RESUMEN
BACKGROUND: Multiple myeloma (MM) is a malignancy of plasma cells that arises from premalignant Monoclonal Gammopathy of Undetermined Significance (MGUS) and often progresses through an asymptomatic Smoldering (SMM) phase. Understanding the interactions between abnormal clonal plasma cells and the tumor microenvironment (TME) in the early disease states (MGUS, SMM) may inform risk assessment and therapy. PATIENTS AND METHODS: We performed high dimensional immunologic analysis of bone marrow specimens from 73 subjects with SMM by mass cytometry and T cell receptor sequencing of CD138-depleted bone marrow (BM) mononuclear cells, and proteomics and seromic profiling of BM plasma. Analysis of individual assay data identified self-organizing subgroups of SMM patients. We then applied novel bioinformatic methods to integrate data from pairs, trios, and quartets of assays. RESULTS: Mass cytometry, TCRSeq and proteomics identified three taxa (sing. taxon) of subjects that shared common characteristics across all three assays. Differential levels of BM plasma pleiotropin (PTN) and BM T cells and their productive clonality emerged as strong distinguishing factors among these taxa. CONCLUSION: These results suggest that the continuum from MGUS to MM does not consist of a single pathway in the TME, and that complex interactions between myeloma cells and the TME may ultimately determine progression and inform clinical management.
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Gammopatía Monoclonal de Relevancia Indeterminada , Mieloma Múltiple , Mieloma Múltiple Quiescente , Humanos , Microambiente Tumoral , Gammopatía Monoclonal de Relevancia Indeterminada/patología , Mieloma Múltiple/patología , Células Plasmáticas/patología , Progresión de la EnfermedadRESUMEN
BACKGROUND: Teclistamab (JNJ-64007957), a B-cell maturation antigen × CD3 bispecific antibody, displayed potent T-cell-mediated cytotoxicity of multiple myeloma cells in preclinical studies. OBJECTIVE: A first-in-human, Phase I, dose escalation study (MajesTEC-1) is evaluating teclistamab in patients with relapsed/refractory multiple myeloma. PATIENTS AND METHODS: To estimate the efficacious therapeutic dosing range of teclistamab, pharmacokinetic (PK) data following the first cycle doses in the low-dose cohorts in the Phase I study were modeled using a 2-compartment model and simulated to predict the doses that would have average and trough serum teclistamab concentrations in the expected therapeutic range (between EC50 and EC90 values from an ex vivo cytotoxicity assay). RESULTS: The doses predicted to have average serum concentrations between the EC50 and EC90 range were validated. In addition, simulations showed that weekly intravenous and subcutaneous doses of 0.70 mg/kg and 0.72 mg/kg, respectively, resulted in mean trough levels comparable to the maximum EC90. The most active doses in the Phase I study were weekly intravenous doses of 0.27 and 0.72 mg/kg and weekly subcutaneous doses of 0.72 and 1.5 mg/kg, with the weekly 1.5 mg/kg subcutaneous doses selected as the recommended Phase II dose (RP2D). With active doses, exposure was maintained above the mean EC90. All patients who responded to the RP2D of teclistamab had exposure above the maximum EC90 in both serum and bone marrow on cycle 3, Day 1 of treatment. CONCLUSIONS: Our findings show that PK simulations of early clinical data together with ex vivo cytotoxicity estimates can inform the identification of a bispecific antibody's therapeutic range. CLINICAL TRIAL REGISTRATION: NCT03145181, date of registration: May 9, 2017.
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Antineoplásicos , Mieloma Múltiple , Administración Intravenosa , Antineoplásicos/uso terapéutico , Antígeno de Maduración de Linfocitos B , Humanos , Mieloma Múltiple/tratamiento farmacológicoRESUMEN
T-cell redirecting bispecific antibodies hold high promise for treatment of B-cell malignancies. B-cell maturation antigen (BCMA) exhibits high expression on normal and malignant mature B cells including plasma cells, which can be enhanced by inhibition of γ-secretase. BCMA is considered a validated target in multiple myeloma but whether mature B-cell lymphomas can be targeted by the BCMAxCD3 T-cell redirector teclistamab is currently unknown. BCMA expression on B-cell non-Hodgkin lymphoma and primary chronic lymphocytic leukemia (CLL) cells was assessed by flow cytometry and/or IHC. To assess teclistamab efficacy, cells were treated with teclistamab in presence of effector cells with/without γ-secretase inhibition. BCMA could be detected on all tested mature B-cell malignancy cell lines, while expression levels varied per tumor type. γ-secretase inhibition universally increased BCMA surface expression. These data were corroborated in primary samples from patients with Waldenstrom's macroglobulinemia, CLL, and diffuse large B-cell lymphoma. Functional studies with the B-cell lymphoma cell lines revealed teclistamab-mediated T-cell activation, proliferation, and cytotoxicity. This was independent of the level of BCMA expression, but generally lower in mature B-cell malignancies compared with multiple myeloma. Despite low BCMA levels, healthy donor T cells and CLL-derived T cells induced lysis of (autologous) CLL cells upon addition of teclistamab. These data show that BCMA is expressed on various B-cell malignancies and that lymphoma cell lines and primary CLL can be targeted using teclistamab. Further studies to understand the determinants of response to teclistamab are required to identify which other diseases might be suitable for teclistamab targeting. Significance: Besides reported BCMA expression on multiple myeloma, we demonstrate BCMA can be detected and enhanced using γ-secretase inhibition on cell lines and primary material of various B-cell malignancies. Furthermore, using CLL we demonstrate that low BCMA-expressing tumors can be targeted efficiently using the BCMAxCD3 DuoBody teclistamab.
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Anticuerpos Biespecíficos , Antineoplásicos , Leucemia Linfocítica Crónica de Células B , Linfoma de Células B , Mieloma Múltiple , Humanos , Secretasas de la Proteína Precursora del Amiloide , Anticuerpos Biespecíficos/farmacología , Anticuerpos Biespecíficos/uso terapéutico , Antígeno de Maduración de Linfocitos B , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Linfoma de Células B/tratamiento farmacológico , Linfocitos TRESUMEN
Cell surface expression levels of GPRC5D, an orphan G protein-coupled receptor, are significantly higher on multiple myeloma (MM) cells, compared with normal plasma cells or other immune cells, which renders it a promising target for immunotherapeutic strategies. The novel GPRC5D-targeting T-cell redirecting bispecific antibody, talquetamab, effectively kills GPRC5D+ MM cell lines in the presence of T cells from both healthy donors or heavily pretreated MM patients. In addition, talquetamab has potent anti-MM activity in bone marrow (BM) samples from 45 patients, including those with high-risk cytogenetic aberrations. There was no difference in talquetamab-mediated killing of MM cells from newly diagnosed, daratumumab-naïve relapsed/refractory (median of 3 prior therapies), and daratumumab-refractory (median of 6 prior therapies) MM patients. Tumor cell lysis was accompanied by T-cell activation and degranulation, as well as production of pro-inflammatory cytokines. High levels of GPRC5D and high effector:target ratio were associated with improved talquetamab-mediated lysis of MM cells, whereas an increased proportion of T cells expressing PD-1 or HLA-DR, and elevated regulatory T-cell (Treg) counts were associated with suboptimal killing. In cell line experiments, addition of Tregs to effector cells decreased MM cell lysis. Direct contact with bone marrow stromal cells also impaired the efficacy of talquetamab. Combination therapy with daratumumab or pomalidomide enhanced talquetamab-mediated lysis of primary MM cells in an additive fashion. In conclusion, we show that the GPRC5D-targeting T-cell redirecting bispecific antibody talquetamab is a promising novel antimyeloma agent. These results provide the preclinical rationale for ongoing studies with talquetamab in relapsed/refractory MM.
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Anticuerpos Biespecíficos , Mieloma Múltiple , Anticuerpos Biespecíficos/farmacología , Anticuerpos Biespecíficos/uso terapéutico , Humanos , Activación de Linfocitos , Mieloma Múltiple/tratamiento farmacológico , Linfocitos T ReguladoresRESUMEN
CD38-targeted antibody, daratumumab, is approved for the treatment of multiple myeloma (MM). Phase 1/2 studies GEN501/SIRIUS revealed a novel immunomodulatory mechanism of action (MOA) of daratumumab that enhanced the immune response, reducing natural killer (NK) cells without affecting efficacy or safety. We further evaluated daratumumab's effects on immune cells in whole blood samples of relapsed/refractory MM patients from both treatment arms of the phase 3 POLLUX study (lenalidomide/dexamethasone [Rd] or daratumumab plus Rd [D-Rd]) at baseline (D-Rd, 40; Rd, 45) and after 2 months on treatment (D-Rd, 31; Rd, 33) using cytometry by time-of-flight. We confirmed previous reports of NK cell reduction with D-Rd. Persisting NK cells were phenotypically distinct, with increased expression of HLA-DR, CD69, CD127, and CD27. The proportion of T cells increased preferentially in deep responders to D-Rd, with a higher proportion of CD8+ versus CD4+ T cells. The expansion of CD8+ T cells correlated with clonality, indicating generation of adaptive immune response with D-Rd. D-Rd resulted in a higher proportion of effector memory T cells versus Rd. D-Rd reduced immunosuppressive CD38+ regulatory T cells. This study confirms daratumumab's immunomodulatory MOA in combination with immunomodulatory drugs and provides further insight into immune cell changes and activation status following daratumumab-based therapy.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biomarcadores/análisis , Células Asesinas Naturales/inmunología , Mieloma Múltiple/inmunología , Linfocitos T Reguladores/inmunología , Linfocitos T/inmunología , Anticuerpos Monoclonales/administración & dosificación , Dexametasona/administración & dosificación , Humanos , Células Asesinas Naturales/efectos de los fármacos , Lenalidomida/administración & dosificación , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/patología , Linfocitos T/efectos de los fármacos , Linfocitos T Reguladores/efectos de los fármacosRESUMEN
Acute myeloid leukemia (AML) is the most common acute leukemia in adults, with approximately four new cases per 100,000 persons per year. Standard treatment for AML consists of induction chemotherapy with remission achieved in 50 to 75% of cases. Unfortunately, most patients will relapse and die from their disease, as 5-y survival is roughly 29%. Therefore, other treatment options are urgently needed. In recent years, immune-based therapies have led to unprecedented rates of survival among patients with some advanced cancers. Suppression of T cell function in the tumor microenvironment is commonly observed and may play a role in AML. We found that there is a significant association between T cell infiltration in the bone marrow microenvironment of newly diagnosed patients with AML and increased overall survival. Functional studies aimed at establishing the degree of T cell suppression in patients with AML revealed impaired T cell function in many patients. In most cases, T cell proliferation could be restored by blocking the immune checkpoint molecules PD-1, CTLA-4, or TIM3. Our data demonstrate that AML establishes an immune suppressive environment in the bone marrow, in part through T cell checkpoint function.
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Médula Ósea/metabolismo , Leucemia Mieloide Aguda/metabolismo , Linfocitos T/metabolismo , Microambiente Tumoral/fisiología , Médula Ósea/inmunología , Antígeno CTLA-4/metabolismo , Proliferación Celular , Citocinas/metabolismo , Receptor 2 Celular del Virus de la Hepatitis A/metabolismo , Humanos , Leucemia Mieloide Aguda/inmunología , Leucemia Mieloide Aguda/terapia , Receptor de Muerte Celular Programada 1/metabolismo , Linfocitos T/inmunologíaRESUMEN
BACKGROUND: Study populations in clinical research must reflect US changing demographics, especially with the rise of precision medicine. However, racial and ethnic minority groups (REMGs) have low rates of participation in cancer clinical trials. METHODS: Criteria were developed to identify cancer centers able to accrue a higher than average proportion of REMGs into clinical trials. Comprehensive interviews were conducted with leaders of these cancer centers to identify operational strategies contributing to enhanced accrual of REMGs. RESULTS: Eight US cancer centers reported a REMG accrual rate range in cancer research between 10 and 50% in a 12-month reporting period and met other criteria for inclusion. Fourteen leaders participated in this assessment. Key findings were that centers: had a metric collection and reporting approach; routinely captured race and ethnicity data within databases accessible to research staff; had operational standards to support access and inclusion; developed practices to facilitate sustained patient participation during clinical trials; had strategies to decrease recruitment time and optimize clinical study design; and identified low-resource strategies for REMG accrual. There was also a clear commitment to establish processes that support the patient's provider as the key influencer of patient recruitment into clinical trials. CONCLUSION: We have identified operational practices that facilitate increased inclusion of REMGs in cancer trials. In order to establish a sustainable cancer center inclusion research strategy, it is valuable to include an operational framework that is informed by leading US cancer centers of excellence.
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PURPOSE: Multiple myeloma (MM) patients with disease refractory to all available drugs have a poor outcome, indicating the need for new agents with novel mechanisms of action. EXPERIMENTAL DESIGN: We evaluated the anti-MM activity of the fully human BCMA×CD3 bispecific antibody JNJ-7957 in cell lines and bone marrow (BM) samples. The impact of several tumor- and host-related factors on sensitivity to JNJ-7957 therapy was also evaluated. RESULTS: We show that JNJ-7957 has potent activity against 4 MM cell lines, against tumor cells in 48 of 49 BM samples obtained from MM patients, and in 5 of 6 BM samples obtained from primary plasma cell leukemia patients. JNJ-7957 activity was significantly enhanced in patients with prior daratumumab treatment, which was partially due to enhanced killing capacity of daratumumab-exposed effector cells. BCMA expression did not affect activity of JNJ-7957. High T-cell frequencies and high effector:target ratios were associated with improved JNJ-7957-mediated lysis of MM cells. The PD-1/PD-L1 axis had a modest negative impact on JNJ-7957 activity against tumor cells from daratumumab-naïve MM patients. Soluble BCMA impaired the ability of JNJ-7957 to kill MM cells, although higher concentrations were able to overcome this negative effect. CONCLUSIONS: JNJ-7957 effectively kills MM cells ex vivo, including those from heavily pretreated MM patients, whereby several components of the immunosuppressive BM microenvironment had only modest effects on its killing capacity. Our findings support the ongoing trial with JNJ-7957 as single agent and provide the preclinical rationale for evaluating JNJ-7957 in combination with daratumumab in MM.
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Anticuerpos Biespecíficos/farmacología , Anticuerpos Monoclonales/farmacología , Antígeno de Maduración de Linfocitos B/inmunología , Complejo CD3/inmunología , Mieloma Múltiple/tratamiento farmacológico , Anticuerpos Biespecíficos/inmunología , Citotoxicidad Celular Dependiente de Anticuerpos , Antineoplásicos/farmacología , Médula Ósea/patología , Evaluación Preclínica de Medicamentos , Sinergismo Farmacológico , Quimioterapia Combinada , Humanos , Inmunoterapia/métodos , Mieloma Múltiple/inmunología , Mieloma Múltiple/metabolismo , Mieloma Múltiple/patología , Células Tumorales CultivadasRESUMEN
PURPOSE: Participation of racial and ethnic minority groups (REMGs) in cancer trials is disproportionately low despite a high prevalence of certain cancers in REMG populations. We aimed to identify notable practices used by leading US cancer centers that facilitate REMG participation in cancer trials. METHODS: The National Minority Quality Forum and Sustainable Healthy Communities Diverse Cancer Communities Working Group developed criteria by which to identify eligible US cancer centers-REMGs comprise 10% or more of the catchment area; a 10% to 50% yearly accrual rate of REMGs in cancer trials; and the presence of formal community outreach and diversity enrollment programs. Cancer center leaders were interviewed to ascertain notable practices that facilitate REMG accrual in clinical trials. RESULTS: Eight cancer centers that met the Communities Working Group criteria were invited to participate in in-depth interviews. Notable strategies for increased REMG accrual to cancer trials were reported across five broad themes: commitment and center leadership, investigator training and mentoring, community engagement, patient engagement, and operational practices. Specific notable practices included increased engagement of health care professionals, the presence of formal processes for obtaining REMG patient/caregiver input on research projects, and engagement of community groups to drive REMG participation. Centers also reported an increase in the allocation of resources to improving health disparities and increased dedication of research staff to REMG engagement. CONCLUSION: We have identified notable practices that facilitate increased participation of REMGs in cancer trials. Wide implementation of such strategies across cancer centers is essential to ensure that all populations benefit from advances in an era of increasingly personalized treatment of cancer.
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Instituciones Oncológicas/normas , Etnicidad , Grupos Raciales , Ensayos Clínicos como Asunto , Femenino , Humanos , Masculino , Estados UnidosRESUMEN
Daratumumab is a CD38-targeted human monoclonal antibody with direct anti-myeloma cell mechanisms of action. Flow cytometry in relapsed and/or refractory multiple myeloma (RRMM) patients treated with daratumumab revealed cytotoxic T-cell expansion and reduction of immune-suppressive populations, suggesting immune modulation as an additional mechanism of action. Here, we performed an in-depth analysis of the effects of daratumumab on immune-cell subpopulations using high-dimensional mass cytometry. Whole-blood and bone-marrow baseline and on-treatment samples from RRMM patients who participated in daratumumab monotherapy studies (SIRIUS and GEN501) were evaluated with high-throughput immunophenotyping. In daratumumab-treated patients, the intensity of CD38 marker expression decreased on many immune cells in SIRIUS whole-blood samples. Natural killer (NK) cells were depleted with daratumumab, with remaining NK cells showing increased CD69 and CD127, decreased CD45RA, and trends for increased CD25, CD27, and CD137 and decreased granzyme B. Immune-suppressive population depletion paralleled previous findings, and a newly observed reduction in CD38+ basophils was seen in patients who received monotherapy. After 2 months of daratumumab, the T-cell population in whole-blood samples from responders shifted to a CD8 prevalence with higher granzyme B positivity (P = 0.017), suggesting increased killing capacity and supporting monotherapy-induced CD8+ T-cell activation. High-throughput cytometry immune profiling confirms and builds upon previous flow cytometry data, including comparable CD38 marker intensity on plasma cells, NK cells, monocytes, and B/T cells. Interestingly, a shift toward cytolytic granzyme B+ T cells was also observed and supports adaptive responses in patients that may contribute to depth of response. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.
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ADP-Ribosil Ciclasa 1/inmunología , Anticuerpos Monoclonales/uso terapéutico , Antineoplásicos/uso terapéutico , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/inmunología , Antígenos de Diferenciación de Linfocitos T/metabolismo , Basófilos/citología , Basófilos/efectos de los fármacos , Basófilos/inmunología , Células de la Médula Ósea/citología , Células de la Médula Ósea/inmunología , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/inmunología , Citometría de Flujo , Granzimas/metabolismo , Humanos , Inmunofenotipificación , Células Asesinas Naturales/citología , Mieloma Múltiple/sangre , Mieloma Múltiple/metabolismo , RecurrenciaRESUMEN
BACKGROUND: Plasmablasts and plasma cells play a key role in many autoimmune diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). This study was undertaken to evaluate the potential of targeting CD38 as a plasma cell/plasmablast depletion mechanism by daratumumab in the treatment of patients with RA and SLE. METHODS: RNA-sequencing analysis of synovial biopsies from various stages of RA disease progression, flow cytometry analysis of peripheral blood mononuclear cells (PBMC) from patients with RA or SLE and healthy donors, immunohistochemistry assessment (IHC) of synovial biopsies from patients with early RA, and ex vivo immune cell depletion assays using daratumumab (an anti-CD38 monoclonal antibody) were used to assess CD38 as a therapeutic target. RESULTS: We demonstrated that the plasma cell/plasmablast-related genes CD38, XBP1, IRF4, PRDM1, IGJ and TNFSF13B are significantly up-regulated in synovial biopsies from patients with arthralgia, undifferentiated arthritis (UA), early RA and established RA as compared to healthy controls and control patients with osteoarthritis. In addition, the highest CD38 expression was observed on plasma cells and plasmablasts compared to natural killer (NK) cells, classical dendritic cells (DCs), plasmacytoid DCs (pDCs) and T cells, in blood from healthy controls and patients with SLE and RA. Furthermore, IHC showed CD38 staining in the same region as CD3 and CD138 staining in synovial tissue biopsies from patients with early RA. Most importantly, our data show for the first time that daratumumab effectively depletes plasma cells/plasmablasts in PBMC from patients with SLE and RA in a dose-dependent manner ex vivo. CONCLUSION: These results indicate that CD38 may be a potential target for RA disease interception and daratumumab should be evaluated clinically for the treatment of both RA and SLE.
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ADP-Ribosil Ciclasa 1/antagonistas & inhibidores , Antirreumáticos/uso terapéutico , Artritis Reumatoide/tratamiento farmacológico , Lupus Eritematoso Sistémico/tratamiento farmacológico , Células Plasmáticas/metabolismo , ADP-Ribosil Ciclasa 1/genética , ADP-Ribosil Ciclasa 1/metabolismo , Adulto , Anciano , Artritis Reumatoide/genética , Artritis Reumatoide/metabolismo , Células Cultivadas , Femenino , Perfilación de la Expresión Génica/métodos , Humanos , Leucocitos Mononucleares/metabolismo , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/metabolismo , Masculino , Persona de Mediana Edad , Membrana Sinovial/metabolismo , Membrana Sinovial/patologíaRESUMEN
Daratumumab, a human CD38 imunoglobulin G 1κ monoclonal antibody, has demonstrated clinical activity and a manageable safety profile in monotherapy and combination therapy clinical trials in relapsed and/or refractory multiple myeloma. CD38 is expressed at high levels on myeloma cells and, to a lesser extent, on immune effector cells, including natural killer (NK) cells, which are important for daratumumab-mediated antibody-dependent cellular cytotoxicity (ADCC). Here, the pharmacodynamic effects of daratumumab monotherapy on NK cells, and the effect of NK cell dynamics on daratumumab efficacy and safety, were assessed. Daratumumab, like other CD38 antibodies, reduced NK-cell counts in peripheral blood mononuclear cells (PBMCs) of healthy donors in vitro. Data on NK-cell counts, clinical efficacy, and adverse events were pooled from two single-agent daratumumab studies, GEN501 and SIRIUS. In daratumumab-treated myeloma patients, total and activated NK-cell counts reduced rapidly in peripheral blood after the first dose, remained low over the course of treatment, and recovered after treatment ended. There was a clear maximum effect relationship between daratumumab dose and maximum reduction in NK cells. Similar reductions were observed in bone marrow. PBMCs from daratumumab-treated patients induced lysis by ADCC of CD38+ tumor cells in vitro, suggesting that the remaining NK cells retained cytotoxic functionality. There was no relationship between NK-cell count reduction and the efficacy or safety profile of daratumumab. Furthermore, although NK cell numbers are reduced after daratumumab treatment, they are not completely depleted and may still contribute to ADCC, clinical efficacy, and infection control.
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The analysis of normal mammary morphogenesis is facilitated by the use of mammary fat pad transplantation. The recent experiments on analysis of normal mammary epithelial stem cell activity rely heavily on this technique. In this review, we discuss the known and unknown attributes of using Matrigel in the injection of the mammary epithelial cell suspension. Matrigel greatly increases the "take" frequency of the injected cell suspension; however, there is some uncertainty regarding the interpretation of some of the results. After consideration of these issues, our conclusion is that Matrigel is important in order to obtain rigorous and reproducible results.
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Células Madre Adultas/citología , Células Madre Adultas/trasplante , Materiales Biocompatibles/administración & dosificación , Colágeno/administración & dosificación , Laminina/administración & dosificación , Glándulas Mamarias Animales/citología , Glándulas Mamarias Animales/crecimiento & desarrollo , Modelos Biológicos , Morfogénesis , Proteoglicanos/administración & dosificación , Células Madre Adultas/metabolismo , Animales , Materiales Biocompatibles/metabolismo , Diferenciación Celular , Procesos de Crecimiento Celular , Células Cultivadas , Colágeno/metabolismo , Combinación de Medicamentos , Epitelio/metabolismo , Femenino , Supervivencia de Injerto , Humanos , Laminina/metabolismo , Glándulas Mamarias Animales/metabolismo , Glándulas Mamarias Humanas/citología , Glándulas Mamarias Humanas/metabolismo , Ratones , Proteoglicanos/metabolismo , Sarcoma/metabolismo , Nicho de Células MadreRESUMEN
INTRODUCTION: T-cell lymphoma invasion and metastasis-inducing protein (Tiam1) is a Ras-related C3 botulinum toxin substrate (Rac)-specific guanine nucleotide exchange factor that was isolated based on its ability to induce a metastatic phenotype. In polarized migrating keratinocytes, Tiam1 is found at the leading edge where it cooperates with the Protease-activated receptor 1 (Par1) complex to establish front-rear polarity. Although a positive correlation has been observed between Tiam1 expression and tumor grade in a variety of human malignancies, including breast, its role in breast cancer cells has not yet been examined. METHODS: Tiam1 expression and Rac activity were examined in a panel of human breast cancer cell lines which exhibit different degrees of cell motility. The contribution of Tiam1 to cell motility was directly examined using transwell motility, and wound healing assays. RESULTS: Although we observe a striking, positive correlation between Tiam1 expression and cell motility in the panel of breast cancer cell lines, we do not observe a correlation between Tiam1 expression and overall levels of Rac activity. Consistent with this, small interfering ribonucleic acid (siRNA)-mediated suppression of Tiam1 expression limits the motility of cell lines in which Tiam1 expression is high (MDA-MB-231 and MDA-MB-453), but does not substantially alter the overall levels of activated Rac. Tiam1 overexpression is also not sufficient to increase the motility of more poorly motile cells (T-47D) or increase Rac activity. Immunofluorescence and cellular fractionations indicate that Tiam1 is found predominantly in the Golgi of breast cancer cells, and in the latter case Tiam1 was shown to co-fractionate with a limited pool of Rac1. Consistent with this Golgi localization, Tiam1 supports cell motility and Golgi reorientation in response to serum in a wound healing assay using MDA-MB-231and MDA-MB-435S cells. CONCLUSIONS: Tiam1 expression correlates with cell motility in human breast cancer cells, and is required to support the motile phenotype. Localization of endogenous Tiam1 to the Golgi, and its demonstrated role in Golgi reorientation, suggest that it may support motility through a mechanism that is discrete from its known function in leading edge dynamics.
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Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Movimiento Celular , Factores de Intercambio de Guanina Nucleótido/metabolismo , Proteínas de Unión al GTP rac/metabolismo , Línea Celular Tumoral , Femenino , Aparato de Golgi/metabolismo , Factores de Intercambio de Guanina Nucleótido/genética , Humanos , Invasividad Neoplásica , Interferencia de ARN , ARN Interferente Pequeño , Receptor PAR-1/metabolismo , Transducción de Señal , Proteína 1 de Invasión e Inducción de Metástasis del Linfoma-T , Proteína de Unión al GTP cdc42/genéticaRESUMEN
Dbs is a Rho-specific guanine nucleotide exchange factor (RhoGEF) that regulates neurotrophin-3-induced cell migration in Schwann cells. Here we report that Dbs regulates cell motility in tumor-derived, human breast epithelial cells through activation of Cdc42 and Rac1. Cdc42 and Rac1 are activated in T47D cells that stably express onco- or proto-Dbs, and activation is dependent upon growth of the cells on collagen I. Transient suppression of expression of Cdc42 or Rac1 by small interfering RNAs attenuates Dbs-enhanced motility. Both onco- and proto-Dbs-enhanced motility correlates with an increase in tyrosine phosphorylation of focal adhesion kinase on Tyr-397 and p130(Cas) on Tyr-410 and an increase in the abundance of the Crk.p130(Cas) complex. Suppression of expression of Cdc42 or its effector, Ack1, reduces tyrosine phosphorylation of focal adhesion kinase and p130(Cas) and disrupts the Crk.p130(Cas) complex. We further determined that suppression of expression of Cdc42, Ack1, p130(Cas), or Crk reduces Rac1 activation and cell motility in Dbs-expressing cells to a level comparable with that in vector cells. Therefore, a cascade of activation of Cdc42 and Rac1 by Dbs through the Cdc42 effector Ack1 and the Crk.p130(Cas) complex is established. Suppression of the expression of endogenous Dbs reduces cell motility in both T47D cells and MDA-MB-231 cells, which correlates with the down-regulation of Cdc42 activity. This suggests that Dbs activates Cdc42 in these two human breast cancer cell lines and that the normal function of Dbs may be required to support cell movement.