Molecular aspects of multiple myeloma

The Impact of Modern Bone Markers in Multiple Myeloma: Prospective Analyses Pre and Post-First Line Treatment

Multiple myeloma, the disease characterized by the malignant proliferation of plasma cells that invades the bone marrow, produces osteolytic lesions and secretes monoclonal proteins. Several biomarkers have been shown to represent important tools in the pathogenesis of myeloma and offer insights into bone degradation and formation. The objectives of this current study were to assess the associations of modern biomarkers (TNF-α: tumor necrosis factor; IFN: Interferon; FreeRANKL: Free Receptor Activator for Nuclear Factor kappa B Ligand; RANKL: Receptor Activator for Nuclear Factor kappa B Ligand, Beta crosslaps, IL-6: Interleukin 6) with osteolytic lesions status after first-line treatment and to evaluate the correlations between modern and classical biomarkers (LDH: Lactate Dehydrogenase; VSH: Erythrocyte Sedimentation Rate; Hgb: Hemoglobin, Calcium, Albumin, B2microglobulin) stratified by osteolytic lesions status. A total of 35 patients diagnosed with multiple myeloma divided into two groups according to the osteolytic bone lesions, were studied: (1) unchanged status of osteolytic lesions and (2) changed status of osteolytic lesions. After fist-line treatment, we found a significant difference in Albumin (p = 0.0029) and Calcium levels (p = 0.0304), patients with a changed status in osteolytic lesions having higher values of Albumin and Calcium compared to those without changes in status of osteolytic lesions. After first-line treatment, decreased IL-6 values were significantly correlated with elevated values of Albumin (ρ = -0.96, p = 0.0005) in the patients with changed status of osteolytic lesions. Post-treatment values of IFN showed a significant positive correlation with Hemoglobin (ρ = 0.47, p = 0.0124), IL-6 (ρ = 0.55, p = 0.0026) and TNF-alpha values (ρ = 0.54, p = 0.0029). The results obtained from patients with unmodified lytic lesions identified a significant correlation between the biomarkers IL-6, Free RANKL, and IFN-beta with the classical marker LDH. This association highlights the involvement of these markers in promoting bone destruction and the development of osteolytic lesions.

The JAK1/2 inhibitor ruxolitinib downregulates the immune checkpoint protein B7H3 in multiple myeloma

We hypothesized that ruxolitinib may inhibit the immune checkpoint protein, B7H3; and, thus, investigated its effects on this immune inhibitor using multiple myeloma (MM) cell lines, bone marrow (BM) mononuclear cells from MM patients and human MM LAGλ -1A xenografts. Ruxolitinib reduced B7H3 gene and protein expression and increased IL-2 and CD8 gene expression. These results suggest that ruxolitinib inhibition of B7H3 may restore exhausted T-cell activity in the MM BM tumor microenvironment.

A phase 1 study of ruxolitinib, steroids and lenalidomide for relapsed/refractory multiple myeloma patients

Ruxolitinib with lenalidomide and dexamethasone shows anti-myeloma effects in vitro and in vivo. MUC1 leads to lenalidomide resistance in multiple myeloma (MM) cells, and ruxolitinib blocks its expression. Thus, ruxolitinib may restore sensitivity to lenalidomide. A phase I trial was conducted to determine the safety and efficacy of ruxolitinib with lenalidomide and methylprednisolone for patients with relapsed/refractory (RR)MM who had been treated with lenalidomide, steroids and a proteasome inhibitor and showed progressive disease at study entry. A traditional 3 + 3 dose escalation design was used to enroll subjects in four cohorts. Subjects received ruxolitinib twice daily, lenalidomide daily on days 1-21 of a 28 day cycle and methylprednisolone orally every other day. Primary endpoints were safety, clinical benefit rate (CBR) and overall response rate (ORR). Forty-nine patients were enrolled. The median age was 64 years and they had received a median of six prior treatments including lenalidomide and steroids to which 94% were refractory. No dose limiting toxicities occurred. The CBR and ORR were 49% and 36%, respectively. All responding patients were refractory to lenalidomide. Grade 3 or 4 adverse events (AEs) included anemia (17%), decreased lymphocyte count (15%), and hypophosphatemia (10%). Most common serious AEs included sepsis (9.8%) and pneumonia (7.8%). This Phase I trial demonstrates that a JAK inhibitor, ruxolitinib, can overcome refractoriness to lenalidomide and steroids for patients with RRMM. These results represent a promising novel therapeutic approach for treating MM. NCT03110822.

Baseline and Changes in Serum B-Cell Maturation Antigen Levels Rapidly Indicate Changes in Clinical Status Among Patients with Relapsed/Refractory Multiple Myeloma Starting New Therapy

BACKGROUND

B-cell maturation antigen (BCMA) is expressed on malignant plasma cells from patients with multiple myeloma (MM). These patients have higher levels of serum (s)BCMA than healthy subjects, and levels correlate with disease status. The half-life of sBCMA is only 24-36 h, and levels are independent of renal function.

OBJECTIVE

We determined whether baseline sBCMA values, a ≥ 25% increase, and a ≥ 50% decrease during treatment predicted progression-free survival (PFS) and overall survival (OS) among 81 patients with relapsed/refractory MM (RRMM) starting new treatments.

METHODS

Serum was obtained on day 22 of each patient's 28-day cycle of new therapy. Kaplan-Meier survival analysis and log-rank comparison tests were used to determine the effect of baseline sBCMA. The effect of percentage change in sBCMA was investigated using time-dependent Cox proportional hazard models.

RESULTS

Patients with baseline sBCMA levels above the median had a shorter PFS (p = 0.0077), and those in the highest quartile had a shorter PFS (p = 0.0012) and OS (p = 0.0022). A ≥ 25% increase at week 4, week 8, and anytime through week 12 predicted a shorter PFS (p = 0.0011, p = 0.0005, and p < 0.0001, respectively). A ≥ 50% decrease at week 4, week 8, and anytime through week 12 predicted a longer PFS (p = 0.0045, p = 0.029, p = 0.0055, respectively). A ≥ 25% increase in sBCMA occurred before progression according to International Myeloma Working Group criteria in 67.5% of patients.

CONCLUSIONS

Our results indicate the potential for the use of sBCMA as a new biomarker for monitoring patients with RRMM.

Application of Immune Infiltration Signature and Machine Learning Model in the Differential Diagnosis and Prognosis of Bone-Related Malignancies

Bone-related malignancies, such as osteosarcoma, Ewing's sarcoma, multiple myeloma, and cancer bone metastases have similar histological context, but they are distinct in origin and biological behavior. We hypothesize that a distinct immune infiltrative microenvironment exists in these four most common malignant bone-associated tumors and can be used for tumor diagnosis and patient prognosis. After sample cleaning, data integration, and batch effect removal, we used 22 publicly available datasets to draw out the tumor immune microenvironment using the ssGSEA algorithm. The diagnostic model was developed using the random forest. Further statistical analysis of the immune microenvironment and clinical data of patients with osteosarcoma and Ewing's sarcoma was carried out. The results suggested significant differences in the microenvironment of bone-related tumors, and the diagnostic accuracy of the model was higher than 97%. Also, high infiltration of multiple immune cells in Ewing's sarcoma was suggestive of poor patient prognosis. Meanwhile, increased infiltration of macrophages and B cells suggested a better prognosis for patients with osteosarcoma, and effector memory CD8 T cells and type 2 T helper cells correlated with patients' chemotherapy responsiveness and tumor metastasis. Our study revealed that the random forest diagnostic model based on immune infiltration can accurately perform the differential diagnosis of bone-related malignancies. The immune microenvironment of osteosarcoma and Ewing's sarcoma has an important impact on patient prognosis. Suppressing the highly inflammatory environment of Ewing's sarcoma and promoting macrophage and B cell infiltration may have good potential to be a novel adjuvant treatment option for osteosarcoma and Ewing's sarcoma.

Anti-VEGF Drugs in the Treatment of Multiple Myeloma Patients

The interaction between the bone marrow microenvironment and plasma cells plays an essential role in multiple myeloma progression and drug resistance. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway in vascular endothelial cells activates and promotes angiogenesis. Moreover, VEGF activates and promotes vasculogenesis and vasculogenic mimicry when it interacts with VEGF receptors expressed in precursor cells and inflammatory cells, respectively. In myeloma bone marrow, VEGF and VEGF receptor expression are upregulated and hyperactive in the stromal and tumor cells. It has been demonstrated that several antiangiogenic agents can effectively target VEGF-related pathways in the preclinical phase. However, they are not successful in treating multiple myeloma, probably due to the vicarious action of other cytokines and signaling pathways. Thus, the simultaneous blocking of multiple cytokine pathways, including the VEGF/VEGFR pathway, may represent a valid strategy to treat multiple myeloma. This review aims to summarize recent advances in understanding the role of the VEGF/VEGFR pathway in multiple myeloma, and mainly focuses on the transcription pathway and on strategies that target this pathway.

A Phase I Study of Ruxolitinib, Lenalidomide, and Steroids for Patients with Relapsed/Refractory Multiple Myeloma

PURPOSE

Ruxolitinib with lenalidomide and dexamethasone shows antimyeloma effects in vitro and in vivo. MUC1 leads to lenalidomide resistance in multiple myeloma cells, and ruxolitinib blocks its expression. Thus, ruxolitinib may restore sensitivity to lenalidomide. Therefore, a phase I trial was conducted to determine the safety and efficacy of ruxolitinib with lenalidomide and methylprednisolone for patients with relapsed/refractory multiple myeloma (RRMM) who had been treated with lenalidomide/steroids and a proteasome inhibitor and showed progressive disease at study entry.

PATIENTS AND METHODS

A traditional 3+3 dose escalation design was used to enroll subjects in four cohorts with planned total enrollment of 28 patients. Subjects received ruxolitinib twice daily, lenalidomide daily on days 1-21 of a 28-day cycle, and methylprednisolone orally every other day. Primary endpoints were safety, clinical benefit rate (CBR), and overall response rate (ORR).

RESULTS

Twenty-eight patients were enrolled. The median age was 67 years and received a median of six prior treatments including lenalidomide and steroids to which 93% were refractory. No dose-limiting toxicities occurred. The CBR and ORR were 46% and 38%, respectively. All 12 responding patients were refractory to lenalidomide. Grade 3 or grade 4 adverse events (AE) included anemia (18%), thrombocytopenia (14%), and lymphopenia (14%). Most common serious AEs included sepsis (11%) and pneumonia (11%).

CONCLUSIONS

This phase I trial demonstrates that a JAK inhibitor, ruxolitinib, can overcome refractoriness to lenalidomide and steroids for patients with RRMM. These results represent a promising novel therapeutic approach for treating multiple myeloma (ClinicalTrials.gov number, NCT03110822).

Anti-myeloma Effects of Icariin Are Mediated Through the Attenuation of JAK/STAT3-Dependent Signaling Cascade

Because of the essential role of signal transducer and activator of transcription 3 (STAT3) in proliferation, anti-apoptosis, and chemoresistance of multiple myeloma (MM), we investigated whether icariin, a prenylated flavonol glycoside, inhibits both constitutive and inducible STAT3 activation in human myeloma cell lines. We noted that icariin could block constitutive STAT3 phosphorylation as well as its nuclear translocation and DNA binding ability in U266 cells. Icariin also suppressed IL-6-induced STAT3 activation through the inhibition of upstream kinases (Janus activated kinase-1 and -2, and c-Src). We found that icariin downregulated the protein expression of STAT3 downstream target gene products such as Bcl-2, Bcl-xl, survivin, IAP-1/2, COX-2, VEGF, and matrix metallopeptidase 9 (MMP-9) in a concentration-dependent manner. Moreover, this flavonoid also exhibited the capacity to significantly induce apoptosis and suppress proliferation of MM cells. Interestingly, this agent also significantly potentiated the apoptotic effects of bortezomib through the suppression of STAT3 activation in MM cells. Altogether, our data indicates that the potential application of icariin as a STAT3 blocker in myeloma therapy.

Evaluation of in vitro effects of various targeted drugs on plasma cells and putative neoplastic stem cells in patients with multiple myeloma

Multiple myeloma (MM) is a malignancy characterized by monoclonal paraproteinemia and tissue plasmocytosis. In advanced MM cytopenia and osteopathy may occur. Although several effective treatment strategies have been developed in recent years, there is still a need to identify new drug targets and to develop more effective therapies for patients with advanced MM. We examined the effects of 15 targeted drugs on growth and survival of primary MM cells and 5 MM cell lines (MM.1S, NCI-H929, OPM-2, RPMI-8226, U-266). The PI3-kinase blocker BEZ235, the pan-BCL-2 inhibitor obatoclax, the Hsp90-targeting drug 17AAG, and the Polo-like kinase-1 inhibitor BI2536, were found to exert major growth-inhibitory effects in all 5 MM cell lines tested. Moreover, these drugs suppressed the in vitro proliferation of primary bone marrow-derived MM cells and induced apoptosis at pharmacologic drug concentrations. Apoptosis-inducing effects were not only seen in the bulk of MM cells but also in MM stem cell-containing CD138⁻/CD20⁺/CD27⁺ memory B-cell fractions. Synergistic growth-inhibitory effects were observed in MM cell lines using various drug combinations, including 17AAG+BI2536 in MM.1S, OPM-2, RPMI-8226, and U-266 cells, 17AAG+BEZ235 in MM.1S, OPM-2, RPMI-8226, and U-266 cells, 17AAG+obatoclax in MM.1S, NCI-H929, OPM-2, and RPMI-8226 cells, BI2536+BEZ235 in MM.1S, NCI-H929, OPM-2, and RPMI-8226 cells, BI2536+obatoclax in MM.1S, OPM-2 and RPMI-8226 cells, and BEZ235+obatoclax in MM.1S and RPMI-8226 cells. Together, our data show that various targeted drugs induce profound and often synergistic anti-neoplastic effects in MM cells which may have clinical implications and may contribute to the development of novel treatment strategies in advanced MM.

Using Genome Sequence to Enable the Design of Medicines and Chemical Probes

Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.

Serum B-cell maturation antigen: a novel biomarker to predict outcomes for multiple myeloma patients

B-cell maturation antigen is expressed on plasma cells. In this study, we have identified serum B-cell maturation antigen as a novel biomarker that can monitor and predict outcomes for multiple myeloma patients. Compared to healthy donors, patients with multiple myeloma showed elevated serum B-cell maturation antigen levels (P<0.0001). Serum B-cell maturation antigen levels correlated with the proportion of plasma cells in bone marrow biopsies (Spearman's rho = 0.710; P<0.001), clinical status (complete response vs partial response, P=0.0374; complete response vs progressive disease, P<0.0001), and tracked with changes in M-protein levels. Among patients with non-secretory disease, serum B-cell maturation antigen levels correlated with bone marrow plasma cell levels and findings from positron emission tomography scans. Kaplan-Meier analysis demonstrated that serum B-cell maturation antigen levels above the median levels were predictive of a shorter progression-free survival (P=0.0006) and overall survival (P=0.0108) among multiple myeloma patients (n=243). Specifically, patients with serum B-cell maturation antigen levels above the median level at the time of starting front-line (P=0.0043) or a new salvage therapy (P=0.0044) were found to have shorter progression-free survival. Importantly, serum B-cell maturation antigen levels did not show any dependence on renal function and maintained independent significance when tested against other known prognostic markers for multiple myeloma such as age, serum β2 microglobulin, hemoglobin, and bone disease. These data identify serum B-cell maturation antigen as a new biomarker to manage multiple myeloma patients.

Ectopic microRNA-150-5p transcription sensitizes glucocorticoid therapy response in MM1S multiple myeloma cells but fails to overcome hormone therapy resistance in MM1R cells

Glucocorticoids (GCs) selectively trigger cell death in the multiple myeloma cell line MM1S which express NR3C1/Glucocorticoid Receptor (GR) protein, but fail to kill MM1R cells which lack GR protein. Given recent demonstrations of altered microRNA profiles in a diverse range of haematological malignancies and drug resistance, we characterized GC inducible mRNA and microRNA transcription profiles in GC sensitive MM1S as compared to GC resistant MM1R cells. Transcriptome analysis revealed that GCs regulate expression of multiple genes involved in cell cycle control, cell organization, cell death and immunological disease in MM1S cells, which remain unaffected in MM1R cells. With respect to microRNAs, mir-150-5p was identified as the most time persistent GC regulated microRNA, out of 5 QPCR validated microRNAs (mir-26b, mir-125a-5p, mir-146-5p, mir-150-5p, and mir-184), which are GC inducible in MM1S but not in MM1R cells. Functional studies further revealed that ectopic transfection of a synthetic mir-150-5p mimics GR dependent gene expression changes involved in cell death and cell proliferation pathways. Remarkably, despite the gene expression changes observed, overexpression of mir-150-5p in absence of GCs did not trigger significant cytotoxicity in MM1S or MM1R cells. This suggests the requirement of additional steps in GC induced cell death, which can not be mimicked by mir-150-5p overexpression alone. Interestingly, a combination of mir-150-5p transfection with low doses GC in MM1S cells was found to sensitize therapy response, whereas opposite effects could be observed with a mir-150-5p specific antagomir. Although mir-150-5p overexpression did not substantially change GR expression levels, it was found that mir-150-5p evokes GR specific effects through indirect mRNA regulation of GR interacting transcription factors and hormone receptors, GR chaperones, as well as various effectors of unfolded protein stress and chemokine signalling. Altogether GC-inducible mir-150-5p adds another level of regulation to GC specific therapeutic responses in multiple myeloma.

Extracavitary primary effusion lymphoma presenting as a cutaneous tumor: a case report and literature review

Primary effusion lymphoma is an unusual form of aggressive B-cell lymphoma universally associated with human herpesvirus 8 (HHV8) that involves mostly human immunodeficiency virus (HIV)-infected patients. Characteristically, it presents as a malignant serous effusion involving body cavities, but without associated tumor mass. Exceptionally, HHV8-positive lymphomas with features identical to primary effusion lymphoma may present as mass lesions in the absence of cavity effusions along the course of the disease, and are regarded as extracavitary or solid variants of the disorder. These rare forms are extremely rare in the skin. We report a case of extracavitary primary effusion lymphoma arising in a HIV-infected male, who presented with two subcutaneous masses involving the skin of the abdominal and inguinal regions as the first manifestation of the process. Kaposi sarcoma was not present in the skin surface or mucous membranes. Extensive studies failed to demonstrate involvement of other organs and the case was considered as an example of extracavitary primary effusion lymphoma originating primarily in the skin. Herein, we review the few reported cases of solid primary effusion lymphoma involving the skin in order to delineate the clinicopathologic, immunohistochemical and molecular characteristics of this rare lymphoma in the skin.

Neoplastic plasma cell aberrant antigen expression patterns and their association with genetic abnormalities

Little is known about aberrant antigen expression patterns and their association with cytogenetic aberrations in multiple myeloma (MM). We examined the correlation between flow cytometry and florescence in situ hybridization (FISH) in 167 marrow specimens with MM. Gene expression profiling of CD56, CD117, CD52 and CD20 mRNA in plasma cells (PCs) from patients treated on Total Therapy 2 and Total Therapy 3 trials were also evaluated. Higher expression of CD56 and CD117 was associated with hyperdiploidy. High CD52 mRNA expression was associated with c-MAF and FGFR3 subgroups. Higher expression of CD56 mRNA, but lower Kit expression, were noted in association with FGFR3. In contrast, the c-MAF subgroup showed high Kit expression but lacked NCAM mRNA expression. CKS1B amplification showed positive correlation with CD52 (p=0.0065) but negative correlation with CD20 (p=0.0207). These findings indicate that phenotypic differences in MM are associated with distinct genetic subgroups, which potentially has important diagnostic and prognostic value.

CD38 ligation in peripheral blood mononuclear cells of myeloma patients induces release of protumorigenic IL-6 and impaired secretion of IFNγ cytokines and proliferation

CD38, a surface receptor that controls signals in immunocompetent cells, is densely expressed by cells of multiple myeloma (MM). The immune system of MM patients appears as functionally impaired, with qualitative and quantitative defects in T cell immune responses. This work answers the issue whether CD38 plays a role in the impairment of T lymphocyte response. To this aim, we analyzed the signals implemented by monoclonal antibodies (mAb) ligation in peripheral blood mononuclear cells (PBMC) obtained from MM patients and compared to benign monoclonal gammopathy of undetermined significance (MGUS). PBMC from MM both failed to proliferate and secrete IFNγ induced by CD38 ligation while it retained the ability to respond to TCR/CD3. The impaired CD38-dependent proliferative response likely reflects an arrest in the progression of cell cycle, as indicated by the reduced expression of PCNA. CD38 signaling showed an enhanced ability to induce IL-6 secretion. PBMC from MM patients displays a deregulated response possibly due to defects of CD38 activation pathways and CD38 may be functionally involved in the progression of this pathology via the secretion of high levels of IL-6 that protects neoplastic cells from apoptosis.

Arsenic trioxide inhibits the proliferation of myeloma cell line through notch signaling pathway

Arsenic Trioxide (ATO) has shown remarkable efficacy for the treatment of multiple myeloma (MM). However, the mechanism by which ATO exerts its inhibitory effect on the proliferation of myeloma cells remains to be clarified. We study the inhibitory effect of ATO at various concentrations on the proliferation of the myeloma cell line RPMI 8226 and discussed the molecular mechanism of ATO on myeloma cell line. Our results proved that ATO had a significant dose-dependent and time-dependent inhibitory effect on the expressions of the Notch receptor (Notch1) and Notch ligand (Jag2). Data from the real-time PCR assay showed that the mRNA expression levels of the Jag2 gene and its downstream gene Hes1 were both significantly down-regulated after the myeloma cells were treated with ATO while the expression of the tumor suppressor gene PTEN was up-regulated. These results elucidated the molecular mechanism underlying the ATO mediated inhibition of myeloma cell proliferation. This is the first report on the anti-myeloma activity in myeloma cells through inhibition of the Notch signaling pathway.

Multiple myeloma macrophages: pivotal players in the tumor microenvironment

Tumor microenvironment is essential for multiple myeloma (MM) growth, progression, and drug resistance through provision of survival signals and secretion of growth and proangiogenic factors. This paper examines the importance of macrophages within MM bone marrow (BM) microenvironment, referred to as MM-associated macrophages, as a potential niche component that supports tumor plasma cells. These macrophages are derived from peripheral blood monocytes recruited into the tumor. Upon activation by MM plasma cells and mesenchymal stromal cells, macrophages can release growth factors, proteolytic enzymes, cytokines, and inflammatory mediators that promote plasma cell growth and survival. Macrophages promote tumor progression through several mechanisms including angiogenesis, growth, and drug resistance. Indeed, these macrophages are essential for the induction of an angiogenic response through vasculogenic mimicry, and this ability proceeds in step with progression of the plasma cell tumors. Data suggest that macrophages play an important role in the biology and survival of patients with MM, and they may be a target for the MM antivascular management.

Macrophages and mesenchymal stromal cells support survival and proliferation of multiple myeloma cells

Multiple myeloma (MM) is characterized by almost exclusive tropism of malignant cells for the bone marrow (BM) milieu. The survival and proliferation of malignant plasma cells have been shown to rely on interactions with nonmalignant stromal cells, in particular mesenchymal stromal cells (MSCs), in the BM microenvironment. However, the BM microenvironment is composed of a diverse array of cell types. This study examined the role of macrophages, an abundant component of BM stroma, as a potential niche component that supports malignant plasma cells. We investigated the proliferation of MM tumour cell lines when cultured alone or together with MSCs, macrophages, or a combination of MSCs and macrophages, using the carboxyfluorescein succinimidyl ester assay. Consistently, we observed increased proliferation of MM cell lines in the presence of either MSCs or macrophages compared to cell line-only control. Furthermore, the combined co-culture of MSCs plus macrophages induced the greatest degree of proliferation of myeloma cells. In addition to increased proliferation, MSCs and macrophages decreased the rate of apoptosis of myeloma cells. Our in vitro studies provide evidence that highlights the role of macrophages as a key component of the BM microenvironment facilitating the growth of malignant plasma cells in MM.

Constitutive NF-kappaB activation confers interleukin 6 (IL6) independence and resistance to dexamethasone and Janus kinase inhibitor INCB018424 in murine plasmacytoma cells

Myeloma cells are dependent on IL6 for their survival and proliferation during the early stages of disease, and independence from IL6 is associated with disease progression. The role of the NF-κB pathway in the IL6-independent growth of myeloma cells has not been studied. Because human herpesvirus 8-encoded K13 selectively activates the NF-κB pathway, we have used it as a molecular tool to examine the ability of the NF-κB pathway to confer IL6 independence on murine plasmacytomas. We demonstrated that ectopic expression of K13, but not its NF-κB-defective mutant or a structural homolog, protected plasmacytomas against IL6 withdrawal-induced apoptosis and resulted in emergence of IL6-independent clones that could proliferate long-term in vitro in the absence of IL6 and form abdominal plasmacytomas with visceral involvement when injected intraperitoneally into syngeneic mice. These IL6-independent clones were dependent on NF-κB activity for their survival and proliferation but were resistant to dexamethasone and INCB018424, a selective Janus kinase 1/2 inhibitor. Ectopic expression of human T cell leukemia virus 1-encoded Tax protein, which resembles K13 in inducing constitutive NF-κB activation, similarly protected plasmacytoma cells against IL6 withdrawal-induced apoptosis. Although K13 is known to up-regulate IL6 gene expression, its protective effect was not due to induction of endogenous IL6 production but instead was associated with sustained expression of several antiapoptotic members of the Bcl2 family upon IL6 withdrawal. Collectively, these results demonstrate that NF-κB activation cannot only promote the emergence of IL6 independence during myeloma progression but can also confer resistance to dexamethasone and INCB018424.

MicroRNAs: New Players in Multiple Myeloma

MicroRNAs (miRNAs) are short non-coding RNAs that play critical roles in numerous cellular processes through post-transcriptional regulating functions. The aberrant role of miRNAs has been reported in a number of hematopoietic malignancies including multiple myeloma (MM). In this review we summarize the current knowledge on roles of miRNAs in the pathogenesis of MM.

Oncolytic virotherapy for multiple myeloma: past, present, and future

Multiple myeloma (MM) is a B-cell malignancy that is currently felt to be incurable. Despite recently approved novel targeted treatments such as lenalidomide and bortezomib, most MM patients' relapse is emphasizing the need for effective and well-tolerated therapies for this deadly disease. The use of oncolytic viruses has garnered significant interest as cancer therapeutics in recent years, and are currently under intense clinical investigation. Both naturally occurring and engineered DNA and RNA viruses have been investigated preclinically as treatment modalities for several solid and hematological malignancies. Presently, only a genetically modified measles virus is in human clinical trials for MM. The information obtained from this and other future clinical trials will guide clinical application of oncolytic viruses as anticancer agents for MM. This paper provides a timely overview of the history of oncolytic viruses for the treatment of MM and future strategies for the optimization of viral therapy for this disease.

Variation in innate immunity genes and risk of multiple myeloma

Multiple myeloma (MM) is a B-cell lymphoid malignancy suspected to be associated with immunologic factors. Given recent findings associating single-nucleotide polymorphisms (SNPs) in innate immunity genes with non-Hodgkin lymphoma, we conducted an investigation of innate immune gene variants using specimens from a population-based case-control study of MM conducted in Connecticut women. Tag SNPs (N = 1461) summarizing common variation in 149 gene regions were genotyped in non-Hispanic Caucasian subjects (103 cases, 475 controls). Odds ratios (OR) and 95% confidence intervals (CI) relating SNP associations with MM were computed using unconditional logistic regression, while the MinP test was used to investigate associations with MM at the gene level. We calculated permutation-adjusted P-values and false discovery rates (FDR) to account for the number of comparisons performed in SNP-level and gene-level tests, respectively. Three genes were associated with MM when controlling for a FDR of ≤10%: SERPINE1 (P(MinP)  < 0.0001; FDR = 0.02), CCR7 (P(MinP)  = 0.0006; FDR = 0.06) and HGF (P(MinP)  = 0.001; FDR = 0.08). Two SNPs demonstrated robust associations: SERPINE1 rs2227667 (P = 2.1 × 10(-5) , P(permutation)  = 0.03) and HGF rs17501108 (P = 5.0 × 10(-5) , P(permutation)  = 0.07). Our findings suggest that genetic variants in SERPINE1 and HGF, and possibly CCR7, are associated with MM risk, and warrant further investigation in other studies.

DNA methylation alterations in multiple myeloma as a model for epigenetic changes in cancer

Epigenetics refers to heritable modifications of the genome that are not a result of changes in the DNA sequence and result in phenotypic changes. These changes can be stably transmitted through cell division and are potentially reversible. Epigenetic events are very important during normal development wherein a single progenitor cell proliferates and differentiates into various somatic cell types. This process occurs through modification of the genome without changing the genetic code. Because epigenetic control of gene expression is so important, aberrant epigenetic regulation can lead to disease and cancer. This article reviews epigenetic changes seen in cancer by examining epigenetic changes commonly found in multiple myeloma, a common hematologic malignancy of plasma cells. Epigenetic control of gene expression can be exerted by changes in DNA methylation, histone modifications, and expression of noncoding RNAs. Each of these regulatory mechanisms interacts with the others at different genomic locations and can be measured quantitatively within the cell, requiring that we consider these mechanisms not individually but as a biological system. DNA methylation was the earliest discovered epigenetic regulator and has been the focus of most investigations in cancer. We have thus focused on DNA methylation changes in the pathogenesis of multiple myeloma, which promises to become an excellent model for systems biological studies of epigenomic dysregulation in human disease.

Tumour formation by single fibroblast growth factor receptor 3-positive rhabdomyosarcoma-initiating cells

Background:

The hypothesis that malignant tumours are generated by rare populations of cancer stem cells that are more tumourigenic than other cancer cells has gained increasing credence. The objective of this study was to identify and characterise a subpopulation of human sarcoma-initiating cells.

Methods:

We examined established rhabdomyosarcoma cell lines by flow cytometry. Tumourigenesis was examined by xenograft models. Real-time PCR and immunohistochemistry were performed to examine the gene expression using cell lines and biopsy specimens.

Results:

Rhabdomyosarcoma cell lines included small populations of fibroblast growth factor receptor 3 (FGFR3)-positive cells. FGFR3-positive KYM-1 and RD cells were more strongly tumourigenic than FGFR3-negative cells. In addition, xenoengraftment of 33% of single FGFR3-positive KYM-1 cells yielded tumour formation. Stem cell properties of FGFR3-positive cells were further established by real-time PCR, which demonstrated upregulation of undifferentiated cell markers and downregulation of differentiation markers. We showed that in the absence of serum, addition of basic fibroblast growth factor maintained and enriched FGFR3-positive cells. On the other hand, ciliary neurotrophic factor reduced the proportion of FGFR3-positive cells. Real-time PCR and immunohistochemical examination revealed that embryonal rhabdomyosarcoma patient biopsy specimens were found to over-express FGFR3.

Conclusions:

Our findings suggest that rhabdomyosarcoma cell lines include a minor subpopulation of FGFR3-positive sarcoma-initiating cells, which can be maintained indefinitely in culture and which is crucial for their malignancy.

TGFbetaR2 aberrant methylation is a potential prognostic marker and therapeutic target in multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy. Different studies demonstrated the occurrence of genetic and epigenetic alterations in MM. The aberrant methylation is one of the most frequent epigenetic alterations in human genome. This study evaluated the aberrant methylation status of 20 genes in 51 MM samples by quantitative methylation-specific PCR (QMSP) and compared the methylation profile with clinicopathological characteristics of the patients. The QMSP analyses showed that PTGS2 (100.0%), SFN (100.0%), CDKN2B (90.2%), CDH1 (88.2%), ESR1 (72.5%), HIC1 (70.5%), CCND2 (62.7%), DCC (45.1%) and TGFbetaR2 (39.2%) are frequently hypermethylated in MM while aberrant methylation of RARbeta (16.6%), MGMT (12.5%), AIM1 (12.5%), CDKN2A (8.3%), SOCS1 (8.3%), CCNA1 (8.3%) and THBS1 (4.1%) are rare events. There was no methylation of GSTP1, MINT31, p14ARF and RB1 in the samples tested. Hypermethylation of ESR1 was correlated positively with isotype IgA, while aberrant methylation of THBS1 correlated negatively with isotype IgG. Furthermore, hypermethylation of DCC and TGFbetaR2 were correlated with poor survival. The multivariate analysis showed ISS and TGFbetaR2 hypermethylation strongly correlated with poor outcome. This study represents the first quantitative evaluation of promoter methylation in MM and our data provide evidence that TGFbetaR2 hypermethylation, besides ISS, may be useful as prognostic indicator in this disease.

In-vitro functional phenotypes of plasma cell lines from patients with multiple myeloma

Seven plasma cell lines from patients with smoldering (group A) and overt myeloma (group B) were investigated for both phenotypic markers and in-vitro properties, including sensitivity to apoptosis, cytotoxicity, cell adhesion, chemotaxis and bone interaction. Cell lines from group A underwent apoptosis whereas those from group B were apparently resistant, promoted cytotoxicity in target cells and enhanced both adhesion and migratory functions upon appropriate activators. In addition, MCC-2, a group B cell line from a patient with severe osteolytic disease of the skeleton produced erosive lacunae on bone substrates, whereas this effect was almost absent with cell lines from group A. Concurrent deregulation of relative markers, in combination with peculiar properties including resistance to apoptosis and high cytotoxic potential, as well as adhesion, chemotaxis and bone pathophysiology interactions, may thus identify myeloma cells with aggressive phenotype driving these biological activities in vitro and perhaps in vivo.

Differential repetitive DNA methylation in multiple myeloma molecular subgroups

Multiple myeloma (MM) is characterized by a wide spectrum of genetic changes. Global hypomethylation of repetitive genomic sequences such as long interspersed nuclear element 1 (LINE-1), Alu and satellite alpha (SAT-alpha) sequences has been associated with chromosomal instability in cancer. Methylation status of repetitive elements in MM has never been investigated. In the present study, we used a quantitative bisulfite-polymerase chain reaction pyrosequencing method to evaluate the methylation patterns of LINE-1, Alu and SAT-alpha in 23 human myeloma cell lines (HMCLs) and purified bone marrow plasma cells from 53 newly diagnosed MM patients representative of different molecular subtypes, 7 plasma cell leukemias (PCLs) and 11 healthy controls. MMs showed a decrease of Alu [median: 21.1 %5-methylated cytosine (%5mC)], LINE-1 (70.0%5mC) and SAT-alpha (77.9%5mC) methylation levels compared with controls (25.2, 79.5and 89.5%5mC, respectively). Methylation levels were lower in PCLs and HMCLs compared with MMs (16.7 and 14.8%5mC for Alu, 45.5 and 42.4%5mC for LINE-1 and 33.3 and 43.3%5mC for SAT-alpha, respectively). Notably, LINE-1 and SAT-alpha methylation was significantly lower in the non-hyperdiploid versus hyperdiploid MMs (P = 0.01 and 0.02, respectively), whereas Alu and SAT-alpha methylation was significantly lower in MMs with t(4;14) (P = 0.02 and 0.004, respectively). Finally, we correlated methylation patterns with DNA methyltransferases (DNMTs) messenger RNA levels showing in particular a progressive and significant increase of DNMT1 expression from controls to MMs, PCLs and HMCLs (P < 0.001). Our results indicate that global hypomethylation of repetitive elements is significantly associated with tumor progression in MM and may contribute toward a more extensive stratification of the disease.

New targets and treatments in multiple myeloma: Src family kinases as central regulators of disease progression

Multiple myeloma is a malignant condition that most commonly occurs in the seventh decade of life. Recent improvements in treatment may result in a more favourable outlook for recently diagnosed patients. Multiple myeloma is an incurable clonal B-cell malignancy, which is initially responsive to conventional chemotherapy; one-third of the patients achieve complete remission but multidrug resistance eventually develops. Although autologous stem cell transplantation remains an important option, many older patients are less tolerant to the toxicity associated with conditioning treatment, as well as being intrinsically less likely to do well after transplantation. Most patients eventually relapse with or without transplantation, and salvage therapy is only moderately effective. Thalidomide and subsequently, lenalidomide and bortezomib, have demonstrated improved outcomes for these patients, as well as proving efficacious in front-line regimens. A deeper understanding of the molecular mechanisms underlying multiple myeloma has given rise to novel targeted approaches. This review will focus in particular on Src-dependent signalling pathways, reflecting the expanding realisation of the critical and ubiquitous role of Src family kinases (SFKs) in normal and abnormal hematopoiesis.

Phenylhexyl isothiocyanate has dual function as histone deacetylase inhibitor and hypomethylating agent and can inhibit myeloma cell growth by targeting critical pathways

Histone deacetylase (HDAC) inhibitors are a new class of chemotherapeutic agents. Our laboratory has recently reported that phenylhexyl isothiocyanate (PHI), a synthetic isothiocyanate, is an inhibitor of HDAC. In this study we examined whether PHI is a hypomethylating agent and its effects on myeloma cells. RPMI8226, a myeloma cell line, was treated with PHI. PHI inhibited the proliferation of the myeloma cells and induced apoptosis in a concentration as low as 0.5 μM. Cell proliferation was reduced to 50% of control with PHI concentration of 0.5 μM. Cell cycle analysis revealed that PHI caused G1-phase arrest of RPMI8226 cells. PHI induced p16 hypomethylation in a concentration- dependent manner. PHI was further shown to induce histone H3 hyperacetylation in a concentration-dependent manner. It was also demonstrated that PHI inhibited IL-6 receptor expression and VEGF production in the RPMI8226 cells, and reactivated p21 expression. It was found that PHI induced apoptosis through disruption of mitochondrial membrane potential. For the first time we show that PHI can induce both p16 hypomethylation and histone H3 hyperacetylation. We conclude that PHI has dual epigenetic effects on p16 hypomethylation and histone hyperacetylation in myeloma cells and targets several critical processes of myeloma proliferation.

Common variants in genes that mediate immunity and risk of multiple myeloma

Multiple myeloma (MM) is a B-cell malignancy characterized by aberrant immune function. Using genomic DNA extracted from 127 MM cases aged 21-84 years and 545 population-based controls, we examined the risk of MM associated with 82 common variants in 45 genes that mediate immunity among women of European American descent. Genotyping was determined using validated and optimized TaqMan assays. We estimated haplotype frequencies from unphased genotype data for 20 of these genes using the expectation-maximization progressive insertion algorithm. Compared with controls, MM risk was positively associated with homozygotes of single loci, IL4R (-28120T, rs2107356) and FCGR2A (-120G, rs1801274) (OR = 1.91, 95% CI 1.08-3.38 and 1.95, 95% CI 1.06-3.60, respectively). For genes in which linkage disequilibrium was observed between multiple loci, MM risk was positively associated with the haplotype block covering part of the LTA*TNF complex (LTA -82C/-90G *TNF -1036C/-487G/-417G, OR = 1.63, 95% CI 1.02-2.16) compared with the most frequently occurring haplotype observed among controls (LTA -82A/-90A *TNF -1036C/-487G/-417G). Our findings provide preliminary evidence that common genetic variants in specific immune-mediated pathways could influence the risk of MM.

The immunomodulator AS101 induces growth arrest and apoptosis in Multiple Myeloma: Association with the Akt/Survivin pathway

Multiple Myeloma (MM) is a clonal B-cell malignancy affecting both the immune and the skeletal systems, and accounts for 10% of all hematological cancers. The immunomodulator ammonium trichloro (dioxoethylene-O,O') tellurate (AS101) is a non-toxic compound which has direct anti-tumoral properties in several tumor models. The present study examined the anti-tumoral activity of AS101 in MM by targeting the Akt/Survivin signaling pathway, crucial for survival. We showed that AS101 inhibites cell proliferation and colonies formation of MM cell lines, in a dose-dependent manner. AS101 induced G(2)/M growth arrest and increased both cyclin-dependent kinase inhibitor p21(waf1) protein levels and Cdk1 (p34(cdc2))-inhibitory phosphorylation. Longer incubation of MM cells with AS101 resulted in accumulation of apoptotic cell population and in increased caspase 9, 3 and 7 activities. We also showed that AS101 down-regulated Akt phosphorylation and decreased expression of the inhibitor of apoptosis, survivin. Since Akt and survivin are potentials targets for MM therapy, we suggest that AS101, currently being used in clinical studies, may have therapeutic implications in myeloma and other hematopoietic malignancies.

Inhibitors of the mevalonate pathway as potential therapeutic agents in multiple myeloma

Clinical studies have suggested that bisphosphonates may prolong the survival of sub-sets of myeloma patients. Newer nitrogen containing bisphosphonates such as zoledronate act, at least in part, by inhibiting farnesyl diphosphate synthase and subsequent protein prenylation, furthermore, limited data suggests that zoledronate exerts a direct anti-tumour effect against human myeloma cell lines. We therefore investigated the anti-myeloma potential of zoledronate in comparison to, and in combination with, two other inhibitors of the mevalonate pathway: the HMGCoA reductase inhibitor fluvastatin and the farnesyl transferase inhibitor SCH66336. We found that fluvastatin was able to inhibit the proliferation of myeloma cells more effectively than zoledronate or SCH66336 and that combinations of zoledronate and fluvastatin, but not zoledronate and SCH66336 acted synergistically. Our data indicated that the anti-proliferative effect of mevalonate pathway inhibitors is mediated principally via prevention of geranylgeranylation and is the result of both cell cycle arrest and apoptosis induction. Microarray and quantitative real-time PCR analyses further demonstrated that genes related to apoptosis, cell cycle control, and the mevalonate pathway were particularly affected by zoledronate and fluvastatin, and that some of these genetic effects were synergistic. We conclude that the mechanisms of geranylgeranylation inhibition mediated anti-myeloma effects warrant further evaluation and may provide novel targets for future therapeutic development.

The role of nuclear factor κB on angiogenesis regulation through monocyte chemotactic protein-1 in myeloma

Multiple myeloma is malignant proliferation of plasma cells and plasmacytoid cells. Vascular endothelial growth factor (VEGF) is known to be one of the most important if not the main regulator of physiologic and pathologic angiogenesis which triggers growth, survival and migration of myeloma cells. It has been shown that circulating mature or bone marrow driven endothelial precursor cells play an important role in neovascularisation. In accordance with these observations, current therapeutic approaches to myeloma include VEGF inhibitors. Since angiogenesis inhibitors are heterogeneous in origin and potency, and their growing list includes many products with a different function it would be of benefit to determine the key molecule produced by transformed plasma cells which stimulates bone marrow environment to produce their homing "milieu" secreting different cytokines such as VEGF, IL-6, and monocyte chemotactic protein-1 (MCP-1). This molecule could be nuclear factor kappa B (NF-kappaB). It has been confirmed that myeloma cells express and produce NF-kappaB. It has been established recently that by blocking NF-kappaB production MCP-1 secretion is reduced up to 60%. If so, this would also reduce production of IL-6 and VEGF, since MCP-1 upregulates VEGF and IL-6 production. This way one could make bone marrow bad environment for myeloma cells to settle, followed with no disease progression. Targeting to NF-kappaB intended to inhibits its activation with receptor antagonist would possibly significantly inhibit lipopolysaccharide-induced IL-6, MCP-1 and TNF-alpha. All of them being stimulators for VEGF secretion and indirectly activation of angiogenesis. To conclude, angiogenesis could be induced by myeloma cells themselves through NF-kappaB activation pathway and by inhibiting its activation we might prevent myeloma expansion in bone marrow and progression of the disease by decreased MCP-1 secretion.

Combining prenylation inhibitors causes synergistic cytotoxicity, apoptosis and disruption of RAS-to-MAP kinase signalling in multiple myeloma cells

The high incidence of activating RAS mutations, coupled with accumulating evidence linking RAS to multiple myeloma (MM) pathogenesis, indicate that novel therapies utilising inhibitors of RAS prenylation and signalling may be successful in the management of this disease. While preclinical studies investigating prenylation inhibitors, such as lovastatin, farnesyltransferase inhibitors (FTI) and geranylgeranyltransferase inhibitors (GGTI), have been promising, recent phase I/II clinical trials with FTI R115777 were disappointing, suggesting resistance to FTI monotherapy. To address this issue, the effects of FTI, GGTI and lovastatin alone and in combination were analysed in MM cell lines and primary cells. FTI treatment blocked H-RAS processing, but was ineffective at inhibiting K- and N-RAS prenylation because of alternative geranylgeranylation of these isoforms. However, combinations of FTI and GGTI or lovastatin were found to synergistically inhibit MM cell proliferation, migration, K- and N-RAS processing, RAS-to-mitogen-activated protein kinase signalling and to induce apoptosis. In contrast to FTI, lovastatin and some GGTI were found to cause intracellular accumulation of Rho proteins. Our results suggest that clinical efficacy of prenylation inhibitors in MM are limited by alternative prenylation of several small G-proteins, such as RhoB, K- and N-RAS. Furthermore, strategies combining FTI with GGTI or statins may provide greater efficacy in MM treatment.

Inflammation as a tumor promoter in cancer induction

Opposing effects of inflammation on cancer have been described. Acute inflammation usually counteracts cancer development, while chronic inflammation promotes cancer development. Just as inactivation of the p53 pathway may be universal in the neoplasia, the activation of the NFkappaB pathway may, conversely, be frequent in carcinogenesis, and a requirement for inflammation and promotion. TNF, a key pro-inflammatory cytokine when binding to TNF receptor 1 (TNFR1), may cause survival or apoptosis, dependent on biochemical modifications that determine the type of complex formed; one complex causes NFkappaB activation and gives a cell survival signal (pro-oncogenic), while the other (modified) complex recruits caspases and causes apoptosis (anti-oncogenic). Fas-ligand (FasL)-Fas interaction can also result in opposing effects on carcinogenesis due to similar mechanisms. While IL-6 counteracts apoptosis and can promote cancer development, interferons can increase DNA repair and stabilize p53, thereby be anti-oncogenic.

DNA methylation changes in multiple myeloma

Using a candidate gene approach, we analyzed the methylation status of the promoter-associated CpG islands of 11 well-characterized tumor suppressor genes by methylation-specific polymerase chain reaction in five multiple myeloma (MM) cell lines and 56 patients with malignant plasma cell disorders. The frequency of aberrant methylation among the patient samples was 46.4% for SOCS-1, 35.7% for p16, 21.4% for E-cadherin, 12.5% for DAP kinase and p73, 1.8% for p15, MGMT as well as RARbeta, and 0% for TIMP-3, RASSF1A and hMLH1. We found at least one hypermethylated gene in 80.4% of the primary patient samples, while 33.9% harbored two or more hypermethylated genes. For the first time, we show that p73 may be hypermethylated in MM and thus be involved in the pathogenesis of plasma cell disorders. Hypermethylation of p16 at diagnosis was associated with a poorer prognosis. In patients with plasma cell leukemia, we found frequent simultaneous hypermethylation of p16, E-cadherin and DAP kinase. We conclude that aberrant methylation of tumor suppressor genes is a common event in malignant plasma cell disorders and that there is a correlation between methylation patterns and clinical characteristics in MM patients.

Impaired osteoblastogenesis in myeloma bone disease: role of upregulated apoptosis by cytokines and malignant plasma cells

Bone remodelling is severely affected in myeloma bone disease as a consequence of skeletal metastatization of malignant plasma cells. We investigated whether defective bone replacement is dependent on increased osteoblast apoptosis and/or on deregulated events within the bone microenvironment. Circulating tumour necrosis factor (TNF)-alpha, interferon-gamma, interleukin (IL)-1beta, and IL-6 levels were higher in myeloma patients with overt bone disease, whose osteoblasts constitutively overexpressed Fas, DR4/DR5 complex as receptors to TNF-related apoptosis inducing ligand, intercellular adhesion molecule-1 (ICAM-1), and monocyte chemotactic protein-1 (MCP-1). They were functionally exhausted and promptly underwent apoptosis in vitro, in contrast to the minor tendency to death detected in control osteoblasts from patients without bone involvement and normal donors. Osteoblasts dramatically enhanced their apoptosis in co-cultures with MCC-2 myeloma cells and upregulated both ICAM-1 and MCP-1 in a manner similar to control osteoblasts. Pretreating MCC-2 cells with soluble ICAM-1 led to a striking inhibition of their adhesion to osteoblasts, suggesting that the ICAM-1/lymphocyte function-associated antigen-1 system plays a role in the reciprocal membrane contact to trigger apoptogenic signals. Our data suggest that, in the myeloma bone microenvironment, both high cytokine levels and physical interaction of malignant plasma cells with osteoblasts drive the accelerated apoptosis in these cells leading to defective new bone formation.

Cutaneous plasmablastic lymphoma in an HIV-positive male: an unrecognized cutaneous manifestation

Plasmablastic lymphoma (PBL) is a rare and relatively new entity originally described in HIV-infected individuals. This subset of Epstein-Barr-virus (EBV)-related non-Hodgkin lymphomas is now regarded as a distinct clinicopathological category of AIDS-associated lymphomas occurring preferentially in the oral cavity and showing a poor prognosis. We describe for the first time an EBV-associated PBL with an isolated cutaneous distribution on the lower extremities in an HIV-infected heterosexual male and point to the unique clinical, morphological and immunophenotypic characteristics of this lymphoma. The patient presented with fast growing solid and livid nodules on both legs. The large, blastic tumor cells showed the following immunophenotype: CD138+, CD45+, CD20-, CD10-, CD3-, CD30-, bcl-2-, bcl-6-, LMP-1- and EMA-. The proliferation fraction (Mib-1) was >90%. EBV association was demonstrated by in situ hybridization (EBV-encoded RNAs 1/2). Polymerase-chain-reaction-based DNA analysis demonstrated a clonal IgH rearrangement in the absence of a bcl-2/IgH translocation. PBL in HIV patients may occur not only in the oral cavity, but can probably involve any other organs including the skin.

Overexpression of PDZK1 within the 1q12-q22 amplicon is likely to be associated with drug-resistance phenotype in multiple myeloma

We investigated DNA copy number aberrations in 37 cell lines derived from multiple myelomas (MMs) using comparative genomic hybridization, and 11 (29.7%) showed high-level gain indicative of gene amplification at 1q12-q22. A corresponding transcriptional mapping using oligonucleotide arrays extracted three up-regulated genes (IRTA2, PDZK1, and S100A6) within the smallest region of overlapping in amplifications. Among them PDZK1 showed amplification and consequent overexpression in the MM cell lines. Amplification of PDZK1 was observed in primary cases of MM as well. MM cell lines with amplification of PDZK1 exhibited the resistance to melphalan-, cis-platin-, and vincristin-induced cell death compared with MM cell lines without its amplifications. Furthermore, down-regulation of PDZK1 with an anti-sense oligonucleotide sensitized a cell line KMS-11 to melphalan, cis-platin, and vincristin. Taken together, our results indicate that PDZK1 is likely to be one of targets for 1q12-q22 amplification in MM and may be associated with the malignant phenotype, including drug resistance, in this type of tumor.

Osteoclast-like cell formation by circulating myeloma B lymphocytes: role of RANK-L

Excessive bone resorption in multiple myeloma (MM), a malignancy of B lymphoid origin, is mediated through osteoclasts, which respond to local osteoclast-activating factors produced by tumor cells within the bone marrow microenvironment. Direct bone resorption by myeloma cells is investigated in the present study, since a connection between B lymphocytes and osteoclast differentiation pathways has been recently postulated in mice. Peripheral CD19+ B lymphocytes isolated from 10 myeloma patients with multiple osteolytic lesions and 10 healthy donors were cultured in the presence of M-CSF and RANK-L, two major osteoclast-activating factors. The TRAP expression and resorption of bone substrates were employed to evaluate osteoclast differentiation. MM patients were characterized by the presence of circulating B lymphocytes endowed with both phenotypical and functional properties of osteoclast-like cells in vitro when stimulated with RANK-L. The absence of these characteristics in B lymphocytes from healthy donors indicates that the transformation can be ascribed to the presence of clonogenic B cells in patients with MM. Clonotypic B lymphocytes may contribute to the pathogenesis of bone disease in MM by acting as RANK-L-dependent osteoclast progenitors.

Effects of all-trans retinoic acid (ATRA) on human myeloma cells

All-trans retinoic acid (ATRA) is a natural oxidative metabolite of Vitamin A (retinol) and is known to be a regulator of cell proliferation differentiation, especially in various malignant cells. The cyto-differentiating action of ATRA has led to its usage in the treatment of several malignancies, particularly acute promyelocytic leukemia (APL). There have been many reports regarding the cell biological effects of ATRA on human myeloma cells and a few clinical trials. Most of these reports have revealed growth inhibition by ATRA mediated by down-regulation of the IL-6/IL-6R auto/paracrine loop, and upregulation of p21/Cip1. Here, we review previous reports and introduce experimental results obtained using various myeloma cell lines established in our laboratory.

Transcriptional inactivation of STAT3 by PPARgamma suppresses IL-6-responsive multiple myeloma cells

Multiple myeloma (MM) remains largely incurable despite conventional and high-dose therapies. Therefore, novel biologically based treatment approaches are urgently required. Here we demonstrate that expression of peroxisome proliferator-activated receptor gamma (PPARgamma) in MM cells and its agonists 15-d-PGJ2 and troglitazone completely abolished IL-6-inducible MM cell proliferation and induced apoptosis through affecting expression of multiple cell cycle or apoptosis genes, whereas PPARgamma antagonist GW9662 and PPARalpha agonist WY14643 did not display this inhibitory effect. These PPARgamma agonists significantly inhibited DNA binding and transactivation of STAT3 bound to the promoter of target genes in chromatin, but did not affect the expression of IL-6 receptor and phosphorylation of JAK/STAT3, MAPK, and PI3K/Akt. Interestingly, although inactivation of STAT3 by PPARgamma agonists is in a PPARgamma-dependent manner, the molecular mechanism by which two structurally distinct PPARgamma agonists suppress IL-6-activated STAT3 shows the divergent interactions between PPARgamma and STAT3 including direct or SMRT-mediated association.

Signalling molecules and cytokine production in T cells of multiple myeloma-increased abnormalities with advancing stage

T-cell immune dysfunction in patients with malignant tumours has been attributed to the altered expression of components of the T-cell receptor (TCR)/CD3 complex and their associated intracellular protein tyrosine kinases. In this study, four-colour flow cytometry was applied to study the surface bound molecules TCRalphabeta, CD28, CD152 and CD154 involved in T-cell signalling and the signal transduction molecules CD3zeta, p56lck, p59fyn, ZAP-70 and phosphatidyl-inositol-3 kinase (PI3-k) as well as the intracellular cytokines interferon-gamma (IFN-gamma), interleukin (IL)-4 and IL-2 as a functional read-out of non-stimulated and superantigen (staphylococcus enterotoxin B)-stimulated blood T cells of multiple myeloma (MM) patients at different stages of the disease. Multiple abnormalities were demonstrated in the CD4 and CD8 populations, both under non-stimulated and superantigen-stimulated conditions. There was a marked reduction, particular in advanced stage MM, in the proportion of CD4 and CD8 cells expressing CD28, CD152, CD3zeta, p56lck, ZAP-70 and PI3-k. The level of intracellular T-cell cytokines (IFN-gamma, IL-2 and IL-4) was normal or increased in non-stimulated cells but activation-induced cytokine production was impaired. These results illustrated profound and multiple T-cell signalling defects, from the surface and down-stream, consistent with involvement of a master T-cell function, especially in advanced stage MM. These data should be taken into consideration when developing immune-based therapeutic approaches and when applying new emerging technologies that aim to restore T-cell functions.

Protein kinase C-delta is commonly expressed in multiple myeloma cells and its downregulation by rottlerin causes apoptosis

The growth and proliferation of multiple myeloma (MM) cells are influenced by various cytokines produced by bone marrow stromal cells. As cytokine interaction between malignant plasma cells and neighbouring stromal cells is important in the pathogenesis of MM, the understanding of intracellular signalling events elicited by this interaction is of central importance. Recent reports have shown that protein kinase C (PKC) is directly involved in modulating apoptosis in different cells types, including those of haematopoietic neoplasms. In the present study, we analysed the expression patterns of PKC isoforms in the myeloma cell lines U266, RPMI-8226 and K620. This analysis demonstrated common expression of PKC-delta, PKC-iota, PKC- micro and PKC-zeta in all three myeloma cell lines. PKC-delta expression in plasma cells from 11 patients with MM was also shown by immunohistochemistry, utilizing a monoclonal mouse anti-human PKC-delta antibody. U266 cells treated with the broad PKC inhibitor safingol (l-threo-dihydrosphingosine) or the PKC-delta-specific inhibitor rottlerin (3'-[(8-Cinnamoyl-5,7-dihydroxy-2,2-dimethyl-2H-1-benzopyran-6-yl)methyl]-2',4',6'-trihydroxy-5'-methylacetophenone) showed decreased PKC-delta in the particulate fraction and resulted in significant apoptosis. Primary myeloma cells also showed apoptosis after treatment with the PKC inhibitors, as detected by both flow cytometric and morphological evaluation. Our results indicate that PKC-delta is commonly expressed in myeloma cells and plays an important role in plasma cell survival.

SOCS-1, a negative regulator of cytokine signaling, is frequently silenced by methylation in multiple myeloma

The suppressor of cytokine signaling (SOCS) family of proteins has been implicated in the negative regulation of several cytokine pathways, particularly the receptor-associated tyrosine kinase/signal transducer and activator of transcription (Jak/STAT) pathways of transcriptional activation. SOCS-1 (also known as JAB and SSI-1) inhibits signaling by many cytokines. Because of the previously observed hypermethylation-associated inactivation of SOCS-1 in hepatocellular carcinoma and the critical role of interleukin-6 (IL-6) as a survival factor in multiple myeloma (MM), we examined CpG island methylation of the SOCS-1 gene in MM cell lines and primary MM samples. Aberrant SOCS-1 methylation was found in the IL-6-dependent MM cell lines U266 and XG1, which correlated with transcriptional silencing. Treatment of these cell lines with the demethylating agent 5-aza-2'-deoxycytidine (DAC) up-regulated SOCS-1 expression. Methylation-associated inactivation of SOCS-1 in hematopoietic cell lines correlated with greater sensitivity to the chemical JAK inhibitor AG490. Using methylation-specific polymerase chain reaction (MSP), we found that SOCS-1 is hypermethylated in 62.9% (23/35) of MM patient samples. In contrast, methylation analysis of malignant lymphomas of various histologies revealed SOCS-1 hypermethylation in only 3.2% (2/62), and there was no methylation of SOCS-1 in normal peripheral blood leukocytes or bone marrow cells. We conclude that SOCS-1 is frequently inactivated by hypermethylation in MM patients. Silencing of the SOCS-1 gene may impair negative regulation of the Jak/STAT pathway and therefore result in greater responsiveness to cytokines, thus supporting survival and expansion of MM cells.

An unusual H-Ras mutant isolated from a human multiple myeloma line leads to transformation and factor-independent cell growth

Multiple myeloma (MM) is an incurable plasma cell malignancy. To investigate biochemical lesions associated with MM, we constructed an expression cDNA library from the OPM-2 human myeloma line. A highly transforming H-Ras mutant was identified by transfection analysis using NIH 3T3 cells. DNA sequencing demonstrated a single-point mutation at position 117 located in the guanine nucleotide-binding site resulting in a lysine-to-glutamic acid substitution. This mutant, H-Ras (K117E), was found to be constitutively activated in terms of GTP binding. We compared the biological effects of H-Ras (K117E) and H-Ras (G12V) in 32D murine hematopoietic progenitor cells. Whereas both Ras proteins are constitutively activated, 32D cells expressing H-Ras (G12V) are still dependent on IL-3 for survival and proliferation while cells carrying H-Ras (K117E) become IL-3 independent. Similar experiments conducted with the B9 line, an IL-6-dependent hybridoma, also demonstrated that B9/H-Ras (K117E) became IL-6-independent. Expression of H-Ras (K117E) in the human IL-6-dependent ANBL-6 myeloma line resulted in enhanced proliferation at suboptimal concentrations of IL-6. These observations suggest that H-Ras mutations at the binding site for the GTP nucleotide ring structure may also represent activating lesions and have additional biological effects when compared to previously described Ras mutants.