Biomedical subjects

Michel Jourdan

Publications and source records attributed to Michel Jourdan.

10 recordsLinked to original sources

PubMed2006

Microarray-based understanding of normal and malignant plasma cells.

Plasma cells (PCs) develop from B lymphocytes following stimulation by antigen and express a genetic program aimed at the synthesis of immunoglobulins. This program includes the induction of genes coding for transcription factors such as PRDM1, X-box-binding protein 1 and BHLHB3, cell-surface molecules such as CD138/syndecan-1, and for the unfolded protein response. We review how the microarray technology has recently contributed to the understanding of the biology of this rare but essential cell population and its transformation into premalignant and malignant PCs.

B-Lymphocytes↗

PubMed2005

Expression of EGF-family receptors and amphiregulin in multiple myeloma. Amphiregulin is a growth factor for myeloma cells.

A hallmark of plasma cells is the expression of syndecan-1, which has major functions in epithelial cells, in particular as the coreceptor of heparin-binding growth factors. We previously found that heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a growth factor for malignant plasma cells. As amphiregulin (AREG) is another heparin-binding factor of the EGF family, we investigated its role in multiple myeloma (MM). Using Affymetrix DNA microarrays, we show here that the AREG gene was expressed by purified primary myeloma cells from 65 patients and that the expression was higher than in normal bone marrow (BM) plasma cells or plasmablastic cells. AREG stimulated IL-6 production and growth of BM stromal cells. Using real-time reverse transcriptase-polymerase chain reaction, we found that MM cells expressed ErbB receptors and that AREG promoted their growth. Furthermore, PD169540 (a pan-ErbB inhibitor) and IRESSA (an ErbB1-specific inhibitor) induced apoptosis of primary myeloma cells from 10/14 and 4/14 patients, respectively, and there was a synergistic effect with dexamethasone. Altogether, our data provide strong evidence that AREG plays an important role in the biology of MM and emphasize the advantages of using ErbB inhibitors, which might target myeloma cells as well as the tumor environment.

Amphiregulin↗

PubMed2004

The Bcl-2 family member Bfl-1/A1 is strongly repressed in normal and malignant plasma cells but is a potent anti-apoptotic factor for myeloma cells.

Terminal B-cell differentiation is a multi-step process, from short-lived plasmablasts to mature long-lived plasma cells (PC). The anti-apoptotic Bcl-2 family member Bfl-1/A1 plays a critical role in the survival of mature B cells. However, its potential involvement at the later stages of B-cell development remains highly controversial. Our aim was thus to clarify the place of Bfl-1/A1 in the biology of normal PC and in the pathogenesis of multiple myeloma (MM), the major PC dyscrasia. Using gene expression profiling and quantifiable reverse transcription polymerase chain reaction experiments, we found a similar down-regulation of Bfl-1/A1 in both normal immature plasmablasts and mature PC when compared with B cells. In myeloma cells, the level of Bfl-1/A1 was low and Bfl-1/A1 was not a nuclear factor kappaB-inducible gene. Collectively, these data demonstrate that Bfl-1/A1 is not involved in the prolonged survival of normal mature PC, and that Bfl-1/A1 deregulation is not a common oncogenic event in MM. However, overexpression of Bfl-1/A1 by retroviral transduction promoted autonomous survival of an interleukin-6-dependent myeloma cell line and rendered it less sensitive to dexamethasone. Thus, Bfl-1/A1 transduction could be an interesting tool to obtain myeloma cell lines from primary samples and to favour the in vitro generation of antibody-secreting, long-lived normal PC.

Apoptosis↗

PubMed2003

Comparison of murine leukemia virus, human immunodeficiency virus, and adeno-associated virus vectors for gene transfer in multiple myeloma: lentiviral vectors demonstrate a striking capacity to transduce low-proliferating primary tumor cells.

Genetic modification of primary tumor cells by gene transfer is of major interest to study the role of specific genes in the biology of a given malignancy and to modify tumor cells for therapeutic use. Multiple myeloma (MM) is a low-proliferating cancer, with often less than 1% of the cells in the S phase of the cell cycle. As primary myeloma cells are notoriously difficult to transduce, we conducted a comparison of various viral vectors, known to integrate the transgene of interest into the target genome, for their ability to stably promote the expression of an enhanced green fluorescent protein (EGFP) transgene. We compared three murine leukemia virus-based vectors, differing only in their viral envelope, a human immunodeficiency virus (HIV)-based vector pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G), and an adeno-associated virus type 2 vector. Transduction characteristics of these vectors were evaluated in human myeloma cell lines and in primary myeloma cells. Unequivocally, we observed that the VSV-G/HIV vector was the most efficient vector for transducing the cell lines and the only one able to transduce primary myeloma cells reproducibly. The mean percentage of transduced primary myeloma cells was 43.6% (range, 16.3-77.6%), with one round of infection at a low multiplicity of infection, including MM cell samples with less than 1% of cells in the S phase. A quantitative polymerase chain reaction assay demonstrated that this more efficient EGFP expression was associated with a higher GFP copy number in the targeted cell. We propose that lentiviral vectors should be used for transduction of nonproliferating primary tumor cells such as myeloma cells.

Adenoviridae↗

PubMed2003

An inhibitor of the EGF receptor family blocks myeloma cell growth factor activity of HB-EGF and potentiates dexamethasone or anti-IL-6 antibody-induced apoptosis.

We previously found that some myeloma cell lines express the heparin-binding epidermal growth factor-like growth factor (HB-EGF) gene. As the proteoglycan syndecan-1 is an HB-EGF coreceptor as well as a hallmark of plasma cell differentiation and a marker of myeloma cells, we studied the role of HB-EGF on myeloma cell growth. The HB-EGF gene was expressed by bone marrow mononuclear cells in 8 of 8 patients with myeloma, particularly by monocytes and stromal cells, but not by purified primary myeloma cells. Six of 9 myeloma cell lines and 9 of 9 purified primary myeloma cells expressed ErbB1 or ErbB4 genes coding for HB-EGF receptor. In the presence of a low interleukin-6 (IL-6) concentration, HB-EGF stimulated the proliferation of the 6 ErbB1+ or ErbB4+ cell lines, through the phosphatidylinositol 3-kinase/AKT (PI-3K/AKT) pathway. A pan-ErbB inhibitor blocked the myeloma cell growth factor activity and the signaling induced by HB-EGF. This inhibitor induced apoptosis of patients'myeloma cells cultured with their tumor environment. It also increased patients' myeloma cell apoptosis induced by an anti-IL-6 antibody or dexamethasone. The ErbB inhibitor had no effect on the interaction between multiple myeloma cells and stromal cells. It was not toxic for nonmyeloma cells present in patients' bone marrow cultures or for the growth of hematopoietic progenitors. Altogether, these data identify ErbB receptors as putative therapeutic targets in multiple myeloma.

Antineoplastic Agents, Hormonal↗

PubMed2003

A major role for Mcl-1 antiapoptotic protein in the IL-6-induced survival of human myeloma cells.

Interleukin-6 (IL-6) is a major survival factor for malignant plasma cells involved in multiple myeloma. Using an RNase protection assay, we looked for gene expression of 10 anti- and proapoptotic Bcl-2-family proteins in 12 IL-6-dependent human myeloma cell lines (HMCL). A high Mcl-1 gene expression was found in all HMCLs and the other genes were variably expressed. Out of the 10 Bcl-2-family members, only the Mcl-1 gene was regulated by IL-6. Upon starvation of IL-6, Mcl-1 gene expression decreased in association with myeloma cell apoptosis and was upregulated after adding IL-6 again in association with myeloma cell survival. A constitutive Mcl-1 expression was induced with an Mcl-1-GFP retrovirus in two IL-6-dependent HMCLs. The Mcl-1 HMCLs have a marked reduced apoptosis upon IL-6 starvation compared to HMCLs transduced with control GFP retrovirus and may grow without adding IL-6. These data emphasize the major role of Mcl-1 antiapoptotic protein in the IL-6-induced survival of human myeloma cells.

Antibodies↗

PubMed2003

Survival and proliferation factors of normal and malignant plasma cells.

Since the first identification of interleukin (IL)-6 as a myeloma cell growth factor by Dr. Kawano's and Dr. Klein's groups 14 years ago, numerous studies have emphasized its major roles in the emergence of malignant plasma cells in vivo and in the generation of normal plasma cells. Four transcription factors control B-cell differentiation into plasma cells. The B-cell transcription factor pax-5 is mainly responsible for a B-cell phenotype, and bcl-6 represses the plasma cell transcription factor blimp-1 and plasma cell differentiation. bcl-6 expression is triggered by CD40 and IL-4 activation. A lack of CD40 and IL-4 activation yields a down-regulation of bcl-6 expression, and IL-6 stimulation yields an up-regulation of blimp-1, mainly through STAT3 activation. Blimp-1 further down-regulates bcl-6 and pax-5 expression and makes plasma cell differentiation possible. IL-6 as well as IL-10 up-regulate XBP-1. XBP-1 is another transcription factor that is involved in plasma cell differentiation and whose gene expression is shut down by pax-5. The plasma cell transcription factors blimp-1 and XBP-1 are up-regulated, and the B-cell transcription factors bcl-6 and pax-5 are down-regulated, in malignant cells compared to B-cells. Apart from the recent identification of these 4 transcription factors, the factors involved in normal plasma cell generation are mostly unknown. Regarding malignant plasma cells, 3 categories of growth factors have been identified: (1) the IL-6 family cytokines, IL-10, and interferon alpha that activate the Janus kinase-signal transducer and activator of transcription (JAK/STAT) and mitogen-activated protein (MAP) kinase pathways; (2) growth factors activating the phosphatidylinositol (PI)-3 kinase/AKT and MAP kinase pathways, unlike the JAK/STAT pathway (insulin-like growth factor 1, hepatocyte growth factor, and members of the epidermal growth factor family able to bind syndecan-1 proteoglycan); and (3) B-cell-activating factor (BAFF) or proliferation-inducing ligand (APRIL) that activate the nuclear factor KB and PI-3 kinase/AKT pathways. BAFF and APRIL bind to BAFF receptor and TACI and are major B-cell survival factors. Recent data indicate that these various growth factors may cooperate to provide optimum signaling because they are localized together and with cytoplasmic transduction elements in caveolinlinked membrane caveolae. The identification of these myeloma cell growth factors and of the associated transduction pathways should provide novel therapeutic targets in multiple myeloma.

B-Cell Activating Factor↗

PubMed2002

Comparison of gene expression profiling between malignant and normal plasma cells with oligonucleotide arrays.

The DNA microarray technology enables the identification of the large number of genes involved in the complex deregulation of cell homeostasis taking place in cancer. Using Affymetrix microarrays, we have compared the gene expression profiles of highly purified malignant plasma cells from nine patients with multiple myeloma (MM) and eight myeloma cell lines to those of highly purified nonmalignant plasma cells (eight samples) obtained by in vitro differentiation of peripheral blood B cells. Two unsupervised clustering algorithms classified these 25 samples into two distinct clusters: a malignant plasma cell cluster and a normal plasma cell cluster. Two hundred and fifty genes were significantly up-regulated and 159 down-regulated in malignant plasma samples compared to normal plasma samples. For some of these genes, an overexpression or downregulation of the encoded protein was confirmed (cyclin D1, c-myc, BMI-1, cystatin c, SPARC, RB). Two genes overexpressed in myeloma cells (ABL and cystathionine beta synthase) code for enzymes that could be a therapeutic target with specific drugs. These data provide a new insight into the understanding of myeloma disease and prefigure that the development of DNA microarray could help to develop an 'à la carte' treatment in cancer disease.

Adult↗

PubMed2002

Cooperation between heparin-binding EGF-like growth factor and interleukin-6 in promoting the growth of human myeloma cells.

Interleukin-6 (IL-6) is a major survival and proliferation factor of human malignant plasma cells and IL-6 dependent myeloma cell lines can be obtained from patients with terminal disease. We show here that mutated diphtheria toxin, a specific inhibitor of heparin-binding epidermal growth factor-like growth factor (HB-EGF), blocked the IL-6-induced growth of two myeloma cell lines (XG-1 and XG-14) and did not significantly affect that of two other cell lines (XG-6 and XG-13). The IL-6 mediated growth of myeloma cells was also inhibited by antibodies to ErbB1, a receptor for HB-EGF. The XG-1 and XG-14 cell lines that are sensitive to HB-EGF inhibitors overexpressed HB-EGF and EGF receptor (ErbB1) genes. They also overexpressed CD9, a tetraspanin that binds to the heparin-binding domain of HB-EGF and is critical for promoting ErbB1 activation by HB-EGF. The XG-6 and XG-13 myeloma cells that were not significantly sensitive to HB-EGF antagonists, poorly expressed HB-EGF, ErbB1 and CD9 genes or proteins. We demonstrated that recombinant HB-EGF supported the long-term growth of myeloma cells, as did IL-6. The myeloma cell growth factor activity of HB-EGF was completely inhited by antibodies to ErbB1, but also by antibodies to gp130 IL-6 transducer or to IL-6. These data indicate that in the XG-1 and XG-14 IL-6-dependent myeloma cell lines, the CD9/HB-EGF/erbB1 and the IL-6/IL-6R/gp130 pathways cooperate synergistically to trigger myeloma cell growth. They suggest that inhibitors of the EGF receptor or HB-EGF may be useful for inducing myeloma cell apoptosis in patients with multiple myeloma.

Antigens, CD↗

PubMedDate not supplied

Delineation of the roles of paracrine and autocrine interleukin-6 (IL-6) in myeloma cell lines in survival versus cell cycle. A possible model for the cooperation of myeloma cell growth factors.

Primary myeloma cells rapidly apoptose as soon as they are removed from their bone-marrow environment. A likely explanation is that the tumor environment produces survival factors that may counteract a spontaneous activation of pro-apoptotic program. Additional factors may trigger cell cycling in surviving myeloma cells. Interleukin-6 (IL-6) is a well recognized myeloma cell growth factor produced mainly by the tumor environment. However, myeloma cells themselves may produce low levels of autocrine IL-6. The respective roles of paracrine versus autocrine IL-6 are a matter of debate. We investigated these roles using the XG-6 myeloma cell line whose growth is dependent on addition of exogenous IL-6, despite its weak IL-6 mRNA and protein expression. The apoptosis induced by exogenous IL-6 deprivation was blocked by transferring the Mcl-1 gene coding for an anti-apoptotic protein in XG-6 cells. An XG-6Mcl-1 cell line which can survive and grow without adding IL-6 was obtained. We show that anti-IL-6 or anti-gp130 antibodies abrogated cell cycling whereas they did not affect cell survival. These data indicate that the weak autocrine IL-6 produced by myeloma cells is sufficient to trigger cell cycling whereas their survival requires large exogenous IL-6 concentrations. This important role of autocrine IL-6 has to be considered when evaluating the mechanism of action of myeloma cell growth factors. These factors may actually block an activated pro-apoptotic program, making possible a weak production of autocrine IL-6 to promote cell cycling.

Antibodies, Monoclonal↗