Beyond the cell: novel noncellular immunotherapy approaches to multiple myeloma

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Prognostic implications of tumor cell DNA and RNA content in multiple myeloma

Flow cytometric studies of bone marrow DNA and RNA content were conducted in 71 previously untreated patients with multiple myeloma. There was a progressive increase in response rate with rising plasma cell RNA content. The DNA-derived ploidy level also affected chemotherapy sensitivity: only one of 11 patients with either hypodiploidy or biclonal DNA stemlines responded. DNA-RNA-defined marrow plasmacytosis was the only tumor mass-related variable adversely affecting remission induction. Survival was longer in patients with low tumor burden and favorable DNA features. The availability of objective and quantitative pretreatment variables associated with both initial response and survival should permit a risk-based selection of patients for novel treatment approaches.     

Autologous stem cell transplantation in elderly multiple myeloma patients over the age of 70 years

The feasibility and efficacy of autologous stem cell transplantation (auto-SCT) in patients aged > or = 70 years was analysed. Newly diagnosed (n = 34) and refractory multiple myeloma (n = 36) patients were studied. The median age was 72 years (range: 70-82.6). CD34+ cells were mobilized with chemotherapy and granulocyte colony-stimulating factor (G-CSF) (n = 35) or G-CSF alone (n = 35), yielding medians of 11.8 x 10(6) versus 8 x 10(6) cells/kg respectively (P = 0.007). Because of excessive mortality (16%) in the first 25 patients who received melphalan 200 mg/m2 (MEL-200), the dose was subsequently decreased to 140 mg/m2 (MEL-140). Median times to absolute neutrophil count (ANC) > 0.5 x 10(9)/l and to platelets > 20 x 10(9)/l were 11 and 13 d respectively. Thirty-one patients (44%) received tandem auto-SCT. Complete remission (CR) was 20% after the first SCT and 27% after tandem SCT. Median CR duration was 1.5 years and was significantly longer for patients with < or = 12 months of prior chemotherapy (2.6 versus 1.0 years, P = 0.0008). The 3-year event-free survival (EFS) and overall survival (OS) (+ standard error, SE) were projected at 20% + 9% and 31% + 10% respectively. Tandem SCTs positively affected EFS (4.0 versus 0.7 years; P = 0.003) and OS (4.0 versus 1.4 years; P = 0.02) compared with single auto-SCT. In conclusion, MEL-140 is less toxic and appears equally as efficacious as MEL-200 in elderly patients. The benefits of tandem SCT in this patient population need further evaluation in a randomized trial.     

Combined functional and molecular analysis of tumor cell signaling defines 2 distinct myeloma subgroups: Akt-dependent and Akt-independent multiple myeloma

Although the phosphatidylinositide 3-kinase (PI3K)/Akt pathway has been reported to contribute to the malignant growth of multiple myeloma (MM), the true relevance of Akt kinases for this disease is still unclear. In particular, functional analyses in primary tumor cells and genetic target validation experiments are missing. Here, we used combined functional and molecular analyses to determine the importance of Akt activity in a large panel of primary MM samples and in MM cell lines. Akt down-regulation with isoform-specific siRNA constructs or with an Akt1/2-specific pharmacologic inhibitor strongly induced apoptosis in approximately half of the primary MM samples analyzed. Sensitivity to Akt inhibition strongly correlated with the activation status of Akt as determined by immunohistochemistry, phospho-Akt-specific flow cytometry, and Western analysis. Additional blockade of the MAPK and the IL-6R/STAT3 pathways was often not sufficient to decrease the viability of MM cells resilient to Akt inhibition. Taken together, these experiments led to the identification of 2 myeloma subgroups: Akt-dependent and Akt-independent MM.     

HSP70 inhibition reverses cell adhesion mediated and acquired drug resistance in multiple myeloma

Heat shock proteins (HSPs) are a super family of highly conserved molecular chaperone proteins, which are induced in response to stress. HSP70 has been demonstrated to inhibit apoptosis induced by a number of chemotherapeutic agents. Previous investigations have suggested the development of drug resistance in multiple myeloma (MM) cells after adhesion to stroma. This study used MM cell lines and primary plasma cells to determine if HSP70 had a role in development of chemo resistance. Adhesion of MM cells to either bone marrow stromal cells or fibronectin (FN) enhanced HSP70 expression. Inhibition of the HSP70 expression decreased 8226 cell adhesion to stroma or FN and induced more apoptosis in FN-adhered 8226 cells than in suspension cultures at 24 h. Further, HSP70 inhibitors enhanced melphalan-induced apoptosis and reversed melphalan-induced cell adhesion-mediated drug resistance (CAM-DR) phenotype. In addition, compared to parental cells, KNK-437, a heat shock factor inhibitor caused more apoptosis in melphalan-resistant 8226/LR5 cells and sensitized them to melphalan. Primary CD138 positive cells showed high expression of HSPA4 mRNA, and KNK-437 caused apoptosis in these cells. In conclusion, our data suggest inhibition of HSP70, reduced adhesion and caused apoptosis of both acquired and de novo drug resistant MM cells.     

Phenotypic and functional analysis of B cell lines from patients with multiple myeloma

We characterized phenotypic and functional properties of B cell lines obtained from patients with multiple myeloma to determine how well they conform to particular stages of B cell differentiation. This information is a prerequisite for using such lines as tools for studying B cell growth and the regulation thereof. Two lines, GM1312 and GM1500, expressed B1 and Ia, determinants on early B cells, but expressed little, if any, T10, a determinant expressed on plasma cells. By contrast, B1 and Ia were poorly expressed on two other lines, GM2132 and U266. T10 was expressed on GM2132 but not on U266. Using a reverse hemolytic plaque assay, we also assessed the numbers of cells actively secreting immunoglobulin (IgSCs) in such cultures to provide a functional marker of B cell differentiation. We observed consistently higher numbers of IgSCs in cultures of GM2132 than in GM1500 and GM1312. These phenotypic and functional markers were stable over several months. The data suggest that such cell lines represent early (GM1312, GM1500) and later stages (GM2132, U266) of B cell differentiation, although all lines were derived from patients with multiple myeloma.     

Translocation of annexin Ⅰ from cellular membrane to the nuclear membrane in human esophageal squamous cell carcinoma

AIM: To investigate the alteration of the annexin I subcellular localization in esophageal squamous cell carcinoma (ESCC)and the correlation between the translocation and the tumorigenesis of ESCC.METHODS: The protein localization of annexin I was detected in both human ESCC tissues and cell line via the indirect immunofiuorescence strategy.RESULTS: In the normal esophageal epithelia the annexin I was mainly located on the plasma membrane and formed a consecutive typical trammels net. Annexin I protein also expressed dispersively in cytoplasm and the nuclei without specific localization on the nuclear membrane. In esophageal cancer annexin I decreased very sharply with scattered disappearance on the cellular membrane, however it translocated and highly expressed on the nuclear membrane,which was never found in normal esophageal epithelia. In cultured esophageal cancer cell line annexin I protein was also focused on the nuclear membrane, which was consistent with the result from esophageal cancer tissues.CONCLUSION: This observation suggests that the translocation of annexin I protein in ESCC may correlate with the tumorigenesis of the esophageal cancer.     

Circulating endothelial progenitor cells in multiple myeloma: implications and significance

Angiogenesis governs the progression of multiple myeloma (MM). Circulating endothelial cells (CECs) contribute to angiogenesis and comprise mature ECs and endothelial progenitor cells (EPCs). The present study sought to characterize CECs and their relation to disease activity and therapeutic response in 31 consecutive patients with MM. CECs, identified as CD34(+)/CD146(+)/CD105(+)/CD11b(-) cells, were 6-fold higher in patients compared to controls and correlated positively with serum M protein and beta(2)-microglobulin. Circulating EPCs displayed late colony formation/outgrowth and capillary-like network formation on matrigel; these processes were inhibited after effective thalidomide treatment. Co-expression of vascular endothelial growth factor receptor-2 (KDR) and CD133 characterized EPCs in MM, and KDR mRNA elevations correlated with M protein levels. In vitro exposure of ECs to thalidomide or its derivative CC-5013 inhibited gene expression of the receptors for transforming growth factor-beta and thrombin. Thus, elevated levels of CECs and EPCs covary with disease activity and response to thalidomide, underscoring the angiogenic aspect of MM and suggesting that angioblastlike EPCs are a pathogenic biomarker and a rational treatment target in MM. The results also highlight the anti-angiogenic properties of thalidomide and CC-5013 and further elucidate possible mechanisms of their effectiveness against MM. (Blood. 2005;105:3286-3294).     

Translocation of annexin I from cellular membrane to the nuclear membrane in human esophageal squamous cell carcinoma

AIM: To investigate the alteration of the annexin I subcellular localization in esophageal squamous cell carcinoma (ESCC) and the correlation between the translocation and the tumorigenesis of ESCC. METHODS: The protein localization of annexin I was detected in both human ESCC tissues and cell line via the indirect immunofluorescence strategy. RESULTS: In the normal esophageal epithelia the annexin I was mainly located on the plasma membrane and formed a consecutive typical trammels net. Annexin I protein also expressed dispersively in cytoplasm and the nuclei without specific localization on the nuclear membrane. In esophageal cancer annexin I decreased very sharply with scattered disappearance on the cellular membrane, however it translocated and highly expressed on the nuclear membrane, which was never found in normal esophageal epithelia. In cultured esophageal cancer cell line annexin I protein was also focused on the nuclear membrane, which was consistent with the result from esophageal cancer tissues. CONCLUSION: This observation suggests that the translocation of annexin I protein in ESCC may correlate with the tumorigenesis of the esophageal cancer.     

Tumour cell/dendritic cell fusions as a vaccination strategy for multiple myeloma

Multiple myeloma (MM) cells express certain tumour-associated antigens (TAAs) that could serve as targets for active-specific immunotherapy. The aim of the present study was to test the MM/dendritic cell (DC) fusion as a vaccination strategy. We fused MM cells with DC to generate fusion cells (FCs) and tested their antigen presenting cell (APC) function in mixed lymphocyte reactions and cytotoxicity assays. First, the HS Sultan and SK0-007 HAT sensitive human MM cell lines and DCs generated from peripheral blood of normal donors were fused in the presence of 50% polyethylene glycol to form FCs. Next, tumour cells freshly isolated from patients were similarly fused with autologous DCs to generate FCs. The FCs demonstrated a biphenotypic profile, confirmed both by flow-cytometry and dual immunofluorescence microscopy. These FCs induced MM-specific cytotoxicity. FCs, but not MM cells or DCs alone, were potent stimulators of autologous patient T cells. More importantly, FC-primed autologous peripheral blood mononuclear cells demonstrated major histocompatibility complex-restricted MM-specific cytolysis. These studies therefore demonstrated that MM/DC FC can trigger an autologous immune response to MM cells and formed the framework for a clinical trial currently underway.     

The selective adhesion molecule inhibitor Natalizumab decreases multiple myeloma cell growth in the bone marrow microenvironment: therapeutic implications

Recent advances regarding the introduction of anti-adhesion strategies as a novel therapeutic concept in oncology hold great promise. Here we evaluated the therapeutic potential of the new-in-class-molecule selective-adhesion-molecule (SAM) inhibitor Natalizumab, a recombinant humanized IgG4 monoclonal antibody, which binds integrin-α4, in multiple myeloma (MM). Natalizumab, but not a control antibody, inhibited adhesion of MM cells to non-cellular and cellular components of the microenvironment as well as disrupted the binding of already adherent MM cells. Consequently, Natalizumab blocked both the proliferative effect of MM-bone marrow (BM) stromal cell interaction on tumour cells, and vascular endothelial growth factor (VEGF)-induced angiogenesis in the BM milieu. Moreover, Natalizumab also blocked VEGF- and insulin-like growth factor 1 (IGF-1)-induced signalling sequelae triggering MM cell migration. In agreement with our in vitro results, Natalizumab inhibited tumour growth, VEGF secretion, and angiogenesis in a human severe combined immunodeficiency murine model of human MM in the human BM microenvironment. Importantly, Natalizumab not only blocked tumour cell adhesion, but also chemosensitized MM cells to bortezomib, in an in vitro therapeutically representative human MM-stroma cell co-culture system model. Our data therefore provide the rationale for the clinical evaluation of Natalizumab, preferably in combination with novel agents (e.g. bortezomib) to enhance MM cytotoxicity and improve patient outcome.     

Strategies to improve the outcome of stem cell transplantation in multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy with an average survival of 3 years with conventional therapy. Allogeneic hematopoietic cell transplantation (allo-HCT) may cure some patients, but has been associated with a very high transplantation-related mortality (TRM) of over 40%.(1) In contrast to allo-HCT, autologous hematopoietic cell transplantation (AHCT) has been much safer, with a TRM <3% in the 1990s. Therefore, in the last 15 years AHCT has become a common procedure for MM patients. The widespread use of AHCT has been associated with a median survival of 55-72 months,(2,3,4,5,6) and two large randomized trials have shown that AHCT is superior to conventional chemotherapy for the treatment of MM.(3,7) Approaches to improve the outcome of stem cell transplantation for MM patients include consideration of patient status, efficacy and toxicity of induction therapy, source of hematopoietic rescue, conditioning regimens, and maintenance therapy. Recent attempts to improve outcome include tandem AHCT, AHCT followed by RIC (reduced intensity conditioning) allo-HCT, and allo-HCT with T-cell depletion and subsequent donor-lymphocyte infusions (DLI), while novel therapies and improved supportive care may improve the overall survival (OS) of all MM patients with or without transplantation.     

Nuclear clusterin/XIP8, an x-ray-induced Ku70-binding protein that signals cell death

Clusterin [CLU, a.k.a. TRPM-2, SGP-2, or ionizing radiation (IR)-induced protein-8 (XIP8)] was implicated in apoptosis, tissue injury, and aging. Its function remains elusive. We reisolated CLU/XIP8 by yeast two-hybrid analyses using as bait the DNA double-strand break repair protein Ku70. We show that a delayed (2-3 days), low-dose (0.02-10 Gy) IR-inducible nuclear CLU/XIP8 protein coimmunoprecipitated and colocalized (by confocal microscopy) in vivo with Ku70/Ku80, a DNA damage sensor and key double-strand break repair protein, in human MCF-7:WS8 breast cancer cells. Overexpression of nuclear CLU/XIP8 or its minimal Ku70 binding domain (120 aa of CLU/XIP8 C terminus) in nonirradiated MCF-7:WS8 cells dramatically reduced cell growth and colony-forming ability concomitant with increased G(1) cell cycle checkpoint arrest and increased cell death. Enhanced expression and accumulation of nuclear CLU/XIP8-Ku70/Ku80 complexes appears to be an important cell death signal after IR exposure.     

Visualization of ribosome-recycling factor on the Escherichia coli 70S ribosome: functional implications

After the termination step of protein synthesis, a deacylated tRNA and mRNA remain associated with the ribosome. The ribosome-recycling factor (RRF), together with elongation factor G (EF-G), disassembles this posttermination complex into mRNA, tRNA, and the ribosome. We have obtained a three-dimensional cryo-electron microscopic map of a complex of the Escherichia coli 70S ribosome and RRF. We find that RRF interacts mainly with the segments of the large ribosomal subunit's (50S) rRNA helices that are involved in the formation of two central intersubunit bridges, B2a and B3. The binding of RRF induces considerable conformational changes in some of the functional domains of the ribosome. As compared to its binding position derived previously by hydroxyl radical probing study, we find that RRF binds further inside the intersubunit space of the ribosome such that the tip of its domain I is shifted (by approximately 13 A) toward protein L5 within the central protuberance of the 50S subunit, and domain II is oriented more toward the small ribosomal subunit (30S). Overlapping binding sites of RRF, EF-G, and the P-site tRNA suggest that the binding of EF-G would trigger the removal of deacylated tRNA from the P site by moving RRF toward the ribosomal E site, and subsequent removal of mRNA may be induced by a shift in the position of 16S rRNA helix 44, which harbors part of the mRNA.