Multiple Myeloma: Increasing Evidence for a Multistep Transformation Process

Bone marrow angiogenesis in multiple myeloma

Angiogenesis is a constant hallmark of multiple myeloma (MM) progression and has prognostic potential. It is induced by plasma cells via angiogenic factors with the transition from monoclonal gammopathy of undetermined significance (MGUS) to MM, and probably with loss of angiostatic activity on the part of MGUS. The pathophysiology of MM-induced angiogenesis is complex and involves both direct production of angiogenic cytokines by plasma cells and their induction within the microenvironment. The latter are secreted by stromal cells, endothelial cells (EC) and osteoclasts, and promote plasma cell growth, survival and migration, as well as paracrine cytokine secretion and angiogenesis in the bone marrow milieu. Angiogenesis is also supported by inflammatory cells following their recruitment and activation by plasma cells. Finally, circulating EC and endothelial precursor cells (EPC) contribute to the neovascularization, and the presence of EPC suggests that vasculogenesis (new vessel formation from EPC) may also contribute to the full MM vascular tree.

Targeting NF-κB in hematologic malignancies

The transcription factor nuclear factor kappa B (NF-kappaB) can intervene in oncogenesis by virtue of its capacity to regulate the expression of a plethora of genes that modulate apoptosis, and cell survival as well as proliferation, inflammation, tumor metastasis and angiogenesis. Different reports demonstrate the intrinsic activation of NF-kappaB in lymphoid and myeloid malignancies, including preneoplastic conditions such as myelodysplastic syndromes, underscoring its implication in malignant transformation. Targeting intrinsic NF-kappaB activation, as well as its upstream and downstream regulators, may hence constitute an additional approach to the oncologist's armamentarium. Several small inhibitors of the NF-kappaB-activatory kinase IkappaB kinase, of the proteasome, or of the DNA binding of NF-kappaB subunits are under intensive investigation. Currently used cytotoxic agents can induce NF-kappaB activation as an unwarranted side effect, which confers apoptosis suppression and hence resistance to these drugs. Thus, NF-kappaB inhibitory molecules may be clinically useful, either as single therapeutic agents or in combination with classical chemotherapeutic agents, for the treatment of hematological malignancies.

Role of 18F-FDG PET/CT in the assessment of bone involvement in newly diagnosed multiple myeloma: preliminary results

PURPOSE

Multiple myeloma (MM) is a malignant B cell and plasma cell disorder which involves the skeleton in more than 80% of patients at diagnosis. The aim of this study was to compare whole-body X-ray (WBXR), MRI and (18)F-FDG PET/CT in patients with MM.

METHODS

The study population comprised 28 newly diagnosed MM patients. Findings of (18)F-FDG PET/CT were compared with those of WBXR and MRI with regard to the number and site of lesions detected.

RESULTS

Comparing (18)F-FDG PET/CT and WBXR, it was found that in 16/28 pts (57%) (18)F-FDG PET/CT detected more lesions, all of which were located in the skeleton. Nine of these 16 patients had a completely negative WBXR survey. In 12/28 pts (43%) the two methods yielded equivalent findings. Comparing (18)F-FDG PET/CT and MRI, it was found that in 7/28 pts (25%), (18)F-FDG PET/CT detected more lytic bone lesions, all of which were located outside the field of view of MRI (bone lesions in six cases and a soft tissue lesion in one). In 14/28 pts (50%), (18)F-FDG PET/CT and MRI detected the same number of lesions in the spine and pelvis, while in 7/28 pts (25%) MRI detected an infiltrative pattern in the spine whereas (18)F-FDG PET/CT was negative.

CONCLUSION

(18)F-FDG PET/CT appears to be more sensitive than WBXR for the detection of small lytic bone lesions, whereas it has the same sensitivity as MRI in detecting bone disease of the spine and pelvis. On the other hand, MRI may be superior to (18)F-FDG PET/CT in diagnosing an infiltrative pattern in the spine. Therefore, careful evaluation of MM bone disease at diagnosis should include both MRI of the spine and (18)F-FDG PET/CT.

Etodolac induces apoptosis and inhibits cell adhesion to bone marrow stromal cells in human myeloma cells

OBJECTIVES

Cyclooxygenase-2 (COX-2) is reported to regulate apoptosis and to be an important cellular target for therapy.

METHODS

We examined whether etodolac, meloxicam, and thalidomide inhibited proliferation and induced apoptosis in myeloma cell lines (RPMI 8226 and MC/CAR cells).

RESULTS

Etodolac induced apoptosis more strongly compared with thalidomide or meloxicam. Etodolac induced down-regulation of Bcl-2 protein and mRNA, activation of Caspase-9, -7 and -3, cIAP-1 and Survivin, and loss of mitochondrial membrane potential in a dose-dependent manner. In addition, when myeloma cells were coincubated with 50 microM etodolac on bone marrow stromal cells (BMSCs), myeloma cell adhesion to BMSCs was significantly inhibited compared with thalidomide or meloxicam coincubation, and the adhesion molecules VLA-4, LFA-1 (CD11a), CXCX4, and CD44 were suppressed on myeloma cells treated with etodolac. Moreover, 50-100 microM racemate of etodolac significantly inhibited the proliferation of myeloma cells compared to 100 microM R-etodolac or S-etodolac.

CONCLUSIONS

Etodolac induced loss of mitochondrial membrane potential and apoptosis via a COX-2-independent pathway, suppressed the expression of adhesion molecules, and inhibited myeloma cell adhesion to BMSCs compared with thalidomide or meloxicam. The activities of etodolac potentially extend to the treatment of patients with myeloma resistant to standard chemotherapy, including thalidomide.

The Selective Estrogen Receptor Modulator 4-Hydroxy Tamoxifen Induces G1 Arrest and Apoptosis of Multiple Myeloma Cell Lines

Multiple myeloma (MM) is an incurable hematological malignancy for which new therapeutic strategies should be envisaged. The selective estrogen receptor modulator (SERM), 4-hydroxy tamoxifen (4-OHTam), in the range of 1 to 10 micro M, was able to impair the cell proliferation of MM cell lines. This was achieved by blocking cells at the G1 phase of the cell cycle and by inducing apoptosis. This cellular response was observed in five out of six tested cell lines, all five expressing both alpha and beta estrogen receptor forms. No modifications of Bcl-2, Bcl-X, and Bax levels were observed, as well as no changes in Pi3K/Akt and JAK/STAT pathways that are often constitutively active in these cells. The signalization of 4-OHTam-induced cell death needs further investigation.

Resveratrol induces apoptosis of human malignant B cells by activation of caspase-3 and p38 MAP kinase pathways

Red wine polyphenol, trans-resveratrol (trans-3,4',5-trihydroxy stilbene), has potent chemopreventive effects against various tumors. In this study, we found for the first time that resveratrol rapidly induces S phase cell cycle arrest of human malignant B cells including myeloma cells in dose- and time-dependent manners, followed by S phase cell cycle arrest through ATM/Chk pathway. Resveratrol-induced apoptosis occurs in association with the activation of caspase-3 and the loss of mitochondrial transmembrane potentials. In addition, resveratrol induces the phosphorylation of p38 MAP kinase, and specific inhibition of p38 MAP kinase abolishes the resveratrol-induced apoptosis, indicating that activation of the p38 MAP kinase pathway is required for inducing apoptosis in malignant B cells. These results suggest that resveratrol may have potential as a novel therapeutic agent for the patients with B cell malignancies including multiple myeloma.

Unusual cyst-like lesions in the parapharyngeal space associated with recurrence of tongue carcinoma

A 54-year-old male presented with the complaint of a painful sore on the left side of his tongue. Our examination found an ulcer 15 x 20 mm in size on the left edge of the tongue, with peripheral indurations. The lesion was diagnosed histopathologically as squamous cell carcinoma (T2N0M0). Consequently, the lesion was surgical removed and radical neck dissection was performed. Four months after the operation, two unusual cyst-like lesions were identified in the parapharyngeal space by CT and MRI. A biopsy specimen revealed recurrent carcinoma with a cyst-like structure. The route of the tumor metastasis into the parapharyngeal space was obscured, but it was speculated that the excessive lymph accumulation was due to a lymphatic occlusion caused by the surgical procedure, proliferation of the metastatic carcinoma, or stagnation and accumulation of tissue fluid caused by parapharyngeal invasion by the recurrent lesion.

Methylation status of fragile histidine triad (FHIT) gene and its clinical impact on prognosis of patients with multiple myeloma

Aberrant methylation of tumor suppressor genes (TSG) has been studied in multiple myeloma (MM). We determined the methylation status of the FHIT (fragile histidine triad) gene, a putative TSG, in 48 patients with MM. Clinical association with its methylation status was then analyzed. The FHIT gene methylation was observed in 21 of the 48 patients (44%). No association between FHIT gene methylation and clinical variables such as age, gender and clinical stage was found. However, the estimated 50% survival time of the methylated group was significantly shorter than that of the unmethylated group (18.2 vs. 45.1 months, P < 0.05). Univariate analysis revealed adverse prognostic factors: FHIT gene methylation (P = 0.028), poor performance status (I to IV, P = 0.002), anemia (< or =8.5 g/dL, P = 0.007), hypoalbuminemia (< or =3.5 g/dL, P < 0.002), high serum C-reactive protein levels (>0.5 mg/dL, P = 0.002), elevated beta-2-microglobulin serum levels (>6.5 mg/L, P < 0.001), and treatments not including autologous peripheral blood stem cell transplantation (auto-PBSCT) (P = 0.007). Multivariate analysis identified FHIT gene methylation [hazard ratio (HR) 1.722, 95% confidence interval (CI) 1.150-2.603, P = 0.009], elevated beta-2-microglobulin serum levels (>6.5 mg/L, HR 2.005, 95% CI 1.035-3.937, P = 0.004), and treatments not including auto-PBSCT are independent predictive variables. These findings indicate that aberrant methylation of the FHIT gene is an independent adverse prognostic factor in MM.

Targeted therapy in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is an incurable malignancy. Recent insights into its biology has allowed the use of novel therapies targeting not only the deregulated intracellular signaling in MM cells but also its interaction with the bone marrow microenvironment that confers drug resistance, growth, and survival advantage to the malignant cells.

METHODS

We review and summarize the recent advances in our knowledge of myeloma biology as well as the mechanism of action and clinical efficacy for novel therapeutic agents in clinical trials.

RESULTS

Several novel therapeutic agents are currently in clinical trials. Thalidomide is already established for both initial and salvage treatment. Bortezomib is being tested alone and in combination with conventional chemotherapy in various settings. Other agents are less effective in producing response but have been able to stabilize disease in patients with relapsed and/or refractory disease, such as arsenic trioxide, farnesyltransferase inhibitors, 2-methoxyestradiol, and vascular endothelial growth factor receptor inhibitors. Insights into drug resistance mechanism have also led to the development of novel agents that sensitize myeloma cells to chemotherapy (Bcl-2 antisense). Gene expression studies have in many instances identified pathways other than the intended target of the drug and have provided insights into the therapeutic mechanisms.

CONCLUSIONS

In the future, patients with MM will have more therapeutic options available than ever before. The challenge will be to identify patient subgroups that will benefit most from the different therapies and then determine how these biologically based therapies could be combined and incorporated into the overall management of patients.

Sustained remission including marked regression of a paravertebral plasmacytoma in a patient with heavily pretreated, relapsed multiple myeloma after treatment with bortezomib

Despite advances in systemic and supportive therapies, multiple myeloma (MM) has remained an incurable disease, which underlines the need for novel approaches to therapy. Recent data indicate that the proteasome-inhibitor bortezomib has marked activity with manageable toxicity in relapsed and refractory MM. We here report on a patient suffering from heavily pretreated and refractory MM with a paravertebral tumor manifestation. After three cycles of bortezomib, the patient achieved near-complete remission, as well as a nearly complete regression of the paravertebral tumor. This case further documents that bortezomib is an effective novel therapy for MM.

Gene expression profiling and multiple myeloma

Gene expression profiling is a powerful tool through which the biology of multiple myeloma can be dissected. We will describe in this chapter how early studies using this technology have provided meaningful insights into myeloma biology, have led to the identification of new therapeutic targets, and have identified powerful prognostic and pharmacogenomic markers. Specifically, we will demonstrate that gene expression profiling can be used to segregate myeloma patients into prognostic categories within which known IgH translocation signatures can be readily defined. We also show that expression signatures can identify patients with chromosome 13 deletion. Finally, we demonstrate that global gene expression signatures can be distilled to short lists of three genes or more which together impart clinical outcome information, which is significantly more powerful than any previously defined prognostic tool. Expression profiling has also led to the identification of a number of new therapeutic targets not only in myeloma cell survival but also in the pathogenesis of the osteolysis which is a hallmark of this disease.

Therapeutic renaissance of thalidomide in the treatment of haematological malignancies

Very few drugs had a history similar to that of thalidomide (alpha-N-[phthalimido] gluramide). First introduced in the late 1950s in Germany, in 1961 thalidomide was withdrawn due to its teratogenic effects. More than three decades after, it is attracting growing interest because of its reported immunomodulatory and anti-inflammatory properties. The discovery that thalidomide inhibits angiogenesis led to preclinical and clinical trials as an anticancer agent in the treatment of solid tumours and haematological malignancies, as summarized in this review article. More recently, structural analogues of thalidomide have been synthesized in order to explore potential molecular targets of thalidomide, as well as to identify new agents with improved therapeutic efficacy.

High incidence and intraclonal heterogeneity of chromosome 11 aberrations in patients with newly diagnosed multiple myeloma detected by multiprobe interphase FISH

In multiple myeloma, additional copies of chromosome 11 material, reported to confer an unfavorable prognosis, have been found in 20-45% of patients. To assess the incidence and extent of chromosome 11 aberrations, we performed interphase fluorescence in situ hybridization on CD138+ bone marrow plasma cells of 50 newly diagnosed myeloma patients, using seven locus-specific probes for chromosome 11, one for 13q14.3, and a probe set for translocation t(11;14). In 33 of 50 patients, chromosome 11 aberrations were found. Results indicated a marked intraclonal heterogeneity: in 13 patients, trisomy 11; in 10 patients, subclones with trisomy 11 and partial trisomies 11q coexisted; in 6 patients, only a partial trisomy 11q; and in 6 patients, a tetrasomy or partial tetrasomy 11. The coexistence of subclones with varying extent and copy numbers of chromosome 11 material indicates ongoing structural changes and clonal evolution. Hybridization results delineated 11q23 and 11q25 as the most frequently gained regions, which supports a relevant pathogenetic role of genes on 11q23 and 11q25. To confirm the high incidence of 11q23 gains, a further 50 patients (total n=100) were analyzed for 11q23 and 13q14.3. Myeloma with gains of 11q23 showed a low frequency of deletion 13q14.3 and may prove to be a distinct subgroup of this disease.

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.

Multiple myeloma of the thoracic spine developed at the previous trauma site: case report

The precise nature of the underlying plasma cell dyscrasias is not well understood. Even today, no causative factor has been found for this disease. It has been suggested that, several factors may act together in the development of this disease. This is a report of a 62-year-old man who initially had a T7 compression fracture and developed a multiple myeloma two years later at that site and at the adjacent vertebral level (T7-T8), respectively. Although the notion that trauma would initiate such a malignancy is speculative, the preceding trauma may be a causative factor in plasma cell dyscrasias.

Ploidy status rarely changes in myeloma patients at disease progression

Hyperdiploid and non-hyperdiploid multiple myeloma represents distinct biological entities characterized by different patterns of genetic changes. We sought to determine whether ploidy category (non-hyperdiploid versus hyperdiploid) remains stable over time from diagnosis to progression. Of the 43 patients studied (39 by flow cytometry DNA index and 4 by a FISH-based index), only five (12%) altered their ploidy status at progression. In three of these patients, the change may possibly be attributable to technical artifacts because of the low absolute change in DNA index. For those who retain their ploidy subtypes, the DNA index change minimally (3.75+/-4.87%). It would appear that the initiating genetic events underlying hyperdiploid and non-hyperdiploid MM that marks them out as distinct entities continue to dominate and persist during disease evolution and progression.

Role of IL-6 and CD23 in the resistance to growth arrest and apoptosis in LCL41 B lymphoma cells

Interleukin-6 (IL-6) is a growth and survival factor in Epstein-Barr virus (EBV)-infected B lymphoma cells and IL-6 antagonists have been used in clinical practice for this pathology. We thus wanted to investigate the effect of the IL-6 receptor antagonist Sant7 on proliferative and anti-apoptotic signals in the IL-6-secreting LCL41 B lymphoid cells, taken from a patient with EBV-induced lymphoproliferative disorder. Results show efficient inhibition of constitutive Stat3 activation by Sant7. However, this inhibition is associated with marginal induction of apoptosis and with minor decrease of cell proliferation, contrary to the effect of the Jak kinase inhibitor AG490, which down-regulates both proliferation and Stat3 activation. Anti-apoptotic markers such as Bcl-xL or Mcl-1 are constitutively expressed in these cells, and their expression is not affected by Sant7 treatment. Inhibition of Stat3 activation is therefore not sufficient to prevent proliferation and to induce apoptosis in these cells. In addition, low cell density is a condition favouring inhibition of cell clustering and anti-proliferative Sant7 activity. A marked inhibition of cell cluster formation and proliferation is achieved by antibody treatment against the CD23 mature B cell surface marker expressed in LCL41 cells. These findings may thus contribute to the identification of possible resistance mechanisms to growth arrest in B cell lymphoproliferative conditions.

Antigen-specific memory B cell development

Helper T (Th) cell-regulated B cell immunity progresses in an ordered cascade of cellular development that culminates in the production of antigen-specific memory B cells. The recognition of peptide MHC class II complexes on activated antigen-presenting cells is critical for effective Th cell selection, clonal expansion, and effector Th cell function development (Phase I). Cognate effector Th cell-B cell interactions then promote the development of either short-lived plasma cells (PCs) or germinal centers (GCs) (Phase II). These GCs expand, diversify, and select high-affinity variants of antigen-specific B cells for entry into the long-lived memory B cell compartment (Phase III). Upon antigen rechallenge, memory B cells rapidly expand and differentiate into PCs under the cognate control of memory Th cells (Phase IV). We review the cellular and molecular regulators of this dynamic process with emphasis on the multiple memory B cell fates that develop in vivo.

The survival of IL-6-dependent myeloma cells critically relies on their capability to transit the G1 to S phase interval of the cell cycle

Interleukin-6 (IL-6) has an essential role in the initial progression of myeloma cell tumours. IL-6 triggers proliferation of these cells via the Ras-mitogen-activated protein kinase (MAPK) cascade and is thought to promote their survival via signal transducer and activator of transcription (STAT) pathway-dependent regulation of Bcl-2 family antiapoptotic members. Using IL-6-dependent murine B9 hybridoma/plasmacytoma cells, we here report that exiting the cell cycle G1 phase is a crucial step contributing to maintain viability. We show that (1) drug-mediated reversible G1 arrest triggered apoptosis despite the presence of IL-6; (2) a short IL-6 pulse to G1-arrested cells was sufficient to induce S phase entry and prevent apoptosis; and (3) phorbol ester and related derivatives promoted S phase entry and survival of IL-6-starved cells without up-regulating bcl-XL expression. Furthermore, that the MAPK kinase (MEK) 1/2 inhibitor, U0126, blocked proliferation and induced death of B9 cells indicate that IL-6 may not exert its survival effect primarily through bcl-XL and emphasizes the key role of Ras-MAPK cascade elements in the regulation of myeloma growth/viability.

p16 gene methylation lacks correlation with angiogenesis and prognosis in multiple myeloma

Methylation of p16 gene is a relatively frequent molecular finding in multiple myeloma (MM), but its clinical implication is disputable. Cell cycle regulators are now recognized as active in the control of angiogenesis, which is an integral component of pathogenesis and a target for new treatment modalities of this disease. On such background, we focused on determining whether loss of p16 function by methylation could be associated with increased angiogenesis and VEGF expression, and the prognostic relevance of p16 methylation in 50 untreated, newly diagnosed MM patients. Thirty-one percent (13/42) of 42 patients assessable for p16 gene methylation showed to be methylation-positive. High-angiogenesis was present in 73% of cases, but methylation of the p16 gene did not associate with angiogenesis or with VEGF expression. Also, p16 methylation did not show prognostic relevance or correlation with the clinical and laboratory parameters of prognostic significance in univariate analysis. P16 immunoexpression presented only a faint agreement with the molecular study. Therefore, p16 methylation seems to have no correlation with angiogenesis and VEGF expression, neither with overall and event-free survival in MM patients. Besides, P16 immunohistochemistry seems inadequate to substitute the molecular study of methylation in this type of tumor cells. Additional studies are needed to clarify the correspondence between the epigenetic alteration of the p16 gene and its protein immunexpression, and the clinical relevance of p16 methylation in MM patients.

C-kit receptor (CD117) expression on plasma cells in monoclonal gammopathies

The surface expression of CD117 antigen (c-kit) on plasma cells from 158 multiple myeloma (MM), 12 plasma cell leukemia (PCL), 7 MGUS, 7 IgM lymphoplasmacytic lymphoma patients and 10 healthy subjects has been analyzed by flow cytometry using triple staining with the monoclonal antibodies CD138, CD117 and CD38. The antigen expression intensity was calculated as relative fluorescence intensity (RFI) and for direct quantitative analysis the QuantiBRITE test (Becton Dickinson) was applied. Antibody bounding capacity (ABC) was calculated using QuantiCALC software. CD117 antigen was present in 49/158 MM, 5/12 PCL and 5/7 MGUS patients. The RFI values ranged from 0.2 to 20.2 in particular MM patients (mean: 11.0+/-5.3; median 11.5) while the number of CD117 binding sites (ABC) on MM plasma cells ranged from 637 to 6217 (mean: 3029+/-1568; median 2946) (r=0.8328). In responsive to chemotherapy c-kit positive MM patients the percentage of CD117+ plasma cells in the bone marrow decreased significantly while in c-kit negative MM patients the percentage of CD117+ cells in bone marrow did not change and remained in the normal limits. When comparing the clinical and biological disease characteristics (monoclonal protein isotype, albumin, beta2-microglobulin, lactate dehydrogenase, stage of disease, response to chemotherapy, survival time) of c-kit positive and c-kit negative cases, no significant differences were found. In CD117 positive PCL cases expression of CD117 was detected in bone marrow plasma cells as well as in peripheral blood plasma cells. Normal plasma cells and those in IgM lymphoplasmacytic lymphoma did not show reactivity for the CD117 antigen. We conclude that it may be rationale to consider usefulness of therapy with tyrosine kinase inhibitors in the management of c-kit positive plasma cell proliferations. In one third of MM and PCL patients c-kit antigen could be considered as a "tumor associated marker" and together with CD38 and CD138 it may be of value for the identification of the malignant clone in minimal residual disease as it was first suggested by Spanish authors.

Baicalein, a component of Scutellaria radix from Huang-Lian-Jie-Du-Tang (HLJDT), leads to suppression of proliferation and induction of apoptosis in human myeloma cells

In the search for a more effective adjuvant therapy to treat multiple myeloma (MM), we investigated the effects of the traditional Chinese herbal medicines Huang-Lian-Jie-Du-Tang (HLJDT), Gui-Zhi-Fu-Ling-Wan (GZFLW), and Huang-Lian-Tang (HLT) on the proliferation and apoptosis of myeloma cells. HLJDT inhibited the proliferation of myeloma cell lines and the survival of primary myeloma cells, especially MPC-1- immature myeloma cells, and induced apoptosis in myeloma cell lines via a mitochondria-mediated pathway by reducing mitochondrial membrane potential and activating caspase-9 and caspase-3. Further experiments confirmed that Scutellaria radix was responsible for the suppressive effect of HLJDT on myeloma cell proliferation, and the baicalein in Scutellaria radix showed strong growth inhibition and induction of apoptosis in comparison with baicalin or wogonin. Baicalein as well as baicalin suppressed the survival in vitro of MPC-1- immature myeloma cells rather than MPC-1+ myeloma cells from myeloma patients. Baicalein inhibited the phosphorylation of IkB-α, which was followed by decreased expression of the IL-6 and XIAP genes and activation of caspase-9 and caspase-3. Therefore, HLJDT and Scutellaria radix have an antiproliferative effect on myeloma cells, especially MPC-1- immature myeloma cells, and baicalein may be responsible for the suppressive effect of Scutellaria radix by blocking IkB-α degradation. (Blood. 2005;105:3312-3318)

The structure, expression and function prediction of DAZAP2, a down-regulated gene in multiple myeloma

In our previous studies, DAZAP2 gene expression was down-regulated in untreated patients of multiple myeloma (MM). For better studying the structure and function of DAZAP2, a full-length cDNA was isolated from mononuclear cells of a normal human bone marrow, sequenced and deposited to Genbank (AY430097). This sequence has an identical ORF (open reading frame) as the NM_014764 from human testis and the D31767 from human cell line KG-1. Phylogenetic analysis and structure prediction reveal that DAZAP2 homologues are highly conserved throughout evolution and share a polyproline region and several potential SH2/SH3 binding sites. DAZAP2 occurs as a single-copy gene with a four-exon organization. We further noticed that the functional DAZAP2 gene is located on Chromosome 12 and its pseudogene gene is on Chromosome 2 with electronic location of human chromosome in Genbank, though no genetic abnormalities of MM have been reported on Chromosome 12. The ORF of human DAZAP2 encodes a 17-kDa protein, which is highly similar to mouse Prtb. The DAZAP2 protein is mainly localized in cytoplasm with a discrete pattern of punctuated distribution. DAZAP2 may associate with carcinogenesis of MM and participate in yet-to-be identified signaling pathways to regulate proliferation and differentiation of plasma cells.

Clonal plasma cells from monoclonal gammopathy of undetermined significance, multiple myeloma and plasma cell leukemia show different expression profiles of molecules involved in the interaction with the immunological bone marrow microenvironment

The immunological bone marrow (BM) microenvironment plays a major role in controlling growth and survival of clonal plasma cells (PC); this might translate into different patterns of expression of molecules involved in immune responses on PC from different types of monoclonal gammopathies (MG). We have studied the expression of a group of nine such molecules on both BMPC and the plasma of 61 newly diagnosed MG patients (30 MG of undetermined significance (MGUS), 27 multiple myeloma (MM) and four plasma cell leukemia (PCL)) and five normal individuals. Clonal PC from all MG displayed significantly increased levels of CD56, CD86 and CD126, and decreased amounts of CD38 (P<0.001). Additionally, HLA-I and beta2-microglobulin were abnormally highly expressed in MGUS, while CD40 expression was decreased in MM and PCL (P<0.05). Interestingly, a progressive increase in the soluble levels of beta2-microglobulin was found from MGUS to MM and PCL patients (P=0.03). In contrast, all groups showed similar surface and soluble amounts of CD126, CD130 and CD95, except for increased soluble levels of CD95 observed in PCL. Overall, those phenotypic differences are consistent with increased antigen presentation and costimulatory capacities in MGUS, which progressively deteriorate in malignant MG (MM and PCL).

Advances in myeloma genetics and prospects for pharmacogenomic testing in multiple myeloma

Pharmacogenomic studies in multiple myeloma, a neoplasia of clonally expanded malignant bone marrow plasma cells, are helping to set the stage for individualized therapy. Although relatively few in numbers, these studies are already providing new therapeutic targets and avenues for drug discoveries as well as contributing to novel prognostic markers in multiple myeloma. High-throughput mutation screening of the kinome promises to identify further novel targets for therapy. Genetics and gene expression profiling technology have improved molecular-based patient stratification and prognostic staging, expanded knowledge of the molecular mechanism of chemotherapeutic agents, and provided a better understanding of myeloma bone disease. The use of pharmacogenomic strategies in myeloma is thus already changing medical practice.

Myeloma cells (5TMM) and their interactions with the marrow microenvironment

Myeloma is a deadly B-cell neoplasm, characterized by the monoclonal proliferation of plasma cells, the development of osteolytic lesions, and the induction of angiogenesis. Myeloma cells are predominantly localized in the marrow where they receive the appropriate survival and proliferation signals. To reach or spread over the marrow, the myeloma cells need to migrate from the vascular to the extravascular compartment of the marrow. A process called "homing". In this review, the steps of the homing scheme, analyzed in the 5TMM model, will be described. These murine models originated from spontaneously developed myeloma in elderly mice and have since been propagated by intravenous injection of myeloma cells into young syngeneic mice. These models resemble the human condition closely. The different studies reported here demonstrate that adhesion of 5TMM cells to marrow endothelial cells is partially mediated by CD44v10 and to stromal cells by CD44v6. The 5TMM cells migrate to the marrow through the effects of MCP-1, laminin-1, and IGF-1. Once past the marrow endothelium, they invade the extravascular compartment of the marrow by secreting MMP-9 and uPA. When they have settled in the marrow, they become susceptible to the effects of IGF-1, which stimulates the cells to proliferate and produce VEGF. Furthermore, studies targeting the marrow with inhibitors will be highlighted. These studies show that the 5TMM models are useful for unraveling basic biological processes and for identifying new therapeutic targets.

Characterization of oncogene dysregulation in multiple myeloma by combined FISH and DNA microarray analyses

Chromosomal translocations involving the immunoglobulin heavy chain (IGH) locus and various partner loci frequently are associated with multiple myeloma (MM). We investigated the expression profiles of the FGFR3/MMSET, CCND1, CCND3, MAF, and MAFB genes, which are involved in t(4;14)(p16.3;q32), t(11;14)(q13;q32), t(6;14)(p21;q32), t(14;16)(q32;q23), and t(14;20)(q32;q12), respectively, in purified plasma cell populations from 39 MMs and six plasma cell leukemias (PCL) by DNA microarray analysis and compared the results with the presence of translocations as assessed by dual-color FISH or RT-PCR. A t(4;14) was found in 6 MMs, t(11;14) in 9 MMs and 1 PCL, t(6;14) in 1 MM, t(14;16) in 2 MMs and 1 PCL, and t(14;20) in 1 PCL. In all cases, the translocations were associated with the spiked expression of target genes. Furthermore, gene expression profiling enabled the identification of putative translocations causing dysregulation of CCND1 (1 MM and 1 PCL) and MAFB (1 MM and 1 PCL) without any apparent involvement of immunoglobulin loci. Notably, all of the translocations were mutually exclusive. Markedly increased MMSET expression was found in 1 MM showing associated FGFR3 and MMSET signals on an unidentified chromosome. Our data suggest the importance of using combined molecular cytogenetic and gene expression approaches to detect genetic aberrations in MM.

A neurotrophin axis in myeloma: TrkB and BDNF promote tumor-cell survival

Multiple myeloma (MM) is a B-cell neoplasm that is characterized by the clonal expansion of malignant plasma cells and is frequently associated with chromosomal translocations placing an oncogene under the control of the immunoglobulin heavy chain enhancer. Despite these pathogenic translocations, MM cells remain dependent on external cues for survival. We present evidence that brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of growth factors, and its high-affinity receptor, tropomyosin receptor kinase B (TrkB), contribute to these survival cues. MM cells express TrkB, and respond to BDNF by activating mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase-a PI3K target (PI3K/Akt) signaling cascades. Addition of BDNF protects human MM cell lines (HMCLs) from apoptosis induced by dexamethasone or bortezomib and prolongs the survival of primary MM cells cultured alone or with human bone marrow (BM) stroma. As BDNF and TrkB are expressed by osteoblasts, stromal cells, and endothelial cells within the BM microenvironment, a BDNF-TrkB axis may be critical to the interactions of MM with bone and stroma that contribute to MM tumor progression. Finally, BDNF is expressed by malignant plasma cells isolated from a subset of patients with MM, as well as by most HMCLs, suggesting a potential role for this neurotrophin axis in autocrine as well as paracrine support of MM.

Primary extramedullary plasmacytoma and multiple myeloma: phenotypic differences revealed by immunohistochemical analysis

Primary extramedullary plasmacytomas are infrequent, typically solitary, plasma cell neoplasms that generally pursue an indolent clinical course but may, rarely, convert to multiple myeloma. Phenotypic differences between these two entities are not well defined. Twenty-eight cases of primary extramedullary plasmacytoma and 26 cases of both medullary (n = 17) and extramedullary (n = 9) multiple myeloma were analysed for the expression of proteins known to play a role in the biology of multiple myeloma. Immunohistochemistry was performed on paraffin wax sections using antibodies against cyclin D1, Bcl-2, Bcl-xL, p27, p21, p53, MIB1, CD20, and CD56. Twenty-three extramedullary plasmacytomas were localized in the upper aerodigestive tract, four in the lymph nodes, and one in the testis. There was a strong male predominance (M : F = 6 : 1). None of the patients died from the disease or progressed to multiple myeloma (mean follow-up 50 months). Nine patients developed local relapse and one patient's tumour evolved into a B-cell non-Hodgkin's lymphoma. In contrast to both intra- and extra-medullary multiple myeloma, extramedullary plasmacytoma showed absence of cyclin D1 (p < 0.001) and infrequent expression of CD56 (p < 0.001). Furthermore, extramedullary plasmacytomas were characterized by weaker staining for Bcl-2 protein and rare overexpression of p21 and p53. In comparison to extramedullary multiple myeloma, extramedullary plasmacytoma showed a more mature morphology and lower proliferation indices (p = 0.008). There was no association between the phenotypic parameters investigated and clinical outcome in extramedullary plasmacytoma. In summary, extramedullary plasmacytoma and multiple myeloma show significant immunophenotypic differences, some of which may be of both diagnostic utility and biological relevance.

Delineation of distinct subgroups of multiple myeloma and a model for clonal evolution based on interphase cytogenetics

To delineate multiple myeloma (MM) subgroups and their clonal evolution, we analyzed 81 newly diagnosed patients by interphase fluorescence in situ hybridization using a comprehensive probe set for 10 chromosomes and two IGH rearrangements. A median of 5 probes per patient displayed aberrant signal numbers (range, 1-10). Additional copies most frequently found were for 15q22, 19q13, 9q34, 11q23, and 1q21. Losses commonly observed were of 13q14.3, 17p13, and 22q11. Predominance of gain or loss was quantified by a copy number score (CS) for each patient. Two peaks (CS = +3 and CS = 0) were found by plotting patient copy number scores over CS values corresponding to hyperdiploid and nonhyperdiploid MM. Cluster analysis revealed four major branches: (i) gain of 9q, 15q, 19q, and/or 11q; (ii) deletion of 13q and t(4;14); (iii) t(11;14); and (iv) gain of 1q. Statistical modeling of an oncogenetic tree indicated that early independent events were gain of 15q/9q and/or 11q, t(11;14); deletion of 13q followed by t(4;14); and gain of 1q. Aberrations of 17p13, 22q11, 8p12, and 6q21 were found as subsequent events. MM with gain of 1q was delineated as a subentity with significantly higher beta-2-microglobulin and lower hemoglobin levels, indicating a poor prognosis. From our results, we propose a model of MM for clonal evolution.

Combination of the mTOR inhibitor rapamycin and CC-5013 has synergistic activity in multiple myeloma

Previous studies have demonstrated the in vitro and in vivo activity of CC-5013 (Revlimid), an immunomodulatory analog (IMiD) of thalidomide, in multiple myeloma (MM). In the present study, we have examined the anti-MM activity of rapamycin (Rapamune), a specific mTOR inhibitor, combined with CC-5013. Based on the Chou-Talalay method, combination indices of less than 1 were obtained for all dose ranges of CC-5013 when combined with rapamycin, suggesting strong synergism. Importantly, this combination was able to overcome drug resistance when tested against MM cell lines resistant to conventional chemotherapy. Moreover, the combination, but not rapamycin alone, was able to overcome the growth advantage conferred on MM cells by interleukin-6 (IL-6), insulin-like growth factor-1 (IGF-1), or adherence to bone marrow stromal cells (BMSCs). Combining rapamycin and CC-5013 induced apoptosis of MM cells. Differential signaling cascades, including the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3′-kinase/Akt kinase (PI3K/Akt) pathways, were targeted by these drugs individually and in combination, suggesting the molecular mechanism by which they interfere with MM growth and survival. These studies, therefore, provide the framework for clinical evaluation of mTOR inhibitors combined with IMiDs to improve patient outcome in MM.

Both IGH translocations and chromosome 13q deletions are early events in monoclonal gammopathy of undetermined significance and do not evolve during transition to multiple myeloma

Molecular and genetic events associated with the transition from monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM) are still poorly characterized. We investigated serial bone marrow specimens from 11 patients with MGUS who eventually progressed to MM (MM post-MGUS) by interphase fluorescence in situ hybridization for immunoglobulin heavy-chain gene (IgH) translocations and chromosome 13q deletions (del(13q)). In nine patients, IgH translocations were present both in MGUS and MM post-MGUS plasma cells, including three t(11;14)(q13;q32) and one t(4;14)(p16;q32), which was observed already 92 months prior to MM. Similarly, all five MM patients with del(13q) had this aberration already at the MGUS stage. Two patients without IgH translocation and del(13q) had chromosomal gains suggesting hyperdiploidy, but IgH translocations and/or del(13q) did not emerge at MM post-MGUS. IgH translocations and del(13q) are early genetic events in monoclonal gammopathies, suggesting that additional events are required for the transition from stable MGUS to progressive MM.

Epigenetic silencing of the human nucleotide excision repair gene, hHR23B, in interleukin-6-responsive multiple myeloma KAS-6/1 cells

During tumorigenesis, selective proliferative advantage in certain cell subsets is associated with accumulation of multiple genetic alterations. For instance, multiple myeloma is characterized by frequent karyotypic instability at the earliest stage, progressing to extreme genetic abnormalities as the disease progresses. These successive genetic alterations can be attributed, in part, to defects in DNA repair pathways, perhaps based on epigenetic gene silencing of proteins involved in DNA damage repair. Here we report epigenetic hypermethylation of the hHR23B gene, a key component of the nucleotide excision repair in response to DNA damage, in interleukin-6 (IL-6)-responsive myeloma KAS-6/1 cells. This hypermethylation was significantly abated by Zebularine, a potent demethylating agent, with a consequent increase in the hHR23B mRNA level. Subsequent removal of this drug and supplementation with IL-6 in the culture medium re-established DNA hypermethylation of the hHR23B gene and silencing of mRNA expression levels. The inclination of DNA to be remethylated, at least within the hHR23B gene promoter region, reflects an epigenetic driving force by the cytogenetic/tumorigenic status of KAS-6/1 myeloma. The IL-6 response of KAS-6/1 myeloma also raises a question of whether the proneoplastic growth factor, such as IL-6, supports the epigenetic silencing of important DNA repair genes via promoter hypermethylation during the development of multiple myeloma.

Prognostic significance of vascular endothelial growth factor immunoexpression in the context of adverse standard prognostic factors in multiple myeloma

OBJECTIVES

Vascular endothelial growth factor (VEGF) acts in several steps of multiple myeloma (MM) pathogenesis and it is an important mediator of tumor angiogenesis. The aim of this study was to examine the prognostic significance of VEGF immunoexpression in the context of standard prognostic factors present in a cohort of advanced MM patients.

METHODS

Fifty untreated MM patients were enrolled from May 2000 to December 2002. Bone marrow sections were subjected to morphologic assessment and immunohistochemical studies with antibodies against CD34 and VEGF. Angiogenesis was measured by microvessel density (MVD) and stratified into high (MVD > or = 20) and low angiogenesis status (MVD < 20). VEGF immunoreactivity was examined on the basis of intensity and percentage of positive plasma cells (PC).

RESULTS

Ninety-four percent of patients presented advanced disease at diagnosis. Median PC marrow infiltration was 80%. Twelve percent of patients presented plasmablastic morphology. Low angiogenesis was present in 27% of patients, while high angiogenesis was present in 73%. Twenty-nine percent of patients had VEGF < 10% and 71% had VEGF > or = 10%. Weak-intensity VEGF was observed in 34% of cases, while 37% had moderate/strong VEGF intensity. Although VEGF had prognostic impact on overall survival (OS) and event-free survival (EFS) in univariate analysis, multivariate analysis identified only plasmablastic morphology and elevated serum lactate dehydrogenase (LDH) level as independent prognostic factors to predict OS (P = 0.04 and P = 0.02, respectively). With regard to EFS, although VEGF showed statistical trend to influence survival (P = 0.08), the parameters of independent prognostic value were also plasmablastic morphology (P = 0.01) and elevated LDH level (P = 0.01).

CONCLUSION

Our findings underline the frequent expression of VEGF in advanced-stage MM and the greater prognostic information of simple and readily available factors, namely plasmablastic morphology and elevated LDH. Moreover, despite the absence of prognostic importance in multivariate analysis, VEGF and its receptors remain promising therapeutic targets in MM.

The imbalance between Bim and Mcl-1 expression controls the survival of human myeloma cells

Multiple myeloma is a fatal B cell malignancy characterized by the accumulation of plasma cells within the bone marrow. IL-6 is a major survival factor for myeloma cells. Bcl-2 protein family regulates pathways to apoptosis that are activated upon growth factor deprivation. Pro-apoptotic proteins that have only a single Bcl-2 homology domain, BH3-only, are potent inducers of apoptosis. In myeloma cells, Mcl-1 has been shown to be a major anti-apoptotic protein that appears to regulate cell survival through the JAK/STAT pathway. In this study, we examined the regulation of the BH3-only protein Bim and its interaction with Mcl-1. The three major Bim isoforms are expressed in myeloma cells and are negatively regulated by IL-6. Blockade of IL-6 signaling induces an up-regulation of Bim concomitant to Mcl-1 down-regulation. Of major interest, Bim is found strongly associated with Mcl-1 in viable myeloma cells while this interaction is disrupted under apoptosis induction. Of note, while Bim is also found strongly associated to Bcl-2, this interaction is not changed under apoptosis induction. Thus, in myeloma cells, Mcl-1 neutralizes Bim through complex formation and therefore prevents apoptosis. Under apoptosis induction, the disappearance of Mcl-1 allows Bim to exercise its pro-apoptotic function and to activate Bax.

Clinical significance of circulating endothelial adhesion molecules (sE-selectin and sICAM) in untreated multiple myeloma patients

BACKGROUND

The expression of adhesion molecules is important for the interaction of myeloma cells with the bone marrow microenvironment. In the current study, serum soluble adhesion molecules (sICAM-1 and sE-selectin) were measured in untreated multiple myeloma (MM) patients in relation with other markers of disease activity.

MATERIALS AND METHODS

The study group consisted of 67 patients with MM (classified according to the Durie-Salmon classification) and 15 controls. Interleukin-6 (IL-6), sICAM-1 and sE-selectin concentrations were determined by enzyme-linked immunosorbent assay (ELISA). In addition, the monoclonal protein, erythrocyte sedimentation rate (ESR) and hemoglobin (Hb) concentration were also determined.

RESULTS

Serum sICAM-1 level increased significantly at advanced stages of MM and was higher in comparison to controls (p<0.01). sE-selectin increased significantly with advancing stage of the disease, but did not differ from controls. IL-6, ESR and M-component were significantly higher and Hb concentrations lower with advancing stage of disease. There was a positive correlation of IL-6 with sICAM-1 and sE-selectin.

CONCLUSIONS

We conclude that serum sICAM-1 differs in multiple myeloma patients from normals and together with sE-selectin increase in parallel to increasing stage of disease, which may reflect a dysregulation and possible involvement of these adhesion molecules in myeloma progression.

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.

Intravital microscopy: visualizing immunity in context

Recent advances in photonics, particularly multi-photon microscopy (MPM) and new molecular and genetic tools are empowering immunologists to answer longstanding unresolved questions in living animals. Using intravital microscopy (IVM) investigators are dissecting the cellular and molecular underpinnings controlling immune cell motility and interactions in tissues. Recent IVM work showed that T cell responses to antigen in lymph nodes are different from those observed in vitro and appear dictated by factors uniquely relevant to intact organs. Other IVM models, particularly in the bone marrow, reveal how different anatomic contexts regulate leukocyte development, immunity, and inflammation. This article will discuss the current state of the field and outline how IVM can generate new discoveries and serve as a "reality check" for areas of research that were formerly the exclusive domain of in vitro experimentation.

New treatment strategies for multiple myeloma

Multiple myeloma remains an incurable disease despite aggressive, high-dose therapy and intensive supportive care. Newer therapies with good safety profiles are needed for patients with multiple myeloma to improve the quality of responses and prolong survival. Novel treatment strategies for multiple myeloma include replacing conventional doxorubicin with pegylated liposomal doxorubicin and reducing the dexamethasone dose (DVd) in the widely accepted VAD (vincristine, conventional doxorubicin, dexamethasone) regimen to improve the safety profile. Because of its antiangiogenic and immunomodulatory effects, thalidomide has also been explored for use in the treatment of multiple myeloma and has demonstrated increased response rates when used in combination with dexamethasone. These findings subsequently led to the evaluation of the role of thalidomide in combination with pegylated liposomal doxorubicin, vincristine, and reduced-dose dexamethasone (the DVd-T regimen). This regimen was associated with response rates greater than 80% in patients with both newly diagnosed and relapsed/refractory multiple myeloma. Future applications of this and similar regimens for the treatment of multiple myeloma are currently being explored.

Multiple myeloma involving central nervous system: high frequency of chromosome 17p13.1 (p53) deletions

Central nervous system (CNS) involvement is an unusual manifestation in multiple myeloma (MM). The molecular basis of CNS myeloma is poorly understood. MM is characterized by translocations involving the immunoglobulin heavy chain (IgH) locus and frequent 13q deletions. Alterations of p53 or c-myc in MM may represent secondary changes associated with disease progression. We investigated nine patients with CNS MM using interphase fluorescence in situ hybridization (FISH) combined with immunofluorescence detection of the cytoplasmic light chain (cIg-FISH) for the presence of above genomic aberrations. Of nine patients studied, eight cases had hemizygous p53 deletion and 4 had 13q deletions. Of the patients with 13q deletions, two had IgH translocations, one involving 4p16.3 (FGFR3), the other involving 16q23 (c-maf). The high incidence of p53 deletions detected by cIg-FISH in CNS myeloma may be a marker for chromosomal instability, and may be associated with metastatic features of myeloma cells.

MCL-1 expression in B-cell non-Hodgkin’s lymphomas

B-cell non-Hodgkin's lymphomas are known to express BCL-2 family proteins, of which the myeloid cell leukemia-1 (MCL-1) protein is a member. MCL-1 is involved in viability and immortalization of normal and neoplastic B cells, and expression is regulated transcriptionally and posttranscriptionally, resulting in an anti-apoptotic (full length) or a pro-apoptotic (short isoform) gene product. In this study, we assessed 151 B-cell lymphomas for MCL-1 expression and analyzed for expression of the full-length and short isoforms of MCL-1 in B-cell lymphoma cell lines. By using immunohistochemistry, a subset of neoplasms in 9 lymphoma types studied expressed MCL-1, but expression was more frequent and intense in high-grade (43 of 49, 88%) compared with low-grade (34 of 92, 37%) lymphomas (P < 0.0001). In follicular lymphomas, MCL-1 expression positively correlated with increasing grade; 1 (14%) of eight grade 1, 7 (70%) of ten grade 2, and all 9 (100%) grade 3 were positive (P < 0.0008). All plasma cell myeloma cases assessed were also MCL-1 positive. By using Western blot analysis, 6 of 7 high-grade B-cell lymphoma cell lines showed predominant expression of full-length MCL-1, compared with no or weak expression of the short isoform. One myeloma and 1 of 2 mantle cell lymphoma cell lines also tested showed only full-length isoform expression. Our data suggest that MCL-1 is frequently expressed in high-grade B-cell lymphomas and plasma cell myeloma, most likely in its full-length isoform that is an active anti-apoptotic gene product. MCL-1 expression also correlates with grade and may contribute to transformation in follicular lymphomas.

Possible roles for activating RAS mutations in the MGUS to MM transition and in the intramedullary to extramedullary transition in some plasma cell tumors

To assess a possible role in tumor progression, the occurrence and type of K- and N-RAS mutations were determined in purified tumor cells, including samples from patients with premalignant monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM), and extramedullary plasma cell (PC) tumors (ExPCTs). Immunophenotypic aberrant PCs were flow sorted from 20 MGUS, 58 MM, and 13 ExPCT patients. One RAS mutation was identified in 20 MGUS tumors (5%), in contrast to a much higher prevalence of RAS mutations in all stages of MM (about 31%). Further, oncogene analyses showed that RAS mutations are not evenly distributed among different molecular subclasses of MM, with the prevalence being increased in MM-expressing cyclin D1 (P = .015) and decreased in MM with t(4;14) (P = .055). We conclude that RAS mutations often provide a genetic marker if not a causal event in the evolution of MGUS to MM. Surprisingly, RAS mutations were absent in bone marrow tumor cells from all patients with ExPCT, a result significantly different from intramedullary MM (P = .001). From 3 of 6 patients with paired intramedullary and extramedullary PCs and identical immunoglobulin heavy chain gene (IgH) sequences, RAS mutations were identified only in extramedullary PCs, suggesting a role for RAS mutations in the transition from intramedullary to extramedullary tumor.

Clinical implications of advanced molecular cytogenetics in cancer

The field of cytogenetics has already entered the molecular era and a rapid expansion of its contribution is seen in genomic disease management. Among the evolving advanced molecular techniques, with an impeccable balance of high specificity, sensitivity and assay rapidity, fluorescence in situ hybridization has made its home in routine clinical laboratory. Today, its clinical application is vivid in every phase of disease management of a number of malignancies. The rapid growth in the knowledge of specific associations between distinct chromosomal abnormalities and different types of cancers will necessitate simultaneous detection of multiple abnormalities using multicolor/multiplex fluorescence in situ hybridization tests more often in the near future. Also, as the human genome sequence is ascertained, genome-wide screening with microarray technology will gain eminence in the clinical scenario, yield better solutions and bring the concept of personalized medicine in cancer closer to reality than ever before.

Combined disruption of both the MEK/ERK and the IL-6R/STAT3 pathways is required to induce apoptosis of multiple myeloma cells in the presence of bone marrow stromal cells

The interleukin-6 receptor (IL-6R)/signal transducer and activator of transcription 3 (STAT3) pathway contributes to the pathogenesis of multiple myeloma (MM) and protects MM cells from apoptosis. However, MM cells survive the IL-6R blockade if they are cocultured with bone marrow stromal cells (BMSCs), suggesting that the BM microenvironment stimulates IL-6-independent pathways that exert a pro-survival effect. The goal of this study was to investigate the underlying mechanism. Detailed pathway analysis revealed that BMSCs stimulate STAT3 via the IL-6R, and mitogen-activated protein (MAP) kinases via IL-6R-independent mechanisms. Abolition of MEK1,2 activity with PD98059, or ERK1,2 small interfering RNA knockdown, was insufficient to induce apoptosis. However, the combined disruption of the IL-6R/STAT3 and MEK1,2/ERK1,2 pathways led to strong induction of apoptosis even in the presence of BMSCs. This effect was observed with MM cell lines and with primary MM cells, suggesting that the BMSC-induced activation of MEK1,2/ERK1,2 renders MM cells IL-6R/STAT3 independent. Therefore, in the presence of cells from the BM micro-environment, combined targeting of different (and independently activated) pathways is required to efficiently induce apoptosis of MM cells. This might have direct implications for the development of future therapeutic strategies for MM.

Overexpression of the NOTCH ligand JAG2 in malignant plasma cells from multiple myeloma patients and cell lines

The NOTCH ligand, JAG2, was found to be overexpressed in malignant plasma cells from multiple myeloma (MM) patients and cell lines but not in nonmalignant plasma cells from tonsils, bone marrow from healthy individuals, or patients with other malignancies. In addition, JAG2 overexpression was detected in 5 of 5 patients with monoclonal gammopathy of undetermined significance (MGUS), an early phase of myeloma disease progression. This overexpression appears to be a consequence of hypomethylation of the JAG2 promoter in malignant plasma cells. An in vitro coculture assay was used to demonstrate that JAG2 induced the secretion of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and insulin-like growth factor-1 (IGF-1) in stromal cells. Further, the induction of IL-6 secretion was blocked in vitro by interference with anti-Notch-1 monoclonal antibodies raised against the binding sequence of Notch-1 with JAG2. Taken together, these results indicate that JAG2 overexpression may be an early event in the pathogenesis of multiple myeloma involving IL-6 production.

Induction of CD28 on the new myeloma cell line MOLP-8 with t(11;14)(q13;q32) expressing δ/λ type immunoglobulin

The novel multiple myeloma (MM) cell line MOLP-8 carrying the t(11;14) (q13;q32) was established from the peripheral blood of a 52-year-old Japanese male patient with Bence-Jones delta/lambda type MM (stage IIIA with hyperammonemia). The growth of MOLP-8 cells is constitutively independent of exogenous growth factors or feeder cells. MOLP-8 cells grow mainly as free floating single cells and slightly adherent on the bottom of the plastic culture flask. Wright-Giemsa-stained MOLP-8 cells show the typical plasma cell morphology with abundant cytoplasm, heterogeneous cell size and one to three nuclei. The immunoprofile of MOLP-8 corresponds to that seen typically in primary MM cells: positive for cytoplasmic immunoglobulin (Ig) delta/lambda chains, CD10, CD29, CD38, CD40, CD44, CD49b, CD49d, CD54, CD56, CD58, CD71, CD138 and PCA-1; the cells were negative for surface Igs and various other B-cell, T-cell and myelomonocyte-associated immunomarkers. CD28 became positive after co-culture of MOLP-8 cells with bone marrow adherent stromal (BST) feeder cells for a week. About 30% of MOLP-8 cells adhered strongly to the BST cells, but the cellular adhesion was clearly inhibited by addition of either anti-CD29 or anti-CD106 monoclonal antibody, suggesting a specific cellular adhesion through alpha4beta1-integrin-VCAM-1 interaction. The novel MOLP-8 cell line together with the present myeloma cell lines will present useful model systems in the investigation of the biology of MM.