RESUMEN
Circulating proteomes provide a snapshot of the physiological state of a human organism responding to pathogenic challenges and drug interventions. The outcomes of patients with COVID-19 and acute respiratory distress syndrome triggered by the SARS-CoV2 virus remain uncertain. Tocilizumab is an anti-interleukin-6 treatment that exerts encouraging clinical activity by controlling the cytokine storm and improving respiratory distress in patients with COVID-19. We investigate the biological determinants of therapeutic outcomes after tocilizumab treatment. Overall, 28 patients hospitalized due to severe COVID-19 who were treated with tocilizumab intravenously were included in this study. Sera were collected before and after tocilizumab, and the patient's outcome was evaluated until day 30 post-tocilizumab infusion for favorable therapeutic response to tocilizumab and mortality. Hyperreaction monitoring measurements by liquid chromatography-mass spectrometry-based proteomic analysis with data-independent acquisition quantified 510 proteins and 7019 peptides in the serum of patients. Alterations in the serum proteome reflect COVID-19 outcomes in patients treated with tocilizumab. Our results suggested that circulating proteins associated with the most significant prognostic impact belonged to the complement system, platelet degranulation, acute-phase proteins, and the Fc-epsilon receptor signaling pathway. Among these, upregulation of the complement system by activation of the classical pathway was associated with poor response to tocilizumab, and upregulation of Fc-epsilon receptor signaling was associated with lower mortality.
Asunto(s)
Anticuerpos Monoclonales Humanizados , Tratamiento Farmacológico de COVID-19 , COVID-19 , Receptores de Interleucina-6 , SARS-CoV-2 , Humanos , Anticuerpos Monoclonales Humanizados/uso terapéutico , Masculino , Femenino , COVID-19/sangre , COVID-19/mortalidad , COVID-19/virología , Receptores de Interleucina-6/sangre , Receptores de Interleucina-6/antagonistas & inhibidores , Persona de Mediana Edad , Anciano , SARS-CoV-2/fisiología , Proteómica/métodos , Proteoma/análisis , Cromatografía Liquida/métodos , Proteínas Sanguíneas/análisis , Proteínas Sanguíneas/metabolismo , Anciano de 80 o más Años , Interleucina-6/sangreRESUMEN
BACKGROUND AND OBJECTIVES: During the worldwide pandemic of coronavirus disease 2019 (COVID-19), oncological procedures considered to be urgent could not be delayed, and a specific procedure was required to continue surgical activity. The objective was to assess the efficacy of our preoperative screening algorithm. METHODS: This observational retrospective study was performed between the 25th of March and the 12th of May 2020 in a comprehensive cancer center in France. Patients undergoing elective oncologic surgery were tested by preoperative nasopharyngeal reverse-transcription polymerase chain reaction (RT-PCR) that could be associated with a chest computerized tomography (CT) scan. RESULTS: Of the 510 screening tests (in 477 patients), only 5% (15/477) were positive for COVID-19 in 24 patients (18 RT-PCR+ and 7 CT scan+/RT-PCR-). Four patients were ultimately false positives based on the CT scan. In total, only 4.2% (20/477) of the patients were COVID-19+. The positivity rate decreased with time after the containment measures were implemented (from 7.4% to 0.8%). In the COVID-19+ group, 20% of the patients had postoperative pulmonary complications, whereas this was the case for 5% of the patients in the COVID-19 group. CONCLUSIONS: Maintaining secure surgical activity is achievable and paramount in oncology care, even during the COVID-19 pandemic, with appropriate screening based on preoperative RT-PCR.
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Prueba de Ácido Nucleico para COVID-19 , COVID-19/diagnóstico , Control de Infecciones/organización & administración , Neoplasias/cirugía , Complicaciones Posoperatorias/epidemiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Instituciones Oncológicas , Femenino , Francia , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Neoplasias/complicaciones , Neoplasias/patología , Valor Predictivo de las Pruebas , Cuidados Preoperatorios , Reproducibilidad de los Resultados , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Adulto JovenRESUMEN
PURPOSE: HPV-related oropharyngeal squamous cell carcinomas clearly represent a growing entity in the head and neck with distinct carcinogenesis, clinico-pathological presentation and survival profile. We aimed to compare the HPV prevalence rates and clinico-pathological correlations obtained with three distinct commonly used HPV detection methods. MATERIALS AND METHODS: p16-immunohistochemistry (IHC), HPV DNA viral load by real-time PCR (qPCR), and HPV genotyping by a reverse hybridization-based line probe assay (INNO-LiPA) were performed on pretreatment formalin-fixed paraffin-embedded tumor samples from 46 patients treated for single primary oropharyngeal carcinomas. RESULTS: Twenty-eight patients (61%) had a p16 overexpression in IHC. Twenty-nine patients (63%) harbored HPV DNA on qPCR. Thirty-four patients (74%) harbored HPV DNA on INNO-LiPA. The concordance analysis revealed a good agreement between both HPV DNA detection methods (κ=0.65); when both tests were positive, the depicted HPV subtypes were always concordant (HPV16 in 27 cases, HPV18 in 1 case). Agreement was moderate between IHC and qPCR (κ=0.59) and fair between IHC and INNO-LiPA (κ=0.22). CONCLUSIONS: Certain highly sensitive methods are able to detect the mere presence of HPV without any carcinogenetic involvement while other more specific tests provide proof of viral transcriptional activity and thus evidence of clinically relevant infections. The use of a stepwise approach allows reducing false positives; p16-immunostaining seems to be an excellent screening test and in situ hybridization may overcome some of the PCR limitations.
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Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/virología , Neoplasias de Cabeza y Cuello/diagnóstico , Neoplasias de Cabeza y Cuello/virología , Neoplasias Orofaríngeas/diagnóstico , Neoplasias Orofaríngeas/virología , Adulto , Anciano , Anciano de 80 o más Años , Alphapapillomavirus/aislamiento & purificación , ADN Viral/análisis , Femenino , Técnicas de Genotipaje , Papillomavirus Humano 16 , Humanos , Inmunohistoquímica , Hibridación in Situ/métodos , Masculino , Persona de Mediana Edad , Reacción en Cadena en Tiempo Real de la Polimerasa , Estudios Retrospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello , Carga ViralRESUMEN
BACKGROUND: Anti-hepatitis A virus (HAV) antibody titers at 20 IU/L are assumed to correlate with protection against HAV challenge. METHODS: We examined the accuracy and precision of currently in use immunoassays for total or anti-HAV IgG determination, by repeated testing of dilutions of the international anti-HAV standard, within a 10-50 IU/mL concentration range. RESULTS AND CONCLUSION: Eight immunoassays were evaluated. All could confidently identify people who need to be vaccinated, or who might benefit from a booster vaccine: no positive interpretation for the 10 and 15 IU/mL concentrations. However, qualitative interpretation may differ from test to test in the 15-30 IU/mL range. This variation has to be taken into account when comparing seroprevalence data.
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Virus de la Hepatitis A , Hepatitis A , Hepatitis A/diagnóstico , Anticuerpos de Hepatitis A , Humanos , Inmunoglobulina G , Estudios SeroepidemiológicosRESUMEN
BACKGROUND: Fifteen percent of patients with cancer experience symptomatic sequelae, which impair post-COVID-19 outcomes. In this study, we investigated whether a proinflammatory status is associated with the development of COVID-19 sequelae. METHODS: OnCovid recruited 2795 consecutive patients who were diagnosed with Severe Acute Respiratory Syndrome Coronavirus 2 infection between February 27, 2020, and February 14, 2021. This analysis focused on COVID-19 survivors who underwent a clinical reassessment after the exclusion of patients with hematological malignancies. We evaluated the association of inflammatory markers collected at COVID-19 diagnosis with sequelae, considering the impact of previous systemic anticancer therapy. All statistical tests were 2-sided. RESULTS: Of 1339 eligible patients, 203 experienced at least 1 sequela (15.2%). Median baseline C-reactive protein (CRP; 77.5 mg/L vs 22.2 mg/L, P < .001), lactate dehydrogenase (310 UI/L vs 274 UI/L, P = .03), and the neutrophil to lymphocyte ratio (NLR; 6.0 vs 4.3, P = .001) were statistically significantly higher among patients who experienced sequelae, whereas no association was reported for the platelet to lymphocyte ratio and the OnCovid Inflammatory Score, which includes albumin and lymphocytes. The widest area under the ROC curve (AUC) was reported for baseline CRP (AUC = 0.66, 95% confidence interval [CI]: 0.63 to 0.69), followed by the NLR (AUC = 0.58, 95% CI: 0.55 to 0.61) and lactate dehydrogenase (AUC = 0.57, 95% CI: 0.52 to 0.61). Using a fixed categorical multivariable analysis, high CRP (odds ratio [OR] = 2.56, 95% CI: 1.67 to 3.91) and NLR (OR = 1.45, 95% CI: 1.01 to 2.10) were confirmed to be statistically significantly associated with an increased risk of sequelae. Exposure to chemotherapy was associated with a decreased risk of sequelae (OR = 0.57, 95% CI: 0.36 to 0.91), whereas no associations with immune checkpoint inhibitors, endocrine therapy, and other types of systemic anticancer therapy were found. CONCLUSIONS: Although the association between inflammatory status, recent chemotherapy and sequelae warrants further investigation, our findings suggest that a deranged proinflammatory reaction at COVID-19 diagnosis may predict for sequelae development.
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COVID-19 , Proteína C-Reactiva/análisis , COVID-19/complicaciones , COVID-19/epidemiología , Prueba de COVID-19 , Progresión de la Enfermedad , Humanos , Lactato Deshidrogenasas , Linfocitos/química , Neutrófilos/química , Pronóstico , Curva ROC , Sistema de Registros , Estudios RetrospectivosRESUMEN
Haematopoietic stem cell transplantation (HSCT) recipients are at risk for severe respiratory syncytial virus (RSV) infection. Two prognostic scores have been proposed to predict the risk of progression from upper respiratory tract infection (URTI) to lower respiratory tract infection (LRTI) and death. This was a multicentre study of allogeneic HSCT recipients diagnosed with an RSV infection between 2010 and 2019 who were retrospectively stratified by the immunodeficiency scoring index (ISI) and the severe immunodeficiency (SID) score. Endpoints were overall survival, RSV-attributable mortality and progression to LRTI after URTI. Prognostic analyses were performed using Cox regression models. We included 147 consecutive patients, including 94 (63.9%) initially diagnosed with URTI and 53 (36.1%) with LRTI. At 90 days, 14 patients had died (survival rate, 90.5%; 95% CI: 85.9-95.3), and nine deaths were attributable to RSV (attributable mortality rate, 5.4%; 95% CI: 2.5-10.0). The cumulative 90-day incidence of LRTI after URTI was 13.8% (95% CI: 7.8-21.6). Neither score showed prognostic value for mortality, while the ISI allowed the prediction of progression to LRTI (p = 0.0008). Our results do not fully replicate the results previously reported in cohorts of HSCT recipients. This may reflect the recent epidemiology of RSV infections in this HSCT cohort.
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Trasplante de Células Madre Hematopoyéticas , Infecciones por Virus Sincitial Respiratorio , Infecciones del Sistema Respiratorio , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Trasplante de Células Madre Hematopoyéticas/métodos , Humanos , Pronóstico , Infecciones por Virus Sincitial Respiratorio/diagnóstico , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
PURPOSE: Patients with cancer are presumed to be more vulnerable to COVID-19. We evaluated a screening strategy combining chest computed tomography (CT) and reverse-transcription polymerase chain reaction (RT-PCR) for patients treated with radiation therapy at our cancer center located in a COVID-19 French hotspot during the first wave of the pandemic. METHODS AND MATERIALS: Chest CT images were proposed during radiation therapy CT simulation. Images were reviewed by an expert radiologist according to the COVID-19 Reporting and Data System classification. Nasal swabs with RT-PCR assay were initially proposed in cases of suspicious imaging or clinical context and were eventually integrated into the systematic screening. A dedicated radiation therapy workflow was proposed for COVID-19 patients to limit the risk of contamination. RESULTS: From March 18, 2020 to May 1, 2020, 480 patients were screened by chest CT, and 313 patients had both chest CT and RT-PCR (65%). The cumulative incidence of COVID-19 was 5.4% (95% confidence interval [CI], 3.6-7.8; 26 of 480 patients). Diagnosis of COVID-19 was made before radiation therapy for 22 patients (84.6%) and during RT for 4 patients (15.3%). Chest CT directly aided the diagnosis of 7 cases in which the initial RT-PCR was negative or not feasible, out of a total of 480 patients (1.5%) and 517 chest CT acquisitions. Four patients with COVID-19 at the time of the chest CT screening had a false negative CT. Sensitivity and specificity of chest CT screening in patients with both RT-PCR and chest CT testing were estimated at 0.82 (95% CI, 0.60-0.95) and 0.98 (95% CI, 0.96-0.99), respectively. Adaptation of the radiation therapy treatment was made for all patients, with 7 postponed treatments (median: 5 days; interquartile range, 1.5-14.8). CONCLUSIONS: The benefit of systematic use of chest CT screening during CT simulation for patients undergoing radiation therapy during the COVID-19 pandemic seemed limited.
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Prueba de Ácido Nucleico para COVID-19 , COVID-19/diagnóstico , Tomografía Computarizada Multidetector , Neoplasias/radioterapia , Adolescente , Adulto , Anciano , COVID-19/complicaciones , COVID-19/diagnóstico por imagen , COVID-19/epidemiología , Instituciones Oncológicas , Niño , Intervalos de Confianza , Femenino , Francia/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Neoplasias/complicaciones , Radiografía Torácica/métodos , Estudios Retrospectivos , Sensibilidad y Especificidad , Tomografía Computarizada Espiral , Adulto JovenRESUMEN
The SARS-COV-2 pandemic has put pressure on intensive care units, so that identifying predictors of disease severity is a priority. We collect 58 clinical and biological variables, and chest CT scan data, from 1003 coronavirus-infected patients from two French hospitals. We train a deep learning model based on CT scans to predict severity. We then construct the multimodal AI-severity score that includes 5 clinical and biological variables (age, sex, oxygenation, urea, platelet) in addition to the deep learning model. We show that neural network analysis of CT-scans brings unique prognosis information, although it is correlated with other markers of severity (oxygenation, LDH, and CRP) explaining the measurable but limited 0.03 increase of AUC obtained when adding CT-scan information to clinical variables. Here, we show that when comparing AI-severity with 11 existing severity scores, we find significantly improved prognosis performance; AI-severity can therefore rapidly become a reference scoring approach.
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COVID-19/diagnóstico , COVID-19/fisiopatología , Aprendizaje Profundo , Redes Neurales de la Computación , Tomografía Computarizada por Rayos X/métodos , Inteligencia Artificial , COVID-19/clasificación , Humanos , Modelos Biológicos , Análisis Multivariante , Pronóstico , Radiólogos , Índice de Severidad de la EnfermedadRESUMEN
Coronavirus disease 2019 (COVID-19) and its causative virus, SARS-CoV-2, pose considerable challenges for the management of oncology patients. COVID-19 presents as a particularly severe respiratory and systemic infection in aging and immunosuppressed individuals, including patients with cancer. Moreover, severe COVID-19 is linked to an inflammatory burst and lymphopenia, which may aggravate cancer prognosis. Here we discuss why those with cancer are at higher risk of severe COVID-19, describe immune responses that confer protective or adverse reactions to this disease and indicate which antineoplastic therapies may either increase COVID-19 vulnerability or have a dual therapeutic effect on cancer and COVID-19.
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COVID-19/inmunología , Humanos , SARS-CoV-2RESUMEN
Circulating endothelial cells (CEC) are currently proposed as a potential biomarker for measuring the impact of anti-angiogenic treatments in cancer. However, the lack of consensus on the appropriate method of CEC measurement has led to conflicting data in cancer patients. A validated assay adapted for evaluating the clinical utility of CEC in large cohorts of patients undergoing anti-angiogenic treatments is needed. We developed a four-color flow cytometric assay to measure CEC as CD31(+), CD146(+), CD45(-), 7-amino-actinomycin-D (7AAD)(-) events in whole blood. The distinctive features of the assay are: (1) staining of 1 ml whole blood, (2) use of a whole blood IgPE control to measure accurately background noise, (3) accumulation of a large number of events (almost 5 10(6)) to ensure statistical analysis, and (4) use of 10 microm fluorescent microbeads to evaluate the event size. Assay reproducibility was determined in duplicate aliquots of samples drawn from 20 metastatic cancer patients. Assay linearity was tested by spiking whole blood with low numbers of HUVEC. Five-color flow cytometric experiments with CD144 were performed to confirm the endothelial origin of the cells. CEC were measured in 20 healthy individuals and 125 patients with metastatic cancer. Reproducibility was good between duplicate aliquots (r(2)=0.948, mean difference between duplicates of 0.86 CEC/ml). Detected HUVEC correlated with spiked HUVEC (r(2)=0.916, mean recovery of 100.3%). Co-staining of CD31, CD146 and CD144 confirmed the endothelial nature of cells identified as CEC. Median CEC levels were 6.5/ml (range, 0-15) in healthy individuals and 15.0/ml (range, 0-179) in patients with metastatic carcinoma (p<0.001). The assay proposed here allows reproducible and sensitive measurement of CEC by flow cytometry and could help evaluate CEC as biomarkers of anti-angiogenic therapies in large cohorts of patients.
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Inhibidores de la Angiogénesis/uso terapéutico , Recuento de Células Sanguíneas/métodos , Células Endoteliales/citología , Citometría de Flujo/métodos , Antígenos CD/análisis , Biomarcadores , Cadherinas/análisis , Humanos , Metástasis de la Neoplasia , Neoplasias/sangre , Reproducibilidad de los Resultados , Coloración y EtiquetadoRESUMEN
This corrects the article DOI: 10.1038/srep27059.
RESUMEN
The pig is an emerging animal model, complementary to rodents for basic research and for biomedical and agronomical purposes. However despite the progress made on mouse and rat models to produce genuine pluripotent cells, it remains impossible to produce porcine pluripotent cell lines with germline transmission. Reprogramming of pig somatic cells using conventional integrative strategies remains also unsatisfactory. In the present study, we compared the outcome of both integrative and non-integrative reprogramming strategies on pluripotency and chromosome stability during pig somatic cell reprogramming. The porcine cell lines produced with integrative strategies express several pluripotency genes but they do not silence the integrated exogenes and present a high genomic instability upon passaging. In contrast, pig induced pluripotent-like stem cells produced with non-integrative reprogramming system (NI-iPSLCs) exhibit a normal karyotype after more than 12 months in culture and reactivate endogenous pluripotency markers. Despite the persistent expression of exogenous OCT4 and MYC, these cells can differentiate into derivatives expressing markers of the three embryonic germ layers and we propose that these NI-iPSLCs can be used as a model to bring new insights into the molecular factors controlling and maintaining pluripotency in the pig and other non-rodent mammalians.
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Reprogramación Celular , Inestabilidad Cromosómica , Cromosomas de los Mamíferos/química , Fibroblastos/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Animales , Biomarcadores/metabolismo , Ciclo Celular/genética , Diferenciación Celular , Línea Celular , Fibroblastos/citología , Expresión Génica , Perfilación de la Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Células Madre Pluripotentes Inducidas/citología , Cariotipificación , Lentivirus/genética , Lentivirus/metabolismo , Factor 3 de Transcripción de Unión a Octámeros/genética , Factor 3 de Transcripción de Unión a Octámeros/metabolismo , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , PorcinosRESUMEN
We previously demonstrated, using the glioblastoma cell line U87MG as an experimental model, that the adenoviral mediated overexpression of the truncated protein HARPΔ111-136 inhibits the proliferation of these cells in vitro as well as tumor growth and angiogenesis in vivo. This study focused on identifying the underlying mechanisms for the observed antitumoral effect. The present study demonstrated that HARPΔ111-136 induced the ATF4/ATF3/CHOP cascade resulting in a strong expression of the proapoptotic protein CHOP, leading to tumor cell apoptosis as demonstrated by PARP cleavage and FACS analysis. siRNA-mediated CHOP gene silencing abolished Ad-HARPΔ111-136 induced apoptosis. Moreover, Ad-HARPΔ111-136 increased the expression of the death receptor DR5 and enhanced U87MG cells sensitivity in vitro to TRAIL a DR5 ligand with subsequent activation of caspase 8. Infection of U87MG cells with Ad-HARPΔ111-136 also enhanced radiation-induced apoptosis. In vivo, the combination of Ad-HARPΔ111-136 and radiation therapy resulted in a striking inhibition (92%) of the growth of U87MG xenografts, resulting from the potent effect on tumor angiogenesis and tumor cell apoptosis as determined by TUNEL analysis. Taken together, our results indicated that the inhibitor HARPΔ111-136 sensitized U87MG cells to apoptosis.
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Apoptosis/efectos de la radiación , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/radioterapia , ADN Helicasas/biosíntesis , Glioblastoma/patología , Glioblastoma/radioterapia , Fragmentos de Péptidos/biosíntesis , Animales , Apoptosis/fisiología , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Adhesión Celular , Línea Celular Tumoral , Proliferación Celular , ADN Helicasas/genética , Femenino , Glioblastoma/genética , Glioblastoma/metabolismo , Humanos , Inmunohistoquímica , Ratones , Ratones Desnudos , Fragmentos de Péptidos/genética , Factor de Transcripción CHOP , Transfección , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Angiogenesis is essential for tumor growth and metastatic dissemination. We have previously shown that human angiotensinogen (AGT) can in vitro inhibit endothelial cell proliferation and migration, capillary-like tube formation, and neovascularization. To determine whether AGT can exert an antitumoral effect through its antiangiogenic properties, we constructed a recombinant adenovirus carrying the human angiotensinogen gene under the control of the cytomegalovirus promoter (AdAGT). In vitro studies showed that AdAGT selectively inhibited endothelial cell proliferation. In vivo, injections of AdAGT into preestablished human MDA-MB-231 mammary carcinomas in nude mice inhibited tumor growth by 70% compared to controls, with 21% total regression. This effect was associated with the suppression of intratumoral vascularization and marked necrosis. Furthermore, in vitroAdAGT infection of MDA-MB-231 and murine melanoma B16F10 cells strongly blocked their in vivo tumorigenicity. Then, in mice expressing high levels of AGT (i.e., either iv injected with AdAGT or HuAGT transgenic mice), the number of B16F10 pulmonary metastases was 85% lower than in control C57BL/6 mice. Our data demonstrate that AGT is a very potent antiangiogenic factor in vivo, independent of angiotensin II generation. Its delivery by gene transfer represents a promising new strategy to block primary tumor growth and to prevent metastasis.
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Adenoviridae/genética , Angiotensinógeno/genética , Terapia Genética/métodos , Metástasis de la Neoplasia/terapia , Neoplasias Experimentales/terapia , Neovascularización Patológica/terapia , Animales , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Células Endoteliales/citología , Endotelio Vascular/citología , Técnicas de Transferencia de Gen , Células HeLa , Humanos , Melanoma Experimental/irrigación sanguínea , Melanoma Experimental/secundario , Melanoma Experimental/terapia , Ratones , Ratones Endogámicos C57BL , Ratones Desnudos , Trasplante de Neoplasias , Neoplasias Experimentales/irrigación sanguínea , Neoplasias Experimentales/patología , Trasplante HeterólogoRESUMEN
We describe an approach employing intramuscular plasmid electrotransfer to deliver secretable forms of K1-5 and K1-3-HSA (a fusion of K1-3 with human serum albumin), which span, respectively, five and three of the five kringle domains of plasminogen. A tetracycline-inducible system (Tet-On) composed of three plasmids coding, respectively, for the transgene, the tetracycline transcriptional activator rtTA, and the silencer tTS was employed. K1-3-HSA and K1-5, produced from C2C12 muscle cells, were found to inhibit endothelial cell (HMEC-1) proliferation by 30 and 51%, respectively. In vivo, the expression of the transgene upon doxycycline stimulation was rapid, stable, and tightly regulated (no background expression) and could be maintained for at least 3 months. Blood half-lives of 2.1 and 3.7 days were found for K1-5 and K1-3-HSA, respectively. The K1-5 protein was secreted from muscle into blood at a level of 45 ng/ml, which was sufficient to inhibit MDA-MB-231 tumor growth by 81% in nude mice and B16-F10 melanoma cell lung invasion in C57BL/6 mice by 73%. PECAM-1 immunostaining studies revealed modest tumor vasculature in mice expressing K1-5. In contrast, K1-3-HSA, although secreted into blood at much higher level (250 ng/ml) than K1-5, had no effect on tumor growth.