Markers of endothelial glycocalyx dysfunction in Clarkson disease

BACKGROUND

Clarkson disease (monoclonal gammopathy-associated idiopathic systemic capillary leak syndrome, ISCLS) is a rare idiopathic condition marked by transient, relapsing-remitting episodes of systemic microvascular hyper-permeability, which liberates plasma fluid and macromolecules into the peripheral tissues. This pathology manifests clinically as the abrupt onset of hypotensive shock, hemoconcentration, and hypoalbuminemia.

METHODS

We analysed endothelial glycocalyx (eGCX)-related markers in plasma from patients with ISCLS during acute disease flares and convalescence by ELISA and comprehensive proteomic profiling. We evaluated eGCX-related components and gene expression in cultured endothelial cells using RNA-sequencing, real-time PCR, and fluorescence staining.

RESULTS

Serum levels of eGCX-related core components including hyaluronic acid (HA) and the core proteoglycan soluble syndecan-1 (sCD138) were elevated at baseline and during acute ISCLS flares. Serial measurements demonstrated that sCD138 levels peaked during the recovery (post-leak) phase of the illness. Proteomic analysis of matched acute and convalescent ISCLS plasma revealed increased abundance of eGCX-related proteins, including glypicans, thrombospondin-1 (TSP-1), and eGCX-degrading enzymes in acute compared to remission plasma. Abundance of endothelial cell damage markers did not differ in acute and baseline plasma. Expression of several eGCX-related genes and surface carbohydrate content in endothelial cells from patients with ISCLS did not differ significantly from that observed in healthy control cells.

CONCLUSIONS

eGCX dysfunction, but not endothelial injury, may contribute to clinical symptoms of acute ISCLS. Serum levels of of eGCX components including sCD138 may be measured during acute episodes of ISCLS to monitor clinical status and therapeutic responses.

Highly expressed genes in multiple myeloma cells - what can they tell us about the disease?

Cancer cells can convert proto‐oncoproteins into oncoproteins by increasing the expression of genes that are oncogenic when expressed at high levels. Such genes can promote oncogenesis without being mutated. To find overexpressed genes in cancer cells from patients with multiple myeloma, we retrieved mRNA expression data from the CoMMpass database and ranked genes by their expression levels. We grouped the most highly expressed genes based on a set of criteria and we discuss the role a selection of them can play in the disease pathophysiology. The list was highly concordant with a similar list based on mRNA expression data from the PADIMAC study. Many well‐known “myeloma genes” such as MCL1, CXCR4, TNFRSF17, SDC1, SLAMF7, PTP4A3, and XBP1 were identified as highly expressed, and we believe that hitherto unrecognized key players in myeloma pathogenesis are also enriched on the list. Highly expressed genes in malignant plasma cells that were absent or expressed at only a low level in healthy plasma cells included IFI6, IFITM1, PTP4A3, SIK1, ALDOA, ATP5MF, ATP5ME, and PSMB4. The ambition of this article is not to validate the role of each gene but to serve as a guide for studies aiming at identifying promising treatment targets.

Phosphatases of regenerating liver are key regulators of metabolism in cancer cells - role of Serine/Glycine metabolism

PURPOSE OF REVIEW

Phosphatases of regenerating liver (PRL) are dual-specificity phosphatases and comprise three members, PRL-1, -2 and -3. Despite the importance of PRLs as oncoproteins, there is no consensus function for this family of phosphatases. In the current review paper, we summarize recent findings on the role of PRLs in metabolic regulation.

RECENT FINDINGS

Reprogramming of cellular metabolism is a cancer hallmark. Glucose is the major source of energy in cells. Glucose metabolism occurs through the glycolysis and can continue through the pathways such as serine synthesis pathway or the tricarboxylic acid cycle (TCA). Magnesium (Mg2+), the second most abundant cation in cells, plays an essential role in energy production by acting as a cofactor for most enzymes involved in glycolysis and in TCA. Recent findings have shown that the PRL family has a role in metabolic reprogramming mediated by (1) Mg2+ homeostasis, (2) shifting the energy source preference to glucose consumption and fueling serine/glycine pathway and (3) regulating PI3 kinase/Mammalian target of rapamycin complex. Both the phosphatase and nonphosphatase activity of PRLs appear to be important for its oncogenic role.

SUMMARY

The PRL family contributes to the metabolic plasticity of cancer cells and, thereby, allows cancer cells to meet the high metabolic demands required for cell proliferation.

Inhibition of Cytosolic Phospholipase A2α Induces Apoptosis in Multiple Myeloma Cells

Cytosolic phospholipase A2α (cPLA2α) is the rate-limiting enzyme in releasing arachidonic acid and biosynthesis of its derivative eicosanoids. Thus, the catalytic activity of cPLA2α plays an important role in cellular metabolism in healthy as well as cancer cells. There is mounting evidence suggesting that cPLA2α is an interesting target for cancer treatment; however, it is unclear which cancers are most relevant for further investigation. Here we report the relative expression of cPLA2α in a variety of cancers and cancer cell lines using publicly available datasets. The profiling of a panel of cancer cell lines representing different tissue origins suggests that hematological malignancies are particularly sensitive to the growth inhibitory effect of cPLA2α inhibition. Several hematological cancers and cancer cell lines overexpressed cPLA2α, including multiple myeloma. Multiple myeloma is an incurable hematological cancer of plasma cells in the bone marrow with an emerging requirement of therapeutic approaches. We show here that two cPLA2α inhibitors AVX420 and AVX002, significantly and dose-dependently reduced the viability of multiple myeloma cells and induced apoptosis in vitro. Our findings implicate cPLA2α activity in the survival of multiple myeloma cells and support further studies into cPLA2α as a potential target for treating hematological cancers, including multiple myeloma.

Phosphatase of regenerating liver-3 regulates cancer cell metabolism in multiple myeloma

Cancer cells often depend on microenvironment signals from molecules such as cytokines for proliferation and metabolic adaptations. PRL-3, a cytokine-induced oncogenic phosphatase, is highly expressed in multiple myeloma cells and associated with poor outcome in this cancer. We studied whether PRL-3 influences metabolism. Cells transduced to express PRL-3 had higher aerobic glycolytic rate, oxidative phosphorylation, and ATP production than the control cells. PRL-3 promoted glucose uptake and lactate excretion, enhanced the levels of proteins regulating glycolysis and enzymes in the serine/glycine synthesis pathway, a side branch of glycolysis. Moreover, mRNAs for these proteins correlated with PRL-3 expression in primary patient myeloma cells. Glycine decarboxylase (GLDC) was the most significantly induced metabolism gene. Forced GLDC downregulation partly counteracted PRL-3-induced aerobic glycolysis, indicating GLDC involvement in a PRL-3-driven Warburg effect. AMPK, HIF-1α, and c-Myc, important metabolic regulators in cancer cells, were not mediators of PRL-3's metabolic effects. A phosphatase-dead PRL-3 mutant, C104S, promoted many of the metabolic changes induced by wild-type PRL-3, arguing that important metabolic effects of PRL-3 are independent of its phosphatase activity. Through this study, PRL-3 emerges as one of the key mediators of metabolic adaptations in multiple myeloma.

PRL-3 induces a positive signaling circuit between glycolysis and activation of STAT1/2

Multiple myeloma (MM) is an incurable hematologic malignancy resulting from the clonal expansion of plasma cells. MM cells are interacting with components of the bone marrow microenvironment such as cytokines to survive and proliferate. Phosphatase of regenerating liver (PRL)-3, a cytokine-induced oncogenic phosphatase, is highly expressed in myeloma patients and is a mediator of metabolic reprogramming of cancer cells. To find novel pathways and genes regulated by PRL-3, we characterized the global transcriptional response to PRL-3 overexpression in two MM cell lines. We used pathway enrichment analysis to identify pathways regulated by PRL-3. We further confirmed the hits from the enrichment analysis with in vitro experiments and investigated their function. We found that PRL-3 induced expression of genes belonging to the type 1 interferon (IFN-I) signaling pathway due to activation of signal transducer and activator of transcription (STAT) 1 and STAT2. This activation was independent of autocrine IFN-I secretion. The increase in STAT1 and STAT2 did not result in any of the common consequences of increased IFN-I or STAT1 signaling in cancer. Knockdown of STAT1/2 did not affect the viability of the cells, but decreased PRL-3-induced glycolysis. Interestingly, glucose metabolism contributed to the activation of STAT1 and STAT2 and expression of IFN-I-stimulated genes in PRL-3-overexpressing cells. In summary, we describe a novel signaling circuit where the key IFN-I-activated transcription factors STAT1 and STAT2 are important drivers of the increase in glycolysis induced by PRL-3. Subsequently, increased glycolysis regulates the IFN-I-stimulated genes by augmenting the activation of STAT1/2.

Analysis of Intra-Tumoral Macrophages and T Cells in Non-Small Cell Lung Cancer (NSCLC) Indicates a Role for Immune Checkpoint and CD200-CD200R Interactions

Non-small cell lung carcinoma (NSCLC) is one of the most commonly diagnosed cancers and a leading cause of cancer-related deaths. Immunotherapy with immune checkpoint inhibitors shows beneficial responses, but only in a proportion of patients. To improve immunotherapy in NSCLC, we need to map the immune checkpoints that contribute immunosuppression in NSCLC-associated immune cells and to identify novel pathways that regulate immunosuppression. Here, we investigated the gene expression profiles of intra-tumoral immune cells isolated from NSCLC patients and compared them to the expression profiles of their counterparts in adjacent healthy tissue. Transcriptome analysis was performed on macrophages, CD4+ and CD8+ T cells. The data was subjected to Gene Ontology (GO) term enrichment and weighted correlation network analysis in order to identify mediators of immunosuppression in the tumor microenvironment in NSCLC. Immune cells from NSCLC revealed a consistent differential expression of genes involved in interactions between myeloid cells and lymphocytes. We further identified several immunosuppressive molecules and pathways that may be activated in tumor-associated macrophages in NSCLC. Importantly, we report novel data on immune cell expression of the newly described CD200/CD200R1 pathway, and the leukocyte immunoglobulin-like receptors (LILRs), which may represent novel innate immune checkpoints, dampening the anti-tumor T cell immune response in NSCLC. Our study substantiates the importance of tumor-associated macrophages as a mediator of immunosuppression and a promising target for immunotherapy.

Conversion of ATP to adenosine by CD39 and CD73 in multiple myeloma can be successfully targeted together with adenosine receptor A2A blockade

Background

PD1/PDL1-directed therapies have been unsuccessful for multiple myeloma (MM), an incurable cancer of plasma cells in the bone marrow (BM). Therefore, other immune checkpoints such as extracellular adenosine and its immunosuppressive receptor should be considered. CD39 and CD73 convert extracellular ATP to adenosine, which inhibits T-cell effector functions via the adenosine receptor A2A (A2AR). We set out to investigate whether blocking the adenosine pathway could be a therapy for MM.

Methods

Expression of CD39 and CD73 on BM cells from patients and T-cell proliferation were determined by flow cytometry and adenosine production by Liquid chromatograpy-mass spectrometry (HPCL/MS). ENTPD1 (CD39) mRNA expression was determined on myeloma cells from patients enrolled in the publicly available CoMMpass study. Transplantable 5T33MM myeloma cells were used to determine the effect of inhibiting CD39, CD73 and A2AR in mice in vivo.

Results

Elevated level of adenosine was found in BM plasma of MM patients. Myeloma cells from patients expressed CD39, and high gene expression indicated reduced survival. CD73 was found on leukocytes and stromal cells in the BM. A CD39 inhibitor, POM-1, and an anti-CD73 antibody inhibited adenosine production and reduced T-cell suppression in vitro in coculture of myeloma and stromal cells. Blocking the adenosine pathway in vivo with a combination of Sodium polyoxotungstate (POM-1), anti-CD73, and the A2AR antagonist AZD4635 activated immune cells, increased interferon gamma production, and reduced the tumor load in a murine model of MM.

Conclusions

Our data suggest that the adenosine pathway can be successfully targeted in MM and blocking this pathway could be an alternative to PD1/PDL1 inhibition for MM and other hematological cancers. Inhibitors of the adenosine pathway are available. Some are in clinical trials and they could thus reach MM patients fairly rapidly.

Bystander Memory T Cells and IMiD/Checkpoint Therapy in Multiple Myeloma: A Dangerous Tango?

In this review article we discuss the role of the memory T cells in multiple myeloma (MM) and how they may influence immune responses in patients that received immunomodulating drugs and check point therapy.

Targeting phosphoglycerate dehydrogenase in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is a hematological malignancy characterized by the clonal expansion of plasma cells in the bone marrow. To date, this disease is still incurable and novel therapeutic approaches are required. Phosphoglycerate dehydrogenase (PHGDH) is the first and rate-limiting enzyme in the de novo serine synthesis pathway, and it has been attributed to bortezomib-resistance in MM.

METHODS

Two different PHGDH inhibitors, CBR5884 and NCT-503, were tested against human myeloma cell lines, primary MM cells from patients, and peripheral blood mononuclear cells isolated from healthy donors. The PHGDH inhibitors were then tested in combination with proteasome inhibitors in different MM cell lines, including proteasome-resistant cell lines. Furthermore, we confirmed the effects of PHGDH inhibition through knocking down PHGDH and the effect of NCT-503 in vivo in the 5T33MM mouse model.

RESULTS

All the tested myeloma cell lines expressed PHGDH and were sensitive to doses of NCT-503 that were tolerated by peripheral blood mononuclear cells isolated from healthy donors. Upon testing bortezomib in combination with NCT-503, we noticed a clear synergy in several HMCLs. The sensitivity to bortezomib also increased after PHGDH knockdown, mimicking the effect of NCT-503 treatment. Interestingly, targeting PHGDH reduced the intracellular redox capacity of the cells. Furthermore, combination treatment with NCT-503 and bortezomib exhibited a therapeutic advantage in vivo.

CONCLUSIONS

Our study shows the therapeutic potential of targeting PHGDH in MM, and suggest it as a way to overcome the resistance to proteasome inhibitors.

Protein tyrosine phosphatases in multiple myeloma

Many cell signaling pathways are activated or deactivated by protein tyrosine phosphorylation and dephosphorylation, catalyzed by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), respectively. Even though PTPs are as important as PTKs in this process, their role has been neglected for a long time. Multiple myeloma (MM) is a cancer of plasma cells, which is characterized by production of monoclonal immunoglobulin, anemia and destruction of bone. MM is still incurable with high relapse frequency after treatment. In this review, we highlight the PTPs that were previously described in MM or have a role that can be relevant in a myeloma context. Our purpose is to show that despite the importance of PTPs in MM pathogenesis, many unanswered questions in this field need to be addressed. This might help to detect novel treatment strategies for MM patients.

Ectonucleotidase CD39 and Checkpoint Signalling Receptor Programmed Death 1 are Highly Elevated in Intratumoral Immune Cells in Non-small-cell Lung Cancer

Lung cancer is the leading cause of cancer death in both sexes worldwide and has a predicted 5-year survival rate of <20%. Immunotherapy targeting immune checkpoints such as the programmed death 1 (PD-1) signaling pathway has led to a shift of paradigm in the treatment of advanced non–small-cell lung cancer (NSCLC) but remains without effect in ∼80% of patients. Accumulating evidence suggests that several immunosuppressive mechanisms may work together in NSCLC. The contribution and cooperation between different immunosuppressive mechanisms in NSCLC remain unknown. Recently, the CD39-adenosine pathway has gained increasing attention as a crucial immunosuppressive mechanism and possible target for immunotherapy. Immune cells were extracted from lung and tumor tissue after lung resection in 12 patients by combined enzymatic and mechanical tissue disaggregation. A multiparameter flow cytometry panel was established to investigate the expression and coexpression of CD39 and PD-1 on key lymphocyte subtypes. Frequencies of CD39⁺, PD-1⁺, and CD39⁺/PD-1⁺cells were higher among both CD4⁺ and CD8⁺ T cells isolated from NSCLC tumor tissue than in T cells from normal lung tissue. Similarly, the frequency of FoxP3⁺ CD4⁺ T cells (Tregs) was highly significantly elevated in tumor tissue compared to adjacent lung tissue. The consistent upregulation of CD39 on immune cells in tumor microenvironment indicates that the CD39 signaling pathway may, in addition to the PD-1 pathway, represent another important mechanism for tumor-induced immunosuppression in NSCLC. In addition, the present study indicates that a comprehensive immune response profiling with flow cytometry may be both feasible and clinically relevant.

Correction: MYC amplifications in myeloma cell lines: correlation with MYC-inhibitor efficacy

[This corrects the article DOI: 10.18632/oncotarget.4245.].

PD1 is expressed on exhausted T cells as well as virus specific memory CD8+ T cells in the bone marrow of myeloma patients

Characterization of CD8+ T cells in the tumor microenvironment (TME) is important to predict responses to checkpoint therapy. The TME in multiple myeloma is the bone marrow, which also is an immune organ where immune responses are generated and memory cells stored. The presence of T cells with other specificities than the tumor in the bone marrow may affect the search for biomarkers to predict responses to immunotherapy in myeloma. Here, we found similar proportions of PD1+ CD8+ T cells and similar levels of PD1 expression on CD8+ T cells in the bone marrow of myeloma patients and healthy controls. PD1 expression on CD8+ T cells did not correlate with tumor load suggesting that at least some of the PD1+ CD8+ T cells were specific for non-myeloma antigens. Indeed, PD1+ EBV-specific CD8+ T cells were detected it the bone marrow of patients. Terminal effectors (Teff), effector memory (Tem) and central memory (Tcm) cells as well as exhausted T cells were all found in the myeloma bone marrow. However, myeloma patients had more terminal effectors and fewer memory cells than healthy controls suggesting that the tumor generate an immune response against myeloma cells in the bone marrow. The presence of CD8 EOMES^high Tbet^low T cells with intermediate levels of PD1 in myeloma patients suggests that T cell types, that are known to be responsive to checkpoint therapy, are found at the tumor site.

Abstract LB-117: Role of ectoenzymes CD39 and CD73 in the immune response to multiple myeloma

Multiple Myeloma is a cancer of the plasma cells in the bone marrow. Despite from the fact that new drugs have increased survival in the past decade, it is still an incurable cancer. It is therefore important to develop new drugs. Tumor immunosurveillance contributes to the control of cancer growth, but there many different escape mechanisms utilized by tumour to evade anti-tumour immune responses. One of the largely unexplored mechanisms of immune suppression in multiple myeloma is the role of adenosine in the bone marrow microenvironment, which now represents an attractive new therapeutic target for cancer therapy. 2 ectoenzymes, CD39 and CD73 are important for converting extracellular ATP to adenosine. When investigating the role of adenosine in the immune response to multiple myeloma, we found increased concentration of adenosine in the bone marrow plasma from myeloma patients compared with healthy controls. CD39 (ENTPD1) was expressed by myeloma cell lines and on myeloma cells from patients. CD73 was found on leukocytes and stromal cells in the bone marrow. Although very few cells expressed CD73 in the bone marrow, these cells could clearly convert AMP to adenosine. ATP was converted to AMP by CD39+ myeloma cell lines, and CD73+ stromal cells converted AMP to adenosine. Importantly, co-culture of CD39+ myeloma cells and CD73+ stromal cells catalyzed extracellular ATP to immunosuppressive adenosine. Indeed, we found that CD3 T cells stimulated with anti CD3/CD28 beads in the presence of supernatants from co-cultured cells did not proliferate as well as T cell culture without this supernatant. The fact that this proliferation was inhibited by the ZM241385 inhibitor, suggested that the suppression was mediated by the A2AR receptor. The CD39 inhibitor POM1 inhibited adenosine generation in the co-culture system as well as T cell proliferation in vitro. We have recently obtained the CD73 antibody MEDI199447 from MedImmune and are testing the ability of this antibody to prevent adenosine production and T cell proliferation in vitro, as well as the ability to reduce tumor growth in a mouse model of multiple myeloma. The clinical importance of the adenosine pathway in multiple myeloma found when analyzing patient data. Using the publicly available coMMpass database, we found that patients with high expression of CD39 had significantly reduced progression free and overall survival.

Citation Format: Rui Yang, Samah Elsaadi, Kristine Misund, Geir Slupphaug, Eline Menu, Carl Hay, Zac Cooper, Karin Vanderkerken, Magne Børset, Anne Marit Sponaas. Role of ectoenzymes CD39 and CD73 in the immune response to multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-117.

Phosphatase of regenerating liver-3 (PRL-3) is overexpressed in classical Hodgkin lymphoma and promotes survival and migration

Background

Phosphatase of regenerating liver-3 (PRL-3) is implicated in oncogenesis of hematological and solid cancers. PRL-3 expression increases metastatic potential, invasiveness and is associated with poor prognosis. With this study, we aimed to show a possible oncogenic role of PRL-3 in classical Hodgkin lymphoma (cHL).

Methods

PRL-3 expression was measured in 25 cHL patients by immunohistochemistry and gene expression was analyzed from microdissected malignant cells. We knocked down PRL-3 in the cHL cell lines L1236 and HDLM2 and used small molecular inhibitors against PRL-3 to investigate proliferation, migration and cytokine production.

Results

PRL-3 protein was expressed in 16% of patient samples. In three different gene expression datasets, PRL-3 was significantly overexpressed compared to normal controls. PRL-3 knockdown reduced proliferation, viability and Mcl-1 expression in L1236, but not in HDLM2 cells. Thienopyridone, a small molecule inhibitor of PRL-3, reduced proliferation of both L1236 and HDLM2. PRL-3 affected IL-13 secretion and enhanced STAT6 signaling. IL-13 stimulation partially rescued proliferation in L1236 cells after knockdown of PRL-3. PRL-3 knockdown reduced migration in both L1236 and HDLM2 cells.

Conclusion

PRL-3 was overexpressed in a subset of cHL patients. Inhibition of PRL-3 increased IL-13 cytokine production and reduced migration, proliferation and viability. The effects could be mediated through regulation of the anti-apoptotic molecule Mcl-1 and a feedback loop of IL-13 mediated activation of STAT6. This point to a role for PRL-3 in the pathogenesis of Hodgkin lymphoma, and PRL-3 could be a possible new drug target.

Electronic supplementary material

The online version of this article (10.1186/s40164-018-0100-2) contains supplementary material, which is available to authorized users.

Raised Serum Levels of Syndecan-1 (CD138), in a Case of Acute Idiopathic Systemic Capillary Leak Syndrome (SCLS) (Clarkson's Disease)

Patient: Female, 49

Final Diagnosis: Systemic capillary leak syndrome (SCLS)

Symptoms: Hypotension

Medication: —

Clinical Procedure: None

Specialty: Allergology

Phosphatase of regenerating liver-3 is expressed in acute lymphoblastic leukemia and mediates leukemic cell adhesion, migration and drug resistance

Phosphatase of regenerating liver-3 (PRL-3/PTP4A3) is upregulated in multiple cancers, including BCR-ABL1- and ETV6-RUNX-positive acute lymphoblastic leukemia (ALL). With this study, we aim to characterize the biological role of PRL-3 in B cell ALL (B-ALL). Here, we demonstrate that PRL-3 expression at mRNA and protein level was higher in B-ALL cells than in normal cells, as measured by qRT-PCR or flow cytometry. Further, we demonstrate that inhibition of PRL-3 using shRNA or a small molecular inhibitor reduced cell migration towards an SDF-1α gradient in the preB-ALL cell lines Reh and MHH-CALL-4. Knockdown of PRL-3 also reduced cell adhesion towards fibronectin in Reh cells. Mechanistically, PRL-3 mediated SDF-1α stimulated calcium release, and activated focal adhesion kinase (FAK) and Src, important effectors of migration and adhesion. Finally, PRL-3 expression made Reh cells more resistance to cytarabine treatment. In conclusion, the expression level of PRL-3 was higher in B-ALL cells than in normal cells. PRL-3 promoted adhesion, migration and resistance to cytarabine. PRL-3 may represent a novel target in the treatment of B-ALL.

The phosphatase of regenerating liver-3 (PRL-3) is important for IL-6-mediated survival of myeloma cells

Multiple myeloma (MM) is a neoplastic proliferation of bone marrow plasma cells. PRL-3 is a phosphatase induced by interleukin (IL)-6 and other growth factors in MM cells and promotes MM-cell migration. PRL-3 has also been identified as a marker gene for a subgroup of patients with MM. In this study we found that forced expression of PRL-3 in the MM cell line INA-6 led to increased survival of cells that were depleted of IL-6. It also caused redistribution of cells in cell cycle, with an increased number of cells in G2M-phase. Furthermore, forced PRL-3 expression significantly increased phosphorylation of Signal transducer and activator of transcription (STAT) 3 both in the presence and the absence of IL-6. Knockdown of PRL-3 with shRNA reduced survival in MM cell line INA-6. A pharmacological inhibitor of PRL-3 reduced survival in the MM cell lines INA-6, ANBL-6, IH-1, OH-2 and RPMI8226. The inhibitor also reduced survival in 9 of 9 consecutive samples of purified primary myeloma cells. Treatment with the inhibitor down-regulated the anti-apoptotic protein Mcl-1 and led to activation of the intrinsic apoptotic pathway. Inhibition of PRL-3 also reduced IL-6-induced phosphorylation of STAT3. In conclusion, our study shows that PRL-3 is an important mediator of growth factor signaling in MM cells and hence possibly a good target for treatment of MM.

Expression of phosphatase of regenerating liver (PRL)-3, is independently associated with biochemical failure, clinical failure and death in prostate cancer

Background

Prostate cancer (PC) stratification needs new prognostic tools to reduce overtreatment. Phosphatase of regenerating liver (PRL-3) is a phosphatase found at high levels in several cancer types, where its expression is associated with survival. A recent PC cell line study has shown it to be involved in PC growth and migration.

Methods

We used a monoclonal antibody to evaluate the expression of PRL-3 in PC tissue of patients in an unselected cohort of 535 prostatectomy patients. We analyzed associations between PRL-3 expression and biochemical failure-free survival (BFFS), clinical failure-free survival (CFFS) and PC death-free survival (PCDFS).

Results

Cytoplasmic PRL-3 staining in tumor cells was significantly correlated to expression of molecules in the VEGFR-axis, but not to the clinicopathological variables. High PRL-3 was not significantly associated with survival in the univariate analysis for BFFS (p = 0.131), but significantly associated with CFFS (p = 0.044) and PCDFS (p = 0.041). In multivariate analysis for the various end points, PRL-3 came out as an independent and significant indicator of poor survival for BFFS (HR = 1.53, CI95% 1.10–2.13, p = 0.012), CFFS (HR = 2.41, CI95% 1.17–4.98, p = 0.017) and PCDFS (HR = 3.99, CI95% 1.21–13.1, p = 0.023).

Conclusions

PRL-3 is independently associated with all PC endpoints in this study. Since high PRL-3 expression also correlates with poor prognosis in other cancers and functional studies in PC support these findings, PRL-3 emerges as a potential treatment target in PC.

Monitoring multiple myeloma by quantification of recurrent mutations in serum

Circulating tumor DNA is a promising biomarker to monitor tumor load and genome alterations. We explored the presence of circulating tumor DNA in multiple myeloma patients and its relation to disease activity during long-term follow-up. We used digital droplet polymerase chain reaction analysis to monitor recurrent mutations, mainly in mitogen activated protein kinase pathway genes NRAS, KRAS and BRAF. Mutations were identified by next-generation sequencing or polymerase chain reaction analysis of bone marrow plasma cells, and their presence analyzed in 251 archived serum samples obtained from 20 patients during a period of up to 7 years. In 17 of 18 patients, mutations identified in bone marrow during active disease were also found in a time-matched serum sample. The concentration of mutated alleles in serum correlated with the fraction in bone marrow plasma cells (r=0.507, n=34, P<0.002). There was a striking covariation between circulating mutation levels and M protein in ten out of 11 patients with sequential samples. When relapse evaluation by circulating tumor DNA and M protein could be directly compared, the circulating tumor DNA showed relapse earlier in two patients (3 and 9 months), later in one patient (4 months) and in three patients there was no difference. In three patients with transformation to aggressive disease, the concentrations of mutations in serum increased up to 400 times, an increase that was not seen for the M protein. In conclusion, circulating tumor DNA in myeloma is a multi-faceted biomarker reflecting mutated cells, total tumor mass and transformation to a more aggressive disease. Its properties are both similar and complementary to M protein.

Erythropoietin (EPO)-receptor signaling induces cell death of primary myeloma cells in vitro

Background

Multiple myeloma is an incurable complex disease characterized by clonal proliferation of malignant plasma cells in a hypoxic bone marrow environment. Hypoxia-dependent erythropoietin (EPO)-receptor (EPOR) signaling is central in various cancers, but the relevance of EPOR signaling in multiple myeloma cells has not yet been thoroughly investigated.

Methods

Myeloma cell lines and malignant plasma cells isolated from bone marrow of myeloma patients were used in this study. Transcript levels were analysed by quantitative PCR and cell surface levels of EPOR in primary cells by flow cytometry. Knockdown of EPOR by short interfering RNA was used to show specific EPOR signaling in the myeloma cell line INA-6. Flow cytometry was used to assess viability in primary cells treated with EPO in the presence and absence of neutralizing anti-EPOR antibodies. Gene expression data for total therapy 2 (TT2), total therapy 3A (TT3A) trials and APEX 039 and 040 were retrieved from NIH GEO omnibus and EBI ArrayExpress.

Results

We show that the EPOR is expressed in myeloma cell lines and in primary myeloma cells both at the mRNA and protein level. Exposure to recombinant human EPO (rhEPO) reduced viability of INA-6 myeloma cell line and of primary myeloma cells. This effect could be partially reversed by neutralizing antibodies against EPOR. In INA-6 cells and primary myeloma cells, janus kinase 2 (JAK-2) and extracellular signal regulated kinase 1 and 2 (ERK-1/2) were phosphorylated by rhEPO treatment. Knockdown of EPOR expression in INA-6 cells reduced rhEPO-induced phospo-JAK-2 and phospho-ERK-1/2. Co-cultures of primary myeloma cells with bone marrow-derived stroma cells did not protect the myeloma cells from rhEPO-induced cell death. In four different clinical trials, survival data linked to gene expression analysis indicated that high levels of EPOR mRNA were associated with better survival.

Conclusions

Our results demonstrate for the first time active EPOR signaling in malignant plasma cells. EPO-mediated EPOR signaling reduced the viability of myeloma cell lines and of malignant primary plasma cells in vitro. Our results encourage further studies to investigate the importance of EPO/EPOR in multiple myeloma progression and treatment.

Trial registration

[Trial registration number for Total Therapy (TT) 2: NCT00083551 and TT3: NCT00081939].

MYC amplifications in myeloma cell lines: correlation with MYC-inhibitor efficacy

In multiple myeloma, elevated MYC expression is related to disease initiation and progression. We found that in myeloma cell lines, MYC gene amplifications were common and correlated with MYC mRNA and protein. In primary cell samples MYC mRNA levels were also relatively high; however gene copy number alterations were uncommon. Elevated levels of MYC in primary myeloma cells have been reported to arise from complex genetic aberrations and are more common than previously thought. Thus, elevated MYC expression is achieved differently in myeloma cell lines and primary cells. Sensitivity of myeloma cell lines to the MYC inhibitor 10058-F4 correlated with MYC expression, supporting that the activity of 10058-F4 was through specific inhibition of MYC.

Abstract 196: The oncogenic role of PRL-3 in multiple myeloma through regulation of Src kinase family members

Introduction: Phosphatase of regenerating liver 3 (PRL-3) is a dual specificity phosphatase and its up-regulation in cancer cells is related to poor prognosis. We have previously described PRL-3 as a downstream target of IL-6 in multiple myeloma (MM) by demonstrating that it was upregulated in response to this cytokine. The Src kinase family (SFK) is composed of 8 members and regulates proto-oncogenic cellular pathways. As it has been reported that the SFK members Lyn, Fyn and Hck are important in signal transduction of IL-6 signals in MM cells and that Src is reported to be the major kinase regulated by PRL-3 in colon cancer, we evaluated effects of PRL-3 on activation of Fyn, Lyn, Hck and Src in MM.

Methods: By retroviral transduction in the IL-6-dependent MM cell line INA-6,we generated functional PRL-3(INA-PRL-3) overexpressing cells, and control cells expressing catalytically inactive mutant PRL-3 (C104S) or empty vector (Mock). We measured global tyrosine (Y) phosphorylation (P) by immunoblotting using (P-Y1000) antibody. We measured the expression of 4 SFK members by qRT PCR and immunoblotting. Activity of SFK members was evaluated using MILLIPLEX MAP8-plex Human SFK kit. We confirmed MILLIPLEX result for Src by immunoblotting with antibody against P-Y416 Src (activating phosphorylation site). We also measured Src activity after inhibiting PRL-3 by PRL-3 inhibitor I or shRNA. Finally, we showed the influence of PRL-3 on cell growth and cell sensitivity to two Src inhibitors (PP2 and Su6656) by using CellTiter-Glo Luminescent Cell Viability Assay.

Results: INA-PRL-3 had more global P-Y than C104S and Mock cells in the absence of IL-6 and showed a pattern of P-Y more similar to that of the parental INA-6 cells grown in the presence of IL-6. C104S and INA-PRL-3 cells showed lowest and highest activity, respectively, of Lyn and Src. Stimulation of cells with IL-6 increased active Lyn and Src but still C104S had lowest activity. We did not observe significant difference in activity of Fyn and Hck. Measuring total amount of 4 SFK members showed up-regulation of total Hck and Fyn in C104S cells in mRNA and protein level. This indicated that inactive PRL-3 in C104S cells leads to less SFK activity compared to both INA-PRL-3 and Mock cells. Increased total amount of Hck and Fyn in C104S could be the result of diminished negative feedback regulation of expression of SFK members by their active forms. INA-PRL-3 showed more P-Y416 Src also by immunoblotting and its inhibition by PRL-3 inhibitor or shRNA decreased Src activity. INA-PRL-3 had higher growth rate than both C104S and Mock cells. This difference was more prominent in the absence of IL-6 and high SFK activity in INA-PRL-3 could be one of the possible reasons for this. INA-PRL-3 also showed high sensitivity to both PP2 and Su6656.

Conclusion: Inhibition of PRL-3 and SFK members could be considered as a possible treatment for MM.

Citation Format: Pegah Abdollahi, Esten Nymoen Vandsemb, Magnus Aassved Hjort, Kristine Misund, Toril Holien, Torstein Baade Rø, Tobias Schmidt Slørdahl, Magne Børset. The oncogenic role of PRL-3 in multiple myeloma through regulation of Src kinase family members. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 196.

Abstract 198: The phosphatase PRL-3 is expressed in primary B-ALL cells and is important for adhesion and migration

Introduction: Phosphatase of regenerating liver -3 (PRL-3) is a dual specificity phosphatase, and is associated with aggressiveness and metastatic disease in a number of solid tumors. Less is known about its role in hematological cancer, but we have previously shown that PRL-3 is expressed in primary multiple myeloma (MM) cells and MM cell lines. More recently PRL-3 is shown to be expressed in acute myeloid leukemia (AML), and associated with poor prognosis. Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Despite progress in treatment and survival, treatment related toxicity is a major concern. Therefore, it is a need for new clinical markers and therapy targets to optimize the treatment. We hypothesized that PRL-3 is expressed, and have oncogenic functions in B-ALL, and can be a possible clinical marker and a novel drug target.

Methods: Primary ALL cells from peripheral blood were obtained from The Regional Biobank of Central Norway, and PRL-3 mRNA expression was measured with qRT-PCR. The PreB-ALL cell lines Reh and MHH-CALL-4 were used for further experiments. IL-7 (100 ng/mL) were used for stimulation. ShRNA against PRL-3 was used to knock down PRL-3 in Reh (shPRL-3) and for empty vector control (shMOCK) by use of lentiviral transduction. To study adhesion we used fibronectin (20 μg/mL) and stimulated with IL-7, IL-8 and IGF-1 (all 100 ng/mL) for 45 min in 37°C. Migration was studied with transwell permeable plates (pore size 3 μm) using SDF1α (75 ng/mL) as a chemoattractant. Further we examined the effect of the small molecular inhibitor PRL-3 Inhibitor I on ALL cell lines. Apoptosis and cell viability was determined by Annexin-FITC/-PI with flow cytometry, and by CellTiter-Glo® Luminescent Cell Viability assay kit, after 24-72 hours incubation with PRL-3 Inhibitor I.

Results: 89% (16 of 18) of primary B-ALL samples expressed PRL-3, and 33% (6 of 18) at high levels. Stimulation with IL-7 induced expression of PRL-3 in a dose-dependent manner in Reh and MHH-CALL-4. The knock down of PRL-3 by shRNA was 80% efficient. Reh shMOCK cells were significantly more adherent to fibronectin after stimulation with IL-7, IL-8 and IGF-1 compared to Reh shPRL3. The cells’ ability to migrate towards a SDF1α gradient were significantly reduced in Reh shPRL-3 cells compared with Reh shMOCK. PRL-3 inhibitor I also reduced the viability and induced apoptosis in Reh cell line in a dose-dependent manner, but not in MHH-CALL-4 cell line, at a concentration of 40-80 μM.

Conclusion: PRL-3 was expressed in 89% of primary B-ALL samples. Knock down of PRL-3 clearly reduced cell adhesion and migration. PRL-3 inhibitor I induced apoptosis and reduced cell viability in Reh, but not in MHH-CALL-4. This study indicates that PRL-3 could be important in the pathogenesis of B-ALL, and might be a suitable target for treatment in the future.

Citation Format: Magnus Aassved A. Hjort, Pegah Abdollahi, Esten Vandsemb, Tobias Schmidt Slørdahl, Bendik Lund, Magne Børset, Torstein Baade Rø. The phosphatase PRL-3 is expressed in primary B-ALL cells and is important for adhesion and migration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 198.

VOLIN and KJON-Two novel hyperdiploid myeloma cell lines

Multiple myeloma can be divided into two distinct genetic subgroups: hyperdiploid (HRD) or nonhyperdiploid (NHRD) myeloma. Myeloma cell lines are important tools to study myeloma cell biology and are commonly used for preclinical screening and testing of new drugs. With few exceptions human myeloma cell lines are derived from NHRD patients, even though about half of the patients have HRD myeloma. Thus, there is a need for cell lines of HRD origin to enable more representative preclinical studies. Here, we present two novel myeloma cell lines, VOLIN and KJON. Both of them were derived from patients with HRD disease and shared the same genotype as their corresponding primary tumors. The cell lines' chromosomal content, genetic aberrations, gene expression, immunophenotype as well as some of their growth characteristics are described. Neither of the cell lines was found to harbor immunoglobulin heavy chain translocations. The VOLIN cell line was established from a bone marrow aspirate and KJON from peripheral blood. We propose that these unique cell lines may be used as tools to increase our understanding of myeloma cell biology. © 2016 Wiley Periodicals, Inc.

Phosphatase of regenerating liver 3 (PRL-3) is overexpressed in human prostate cancer tissue and promotes growth and migration

Background

PRL-3 is a phosphatase implicated in oncogenesis in multiple cancers. In some cancers, notably carcinomas, PRL-3 is also associated with inferior prognosis and increased metastatic potential. In this study we investigated the expression of PRL-3 mRNA in fresh-frozen samples from patients undergoing radical prostatectomy because of prostate cancer (PC) and the biological function of PRL-3 in prostate cancer cells.

Methods

Samples from 41 radical prostatectomy specimens (168 samples in total) divided into low (Gleason score ≤ 6), intermediate (Gleason score = 7) and high (Gleason score ≥ 8) risk were analyzed with gene expression profiling and compared to normal prostate tissue. PRL-3 was identified as a gene with differential expression between healthy and cancerous tissue in these analyses. We used the prostate cancer cell lines PC3 and DU145 and a small molecular inhibitor of PRL-3 to investigate whether PRL-3 had a functional role in cancer. Relative ATP-measurement and thymidine incorporation were used to assess the effect of PRL-3 on growth of the cancer cells. We performed an in vitro scratch assay to investigate the involvement of PRL-3 in migration. Immunohistochemistry was used to identify PRL-3 protein in prostate cancer primary tumor and corresponding lymph node metastases.

Results

Compared to normal prostate tissue, the prostate cancer tissue expressed a significantly higher level of PRL-3. We found PRL-3 to be present in both PC3 and DU145, and that inhibition of PRL-3 led to growth arrest and apoptosis in these two cell lines. Inhibition of PRL-3 led to reduced migration of the PC3 cells. Immunohistochemistry showed PRL-3 expression in both primary tumor and corresponding lymph node metastases.

Conclusions

PRL-3 mRNA was expressed to a greater extent in prostate cancer tissue compared to normal prostate tissue. PRL-3 protein was expressed in both prostate cancer primary tumor and corresponding lymph node metastases. The results from our in vitro assays suggest that PRL-3 promotes growth and migration in prostate cancer. In conclusion, these results imply that PRL-3 has a role in the pathogenesis of prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0830-z) contains supplementary material, which is available to authorized users.

Allelic mutations in noncoding genomic sequences construct novel transcription factor binding sites that promote gene overexpression

The growth and survival factor hepatocyte growth factor (HGF) is expressed at high levels in multiple myeloma (MM) cells. We report here that elevated HGF transcription in MM was traced to DNA mutations in the promoter alleles of HGF. Sequence analysis revealed a previously undiscovered single-nucleotide polymorphism (SNP) and crucial single-nucleotide variants (SNVs) in the promoters of myeloma cells that produce large amounts of HGF. The allele-specific mutations functionally reassembled wild-type sequences into the motifs that affiliate with endogenous transcription factors NFKB (nuclear factor kappa-B), MZF1 (myeloid zinc finger 1), and NRF-2 (nuclear factor erythroid 2-related factor 2). In vitro, a mutant allele that gained novel NFKB-binding sites directly responded to transcriptional signaling induced by tumor necrosis factor alpha (TNFα) to promote high levels of luciferase reporter. Given the recent discovery by genome-wide sequencing (GWS) of numerous non-coding mutations in myeloma genomes, our data provide evidence that heterogeneous SNVs in the gene regulatory regions may frequently transform wild-type alleles into novel transcription factor binding properties to aberrantly interact with dysregulated transcriptional signals in MM and other cancer cells.

Activated CD8+ T cells and natural killer T cells in bronchoalveolar lavage fluid in hypersensitivity pneumonitis and sarcoidosis

BACKGROUND

Sarcoidosis and hypersensitivity pneumonitis are diffuse parenchymal lung diseases characterized by formation of non-caseating granulomas with a bronchocentric distribution. Analysis of the white blood cell differential profile in bronchoalveolar lavage fluid can be a useful supplement in the diagnostic work-up.

OBJECTIVE

Diagnostic markers that can improve the discrimination of sarcoidosis and hypersensitivity pneumonitis are wanted.

METHODS

Bronchoalveolar lavage fluid fractions of CD4+ and CD8+ T cells expressing the activation marker HLA-DR and fractions of natural killer T cells determined by flow cytometry were investigated in sarcoidosis (N=83), hypersensitivity pneumonitis (N=10) and healthy control subjects (N=15).

RESULTS

In hypersensitivity pneumonitis, natural killer T cell fractions were over 7-fold greater [median (IQR): 5.5% (3.5-8.1) versus 0.7% (0.5-1.2), p<0.0001], and HLA-DR+ fractions of CD8+ lymphocytes were almost two fold greater [median (IQR): 79% (75-82) versus 43% (34-52), p<0.0001] than in sarcoidosis. In healthy control subjects, natural killer T cell fractions of leucocytes and HLA-DR+ fractions of CD8+ lymphocytes were lower [median (IQR): 0.3% (0.3-0.6) and 30% (26-34), p=0.02 and p=0.01 compared to sarcoidosis]. The combined use of these two markers seems to discriminate the diseases very well.

CONCLUSION

This study suggests a role for the bronchoalveolar lavage fluid lymphocyte subsets HLA-DR+ CD8+ T cells and natural killer T cells in the diagnostic work up of sarcoidosis and hypersensitivity pneumonitis.

Identification of the source of elevated hepatocyte growth factor levels in multiple myeloma patients

Background

Hepatocyte growth factor (HGF) is a pleiotropic cytokine which can lead to cancer cell proliferation, migration and metastasis. In multiple myeloma (MM) patients it is an abundant component of the bone marrow. HGF levels are elevated in 50% of patients and associated with poor prognosis. Here we aim to investigate its source in myeloma.

Methods

HGF mRNA levels in bone marrow core biopsies from healthy individuals and myeloma patients were quantified by real-time PCR. HGF gene expression profiling in CD138⁺ cells isolated from bone marrow aspirates of healthy individuals and MM patients was performed by microarray analysis. HGF protein concentrations present in peripheral blood of MM patients were measured by enzyme-linked immunosorbent assay (ELISA). Cytogenetic status of CD138⁺ cells was determined by fluorescence in situ hybridization (FISH) and DNA sequencing of the HGF gene promoter. HGF secretion in co-cultures of human myeloma cell lines and bone marrow stromal cells was measured by ELISA.

Results

HGF gene expression profiling in both bone marrow core biopsies and CD138⁺ cells showed elevated HGF mRNA levels in myeloma patients. HGF mRNA levels in biopsies and in myeloma cells correlated. Quantification of HGF protein levels in serum also correlated with HGF mRNA levels in CD138⁺ cells from corresponding patients. Cytogenetic analysis showed myeloma cell clones with HGF copy numbers between 1 and 3 copies. There was no correlation between HGF copy number and HGF mRNA levels. Co-cultivation of the human myeloma cell lines ANBL-6 and JJN3 with bone marrow stromal cells or the HS-5 cell line resulted in a significant increase in secreted HGF.

Conclusions

We here show that in myeloma patients HGF is primarily produced by malignant plasma cells, and that HGF production by these cells might be supported by the bone marrow microenvironment. Considering the fact that elevated HGF serum and plasma levels predict poor prognosis, these findings are of particular importance for patients harbouring a myeloma clone which produces large amounts of HGF.

Activated CD8(+) T cells and NKT cells in BAL fluid improve diagnostic accuracy in sarcoidosis

PURPOSE

The clinical diagnosis of pulmonary sarcoidosis is based on the presence of noncaseating granulomas in an appropriate clinical setting with either bilateral hilar adenopathy and/or parenchymal infiltrates. Lymphocytosis with an increased CD4/CD8 T cell ratio in bronchoalveolar lavage fluid is supportive. We evaluated the diagnostic accuracy of a predictive binary logistic regression model in sarcoidosis based on sex, age, and bronchoalveolar lavage fluid cell profile with and without the inclusion of HLA-DR(+) CD8(+) T cells and natural killer T-cell fractions.

METHODS

A retrospective analysis of differential cell counts and lymphocyte phenotypes by flow cytometry in bronchoalveolar lavage was performed in 183 patients investigated for possible diffuse parenchymal lung disease. A logistic regression model with age, sex, lymphocyte fraction, eosinophils, and CD4/CD8 ratio in bronchoalveolar lavage fluid (basic model) was compared with a final model, which also included fractions of HLA-DR(+) CD8(+) T cells and natural killer T cells. Diagnostic accuracy of the two models was assessed by receiver operating characteristic (ROC) curves.

RESULTS

The area under the ROC curve for the basic and final model was 0.898 [95 % confidence interval (CI) 0.852-0.945] and 0.937 (95 % CI 0.902-0.972), respectively, p = 0.008.

CONCLUSIONS

Assessment of HLA-DR(+) CD8(+) T cell and natural killer T-cell fractions may improve diagnostic accuracy and further strengthen the importance of bronchoalveolar lavage in the diagnostic workup of sarcoidosis.

Anti-c-MET Nanobody - a new potential drug in multiple myeloma treatment

BACKGROUND

c-MET is the tyrosine kinase receptor of the hepatocyte growth factor (HGF). HGF-c-MET signaling is involved in many human malignancies, including multiple myeloma (MM). Recently, multiple agents have been developed directed to interfere at different levels in HGF-c-MET signaling pathway. Nanobodies are therapeutic proteins based on the smallest functional fragments of heavy-chain-only antibodies. In this study, we wanted to determine the anticancer effect of a novel anti-c-MET Nanobody in MM.

METHODS

We examined the effects of an anti-c-MET Nanobody on thymidine incorporation, migration, adhesion of MM cells, and osteoblastogenesis in vitro. Furthermore, we investigated the effects of the Nanobody on HGF-dependent c-MET signaling by Western blotting.

RESULTS

We show that the anti-c-MET Nanobody effectively inhibited thymidine incorporation of ANBL-6 MM cells via inhibition of an HGF autocrine growth loop and thymidine incorporation in INA-6 MM cells induced by exogenous HGF. HGF-induced migration and adhesion of INA-6 were completely and specifically blocked by the Nanobody. Furthermore, the Nanobody abolished the inhibiting effect of HGF on bone morphogenetic protein-2-induced alkaline phosphatase activity and the mineralization of human mesenchymal stem cells. Finally, we show that the Nanobody reduced phosphorylation of tyrosine residues in c-MET, MAPK, and Akt. We also compared the Nanobody with anti-c-MET monoclonal antibodies and revealed the similar or better effect.

CONCLUSIONS

The anti-c-MET Nanobody inhibited MM cell migration, thymidine incorporation, and adhesion, and blocked the HGF-mediated inhibition of osteoblastogenesis. The anti-c-MET Nanobody might represent a novel therapeutic agent in the treatment of MM and other cancers driven by HGF-c-MET signaling.

Decorin is down-regulated in multiple myeloma and MGUS bone marrow plasma and inhibits HGF-induced myeloma plasma cell viability and migration

OBJECTIVES

Decorin is a stromal-produced small leucine-rich proteoglycan known to attenuate tumour pro-survival, migration, proliferation and angiogenic signalling pathways. Recent studies have shown that decorin interacts with the hepatocyte growth factor (HGF) receptor c-Met, a potential key pathway in multiple myeloma (MM).

METHODS

Decorin levels in paired peripheral blood and bone marrow plasma samples from healthy volunteers (HV) (n = 23), and patients with monoclonal gammopathy of undetermined significance (MGUS) (n = 41) and MM (n = 19) were determined by ELISA. Further, the ability of decorin to inhibit HGF-induced effects on MM cell lines were analysed in vitro using cell viability and Transwell migration assays.

RESULTS

We found that decorin concentrations were significantly higher (P < 0.05) in bone marrow (BM) plasma from HVs (median 35.2 ng/mL; range, 15.3-99.1) compared with MGUS (median 22.5 ng/mL; range, 11.1-59.5) and patients with MM (median 21.5 ng/mL; range, 10.6-35.9). Decorin levels were higher in BM plasma than in peripheral blood in all groups, with a BM/PB ratio of 3.9, 3.4 and 2.5 for HV, MGUS and MM, respectively. A positive correlation (Spearman's ρ = 0.51, P < 0.05) was found between simultaneously measured levels of HGF and decorin in BM plasma in HVs, but not in MGUS or MM samples. Functionally, decorin inhibited HGF-induced migration and viability of INA-6 and ANBL-6 MM cell lines, independent of c-Met down-regulation.

CONCLUSION

Our results show that decorin is down-regulated in MGUS and MM bone marrow plasma and that it inhibits HGF-induced viability and migration of myeloma cell lines in vitro.

Abstract 5624: Anti-c-Met Nanobody®: A potential new drug in cancer treatment

c-Met is the tyrosine kinase receptor of the hepatocyte growth factor (HGF). HGF-c-Met signaling is involved in a wide variety of human malignancies including colon, gastric, bladder, breast, ovarian, pancreatic, kidney, liver, lung, head and neck, thyroid, and prostate cancers, as well as sarcomas, hematological malignancies, melanoma and central nervous system tumors. In recent years, multiple agents have been developed directed to interfere at different levels in the HGF-c-Met signaling pathway, and some are currently being tested in Phase II and/or III clinical trials.

Nanobodies® are therapeutic proteins based on the smallest functional fragments of heavy chain antibodies, occurring in the Camelidae family. Importantly, they retain the full antigen-binding capacity of the original heavy chain only antibodies and are highly stable. In this study, we examined the anti-cancer effects of an anti-c-Met Nanobody in vitro using human multiple myeloma as a model system. The anti-c-Met Nanobody comprises of two Nanobody moieties, one targeting c-Met and one binding to human serum albumin for half-life extension. HGF is thought to contribute to the pathogenesis of multiple myeloma in different ways, as HGF is a pivotal growth and pro-migratory factor and inhibits osteoblastogenesis in vitro suggesting that HGF may contribute to the development of myeloma bone disease. Elevated levels of HGF in serum of multiple myeloma patients are correlated with a poor prognosis.

We show that the anti-c-Met Nanobody effectively inhibited the proliferation of ANBL-6 human multiple myeloma cells via inhibition of an HGF autocrine growth loop, as well as the proliferation of INA-6 cells induced by exogenously added HGF. In addition, the HGF-induced migration of INA-6 cells was completely and specifically blocked following treatment with the Nanobody at a concentration of 1 μM. The Nanobody also inhibited the HGF-induced adhesion of multiple myeloma cells to fibronectin, but did not affect stromal cell-derived factor-1 alpha-induced adhesion. Furthermore, the Nanobody abolished the inhibiting effect of HGF on bone morphogenetic protein-2-induced ALP-activity and the mineralization of human mesenchymal stem cells. Finally, we show that the Nanobody reduced the HGF mediated phosphorylation of the c-Met Tyrosine (Y) residues Y1349, Y1234/1235 and Y1003 and the phosphorylation of the downstream proteins MAPK and Akt in INA-6 cells.

In conclusion, the anti-c-Met Nanobody inhibited c-Met signaling with high specificity and potency resulting in inhibition of multiple myeloma cell migration, proliferation and adhesion, and in blocking of the HGF mediated inhibition of osteoblastogenesis. Given the potential of Nanobodies to surpass drawbacks of antibodies, this anti-c-Met Nanobody might represent a potential novel therapeutic agent in the treatment of multiple myeloma and other cancers driven by HGF-c-Met signaling.

Citation Format: Tobias S. Slørdahl, Tinneke Denayer, Siv Helen Moen, Therese Standal, Magne Børset, Cedric Ververken, Torstein B. Rø. Anti-c-Met Nanobody®: A potential new drug in cancer treatment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5624. doi:10.1158/1538-7445.AM2013-5624

HGF and IGF-1 synergize with SDF-1α in promoting migration of myeloma cells by cooperative activation of p21-activated kinase

Stromal-derived factor (SDF)-1α, insulin-like growth factor (IGF)-1 and hepatocyte growth factor (HGF) are potent mediators of cell migration. We studied the effect of combinations of these cytokines on the migration of myeloma cells. When SDF-1α was combined with either HGF or IGF-1, we found a striking synergy in the cytokines' ability to guide cells across a transwell membrane. Between HGF and IGF-1 there was no cooperativity. However, the effects of HGF and IGF-1 were not redundant. HGF and SDF-1 caused concentration gradient-directed migration, as opposed to IGF-1, which apparently caused randomly directed cell movement. The SDF-1α-driven migration of JJN-3 cells, a myeloma cell line secreting large amounts of HGF, was reduced when JJN-3 cells were given an inhibitor of the HGF receptor, demonstrating a cooperative activity between autocrine HGF and exogenous SDF-1α. There was a clear positive correlation between the degree of cytokine-induced migration and phosphorylation of p21-activated kinase (PAK) both in primary myeloma cells and in cell lines including INA-6 and IH-1. Downregulation of PAK with small interfering RNA in INA-6 cells resulted in decreased cytokine-driven migration. This study shows synergy between SDF-1α and HGF/IGF-1 in inducing migration of myeloma cells, yet each cytokine has distinct properties in the way it regulates cell migration. These findings are likely to be of clinical relevance because multiple myeloma cells are located in an environment containing HGF and IGF-1 and are exposed to an SDF-1α gradient between the bone marrow and peripheral blood.

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

Bone morphogenetic proteins induce apoptosis in multiple myeloma cells by Smad-dependent repression of MYC

Bone morphogenetic proteins (BMPs) have been shown to induce apoptosis and growth arrest in myeloma cells. However, the molecular mechanisms behind these events are not known. The MYC oncogene is a master regulator of cell growth and protein synthesis and MYC overexpression has been proposed to be associated with the progression of multiple myeloma. Here, we show that BMP-induced apoptosis in myeloma cells is dependent on downregulation of MYC. Moreover, the results suggest that targeting the MYC addiction in multiple myeloma is an efficient way of killing a majority of primary myeloma clones. We also found that myeloma cells harboring immunoglobulin (IG)-MYC translocations evaded BMP-induced apoptosis, suggesting a novel way for myeloma cells to overcome potential tumor suppression by BMPs.

Soluble c-Met in serum of patients with multiple myeloma: correlation with clinical parameters

OBJECTIVES

The receptor tyrosine kinase c-Met and its ligand, hepatocyte growth factor (HGF), play key roles in tumour genesis and metastasis and contribute in multiple myeloma pathogenesis. Substantial data support that a soluble extracellular fragment of c-Met may function as a decoy receptor that downregulates the biological effects of HGF and c-Met. We examined serum levels of soluble c-Met in patients with myeloma and healthy individuals and investigated a possible relationship with clinical disease parameters and survival.

METHODS

The concentration of c-Met and HGF was measured by enzyme-linked immunosorbent assay in serum (n=49) and bone marrow plasma (n=16) from patients with multiple myeloma and in serum from healthy controls (n=26).

RESULTS

The median serum concentration of soluble c-Met was 186 ng/mL (range 22-562) in patients with multiple myeloma and 189 ng/mL (range 124-397) in healthy individuals. There was a significant negative correlation between serum c-Met levels and disease stage, bone marrow plasma cell percentage and serum concentration of M-protein.

CONCLUSION

We have for the first time examined the concentration of soluble c-Met in serum from patients with myeloma and found equal median levels in patients with myeloma as a group and healthy individuals. Still, serum levels of soluble c-Met correlated negatively with parameters of disease burden in patients with myeloma. We suggest that a possible role for the c-Met ectodomain as a negative regulator of HGF/c-Met activity should be examined in multiple myeloma.

Serglycin inhibits the classical and lectin pathways of complement via its glycosaminoglycan chains: implications for multiple myeloma

Serglycin (SG) is a proteoglycan expressed by hematopoietic cells and is constitutively secreted by multiple myeloma (MM) cells. SG participates in the regulation of various inflammatory events. We found that SG secreted by human MM cell lines inhibits both the classical and lectin pathways of complement, without influencing alternative pathway activity. The inhibitory effect of SG is due to direct interactions with C1q and mannose-binding lectin (MBL). C1q-binding is mediated through the glycosaminoglycan moieties of SG, whereas MBL binds additionally to SG protein core. Interactions between SG and C1q as well as MBL are diminished in the presence of chondroitin sulfate type E. In addition, we localized the SG-binding site to the collagen-like stalk of C1q. Interactions between SG and C1q as well as MBL are ionic in character and only the interaction with MBL was found to be partially dependent on the presence of calcium. We found the serum levels of SG to be elevated in patients with MM compared to healthy controls. Moreover, we found that SG expressed from myeloma plasma cells protects these cells from complement activation induced by treatment with anti-thymocyte immunoglobulins. This might protect myeloma cells during immunotherapy and promote survival of malignant cells.

FGFR3 is expressed and is important for survival in INA-6, a human myeloma cell line without a t(4;14)

OBJECTIVES

Fibroblast growth factor receptor 3 (FGFR3) is a proto-oncogene that is often dysregulated together with multiple myeloma SET-domain (MMSET) by the immunoglobulin heavy chain (IGH) gene in t(4;14)(pos) multiple myeloma (MM) cells, and which is usually not expressed in MM cells without this translocation. Whether FGFR3 may play a role in MM cells without t(4;14) and the IGH-MMSET fusion protein is unclear and is the focus of this report.

METHODS

FGFR3 expression was explored in cell lines with and without t(4;14) by fluorescence in situ hybridization (FISH), RT-PCR and Western Blot. FGFR3 inhibitors SU5402 and PD173074 were used to explore the role of FGFR3 in these cells.

RESULTS

We discovered an amplification of the FGFR3 locus in INA-6, a human MM cell line. We also demonstrated expression of FGFR3 mRNA and protein in the cells, probably caused by the extra copy of the gene. INA-6 cells did not have t(4;14) and neither was there any involvement of the other IG loci in translocations with the FGFR3 gene. The FGFR3 inhibitors decreased the proliferation of INA-6.

CONCLUSION

The decreased viability and proliferation in INA-6, following inhibition with FGFR3 inhibitors, indicates that FGFR3 may play a role also in cells without t(4;14) - and hence without high expression of MMSET, the ubiquitous oncoprotein in MM cells with t(4;14). This gives further credibility to the notion that FGFR3 expression is not just an epiphenomenon in t(4;14) MM, but an important part of the malignant phenotype.

OH-2, a hyperdiploid myeloma cell line without an IGH translocation, has a complex translocation juxtaposing MYC near MAFB and the IGK locus

Multiple myeloma can be classified into hyperdiploid (HRD) (with 48-74 chromosomes) and non-hyperdiploid tumors (usually with immunoglobulin heavy chain translocations). The OH-2 human myeloma cell line (HMCL) retains the same HRD genotype as the primary tumor, with extra copies of chromosomes 3, 7, 15, 19, and 21. Both OH-2 and primary cells have a complex secondary translocation in which the IGK 3' enhancer is inserted between MYC and MAFB, resulting in dysregulation of both oncogenes. OH-2 provides a unique example of an HMCL and the corresponding primary tumor that are shown to share the same HRD genotype.

High expression of BCL3 in human myeloma cells is associated with increased proliferation and inferior prognosis

BACKGROUND

BCL3 is a putative oncogene encoding for a protein belonging to the inhibitory kappaB-family. We experienced that this putative oncogene was a common target gene for growth-promoting cytokines in myeloma cell lines.

METHODS

Gene expression of BCL3 was studied in 351 newly diagnosed myeloma patients, 12 patients with smouldering myeloma, 44 patients with monoclonal gammopathy of undetermined significance and 22 healthy individuals. Smaller material of samples was included for mRNA detection by RT-PCR, protein detection by Western blot and immunohistochemistry, and for cytogenetic studies. A total of eight different myeloma cell lines were studied.

RESULTS

Bcl-3 was induced in myeloma cell lines by interleukin (IL)-6, IL-21, IL-15, tumor necrosis factor-alpha and IGF-1, and its upregulation was associated with increased proliferation of the cells. In a population of 351 patients, expression levels of BCL3 above 75th percentile were associated with shorter 5-yr survival. When this patient population was divided into subgroups based on molecular classification, BCL3 was significantly increased in a poor risk subgroup characterized by overexpression of cell cycle and proliferation related genes. Intracellular localization of Bcl-3 was dependent on type of stimulus given to the cell.

CONCLUSION

BCL3 is a common target gene for several growth-promoting cytokines in myeloma cells and high expression of BCL3 at the time of diagnosis is associated with poor prognosis of patients with multiple myeloma (MM). These data may indicate a potential oncogenic role for Bcl-3 in MM.

c-Met signaling promotes IL-6-induced myeloma cell proliferation

Objectives:

Hepatocyte growth factor (HGF) is a constituent of the myeloma microenvironment and is elevated in sera from myeloma patients compared to healthy individuals. Increased levels of serum HGF predict a poor prognosis. It has previously been shown by us and others HGF can act as a growth factor to myeloma cells in vitro although these effects have been moderate. We therefore wanted to investigate if HGF could influence the effects of interleukin (IL)-6.

Methods:

Myeloma cell lines and primary samples were tested for the combined effects of IL-6 and HGF in inducing DNA synthesis and migration. Expression levels of c-Met protein were analysed by Western blotting and flow cytometry. Signaling pathways were examined by Western blotting using phosphospecific antibodies and a Ras-GTP pull down assay.

Results:

HGF potentiated IL-6-induced growth in human myeloma cell lines and in purified primary myeloma cells. There was also cooperation between HGF and IL-6 in induction of migration. There seemed to be two explanations for this synergy. IL-6-treatment increased the expression of c-Met making cells HGF responsive, and IL-6 was dependent on c-Met signaling in activating both Ras and p44/42 MAPK by a mechanism involving the tyrosine phosphatase Shp2.

Conclusions:

The results indicate that besides from being a myeloma growth factor alone, HGF can also potentiate the effects of IL-6 in myeloma proliferation and migration. Thus, c-Met signaling could be a target for therapy of multiple myeloma.

Elevated serum concentrations of activated hepatocyte growth factor activator in patients with multiple myeloma

OBJECTIVES

Hepatocyte growth factor (HGF) is a potential key factor in multiple myeloma. Conversion of pro-HGF to its active form is a critical limiting step for its biological effects. We aimed to examine the levels of the most potent activator, the hepatocyte growth factor activator (HGFA), in serum and bone marrow plasma of patients with multiple myeloma.

METHODS

The activated form of HGFA was measured by an enzyme-linked immunosorbent assay in serum (n = 49) and bone marrow plasma (n = 16) from multiple myeloma patients, and in serum from healthy controls (n = 24).

RESULTS

The median concentrations of activated HGFA in myeloma and control sera were 39.7 (range 6.2-450.0) and 17.6 ng/mL (range 4.8-280.6), respectively. The difference was statistically significant (P = 0.037). The median concentration of activated HGFA in bone marrow plasma was 6.1 ng/mL (range 3.5-30.0).

CONCLUSION

We here show for the first time that the activated form of HGFA is present at high levels in serum and bone marrow of myeloma patients, thus providing a necessary prerequisite for the activation of HGF.