RESUMO
BACKGROUND: At an interim analysis (median follow-up, 6.2 months; n = 187), the phase 3 COSMIC-311 trial met the primary end point of progression-free survival (PFS): cabozantinib improved PFS versus a placebo (median, not reached vs. 1.9 months; p < .0001) in patients with previously treated radioiodine-refractory differentiated thyroid cancer (RAIR-DTC). The results from an exploratory analysis using an extended datacut are presented. METHODS: Patients 16 years old or older with RAIR-DTC who progressed on prior lenvatinib and/or sorafenib were randomized 2:1 to oral cabozantinib tablets (60 mg/day) or a placebo. Placebo patients could cross over to open-label cabozantinib upon radiographic disease progression. The objective response rate (ORR) in the first 100 randomized patients and the PFS in the intent-to-treat population, both according to Response Evaluation Criteria in Solid Tumors version 1.1 by blinded, independent review, were the primary end points. RESULTS: At the data cutoff (February 8, 2021), 258 patients had been randomized (cabozantinib, n = 170; placebo, n = 88); the median follow-up was 10.1 months. The median PFS was 11.0 months (96% confidence interval [CI], 7.4-13.8 months) for cabozantinib and 1.9 months (96% CI, 1.9-3.7 months) for the placebo (hazard ratio, 0.22; 96% CI, 0.15-0.32; p < .0001). The ORR was 11.0% (95% CI, 6.9%-16.9%) versus 0% (95% CI, 0.0%-4.1%) (p = .0003) with one complete response with cabozantinib. Forty placebo patients crossed over to open-label cabozantinib. Grade 3/4 treatment-emergent adverse events occurred in 62% and 28% of the cabozantinib- and placebo-treated patients, respectively; the most common were hypertension (12% vs. 2%), palmar-plantar erythrodysesthesia (10% vs. 0%), and fatigue (9% vs. 0%). There were no grade 5 treatment-related events. CONCLUSIONS: At extended follow-up, cabozantinib maintained superior efficacy over a placebo in patients with previously treated RAIR-DTC with no new safety signals.
Assuntos
Adenocarcinoma , Antineoplásicos , Neoplasias da Glândula Tireoide , Humanos , Adolescente , Radioisótopos do Iodo/uso terapêutico , Anilidas/efeitos adversos , Piridinas/efeitos adversos , Neoplasias da Glândula Tireoide/tratamento farmacológico , Neoplasias da Glândula Tireoide/radioterapia , Adenocarcinoma/tratamento farmacológico , Antineoplásicos/uso terapêuticoRESUMO
BACKGROUND: Albumin-bilirubin (ALBI) grade is an objective measure of liver function for patients with hepatocellular carcinoma (HCC). The tyrosine kinase inhibitor cabozantinib is approved for patients with advanced HCC who have received prior sorafenib based on the phase 3 CELESTIAL trial (NCT01908426). Cabozantinib improved overall survival (OS) and progression-free survival (PFS) versus placebo in patients with previously treated HCC. METHODS: Patients were randomised 2:1 to receive cabozantinib 60 mg or placebo orally every day. Clinical outcomes in patients with ALBI grade 1 or 2 at baseline were evaluated in CELESTIAL. ALBI scores were retrospectively calculated based on baseline serum albumin and total bilirubin, with an ALBI grade of 1 defined as ≤ -2.60 score and a grade of 2 as a score of > -2.60 to ≤ -1.39. RESULTS: Cabozantinib improved OS and PFS versus placebo in both ALBI grade 1 (hazard ratio [HR] [95% CI]: 0.63 [0.46-0.86] and 0.42 [0.32-0.56]) and ALBI grade 2 (HR [95% CI]: 0.84 [0.66-1.06] and 0.46 [0.37-0.58]) subgroups. Adverse events were consistent with those in the overall population. Rates of grade 3/4 adverse events associated with hepatic decompensation were generally low and were more common among patients in the ALBI grade 2 subgroup. DISCUSSION: These results provide initial support of cabozantinib in patients with advanced HCC irrespective of ALBI grade 1 or 2. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov number, NCT01908426.
Assuntos
Anilidas/administração & dosagem , Bilirrubina/análise , Carcinoma Hepatocelular/tratamento farmacológico , Neoplasias Hepáticas/tratamento farmacológico , Piridinas/administração & dosagem , Albumina Sérica/análise , Administração Oral , Adulto , Idoso , Idoso de 80 Anos ou mais , Anilidas/efeitos adversos , Carcinoma Hepatocelular/sangue , Feminino , Humanos , Testes de Função Hepática , Neoplasias Hepáticas/sangue , Masculino , Pessoa de Meia-Idade , Piridinas/efeitos adversos , Estudos Retrospectivos , Análise de Sobrevida , Resultado do TratamentoRESUMO
BACKGROUND: Patients with hepatocellular carcinoma (HCC) and Child-Pugh B liver cirrhosis have poor prognosis and are underrepresented in clinical trials. The CELESTIAL trial, in which cabozantinib improved overall survival (OS) and progression-free survival (PFS) versus placebo in patients with HCC and Child-Pugh A liver cirrhosis at baseline, was evaluated for outcomes in patients who had Child-Pugh B cirrhosis at Week 8. METHODS: This was a retrospective analysis of adult patients with previously treated advanced HCC. Child-Pugh B status was assessed by the investigator. Patients were randomised 2:1 to cabozantinib (60 mg once daily) or placebo. RESULTS: Fifty-one patients receiving cabozantinib and 22 receiving placebo had Child-Pugh B cirrhosis at Week 8. Safety and tolerability of cabozantinib for the Child-Pugh B subgroup were consistent with the overall population. For cabozantinib- versus placebo-treated patients, median OS from randomisation was 8.5 versus 3.8 months (HR 0.32, 95% CI 0.18-0.58), median PFS was 3.7 versus 1.9 months (HR 0.44, 95% CI 0.25-0.76), and best response was stable disease in 57% versus 23% of patients. CONCLUSIONS: These encouraging results with cabozantinib support the initiation of prospective studies in patients with advanced HCC and Child-Pugh B liver function. CLINICAL TRIAL REGISTRATION: NCT01908426.
Assuntos
Antineoplásicos , Carcinoma Hepatocelular , Neoplasias Hepáticas , Adulto , Anilidas , Antineoplásicos/efeitos adversos , Carcinoma Hepatocelular/patologia , Humanos , Cirrose Hepática/tratamento farmacológico , Neoplasias Hepáticas/patologia , Estudos Prospectivos , Piridinas , Estudos RetrospectivosRESUMO
RATIONALE: Gamma aminobutyric acid (GABA), a neurotransmitter of the central nervous system, is found in the systemic circulation of humans at a concentration between 0.5 and 3 µmol/L. However, the potential source of circulating GABA and its significance on the vascular system remains unknown. We hypothesized that endothelial cells (ECs) may synthesize and release GABA to modulate some functions in the EC and after its release into the circulation. OBJECTIVE: To assess whether GABA is synthesized and released by the EC and its potential functions. METHODS AND RESULTS: Utilizing the human umbilical vein ECs and aortic ECs, we demonstrated for the first time that ECs synthesize and release GABA from [1-(14)C]glutamate. Localization of GABA and the presence of the GABA-synthesizing enzyme, glutamic acid decarboxylase in EC were confirmed by immunostaining and immunoblot analysis, respectively. The presence of GABA was further confirmed by immunohistochemistry in the EC lining the human coronary vessel. EC-derived GABA regulated the key mechanisms of ATP synthesis, fatty acid, and pyruvate oxidation in EC. GABA protected EC by inhibiting the reactive oxygen species generation and prevented monocyte adhesion by attenuating vascular cell adhesion molecule -1 and monocyte chemoattractant protein-1 expressions. GABA had no relaxing effect on rat aortic rings. GABA exhibited a dose-dependent fall in blood pressure. However, the fall in BP was abolished after pretreatment with pentolinium. CONCLUSIONS: Our findings indicate novel potential functions of endothelium-derived GABA.
Assuntos
Células Endoteliais/metabolismo , Ácido gama-Aminobutírico/biossíntese , Ácido gama-Aminobutírico/metabolismo , Animais , Aorta/efeitos dos fármacos , Aorta/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Masculino , Técnicas de Cultura de Órgãos , Ratos , Ratos Sprague-Dawley , Ácido gama-Aminobutírico/farmacologiaRESUMO
In this study, we have identified cystathionine (CTH), a sulfur containing metabolite, to be selectively enriched in human breast cancer (HBC) tissues (â¼50-100 pmoles/mg protein) compared with undetectable levels in normal breast tissues. The accumulation of CTH, specifically in HBC, was attributed to the overexpression of cystathionine beta synthase (CBS), its synthesizing enzyme, and the undetectable levels of its downstream metabolizing enzyme, cystathionine gamma lyase (CGL). Interestingly both CBS and CGL could not be detected in normal breast tissues. We further observed that CTH protected HBC cells against excess reactive oxygen species (ROS) and chemotherapeutic drug-induced apoptosis. Moreover, CTH promoted both mitochondrial and endoplasmic reticulum homeostasis in HBC cells. As both the mitochondria and the endoplasmic reticulum are key organelles regulating the onset of apoptosis, we reasoned that endogenous CTH could be contributing towards increasing the apoptotic threshold in HBC cells. An increased apoptotic threshold is a hallmark of all cancer types, including HBC, and is primarily responsible for drug resistance. Hence this study unravels one of the possible pathways that may contribute towards drug resistance in HBC.
Assuntos
Neoplasias da Mama/metabolismo , Cistationina beta-Sintase/metabolismo , Cistationina gama-Liase/metabolismo , Cistationina/metabolismo , Resistencia a Medicamentos Antineoplásicos , Antineoplásicos/química , Apoptose , Linhagem Celular Tumoral , Sobrevivência Celular , Citosol/metabolismo , Retículo Endoplasmático/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Células MCF-7 , Microscopia Eletrônica , Consumo de Oxigênio , Permeabilidade , Espécies Reativas de Oxigênio/metabolismoRESUMO
Gestational diabetes, pre-eclampsia as well as intra-uterine infection during pregnancy affects the function of the endothelium both in the mother and the fetus leading to endothelial dysfunction. Gestational diabetes is also associated with an increased incidence of pre-eclampsia and it is likely that both the hyperglycemia as well as the release of cytokines especially TNFα during hyperglycemia may play an important role in the pathogenesis of endothelial dysfunction leading to preeclampsia. Similarly, some but not all studies have suggested that infection of the mother under certain circumstances can also lead to preeclampsia as women with either a bacterial or viral infection were at a higher risk of developing preeclampsia, compared to women without infection and infection also leads to a release in TNFα. Endothelial cells exposed to either high glucose or TNFα leads to an increase in the production of H2O2 and to a decrease in endothelial cell proliferation. The cellular and molecular mechanisms involved in this phenomenon are discussed.Gestational diabetes, pre-eclampsia as well as intra-uterine infection during pregnancy has profound effects on the fetus and long term effects on the neonate. All three conditions affect the function of the endothelium both in the mother and the fetus leading to endothelial dysfunction. Gestational diabetes is also associated with an increased incidence of pre-eclampsia and it is likely that both the hyperglycemia as well as the release of cytokines especially TNFα during hyperglycemia may play an important role in the pathogenesis of endothelial dysfunction leading to preeclampsia. It has also been suggested although not universally accepted that under certain circumstances maternal infection may also predispose to pre-eclampsia. Pre-eclampsia is also associated with the release of TNFα and endothelial dysfunction. However, the cellular and molecular mechanism(s) leading to the endothelial dysfunction by either hyperglycemia or by the cytokine TNFα appear to be different. In this chapter, we explore some of the similarities and differences leading to endothelial dysfunction by both hyperglycemia and by the inflammatory cytokine TNFα and the cellular and molecular mechanism(s) involved.
Assuntos
Citocinas/imunologia , Diabetes Gestacional/imunologia , Endotélio Vascular/imunologia , Pré-Eclâmpsia/imunologia , Complicações Infecciosas na Gravidez/imunologia , Diabetes Gestacional/metabolismo , Endotélio Vascular/metabolismo , Feminino , Humanos , Pré-Eclâmpsia/metabolismo , Gravidez , Complicações Infecciosas na Gravidez/metabolismoRESUMO
It is established that high concentrations of nitric oxide(1) (NO), as released from activated macrophages, induce apoptosis in breast cancer cells. In this study, we assessed the potential of a light-activated NO donor [(Me2bpb)Ru(NO)(Resf)], a recently reported apoptototic agent, in suppressing the anchorage independent growth potentials of an aggressive human breast cancer cell line. Our results demonstrated the down regulation of anchorage independent growth by light activated NO treatment in the aggressive human breast cancer cell line MDA-MB-231 and afforded insight into the associated mechanism(s). The investigation revealed an up-regulation of the bioactivity of catalase with an accompanied reduction in the endogenous levels of H2O2, a direct substrate of catalase and a recently identified endogenous growth modulator in breast cancer cells. An earlier publication reported that endogenous superoxide (O2(-)) in human breast cancer cells constitutively inhibits catalase bioactivity (at the level of its protein), resulting in increased H2O2 levels. Interestingly in this study, O2(-) was also found to be down- regulated following NO treatment providing a basis for the observed increase in catalase bioactivity. Cells silenced for the catalase gene exhibited compromised reduction in anchorage independent growth upon light activated NO treatment. Collectively this study detailed a mechanistic cross talk between exogenous NO and endogenous ROS in attenuating anchorage independent growth.
Assuntos
Peróxido de Hidrogênio/metabolismo , Luz , Óxido Nítrico/metabolismo , Compostos Organometálicos/farmacologia , Superóxidos/metabolismo , Neoplasias da Mama/patologia , Catalase/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Ensaio de Unidades Formadoras de Colônias , Humanos , Óxido Nítrico/química , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Fosforilação/efeitos dos fármacos , Fosforilação/efeitos da radiação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Superóxido Dismutase/metabolismo , Tirosina/análogos & derivados , Tirosina/biossínteseRESUMO
OBJECTIVE: Tumor necrosis factor-α (TNFα) may change from a stimulator of reversible activation of endothelial cells (ECs) to a killer when combined with cycloheximide (CHX). The means by which endothelial cells are destined to either the survival pathway or the apoptotic pathway are not fully understood. We investigated the role of p38 mitogen-activated protein kinase (MAPK) and protein phosphatase 2A (PP2A) activation and their regulation of 4E-BP1 stability in ECs to determine whether this pathway contributes to apoptosis induced by TNFα and CHX. METHODS AND RESULTS: Apoptosis was induced in human umbilical vein ECs (HUVECs) by treating them with a combination of TNFα and CHX (TNFα/CHX). Activation of p38 MAPK was increased in HUVECs undergoing apoptosis, which was associated with degradation of eukaryotic initiation factor 4A regulator 4E-BP1 in a p38 MAPK-dependent manner. CHX attenuated a TNFα-stimulated increase in the expression and activity of PP2A. Silencing PP2A expression with small interfering RNA transfection mimicked CHX sensitization, increasing HUVEC apoptosis with TNFα stimulation and suggesting a protective role for PP2A in the apoptotic process. CONCLUSION: Our data suggest that (1) TNFα stimulates PP2A and HUVECs elude apoptosis by PP2A-dependent dephosphorylation of p38 MAPK, and (2) CHX-induced inhibition of PP2A leads to maintenance of p38 activity and degradation of 4E-BP1, resulting in enhanced TNFα-induced apoptosis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Fosfoproteínas/metabolismo , Proteína Fosfatase 2/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Proteínas de Ciclo Celular , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células Cultivadas , Cicloeximida/farmacologia , Endotélio Vascular/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Fator de Iniciação 4E em Eucariotos/metabolismo , Humanos , Imidazóis/farmacologia , Proteína Fosfatase 2/antagonistas & inibidores , Proteína Fosfatase 2/efeitos dos fármacos , Piridinas/farmacologia , RNA Interferente Pequeno/farmacologia , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Introduction: Immune checkpoint inhibitors (ICI) have shown great promise in a wide spectrum of malignancies. However, responses are not always durable, and this mode of treatment is only effective in a subset of patients. As such, there exists an unmet need for novel approaches to bolster ICI efficacy.Areas covered: We review the role of the Tyro3, Axl, and Mer (TAM) receptor tyrosine kinases in promoting tumor-induced immune suppression and discuss the benefits that may be derived from combining ICI with TAM kinase-targeted tyrosine kinase inhibitors. We searched the MEDLINE Public Library of Medicine (PubMed) and EMBASE databases and referred to ClinicalTrials.gov for relevant ongoing studies.Expert opinion: Targeting of TAM kinases may improve the efficacy of immune checkpoint blockade. However, it remains to be determined whether this effect will be better achieved by the selective targeting of each TAM receptor, depending on the context, or by multi-receptor TAM inhibitors. Triple inhibition of all TAM receptors is more likely to be associated with an increased risk for adverse events. Clinical trial designs should use high-resolution clinical endpoints and proper control arms to determine the synergistic effects of combining TAM inhibition with immune checkpoint blockade.
Assuntos
Antineoplásicos/farmacologia , Inibidores de Checkpoint Imunológico/farmacologia , Neoplasias/tratamento farmacológico , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/efeitos adversos , Ensaios Clínicos como Assunto/métodos , Sinergismo Farmacológico , Humanos , Inibidores de Checkpoint Imunológico/administração & dosagem , Inibidores de Checkpoint Imunológico/efeitos adversos , Terapia de Alvo Molecular , Neoplasias/imunologia , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/metabolismo , c-Mer Tirosina Quinase/antagonistas & inibidores , c-Mer Tirosina Quinase/metabolismo , Receptor Tirosina Quinase AxlRESUMO
Photo-activatable carbon monoxide (CO)-releasing molecules (photoCORMs), have recently provided help to identify the salutary effects of CO in human pathophysiology. Among them notable is the ability of CO to sensitize chemotherapeutic-resistant cancer cells. Findings from our group have shown CO to mitigate drug resistance in certain cancer cells by the inhibition of cystathionine ß-synthase (CBS), a key regulator of redox homeostasis in the cell. Diminution of the antioxidant capacity of cancer cells leads to sensitization to reactive oxygen species-producing drugs like doxorubicin and paclitaxel upon cotreatment with CO as well as in mitigating the drug effects of cisplatin. We hypothesize that the development of CO delivery techniques for coadministration with existing cancer treatment regimens may ultimately improve clinical outcomes in cancer therapy.
Assuntos
Antineoplásicos/farmacologia , Monóxido de Carbono/metabolismo , Cistationina beta-Sintase/antagonistas & inibidores , Doxorrubicina/farmacologia , Neoplasias/tratamento farmacológico , Paclitaxel/farmacologia , Cistationina beta-Sintase/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Neoplasias/metabolismo , Neoplasias/patologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Carbon monoxide (CO)-releasing antibody conjugates were synthesized utilizing a photoactivatable CO-releasing molecule (photoCORM) and mouse monoclonal antibodies linked by a biotin-streptavidin system. Different monoclonal antibodies raised against different surface-expressed antigens that are implicated in ovarian cancer afforded a family of antibody-photoCORM conjugates (Ab-photoCORMs). In an immunosorbent/cell viability assay, Ab-photoCORMs accumulated onto ovarian cancer cells expressing the target antigens, delivering cytotoxic doses of CO in vitro. The results described here provide the first example of an "immunoCORM", a proof-of-the-concept antibody-drug conjugate that delivers a gaseous molecule as a warhead to ovarian cancer.
RESUMO
Cisplatin resistance remains a major impediment to effective treatment of ovarian cancer. Despite initial platinum responsiveness, thiol-containing peptides and proteins, glutathione (GSH) and metallothionein (MT), bind and inactivate cisplatin in cancer cells. Indeed, high levels of GSH and MT in ovarian cancers impart cisplatin resistance and are predictive of poor prognosis. Cystathionine ß-synthase (CBS), an enzyme involved in sulfur metabolism, is overexpressed in ovarian cancer tissues and is itself associated with cisplatin resistance. Treatment with exogenous carbon monoxide (CO), a known inhibitor of CBS, may mitigate cisplatin resistance in ovarian cancer cells by attenuation of GSH and MT levels. Using a photo-activated CO-releasing molecule (photoCORM), [Mn(CO)3(phen)(PTA)]CF3SO3 (phenâ¯=â¯1,10-phenanthroline, PTAâ¯=â¯1,3,5-triza-7-phosphaadamantane) we assessed the ability of CO to sensitize established cisplatin-resistant ovarian cancer cell lines to cisplatin. Cisplatin-resistant cells, treated with both cisplatin and CO, exhibited significantly lower cell viability and increased poly (ADP-ribose) polymerase (PARP) cleavage versus those treated with cisplatin alone. These cisplatin-resistant cell lines overexpressed CBS and had increased steady state levels of GSH and expression of nuclear MT. Both CO treatment and lentiviral-mediated silencing of CBS attenuated GSH and nuclear MT expression in cisplatin resistant cells. We have demonstrated that CO, delivered from a photoCORM, sensitizes established cisplatin-resistant cell lines to cisplatin. Furthermore, we have presented strong evidence that the effects of CO in circumventing chemotherapeutic drug resistance is at least in part mediated by the inactivation of endogenous CBS.
Assuntos
Antineoplásicos/farmacologia , Monóxido de Carbono/farmacologia , Cisplatino/farmacologia , Glutationa/metabolismo , Metalotioneína/metabolismo , Neoplasias Ovarianas/patologia , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Cistationina beta-Sintase/antagonistas & inibidores , Cisteína/metabolismo , Resistencia a Medicamentos Antineoplásicos , Feminino , Humanos , Neoplasias Ovarianas/enzimologia , Neoplasias Ovarianas/metabolismoRESUMO
Context: Biochemical weakening of the amnion is a major factor preceding preterm premature rupture of membranes (PPROMs), leading to preterm birth. Activation of matrix metalloproteinases (MMPs) is known to play a key role in collagen degradation of the amnion; however, epithelial to mesenchymal transition (EMT) that is also induced by MMP activation has not been investigated as a mechanism for amnion weakening. Objective: To measure amniotic EMT associated with vaginal delivery (VD) compared with unlabored cesarean sections (CSs), and to assess changes in amniotic mechanical strength with pharmacologic inhibitors and inducers of EMT, thus testing the hypothesis that EMT is a key biochemical event that promotes amniotic rupture. Findings: (1) Amnions taken from VD contained a significantly increased number of mesenchymal cells relative to epithelial cells compared with unlabored CS by fluorescence-activated cell sorting analysis (60% vs 10%); (2) tumor necrosis factor (TNF)-α stimulation of amniotic epithelial cells increased expression of the mesenchymal marker vimentin after 2 days; (3) EMT inhibitor, etodolac, significantly increased the time and mechanical pressure required to rupture the amnion; and (4) TNF-α and another pharmacologic EMT inducer, ethacridine, decreased the time and mechanical pressure required for amnion rupture, further confirming that the mesenchymal phenotype significantly weakens the amnion. Conclusions: This work demonstrated amniotic cell EMT was associated with labor and EMT decreased the tensile strength of the amnion. These findings suggest a role for EMT in the pathophysiology of PPROM and may provide a basis for development of therapies to prevent preterm labor.
Assuntos
Âmnio/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Ruptura Prematura de Membranas Fetais/metabolismo , Resistência à Tração/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Âmnio/metabolismo , Inibidores de Ciclo-Oxigenase 2/farmacologia , Etodolac/farmacologia , Feminino , Humanos , Metaloproteinases da Matriz/metabolismo , GravidezRESUMO
Drug resistance is a major impediment to effective treatment of breast cancer. Compared to normal cells, cancer cells have an increased antioxidant potential due to an increased ratio of reduced to oxidized glutathione (GSH/GSSG). This is known to confer therapeutic resistance. Here, we have identified a mechanism, unique to breast cancer cells, whereby cystathionine ß-synthase (CBS) promotes elevated GSH/GSSG. Lentiviral silencing of CBS in human breast cancer cells attenuated GSH/GSSG, total GSH, nuclear factor erythroid 2-related factor 2 (Nrf2), and processes downstream of Nrf2 that promote GSH synthesis and regeneration of GSH from GSSG. Carbon monoxide (CO) reduced GSH/GSSG in three breast cancer cell lines by inhibiting CBS. Furthermore, CO sensitized breast cancer cells to doxorubicin. These results provide insight into mechanism(s) by which CBS increases the antioxidant potential and the ability for CO to inhibit CBS activity to alter redox homeostasis in breast cancer, increasing sensitivity to a chemotherapeutic.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Antioxidantes/metabolismo , Neoplasias da Mama/metabolismo , Monóxido de Carbono/metabolismo , Cistationina beta-Sintase/antagonistas & inibidores , Antibióticos Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Doxorrubicina/farmacologia , Sinergismo Farmacológico , Feminino , Inativação Gênica/efeitos dos fármacos , Glutationa/metabolismo , Humanos , Fator 2 Relacionado a NF-E2/metabolismoRESUMO
Human cystathionine beta-synthase plays a key role in maintaining low intracellular levels of homocysteine and is unique in being a pyridoxal phosphate-dependent enzyme that is a hemeprotein. It catalyzes the beta-replacement of serine and homocysteine to generate the condensation product, cystathionine. While the structure of a truncated catalytic core of the protein has been determined by crystallography, a model for the full-length enzyme has been developed guided by hydrogen-deuterium exchange mass spectrometric and docking studies. In this review, we have utilized the available structural models for human cystathionine beta-synthase to conduct a structure-function analysis of a select group of pathogenic mutations described in patients with hereditary hyperhomocysteinemia.
Assuntos
Cistationina beta-Sintase/química , Heme/metabolismo , Mutação , Catálise , Cistationina beta-Sintase/genética , Cistationina beta-Sintase/metabolismo , Humanos , Modelos Moleculares , Conformação ProteicaRESUMO
Accumulating evidence suggests that abnormal levels of homocysteine are associated with vascular dysfunctions, cancer cell proliferation and various neurodegenerative diseases. With respect to the latter, a perturbation of transition metal homeostasis and an inhibition of catalase bioactivity have been reported. Herein, we report on some of the molecular bases for the cellular toxicity of homocysteine and demonstrate that it induces the formation of sulfcatalase, an irreversible inactive state of the enzyme, without the intervention of hydrogen sulfide. Initially, homocysteine reacts with native catalase and/or redox-active transition metal ions to generate thiyl radicals that mediate compound II formation, a temporarily inactive state of the enzyme. Then, the ferryl centre of compound II intervenes into the unprecedented S-oxygenation of homocysteine to engender the corresponding sulfenic acid species that further participates into the prosthetic heme modification through the formation of an unusual Fe(II) sulfonium. In addition, our ex cellulo studies performed on cancer cells, models of neurodegenerative diseases and ulcerative colitis suggest the likelihood of this scenario in a subset of cancer cells, as well as in a cellular model of Parkinson's disease. Our findings expand the repertoire of heme modifications promoted by biological compounds and point out another deleterious trait of disturbed homocysteine levels that could participate in the aetiology of these diseases.
Assuntos
Catalase/metabolismo , Heme/análogos & derivados , Homocisteína/metabolismo , Neoplasias/metabolismo , Doenças Neurodegenerativas/metabolismo , Oxigênio/metabolismo , Animais , Catalase/antagonistas & inibidores , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Ativação Enzimática/efeitos dos fármacos , Heme/química , Heme/metabolismo , Sulfeto de Hidrogênio/metabolismo , Ferro/metabolismo , Masculino , Espectrometria de Massas , Camundongos Endogâmicos C57BL , Neoplasias/patologia , Oxirredução , Compostos de Sulfidrila/farmacologiaRESUMO
Chromogranin A (CgA), a neuroendocrine secretory protein, and its fragments are present in variable amounts in the blood of normal subjects and cancer patients. We investigated whether circulating CgA has a regulatory function in tumor biology and progression. Systemic administration of full-length CgA, but not of fragments lacking the C-terminal region, could reduce tumor growth in murine models of fibrosarcoma, mammary adenocarcinoma, Lewis lung carcinoma, and primary and metastatic melanoma, with U-shaped dose-response curves. Tumor growth inhibition was associated with reduction of microvessel density and blood flow in neoplastic tissues. Neutralization of endogenous CgA with antibodies against its C-terminal region (residues 410-439) promoted tumor growth. Structure-function studies showed that the C-terminal region of CgA contains a bioactive site and that cleavage of this region causes a marked loss of anti-angiogenic and anti-tumor potency. Mechanistic studies showed that full-length CgA could induce, with a U-shaped dose-response curve, the production of protease nexin-1 in endothelial cells, a serine protease inhibitor endowed of anti-angiogenic activity. Gene silencing or neutralization of protease nexin-1 with specific antibodies abolished both anti-angiogenic and anti-tumor effects of CgA. These results suggest that circulating full-length CgA is an important inhibitor of angiogenesis and tumor growth, and that cleavage of its C-terminal region markedly reduces its activity. Pathophysiological changes in CgA blood levels and/or its fragmentation might regulate disease progression in cancer patients.
Assuntos
Cromogranina A/sangue , Neoplasias/sangue , Neoplasias/patologia , Inibidores da Angiogênese/farmacologia , Animais , Anticorpos Neutralizantes/farmacologia , Antineoplásicos/farmacologia , Biomarcadores , Linhagem Celular Tumoral , Cromogranina A/farmacologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Ensaio de Imunoadsorção Enzimática , Feminino , Inativação Gênica , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Melanoma Experimental , Camundongos , Neoplasias/genética , Neovascularização Patológica/tratamento farmacológico , Testes de Neutralização , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/farmacologia , Proteínas Recombinantes , Serpina E2/genética , Serpina E2/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Aggressive cancers exhibit an efficient conversion of high amounts of glucose to lactate accompanied by acid secretion, a phenomenon popularly known as the Warburg effect. The acidic microenvironment and the alkaline cytosol create a proton-gradient (acid gradient) across the plasma membrane that represents proton-motive energy. Increasing experimental data from physiological relevant models suggest that acid gradient stimulates tumor proliferation, and can also support its energy needs. However, direct biochemical evidence linking extracellular acid gradient to generation of intracellular ATP are missing. In this work, we demonstrate that cancer cells can synthesize significant amounts of phosphate-bonds from phosphate in response to acid gradient across plasma membrane. The noted phenomenon exists in absence of glycolysis and mitochondrial ATP synthesis, and is unique to cancer. Biochemical assays using viable cancer cells, and purified plasma membrane vesicles utilizing radioactive phosphate, confirmed phosphate-bond synthesis from free phosphate (Pi), and also localization of this activity to the plasma membrane. In addition to ATP, predominant formation of pyrophosphate (PPi) from Pi was also observed when plasma membrane vesicles from cancer cells were subjected to trans-membrane acid gradient. Cancer cytosols were found capable of converting PPi to ATP, and also stimulate ATP synthesis from Pi from the vesicles. Acid gradient created through glucose metabolism by cancer cells, as observed in tumors, also proved critical for phosphate-bond synthesis. In brief, these observations reveal a role of acidic tumor milieu as a potential energy source and may offer a novel therapeutic target.
Assuntos
Trifosfato de Adenosina/biossíntese , Membrana Celular/metabolismo , Citosol/metabolismo , Glucose/metabolismo , Prótons , Difosfato de Adenosina/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Difosfatos/metabolismo , Glicólise , Humanos , Concentração de Íons de Hidrogênio , Transporte de Íons , Cinética , Ácido Láctico/biossíntese , Fosfatos/metabolismo , Radioisótopos de FósforoRESUMO
Cystathionine ß-synthase (CBS) is an enzyme in the transulfuration pathway that can catalyze the condensation of homocysteine (Hcy) and cysteine (Cys) to hydrogen sulfide (H2S) and cystathionine (CTH). CBS-derived H2S is important in angiogenesis and drug resistance in colon and ovarian cancers, respectively. However, the mechanisms by which cancer cell-derived H2S is utilized by cancer cells as a protective agent against host-derived activated macrophages are not yet investigated. This study investigated the mechanistic role of CBS-derived H2S in the protection of human breast cancer (HBC) cells against activated macrophages. HBC patient-derived tissue arrays and immunoblot analysis of HBC cells exhibited significantly increased levels of CBS when compared with their normal counterparts. This was associated with increased levels of H2S and CTH. Silencing of CBS in HBC cells caused a significant decrease in the levels of H2S and CTH but did not affect the growth of these cells per se, in in vitro cultures. However CBS-silenced cells exhibited significantly reduced growth in the presence of activated macrophages and in xenograft models. This was associated with an increase in the steady state levels of reactive aldehyde-derived protein adducts. Exogenous addition of H2S countered the effects of CBS silencing in the presence of macrophages. Conversely overexpression of CBS in human breast epithelial (HBE) cells (which do not naturally express CBS) protected them from activated macrophages, which were otherwise susceptible to the latter.
Assuntos
Neoplasias da Mama/enzimologia , Cistationina beta-Sintase/fisiologia , Animais , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Membrana Celular/enzimologia , Técnicas de Cocultura , Feminino , Glutationa/metabolismo , Humanos , Sulfeto de Hidrogênio/farmacologia , Metástase Linfática , Células MCF-7 , Macrófagos/imunologia , Camundongos Endogâmicos BALB C , Camundongos Nus , Transplante de NeoplasiasRESUMO
Endothelial cells in the utero-placental circulation play an important physiological role in maintaining the fetoplacental vessels in a vasodilated state as these vessels are non-innervated. These endothelial cells produce both prostacyclin and nitric oxide which in addition to causing vasodilation also prevent platelet aggregation and adhesion of platelets to endothelial cells. Most investigators are of the opinion that energy metabolism of endothelial cells and ATP generation is mainly glycolytic. Glycolytic activity in endothelial cells is increased during proliferation to maintain ATP at normal levels by an increase in the expression of the glucose transporter. More recent studies have reported the existence of a functional F1F0 ATP synthase on the surface of HUVEC and it has been found to be enzymatically active in the synthesis of ATP. Additional studies utilizing very early passage HUVEC need to be carried out to ascertain the relative contribution of oxidative phosphorylation compared with the glycolytic pathway for ATP synthesis in normal pregnancy as well as in abnormal states like preeclampsia, diabetes, intrauterine injection as well as intrauterine growth restriction.