RESUMO
A plethora of myeloma growth factors (MGFs) has been identified, but their relative importance and cooperation have not been determined. We investigated 5 MGFs (interleukin-6 [IL-6], insulin-like growth factor type 1 [IGF-1], hepatocyte growth factor [HGF], HB-epidermal growth factor [HB-EGF], and a proliferation-inducing ligand [APRIL]) in serum-free cultures of human myeloma cell lines (HMCLs). In CD45(-) HMCLs, an autocrine IGF-1 loop promoted autonomous survival whereas CD45(+) HMCLs could not survive without addition of MGFs, mainly IGF-1 and IL-6. IGF-1 was the major one: its activity was abrogated by an IGF-1R inhibitor only, whereas IL-6, HGF, or HB-EGF activity was inhibited by both IGF-1R- and receptor-specific inhibition. APRIL activity was inhibited by its specific inhibitor only. Of the investigated MGFs and their receptors, only expressions of IGF-1R and IL-6R in multiple myeloma cells (MMCs) of patients delineate a group with adverse prognosis. This is mainly explained by a strong association of IGF-1R and IL-6R expression and t(4;14) translocation, but IGF-1R expression without t(4;14) can also have a poor prognosis. Thus, IGF-1-targeted therapy, eventually in combination with anti-IL-6 therapy, could be promising in a subset of patients with MMCs expressing IGF-1R.
Assuntos
Fator de Crescimento Insulin-Like I/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Mieloma Múltiplo/patologia , Receptor IGF Tipo 1/metabolismo , Western Blotting , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular/efeitos dos fármacos , Cromossomos Humanos Par 14/genética , Cromossomos Humanos Par 4/genética , Meios de Cultura Livres de Soro , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Fator de Crescimento Semelhante a EGF de Ligação à Heparina , Fator de Crescimento de Hepatócito/farmacologia , Humanos , Immunoblotting , Técnicas Imunoenzimáticas , Hibridização in Situ Fluorescente , Interleucina-6/farmacologia , Antígenos Comuns de Leucócito/metabolismo , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Prognóstico , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptor IGF Tipo 1/genética , Receptores de Interleucina-6/genética , Receptores de Interleucina-6/metabolismo , Proteínas Recombinantes/farmacologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Translocação Genética , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/farmacologiaRESUMO
Syndecan-1 is a proteoglycan that concentrates heparin-binding factors on the surface of multiple myeloma cells, and probably plays a major role in multiple myeloma biology. As heparan sulphate and chondroitin sulphate are the bioactive components of syndecan-1, we analysed the signature of genes encoding 100 proteins involved in synthesis of these chains, i.e. from precursor uptake to post-translational modifications, using Affymetrix microarrays. The expression of enzymes required for heparan sulphate and chondroitin sulphate biosynthesis was shown to increase in parallel with syndecan-1 expression, throughout the differentiation of memory B cells into plasmablasts and normal bone marrow plasma cells. Sixteen genes were significantly different between normal and malignant plasma cells, nine of these genes -EXT2, CHSY3, CSGALNACT1, HS3ST2, HS2ST1, CHST11, CSGALNACT2, HPSE, SULF2 - encode proteins involved in glycosaminoglycan chain synthesis or modifications. Kaplan-Meier analysis was performed in two independent series of patients: B4GALT7, CSGALNACT1, HS2ST1 were associated with a good prognosis whereas EXT1 was linked to a bad prognosis. This study provides an overall picture of the major genes encoding for proteins involved in heparan sulphate and chondroitin sulphate synthesis and modifications that can be implicated in normal and malignant plasma cells.
Assuntos
Sulfatos de Condroitina/biossíntese , Perfilação da Expressão Gênica , Heparitina Sulfato/biossíntese , Mieloma Múltiplo/genética , Análise de Sequência com Séries de Oligonucleotídeos , Plasmócitos/metabolismo , Linfócitos B/metabolismo , Estudos de Casos e Controles , Linhagem Celular Tumoral , Expressão Gênica , Perfilação da Expressão Gênica/métodos , Humanos , Memória Imunológica , Estimativa de Kaplan-Meier , Mieloma Múltiplo/enzimologia , Mieloma Múltiplo/imunologia , Análise de Componente Principal , Prognóstico , Processamento de Proteína Pós-Traducional , Sindecana-1/metabolismoRESUMO
BLyS and APRIL share two receptors - transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B-cell maturation antigen (BCMA) - and BLyS binds to a third receptor, BAFF-R. We previously reported that TACI gene expression is a good indicator of a BLyS-binding receptor in human multiple myeloma cell lines (HMCLs), unlike BCMA, which is expressed by all HMCLs or BAFF-R which is typically not expressed by late-stage B cells. We hypothesised a link between APRIL and TACI through syndecan-1, similar to the situation reported for FGF and FGFR. We observed very strong binding of APRIL, but not BLyS, at the surface of all syndecan-1(+) HMCLs and primary multiple myeloma cells (MMC). All syndecan-1(+) HMCLs and MMC could also bind TACI-Fc, but not BCMA-Fc or BAFF-R-Fc molecules. Binding of APRIL or TACI-Fc was abrogated by heparin or cell pretreatment with heparitinase, which cleaves heparan sulfate chains. The growth factor activity of APRIL on MMC was also inhibited by heparin. Our data identify syndecan-1 as a co-receptor for APRIL and TACI at the cell surface of MMC, promoting the activation of an APRIL/TACI pathway that induces survival and proliferation in MMC.