferate. However, chronic angiogenic stimulation results in the formation of a dense and leaky network of pathological vessels, which in the case of MM also serves as a major source of prosurvival paracrine signals. Since PIM kinases are known modulators of cytokine signaling, owing to their ability to activate NFκB, JAK/STAT and mTOR pathways, we analyzed the expression pattern of PIM1, PIM2 and PIM3 in multiple myeloma bone marrow samples using immunohistochemistry. We found that both MM cells as well as myeloma-associated ECs exhibit a significantly higher PIM3 expression than their normal bone marrow counterparts. Since the role of PIM kinases in the vascular compartment of the tumor microenvironment is currently unknown, we decided to explore the proangiogenic functions of PIM kinases using in vitro MM and EC model cell lines. 3 MM cell lines (RPMI 8226, MM1.s, U266), immortalized bone marrow ECs (HBMEC-60) and human umbilical vein ECs (HUVECs) were used for the experiments. Primary MM cells were obtained from MACS-separated bone marrow aspirates. Chemical blockade of PIM kinase activity was achieved using the pan-PIM inhibitor SEL24/MEN1703. The compound decreased the viability of MM cell lines with IC50 in the submicromolar range, induced G2 cell cycle arrest and apoptosis. Moreover, SEL24/MEN1703 induced apoptosis in primary MM cells, even when cocultured with the CD138- bone marrow fraction. PIM inhibitor treatment inhibited the phosphorylation of mTOR substrates S6 and 4EBP1, STAT3/5, as well as RelA/p65. Consequently, we observed markedly decreased VEGFA and Gal-1 levels in SEL24/MEN1703-treated MM cells. When cultured together, separated by a permeable transwell membrane, both RPMI 8226 cells, as well as ECs, exhibited a 2-fold increase in proliferation rate. This effect was completely blocked by a 2-day treatment with a PIM inhibitor. Exposure of ECs to recombinant VEGFA (10ng/ul) or MM supernatant resulted in an increase in VEGFR2 Y1175 phosphorylation level and induction of PIM3 expression. Increased MYC activity is a hallmark of VEGF-dependent endothelial activation and is necessary to support the creation of new vessels. Since the PIM3 promoter region contains putative MYC-binding sites (E-boxes), we checked if PIM3 induction depends on MYC in ECs. MYC silencing using siRNA resulted in an 88% lower PIM3 expression than the non-targeting siRNA. One of MYC's main tasks during angiogenesis is the stimulation of cellular ATP synthesis to meet the energy demands created by the dynamic remodeling of the actin cytoskeleton. Surprisingly, PIM inhibition decreased the total ATP content in ECs by 25%, thus disrupting the energetic homeostasis, as evidenced by a 9.6-fold increase in phosphorylated AMPK T172 levels. Furthermore, SEL24/MEN1703-treated ECs were depleted of higher-order actin structures necessary for efficient angiogenesis, such as actin stress fibers, membrane ruffles and lamellipodia. In consequence, PIM kinase inhibition decreased proliferation, migration and formation of new vessel-like structures in Matrigel by ECs. Collectively, our data demonstrate that PIM inhibition induces MM cell death and abolishes important tumor cell-ECs interactions. In addition, we show that PIM3 is overexpressed in MM tumor endothelial cells and PIM inhibition disrupts the activation state in in vitro cultured ECs. Hence, targeting PIM kinases may represent an efficient approach to induce tumor cell death and to block angiogenesis in MM. RNA-sequencing studies on the downstream effectors of PIM3 are currently ongoing in order to unravel the molecular mechanism behind the observed effects. Figure Disclosures Brzózka: Ryvu Therapeutics: Current Employment. Rzymski:Ryvu Therapeutics: Current Employment. Tomirotti:Menarini Ricerche: Current Employment. Lech-Marańda:Roche, Novartis, Takeda, Janssen-Cilag, Amgen, Gilead, AbbVie, Sanofi: Consultancy; Roche, Amgen, Gilead: Speakers Bureau. Juszczynski:Ryvu Therapeutics: Other: member of advisory board.

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A Role for Syntenin-1 in Multiple Myeloma Cell Survival

Blood ◽

10.1182/blood-2018-99-113594 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1008-1008

Author(s):

Tyler Moser-Katz ◽

Catherine M. Gavile ◽

Benjamin G Barwick ◽

Sagar Lonial ◽

Lawrence H. Boise

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Cell Death ◽

Cell Survival ◽

Cell Lines ◽

Plasma Cells ◽

Surface Expression ◽

Myeloma Cell ◽

Myeloma Cells ◽

Rpmi 8226

Abstract Multiple myeloma is the second most common hematological malignancy in the U.S. with an estimated 30,700 new diagnoses in 2018. It is a clonal disease of plasma cells that, despite recent therapeutic advances, remains incurable. Myeloma cells retain numerous characteristics of normal plasma cells including reliance on survival signals in the bone marrow for long term viability. However, malignant transformation of plasma cells imparts the ability to proliferate, causing harmful bone lesions in patients, and in advanced stages independence of the bone-marrow microenvironment. Therefore, we are investigating the molecular mechanisms of myeloma cell survival that allow them to become extramedullary. We identified syntenin-1 (SDCBP) as a protein involved in myeloma cell survival and a potential therapeutic target. Syntenin-1 is an adapter protein that has been shown to regulate surface expression of several transmembrane proteins by binding with membrane phospholipids and mediating vesicular trafficking of proteins throughout the cell. Syntenin-1 regulates the surface expression of CD138, a plasma/myeloma cell marker. Syntenin-1 has been shown to regulate apoptosis in numerous cancer cell lines including breast cancer, glioma, and pancreatic cancer but its role in multiple myeloma survival has not been studied. To determine if syntenin-1 expression has an effect on myeloma cell survival, we utilized the CoMMpass dataset (IA12), a longitudinal study of myeloma patients that includes transcriptomic analysis throughout treatment. We found that patients with the highest expression of syntenin-1 mRNA (top quartile) had significantly worse overall survival, progression-free survival, and a shorter response duration than those in the bottom quartile of expression. To determine if syntenin-1 has a role in myeloma cell survival, we used short hairpin RNA to knock down syntenin-1 (shsyn) in RPMI 8226 and MM1.s myeloma cell lines. We then determined the amount of cell death using Annexin-V staining flow cytometry four days following lentiviral infection. We found increased cell death in syntenin-1-silenced cells compared to our empty vector control in both RPMI 8226 (control=42.17%, shsyn=71.53%, p=0.04) and MM1.s cell lines (control=8.57%, shsyn=29.9%, p=0.04) suggesting that syntenin-1 is important for myeloma cell survival. Syntenin-1 contains two PDZ domains that allow it to bind to receptor proteins via their corresponding PDZ-binding motifs. We therefore wanted to look at correlation of syntenin-1 expression with CD138 and CD86, two PDZ-binding domain containing proteins expressed on the surface of myeloma cells. Using the CoMMpass dataset, we found patients with high expression of syntenin-1 had a median expression of CD86 that was twice as high as the total population (P<0.0001) while syntenin-1-low patients expressed CD86 at levels that were half as much as the population (P<0.0001). In contrast, there was no clear relationship between syntenin-1 and CD138 mRNA expression. Indeed if one takes into account all patients, there is a positive correlation between CD86 and syntenin-1 expression (r=0.228, P<0.0001) while there is a negative correlation between CD138 and syntenin-1 (r=-0.1923, P<0.0001). The correlation with CD86 but not CD138 suggests a previously undescribed role for syntenin-1 in myeloma cells. Our lab has previously shown that expression of CD86 is necessary for myeloma cell survival, and signals via its cytoplasmic domain to confer drug resistance. Silencing syntenin-1 results in a decrease in CD86 surface expression. However, there is no change in CD86 transcript or total cellular CD86 protein levels in our shsyn treated cells. Moreover, knockdown of CD86 resulted in increased protein expression and transcript levels of syntenin-1. Taken together, these data suggest that syntenin-1 may regulate CD86 expression on the cell surface. Our data supports a novel role for syntenin-1 in myeloma cell viability and as a potential regulator of CD86 surface expression. The role of syntenin-1 has not previously been explored in multiple myeloma and determining its molecular function is warranted as it may be an attractive target for therapeutic treatment of the disease. Disclosures Lonial: Amgen: Research Funding. Boise:AstraZeneca: Honoraria; Abbvie: Consultancy.

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Inhibition of Aurora-Kinases for Tailored Risk-Adapted Treatment of Multiple Myeloma

Blood ◽

10.1182/blood.v112.11.248.248 ◽

2008 ◽

Vol 112 (11) ◽

pp. 248-248

Author(s):

Dirk Hose ◽

Thierry Rème ◽

Tobias Meißner ◽

Jérôme Moreaux ◽

Anja Seckinger ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Lines ◽

Chromosomal Aberrations ◽

Genetic Instability ◽

Kinase Inhibitor ◽

Aurora Kinase ◽

Myeloma Cell ◽

High Dose ◽

Aurora A ◽

Myeloma Cells

Abstract BACKGROUND. At the time of diagnosis, myeloma cells are characterized by a low proliferation rate that increases in relapse. Presence of proliferation correlates with adverse prognosis. At the same time, myeloma cells harbor a high median number of chromosomal aberrations, often associated with genetic instability. Cellular proliferation and genetic instability in turn have been associated with Aurora-kinase expression in several cancer entities, including multiple myeloma. PATIENTS AND METHODS. Expression of Aurora-A, -B and -C was assessed using Affymetrix DNA-microarrays in 784 samples including two independent sets of 233 and 345 CD138-purified myeloma cells from previously untreated patients. Chromosomal aberrations were assessed by comprehensive iFISH using a set of probes for the chromosomal regions 1q21, 6q21, 8p21, 9q34, 11q23, 11q13, 13q14.3, 14q32, 15q22, 17p13, 19q13, 22q11, as well as the translocations t(4;14)(p16.3;q32.3) and t(11;14) (q13;q32.3). Proliferation of primary myeloma cells (n=67) was determined by propidium iodine staining. The effect of the clinical Aurora-kinase inhibitor VX680 on proliferation of 20 human myeloma cell lines and survival of 5 primary myeloma cell-samples was tested. RESULTS. We found Aurora-A and -B to be expressed at varying frequencies in primary myeloma cells of different patient-cohorts, including 23% for Aurora A in our first cohort of patients treated with high dose therapy (see figure shown below). Aurora-C expression was found in testis-samples only. Myeloma cell-samples with detectable Aurora-A expression show a significantly higher proliferation rate, whereas the number of chromosomal aberrations (aneuploidy) is not higher compared to myeloma-cells with absent Aurora-A expression. The same holds true for subclonal aberrations (i.e. genetic instability). The Aurora-kinase inhibitor VX680 induces apoptosis in all myeloma cell lines and primary myeloma cell-samples tested. Presence of Aurora-A expression delineates significantly inferior event-free and overall survival in two independent cohorts of patients undergoing high-dose chemotherapy and autologous stem cell transplantation. This observation is independent of conventional prognostic factors, i.e. serum-ß2-microglobulin or ISS-stage. CONCLUSION. Aurora-kinase inhibitors (including VX680 tested here) are very active on myeloma cell lines as well as primary myeloma cells and represent a promising weapon in the therapeutic arsenal against multiple myeloma. Gene expression profiling allows the assessment of Aurora-kinase expression and thus in turn a tailoring of treatment to patients expressing Aurora-A associated with adverse prognosis. Figure Figure

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Type I MAGE Proteins: Novel Markers of Proliferation in Multiple Myeloma Progenitor Cells.

Blood ◽

10.1182/blood.v106.11.5115.5115 ◽

2005 ◽

Vol 106 (11) ◽

pp. 5115-5115

Author(s):

Hearn J. Cho ◽

Otavia Caballero ◽

Achim A. Jungbluth ◽

Maurizio DiLiberto ◽

Ruben Niesvizky ◽

...

Keyword(s):

Multiple Myeloma ◽

Molecular Markers ◽

Cell Line ◽

Progenitor Cells ◽

Cell Lines ◽

Primary Antibody ◽

Type I ◽

Color Analysis ◽

Myeloma Cells ◽

Rpmi 8226

Abstract CT7 (MAGE-C1) and MAGE-A3, two members of the type I MAGE family of Cancer-Testis antigens, are commonly expressed at both the mRNA and protein levels in primary tumor specimens from multiple myeloma patients. In previous analyses, tumors with higher percentages of type I MAGE-expressing cells had a positive correlation with abnormally elevated plasma cell proliferation. These data support the hypothesis that type I MAGE proteins are molecular markers of proliferating myeloma progenitor cells (the so-called “myeloma stem cell”) and may play a role in the pathobiology of this disease. To test this hypothesis, we examined the expression of type I MAGE in proliferating myeloma cells by flow cytometry. Human multiple myeloma cell lines U266, RPMI-8226, and KMS-11 were co-cultured for 12 or 24 hours with the nucleoside analog bromodeoxyuridine (BrdU), then fixed, permeabilized, and stained with CT7-33, a monoclonal antibody (mAb) to CT7, or M3H67 (to MAGE-A3), followed by a phycoerythrin (PE)-conjugated secondary mAb. The cells were then treated with DNAse and stained with a fluoroisothiocyanate (FITC)-conjugated mAb against BrdU. Proliferating cells that incorporated BrdU into their DNA exhibited high FITC fluorescence. For mAb M3H67, dual color analysis of this population showed that greater than 99% demonstrated a significant shift in PE fluorescence in all three of these cell lines as measured by Mean Fluorescence Index (MFI= geometric mean fluorescence [specific primary antibody]/mean fluorescence [no primary antibody], table 1). For CT7-33 mAb, greater than 85% demonstrated a shift in two of three lines (U266 and KMS-11), but not in RPMI-8226. For all three of these cell lines, dual color analysis of the BrdU-low population demonstrated less than 65% staining with either type I MAGE mAb. Interestingly, RT-PCR with CT7-specific primers of total RNA from RPMI-8226 revealed a product of lower molecular weight than expected, suggesting that a gene deletion occurred in this cell line possibly resulting in a stop codon, decreased translation, or decreased protein stability. This PCR product is being sequenced to determine the nature of the deletion. These results demonstrate that type I MAGE proteins are expressed in proliferating myeloma cells and are molecular markers of this population. These data suggest that novel therapeutics such as vaccines that target type I MAGE may preferentially eliminate the cycling myeloma cells, resulting in long-term cures. Table 1. Type I MAGE expression in proliferating (BrdU+) myeloma cells Cell line MFI CT7-33 MFI M3H67 U266 65.8 62.5 KMS-11 9.9 48.4 RPMI-8226 3.1 12.3

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