scholarly journals Macrophages are an abundant component of myeloma microenvironment and protect myeloma cells from chemotherapy drug–induced apoptosis

Blood ◽  
2009 ◽  
Vol 114 (17) ◽  
pp. 3625-3628 ◽  
Author(s):  
Yuhuan Zheng ◽  
Zhen Cai ◽  
Siqing Wang ◽  
Xiang Zhang ◽  
Jianfei Qian ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Survival ◽  
Stromal Cells ◽  
Myeloma Cell ◽  
Drug Induced ◽  
Myeloma Cells ◽  
Chemotherapy Drug ◽  
Response To Chemotherapy ◽  
Induced Apoptosis

Abstract Multiple myeloma remains an incurable disease. One of the major problems is that myeloma cells develop drug resistance on interaction with bone marrow stromal cells. In this study, we examined the effects of macrophages (Mφs), a type of stromal cells, on myeloma cell survival and response to chemotherapy. We showed that Mφ, in particular tumor-associated Mφ, is a protector of myeloma cells. The protective effect was dependent on direct contact between Mφs and myeloma cells. Mφs protected both myeloma cell lines and primary myeloma cells from spontaneous and chemotherapy drug-induced apoptosis by attenuating the activation and cleavage of caspase-dependent apoptotic signaling. These findings are clinically relevant because we found that CD68+ Mφs heavily infiltrate the bone marrow of patients with myeloma but not the bone marrow of control patients. Thus, our results indicate that Mφs may contribute to myeloma cell survival and resistance to chemotherapeutic treatment in vivo.

Interleukin-6 Enhances the Survival of Myeloma Cells by Regulating Bim Binding to Anti-Apoptotic Bcl-2 Proteins

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4024-4024
Author(s):  
Shannon M. Matulis ◽  
Jiangxia Liu ◽  
Vikas A. Gupta ◽  
Jason E. Conage-Pough ◽  
Ajay K. Nooka ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Survival ◽  
Conditioned Medium ◽  
Stromal Cells ◽  
Stromal Cell ◽  
Proteasome Inhibitors ◽  
Myeloma Cell ◽  
Bone Marrow Microenvironment ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract Abstract 4024 The survival of multiple myeloma cells in the bone marrow is largely dependent on its interactions with cellular components of the microenvironment. These interactions, in the form of cell-cell interactions and soluble factors support myeloma cell survival and allow for the mutations associated with transformation to drive plasma cell growth and proliferation. Moreover survival signals from the bone marrow microenvironment influence the response to therapeutic agents, therefore understanding the molecular basis of these interactions is necessary to improve the depth of responses to therapy in myeloma patients. Cell survival is regulated by the Bcl-2 family of proteins and we previously reported that in myeloma cells one can map which Bcl-2 protein is necessary for cell survival by determining which protein is sequestering the pro-apoptotic molecule, Bim. This could also be used to predict myeloma cell sensitivity to th Bcl-2/Bcl-xL antagonist ABT-737. While studying the response of freshly isolated patient samples to ABT-737, we found that in 40% of the samples tested (N=10) as well as in 5 myeloma cell lines, inclusion of stromal components significantly inhibited ABT-737-induced apoptosis. Thus the microenvironment can influence survival by altering the pattern of Bcl-2 dependence in cells. We have determined that a soluble factor secreted by stromal cells is necessary for this activity and now report that this factor is interleukin-6. We found that addition of conditioned medium from the HS-5 stromal line or freshly isolated bone marrow stromal cells (N=4) from myeloma patients or normal donors (N=1) to human myeloma cell lines all resulted significant resistance to ABT-737. Since all of these cells are a rich source of IL-6, we tested if the addition of recombinant IL-6 mimicked the addition of stromal cell supernatant. Indeed rIL-6 (10 ng/ml) was as potent as co-culture with HS-5 cells or addition of HS-5 or stromal cell conditioned medium at blocking ABT-737-induced apoptosis in MM.1s cells. Thus IL-6 is sufficient to block ABT-737-induced apoptosis. To demonstrate that IL-6 was necessary we determined the effect of the addition of an IL-6 neutralizing antibody on stromal cell-induced resistance to ABT-737. We found that addition of the antibody to HS-5 conditioned medium blocked resistance to ABT-737 in a dose-dependent fashion. Moreover we found that addition of anti-IL6 to a patient sample had a similar effect as removing the stromal cells on the response to ABT-737-induced death. Taken together these data suggest that IL-6 is both necessary and sufficient for regulating Bcl-2 dependence in multiple myeloma. To define the molecular basis for these findings we initially investigated the expression of the key Bcl-2 proteins involved in Bcl-2 dependence and myeloma cell survival. Despite their profound effects on ABT-737-induced apoptosis we found that neither co-culture of MM.1s cells with HS-5 cells, HS-5 conditioned medium or rIL-6 had any effect on the expression of Mcl-1, Bcl-xL or Bim. We then investigated the patterns of interaction between these proteins and found that the addition of stromal components or IL-6 resulted in a shift of Bim binding from Bcl-xL to Mcl-1. This is consistent with our previous findings that when Bim is bound to Mcl-1, myeloma cells are less sensitive to ABT-737. Finally we set out to determine how IL-6 signaling results in a change in ABT-737 sensitivity. We treated MM.1s cells with ABT-737 and IL-6 in the presence of inhibitors of the MEK/ERK, p38, PI3K/AKT, and JAK/STAT pathways. We found that only the MEK inhibitor, U0126 could re-sensitize IL-6-treated cells to ABT-737-induced death at concentrations that did not kill cells or have additive effects with ABT-737 in the absence of IL-6 (P<0.05 2-way ANOVA). Taken together, these data indicate that stromal cells regulate myeloma cell survival through IL-6 by altering Bim binding in a MEK-dependent fashion. This results in a cell that is highly dependent on Mcl-1. These data offer an explanation for why proteasome inhibitors are so effective in this disease. While the bone marrow microenvironment is enforcing Mcl-1 dependence, proteasome inhibitors induce the Mcl-1 inhibitor Noxa, which overcomes this activity of IL-6. Moreover these data point to potential ways of combining the targeting of Bcl-2 proteins and IL-6 signaling as a means to effectively kill myeloma cells in the bone marrow microenvironment. Disclosures: Kaufman: Millenium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Onyx Pharmaceuticals: Consultancy.

Myeloma and the Microenvironment: Macrophages Are a Protector of Myeloma Cells Apoptosis Induced by Chemotherapy Drugs.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4804-4804
Author(s):  
Jing Yang ◽  
Yuhuan Zheng ◽  
Zhen Cai ◽  
Jianfei Qian ◽  
Sungyoul Hong ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Survival ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Myeloma Cell ◽  
Marrow Stromal Cells ◽  
Apoptotic Cells ◽  
Tumor Associated Macrophages ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract Abstract 4804 Multiple myeloma is a B-cell malignancy characterized by the proliferation of plasma cells in the bone marrow. It is the second most common hematological malignancy and is still largely incurable. One of the major problems is that myeloma cells develop drug resistance upon interaction with bone marrow stromal cells. To better understand the importance of different stromal cell components in the bone marrow microenvironment, we examined the effects of macrophages on myeloma cell survival and myeloma cell response to chemotherapy. We report here that macrophages, in particular tumor-associated macrophages obtained by culturing macrophages with myeloma cell culture supernatants, are a protector of myeloma cells. Macrophages protected both myeloma cell lines and primary myeloma cells isolated from patients from spontaneous and chemotherapy drug-induced apoptosis via attenuating the activation of caspase-dependent apoptotic signaling. The protective effect was dependent on direct contact between macrophages and myeloma cells. Although tumor-associated macrophages secreted large amounts of IL-6, which is the most important survival factor for myeloma cells, our results showed that IL-6 neutralizing antibodies fail to significantly affect the protective effects of tumor-associated macrophages. The reduced numbers of apoptotic tumor cells in the cocultures were not the result of macrophage-uptake of apoptotic cells, because macrophages with or without the ability to phagocytose apoptotic cells provide similar protection to myeloma cells against chemotherapy-induced apoptosis. These findings are clinically relevant, because we examined bone marrow biopsies of patients by immunochemical analysis and found that CD68+ macrophages are heavily infiltrated in the bone marrow (tumor bed) of patients with myeloma but not control patients. Thus, our results indicate that macrophages are an important component of the bone marrow stromal cells and may contribute to myeloma cell survival and resistance to chemotherapeutic treatment in vivo. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Plasma cells induce apoptosis of pre-B cells by interacting with bone marrow stromal cells

Blood ◽  
1996 ◽  
Vol 87 (8) ◽  
pp. 3375-3383 ◽  
Author(s):  
T Tsujimoto ◽  
IA Lisukov ◽  
N Huang ◽  
MS Mahmoud ◽  
MM Kawano
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Cell Lines ◽  
Stromal Cells ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
B Cell Survival

By using two-color phenotypic analysis with fluorescein isothiocyanate- anti-CD38 and phycoerythrin-anti-CD19 antibodies, we found that pre-B cells (CD38+CD19+) signifcantly decreased depending on the number of plasma cells (CD38++CD19+) in the bone marrow (BM) in the cases with BM plasmacytosis, such as myelomas and even polyclonal gammopathy. To clarify how plasma cells suppress survival of pre-B cells, we examined the effect of plasma cells on the survival of pre-B cells with or without BM-derived stromal cells in vitro. Pre-B cells alone rapidly entered apoptosis, but interleukin-7 (IL-7), a BM stromal cell line (KM- 102), or culture supernatants of KM-102 cells could support pre-B cell survival. On the other hand, inhibitory factors such as transforming growth factor-beta1 (TGF-beta1) and macrophage inflammatory protein- 1beta (MIP-1beta) could suppress survival of pre-B cells even in the presence of IL-7. Plasma cells alone could not suppress survival of pre- B cells in the presence of IL-7, but coculture of plasma cells with KM- 102 cells or primary BM stromal cells induced apoptosis of pre-B cells. Supernatants of coculture with KM-102 and myeloma cell lines (KMS-5) also could suppress survival of pre-B cells. Furthermore, we examined the expression of IL-7, TGF-beta1, and MIP-1beta mRNA in KM-102 cells and primary stromal cells cocultured with myeloma cell lines (KMS-5). In these cells, IL-7 mRNA was downregulated, but the expression of TGF- beta1 and MIP-1beta mRNA was augmented. Therefore, these results suggest that BM-derived stromal cells attached to plasma (myeloma) cells were modulated to secrete lesser levels of supporting factor (IL- 7) and higher levels of inhibitory factors (TGF-beta1 and MIP-1beta) for pre-B cell survival, which could explain why the increased number of plasma (myeloma) cells induced suppression of pre-B cells in the BM. This phenomenon may represent a feedback loop between pre-B cells and plasma cells via BM stromal cells in the BM.

Dexmethasone Down-Regulates Stromal Cell-Derived Factor-1 Production in Bone Marrow Stromal Cells: Implications in Myeloma Cell Biology.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2510-2510
Author(s):  
Seong-Woo Kim ◽  
Jin-Hee Hwang ◽  
Hwan-Jung Yun ◽  
Samyong Kim ◽  
Deog-Yeon Jo
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Myeloma Cell ◽  
Cxcr4 Expression ◽  
Marrow Stromal Cells ◽  
Myeloma Cells ◽  
Regulatory Effects ◽  
Stromal Cell Derived Factor ◽  
Induced Apoptosis

Abstract Stromal cell-derived factor-1 (SDF-1) plays a role in the homing of myeloma cells to bone marrow. In addition, SDF-1 modestly enhances the proliferation of myeloma cells and inhibits Dexmethasone (Dex)-induced apoptosis of the cells. Dex is currently used to treat multiple myeloma, based on its apoptic effects. In this study, we investigated the regulatory effects of Dex on SDF-1 production in bone marrow stromal cells (BMSCs) and on CXCR4 expression in myeloma cells. As previously reported, it was evident that primary myeloma cells (CD138+ cells obtained from patients with multiple myeloma) and Dex-resistant myeloma cell line RPMI8226 expressed CXCR4 and responded to SDF-1, resulting in chemotaxis. SDF-1 modestly stimulated the proliferation of primary myeloma cells and RPMI8226 cells and protected the cells from Dex-induced apoptosis. Human umbilical vein endothelial cells transduced with the SDF-1 gene using adenoviral vectors better supported the formation of cobblestone areas of primary myeloma cells and RPMI8226 cells in co-culture, similar to hematopoietic progenitor cells; this was blocked by pretreating the myeloma cells with pertussis toxin, indicating that SDF-1 plays a critical role not only in migration of the cells underneath the SDF-1-producing stromal cells but also in proliferation of the cells in contact. Dex up-regulated CXCR4 expression in RPMI8226 cells; however, its regulatory effects on CXCR4 in primary myeloma cells differed among patients. RT-PCR and Northern blot analyses revealed that Dex down-regulated SDF-1 mRNA expression in both primary BMSCs and murine stromal MS-5 cells in a dose-dependent manner. Western blot analysis and ELISA assay confirmed that Dex inhibited SDF-1 production in BMSCs. Furthermore, Dex inhibited cobblestone area formation of RPMI8226 cells in co-culture with MS-5. Interestingly, Dex up-regulated CXCR4 mRNA expression and cytoplasmic CXCR4 in BMSCs. These results indicate that Dexamethasone induces the down-regulation of SDF-1 production in BMSCs, which might mediate, at least in part, its anti-myeloma effects in vivo.

Etodolac Induces Apoptosis and Inhibits Cell Adhesion to Bone Marrow Stromal Cells in Human Myeloma Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4836-4836
Author(s):  
Satoki Nakamura ◽  
Miki Kobayashi ◽  
Kiyoshi Shibata ◽  
Naohi Sahara ◽  
Kazuyuki Shigeno ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Myeloma Cell ◽  
Marrow Stromal Cells ◽  
Myeloma Cells ◽  
Cox 2 ◽  
Induced Apoptosis

Abstract Cyclooxygenase-2 (COX-2) is reported to regulate apoptosis and to be an important cellular target for therapy. In this study, we demonstrated that etodolac, a COX-2 inhibitor, inhibited proliferation and induced apoptosis in myeloma cell lines (RPMI 8226 and MC/CAR cells), expressing the COX-2 enzyme. In both cell lines, etodolac more strongly induced apoptosis compared with thalidomide or meloxicam. Etodolac induced down-regulation of bcl-2 protein and mRNA, activation of caspase-9, -7 and -3, down-regulation of caspase inhibitors, cIAP-1 and survivin, and loss of mitochondrial membrane potential in a dose-dependent manner. In addition, our data demonstrated that when myeloma cells were coincubated with 50 mM etodolac on bone marrow stromal cells (BMSC), myeloma cell adhesion to BMSC was significantly inhibited compared with thalidomide or meloxicam coincubation, and the adhesion molecules VLA-4, LFA-1 (CD11a), CXCX4, and CD44 were suppressed on myeloma cells treated with etodolac. Moreover, we found that 100 mM R-etodolac, S-etodolac, and the combination of R- and S-etodolac, which are the stereoisomers of etodolac, slightly inhibited the proliferation of myeloma cells, while 50 to 100 mM etodolac significantly inhibited the proliferation of myeloma cells. In conclusion, our findings indicate that etodolac induced apoptosis via a bcl-2 dependent pathway, suppressed the expression of adhesion molecules, and inhibited myeloma cell adhesion to BMSC compared with thalidomide or meloxicam. Thus, the activities of etodolac potentially extend to the treatment of patients with myeloma resistant to standard chemotherapy, including thalidomide.

Dual Src/Abl Kinase Targeted Inhibition in Myeloma Microenvironment Promotes Myeloma Cell Apoptosis Both in Vitro and In Vivo.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2813-2813
Author(s):  
Karthik Ramasamy ◽  
Lee Macpherson ◽  
Ghulam J Mufti ◽  
Stephen Schey ◽  
Yolanda Calle
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
Stromal Cells ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Abl Kinase ◽  
Osteoclast Function

Abstract Abstract 2813 Poster Board II-789 Osteoclast, in addition to eroding the bone resulting in lytic lesions, enhances plasma cell proliferation and survival via direct cell to cell contact. Src family protein tyrosine kinases (SFKs) and c-Abl kinase play important role downstream of integrin adhesion receptors, and regulate the cytoskeletal organisation, cell motility and gene expression in response to cell adhesion. We hypothesised targeting SFKs and Abl kinase with the small molecule tyrosine kinase inhibitor Dasatinib has potential to reduce adhesion of plasma cells to ECM proteins in the bone marrow and modify the microenvironment by inhibiting osteoclast function, specifically bone resorption. As a result, myeloma cells could be sensitised to drugs with cytotoxic properties such as dexamethasone. Osteoclasts were generated from primary bone marrow mononuclear cells of myeloma and MGUS patients (n=10). Using Immunofluorescence, we found that Dasatinib 100nM but not dexamethasone inhibited osteoclastogenesis and disrupted the actin cytoskeletal organisation with actin clusters formed in the periphery of the cell. There was absence of actin ring formation at sealing zones which is essential for bone resorption. This effect consistently led to impaired osteoclast function, evidenced by fewer resorption pits formed on rabbit dentine slices on toluidine blue staining. Experiments were repeated ≥ 3 times. In plasma cells, the combination of dexamethasone and Dasatinib synergistically (Calcusyn software) inhibited cell proliferation at clinically relevant concentrations and induced apoptosis of human and murine myeloma cell lines alone and in cocultures with human stromal cells ( p<.001). Dasatinib alone at 200 nM concentration does not inhibit plasma cell proliferation with maximal serum concentration achieved in Phase I CML trials being 180nM. Additionally, Dasatinib and Dexamethasone in combination inhibited secretion of IL-6 but not MIL -1 alpha in stromal cell cocultures. Dasatinib but not dexamethasone significantly inhibited adhesion of myeloma cell lines on Fibronectin despite integrin activation with Magnesium EGTA. This effect was mediated through down regulation of both Src and Abl phosphorylation. Both Dasatinib and Dexamethasone inhibited adhesion of PC on stromal cells and osteoclasts. Taken together, our in vitro results suggest that Dasatinib and dexamethasone could be an effective therapeutic combination with Dasatinib impairing adhesion of plasma cells to the bone marrow microenvironment as well as osteoclast function and resultant bone disease thereby sensitising myeloma cells to the cytotoxic effect of dexamethasone. We have also established that the combination of Dasatinib 75mg/kg and dexamethasone 1mg/kg is not toxic to C57BL/KaLwRij mice. The anti-myeloma efficacy of these drugs alone and in combination is being currently studied. The combination of Dasatinib 100 mg OD days 1-28 and Dexamethasone 20mg OD on Day 1-4, 15-18 has resulted in a partial response (EBMT criteria) in 2 multiply relapsed and steroid refractory myeloma patients without significant toxicity. Serum calcium levels fell commensurate with disease response and we are currently performing experiments to analyse the effect of the drug combination on osteoclast function in vivo. These findings warrant exploring this drug combination in steroid resistant myeloma and patients with extensive skeletal disease prospectively in a phase I/II trial. Disclosures: Off Label Use: Dasatinib is not licensed for Myeloma.

scholarly journals Resistin Induces Multidrug Resistance in Myeloma By Inhibiting Cell Death and Upregulating ABC Transporter Expression

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5656-5656
Author(s):  
Jianan Pang ◽  
Qiaofa Shi ◽  
Zhiqiang Liu ◽  
Jin He ◽  
Huan Liu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Protective Effect ◽  
Abc Transporters ◽  
Conflicts Of Interest ◽  
Myeloma Cell ◽  
Long Term Outcome ◽  
Myeloma Cells ◽  
Chemotherapy Drugs ◽  
Response To Chemotherapy ◽  
Induced Apoptosis

Abstract Chemoresistance is a major hurdle in multiple myeloma. Most patients are prone to develop resistance to a wide spectrum of anticancer agents, significantly hampers the patients' long term outcome. Many studies point to bone marrow microenvironment as an important player in myeloma chemoresistance, in which marrow stromal cells and stromal-secreted soluble factors are shown to promote myeloma cell growth and survival. Our previous study has demonstrated that marrow-derived adipocytes protect myeloma cells against chemotherapy-induced apoptosis through adipocyte-secreted adipokines, one of such is leptin. However, the level of leptin expression in myeloma patients is not significantly changed, indicating the involvement of additional adipokines in this process. Interestingly, in a clinical study, an elevation of the adipokine resistin in the serum of myeloma patients after thalidomide treatment were observed as compared with that in patients before treatment, suggesting a potential role of this adipokine in response to chemotherapy. As a 12.5-kDa hormone that is mainly secreted by adipocytes and also secreted by other cells, resistin has a function in production of inflammatory cytokines that are important for cancer development. We thus hypothesized that resistin protects myeloma cells against chemotherapy. In our experiments, human myeloma cell lines and primary myeloma cells isolated from patient bone marrow aspirates were cultured in medium with addition of the recombinant human resistin and chemotherapy drugs melphalan or bortezomib for 24 hours. Cells without resistin served as a control. After cultures, an annexin-V binding assay for assessing apoptosis, western blot analysis for assessing cleavage of caspases and phosphorylation of signaling kinases, and the eFluxx-ID Gold uptake assay for examining ABC transporters activity were performed. In the animal study, myeloma-bearing SCID mice were treated with or without resistin and/or melphalan. Our results showed that resistin treatment reduced melphalan- or bortezomib-induced apoptosis both in vitro and in vivo. This protective effect has been further confirmed by the reduced cleavage of caspase-9, caspase-3, and poly (ADP-ribose) polymerase in myeloma cells. Mechanistic studies showed that culturing myeloma cells with resistin upregulated expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL and downregulated expression of the pro-apoptotic protein Bax via the NF-kB and the PI3K/Akt signaling pathways. Addition of resistin also reduced the intracellular accumulation of eFluxx-ID gold fluorescence in myeloma cells ARP-1 and MM.1S, when compared to that in cells without resistin. In addition, resistin significantly increased the mRNA and protein expression of ATP-binding cassette (ABC) transporters in myeloma cells by downregulating the expression of DNA methyltransferase 1 and 3a, and CpG methylation in the promoters of ABC transporters. Thus, our study demonstrates that resistin is a novel factor contributing to myeloma chemoresistance, and also implicates that disruption of its protective effect can be a potential strategy to improve current chemotherapy in patients and prolong survival. Disclosures No relevant conflicts of interest to declare.

scholarly journals A Method for Measurement of Drug Sensitivity of Myeloma Cells Co-Cultured with Bone Marrow Stromal Cells

2013 ◽  
Vol 18 (6) ◽  
pp. 637-646 ◽  
Author(s):  
Kristine Misund ◽  
Katarzyna A. Baranowska ◽  
Toril Holien ◽  
Christoph Rampa ◽  
Dionne C. G. Klein ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Survival ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Large Scale ◽  
Stromal Cell ◽  
Marrow Stromal Cells ◽  
Cell Nuclei ◽  
Myeloma Cells

The tumor microenvironment can profoundly affect tumor cell survival as well as alter antitumor drug activity. However, conventional anticancer drug screening typically is performed in the absence of stromal cells. Here, we analyzed survival of myeloma cells co-cultured with bone marrow stromal cells (BMSC) using an automated fluorescence microscope platform, ScanR. By staining the cell nuclei with DRAQ5, we could distinguish between BMSC and myeloma cells, based on their staining intensity and nuclear shape. Using the apoptotic marker YO-PRO-1, the effects of drug treatment on the viability of the myeloma cells in the presence of stromal cells could be measured. The method does not require cell staining before incubation with drugs, and less than 5000 cells are required per condition. The method can be used for large-scale screening of anticancer drugs on primary myeloma cells. This study shows the importance of stromal cell support for primary myeloma cell survival in vitro, as half of the cell samples had a marked increase in their viability when cultured in the presence of BMSC. Stromal cell–induced protection against common myeloma drugs is also observed with this method.

scholarly journals An inhibitor of the EGF receptor family blocks myeloma cell growth factor activity of HB-EGF and potentiates dexamethasone or anti–IL-6 antibody-induced apoptosis

Blood ◽  
2004 ◽  
Vol 103 (5) ◽  
pp. 1829-1837 ◽  
Author(s):  
Karène Mahtouk ◽  
Michel Jourdan ◽  
John De Vos ◽  
Catherine Hertogh ◽  
Geneviève Fiol ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Growth Factor ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Egf Receptor ◽  
Myeloma Cell ◽  
Factor Activity ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract We previously found that some myeloma cell lines express the heparin-binding epidermal growth factor–like growth factor (HB-EGF) gene. As the proteoglycan syndecan-1 is an HB-EGF coreceptor as well as a hallmark of plasma cell differentiation and a marker of myeloma cells, we studied the role of HB-EGF on myeloma cell growth. The HB-EGF gene was expressed by bone marrow mononuclear cells in 8 of 8 patients with myeloma, particularly by monocytes and stromal cells, but not by purified primary myeloma cells. Six of 9 myeloma cell lines and 9 of 9 purified primary myeloma cells expressed ErbB1 or ErbB4 genes coding for HB-EGF receptor. In the presence of a low interleukin-6 (IL-6) concentration, HB-EGF stimulated the proliferation of the 6 ErbB1+ or ErbB4+ cell lines, through the phosphatidylinositol 3-kinase/AKT (PI-3K/AKT) pathway. A pan-ErbB inhibitor blocked the myeloma cell growth factor activity and the signaling induced by HB-EGF. This inhibitor induced apoptosis of patients'myeloma cells cultured with their tumor environment. It also increased patients' myeloma cell apoptosis induced by an anti–IL-6 antibody or dexamethasone. The ErbB inhibitor had no effect on the interaction between multiple myeloma cells and stromal cells. It was not toxic for nonmyeloma cells present in patients' bone marrow cultures or for the growth of hematopoietic progenitors. Altogether, these data identify ErbB receptors as putative therapeutic targets in multiple myeloma.

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