Interfering with Arginine Metabolism As a New Treatment Strategy for Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3005-3005
Author(s):  
Bjoern Jacobi ◽  
Lea Stroeher ◽  
Nadine Leuchtner ◽  
Hakim Echchannaoui ◽  
Alexander Desuki ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Lines ◽  
Caspase 3 ◽  
Xenograft Model ◽  
Myeloma Cell ◽  
Intracellular Protein ◽  
Myeloma Cells ◽  
Induction Of Apoptosis

Abstract Introduction Starvation of tumor cells from the amino acid arginine has recently gained particular interest because of the downregulation of the rate-limiting enzyme argininosuccinate synthethase 1 (ASS1) in various cancer entities. ASS1-deficient cells cannot resynthesize arginine from citrulline and are therefore considered arginine auxotrophic. The arginine depleting enzyme arginine deiminase (ADI-PEG20, Polaris Pharmaceuticals) is currently tested in phase I-III clinical trials for different arginine auxotrophic cancers. The natural arginine analogue canavanine can compete with arginine for arginyl-tRNA-binding sites and consequently be incorporated into nascent proteins instead of arginine. Canavanine could therefore potentially further disturb intracellular protein homeostasis, especially under arginine deprivation. The sensitivity of myeloma cells towards arginine depletion strategies has not been analyzed so far. Methods Human myeloma cell lines and CD138-sorted primary human myeloma cells from patient bone marrow were screened for ASS1 expression by western blotting (WB). The cells were cultured in arginine free medium and assessed for proliferation and metabolic activity (CFSE/MTT assays), apoptosis (caspase-3 cleavage) and cell death (annexinV/propidium iodide). Canavanine was supplied in both arginine-sufficient and -deficient conditions. The level of intracellular protein stress was determined by WB and/or flow cytometry analysis for ubiquitinated proteins, phosphorylated eukaryotic initiation factor 2α (peIF2α) and the spliced isoform of the X-Box binding protein 1 (Xbp1s). Repetitive ADI-PEG20 ± canavanine application i.p. were tested in vivo in an U266 myeloma xenograft model in NOD/SCID/IL2Rcg-/- (NSG) mice. Arginine and canavanine levels in plasma were determined by HPLC. Tumor growth was measured, mice were assessed for survival, weight and side effects. Tumor tissues were analyzed for caspase-3 cleavage and Ki67 expression by immunohistochemistry. Results 5 of 6 myeloma cell lines were negative for ASS1. Also, ASS1 was either not or only weakly expressed in the majority of primary CD138+ myeloma patient samples. Arginine starvation induced an arrest of cell proliferation and/or metabolic activity of primary myeloma cells and myeloma cell lines after 18-24 h. Addition of citrulline could only rescue ASS1 positive myeloma cells due to the intracellular resynthesis of arginine. Arginine starvation alone led to delayed induction of apoptosis (e.g. 35% cell death of NCI-H929 cells after 72 h of treatment). Addition of 100 mM canavanine strongly increased cell death specifically in the context of arginine deficiency (e.g. cell death in NCI-H929 cells: 87% after 24 h, 100 % after 48h) while it was non-toxic and had no effect on cell viability under physiological arginine conditions. Co-application of canavanine induced ubiquitination of cellular proteins and led to the prolongation of a fatal unfolded protein response (UPR) as measured by markedly elevated Xbp1s levels. Prolonged UPR ultimately led to the induction of apoptosis as reflected by annexin V binding and caspase-3 cleavage. In an U266 myeloma NSG xenograft model, systemic arginine depletion by ADI-PEG20 suppressed tumor growth in vivo and significantly prolonged median survival of mice when compared with the control group (22±3 vs. 15±3 days). Canavanine treatment alone had no influence on viability (13±0 days). However, the combination of ADI-PEG20 and canavanine demonstrated the longest median survival (27±7 days). Histological examination of explanted tumors showed the highest rates of caspase-3 cleavage in the ADI-PEG20/canavanine group. Conclusion Myeloma cells are mostly arginine auxotrophic and can be selectively targeted by arginine starvation. Combination of arginine depletion with the arginine analogue canavanine leads to a highly efficient and specific tumor cell eradication and should be further optimized in multiple myeloma preclinical models. Disclosures Bomalaski: Polaris Pharmaceuticals Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Induction of Apoptosis and Anti-Tumor Effects of a Novel Pan Inhibitor of Bcl-2 and Mcl-1 Apogossypolone (ApoG2) in Multiple Myeloma Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2601-2601
Author(s):  
Jie Lin ◽  
Yongji Wu ◽  
Shujie Wang ◽  
Dajun Yang ◽  
Yongqiang Zhao
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Growth Inhibition ◽  
Caspase 3 ◽  
Xenograft Model ◽  
Caspase 9 ◽  
Dna Ladder ◽  
Myeloma Cells ◽  
Induction Of Apoptosis

Abstract Multiple myeloma remains an incurable malignancy and overall survival has not been improved despite responses to conventional and high-dose chemotherapy. Over-expression of both Bcl-2 and Mcl-1 is frequent in multiple myeloma which renders myeloma cells resistant to apoptosis by chemotherapy, and overexpression is associated with relapse and poorer survival. Inhibition of the anti-apoptotic function of Bcl-2 family member proteins such as Bcl-2 and Mcl-1 represents an attractive new strategy for developing anticancer drugs. Apogossypolone (ApoG2) is a novel derivative of the naturally occurring polyphenolic compound gossypol which has aldehyde moieties removed and further modification to make it pharmaceutically more stable. More particularly, ApoG2 is a potent inhibitor of Mcl-1 and Bcl-2, with Ki value of 25 nM for Mcl-1, 35 nM for Bcl-2, respectively. In this study, trypan blue dye exclusion, Hoechst 33258 staining, DNA ladder formation and annexin-V-PI flow cytometric analysis were used to determine the cellular activities of ApoG2 on cell growth inhibition, cell viability, cell cycle and apoptosis. Cleavage of caspase-3 and caspase-9 was analyzed by colorimetirc assay. Xenograft model of Wus1 cells (from Peking Union Medical College Hospital) in nude mice were used to determine the antitumor activity of compounds. We found that ApoG2 resulted in a dose and time-dependent inhibition of multiple myeloma cell proliferation, with IC50 value to both U266 and Wus1 cells at 0.1 to 0.2 uM at 48 hours after treatment. ApoG2 effectively induced apoptosis of multiple myeloma cells as evidenced by typical morphological changes, transmission electron microscopy, DNA ladder formation and increase in the percentage of cells in subdiploid peak. Colorimetric assays further showed activation of both caspase-3 and caspase-9. In a parallel direct comparison study, ApoG2 was more potent than the parental compound gossypol in both growth inhibition and induction of apoptosis. Of interest, cell cycle analysis of both U266 and Wus1 cells treated with ApoG2 produced a slightly G2 arrest, increasing from 9.7% to 19.6% in U266 cells, and from 9.8% to 31.7% in Wus1 cells, respectively. This was different from gossypol which induced mainly G1 arrest. Preliminary in vivo antitumor activity of ApoG2 was examined in xenograft model of Wus1 cells in nude mice, and growth inhibition (T/C) of 32.7% and 33.4% was obtained at 60 mg/kg, and 40 mg/kg, respectively. In addition, there was no body weight loss for both treated groups in comparison with the vehicle treated mice. Our results demonstrated that a potent pan inhibitor of Bcl-2 and Mcl-1 ApoG2 had significant effect of antiproliferation and induction of apoptosis on multiple myeloma cells in vitro and in vivo. ApoG2 may represent a promising new anticancer agent with a novel molecular mechanism and warrant further investigation as a single agent or in combination for human multiple myeloma with Bcl-2/Mcl-1 overexpression.

Targeting NF-κB and Induction of Apoptosis by Dehydroxymethylepoxyquinomicin (DHMEQ) in Multiple Myeloma Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3393-3393
Author(s):  
Yoshitaka Miyakawa ◽  
Kanoko Kohmura ◽  
Kaori Saito ◽  
Hiroshi Yoshida ◽  
Asako Ikejima ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Lines ◽  
Caspase 3 ◽  
Regulatory Protein ◽  
Active Form ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract We previously designed and synthesized a new NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ) (J Biol Chem, 2002). DHMEQ is a derivative of the weak antibiotics epoxyquinomicin C, which was isolated from the culture broth of Amycolaptosis sp. NF-κB is a critical regulatory protein that activates the transcription of a number of genes, including growth factors, angiogenesis modifiers, cell adhesion molecules and anti-apoptotic factors. As NF-κB has been shown as a good target for the new therapies such as bortezomib, we studied the effects of the new specific NFκB inhibitor, DHMEQ, to myeloma cells. In the present study, we demonstrated that DHMEQ inhibited the proliferation of human myeloma cell lines, RPMI8226 and U266 in dose- and time-dependent manners. Apoptosis was detected using fluorescein-conjugated Annexin-V by FACS. Around 45.3%of RPMI8226 and 45.2% of U266 were in apoptosis 12 hours after treatment with 10 μg/ml DHMEQ. Formation of apoptotic bodies were observed 24 hour-treatment with DHMEQ in both cell lines by Giemsa staining. In contrast, no obvious cell cycle arrest was observed with DHMEQ, indicating DHMEQ directly induces apoptosis without cell cycle arrests in these myeloma cell lines. The activation of caspase-3 in RPMI8226 and U266 cells were detected with the specific antibody against the active form of caspase-3 by FACS. When the myeloma cells were pretreated with 20 μM pan-caspase inhibitor, z-VAD-FMK, DHMEQ-induced apoptosis was inhibited by 62.1% in RPMI8226 and 71.9% in U266 cells, indicating DHMEQ-induced apoptosis was caspase-dependent. The binding activities of nuclear NF-κB protein to the oligonucleotides including NF-κB binding sites was suppressed by 81.9% in RPMI8226 and 69.0% in U266 1 hour after treatment with DHMEQ. NF-κB protein seemed more accumulated in cytoplasm of myeloma cells after treatment with DHMEQ under the confocal microscope, indicating DHMEQ prevents the translocation of NF-κB protein into the nucleus. Bcl-XL is the anti-apoptotic factor and its transcription is regulated by NF-κB. However, the expression level of Bcl-XL protein was not altered 24 hours after treatment with DHMEQ in RPMI8226 and U266. We also studied the effects of DHMEQ to the patient materials. We found that DHMEQ induced apoptosis in CD138-positive plasma cells from the myeloma patients (n=3), demonstrating that DHMEQ is also effective for primary cells. We previsously developed the model of human multiple myeloma by simply injecting U266 cells into the tail vein of the immunodeficient NOG mice. This myeloma model demostrated the massive osteolytic lesions and hind leg paralysis around 7 weeks after transplantation. We did not observe any invasion of U266 cells into other organs except bone marrow. As NF-κB regulates the proliferation of myeloma cells and osteoclasts, we expect DHMEQ will inhibit the tumor growth and prevent pathological fractures by inducing apoptosis in both myeloma cells and osteoclasts in vivo. We are currently evaluating the in vivo efficacies of DHMEQ using this experimental animal model of multiple myeloma. In conclusion, we demonstrated that DHMEQ targets NF-κB and induces apoptosis in myeloma cells through caspase-dependent pathways.

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

Blood ◽  
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

scholarly journals A Role for Syntenin-1 in Multiple Myeloma Cell Survival

Blood ◽  
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.

Sphingolipids as a novel target for the treatment of multiple myeloma.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e19534-e19534
Author(s):  
Yubin Kang ◽  
Jagadish Kummetha Venketa
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Line ◽  
Cell Lines ◽  
Apoptotic Cell ◽  
Myeloma Cell ◽  
Sphingolipid Metabolism ◽  
Myeloma Cell Line ◽  
Myeloma Cells ◽  
Novel Target

e19534 Background: Multiple myeloma (MM) is the second most common hematological malignancy in the United States and accounts for ~10,600 deaths annually. MM remains an incurable disease and almost all patients will eventually relapse and become refractory to currently available therapeutic agents. There is an unmet need for better understanding the disease’s molecular pathways and for identifying novel therapeutic targets. Sphingolipid metabolism is being increasingly recognized as a key pathway in tumor cell proliferation and in tumor sensitivity to anticancer drugs. We hypothesize that altered sphingolipid metabolism plays an important role in the pathogenesis of MM, thus providing a novel target in the treatment of MM. Methods: We first assayed sphingolipid metabolism including sphingolipid metabolites and sphingolipid metabolizing genes in myeloma cell lines, in freshly isolated human primary CD138+myeloma cells, and in publically available dataset. We then tested the efficacy of the selective SK2 inhibitor (ABC294640) and the SK2 shRNA in killing myeloma cells in vitro. Results: 1) Compared to immortalized B cells, the levels of pro-apoptotic ceramides were decreased whereas the proliferative sphingosine 1-phosphate (S1P) was increased in myeloma cell lines. 2) The expression of several key sphingolipid-metabolizing genes including sphingosine kinase (SK) 1 and 2 was altered in freshly isolated human primary bone marrow myeloma cells and in publically available microarray dataset. 3) The selective SK2 inhibitor (ABC294640) induces apoptotic cell death and inhibits myeloma cell growth with an IC50of ~20 μM in 9 myeloma cell lines. 4) Interestingly, OPM-1 myeloma cell line was extremely sensitive to ABC294640 with an IC50of <5 µM whereas U266 myeloma cell line was resistant to ABC294640. SK2 shRNA induced apoptotic cell death in OPM-1, but not in U266 cells. We are currently investigating the molecular mechanisms underlying the resistance of U266 myeloma cells to ABC294640. Conclusions: Our data demonstrated that sphingolipid metabolism provides an attractive target in the treatment of refractory/relapased multiple myeloma.

Mcl-1 Is Overexpressed in Multiple Myeloma and Correlates with Disease Severity.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1419-1419
Author(s):  
Soraya Wuilleme-Toumi ◽  
Nelly Robillard ◽  
Patricia Gomez-Bougie ◽  
Philippe Moreau ◽  
Steven Le Gouill ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Disease Severity ◽  
Cell Lines ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Lymphocytic Leukemia ◽  
Myeloma Cells

Abstract Multiple Myeloma (MM) is a fatal malignancy of B-cell origin characterized by the accumulation of plasma cells within the bone marrow. The expression of the pro-survival members of the Bcl-2 family has been shown to be a key process in the survival of myeloma cells. More particularly, Mcl-1 expression turned out to be critical for their survival. Indeed, knockdown of Mcl-1 by antisenses induces apoptosis in myeloma cells. Finally, Mcl-1 was found to be the only anti-apoptotic Bcl-2 family member which level of expression was modified by cytokine treatment of myeloma cells. For these reasons, we have evaluated the expression of Mcl-1 in vivo in normal, reactive and malignant plasma cells (PC) i.e., myeloma cells from 55 patients with MM and 20 human myeloma cell lines using flow cytometry. We show that Mcl-1 is overexpressed in MM in comparison with normal bone marrow PC. Forty-seven percent of patients with MM at diagnosis (p=.017) and 80% at relapse (p=.014 for comparison with diagnosis) overexpress Mcl-1. Of note, only myeloma cell lines but not reactive plasmocytoses have abnormal Mcl-1 expression, although both plasmocyte expansion entities share similar high proliferation rates (&gt;20%). Of interest, Bcl-2 as opposed to Mcl-1, does not discriminate malignant from normal PC. This shows that the overexpression of Mcl-1 is clearly related to malignancy rather than to proliferation. It will be important to know whether the overexpression of Mcl-1 is related to an abnormal response to cytokines like Interleukin-6 or to mutations of the promoter of the Mcl-1 gene as already described in B chronic lymphocytic leukemia. Finally, level of Mcl-1 expression is related to disease severity, the highest values being correlated with the shortest event-free survival (p=.01). In conclusion, Mcl-1 which has been shown to be essential for the survival of human myeloma cells in vitro is overexpressed in vivo in MM and correlates with disease severity. Mcl-1 represents a major therapeutical target in MM.

Tetraspanin Overexpression Induces Multiple Myeloma Cell Death.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5067-5067
Author(s):  
Tali Tohami ◽  
Liat Drucker ◽  
Judith Radnay ◽  
Hava Shapiro ◽  
Michael Lishner
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Lines ◽  
Caspase 3 ◽  
Annexin V ◽  
Myeloma Cell ◽  
Transfected Cells ◽  
Over Expression ◽  
Rpmi 8226

Abstract Background: Medullary and extra-medullary dissemination of multiple myeloma (MM) cells involves cell-cell and cell-extracellular matrix (ECM) interactions. Proteins coordinating these intricate networks regulate the signaling cascades in a spatial and time dependent manner. Tetraspanins facilitate multiprotein complexing in defined membranal microdomains and select family members have been identified as metastasis suppressors. In preliminary studies, we observed that tetraspanins CD82, frequently down regulated or lost at the advanced clinical stages of various cancers, was absent in MM (8 BM samples, 5 cell lines) and CD81, characteristically expressed in leukocytes plasma membranes, was under-expressed (4/8 BM samples, 4/5 cell lines). We aimed to investigate the consequences of CD81 and CD82 over-expression in myeloma cell lines. Methods: CAG and RPMI 8226 were transfected with pEGFP-N1/C1 fusion vectors of CD81 and CD82. Transfected cells were assessed for - cell morphology (light and fluorescent microscope); cell survival (eGFP+/PI- cells); cell death (Annexin V/7AAD, pre-G1, activated caspase-3 (IC), caspase dependence with pan caspase inhibitor z-VAD-fmk); cell cycle (PI staining). Results: CD82 induced cell death was determined by morphologic characteristics in stably transfected CAG cells (50%) compared to their mock-transfected counterparts (8%) (p&lt;0.05). Activated caspase-3 was also detected (40% of the CD82 transfected cells) (p&lt;0.05). In CD82 transiently transfected MM cell lines a reduced fraction of surviving cells was observed compared to mocks (~60%) (p&lt;0.05) yet, no increases in pre-G1 or Annexin V+/7AAD- subgroups were observed. Moreover, CD82 induced cell death could not be inhibited by the use of z-VAD-fmk. CD82 transfection did not affect the cell cycle of CAG and RPMI 8226 lines. CD81 stably transfected cell lines (CAG and RPMI 8226) could not be established. Indeed, in transiently transfected cells we determined a massive rate of CD81 induced cell death. This is demonstrated in a surviving fraction of only 10% CAG cells and 30% RPMI 8226 (compared to mock) (p&lt;0.05). The CD81 transfected cells were negative for PS exposure, pre-G1 sub-population, or inhibition of death with z-VAD-fmk. The death inducing effect of both tetraspanins in the two cell lines was evident with the pEGFP-N1 orientation vector only. Conclusions: CD81 and CD82 over-expression in MM cell lines causes cell death. Based on the restriction of the killing effect to the pEGFP-N1 clone it may be speculated that its implementation is either dependent on the interactions of the N1 tetraspanin terminus or the proteins’ conformation. It is of interest that CD81 though normally expressed in RPMI 8226 still induced cell death when over-expressed, possibly indicative of ’negative signaling’. Tetraspanins’ suppressive effects on adhesion, motility, and metastasis in solid tumors combined with its capacity to induce myeloma cell death underscore the significance of its absence in MM cell lines and patients. We suspect that a better understanding of CD81/82 mediated signaling pathways will promote future treatment of myeloma cell in their microenvironment. Current studies designed to assess the involvement of oxidative stress in CD81/CD82 induced death are underway.

Cucurbitacin I (JSI-124) Has Potent Anti-Myeloma Effects Independent of Its Inhibition of JAK2-Induced STAT3 Activation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2521-2521
Author(s):  
Huihui Ma ◽  
Judith Ziegler ◽  
Ren-Tien Feng ◽  
Suzanne Lentzsch ◽  
Markus Mapara
Keyword(s):  
Bone Marrow ◽  
Cell Lines ◽  
Caspase 3 ◽  
Myeloma Cell ◽  
Janus Kinase ◽  
Cell Counting ◽  
Myeloma Cells ◽  
Induction Of Apoptosis ◽  
Rpmi 8226 ◽  
The Impact

Abstract Multiple myeloma (MM) is a plasma cell proliferative disorder that results in considerable morbidity and mortality. JSI-124 is a plant natural product identified previously as Cucurbitacin I, isolated from various plant families such as the Cucurbitaceae and Cruciferae and has been recently described as a specific inhibitor of Janus Kinase-2 (JAK-2)/signal transducer and activator of transcription-3 (STAT3). Based on the critical role of the IL-6/STAT3 pathway in MM we studied the effects of JSI-124 on different MM cells in vitro. Different human myeloma cell lines including MM1.S, IM9, OPM-2, RPMI-8226, ARH77 in addition to the murine 5TGM myeloma cell lines were incubated with increasing concentrations of JSI-124. The impact of JSI-124 on cell proliferation, cell cycle and induction of apoptosis was studied using [3H]-Thymidine incorporation, cell counting, flow cytometry and Annexin/PI staining and caspase 3, 8 and 9 activation. JSI-124 was able to inhibit proliferation and induce apoptosis in several MM cell lines, including MM1.S, IM9, OPM-2, RPMI-8226, ARH77, U266 and 5TGM in a dose- and time-dependent manner. JSI-124 lead to activation of caspase 3, 8 and 9 indicating involvement of both extrinsic and intrinsic apoptotic pathways. JSI-124-mediated induction of apoptosis was independent of JAK2/STAT3 inhibition as MM1.S and 5TGM cells, which lack constitutive STAT3 (Tyr705) activation were equally sensitive to JSI-124 compared to U266 cells which show a constitutive STAT3 Tyr705 phosphorylation. However, JSI-124 treatment was able to abrogate IL-6 and bone marrow stroma (BMSC)-induced STAT3 (Tyr705) activation in MM1.S cells. In addition we were able to observe JSI-124 dependent inhibition of constitutive STAT3 (Ser727) activation in MM cell lines. To further delineate the mechanism underlying its anti-myeloma effects we studied the impact of JSI-124 treatment on NF-κB, MAPK and PI3K pathways. Indeed, JSI-124 treatment resulted in inhibition of p-p65, p-MEK1,2 and p-Akt underscoring the effect of JSI-124 on STAT3-independent signaling. Our results indicate that JSI-124 is a powerful direct inhibitor of myeloma cells blocking constitutive and IL-6/BMSC-dependent STAT3 activation in addition to STAT3 independent signaling pathways. JSI-124 might therefore serve as a potent novel anti-myeloma agent targeting both myeloma cells and its bone marrow microenvironment. Further studies are warranted to evaluate the in vivo efficacy of JSI-124 and identify the STAT3 independent pathways contributing to myeloma cell growth and induction of apoptosis.

A Novel Mouse Model of Multiple Myeloma Representative of Human Disease and Its Use in Preclinical Therapeutic Assessment

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2907-2907
Author(s):  
Rosemary A Fryer ◽  
Timothy J Graham ◽  
Emma M Smith ◽  
Brian A Walker ◽  
Gareth J Morgan ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Human Condition ◽  
Myeloma Cells ◽  
Treatment Groups ◽  
Hyperintense Signal

Abstract Abstract 2907 In order to aid the pre-clinical development of novel therapeutics for multiple myeloma, an in vivo model which recapitulates the human condition in particular tumor growth patterns and response to treatment is required. An important feature of such a model is the interaction of the myeloma cells with the bone marrow microenvironment as this is known to modulate tumor activity and protect against drug-induced apoptosis. We have developed a model with myeloma restricted to the bone marrow, which proceeds rapidly from initial inoculation to disease progression, and possesses a range of chemo-sensitive markers with which to monitor anti-tumor response. Female NOD/SCID γcnull mice were injected inta-osseously with luciferase-tagged myeloma cell lines. Disease progression was monitored weekly by bioluminescent imaging (BLI) and measurement of paraprotein levels (ELISA). These methods were compared to histological assessment of tumor infiltration and MRI which provided a quantitative measurement of progression. On T2-weighted images tumor was identified as a hyperintense signal enclosed within cortical bone. Tumor burden was quantified from regions of interest drawn on the periphery of the hyperintense signal. Luciferase-tagged cells engrafted by 3 weeks at the injection site and progressed to the femurs, spine and pelvis from week 4. BLI showed a significant increase in radiance from 5.6×105 to 43.0×105p/s/cm2/sr between weeks 5 and 7 (p<0.05). Quantification of tumor volume by MRI showed a significant increase from 6.4mm3 to 27.6mm3 between weeks 4 and 8 (p<0.05) and μCT demonstrated lytic disease. Serum levels of Igλ increased from 860ng/ml to 4325ng/ml during this period (p<0.05), which mirrored the changes seen with BLI and MRI. Flow cytometry and histology confirmed the confinement of CD138 positive myeloma cells within the bone. These results indicate successful engraftment of human myeloma cell lines with induction of myeloma in a pattern similar to the human condition. We have adapted this model to study primary patient material. 10 mice were implanted with samples from 3 cases of plasma cell leukemia with complex cytogenetics. 5 of these developed myeloma confined to the bone marrow, 2 with additional plasmacytoma localized at the injection site, over a period of 1–5months. We have characterized the original patient cells with gene expression, SNP based gene mapping and have characterized the nature of the engrafted cells using similar technology. We have also shown the model is suitable for preclinical assessment of anti-myeloma agents using bortezomib and a novel aminopeptidase inhibitor, tosedostat (CHR-2797). Non-treated mice displayed a significant increase in radiance from 16.13×105 to 69.00×105p/s/cm2/sr (p<0.01). In comparison, in the bortezomib and tosedostat treated groups no significant increase in radiance was seen (bortezomib: 5.22×105 to 1.12×105 p/s/cm2/sr; tosedostat: 9.92×105 to 13.78×105p/s/cm2/sr). Paraprotein levels mimicked these changes in BLI. At the end of treatment Igλ levels in control, bortezomib and tosedostat treated mice were 2473.7, 132.5 and 923.0ng/ml, respectively. Igλ levels in both treatment groups were significantly different from control (p<0.001). Average tumor volumes derived from MRI were significantly different in bortezomib (14.7mm3) and tosedostat treated (23.4mm3) groups compared to non-treatment (33.0mm3). The volumes for the bortezomib treated group showed no significant difference from control mice. In addition, there was a decrease in CD138 expression by flow cytometry in bone aspirates from treatment groups compared to control which was mirrored in histological samples. In conclusion using both myeloma cell lines and primary patient cells, we have developed a model which recapitulates human myeloma with secretion of paraprotein, disease confined to the bone marrow, lytic bone lesions and spinal compression. In addition, this model is suitable for assessing the efficacy of novel therapeutics in vivo, using a number of non-invasive tumor markers such as BLI and MRI. Disclosures: Morgan: J&J: Honoraria, Speakers Bureau. Davies:J&J: Honoraria, Speakers Bureau.

Sphingolipids As a Novel Target For The Treatment Of Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3163-3163 ◽  
Author(s):  
Jagadish Kummetha Venkata ◽  
Robert K Stuart ◽  
Luciano J Costa ◽  
Ningfei An ◽  
Houjian Cai ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Myeloma Cell ◽  
Sphingolipid Metabolism ◽  
Myeloma Cells ◽  
S1p Receptors

Abstract Introduction Multiple Myeloma (MM) is the second most common hematological malignancy in the United States and accounts for ∼10,600 deaths annually. MM remains an incurable disease and almost all patients will eventually relapse and become refractory to currently available therapeutic agents. There is an unmet need for better understanding of the disease’s molecular pathways and identifying novel therapeutic targets. Sphingolipid metabolism is being increasingly recognized as a key pathway in cancer biology. In particular, sphingosine kinases (SK1 and SK2) provide a potential site for manipulation of the ceramide / sphingosine 1-phosphate (S1P) rheostat that regulates the balance between tumor cell proliferation and apoptosis, as well as tumor sensitivity to drugs. Currently, very little is known about sphingolipid metabolism in MM. We herein for the first time provide a detailed analysis of sphingolipid metabolism in MM and demonstrate the potential of targeting SK2 for the treatment of MM. Methods We first quantified sphingolipid metabolites and sphingolipid metabolizing genes in myeloma cell lines, in freshly isolated human primary CD138+ myeloma cells, and in a publically available gene expression dataset from MM patients. We then tested the anti-myeloma activity of SK2-specific shRNA and determined the efficacy of a selective SK2 inhibitor (ABC294640) in killing myeloma cell lines and primary human myeloma cells in vitro. The mechanistic pathway of apoptosis was analyzed by immunoblotting and flowcytometry. MM cell lines stably expressing luciferase and eGFP were generated for xenograft experiments and for in vitro co-cultures with stromal cells. Results From the publically available GSE6477 microarray data set, we found that one third of the genes involved in sphingolipid metabolism were significantly different in CD138+ MM cells from newly diagnosed MM patients compared to normal individuals, including SK2 and S1P receptors. In 5 MM cell lines compared to immortalized B cells (IBC), 19 key sphingolipid metabolites were measured, and we found that ceramides were significantly reduced whereas S1P was significantly increased. mRNA analyses of 11 sphingolipid metabolizing genes including S1P receptors in 7 MMs showed that SK1, SK2, and alkaline ceramidases were significantly increased compared to IBC. Furthermore, we isolated CD138+ myeloma cells from 21 MM patients and found that 13 of the patients had higher SK2 expression in CD138+ MM cells compared to CD138-cells. These data demonstrated abnormal sphingolipid metabolism and dys-regulated SK2 in myeloma cells. We generated SK2-specific shRNA and found that SK2 shRNA down-regulated SK2 mRNA, inhibited proliferation, and induced death in myeloma cells, suggesting that SK2 is important in myeloma cell survival. We then tested the efficacy of ABC294640 (the most-advanced, non-lipid SK2 inhibitor) in 6 MM cell lines. ABC294640 inhibited myeloma cell growth with an IC50s of ∼30 μM, including steroid-resistant and doxorubicin-resistant myeloma cells. ABC294640 inhibited MM cell growth as early as 6 hours after exposure and induced apoptotic cell death as demonstrated by Annexin V staining, PARP cleavage and caspase 9 activation. ABC294640 inhibited primary human CD138+MM cells with the same efficacy as with MM cell lines, demonstrating the potential of ABC294640 for the treatment of MM. Additionally, we found that blocking S1P receptors with FTY720 (a S1PR agonist with receptor degradation) induced apoptosis in MM cells. We performed extensive mechanistic and signaling pathway analyses and found that ABC294640 inhibited Mcl-1 and C-Myc expression, but had no effects on Bcl2. Furthermore, ABC294640 induced cell death by directing Mcl-1 to proteosomal degradation. MM is dependent on the bone marrow niche microenvironment for survival and progression. We found that ABC294640 was effective in inducing apoptosis in MM cells even in the presence of stromal cells. Finally, we are currently testing the in vivo effect of ABC294640 alone and in combination with bortezomib, thalidomide and dexamethasone in MM xenograft model transplanted with MM cells stably expressing luciferase. Our early preliminary results were encouraging. Conclusion Our data demonstrate that sphingolipid metabolism is abnormal and provides an attractive target in the treatment of refractory/relapsed MM. Disclosures: Costa: Otsuka: Research Funding.

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