RESUMEN
Multiple myeloma (MM) is an invariably fatal disease that accounts for approximately 1% to 2% of all human cancers. Surprisingly little is known about the cellular pathways contributing to growth of these tumors. Although the cytokine interleukin-6 has been suggested to be the major stimulus for myeloma cell growth, the role of a second potential growth factor, insulin-like growth factor I (IGF-I), has been less clearly defined. The IGF-I signaling cascade in 8 MM cell lines was examined. In 7 of these, the IGF-I receptor (IGF-IR) was expressed and autophosphorylated in response to ligand. Downstream of IGF-IR, insulin receptor substrate 1 was phosphorylated, leading to the activation of phosphatidylinositol-3'-kinase (PI-3K). PI-3K, in turn, regulated 2 distinct pathways. The first included Akt and Bad, leading to an inhibition of apoptosis; the second included the mitogen-activated protein kinase (MAPK), resulting in proliferation. Biologic relevance of this pathway was demonstrated because in vitro IGF-I induced both an antiapoptotic and a proliferative effect. Importantly, in vivo administration of IGF-I in SCID mice inoculated with the OPM-2 line led to approximately twice the growth rate of tumor cells as in controls. These results suggest that IGF-I activates at least 2 pathways effecting myeloma cell growth and contributes significantly to expansion of these cells in vivo. (Blood. 2000;96:2856-2861)
Asunto(s)
Factor I del Crecimiento Similar a la Insulina/fisiología , Mieloma Múltiple/fisiopatología , Proteínas de Neoplasias/fisiología , Proteínas Serina-Treonina Quinasas , Receptor IGF Tipo 1/fisiología , Transducción de Señal/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Proteínas Portadoras/fisiología , Activación Enzimática/efectos de los fármacos , Humanos , Proteínas Sustrato del Receptor de Insulina , Interleucina-6/fisiología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Ratones , Ratones SCID , Mieloma Múltiple/patología , Trasplante de Neoplasias , Fosfatidilinositol 3-Quinasas/fisiología , Fosfoproteínas/metabolismo , Fosforilación , Procesamiento Proteico-Postraduccional , Proteínas Proto-Oncogénicas/fisiología , Proteínas Proto-Oncogénicas c-akt , Células Tumorales Cultivadas/trasplante , Proteína Letal Asociada a bclRESUMEN
Biochemical abnormalities associated with the development of multiple myeloma have been difficult to define especially in terms of demonstrating an in vivo effect of suspected lesions. Herein, we have identified such a defect associated with lack of expression of PTEN, a cellular phosphatase involved in the regulation of phosphatidylinositol phosphates (PIP's). In myeloma cells, PIP's are required for phosphorylation of Akt, a key event leading to inhibition of apoptosis. Loss of PTEN results in a failure to de-phosphorylate PIP's and a corresponding increase in Akt phosphorylation. OPM-2 cells lacking PTEN expression have the highest level of Akt phosphorylation of eight lines examined. Loss of PTEN was found to be associated with a 630 bp deletion corresponding to amino acids 56 - 267. Ectopic expression of wild type PTEN in OPM-2 cells inhibited Akt phosphorylation which was correlated with an increase in apoptosis. The in vivo relevance of loss of PTEN expression was demonstrated by injecting control and wild type PTEN transfected OPM-2 cells into SCID mice. Tumors arose at an incidence of 100% in controls, but only 50% (and of smaller size and longer latency) in low PTEN expressing clones. Importantly, clones expressing high levels of PTEN failed to produce tumors even at five times the latency period of controls. These results demonstrate that PTEN deletion/mutation is responsible for in vivo growth of this tumor and suggests that PTEN regulation may play an important role in tumor development in a subset of multiple myeloma patients. Oncogene (2000) 19, 4091 - 4095
Asunto(s)
Genes Supresores de Tumor , Mieloma Múltiple/genética , Fosfatos de Fosfatidilinositol/genética , Monoéster Fosfórico Hidrolasas/genética , Proteínas Serina-Treonina Quinasas , Proteínas Supresoras de Tumor , Animales , Apoptosis , Caspasa 3 , Caspasas/metabolismo , Regulación Neoplásica de la Expresión Génica , Factor I del Crecimiento Similar a la Insulina/farmacología , Ratones , Ratones SCID , Mieloma Múltiple/metabolismo , Mieloma Múltiple/patología , Mutación , Trasplante de Neoplasias , Fosfohidrolasa PTEN , Fosfatos de Fosfatidilinositol/metabolismo , Monoéster Fosfórico Hidrolasas/deficiencia , Monoéster Fosfórico Hidrolasas/metabolismo , Fosforilación , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-akt , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Eliminación de Secuencia , Transfección , Células Tumorales CultivadasRESUMEN
Plasma cell neoplasia in humans generally occurs as multiple myeloma, an incurable form of cancer. Tumors with marked similarity can be induced in mice by a variety of agents, including chemicals, silicone, and oncogene-containing retroviruses, suggesting the use of murine tumors as an informative model to study plasma cell disease. Herein, we have focused on the role of insulin-like growth factor I receptor (IGF-IR) signaling in the development of plasma cell disease. The insulin receptor substrate 2/phosphatidylinositol 3'-kinase/p70S6K pathway was found to be either constitutively or IGF-I-dependently activated in all plasma cell tumors. Biological relevance was demonstrated in that plasma cell lines with up-regulated IGF-IR expression levels exhibited mitogenic responses to IGF-I. More importantly, expression of a dominant-negative mutant of IGF-IR in these lines strongly suppressed tumorigenesis in vivo. Taken together, these results demonstrate that up-regulation and activation of IGF-IR and the downstream signaling pathway involving insulin receptor substrate 2, phosphatidylinositol 3'-kinase, and p70S6K may play an important role in the development of a broad spectrum of plasma cell tumors.
Asunto(s)
Plasmacitoma/metabolismo , Receptor IGF Tipo 1/metabolismo , Receptor IGF Tipo 1/fisiología , Animales , Medio de Cultivo Libre de Suero , Activación Enzimática , Femenino , Immunoblotting , Proteínas Sustrato del Receptor de Insulina , Péptidos y Proteínas de Señalización Intracelular , Linfoma de Células B/metabolismo , Ratones , Ratones Endogámicos BALB C , Trasplante de Neoplasias , Neoplasias Experimentales/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Fosfoproteínas/metabolismo , Fosforilación , Plasmacitoma/inducido químicamente , Pruebas de Precipitina , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Proteínas Proto-Oncogénicas c-raf/metabolismo , Proteínas Quinasas S6 Ribosómicas/metabolismo , Transducción de Señal , Factores de Tiempo , Transfección , Células Tumorales Cultivadas , Regulación hacia ArribaRESUMEN
Parathyroid hormone (PTH) exerts its regulatory effects on calcium homeostasis in part by stimulating the release of calcium from the skeleton. PTH stimulates bone resorption indirectly, by inducing the production by stromal/osteoblastic cells of paracrine agents which recruit and activate the bone-resorbing cell, the osteoclast. The identity of the stromal cell/osteoblast-derived paracrine factor(s) responsible for mediating the effects of PTH on osteoclasts is uncertain. Recently, it has been demonstrated that the cytokine interleukin-6 (IL-6), which potently induces osteoclastogenesis, is produced by osteoblastic cells in response to PTH. Further, we have reported that circulating levels of IL-6 are elevated in patients with primary hyperparathyroidism, and correlate with biochemical markers of bone resorption. Thus, IL-6 may play a permissive role in PTH-induced bone resorption. In the current studies, we demonstrate that low-dose PTH infusion in rodents increased serum levels of IL-6, coincident with a rise in biochemical markers of bone resorption. In mice, both acute neutralization and chronic deficiency of IL-6 were associated with markedly lower levels of biochemical markers of bone resorption in response to PTH infusion than were observed in animals with normal IL-6 production. Acute neutralization of IL-6 did not affect PTH-induced changes in markers of bone formation. These findings demonstrate that PTH regulates systemic levels of IL-6 in experimental animals, that IL-6 is an important mediator of the bone-resorbing actions of PTH in vivo and suggest that IL-6 plays a role in coupling PTH-induced bone resorption and formation.
Asunto(s)
Resorción Ósea/etiología , Interleucina-6/fisiología , Hormona Paratiroidea/fisiología , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacología , Femenino , Humanos , Interleucina-6/genética , Interleucina-6/inmunología , Ratones , Ratones Noqueados/genética , Ovariectomía , Hormona Paratiroidea/farmacología , Ratas , Ratas Endogámicas , Ratas Sprague-Dawley , Valores de ReferenciaRESUMEN
All-trans retinoic acid (ATRA) is currently widely used in the therapy of acute promyelocytic leukemia and is being tested in vitro and in vivo on several other malignancies. Previously ATRA has been shown to inhibit the growth in vitro, of established human myeloma cell lines as well as cultured primary myeloma cells from patients. ATRA acts by down-regulating IL-6-receptor-alpha or gp130 on the surface of the myeloma cells. However, despite its in vitro effects on myeloma cells, ATRA therapy on advanced stage multiple myeloma (MM) patients has so far largely been ineffective. In current studies, we have assessed the efficacy of ATRA therapy against primary murine plasma cell tumors, which are an animal model for human MM. These tumors are induced at about 50% incidence in pristane-primed BALB/c mice by injection of v-raf/v-myc- containing retroviruses and are IL-6 dependent. Using this animal model, we assessed the effect of ATRA as a therapeutic agent against primary tumors at two early time points in disease development. ATRA was administered in liposomal vesicles (ATRAGEN), since liposomal-ATRA has been shown to circumvent clearance mechanisms by hepatic microsomes, which normally occur with free ATRA. In addition, ATRAGEN was previously shown to be less toxic in mice than free ATRA. ATRAGEN was administered beginning on day 25 or day 45 after virus injection and continued twice weekly for 8-11 weeks. ATRAGEN administration begun at either time point did not alter the incidence or the latency of plasma cell tumors compared with control animals. These results suggest that ATRA may not be an effective sole therapy against early MM.
Asunto(s)
Antineoplásicos/uso terapéutico , Plasmacitoma/tratamiento farmacológico , Tretinoina/uso terapéutico , Animales , Southern Blotting , Línea Celular Transformada , Femenino , Citometría de Flujo , Liposomas , Ratones , Ratones Endogámicos BALB C , Trasplante de Neoplasias , TerpenosRESUMEN
We cloned, sequenced, and mapped two divergent major histocompatibility class Ib genes from BALB/c mice. M9d and M10d both have the potential to encode full-length class I molecules, but transcripts were not readily detectable. M9 is 86% similar to M1 in its nucleotide sequence and maps next to it on YAC clones. M9 is only 64% similar to M10 and 60% to H2-K k. Probes from M10 define a new subfamily of eight class I genes in C3H mice; five cluster directly distal to H2-T1, and three are located between M9-1-7-8 and M6-4-5 in the H2-M region.
Asunto(s)
Antígenos H-2/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Mapeo Cromosómico , ADN Complementario , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido NucleicoRESUMEN
Murine plasma cell tumors share a number of common features with human multiple myeloma, suggesting their possible use as a model for this disease. However, one major difference between the two is the peritoneal localization of murine tumors as opposed to bone marrow residence of malignant plasma cells in early stages of multiple myeloma. We have thus examined the ability of murine plasmacytoma to produce disseminated growth similar to that seen in myeloma or other lymphoid neoplasias. Of four murine cell lines evaluated, all were demonstrated to effect highly metastatic disease involving multiple organs, although variation was observed between lines. A temporal analysis was accordingly performed with the S107 line to assess the pattern of cellular localization. Both light microscopy and PCR analysis revealed that engraftment of plasma cells occurs first in the bone marrow, followed by dissemination to other sites including the spleen, lung, and liver. Cells passaged in vivo through the bone marrow display an entirely different metastatic pattern with no homing preference to bone marrow or any other organ, suggesting the occurrence of a phenotypic change. Microscopic osteolytic lesions were observed adjacent to plasma cell tumor masses in the bone marrow, indicating early stages of bone disease. These findings demonstrate previously unrecognized similarities between the murine and human diseases and suggest the use of this in vivo model for experimental approaches to the treatment of human disease.
Asunto(s)
Mieloma Múltiple/patología , Plasmacitoma/patología , Animales , Biomarcadores de Tumor/análisis , Médula Ósea/patología , Humanos , Cadenas Pesadas de Inmunoglobulina/análisis , Cadenas Pesadas de Inmunoglobulina/genética , Inyecciones Intraperitoneales , Ratones , Ratones Endogámicos BALB C , Proteínas de Mieloma/análisis , Proteínas de Mieloma/genética , Metástasis de la Neoplasia , Trasplante de Neoplasias , Especificidad de Órganos , Cavidad Peritoneal/patología , Células Plasmáticas/patología , Reacción en Cadena de la Polimerasa , Especificidad de la Especie , Células Tumorales CultivadasRESUMEN
A number of studies have demonstrated that inoculation of certain types of cancer cells engineered for expression of the interleukin-2 (IL-2) gene results in reduced tumorigenicity and/or protection from subsequent challenge with a tumorigenic dose of wild-type cells. In the current studies, we have employed murine plasma cell tumors to examine IL-2-mediated tumor rejection as a possible model for therapeutic approaches to human myeloma or plasma cell leukemia. Two murine plasma cell tumor lines, S107 and X24, were infected with a retroviral vector expressing the human IL-2 gene, and the antitumor potential of IL-2-expressing infectants was characterized in syngeneic BALB/c and BALB/c nu/nu mice. Results demonstrate that tumorigenicity of both lines correlates inversely with the amount of IL-2 produced by the tumor cells. However, there are clear differences between the two lines in terms of reduced tumorigenicity and the ability to protect against co-injected parental tumor cells that appear unrelated to IL-2 levels. More importantly, intravenous immunization of animals with irradiated, IL-2 secreting cells from either line leads to significant protection from challenge with highly metastatic parental cells. These results suggest that such an approach may warrant consideration in the treatment of human plasma cell dyscrasias.
Asunto(s)
Terapia Genética , Inmunoterapia , Interleucina-2/uso terapéutico , Mieloma Múltiple/terapia , Animales , División Celular/efectos de los fármacos , Femenino , Técnicas de Transferencia de Gen , Vectores Genéticos , Interleucina-2/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Mieloma Múltiple/metabolismo , Mieloma Múltiple/patología , Retroviridae/genética , Células Tumorales CultivadasRESUMEN
BALB/c peritoneal plasmacytomas induced by a variety of agents are invariably associated with a c-myc translocation. In contrast, naturally arising bone marrow plasma cell tumors in C57BL/KaLwRij mice lack this translocation. This difference has led to the suggestion that these are 2 fundamentally different plasma cell diseases. Herein, we have analyzed 2 rare C57BL/6 peritoneal plasmacytomas in terms of characteristics associated with the bone marrow-derived lines. Like the bone marrow lines, these peritoneal plasmacytomas do not exhibit c-myc translocations, indicating that c-myc translocation is not an obligatory event in the development of all murine extramedullary plasmacytomas. However, myc is dysregulated at the mRNA level, indicating that myc overexpression may be fundamental to most plasma cell diseases but that dysregulation can occur by alternative mechanisms possibly reflecting different genetic backgrounds.
Asunto(s)
Genes myc/genética , Metástasis de la Neoplasia/genética , Neoplasias Peritoneales/genética , Plasmacitoma/genética , Animales , Northern Blotting , Médula Ósea/metabolismo , Hibridación in Situ , Inyecciones Intraperitoneales , Inyecciones Subcutáneas , Hígado/metabolismo , Pulmón/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Trasplante de Neoplasias , Bazo/metabolismo , Distribución Tisular , Translocación GenéticaRESUMEN
Plasmacytomas induced in BALB/c mice by pristane consistently evidence chromosomal translocations involving the c-myc gene and one of the Ig loci. This observation has lead to the suggestion that c-myc deregulation is a critical event in the generation of such tumors. However, it is not clear whether c-myc translocation is related to pristane treatment or occurs in normal lymphocyte populations nor whether such translocations occur normally, and at similar frequencies, in strains genetically resistant to plasmacytoma development, such as DBA/2. In order to address these questions, a Long Distance PCR assay with single copy sensitivity was employed to assess the frequency of c-myc/IgA translocations in normal and immunized mice of both plasmacytoma resistant and susceptible lineages in the absence of pristane treatment. Our data demonstrate that spontaneous translocations occur in normal DBA/2 and BALB/c mice with no significant differences in frequency. A 3-5-fold increase in translocation frequency was observed in mice immunized with cholera toxin, a strong stimulator of IgA responses. We conclude that c-myc deregulation by chromosomal translocation is associated with normal physiological processes of B-cell differentiation and, as such, can not be the determining factor leading to malignancy.
Asunto(s)
Genes myc , Plasmacitoma/genética , Plasmacitoma/inmunología , Translocación Genética , Animales , Secuencia de Bases , Toxina del Cólera/inmunología , Femenino , Predisposición Genética a la Enfermedad , Inmunización , Inmunoglobulina A/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos DBA , Datos de Secuencia MolecularRESUMEN
Frizzled polypeptides are integral membrane proteins that recently were shown to function as receptors for Wnt signaling molecules. Here, we report the identification of a novel, secreted 36-kDa protein that contains a region homologous to a putative Wnt-binding domain of Frizzleds. This protein, called Frizzled-related protein (FRP), was first identified as a heparin-binding polypeptide that copurified with hepatocyte growth factor/scatter factor in conditioned medium from a human embryonic lung fibroblast line. Degenerate oligonucleotides, based on the NH2-terminal sequence of the purified protein, were used to isolate corresponding cDNA clones. These encoded a 313-amino acid polypeptide, containing a cysteine-rich domain of approximately 110 residues that was 30-40% identical to the putative ligand-binding domain of Frizzled proteins. A 4.4-kb transcript of the FRP gene is present in many organs, both in the adult and during embryogenesis, and homologs of the gene are detectable in DNA from several vertebrate species. In biosynthetic studies, FRP was secreted but, like Wnts, tended to remain associated with cells. When coexpressed with several Wnt family members in early Xenopus embryos, FRP antagonized Wnt-dependent duplication of the embryonic dorsal axis. These results indicate that FRP may function as an inhibitor of Wnt action during development and in the adult.
Asunto(s)
Proteínas de Drosophila , Heparina/metabolismo , Proteínas de la Membrana/genética , Proteínas/aislamiento & purificación , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas de Pez Cebra , Secuencia de Aminoácidos , Animales , Línea Celular , Clonación Molecular , Receptores Frizzled , Humanos , Datos de Secuencia Molecular , Proteínas/genética , Proteínas/metabolismo , Receptores Acoplados a Proteínas G , Alineación de Secuencia , Proteínas Wnt , XenopusRESUMEN
Acute exposure of mammals to the environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) results in a diverse set of toxicologic and pathologic effects. The mechanism of some of these effects has been studied extensively in vitro and correlative studies have indicated the involvement of a transcription factor known as the aryl hydrocarbon receptor (AHR). However, a definitive association of the AHR with TCDD-mediated toxicity has been difficult to establish due to the diversity of effects and the ubiquitous expression of this receptor. In an effort to distinguish AHR-mediated TCDD toxicities from those resulting from alternative pathways, we have made use of the recently described AHR-deficient mouse that was generated by locus-specific homologous recombination in embryonic stem cells. Present studies demonstrate that AHR-deficient mice are relatively unaffected by doses of TCDD (2000 micrograms/kg) 10-fold higher than that found to induce severe toxic and pathologic effects in littermates expressing a functional AHR. Analyses of liver, thymus, heart, kidney, pancreas, spleen, lymph nodes, and uterus from AHR-deficient mice identified no significant TCDD-induced lesions. The resistance of AHR-deficient mice to TCDD-induced thymic atrophy appears restricted to processes involving AHR since the corticosteroid dexamethasone rapidly and efficiently induced cortical depletion in both AHR-deficient and normal littermate control mice. Taken together these results suggest that the pathological changes induced by TCDD in the liver and thymus are mediated entirely by the AHR. However, it is important to note that at high doses of TCDD, AHR-deficient mice displayed limited vasculitis and scattered single cell necrosis in their lungs and livers, respectively. The mechanism(s) responsible for these apparently receptor-independent processes remain unclear but may involve novel, alternative pathways for TCDD-induced toxicity.
Asunto(s)
Dibenzodioxinas Policloradas/toxicidad , Receptores de Hidrocarburo de Aril/deficiencia , Timo/efectos de los fármacos , Animales , Dexametasona/uso terapéutico , Femenino , Inyecciones Intraperitoneales , Hígado/efectos de los fármacos , Hígado/patología , Pulmón/efectos de los fármacos , Pulmón/patología , Ratones , Ratones Noqueados , Tamaño de los Órganos/efectos de los fármacos , Timo/patologíaRESUMEN
The development of murine plasma cell tumors induced by raf/myc containing retroviruses is facilitated by T cells and completely dependent on IL-6. To determine whether kinases with differing specificities reflect alternative biochemical pathways in B cell tumorigenesis, we have employed an abl/myc containing retrovirus to assess neoplastic development. In contrast with raf/myc, abl/myc disease is T cell and IL-6 independent. An examination of the IL-6 signal transduction pathway reveals that this pathway, as defined by activation of Stat3, is inducible by IL-6 in raf/myc tumors but constitutively activated in abl/myc tumors. These findings provide a mechanism for the derivation of cytokine-independent plasma cell tumors and suggest that both IL-6-dependent and independent tumors may arise in vivo depending on the particular mutational events incurred during tumorigenesis.
Asunto(s)
Genes abl/inmunología , Interleucina-6/inmunología , Plasmacitoma/genética , Infecciones por Retroviridae/genética , Transducción de Señal/genética , Transducción de Señal/inmunología , Infecciones Tumorales por Virus/genética , Animales , Secuencia de Bases , Interleucina-6/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos DBA , Ratones Desnudos , Datos de Secuencia Molecular , Fenotipo , Plasmacitoma/inmunología , Infecciones por Retroviridae/inmunología , Infecciones Tumorales por Virus/inmunologíaRESUMEN
H2-M1 is a non-classical major histocompatibility complex (MHC) class I gene that is highly divergent from classical class I genes; M1 was the first gene in the recently classified M region of the mouse MHC to be cloned. Although the M1 DNA sequence contains normal splice sites, open reading frames within its exons, and a recognizable promoter, no M1 transcripts were detected in various healthy mouse tissues. However, M1 transcripts were detected in transfected L cells and in vivo in brains of M1 transgenic mice, albeit at very low levels, and the level of expression is correlated with transgene copy number. Analysis of the M1 promoter region identified a competent promoter capable of directing transcription, but whose expression is repressed by two strong upstream silencer elements, one mapping between -184 base pairs (bp) and -266 bp and the other between -1149 bp and -1702 bp. These studies suggest that M1 expression is highly regulated and restricted either temporally or to a very limited number of cell types.
Asunto(s)
Genes MHC Clase I/genética , Secuencias Reguladoras de Ácidos Nucleicos , Animales , Secuencia de Bases , Northern Blotting , Química Encefálica , Exones , Células L , Ratones , Ratones Transgénicos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , ARN/genética , Transcripción Genética , TransfecciónRESUMEN
Interleukin (IL) 6 has been suggested to be the major cytokine responsible for proliferation of neoplastic plasma cells in both human myeloma and mouse plasmacytoma. Much of the evidence supporting this suggestion is derived from in vitro studies in which the survival or proliferation of some plasma cell tumors has been found to be IL-6 dependent. However, it remains unclear whether this dependency is the consequence of in vivo or in vitro selective pressures that preferentially expand IL-6-responsive tumor cells, or whether it reflects a critical in vivo role for IL-6 in plasma cell neoplasia. To address this question, we have attempted to induce plasma cell tumors in normal mice and in IL-6-deficient mice generated by introduction of a germline-encoded null mutation in the IL-6 gene. The results demonstrate that mice homozygous (+/+) or heterozygous (+/-) for the wild-type IL-6 allele yield the expected incidences of plasma cell tumors. In contrast, mice homozygous for the IL-6-null allele (-/-) are completely resistant to plasma cell tumor development. These studies define the essential role of IL-6 in the development of B lineage tumors in vivo and provide experimental support for continued efforts to modulate this cytokine in the treatment of appropriate human B cell malignancies.
Asunto(s)
Linfocitos B/fisiología , Interleucina-6/fisiología , Mieloma Múltiple/fisiopatología , Plasmacitoma/fisiopatología , Alelos , Animales , Secuencia de Bases , División Celular , Cocarcinogénesis , Cruzamientos Genéticos , Femenino , Citometría de Flujo , Gammaretrovirus/genética , Gammaretrovirus/fisiología , Predisposición Genética a la Enfermedad , Genotipo , Hibridación in Situ , Interleucina-6/deficiencia , Interleucina-6/genética , Linfoma de Células B/etiología , Linfoma de Células B/fisiopatología , Linfoma de Células T/etiología , Linfoma de Células T/fisiopatología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos , Ratones Noqueados , Datos de Secuencia Molecular , Mieloma Múltiple/etiología , Trasplante de Neoplasias , Oncogenes , Plasmacitoma/etiología , Reacción en Cadena de la Polimerasa , Terpenos/toxicidad , Infecciones Tumorales por Virus/virologíaRESUMEN
The aryl hydrocarbon (Ah) receptor (AHR) mediates many carcinogenic and teratogenic effects of environmentally toxic chemicals such as dioxin. An AHR-deficient (Ahr-/-) mouse line was constructed by homologous recombination in embryonic stem cells. Almost half of the mice died shortly after birth, whereas survivors reached maturity and were fertile. The Ahr-/- mice showed decreased accumulation of lymphocytes in the spleen and lymph nodes, but not in the thymus. The livers of Ahr-/- mice were reduced in size by 50 percent and showed bile duct fibrosis Ahr-/- mice were also nonresponsive with regard to dioxin-mediated induction of genes encoding enzymes that catalyze the metabolism of foreign compounds. Thus, the AHR plays an important role in the development of the liver and the immune system.
Asunto(s)
Inmunidad/fisiología , Hígado/fisiología , Receptores de Hidrocarburo de Aril/fisiología , Animales , Femenino , Regulación de la Expresión Génica/fisiología , Cirrosis Hepática Experimental/genética , Cirrosis Hepática Experimental/patología , Tejido Linfoide/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Hidrocarburo de Aril/genéticaRESUMEN
Major interest in the analysis of mature plasma cell neoplasias of mice and humans has focused on identification of precursor cells that give rise to mature malignant plasma cells. Although several laboratories have recently suggested that such cells are present in the granulomas of pristane-treated mice and the bone marrow of some multiple myeloma patients, the in vivo cellular interactions required for their differentiation into mature plasma cell tumors remains unclear. Given the extensive interactions of peripheral T cells and normal B cells, we assessed the potential role of T cells in plasma-cell tumor development, by using a myc, raf-containing retrovirus, J3V1, to induce plasmacytomas in normal BALB/c mice, T-cell-deficient nude mice, and T-cell-reconstituted nude mice. The B-lineage tumors arising in normal BALB/c mice were uniformly mature plasmacytomas, most of which secreted immunoglobulin. In contrast, nude mice yielded predominantly non-immunoglobulin-secreting B-cell lymphomas with a phenotype characteristic of peripheral B cells. T-cell reconstitution of nude mice prior to tumor induction resulted in a shift from B-cell lymphomas to plasmacytomas. These results imply that transformation can occur prior to terminal differentiation of B cells and that such transformed cells can be driven to terminal differentiation by peripheral T cells. These findings further suggest that, in human multiple myeloma, the ability of T cells to influence the differentiation state of transformed B cells may provide a mechanism by which malignant plasma cells found in the bone marrow could arise from clonotypically related less-mature B cells found in both the bone marrow and periphery.
Asunto(s)
Linfocitos B/patología , Transformación Celular Neoplásica , Plasmacitoma/patología , Linfocitos T/fisiología , Animales , Diferenciación Celular , Femenino , Humanos , Inmunocompetencia , Inmunoglobulinas/metabolismo , Linfoma de Células B/genética , Linfoma de Células B/patología , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Plasmacitoma/genética , Polimorfismo de Longitud del Fragmento de Restricción , RetroviridaeRESUMEN
Peyer's patch, peripheral lymph node, and mesenteric lymph node cells were transferred to immunodeficient SCID mice to assess the long-term (150-300 days) potential of these cells to repopulate the host's immune system. Results demonstrate that, irrespective of donor population, total serum Ig and isotype distribution appear normal within 4 weeks of reconstitution and remain at normal levels for up to one year following cell transfer. At the cellular level, each donor population reconstitutes splenic T and B cell compartments in a progressive and quantitatively indistinguishable manner. Immunohistological analyses of reconstituted mice indicate that, although some qualitative differences are evident, normal splenic composition and architecture are observed. In contrast, gut reconstitution varies significantly with donor population. Peyer's patch cells yield normal-appearing gut tissue with extensive infiltration of the lamina propria and intraepithelial compartments by T cells and IgA-secreting plasma cells. Peripheral lymph node cells give rise to T cells found almost exclusively in the lamina propria, while IgA secreting plasma cells are rarely detected. The course and extent of reconstitution further suggest that all donor populations contain long-lived T and B cells as well as self-renewing lymphocytes capable of extensive expansion. This latter observation has potentially important implications for both transplantation biology and gene therapy applications.
Asunto(s)
Linfocitos B/fisiología , Inmunoterapia Adoptiva , Mucosa Intestinal/inmunología , Ganglios Linfáticos/inmunología , Ganglios Linfáticos Agregados/inmunología , Inmunodeficiencia Combinada Grave/inmunología , Linfocitos T/fisiología , Animales , Femenino , Citometría de Flujo , Técnicas para Inmunoenzimas , Inmunoglobulina A/análisis , Inmunoglobulina G/análisis , Isotipos de Inmunoglobulinas/análisis , Inmunofenotipificación , Ratones , Ratones Endogámicos DBA , Ratones SCID , Bazo/inmunologíaRESUMEN
Significant immigration of peripheral T cells into SCID thymus was observed following reconstitution with normal Peyer's patch, mesenteric lymph node or peripheral lymph node cells. Immunohistologic and flow cytometric analyses reveal that T cells from these tissues are found in the thymus for as long as 177 days and can account for up to 67% of intrathymic cells. The returning cells express the CD3/T cell receptor alpha/beta complex, indicative of mature cells, and are equally divided among helper (CD4+CD8-) and cytotoxic (CD4-/CD8+) phenotypes. The immigration of peripheral T cells is not accompanied by the appearance of immature, double-positive (CD4+CD8+) thymocytes as seen in similar reconstitutions using bone marrow. Taken together, these results suggest that peripheral T cells from a variety of lymphoid organs may regularly re-enter the thymus and, thus, possibly play a role in normal thymic development.
Asunto(s)
Inmunodeficiencia Combinada Grave/inmunología , Subgrupos de Linfocitos T/inmunología , Timo/inmunología , Animales , Antígenos CD4/metabolismo , Antígenos CD8/metabolismo , Diferenciación Celular , Movimiento Celular/inmunología , Femenino , Ganglios Linfáticos/citología , Ganglios Linfáticos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos DBA , Ratones SCID , Ganglios Linfáticos Agregados/citología , Ganglios Linfáticos Agregados/inmunología , Fenotipo , Inmunodeficiencia Combinada Grave/patología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/trasplante , Timo/citologíaRESUMEN
To date much is known about the genetics of susceptibility and resistance to plasmacytoma induction in mice, however little is known about the cellular aspects of these phenotypes. The complexity of plasmacytomagenesis allows for susceptibility and resistance to reflect differences in B cells, T cells, accessory cells and/or stromal elements contributing to the disease process. Alternatively, these phenotypes may result from differential abilities to affect events critical to plasmacytomagenesis, such as myc deregulation. To address these possibilities, the v-myc-raf-containing retrovirus, J3V1, was used to induce plasmacytomas (PCTs) in severe combined immunodeficient (SCID) mice reconstituted with susceptible (Balb/c) and/or resistant (DBA/2) cells. The results demonstrate that Balb/c bone marrow (BM)-reconstituted SCID mice yielded PCTs of donor origin, while DBA/2 BM-reconstituted mice did not. Mice reconstituted with both DBA/2 BM and Balb/c peripheral lymphocytes, as well as those reconstituted with Balb/c peripheral lymphocytes alone, also yielded only Balb/c PCTs. These results indicate that: (1) a microenvironment supportive of plasmacytomagenesis is insufficient to allow PCT development among resistant cells; (2) DBA/2 BM-derived cells do not suppress plasmacytomagenesis by target cell elimination or microenvironment destruction; (3) resistance is not solely attributable to the inability of DBA/2 B cells to deregulate myc; and (4) potential PCT targets reside in a number of lymphoid tissues. Taken together, these results demonstrate that a major aspect of resistance/susceptibility to plasmacytomagenesis is dictated by the genotype of the target B cell.