International Myeloma Working Group molecular classification of multiple myeloma: spotlight review

Myeloma is a malignant proliferation of monoclonal plasma cells. Although morphologically similar, several subtypes of the disease have been identified at the genetic and molecular level. These genetic subtypes are associated with unique clinicopathological features and dissimilar outcome. At the top hierarchical level, myeloma can be divided into hyperdiploid and non-hyperdiploid subtypes. The latter is mainly composed of cases harboring IgH translocations, generally associated with more aggressive clinical features and shorter survival. The three main IgH translocations in myeloma are the t(11;14)(q13;q32), t(4;14)(p16;q32) and t(14;16)(q32;q23). Trisomies and a more indolent form of the disease characterize hyperdiploid myeloma. A number of genetic progression factors have been identified including deletions of chromosomes 13 and 17 and abnormalities of chromosome 1 (1p deletion and 1q amplification). Other key drivers of cell survival and proliferation have also been identified such as nuclear factor- B-activating mutations and other deregulation factors for the cyclin-dependent pathways regulators. Further understanding of the biological subtypes of the disease has come from the application of novel techniques such as gene expression profiling and array-based comparative genomic hybridization. The combination of data arising from these studies and that previously elucidated through other mechanisms allows for most myeloma cases to be classified under one of several genetic subtypes. This paper proposes a framework for the classification of myeloma subtypes and provides recommendations for genetic testing. This group proposes that genetic testing needs to be incorporated into daily clinical practice and also as an essential component of all ongoing and future clinical trials.

Genetic polymorphisms of EPHX1, Gsk3beta, TNFSF8 and myeloma cell DKK-1 expression linked to bone disease in myeloma

Bone disease in myeloma occurs as a result of complex interactions between myeloma cells and the bone marrow microenvironment. A custom-built DNA single nucleotide polymorphism (SNP) chip containing 3404 SNPs was used to test genomic DNA from myeloma patients classified by the extent of bone disease. Correlations identified with a Total Therapy 2 (TT2) (Arkansas) data set were validated with Eastern Cooperative Oncology Group (ECOG) and Southwest Oncology Group (SWOG) data sets. Univariate correlates with bone disease included: EPHX1, IGF1R, IL-4 and Gsk3beta. SNP signatures were linked to the number of bone lesions, log(2) DKK-1 myeloma cell expression levels and patient survival. Using stepwise multivariate regression analysis, the following SNPs: EPHX1 (P=0.0026); log(2) DKK-1 expression (P=0.0046); serum lactic dehydrogenase (LDH) (P=0.0074); Gsk3beta (P=0.02) and TNFSF8 (P=0.04) were linked to bone disease. This assessment of genetic polymorphisms identifies SNPs with both potential biological relevance and utility in prognostic models of myeloma bone disease.

Clinical and biological implication of defective p53 pathway in multiple myeloma (MM)

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Background: The p53 tumor suppressor is commonly inactivated by mutations. Even in tumors without mutations, there are defects in the response to p53 activation. In MM, the prognostic significance of p53 mutation is unknown, while there has been no systematic study of p53 function. We seek to address these issues in this study. Methods: p53 mutation was studied by conformation sensitive gel electrophoresis with primers encompassing exons 1 to 10 followed by sequencing of DNA fragments with altered electrophoretic pattern in newly diagnosed MM patients entered into ECOG E9486 trial where patients were randomized to receive variations of melphalan-based conventional chemotherapy (VBMCP). Fisher’s exact tests were used to compare variables between patients. Kaplan-Meier survival curves were compared using the log-rank test. To investigate p53 function, we analyzed the expression of p53, and 3 of its transcriptional targets, APAF1, p21 and MDM2, in a separate cohort of 15 normal plasma cells (PC), 14 MGUS, 13 smoldering myeloma (SMM) and 101 MM (73 new and 28 relapsed) from the Mayo Clinic who had gene expression profiling performed on the Affymetrix U133A chip (Santa Clara, Ca). Results: Two hundred and sixty-eight patients had enough materials for study and were included in the analysis. The prevalence of p53 mutation was 3% (n = 9). Five of the 9 patients (56%, p = 0.001) with mutations also had p53 deletion (studied by fluorescent in-situ hybridization) resulting in bi-allelic loss of p53. Soft tissue plasmacytomas (37% v 7%, p = 0.018), and among the common translocations, t(4;14) and t(14;16) (50% v 18%) were more common in patients with p53 mutations. Despite similar response to treatment, those with p53 mutation had very short OS (16.7 v 41.4 months, p < 0.001). There was induction of p53 expression in MGUS and SMM with concurrent induction of APAF1, p21 and MDM2 whereas loss of this pattern was frequent in MM (45% in new MM and 60% in relapse MM compared to 15% in MGUS/SMM (p = 0.03)). Conclusions: p53 mutations are relatively rare in newly diagnosed MM patients but portend a short survival. However, functional abnormalities of p53 are prevalent and may be important in progression from MGUS/SMM to MM.

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Distinct IL-6 signal transduction leads to growth arrest and death in B cells or growth promotion and cell survival in myeloma cells

In B cell development, interleukin-6 (IL-6) induces terminal maturation of B lymphocytes into antibody producing plasma cells. Terminal differentiated B cells cell cycle arrest and death follows. In contrast, IL-6 acts as a growth factor for malignant myeloma plasma cells and in some cases protects them from therapeutic treatment. In this study, we examined two cell lines that show different responses to IL-6. Lymphoblastoid CESS cells respond to IL-6 by terminally differentiating into antibody producing plasma cells, cell cycle arrest, and undergo cell death. Continuous addition of IL-6 to these cells induces transient activation of STAT3, SHP-2 phosphorylation, and does not alter bcl-X(L) and c-myc expression. In contrast, the myeloma line ANBL6 proliferates when stimulated with IL-6 and this correlates with prolonged STAT3 activation and up-regulation of bcl-X(L) and c-myc. Interestingly, gp130-associated SHP-2 phosphorylation was detected in the IL-6-induced CESS cells but not myeloma cell lines. The data show a very distinct IL-6 signal transduction and kinetics in these cell lines and the distinct molecular events correlate closely to the cell fate of the lymphoblast and myeloma cell lines.

Blood levels of immune cells predict survival in myeloma patients: results of an Eastern Cooperative Oncology Group phase 3 trial for newly diagnosed multiple myeloma patients

Previously, it was reported that patients with multiple myeloma (MM) who have higher baseline levels of blood CD4(+) or CD19(+) cells have longer survival. This article extends the analysis of immune cell levels and survival in a large cohort (N = 504) of patients with MM entered on Eastern Cooperative Oncology Group (ECOG) phase 3 trial (9486). Newly diagnosed patients with MM received 2 cycles of vincristine, bischloroethylnitrosourea, melphalan, cytoxan, prednisone (VBMCP) and were treated on one of 3 randomized arms: VBMCP with either interferon or high-dose cyclophosphamide, or VBMCP alone. Blood immune cell levels were studied at trial entry (baseline), after 2 cycles of chemotherapy, after 2 years of therapy, and at relapse. Baseline CD3(+), CD4(+), CD8(+), CD19(+), and CD4(+) subset cell levels were all positively associated with survival (P =.0087 to P <.0001). A multivariate analysis incorporating CD4(+) and CD19(+) cell levels defined 3 separate groups of patients with MM to survival outcome. Higher CD19(+) blood levels were positively associated with MM-patient survival at entry to the study, at year 2, and at relapse (P <.0001 at all 3 timepoints). Patients with MM had evidence of immune cell reconstitution after 2 years of therapy, but the rate and extent of recovery was greater for CD8(+), which was greater than CD4(+), which was greater than CD19(+). This latter data affirms the positive relationship between the quantitative status of the blood immune system in MM and survival. In addition, the importance of the CD19(+) blood cells to survival is evident throughout the course of MM. Therapeutic efforts to maintain an intact immune system may be crucial in maximizing chemotherapeutic and/or immunotherapy efforts in this disease.

Deletions of chromosome 13 in multiple myeloma identified by interphase FISH usually denote large deletions of the q arm or monosomy

Deletions of the long arm of chromosome 13 (13q-) are observed in patients with multiple myeloma (MM), are rarely observed in the monoclonal gammopathy of undetermined significance (MGUS) and have been associated with a worsened prognosis in MM. However, no minimally deleted region in the 13q arm has been defined at 13q, and consequently no tumor suppressor genes have yet been identified that are important for disease pathogenesis. We attempted to characterize these chromosome 13q deletions at the molecular cytogenetic level. We studied 351 newly diagnosed patients, entered into the E9486/E9487 clinical study of the Eastern Cooperative Oncology Group. Fluorescent in situ hybridization (FISH) combined with immune fluorescent detection (cIg-FISH) of clonal plasma cells (PC) and cytomorphology were used to analyze interphase, bone marrow (BM) cell, cytospin slides. We simultaneously used DNA probes for the following locus specific probes (LSI); LSI 13 (Rb) and D13S319, which hybridize to 13q14. We subsequently studied distal deletions using the D13S25 probe (13q14.3) and a subtelomeric probe (13qSTP) for the 13q-arm (D13S327) in 40 cases with documented LSI 13 (Rb)/D13S319 deletion and 40 without deletion of these loci. Of 325 evaluable patients, we found 13q deletions in 176 (54%) using LSI 13 (Rb) and D13S319 probes. Of 40 patients with LSI 13 (Rb)/D13S319 deletions, 34 (85%) had coexistent deletion of both D13S25/13qSTP. These results indicate that chromosome 13 deletions in MM involve loss of most if not all of the 13q arm perhaps even indicating monosomy. In six cases the 13qSTP signal was conserved, but D13S25 was lost indicating large interstitial deletions involving 13q14. In 39 of the 40 cases without LSI 13 (Rb)/D13S319 deletions, the normal pattern of two pairs of signals was observed for D13S25/13qSTP. Deletions involving 13q14 are very common in MM as detected by cIg-FISH. These deletions appear to predominantly involve loss of large segments of the 13q arm or monosomy 13, and only occasionally represent an interstitial deletion.

The bone marrow stromal microenvironment influences myeloma therapeutic response in vitro

The bone marrow microenvironment supports growth and differentiation of normal hematopoietic cells and can contribute to malignant growth. Since myeloma cells localize and accumulate in bone marrow, it is important to understand the influence of the bone marrow microenvironment not only on the growth of the malignant cells, but also on the therapeutic response of myeloma cells. Growth factors such as interleukin-6 (IL-6) produced by bone marrow stromal cells can protect myeloma cells from glucocorticoid-induced apoptosis. We examined the effect of myeloma cells-bone marrow stromal cells interaction in vitro on several therapeutic treatments. An interleukin-6-dependent myeloma cell line ANBL6 was used and treated with dexamethasone, doxorubicin, and melphalan in the presence of bone marrow stromal cells. Stromal cells were able to protect ANBL6 from dexamethasone, but significantly enhanced the effect of doxorubicin and melphalan. IL-6-induced bcl-XL and cyclin D2 expression in ANBL6 cells, but dexamethasone was able to suppress both bcl-XL and cyclin D2 expression in ANBL6. Doxorubicin and melphalan were able to suppress bcl-XL expression only in the presence of IL-6. We also looked at the effect of activating mutations of N-ras in myeloma cells interacting with stromal cells on therapeutic responses. Surprisingly, ANBL6 N-ras shows significant resistance to all drugs used. Notably, the presence of stromal cells did not alter ANBL6 Nras cells' drug resistance. These results suggest both the bone marrow microenvironment and genetic alterations of myeloma cells can independently impact on therapeutic responses.

Induced kappa receptor editing shows no allelic preference in a mouse pre-B cell line

B cell Ag receptor editing is a process that can change kappa antigen recognition specificity of a B cell receptor through secondary gene rearrangements on the same allele. In this study we used a model mouse pre-B cell line (38B9) to examine factors that might affect allelic targeting of secondary rearrangements of the kappa locus. We isolated clones that showed both productive and nonproductive rearrangements of one kappa allele, while retaining the other kappa allele in the germline configuration (kappa(+)/kappa degrees or kappa(-)/kappa degrees ). In the absence of any selective pressures, subsequent rearrangement of the germline alleles occurred at the same frequency as secondary rearrangement of the productive or nonproductive rearranged alleles. Because 38B9 cells lack Ig heavy chains, we stably expressed mu heavy chain protein in 38B9 cells to determine whether heavy-light pairing might affect allelic targeting of secondary kappa rearrangements. Although the expression of heavy chain was found to both pair with and stabilize kappa protein in these cells, it had no effect on preferential targeting Vkappa-Jkappa receptor editing compared with rearrangement of a germline allele. These studies suggest that in the absence of selection to eliminate autoreactive Vkappa-Jkappa genes, there is no allelic preference for secondary rearrangement events in 38B9 cells.

Heterogeneity in therapeutic response of genetically altered myeloma cell lines to interleukin 6, dexamethasone, doxorubicin, and melphalan

Because there is no known genetic abnormality common to all patients with myeloma, it is important to understand how genetic heterogeneity may lead to differences in signal transduction, cell cycle, and response to therapy. Model cell lines have been used to study the effect that mutations in p53 and ras can have on growth properties and responses of myeloma cells. The U266 cell line has a single mutant p53 allele. Stable expression of wild-type (wt) p53 in U266 cells results in a significant suppression of interleukin (IL)-6 gene expression and in the concomitant suppression of cell growth that could be restored by the addition of exogenous IL-6. Expression of wt p53 also leads to cell cycle arrest and protection from doxorubicin (Dox)- and melphalan (Mel)-induced apoptosis. The addition of IL-6 resulted in cell cycle progression and blocked p53-mediated protection from apoptosis. ANBL6 is an IL-6-dependent cell line that is sensitive to dexamethasone (Dex), Dox, and Mel. IL-6 is able to protect ANBL6 cells from Dex- and Mel- but not Dox-induced apoptosis. To study the effect of an activating mutation in ras, the ANBL6 cell line transfected with either a constitutively activated N- or K-ras gene was used. Both N-ras12 and K-ras12 genes were able to protect ANBL6 cells from apoptosis induced by Dex, Dox, and Mel. These data show that changes in ras or p53 can alter the myeloma cell response to IL-6 and demonstrate that the genetic background can alter therapeutic responses.

Prognostic value of serum markers of bone metabolism in untreated multiple myeloma patients

Bone involvement is a central feature of multiple myeloma (MM). We investigated whether serum markers of osteoblastic and osteoclastic activity correlate with the presence of bone disease and survival in 313 MM patients enrolled in a phase III trial (E9486). Five markers were measured, including osteocalcin (OC), carboxy-terminal propeptide of type I collagen (PICP), bone alkaline phosphatase (BAP), carboxy-terminal telopeptide of type I collagen (ICTP) and tartrate-resistant acid phosphatase (TRAP). We analysed the relationship between serum levels of these markers and the presence of bone manifestations, and survival. Serum levels of ICTP and BAP correlated significantly with bone pain, lesions and fractures. Serum level of ICTP was also higher in stage II-III compared with stage I disease. The serum level of ICTP was significantly associated with shortened survival in the univariate analysis. The median survival times were 4.1 and 3.5 years for low and high ICTP respectively (P = 0.02). There was a strong relationship between ICTP and beta-2-micrgolobulin (B2M). ICTP stands out as a significant marker of bone disease. Incorporation of these markers into clinical trials assessing the use of bisphosphonates in MM is needed to determine whether they might serve as indicators of effectiveness of these agents.

The addition of interferon or high dose cyclophosphamide to standard chemotherapy in the treatment of patients with multiple myeloma: phase III Eastern Cooperative Oncology Group Clinical Trial EST 9486

BACKGROUND

Interferon (IFN) has demonstrated activity in the treatment of patients with multiple myeloma. A previous Eastern Cooperative Oncology Group (ECOG) study suggested that the rates of complete response (CR) and survival were increased with a regimen that alternated IFN with chemotherapy. The current study was designed to evaluate the effect of adding alternating cycles of IFN or early intensification with high dose cyclophosphamide (HiCy) to the VBMCP regimen for the treatment of multiple myeloma patients.

METHODS

From February 1988 to May 1992, the ECOG entered previously untreated patients with active multiple myeloma on a study in which they were randomized to VBMCP (vincristine 1.2 mg/m(2) administered intravenously [i.v.] on Day 1, BCNU 20 mg/m(2) i.v. on Day 1, melphalan 8 mg/m(2) administered orally [p.o.] on Days 1-4, cyclophosphamide 400 mg/m(2) i.v. on Day 1, and prednisone 40 mg/m(2) p.o. on Days 1-7; 5-week cycles) or VBMCP + rIFN(alpha2), the latter given at 5 Mu/m(2) 3 times a week starting on Day 22 of each 6-week cycle after 2 initial cycles of VBMCP. Patients younger than 70 years were also randomized to a third treatment that substituted cyclophosphamide 600 mg/m(2) i.v. on Days 1-4 and prednisone 100 mg/m(2) p.o. on Days 1-4 for cycles 3 and 5 of VBMCP (VBMCP + HiCy). Treatment was continued for 2 years.

RESULTS

Of the 653 patients entered, 628 were eligible for the study. All were evaluated for response. With median follow-up for surviving patients of 54 months, the median survival duration was 42 months-1 year longer than usually reported for melphalan combined with prednisone. A comparison of the three regimens revealed no significant difference in the rates of survival or objective response (OR). However, CRs were increased among patients treated with VBMCP + rIFN(alpha2) compared with VBMCP alone (18% vs. 10%, P = 0.03). Patients treated with VBMCP + rIFN(alpha2) had a longer response duration than patients treated with VBMCP alone (30 vs. 25 months, P = 0.035). There was a greater response rate with the IFN regimen among elderly patients (OR and CR = 67% and 31%, respectively) and patients with immunoglobulin A (IgA) myeloma (OR and CR = 83% and 29%, respectively). Severe infections were seen as often with VBMCP as with VBMCP + rIFN(alpha2) (13% vs. 15%), but they were more frequent with VBMCP + HiCy (25%).

CONCLUSIONS

VBMCP + rIFN(alpha2) yields a higher rate of CR and a longer response duration than VBMCP alone but appears to make no difference in the rates of overall response or survival compared with VBMCP or VBMCP + HiCy. The superior ability of VBMCP + rIFN(alpha2) induction therapy to produce CR and more durable responses, as well as its activity in older patients and in those with IgA myeloma, suggest that this therapy has important biologic activity in myeloma and merits further clinical investigation.

Is flow cytometric DNA content hypodiploidy prognostic in multiple myeloma?

Hypodiploid multiple myeloma is uncommon when assessed by DNA content flow cytometry, having been reported in less than 6% of patients with newly diagnosed multiple myeloma. Previous studies have shown these patients to be unresponsive to therapy and to have short survival. To address this further, we studied 349 of 504 patients eligible for Eastern Cooperative Oncology Group (ECOG) treatment trial E9486 and laboratory correlative study E9487 who had marrow mononuclear cells available for ploidy analysis. Marrow samples were studied by dual channel flow cytometry, using propidium iodide to measure the DNA content and kappa and lambda light chain antisera to identify the clonal cells. A DNA index < 0.95 was considered hypodiploid. Five patients (1.4%) were found to have hypodiploid DNA content in their marrow plasma cells. Three of the 5 patients with hypodiploid myeloma had a partial objective response to chemotherapy, which is not different from the overall objective response rate for all patients enrolled on E9486. All five patients with hypodiploid multiple myeloma died within 4 years from diagnosis, but these patients had a similar overall median survival (2.6 years) compared to the patients with diploid DNA content. Our studies confirm the poorer survival of patients with diploid versus hyperdiploid myeloma; we cannot confirm, however, the previously reported very poor outcome associated with hypodiploid myeloma using DNA content flow cytometry. Hypodiploid DNA content of plasma cells by flow cytometry may not be as ominous a factor as previously reported.

Gene targeting of the KI-KII sequence elements in a model pre-B cell line: effects on germline transcription and rearrangement of the kappa locus

To study the role of individual sequence elements in the coordinate regulation of rearrangement and germline transcription of the kappa locus, we have (developed a gene targeting system with a mouse model pre-B cell line, 38B9. This line can be induced to initiate K germline transcription and V J rearrangement. Importantly, the effects of gene disruption in the cell line can be analyzed independent of selective pressures that may mask effects in the developing immune system of the mouse. We focused our study on targeting mutation of the endogenous KI KII sequence elements to allow a direct comparison with the same gene disruption reported in mouse studies. Mutations were targeted to one allele, and effects on induced transcription and rearrangement were compared to the remaining wild type allele. Our results show that KI KII mutation has little effect on germline transcription, and reduced the frequency of rearrangement two fold compared to the wild type allele. This report demonstrates that the use of model pre-B cell lines for targeted gene disruption is an attractive alternative to targeting the germline of the mouse.

Altered T cell repertoire usage in CD4 and CD8 subsets of multiple myeloma patients, a Study of the Eastern Cooperative Oncology Group (E9487)

Previous investigations have demonstrated that an expanding circulating T cell population is able to modulate the malignant clone in multiple myeloma. More recently, an expansion of T cell subsets exhibiting a restricted T cell repertoire has been detected in some MM patients. To further elucidate if a selected T cell expansion occurs in MM, we studied the T cell receptor (TCR) variable (V) region expression from a cohort of previously diagnosed and treated MM patients (N=37). The latter was done by assessing the reactivity of a panel of monoclonal antibodies specific for different V region families (alpha or beta) in combination with anti-CD4 or anti-CD8, for purified blood T cells from MM patients. TCR V region usage in MM patients was compared to blood T cells from age matched (N=13) control individuals. The multivariate analysis of variance did not uncover a difference for distribution of TCR V region usage between the normal controls and the MM cohort. However, there were individual MM patients who had expanded T cells with specific TCR V region expression when compared to the control group. Several MM patients had multiple, expanded CD4 and/or CD8 subsets based on TCR V region expression. The majority of MM patients had expanded T cell subsets that constituted less than 10% of the total blood T cell pool. However, a few MM patients (N=3) had larger percentages (range 34-84%) of these expanded T cell subsets within their blood T (CD3+) cells. The stage of disease and treatment status (currently on or off therapy) did not associate with the pattern of restricted T cell repertoire. Finally, a smaller cohort of newly diagnosed, untreated MM patients (N=13) also demonstrated an expanded T cell repertoire. However, these patients had more CD4 than CD8 cell subsets involved in the altered V region expression in several Vbeta families. Thus, these results add to the evidence that this malignant B cell disorder whether newly diagnosed or of longer duration, may be accompanied by an altered T cell repertoire characterized in part by expanded T cell clones.

Interferon-alpha protects myeloma cell lines from dexamethasone-induced apoptosis

Because of the increasing use of IFN-alpha in both induction and maintenance therapy for multiple myeloma (MM), its effect on growth and apoptosis of myeloma cells is important to consider. To investigate the role of IFN-alpha on the growth of myeloma cells, we have studied its effects on the response of interleukin 6 (IL-6)-dependent myeloma cell line (ANBL6) and IL-6-independent myeloma cell line (C2E3) in the presence of IL-6 and dexamethasone (Dex). We found that although IFN-alpha is a potent inhibitor of proliferation, it has only a minimal effect on induction of apoptosis. Moreover, we found IFN-alpha as well as IL-6 can significantly suppress dexamethasone-induced apoptosis. The suppression of apoptosis is concurrent with the induction of both AP-1 and STAT binding activity. We also found that IL-6 but not IFN-alpha up-regulates Bcl-X(L) expression. However, IL-6-mediated Bcl-X(L) expression is suppressed in the presence of Dex. Therefore, the expression of Bcl-X(L) does not account for the protection of Dex-induced apoptosis by IFN-alpha and IL-6. Taken together, our results suggest that IFN-alpha may counteract the beneficial effects of corticosteroids or perhaps other apoptosis inducing agents in the treatment of myeloma.

Developmental regulation of the kappa locus involves both positive and negative sequence elements in the 3' enhancer that affect synergy with the intron enhancer

Expression of the mouse immunoglobulin kappa locus is regulated by the intron and 3' enhancers. Previously, we have reported that these enhancers can synergize at mature B cell stages. Here we present our recent studies on the identification and characterization of the 3' enhancer sequences that play important roles in this synergy. By performing mutational analyses with novel reporter constructs, we find that the 5' region of the cAMP response element (CRE), the PU. 1/PIP, and the E2A motifs of the 3' enhancer are critical for the synergy. These motifs are known to contribute to the enhancer activity. However, we also show that mutating other functionally important sequences has no significant effect on the synergy. Those sequences include the 3' region of the CRE motif, the BSAP motif, and the region 3' of the E2A motif. We have further demonstrated that either the 5'-CRE, the PU.1/PIP, or the E2A motif alone is sufficient to synergize with the intron enhancer. Moreover, the PU.1 motif appears to act as a negative element at pre-B cell stages but as a positive element at mature B cell stages. We have also identified a novel negative regulatory sequence within the 3' enhancer that contributes to the regulation of synergy, as well as developmental stage and tissue specificity of expression. While the levels of many of the 3' enhancer binding factors change very little in cell lines representing different B cell stages, the intron enhancer binding factors significantly increase at more mature B cell stages.

Plasmablastic morphology--an independent prognostic factor with clinical and laboratory correlates: Eastern Cooperative Oncology Group (ECOG) myeloma trial E9486 report by the ECOG Myeloma Laboratory Group

We studied the prognostic significance of plasmablastic (PB) multiple myeloma (MM) in Eastern Cooperative Oncology Group Phase III trial E9486. Two reviewers independently reviewed 453 cases. They agreed on 37 PB (8.2%) cases and 416 non-PB cases, achieving an 85% concordance (P < .0001). These PB cases had significantly lower hemoglobin and serum albumin levels, higher calcium and beta 2-microglobuin levels, and higher percentage BM plasma cells (PC) by immunofluorescence. They had higher bone marrow PC labeling indices, higher serum soluble interleukin-6 receptor (sIL-6R) levels, and a higher probability of ras mutations. Three treatment regimens were used: vincristine, bis-chloro-ethyl nitrosourea (BCNU) melphalan, cyclophosphamide, and prednisone (VBMCP) alone; VBMCP with added cyclophosphamide (HiCy); or recombinant interferon alpha 2 (rIFNalpha2). Although the numbers are low, patients with PB had a significantly lower response rate versus non-PB MM when treated with VBMCP (treated, 47.1% v nontreated, 66.5% [P = .015]). Patients with nonresponding PB had a significantly higher progression rate than non-PB cases (30.6% v 11.8% [P < .0001]), especially with VBMCP alone (35.3% v 15.8% [P = .002]), and with added HiCy (37.5% v 9.8% [P < .0001]), but not with added rIFNalpha2. Event-free and overall survival of PB MM was shorter (median years, 1.1 v 2.7 and 1.9 v 3.7, respectively [P < .0001 for both]). In multivariate analysis, PB classification was also highly prognostic. There is no survival difference between the patients who were classified as PB by both reviewers versus patients classified as PB by only one reviewer. We conclude that PB MM is a discrete entity associated with more aggressive disease and shortened survival. Tumor cell ras mutations and increased sIL-6R may contribute to a higher proliferation rate and reduced survival. There were significant improvements in response and progression with the addition of HiCy and rIFNalpha2 to VBMCP, but the numbers were small and improved survival could not be shown.

T-helper phenotypes in the blood of myeloma patients on ECOG phase III trials E9486/E3A93

T-helper blood populations are frequently altered in multiple myeloma (MM). We measured the numbers of naive and activated cell subsets in the blood of a cohort of both previously untreated and treated MM patients. Two-colour flow cytometry to detect total CD4+, CD4+, CD4 5RA+ (naive) and CD4+, CD45RO+ (activated) subsets was then used to quantify the T-cell subsets in controls and MM patients. Previously treated MM patients either on or off treatment (n = 105) had significantly reduced (P< 0.0001) total CD4 and naive/activated cells than controls. Previously treated MM patients sampled for naive/activated cells while currently off therapy (n = 45) had no difference in the levels of CD4 and naive/activated cells compared to the currently treated patients (n = 60). However, newly diagnosed patients (n = 58) had a significantly reduced total CD4 (P = 0.023) and activated CD4 (P = 0.004), but not naive CD4 subsets, compared to controls. CD19+ cell levels above 125/microl were positively associated with higher T-helper cell levels. There was a strong positive association for better overall survival for patients with >395 CD4 cells/microl (P = 0.0001). These data indicate that MM patients at diagnosis have altered T-helper subsets, with a selective reduction in activated but not naive cells. Subsequent chemotherapy or the disease process contributes to a further reduction in CD4 cells. Importantly, the association of higher CD19+ cell levels with higher T helper cells indicates that certain myeloma patients can be identified with a more quantitatively intact immune system.

Differential induction of DNA-binding activities following CD19 cross-linking in human B lineage cells

The B cell-specific cell surface molecule CD19 is expressed at all stages of B cell development, including normal plasma cells, and mediates signal transduction via interaction with cytoplasmic effector proteins. Cross-linking CD19 on early human B lineage cells induces the formation of a CD19/Vav/phosphatidylinositol-3 kinase complex, tyrosine phosphorylation of CD19 and Vav, and activation of the Ras pathway. To further explore the ramifications of CD19 signaling, the current study examined whether phosphorylation of Elk-1, activation of activator protein-1 (AP-1), or activation of nuclear factor-kappaB (NF-kappaB) transcription factors occurred following CD19 cross-linking. The cells used were the BLIN-1 pre-B cell line expressing low levels of cell surface mu heavy chain associated with surrogate light chain and the 1E8 immature B cell line expressing cell surface mu/kappa. Lysates from CD19 cross-linked 1E8 cells induced robust phosphorylation of an Elk-1 fusion protein in vitro, whereas no phosphorylation of Elk-1 fusion protein occurred using lysates from CD19 cross-linked BLIN-1 cells. An electrophoretic mobility shift assay employing AP-1 and NF-kappaB consensus oligonucleotides was used to demonstrate that AP-1 -binding activity increased, while constitutive NF-kappaB-binding activity was not enhanced, following 2 h of CD19 cross-linking in 1E8 cells. Supershift experiments revealed that JunD and c-Fos proteins mediated anti-CD19 induced AP-1-binding activity in 1E8 cells. In contrast, CD19 cross-linking in BLIN-1 cells resulted in the induction of NF-kappaB, but had no apparent effect on AP-1-binding activity. These data suggest that CD19-mediated signal transduction activates different transcription factors at juxtaposed stages of B cell development that may culminate in the activation or suppression of distinct sets of genes.

Differential induction of DNA-binding activities following CD19 cross-linking in human B lineage cells

The B cell-specific cell surface molecule CD19 is expressed at all stages of B cell development, including normal plasma cells, and mediates signal transduction via interaction with cytoplasmic effector proteins. Cross-linking CD19 on early human B lineage cells induces the formation of a CD19/Vav/phosphatidylinositol-3 kinase complex, tyrosine phosphorylation of CD19 and Vav, and activation of the Ras pathway. To further explore the ramifications of CD19 signaling, the current study examined whether phosphorylation of Elk-1, activation of activator protein-1 (AP-1), or activation of nuclear factor-kappaB (NF-kappaB) transcription factors occurred following CD19 cross-linking. The cells used were the BLIN-1 pre-B cell line expressing low levels of cell surface mu heavy chain associated with surrogate light chain and the 1E8 immature B cell line expressing cell surface mu/kappa. Lysates from CD19 cross-linked 1E8 cells induced robust phosphorylation of an Elk-1 fusion protein in vitro, whereas no phosphorylation of Elk-1 fusion protein occurred using lysates from CD19 cross-linked BLIN-1 cells. An electrophoretic mobility shift assay employing AP-1 and NF-kappaB consensus oligonucleotides was used to demonstrate that AP-1 -binding activity increased, while constitutive NF-kappaB-binding activity was not enhanced, following 2 h of CD19 cross-linking in 1E8 cells. Supershift experiments revealed that JunD and c-Fos proteins mediated anti-CD19 induced AP-1-binding activity in 1E8 cells. In contrast, CD19 cross-linking in BLIN-1 cells resulted in the induction of NF-kappaB, but had no apparent effect on AP-1-binding activity. These data suggest that CD19-mediated signal transduction activates different transcription factors at juxtaposed stages of B cell development that may culminate in the activation or suppression of distinct sets of genes.

Sequential analysis of bone marrow and peripheral blood after stem cell transplant for myeloma shows disparate tumor involvement

Treatment with combination chemotherapy has not resulted in long-term remissions in multiple myeloma (MM) despite advances in drug discovery and protocol improvement over the last 25 years. Increasingly, peripheral blood (PB) stem cell transplants (PBSCT) are being used along with chemotherapy and total body irradiation as treatment for multiple myeloma. Although the majority of tumor cells are found within the bone marrow (BM), tumor cells circulate in the PB in patients with MM. Therefore, one potential problem with PBSCT is contamination of the stem cell harvests with tumor cells. Although substantial reduction in BM tumor load is achieved after chemotherapy and autologous transplantation, most patients still relapse. In an attempt to identify and quantitate the residual tumor within sequential BM and PB samples of patients with MM following autologous PB stem cell transplants we have used a tumor-specific detection assay, allele-specific oligonucleotide-PCR (ASO-PCR). We found that while the BM tumor burden may fluctuate in some patients by as much as 4-logs after transplant, the PB tumor remains quite stable, and does not reflect the tumor burden in the BM. Moreover, analysis of PB involvement over time was not predictive of marrow involvement or of potential relapse. These results suggest that the PB is frequently involved in MM and further indicate that it represents a compartment that is only minimally altered by intensive therapy.

Circulating blood B cells in multiple myeloma: analysis and relationship to circulating clonal cells and clinical parameters in a cohort of patients entered on the Eastern Cooperative Oncology Group phase III E9486 clinical trial

Recent analyses of circulating blood B cells in myeloma have generated controversy concerning the exact levels of these cells and whether they may represent circulating clonal tumor B cells. Previous reports suggested that CD19+ B cells are markedly increased in myeloma patients and that this population shares clonotypic rearrangements with the malignant plasma cell. We studied the numbers of CD19+ B cells by flow cytometry in previously untreated newly diagnosed myeloma patients in Eastern Cooperative Oncology Group (ECOG) phase III trial E9486. There were 628 patients who were eligible for the clinical protocol E9486, but of these 521 were also entered on the companion laboratory study (E9487) and had CD19 data. In comparison with normal controls, the myeloma patients exhibited a marked heterogeneity in the number of circulating CD19+ B cells as detected by flow cytometry. Approximately 20% of patients had significantly increased levels of circulating CD19+ B cells. However, the total CD19+ blood population from myeloma was not significantly different from the median of age-matched, normal controls. Analysis of CD19+ blood cells in relationship to circulating clonal cells was done in 13 myeloma patients using a clonotypic, quantitative allele-specific oligonucleotide-polymerase chain reaction (PCR) assay. No correlation was found between the numbers of CD19+ B cells (range, 5% to 51%) and PCR estimates of the number of clonal cells in the peripheral blood (range, .009% to 3.6%). Low CD19+ B-cell level (<125 microL) was associated with clinical stage III (P = .033). A significant relationship exists between higher levels (> or = 125/microL) of CD19 cells and longer overall survival (P < .0001). In addition, high CD19 levels also predicted a clinical response and longer event-free survival. There was a strong inverse association between the level of CD19 values at diagnosis and infections within the first 2 months of diagnosis. Importantly, the number of deaths related to infections was significantly greater in the low versus high CD19 group (P < .0202). Also, CD19 is an independent prognostic factor in addition to plasma cell labeling indices, beta2-microglobulin, hemoglobin, and plasmablastic morphology. Patients with infections were more likely to have low levels of CD19+ cells. In summary, higher CD19+ cell levels are a favorable prognostic sign with no apparent relationship to circulating tumor cells. In addition, this analysis strongly suggests that low peripheral blood levels of CD19+ cells are an adverse prognostic sign in myeloma. The CD19+ cell levels in myeloma patients is an important parameter in the overall assessment of these patients.

Activating mutations in the N- and K-ras oncogenes differentially affect the growth properties of the IL-6-dependent myeloma cell line ANBL6

Although the underlying genetic defect in multiple myeloma is unknown, activating mutations in the N- and K-ras oncogenes are common. Recent studies have suggested that ras mutations are associated with disease progression. We have introduced an activated N-ras12, N-ras61, or K-ras12 cDNA into the interleukin 6 (IL-6)-dependent multiple myeloma cell line ANBL6 to determine the effect of N- and K-ras on the growth/death properties of ANBL6. All three transduced cell populations demonstrate a growth advantage over the parent ANBL6 when propagated on normal human bone marrow stromal cells. In the absence of bone marrow stromal cells, augmentation of growth was observed in all three mutant ras-expressing populations at optimal and suboptimal concentrations of IL-6. Furthermore, in the absence of IL-6, all mutant ras populations demonstrated an augmentation in DNA synthesis when compared to the parent ANBL6. However, growth of the K-ras12 population in the absence of IL-6 was significantly inhibited when compared to the mutant N-ras populations. This could be explained by the observation that in the absence of IL-6, N-ras12 and N-ras61 suppress apoptosis, whereas K-ras12 does not. We also found that mutant ras expression could result in early protection from glucocorticoid-induced apoptosis similar to that observed by the addition of IL-6. However, the combination of mutant ras and IL-6 could completely block the glucocorticoid induction of apoptosis in long-term cultures. These data suggest that mutations in different ras family members may have similar or distinct effects on myeloma tumor growth and death and may alter the response to glucocorticoid treatment.

Octamer independent activation of transcription from the kappa immunoglobulin germline promoter

Previous analyses of immunoglobulin V region promoters has led to the discovery of a common octamer motif which is functionally important in the tissue-specific and developmentally regulated transcriptional activation of immunoglobulin genes. The germline promoters (Ko) located upstream of the J region gene segments of the kappa locus also contain an octamer motif (containing a single base pair mutation and referred to as the variant octamer) which has been shown previously to bind Oct-1 and Oct-2 transcription factors in vitro. To further elucidate the role of this variant octamer motif in the regulation of germline transcription from the unrearranged kappa locus, we have quantitated the relative binding affinity of Oct-1 and Oct-2 for the variant octamer motif and determined the functional role of this octamer motif in transcriptional activation. We find that, although the variant octamer motif binds Oct-1 and Oct-2 in vitro with 5-fold lower affinity than the consensus octamer motif, mutation of the variant octamer motif to either a consensus octamer or non-octamer motif has no effect on transcriptional activation from the germline promoter. We also find significant differences in activation of germline and V region promoters by kappa enhancers. Our results suggest that the germline promoters and V region promoters differ in their dependence on octamer for activation and respond differently to enhancer activation. These findings have important implications in regulation of germline transcription as well as concomitant activation of the V-J recombination of the kappa light chain locus.

Activating mutations of N- and K-ras in multiple myeloma show different clinical associations: analysis of the Eastern Cooperative Oncology Group Phase III Trial

Mutations of members of the ras family are among the most common oncogene mutations found in multiple myeloma (MM). We have examined the mutational status of the N- and K-ras genes at codons 12, 13, and 61 in 160 newly diagnosed MM patients enrolled on the Eastern Cooperative Oncology Group (ECOG) phase III clinical trial E9486. The total incidence of ras mutations was found to be 39% of the samples analyzed. Five patients showed evidence of more than one mutation. We obtained 22 marrow samples from patients at the time of disease progression or relapse, for whom a ras mutation was identified at diagnosis. In all cases, the ras mutation of the disease progression sample was identical to that found at diagnosis. In contrast, three of 25 patients who did not show any ras mutation at diagnosis acquired a ras mutation at the time of disease progression. No significant association was observed between any ras mutation and stage of disease, beta 2-microglobulin levels, labelling index, or protein type. The mean tumor burden and median survival for patients with mutations of N-ras was indistinguishable from patients with no ras mutations. However, patients with K-ras mutations had a significantly higher mean bone marrow tumor burden at diagnosis than patients with no ras mutations (57% v 36%, P < .02); and the median survival of patients with a K-ras mutation was significantly shorter (2.0 v 3.7 years, P < .02). To determine if the status of ras mutations could affect treatment response, we examined patient survival on the three treatment arms of E9486. Although the presence of a ras mutation in the multidrug treatment, VBMCP alone, showed a marginal significance, neither the VBMCP, nor the addition of interferon-alpha showed statistically significant survival differences between mutant and wildtype ras status. Interestingly, there appeared to be a statistically significant difference in survival of patients treated with VBMCP and alternating high doses of cyclophosphamide + prednisone. Patients with ras mutations had a median survival of 2.1 years; patients with wild-type ras had a median survival of 4.0 years (P < .01).

Clonal circulating cells are common in plasma cell proliferative disorders: a comparison of monoclonal gammopathy of undetermined significance, smoldering multiple myeloma, and active myeloma

The blood of most patients with active multiple myeloma (MM) contains cells related to the bone marrow tumor. However, identifying clonal cells in the blood of patients with monoclonal gammopathy of undetermined significance (MGUS) has been difficult. In this study, we analyzed blood mononuclear cells (BMNCs) from 16 patients with MGUS, 2 with amyloidosis, 8 with smoldering MM (SMM), 2 with indolent MM (IMM), and 15 with active MM using three different methods to detect and quantitate clonal cells, ie, immunofluorescence microscopy (IM) for monoclonal plasma cells, three-color flow cytometry (FC) for CD38(+)CD45- CD45(dim) cells, and the allele-specific oligonucleotide polymerase chain reaction (ASO-PCR). Using ASO-PCR, we were able to detect clonal cells in the blood in 13 of 16 patients with MGUS, 2 of 2 with amyloid, 6 of 8 with SMM, 2 of 2 with IMM, and 13 of 15 with MM. In 9 of the 13 patients with MGUS with blood involvement, the number of clonal cells was very small ( < 0.04% of the BMNCs). The median percentage of clonal cells as determined by ASO-PCR was 0.02 for MGUS, 0.02 for SMM, and 0.24 for MM. Clonal plasma cells or CD38+CD45-CD45(dim) cells were identified by IM or FC in 6 of 16 MGUS patients, 4 of 8 with SMM, and 11 of 15 with MM. In all cases in which IM or FC detected clonal cells, the ASO-PCR was positive. This study shows that, by using ASO-PCR, clonal cells can be found at very low levels in the blood in most patients with MGUS. However, the number of clonal cells in the blood of MGUS patients is less than those with overt MM (P = .006). In contrast to MGUS, patients with active MM are more likely to have identifiable clonal circulating plasma cells (P = .05).

Introduction of an activated N-ras oncogene alters the growth characteristics of the interleukin 6-dependent myeloma cell line ANBL6

Multiple myeloma (MM) is a late-stage B-cell cancer with an unknown etiology. Activating mutations of the N-ras and K-ras oncogenes occur with a high frequency in myeloma and, therefore, may play a role in the pathogenesis of the disease. To study the role of N-ras-activating mutations in the regulation of myeloma tumor growth, we introduced a constitutively active N-ras cDNA containing a glutamine to arginine (CAA-CGA) amino acid substitution at codon 61 into the interleukin 6 (IL-6)-dependent myeloma cell line ANBL6. Expression of the mutant N-ras cDNA resulted in significant IL-6-independent growth, as well as augmentation of growth at suboptimal concentrations of IL-6. The IL-6-independent growth pattern was not the result of activation of autocrine IL-6 production in the mutant N-ras-expressing population because neutralizing antibodies to the IL-6 receptor and to IL-6 had no effect on the rate of DNA synthesis in the absence of IL-6. Furthermore, mutant N-ras expression decreased the percentage of cells undergoing apoptosis in the absence of IL-6. These data suggest that activating mutations of the ras oncogenes may result in growth factor independence accompanied by a suppression of apoptosis in MM. Therefore, the use of therapies designed to block IL-6 action in MM may have less of an impact on tumors bearing activated ras mutations.

Sequential phenotyping of myeloma patients on chemotherapy: persistence of activated T-cells and natural killer cells

To better detail the status of functional T cell subsets and natural killer cells in multiple myeloma, we undertook a detailed immunophenotypic study of circulating mononuclear cells in myeloma. We studied myeloma patients entered on a large prospective, randomized ECOG chemotherapy trial EST 9486 for patients with newly diagnosed multiple myeloma. All patients were studied prior to entry and then two months after initiation of therapy (e.g. post two cycles of Vincristine, BCNU, melphalan, cyclophosphamide and prednisone (VBMCP)). The chemotherapy protocol was a three-arm protocol utilizing either VBMCP, VBMCP alternating with interferon, or VBMCP with intermittent high dose cyclophosphamide. The major findings in this analysis include significant reductions in the white blood cell count, total lymphocytes, T cell (CD3+), T helper (CD4+), and T suppressor (CD8+) cells, after 2 cycles of VBMCP. However, there was a relative sparing of Natural killer (CD16+) and activated T cell (CD2+, HLADR+) reduction in these same patients. In summary, only two cycles of combination chemotherapy resulted in significant reductions in white blood cell and lymphocyte counts in multiple myeloma patients. All cell types appear to have been reduced by chemotherapy except for activated T cells and natural killer cells. The impact of selective modulation of functional T cells subsets during therapy for patients with multiple myeloma is an important parameter which needs to be addressed in the overall approach to these patients.

An AP1 binding site upstream of the kappa immunoglobulin intron enhancer binds inducible factors and contributes to expression

Expression of the kappa immunoglobulin light chain gene requires developmental- and tissue-specific regulation by trans-acting factors which interact with two distinct enhancer elements. A new protein-DNA interaction has been identified upstream of the intron enhancer, within the matrix-associated region of the J-C intron. The binding activity is greatly inducible in pre-B cells by bacterial lipopolysaccharide and interleukin-1 but specific complexes are found at all stages of B cell development tested. The footprinted binding site is homologous to the consensus AP1 motif. The protein components of this complex are specifically competed by an AP1 consensus motif and were shown by supershift to include c-Jun and c-Fos, suggesting that this binding site is an AP1 motif and that the Jun and Fos families of transcription factors play a role in the regulation of the kappa light chain gene. Mutation of the AP1 motif in the context of the intron enhancer was shown to decrease enhancer-mediated activation of the promoter in both pre-B cells induced with LPS and constitutive expression in mature B cells.

Kappa immunoglobulin promoters and enhancers display developmentally controlled interactions

We have investigated the interaction of the kappa immunoglobulin light chain intron and 3' enhancers with two different kappa promoters at distinct stages of B-cell development. We find that transiently transfected reporter gene constructs driven by either the kappa V-region promoter, or the kappa germline promoter, are controlled by the known enhancers of the locus in a developmentally regulated fashion. We have, however, observed differences in promoter activation by each enhancer. Moreover, constructs controlled by a combination of both enhancers are synergistically activated at the B-cell and plasma cell stages as compared with constructs containing either enhancer alone. This synergy is not observed early in development, at the pre-B cell stage. The pattern of enhancer and promoter interactions is discussed in the context of the known developmental regulation of the locus.

The bone marrow of multiple myeloma patients contains B cell populations at different stages of differentiation that are clonally related to the malignant plasma cell

One of the distinguishing features of multiple myeloma (MM) is the proliferation of a clonal plasma cell population in the bone marrow (BM). It is of particular interest that the tumor plasma cells appear to be restricted to the microenvironment of the BM and are rarely detected in the peripheral system, yet the disease is found widely disseminated throughout the axial skeleton. Furthermore, isolation of MM tumor cell lines has proven to be quite problematic due to their slow growth rate. These observations have instigated the search for earlier cells in the B cell lineage that are clonally related to the plasma cell tumor and that may represent the growth fraction of the tumor. We used allele-specific oligonucleotides (ASO) derived from the third complementarity determining region of the rearranged tumor immunoglobulin heavy chain gene to detect isotypes clonally related to the plasma cell tumor. By reverse transcribing RNA from the BM with a panel of CH primers (mu, delta, alpha, and gamma), followed by ASO-polymerase chain reaction amplification, we demonstrate the existence of preswitch isotype species that are clonally related to the myeloma tumor. Furthermore, we show that separation of the BM cells into CD45+ and CD38+ cell populations results in a lineage-specific expression of the clonally related RNA molecules, with the C mu and C delta in the CD45+, and C gamma in the CD38+ population. Interestingly, clonally related C alpha transcripts are also derived from the CD45+ fraction. These results confirm the presence of B cell populations clonally related to the plasma cell tumor and are consistent with models that propose the existence of myeloma precursors.

Rearrangement and diversification of T-cell receptor delta genes in acute lymphoblastic leukemia

The current study was designed to determine the nucleotide sequence of two distinct T-cell-receptor delta chain (TCR delta) rearrangements which account for 95% of all rearranged alleles in common non-T, non-B lymphoid precursor acute lymphoblastic leukemia (LP-ALL). The results presented demonstrate that TCR delta rearrangements in LP-ALL are incomplete, immature, and involve V delta 2 to D delta 3 or D delta 2 to D delta 3 joints. These rearrangements are found in most cases of ALL. These results are consistent with the hypothesis that these leukemias originate in multipotent lymphoid precursor cells. The remarkable diversity of the rearrangements detected by polymerase chain reaction, cloning and sequencing demonstrates the clonal specificity and potential for detection of leukemic residual disease. However, in some cases the number of nucleotide differences may not be sufficient for the discrimination of leukemic and non-leukemic cells carrying V delta 2-(D)-D delta 3 rearrangements. A novel inversional rearrangement was demonstrated in one leukemia. This novel inversional rearrangement potentially increases the degree of diversity of the junctional region which encodes the antigen binding domain of TCR delta.

Lymphoid lineage-associated features in acute myeloid leukaemia: phenotypic and genotypic correlations

This study is intended to establish biological correlation between the expression of lymphoid associated features in acute myeloid leukaemia (AML). In 62 AML patients, predominantly enrolled on Eastern Cooperative Oncology Group (ECOG) treatment protocols, in whom immunoglobulin (Ig) as well as T-cell receptor beta chain (TCR-beta) gene rearrangement analyses had been performed, morphology, cytochemistry, antigen profile and karyotype were reviewed retrospectively. Nuclear reactivity with anti-TdT antibody was demonstrated in 34 patients (55%) and confirmed by ribonuclease protection assay in all patients tested. Five TdT-protein negative patients were TdT-transcript positive. Lymphoid antigens (lyA) were detected in 24 of 51 cases tested (47%) with B-cell antigens (CD19, CD10) being restricted to TdT+ AML (P = 0.03). Only two patients had Ig heavy, none had Ig light chain or TCR-beta gene rearrangements. Although both patients with rearranged Ig loci were TdT+, either by protein or RNA analysis, the low incidence of such rearrangement within the TdT+ AML group (6%) argues against a significant association between the presence of TdT and crosslineage Ig gene rearrangements in AML. While FAB-diagnoses did not differ between TdT+ and TdT- or lyA+ and lyA- AML, particular immunophenotypic features correlated with TdT positively, e.g. the presence of early antigens, CD34 and HLA-DR, and the absence of the more mature myelo-monocytic antigens, CDw65 and CD14. Certain cytogenetic abnormalities were associated with TdT+ AML such as inv(16) (p13q22) or t(16;16) (p12;q22) (five patients; P = 0.03) and t(8;21) (q22;q22) (three patients). A greater number of TdT- than TdT+ AML patients had only normal karyotypes (P = 0.06). Neither immunophenotypic nor karyotypic correlations could be established for lyA+ AML.

Detection and quantitation of malignant cells in the peripheral blood of multiple myeloma patients

One of the distinguishing features of multiple myeloma (MM) is the proliferation of plasma cells that home to the bone marrow (BM). However, there still remains some uncertainty concerning the presence of related malignant cells in the peripheral blood of myeloma patients. Using consensus oligonucleotide primers, we amplified the third complementary determining region (CDR3) of rearranged immunoglobulin heavy chain alleles from MM marrow samples by polymerase chain reaction (PCR). From the sequences of the products, we derived allele-specific oligonucleotides (ASO), and these were used in subsequent amplification reactions to detect malignant clones in the peripheral blood of myeloma patients. This method is highly specific and sensitive to 1 malignant cell in the background of 10(5) normal cells. Using this method we detected circulating malignant cells in 13 of 14 previously untreated MM patients. Furthermore, by applying ASO-PCR to artificial titrations of initial BM DNA sample into normal peripheral blood lymphocyte (PBL) DNA we were able to generate standard curves and quantitate the amount of tumor in the patient PBL. We observed a wide variation in the amount of circulating tumor between patients. In addition, we found that the incidence of circulating tumor cells was independent of BM tumor burden and stage of disease. The detection and quantitation of circulating tumor cells in the PBL of MM patients may offer an alternative assessment of the disease and may be an important consideration in the use of peripheral stem cells in bone marrow transplantation.

B-chronic lymphocytic leukemia cells contain both endogenous kappa immunoglobulin mRNA and critical immunoglobulin gene activation transcription factors

B-cell chronic lymphocytic leukemia (B-CLL) is a hematologic malignancy characterized by the proliferation and accumulation of mature-looking B lymphocytes. Patients with B-CLL exhibit a number of immune defects including: auto-antibodies, depressed cell-mediated immunity and hypogammaglobulinemia (HG). We investigated the control of Ig production in the malignant CLL B-cell at a transcriptional and translation level. We isolated fresh leukemic B-cells from CLL patients and analyzed for the presence of nuclear factors OCT-1, OCT-2, and NF-KB. Malignant B-cells were purified to greater than 90% B-cells, and total cellular RNA and nuclear proteins were isolated from these cells. Mobility shift assays were probed with 32P-labeled oligonucleotides specific to the immunoglobulin (Ig) enhancer and promotor regions. We detected endogenous OCT-1, OCT-2, and NF-KB in all patients tested (n = 5). We then evaluated whether activation of CLL B cells could augment kappa-mRNA levels. CLL cells (n = 3) exposed to phorbol ester and A23187 were harvested at 0, 2, 4, 8, and 48 min and examined for kappa-mRNA by Northern blot. All CLL patients (n = 3) had easily detectable levels of endogenous kappa-mRNA. However, only one patient had an obvious increase in kappa-mRNA post-induction with TPA/A23187. There was no concomitant increase in this patient's OCT-1, OCT-2, or NF-KB level. This finding prompted us to survey other B-CLL patients (n = 6) for Ig nuclear transcriptional factors pre- and post-induction. In summary, CLL B cells express Ig transcriptional factor OCT-1, OCT-2, and NF-KB constitutively. The endogenous level of NF-KB may account for the basal kappa-mRNA detected in B-CLL cells. However, the inability to augment NF-KB levels may, in part, explain the low levels of Ig synthesis in CLL B-cells.

Translocation (2;9)(p12;p23) in a case of acute leukemia with t(4;11)(q21;q23). Lack of rearrangement of the kappa and interferon gene loci

A case is reported of an adult male patient with acute leukemia characterized by the presence of the novel cytogenetic abnormality, t(2;9)(p12;p23), in addition to a t(4;11)(q21;q23). The immunophenotype of the blast cell population was consistent with immature early pre-B cell acute lymphoblastic leukemia (ALL) (TdT+,HLA-DR+,CD19+,CD24 +/-,CD10-) expressing myelo-monocytic antigens (CDw65,CD15). The genotype showed a clonal rearrangement of the immunoglobulin heavy chain locus. Because the immunoglobulin kappa (kappa) light chain gene is located on chromosome 2 at band p12 and interferon alpha (alpha) and beta (beta) map to chromosome 9p21-p22, rearrangements of these loci as a result of the t(2;9) were studied. There was no evidence for rearrangement of the region covering about 40 kilobases around the kappa locus when hybridized to C(kappa), the 3' kappa enhancer or the kappa deleting element. Only germline size restriction fragments were also found for the interferon alpha and beta genes. The patient's clinical features were typical for ALL associated with the t(4;11), including a high white blood cell count at presentation, hepatosplenomegaly, and a poor outcome. The potential significance of 2p and 9p abnormalities in addition to t(4;11) is discussed.

Analysis of B-lymphoid malignancies using allele-specific polymerase chain reaction: a technique for sequential quantitation of residual disease

The junctional sequences corresponding to the complementarity determining region 3 (CDR3) of rearranged heavy chain Ig genes can provide allele-specific markers in the detection of B-lymphoid malignancies. Consensus oligonucleotide primers were used to amplify CDR3 regions of rearranged heavy chain alleles in clinical samples from myeloma, acute lymphocytic leukemia, and chronic lymphocytic leukemia patients. From the sequence of the amplified products, allele-specific primers were synthesized and used directly in polymerase chain reaction (PCR) amplification to detect the malignant clone. This method was both highly specific and sensitive to 1 malignant B-cell in a background of 10(5) normal cells. In addition, parameters that affect the linearity of PCR detection were determined and, by using titrations of malignant target cells to generate standard curves, quantitations of residual malignancies were determined. The application of this method is shown in an analysis of myeloma patients whose marrows were analyzed sequentially during therapy. Allele-specific oligonucleotide-PCR provided a rapid, highly specific and quantitative measure of residual disease, even in patients with clinical parameters indicating complete remission.

Induced rearrangement of kappa genes in the BLIN-1 human pre-B cell line correlates with germline J-C kappa and V kappa transcription

The human pre-B acute lymphoblastic leukemia cell line, BLIN-1, has been previously shown to undergo kappa light chain rearrangement in vitro, making it a valuable resource for analyzing pre-B to B cell differentiation. We have examined the recombination potential of BLIN-1 by characterizing several independently derived kappa-expressing subclones for DNA rearrangement and V kappa gene usage. Analysis of five kappa-expressing subclones (all having the same heavy chain rearrangement) demonstrated independent kappa light chain rearrangement events by DNA hybridization analysis. Northern blot analysis using probes recognizing the four different V kappa families revealed that two subclones used the most proximal V kappa (V kappa IV), one subclone used a V kappa I, and one subclone used a V kappa II. By polymerase chain reaction analyses, we detected transcripts from rearranged V-J-C kappa genes as well as transcripts from germline J-C kappa and V kappa in BLIN-1 cells induced to rearrange the kappa locus. kappa germline transcripts were also detected in normal developing B cell populations in fetal liver and bone marrow. Our collective results indicate that: (a) BLIN-1 can be induced to rearrange the kappa locus, and this correlates with the expression of germline kappa locus transcripts that may play a role in activating or targeting gene rearrangement; and (b) active rearrangement and usage of V genes representing different kappa families suggest that, like in the mouse, repertoire diversification in humans occurs in the presence of a fixed heavy chain rearrangement.

Unexpected immunoglobulin light chain gene rearrangements in myeloid antigen positive acute lymphoid leukemia

Blast cells from 10 immunologically diagnosed adult acute lymphoid leukemias expressing myeloid antigens (M+ALL) were studied for immunoglobulin heavy (IgH) and light chain as well as T-cell receptor (TCR)-beta chain gene rearrangements. All but one leukemic isolate met the FAB-criteria for ALL. DNA from 2 patients with pre-pre-B-ALL (CD10-) and 1 patient with common ALL contained rearranged Ig light chain (kappa in two, lambda in one case) in addition to rearranged IgH genes. The TCR-beta chain gene was germline in all pre-pre-B leukemias and rearranged in common ALLs (bigenotypic features). One patient with mature B-ALL showed IgH and light chain gene rearrangements. DNA from 2 pre-T-ALLs contained rearranged TCR-beta chain genes plus rearranged IgH genes in one case. Ig light chain gene rearrangements in immature M+ALL were not associated with gross chromosomal abnormalities except for one Philadelphia chromosome positive case. The occurrence of Ig light chain gene rearrangements in M+ALL with immature lymphoid immunophenotype might represent an hitherto unrecognized aberrant differentiation potential of transformed multipotential stem cells with commitment towards the lymphoid lineage.

Identification of an octamer-binding site in the human kappa light-chain enhancer

Octamer motifs contribute to the function and tissue specificity of immunoglobulin heavy- and light-chain gene promoters and the heavy-chain enhancer. A variant octamer-binding site within a conserved region of the human kappa light-chain gene enhancer which contributes to the function of this enhancer has been identified.