RESUMO
Primary dose reduction (PDR) in the first course of chemotherapy is an empirical practice, commonly used in older population. Patients over 70 years old receiving a first course of chemotherapy for a solid tumor were enrolled. A total of 179 patients were included. Standard dose was used in 69.8% of patients, while 30.2% received PDR of chemotherapy. Only 29.6% received a standardized geriatric assessment. Patients receiving standard doses presented 83.2% of toxicities, while 68% of toxicities were reported in patients receiving PDR. The toxicity rate was significantly decreased in patients treated with reduced first-cycle dose of chemotherapy.
Assuntos
Neoplasias , Humanos , Idoso , Neoplasias/tratamento farmacológico , Masculino , Feminino , Estudos Retrospectivos , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Antineoplásicos/efeitos adversos , Antineoplásicos/administração & dosagem , Antineoplásicos/uso terapêutico , Avaliação Geriátrica , Relação Dose-Resposta a DrogaRESUMO
Multidisciplinary team meeting (MDT) became a standard of care in cancer management. The COVID-19 epidemic induced unprecedented pressure on the health system. The impact of this health crisis on MDTs held within a regional French health structures was analyzed. A decrease in the total number of records discussed in hematological, digestive, thoracic, gynecological and genitourinary MDTs was observed following the 1st wave of the COVID-19 pandemic. This decrease was generally maintained during the 2nd and 3rd wave. MDTs activity back in order from the 4th wave. The COVID-19 pandemic has challenged MDTs settings. The implementation of virtual technologies offers an opportunity to improve MDTs organization.
Assuntos
COVID-19 , Neoplasias , Humanos , Pandemias , Equipe de Assistência ao Paciente , COVID-19/epidemiologia , Neoplasias/epidemiologia , Neoplasias/terapia , Surtos de DoençasRESUMO
Osteopontin (OPN) and Bone Sialoprotein (BSP), abundantly expressed by osteoblasts and osteoclasts, appear to have important, partly overlapping functions in bone. In gene-knockout (KO, -/-) models of either protein and their double (D)KO in the same CD1/129sv genetic background, we analyzed the morphology, matrix characteristics, and biomechanical properties of femur bone in 2 and 4 month old, male and female mice. OPN-/- mice display inconsistent, perhaps localized hypermineralization, while the BSP-/- are hypomineralized throughout ages and sexes, and the low mineralization of young DKO mice recovers with age. The higher contribution of primary bone remnants in OPN-/- shafts suggests a slow turnover, while their lower percentage in BSP-/- indicates rapid remodeling, despite FTIR-based evidence in this genotype of a high maturity of the mineralized matrix. In 3-point bending assays, OPN-/- bones consistently display higher Maximal Load, Work to Max. Load and in young mice Ultimate Stress, an intrinsic characteristic of the matrix. Young male and old female BSP-/- also display high Work to Max. Load along with low Ultimate Stress. Principal Component Analysis confirms the major role of morphological traits in mechanical competence, and evidences a grouping of the WT phenotype with the OPN-/- and of BSP-/- with DKO, driven by both structural and matrix parameters, suggesting that the presence or absence of BSP has the most profound effects on skeletal properties. Single or double gene KO of OPN and BSP thus have multiple distinct effects on skeletal phenotypes, confirming their importance in bone biology and their interplay in its regulation.
Assuntos
Sialoproteína de Ligação à Integrina , Osteopontina , Animais , Feminino , Masculino , Camundongos , Fenômenos Biomecânicos , Osso e Ossos/metabolismo , Densidade Óssea/fisiologia , Densidade Óssea/genética , Calcificação Fisiológica/fisiologia , Calcificação Fisiológica/genética , Fêmur/metabolismo , Sialoproteína de Ligação à Integrina/genética , Sialoproteína de Ligação à Integrina/metabolismo , Camundongos Knockout , Osteopontina/genética , Osteopontina/metabolismoRESUMO
Radiation therapy plays a fundamental role in oncological emergencies such as superior vena cava syndrome (SVCS) and metastatic epidural spinal cord compression (MESCC). These are two examples of critical complications of metastatic cancer in terms of pain and functional impact (respiratory and/or neurological). The aim of this review is to explore the current indications, treatment options and outcomes for emergency radiotherapy regarding to these complications.Regarding SVCS, studies are mostly retrospective and unanimously demonstrated a beneficial effect of radiotherapy on symptom relief. Spinal cord compression remains an indication for urgent radiotherapy, and should be combined with surgery when possible. The innovative stereotactic body radiotherapy (SBRT) showed promising results, however this technique requires small volumes and more time preparation and therefore is often unsuitable for SVCS and MESCC emergencies.This review concluded that radiotherapy has a central role to play within a multimodal approach for SVCS and MESCC treatment. Further prospective studies are needed to confirm the effectiveness of radiation and establish the criteria for selecting patients to benefit from this treatment option.
Assuntos
Neoplasias , Compressão da Medula Espinal , Neoplasias da Coluna Vertebral , Síndrome da Veia Cava Superior , Humanos , Compressão da Medula Espinal/etiologia , Compressão da Medula Espinal/radioterapia , Estudos Retrospectivos , Síndrome da Veia Cava Superior/etiologia , Síndrome da Veia Cava Superior/radioterapia , Emergências , Neoplasias/complicações , Neoplasias/radioterapia , Neoplasias da Coluna Vertebral/radioterapia , Neoplasias da Coluna Vertebral/secundárioRESUMO
Over the years, radiotherapy has seen continual improvements and has become a standard treatment for most malignant tumors. Cardiotoxicity is a well-known radiotherapy side effect, leading to the risk of long-term morbidity and mortality in cancer survivors. Therefore, minimizing radiotherapy-related cardiotoxicity remains an important challenge in cancer care management. Indeed, multiple dose constraints were proposed for the heart and its substructures. In addition, sparing techniques were developed to reduce the exposure of the heart to ionizing radiation and are currently used in daily clinical routine. The purpose of this review is to summarize the current knowledge about radiation-induced cardiotoxicity, to discuss the previously cardiac dose constraints, and to evaluate the various management strategies.
Assuntos
Cardiotoxicidade , Neoplasias , Humanos , Cardiotoxicidade/etiologia , Neoplasias/radioterapia , Lesões por Radiação/etiologia , Radioterapia/efeitos adversos , Radioterapia/métodos , Radioterapia (Especialidade)/métodos , Coração/efeitos da radiação , Coração/efeitos dos fármacosRESUMO
Scarce data investigate the impact of radiotherapy (RT) on biology markers. An analysis of ancillary study of RIT (Radiation Impact on Thromboembolic events) prospective trial was carried out. All patients with non-metastatic solid tumors and treated with radiotherapy and/or brachytherapy in curative and consenting to have blood samples were included. A significant decrease in white blood count, (i.e. lymphocytes, monocytes, neutrophils and basophils) and platelet counts was observed after RT and maintained at 6 months. Whereas, eosinophils, D-dimers and hemoglobin levels were affected respectively 3 months and 6 months after RT initiation. Conversely, red cells count and CRP level were not affected by RT. This study is an advocacy to develop an understanding of basic immune system in relation with RT.
Assuntos
Braquiterapia , Neoplasias , Humanos , Estudos Prospectivos , Neoplasias/radioterapia , Neoplasias/patologia , Neutrófilos , LinfócitosRESUMO
INTRODUCTION: Integrating telemedicine into cancer care remains a major challenge. There are little clinical evidence for teleconsultation efficacy and safety in daily oncology practice. This study as a pioneering experience, aimed to analyze patient and physician opinions regarding the implementation of telemedicine consultations, and to identify major limitations of telehealth spread in an oncology institute. MATERIAL AND METHODS: During COVID-19 lockdown, patients and physicians who took part to at least one video-based teleconsultation between March and May 2020, were enrolled in this observational study. All eligible patients received an anonymous online questionnaire. On the other hand, all physicians eligible to participate were asked through email to complete a questionnaire. RESULTS: In this study, 31 physicians and 304 patients consented to participate in this study by answering the questionnaire and were included. Regarding telemedicine satisfaction, 65.8% of patients were satisfied. The lack of clinical examination was the major limitation reported by 77% of patients. Patients belonging to a high socio-professional category were statistically more dissatisfied with the relationship with their doctor (OR = 2.31 and 95% CI [1.12; 4.74]). CONCLUSION: This study showed promising results of incorporating video-based teleconsultations into cancer patient management. Randomized clinical trials are needed in order to accelerate the digital implementation in clinical practice.
Assuntos
COVID-19 , Neoplasias , Médicos , Telemedicina , Humanos , Telemedicina/métodos , Encaminhamento e Consulta , COVID-19/epidemiologia , Satisfação Pessoal , Neoplasias/terapiaRESUMO
PURPOSE OF REVIEW: This study aims to gather the current state of the literature about anti-Nectin-4 innovative associations in solid tumors and to investigate underlying resistance mechanisms. RECENT FINDINGS: Antibody-drug conjugate (ADC) targeting Nectin-4 efficacy gained attention and offers a promising association with other antineoplastic drugs especially in urothelial carcinoma. The heterogeneity of Nectin-4 expression across the molecular subtypes was highlighted especially in urothelial cancers. A unique study using preclinical models demonstrated an upregulation of P-gp expression, which may explain the anti-Nectin-4 resistance mechanisms. Further studies are urgently needed to understand anti-Nectin-4 sensitivity and resistance phenomenon. The growing therapeutic associations of enfortumab vedotin offer optimistic opportunities in management and treatment of wide range of solid tumors including rare aggressive malignancies.
Assuntos
Antineoplásicos , Carcinoma de Células de Transição , Imunoconjugados , Neoplasias da Bexiga Urinária , Humanos , Neoplasias da Bexiga Urinária/patologia , Carcinoma de Células de Transição/tratamento farmacológico , Moléculas de Adesão Celular/metabolismo , Moléculas de Adesão Celular/uso terapêutico , Antineoplásicos/uso terapêutico , Imunoconjugados/uso terapêuticoRESUMO
PURPOSE OF REVIEW: This study aims to gather the current state of the literature about therapeutic approaches and management of oligometastatic renal cell carcinoma. RECENT FINDINGS: Two recent stereotactic body radiotherapy (SBRT) studies gained attention and offered a promising outcome alone or in association with antineoplastic drugs especially in oligometastatic renal cell carcinoma. If one can consider evidence-based medicine as the sole therapeutic option, many unresolved questions are still pending. Thus, therapeutic approaches in oligometastatic renal cell carcinoma are still working. Further phase III clinical trials are urgently needed to validate the last 2 phase II involving SBRT and improve knowledge for defining the right care to the right patient at the right time. In addition, a discussion in a disciplinary consultation meeting remains essential to validate the arrangement between systemic treatments and focal treatments that will best benefit the patient.
Assuntos
Carcinoma de Células Renais , Neoplasias Renais , Radiocirurgia , Humanos , Carcinoma de Células Renais/terapia , Neoplasias Renais/terapiaRESUMO
Little data are available regarding the effects of COVID-19 vaccine in cancer patients undergoing immunotherapy. Thereby, COVID-19 vaccine-related adverse events were monitored through a short questionnaire in solid cancer patients receiving immunotherapy. A total of 95 patients were included in this study. Two doses of vaccines were administered to cancer patients which mainly received Pembrolizumab (51.1%). Respectively 78.2% and 62.2% of patients reported no adverse events after the first and the second dose regardless of the type of vaccine used. Considering the high mortality rate due to COVID-19 among cancer patients, this study demonstrated the good tolerance of COVID-19 vaccine.
Assuntos
Vacinas contra COVID-19 , COVID-19 , Neoplasias , COVID-19/prevenção & controle , Vacinas contra COVID-19/efeitos adversos , Humanos , Imunoterapia , Neoplasias/tratamento farmacológicoRESUMO
Aging is a universal complex and multifactorial physiological process that leads to the increasing incidence of various diseases including cancer. Indeed, 40% of individuals aged 65 years and over will have newly diagnosed cancers. Although most treated patients are elderly people, a low inclusion of the geriatric population is observed in most clinical trials. Furthermore, lethal side effects of antineoplastic therapy are markedly exacerbated with aging. Most cancer therapies were validated on young mice models, complicating results transposition to elderly patients. Thus, understanding the role of aging in tumor progression and response to cancer therapies with accurate preclinical models must be investigated. Therefore, this review aimed to summarize the state of the literature about preclinical models used to investigate the impact of aging microenvironment on tumorigenic potential, and on antineoplastic therapy response. Despite the advances in technology, and the increasing incidence of cancer in the elderly population, this present review focuses on the few studies using preclinical tumor model of aging. Since the biology of aging is challenging, aging animal models are an inevitable prelude. New emerging tools such as human organoid offer a promising path in research dedicated to aging.
Assuntos
Antineoplásicos , Neoplasias , Idoso , Envelhecimento , Animais , Humanos , Camundongos , Microambiente TumoralRESUMO
Coronavirus disease outbreak has affected all aspect of clinical care including cancer clinical trials. To minimize exposure of frail cancer patients, an implementation of telemedicine was retained. The impact of this implementation on primary and secondary endpoints criteria of ongoing clinical trials was analyzed. Out of 128 oncology clinical trials, 25 (19%) had an implementation of teleconsultation. Poor data reporting induced mainly a bias on qualitative and descriptive primary endpoints than those assessing efficacy (80% vs 20%; p < 0.001). The integration of telemedicine and E-technologies in the medical practices and clinical trials must be designed and validated.
Assuntos
COVID-19/prevenção & controle , Ensaios Clínicos como Assunto/métodos , Oncologia/métodos , Neoplasias/terapia , SARS-CoV-2/isolamento & purificação , Telemedicina/métodos , COVID-19/epidemiologia , COVID-19/virologia , Ensaios Clínicos como Assunto/normas , Ensaios Clínicos como Assunto/estatística & dados numéricos , Surtos de Doenças , Humanos , Oncologia/normas , Oncologia/estatística & dados numéricos , Neoplasias/classificação , Neoplasias/diagnóstico , Avaliação de Resultados em Cuidados de Saúde/métodos , Avaliação de Resultados em Cuidados de Saúde/normas , Avaliação de Resultados em Cuidados de Saúde/estatística & dados numéricos , Relatório de Pesquisa/normas , SARS-CoV-2/fisiologia , Telemedicina/normas , Telemedicina/estatística & dados numéricosRESUMO
PURPOSE: The use of oral cancer drugs (OAD) has increased over the last two decades. The objective of this study was to measure the impact of a nurse-led telephone follow-up in the therapeutic management of patients treated with an OAD regarding toxicity, medication adherence and quality of life. METHODS: A randomized, multicenter, controlled trial was conducted. All consecutive over 18-year-old patients, treated in medical oncology, radiotherapy, or hematology departments, receiving OAD for any cancer were invited to participate to the study. A total of 183 patients treated for solid or hematological cancers with an OAD were randomly assigned to receive a nurse-led telephone follow-up or standard care for 24 weeks. Data were collected between 2015 and 2018. RESULTS: Nurse telephone follow-up did not improve the global score toxicity in the intervention group. However, telephone calls directed by trained nurses induced a significant decrease in number of patients with grade 3 adverse events throughout the follow-up [OR 0.45 (IC à 95%) (0.23, 0.9)](P = 0.03). There was no significant difference in quality of life and medication adherence between groups at any follow-up time point. CONCLUSIONS: In this first French real-life study, the advice provided by qualified nurses via phone calls improved the management of grade 3 toxicities but failed to demonstrate an improvement of all grades of toxicities. More prospective studies are needed to confirm the impact of telephone calls on the toxicities related to OAD. TRIAL REGISTRATION: Clinical trial registration is NCT02459483. Protection committee SUD-ESTI registration is 2015-A00527-42 on 13 April 2015. National Agency for the Safety of Medicines and Health Products registration is 150619-B on the 27 may 2015.
Assuntos
Antineoplásicos/uso terapêutico , Adesão à Medicação/psicologia , Qualidade de Vida/psicologia , Idoso , Antineoplásicos/farmacologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
Hypoxia involves neoplastic cells. Unlike normal tissue, solid tumors are composed of aberrant vasculature, leading to a hypoxic microenvironment. Hypoxia is also known to be involved in both metastasis initiation and therapy resistance. Radiotherapy is the appropriate treatment in about half of all cancers, but loco-regional control failure and a disease recurrence often occur due to clinical radioresistance. Hypoxia induces radioresistance through a number of molecular pathways, and numerous strategies have been developed to overcome this. Nevertheless, these strategies have resulted in disappointing results, including adverse effects and limited efficacy. Additional clinical studies are needed to achieve a better understanding of the complex hypoxia pathways. This review presents an update on the mechanisms of hypoxia in radioresistance in solid tumors and the potential therapeutic solutions.
Assuntos
Hipóxia/complicações , Hipóxia/fisiopatologia , Neoplasias/complicações , Neoplasias/radioterapia , Tolerância a Radiação , Feminino , Humanos , MasculinoRESUMO
PURPOSE: Despite the decreasing of environmental contamination throughout the anticancer drug circuit, the administration of chemotherapies remains at risk of occupational exposure for nurses. Many medical devices aim at securing administration, but none have been scientifically evaluated to verify the actual improvement. METHODS: A monocentric comparative before/after study was carried out in an oncology day hospital to evaluate the efficacy of Safe Infusion Devices in reducing drug exposure compared to usual infusion practices. The rate of nurses' gloves contamination was estimated. To avoid false negatives and to ensure sampling reproducibility, each sample of gloves was contaminated with a drop of topotecan. Association between contamination and other variables was investigated using a multivariate logistic regression analysis. RESULTS: The usual practice led to a rate of 58.3% of contaminated samples while Safe Infusion Devices to a rate of 15%: Safe Infusion Devices reduced the risk of gloves contamination by 85% in multivariate analysis (Odds ratio = 0.15; 95% confidence interval = 0.05-0.46; p < 0.001). Topotecan was identified in 100% of the samples. Only one case of cross-contamination has occurred. CONCLUSION: Despite the current practice of using neutral solvent-purged infusers, the occupational exposure remains high for nurses and Safe Infusion Devices significantly reduced this risk of exposure. However, glove contamination is only a surrogate endpoint. The results confirmed that the disconnection of empty bags resulted in occupational exposure. Except a contamination due to the leakage of a bag, no cross-contamination was detected. Safe Infusion Devices were highly effective but did not completely eliminate exposure.
Assuntos
Antineoplásicos/análise , Infusões Intravenosas/instrumentação , Enfermeiras e Enfermeiros , Exposição Ocupacional/prevenção & controle , Ciclofosfamida/análise , Luvas Protetoras , Humanos , Irinotecano/análise , Pemetrexede/análise , Topotecan/análiseRESUMO
BACKGROUND: Oral mucositis (OM) is a severe complication cancer patients undergo when treated with chemoradiotherapy. Photobiomodulation (PBM) therapy also known as low-level laser therapy has been increasingly used for the treatment of such oral toxicity. The aim of this review is to discuss the mechanisms of photobiomodulation (PBM) regarding OM prevention and treatment, and more precisely to focus on the effect of PBM on tumor and healthy cells. METHODS: MEDLINE/PubMed, and google scholar were searched electronically. Selected studies were focusing on PBM effects on tumor and healthy cells. RESULTS: PBM interactions with the tissue and additional mechanism in OM therapy were detailed in this review. Moreover, this review highlighted a controversy about the carcinogenic effect of PBM. Indeed, Many studies reported that PBM could enhance malignant cell proliferation; suggesting that PBM would have no protective effect. In addition to acting on cancer cells, PBM may damage healthy cells. CONCLUSION: More prospective studies are needed to assess the effect of PBM on cancer cells in order to improve its use for OM prevention and treatment.
Assuntos
Terapia com Luz de Baixa Intensidade , Neoplasias , Estomatite , Quimiorradioterapia , Humanos , Estudos Prospectivos , Estomatite/etiologia , Estomatite/prevenção & controleRESUMO
Leptomeningeal metastasis (LM) in solid tumors are rare, even more in renal cell carcinoma (RCC). To date there is a lack of consensual treatment modalities of leptomeningeal metastasis. Furthermore, with the improvement of outcomes and more effective systemic targeted therapies, the management of leptomeningeal metastasis becomes a real challenge. We here report two cases of RCC with leptomeningeal metastasis at initial diagnosis. Both patients had concurrent adjacent skull bone metastasis. Therapeutic management of both patients consisted in surgical resection, followed by radiotherapy in one case. Systemic treatment was delayed according to current recommendations for the management of metastatic RCC. The aim of this work is to report the therapeutic approach and related outcomes and also provide a review of the currently available literature on leptomeningeal disease in renal cell carcinoma. Indeed, local treatment with curative outcome of meningeal location in RCC should be performed specially in LM at initial diagnosis.
Assuntos
Carcinoma de Células Renais/diagnóstico por imagem , Neoplasias Renais/diagnóstico por imagem , Neoplasias Meníngeas/secundário , Neoplasias Cranianas/secundário , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/radioterapia , Terapia Combinada , Humanos , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/radioterapia , Masculino , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/radioterapia , Neoplasias Meníngeas/cirurgia , Pessoa de Meia-Idade , Neoplasias Cranianas/radioterapia , Neoplasias Cranianas/cirurgia , Sunitinibe/uso terapêutico , Resultado do TratamentoRESUMO
The bone organ integrates the activity of bone tissue, bone marrow, and blood vessels and the factors ensuring this coordination remain ill defined. Bone sialoprotein (BSP) is with osteopontin (OPN) a member of the small integrin binding ligand N-linked glycoprotein (SIBLING) family, involved in bone formation, hematopoiesis and angiogenesis. In rodents, bone marrow ablation induces a rapid formation of medullary bone which peaks by â¼8 days (d8) and is blunted in BSP-/- mice. We investigated the coordinate hematopoietic and vascular recolonization of the bone shaft after marrow ablation of 2 month old BSP+/+ and BSP-/- mice. At d3, the ablated area in BSP-/- femurs showed higher vessel density (×4) and vascular volume (×7) than BSP+/+. Vessel numbers in the shaft of ablated BSP+/+ mice reached BSP-/- values only by d8, but with a vascular volume which was twice the value in BSP-/-, reflecting smaller vessel size in ablated mutants. At d6, a much higher number of Lin- (×3) as well as LSK (Lin- IL-7Rα- Sca-1hi c-Kithi , ×2) and hematopoietic stem cells (HSC: Flt3- LSK, ×2) were counted in BSP-/- marrow, indicating a faster recolonization. However, the proportion of LSK and HSC within the Lin- was lower in BSP-/- and more differentiated stages were more abundant, as also observed in unablated bone, suggesting that hematopoietic differentiation is favored in the absence of BSP. Interestingly, unablated BSP-/- femur marrow also contains more blood vessels than BSP+/+, and in both intact and ablated shafts expression of VEGF and OPN are higher, and DMP1 lower in the mutants. In conclusion, bone marrow ablation in BSP-/- mice is followed by a faster vascular and hematopoietic recolonization, along with lower medullary bone formation. Thus, lack of BSP affects the interplay between hematopoiesis, angiogenesis, and osteogenesis, maybe in part through higher expression of VEGF and the angiogenic SIBLING, OPN. J. Cell. Physiol. 232: 2528-2537, 2017. © 2016 Wiley Periodicals, Inc.
Assuntos
Medula Óssea/irrigação sanguínea , Medula Óssea/metabolismo , Fêmur/irrigação sanguínea , Fêmur/metabolismo , Hematopoese , Células-Tronco Hematopoéticas/metabolismo , Sialoproteína de Ligação à Integrina/deficiência , Neovascularização Fisiológica , Osteogênese , Técnicas de Ablação , Animais , Biomarcadores/metabolismo , Medula Óssea/patologia , Medula Óssea/cirurgia , Proliferação de Células , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Fêmur/patologia , Fêmur/cirurgia , Genótipo , Células-Tronco Hematopoéticas/patologia , Sialoproteína de Ligação à Integrina/genética , Masculino , Camundongos Knockout , Osteopontina/genética , Osteopontina/metabolismo , Fenótipo , Transdução de Sinais , Fatores de Tempo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Osteopontin (OPN) and bone sialoprotein (BSP) are coexpressed in osteoblasts and osteoclasts, and display overlapping properties. We used daily injection of parathyroid hormone 1-84 (iPTH) over the calvaria of BSP knockout (-/-) mice to investigate further their functional specificity and redundancy. iPTH stimulated bone formation in both +/+ and -/- mice, increasing to the same degree periosteum, osteoid and total bone thickness. Expression of OPN, osterix, osteocalcin (OCN) and DMP1 was also increased by iPTH in both genotypes. In contrast to +/+, calvaria cell cultures from -/- mice revealed few osteoblast colonies, no mineralization and little expression of OCN, MEPE or DMP1. In contrast, OPN levels were 5× higher in -/- versus +/+ cultures. iPTH increased alkaline phosphatase (ALP) activity in cell cultures of both genotypes, with higher OCN and the induction of mineralization in -/- cultures. siRNA blocking of OPN expression did not alter the anabolic action of the hormone in BSP +/+ calvaria, while it blunted iPTH effects in -/- mice, reduced to a modest increase in periosteum thickness. In -/- (not +/+) cell cultures, siOPN blocked the stimulation by iPTH of ALP activity and OCN expression, as well as the induction of mineralization. Thus, full expression of either OPN or BSP is necessary for the anabolic effect of PTH at least in the ectopic calvaria injection model. This suggests that OPN may compensate for the lack of BSP in the response to this hormonal challenge, and provides evidence of functional overlap between these cognate proteins.
Assuntos
Sialoproteína de Ligação à Integrina/genética , Osteogênese/genética , Osteopontina/genética , Crânio/crescimento & desenvolvimento , Animais , Células Cultivadas , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Sialoproteína de Ligação à Integrina/antagonistas & inibidores , Sialoproteína de Ligação à Integrina/biossíntese , Camundongos , Osteogênese/efeitos dos fármacos , Osteopontina/antagonistas & inibidores , Osteopontina/biossíntese , Hormônio Paratireóideo/administração & dosagem , RNA Mensageiro/metabolismo , Crânio/efeitos dos fármacosRESUMO
Matrix proteins of the SIBLING family interact with bone cells, extracellular matrix and mineral and are thus in a key position to regulate the microenvironment of the bone tissue, including its hematopoietic component. In this respect, osteopontin (OPN) has been implicated in the hematopoietic stem cell (HSC) niche as negative regulator of the HSC function. We investigated the impact on hematopoietic regulation of the absence of the cognate bone sialoprotein (BSP). BSP knockout (-/-) mice display increased bone marrow cellularity, and an altered commitment of hematopoietic precursors to myeloid lineages, leading in particular to an increased frequency of monocyte/macrophage cells. The B cell pool is increased in -/- bone marrow, and its composition is shifted toward more mature lymphocyte stages. BSP-null mice display a decreased HSC fraction among LSK cells and a higher percentage of more committed progenitors as compared to +/+. The fraction of proliferating LSK progenitors is higher in -/- mice, and after PTH treatment the mutant HSC pool is lower than in +/+. Strikingly, circulating levels of OPN as well as its expression in the bone tissue are much higher in the -/-. Thus, a BSP-null bone microenvironment affects the hematopoietic system both quantitatively and qualitatively, in a manner in part opposite to the OPN knockout, suggesting that the effects might in part reflect the higher OPN expression in the absence of BSP.