RESUMO
Ultrasound (US) offers potentially important opportunities from a therapeutic point of view. Thus, the study of the biological effects of US on cancer cells is important to understand the consequences of these changes on the malignant phenotype. This study aimed to investigate the effects of low-intensity ultrasound (LIPUS) on the phenotype of colorectal cancer cell lines. Cell proliferation was evaluated by viability test and by evaluation of pERK expression, while cell motility using the scratch test. Cell differentiation was evaluated assessing alkaline phosphatase activity. Epithelial mesenchymal transition was assessed by analyzing the expression of Vimentin and E-Cadherin. Release and uptake of extracellular vesicles (EVs) were evaluated by flow cytometry. LIPUS effects on the organization of cytoskeleton were analyzed by confocal microscopy and by evaluation of Rho GTPase expression. No alterations in vitality and clonogenicity were observed when the intermediate (0.4 MPa) and the lowest (0.035 MPa) acoustic intensities were administered while the treatment with high intensity (1 MPa) induced a reduction of both cell viability and clonogenicity in both cell lines in a frequency-dependent manner. LIPUS promoted the differentiation of colon cancer cells, affected epithelial-to-mesenchymal transition, promoted the closure of a wound as well as increased the release of EVs compared with untreated cells. LIPUS-induced increase in cell motility was likely due to a Rho GTPase-dependent mechanism. Overall, the results obtained warrant further studies on the potential combined effect of LIPUS with differentiating agents and on their potential use in a clinical setting.
Assuntos
Proliferação de Células/efeitos da radiação , Neoplasias Colorretais/radioterapia , Osteogênese/efeitos da radiação , Ondas Ultrassônicas , Caderinas/genética , Diferenciação Celular/efeitos da radiação , Movimento Celular/efeitos da radiação , Sobrevivência Celular/efeitos da radiação , Células Cultivadas , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Transição Epitelial-Mesenquimal/efeitos da radiação , Vesículas Extracelulares/genética , Vesículas Extracelulares/efeitos da radiação , Regulação Neoplásica da Expressão Gênica/efeitos da radiação , Células HT29 , Humanos , Células-Tronco Mesenquimais/efeitos da radiação , Transdução de Sinais/efeitos da radiação , Proteínas rho de Ligação ao GTP/genéticaRESUMO
Antimicrobial resistance is one of the most serious global public health problems. Therefore, novel strategies are needed to counteract bacterial resistance development. The aim of the present study was to enhance the activity of antibiotics to bacteria by using ultrasound. Ultrasound reduced the dosage of ampicillin required to impair bacterial viability.
Assuntos
Ampicilina , Farmacorresistência Bacteriana , Staphylococcus aureus Resistente à Meticilina , Ultrassonografia , Ampicilina/administração & dosagem , Ampicilina/farmacologia , Antibacterianos/administração & dosagem , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos da radiação , Testes de Sensibilidade MicrobianaRESUMO
Subxiphoid puncture is considered the standard approach for epicardial ablation of ventricular arrhythmia, but in some cases this access is impracticable due to the patient's anatomy. We describe the case of a patient with electrical storm and abnormal subdiaphragmatic anatomy that precluded the usual subxiphoid approach. In this patient the pericardial space was gained through a direct thorax puncture at the fifth intercostals space close to the mammary line. The tools and technique utilized in this case were similar to what is usually used for traditional subxiphoid puncture. The thorax percutaneous puncture was successfully carried out without complication.
Assuntos
Ablação por Cateter/métodos , Ventrículos do Coração/cirurgia , Pericárdio/cirurgia , Punções/métodos , Taquicardia Ventricular/cirurgia , Procedimentos Cirúrgicos Torácicos/métodos , Fibrilação Ventricular/cirurgia , Mapeamento Epicárdico/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Taquicardia Ventricular/diagnóstico , Resultado do Tratamento , Fibrilação Ventricular/diagnósticoRESUMO
When performing epicardial ablation of ventricular tachycardia (VT), caution must be taken not to damage the coronary arteries. We report a case in which a new, nonfluoroscopic technique for incorporating an accurate, real-time reconstruction of the main coronary vessels into a three-dimensional electroanatomic map was used for epicardial VT ablation.
Assuntos
Ablação por Cateter/métodos , Angiografia Coronária/métodos , Vasos Coronários/diagnóstico por imagem , Mapeamento Epicárdico/métodos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/cirurgia , Idoso , Feminino , Fluoroscopia , Humanos , Técnica de Subtração , Cirurgia Assistida por Computador/métodos , Resultado do TratamentoRESUMO
Neuromedin U (NMU) is an endogenous peptide implicated in the regulation of feeding, energy homeostasis, and glycemic control, which is being considered for the therapy of obesity and diabetes. A key liability of NMU as a therapeutic is its very short half-life in vivo. We show here that conjugation of NMU to human serum albumin (HSA) yields a compound with long circulatory half-life, which maintains full potency at both the peripheral and central NMU receptors. Initial attempts to conjugate NMU via the prevalent strategy of reacting a maleimide derivative of the peptide with the free thiol of Cys34 of HSA met with limited success, because the resulting conjugate was unstable in vivo. Use of a haloacetyl derivative of the peptide led instead to the formation of a metabolically stable conjugate. HSA-NMU displayed long-lasting, potent anorectic, and glucose-normalizing activity. When compared side by side with a previously described PEG conjugate, HSA-NMU proved superior on a molar basis. Collectively, our results reinforce the notion that NMU-based therapeutics are promising candidates for the treatment of obesity and diabetes.
Assuntos
Fármacos Antiobesidade/síntese química , Hipoglicemiantes/síntese química , Neuropeptídeos/síntese química , Neuropeptídeos/farmacologia , Polietilenoglicóis/farmacologia , Albumina Sérica/síntese química , Animais , Fármacos Antiobesidade/farmacocinética , Fármacos Antiobesidade/farmacologia , Glicemia , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos , Humanos , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neuropeptídeos/farmacocinética , Polietilenoglicóis/farmacocinética , Receptores de Neurotransmissores/agonistas , Albumina Sérica/farmacocinética , Albumina Sérica/farmacologia , Albumina Sérica Humana , Redução de Peso/efeitos dos fármacosRESUMO
Transcatheter aortic valve implantation may be complicated by the development of conduction disturbances, including left bundle branch block and high-grade atrioventricular blocks, especially in patients with predisposing risk factors, such as pre-existing right bundle branch block. Permanent pacemaker implantation is a procedure with potential short- and long-term complications, and it should be reserved to patients with appropriate indications. Electrophysiological testing and/or prolonged ambulatory ECG monitoring are valuable tools for stratifying the risk of pacemaker implantation. However, the management of new-onset conduction disorders is not always straightforward, and there are different approaches depending on the center's attitude. Therefore, the purpose of this review is to define clinical management based on current evidence, while awaiting data from randomized trials.
Assuntos
Substituição da Valva Aórtica Transcateter , Humanos , Substituição da Valva Aórtica Transcateter/efeitos adversos , Incidência , Fatores de Risco , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Marca-Passo Artificial/efeitos adversos , Bloqueio de Ramo/etiologia , Bloqueio de Ramo/terapia , Bloqueio de Ramo/epidemiologia , Estenose da Valva Aórtica/cirurgia , Bloqueio Atrioventricular/terapia , Bloqueio Atrioventricular/etiologia , Bloqueio Atrioventricular/epidemiologiaRESUMO
The search for silent atrial tachyarrhythmias remains one of the cornerstones in patients suffering from embolic stroke of undetermined source. We report the case of a 76-year-old female patient suffering from recurrence of ischemic stroke, adequately selected based on the presence of predictors of atrial fibrillation (AF), to perform prolonged ECG monitoring. This recording allowed to document long-lasting AF triggered by atrial tachycardia. It was also possible to demonstrate a direct correlation between AF and new cerebral stroke.
Assuntos
Fibrilação Atrial , AVC Embólico , AVC Isquêmico , Acidente Vascular Cerebral , Taquicardia Supraventricular , Feminino , Humanos , Idoso , Fibrilação Atrial/complicações , Fatores de Risco , Eletrocardiografia , Acidente Vascular Cerebral/etiologiaRESUMO
The wearable cardioverter defibrillator (WCD) has been proven to be effective in preventing sudden cardiac death (SCD) in patients soon after acute myocardial infarction (AMI) and left ventricular ejection fraction (LVEF) ≤35%. The aim of this study was to assess whether a WCD may shorten the length of an initial hospital stay (total length, days in the intensive care unit (ICU) and in the acute cardiac care unit (ACCU)) among these patients. This was a single-centre, retrospective observational study of patients referred for the management of SCD risk post-AMI and LVEF ≤35%, in a tertiary care hospital. The clinical characteristics and length of index hospitalization of the group of patients discharged, with or without WCD, were compared. A propensity score analysis was performed, then weighted regression models were conducted. A total of 101 patients in the WCD group and 29 in the control group were enrolled in the analysis. In the weighted regression models, WCD significantly reduced the days spent in ACCU (p < 0.001). WCD patients had significantly fewer days spent in ACCU (5.5 ± 2.6 vs. 8.4 ± 12.8 days, p < 0.001) and shorter hospitalizations (10.2 ± 5.7 vs. 13.4 ± 17.6 days, p = 0.005), compared with the control group. It was concluded that the WCD appears to reduce the total length of hospitalization and lengths of stay in ACCU for patients post-AMI and with left ventricular dysfunction.
RESUMO
Novel effective therapeutic strategies are needed to treat brain neurodegenerative diseases and to improve the quality of life of patients affected by Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Amyotrophic Lateral sclerosis (ALS) as well as other brain conditions. At present no effective treatment options are available; current therapeutics for neurodegenerative diseases (NDs) improve cognitive symptoms only transiently and in a minor number of patients. Further, most of the amyloid-based phase III clinical trials recently failed in AD, in spite of promising preclinical and phase I-II clinical trials, further pinpointing the need for a better knowledge of the early mechanisms of disease as well as of more effective routes of drug administration. In fact, beyond common pathological events and molecular substrates, each of these diseases preferentially affect defined subpopulations of neurons in specific neuronal circuits (selective neuronal vulnerability), leading to the typical age-related clinical profile. In this perspective, key to successful drug discovery is a robust and reproducible biological validation of potential new molecular targets together with a concomitant set up of protocols/tools for efficient and targeted brain delivery to a specific area of interest. Here we propose and discuss Focused UltraSound aided drug administration as a specific and novel technical approach to achieve optimal concentration of the drug at the target area of interest. We will focus on drug delivery to the brain through the nasal route coupled to FUS as a promising approach to achieve neuroprotection and rescue of cognitive decline in several NDs.
RESUMO
The occurrence of a sustained monomorphic ventricular tachycardias (SMVT) in patients with underlying structural heart disease (SHD) is considered related to poor prognosis. The purpose of our work was to evaluate if these patients could benefit from radiofrequency (RF) ablation, and the defibrillator (ICD) implantation could be deferred during follow-up. We reviewed consecutive patients with well-tolerated SMVT, SHD and left ventricular ejection fraction over 30%. These patients were treated by RF ablation and were discharged without ICD. The primary outcome was a composite of all-cause death and recurrence of SMVT; the secondary outcome was death from all causes. Sixty-two patients were selected. After a median follow-up of 38.8 months, the primary outcome occurred in 24 (38.7%) and the secondary in 11 (17.7%) patients. The annual mortality rate was 4.3% and no patient died from sudden death. RF ablation as a first-choice therapy seems to represent an effective and beneficial therapeutic approach.
Assuntos
Ablação por Cateter , Desfibriladores Implantáveis , Taquicardia Ventricular , Humanos , Seguimentos , Volume Sistólico , Função Ventricular Esquerda , Taquicardia Ventricular/cirurgia , Taquicardia Ventricular/etiologia , Desfibriladores Implantáveis/efeitos adversos , Arritmias Cardíacas/etiologia , Resultado do TratamentoRESUMO
Elicitation of potent and broadly neutralizing antibodies is an important goal in designing an effective human immunodeficiency virus-1 (HIV-1) vaccine. The HIV-1 gp41 inner-core trimer represents a functionally and structurally conserved target for therapeutics. Here we report the 2.0-A-resolution crystal structure of the complex between the antigen-binding fragment of D5, an HIV-1 cross-neutralizing antibody, and 5-helix, a gp41 inner-core mimetic. Both binding and neutralization depend on residues in the D5 CDR H2 loop protruding into the conserved gp41 hydrophobic pocket, as well as a large pocket in D5 surrounding core gp41 residues. Kinetic analysis of D5 mutants with perturbed D5-gp41 interactions suggests that D5 persistence at the fusion intermediate is crucial for neutralization. Thus, our data validate the gp41 N-peptide trimer fusion intermediate as a target for neutralizing antibodies and provide a template for identification of more potent and broadly neutralizing molecules.
Assuntos
Anticorpos Monoclonais/química , Proteína gp41 do Envelope de HIV/química , Proteína gp41 do Envelope de HIV/imunologia , HIV-1/imunologia , Anticorpos Monoclonais/metabolismo , Células Cultivadas , Cristalografia por Raios X , Proteína gp41 do Envelope de HIV/metabolismo , HIV-1/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Leucina/química , Modelos Moleculares , Mutação , Testes de Neutralização , Conformação Proteica , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Triptofano/químicaRESUMO
The detection of circulating microRNA (miRNA)-based biomarkers represents an innovative, non-invasive method for the early detection of cancer. However, the low concentration of miRNAs released in body fluids and the difficult identification of the tumor site have limited their clinical use as effective cancer biomarkers. To evaluate if ultrasound treatment could amplify the release of extracellular cancer biomarkers, we treated a panel of prostate cancer (PCa) cell lines with an ultrasound-based prototype and profiled the release of miRNAs in the extracellular space, with the aim of identifying novel miRNA-based biomarkers that could be used for PCa diagnosis and the monitoring of tumor evolution. We provide evidence that US-mediated sonoporation amplifies the release of miRNAs from both androgen-dependent (AD) and -independent (AI) PCa cells. We identified four PCa-related miRNAs, whose levels in LNCaP and DU145 supernatants were significantly increased following ultrasound treatment: mir-629-5p, mir-374-5p, mir-194-5p, and let-7d-5p. We further analyzed a publicly available dataset of PCa, showing that the serum expression of these novel miRNAs was upregulated in PCa patients compared to controls, thus confirming their clinical relevance. Our findings highlight the potential of using ultrasound to identify novel cell-free miRNAs released from cancer cells, with the aim of developing new biomarkers with diagnostic and predictive value.
Assuntos
Biomarcadores Tumorais/genética , MicroRNA Circulante/genética , Neoplasias da Próstata/genética , Ondas Ultrassônicas/efeitos adversos , Estudos de Casos e Controles , Linhagem Celular Tumoral , Bases de Dados Genéticas , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , MicroRNAs/genética , Células PC-3RESUMO
The number of patients affected by electrical storm has been continuously increasing in emergency departments. Patients are often affected by multiple comorbidities requiring multidisciplinary interventions to achieve a clinical stability. Careful reprogramming of cardiac devices, correction of electrolyte imbalance, knowledge of underlying heart disease and antiarrhythmic drugs in the acute phase play a crucial role. The aim of this review is to provide a comprehensive overview of pharmacological treatment, latest transcatheter ablation techniques and advanced management of patients with electrical storm.
Assuntos
Antiarrítmicos/farmacologia , Taquicardia Ventricular/terapia , Ablação por Cateter/métodos , Humanos , Administração dos Cuidados ao Paciente/métodos , Administração dos Cuidados ao Paciente/tendênciasRESUMO
Ventricular tachycardia is a major health issue in patients with structural heart disease (SHD). Implantable cardioverter defibrillator (ICD) therapy has significantly reduced the risk of sudden cardiac death (SCD) in such patients, but on the other hand, it has led to frequent ICD shocks as an emerging problem, being associated with poor quality of life, frequent hospitalizations and increased mortality. Myocardial scar plays a central role in the genesis and maintenance of re-entrant arrhythmias, as the coexistence of surviving myocardial fibres within fibrotic tissue leads to the formation of slow conduction pathways and to a dispersion of activation and refractoriness that constitutes the milieu for ventricular tachycardia circuits. Catheter ablation has repeatedly proven to be well tolerated and highly effective in treating VT and in the last two decades has benefited from continuous efforts to determine ventricular tachycardia mechanisms by integration with a wide range of invasive and noninvasive imaging techniques such as intracardiac echocardiography, cardiac magnetic resonance, multidetector computed tomography and nuclear imaging. Cardiovascular imaging has become a fundamental aid in planning and guiding catheter ablation procedures by integrating structural and electrophysiological information, enabling the ventricular tachycardia arrhythmogenic substrate to be characterized and effective ablation targets to be identified with increasing precision, and allowing the development of new ablation strategies with improved outcomes. In this review, we provide an overview of the role of cardiac imaging in patients undergoing catheter ablation of ventricular tachycardia.
Assuntos
Técnicas de Imagem Cardíaca/métodos , Ablação por Cateter/métodos , Taquicardia Ventricular , Ablação por Cateter/tendências , Humanos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/cirurgiaRESUMO
The molecular determinants necessary and sufficient for recognition of its specific DNA target are contained in the C-terminal domain (H-NSctd) of nucleoid-associated protein H-NS. H-NSctd protects from DNaseI cleavage a few short DNA segments of the H-NS-sensitive hns promoter whose sequences closely match the recently identified H-NS consensus motif (tCG(t/a)T(a/t)AATT) and, alone or fused to the protein oligomerization domain of phage lambda CI repressor, inhibits transcription from the hns promoter in vitro and in vivo. The importance of H-NS oligomerization is indicated by the fact that with an extended hns promoter construct (400 bp), which allows protein oligomerization, DNA binding and transcriptional repression are highly and almost equally efficient with native H-NS and H-NSctd::lambdaCI and much less effective with the monomeric H-NSctd. With a shorter (110 bp) construct, which does not sustain extensive protein oligomerization, transcriptional repression is less effective, but native H-NS, H-NSctd::lambdaCI, and monomeric H-NSctd have comparable activity on this construct. The specific H-NS-DNA interaction was investigated by NMR spectroscopy using monomeric H-NSctd and short DNA duplexes encompassing the H-NS target sequence of hns (TCCTTACATT) with the best fit (8 of 10 residues) to the H-NS-binding motif. H-NSctd binds specifically and with high affinity to the chosen duplexes via an overall electropositive surface involving four residues (Thr(109), Arg(113), Thr(114), and Ala(116)) belonging to the same protein loop and Glu(101). The DNA target is recognized by virtue of its sequence and of a TpA step that confers a structural irregularity to the B-DNA duplex.
Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Motivos de Aminoácidos , Sequência de Bases , Sítios de Ligação , Clonagem Molecular , Escherichia coli/genética , Espectroscopia de Ressonância Magnética , Regiões Promotoras Genéticas , Multimerização Proteica , Proteínas RepressorasRESUMO
AIMS: International and national consensus guidelines define appropriate indications for implantable cardioverter-defibrillators (ICDs), but the variability in implant rates in 'real world' clinical practice is still unknown. METHODS AND RESULTS: In Emilia-Romagna, an Italian region with around 4.3 million inhabitants, a web-based registry was instituted to collect data for all ICDs implanted. Between January 2006 and December 2008, data from all consecutive patients resident in this region who underwent first implant of an ICD or a biventricular ICD were collected and standardized, considering each regional area (i.e. each of the nine provinces). The overall number of implanted ICDs had an increase in years 2007 and 2008, with a relative increase in comparison to 2006, by 14 and 48% respectively, reaching an average value of 16.2 per 10,000 inhabitants in 2008. Most of the increase was due to a rise in ICDs for primary prevention. The ratio between the implant rates of the provinces with the highest and the lowest implant rates, respectively, was around 2 in 2008. CONCLUSION: Implant rates for ICDs, considering both primary and secondary prevention of sudden death, show up to two-fold variations even in a geographical region where the general level of health care is advanced and well appreciated by the population. The lack of a common strategy for sudden death prevention, approved by both physicians and institutional regional authorities, together with some degree of variability in translating guidelines into clinical practice, were identified as the main factors explaining the heterogeneity in ICD implant rates.
Assuntos
Morte Súbita Cardíaca/prevenção & controle , Desfibriladores Implantáveis/estatística & dados numéricos , Humanos , Itália , Sistema de RegistrosRESUMO
The human telomerase reverse transcriptase (hTERT) is an attractive target for human cancer vaccination because its expression is reactivated in most human tumors. We have evaluated the ability of DNA electroporation (DNA-EP) and adenovirus serotype 6 (Ad6) to induce immune responses against hTERT in nonhuman primates (NHPs) (Macaca mulatta). Vaccination was effective in all treated animals, and the adaptive immune response remained detectable and long lasting without side effects. To further enhance the efficacy of the hTERT vaccine, we evaluated the combination of hTERT vaccine and a novel TLR9 agonist, referred to as immunomodulatory oligonucleotide (IMO). Monkeys were dosed weekly with IMO concurrently with the vaccine regimen and showed increases in cytokine secretion and activation of natural killer (NK) cells compared with the group that received vaccine alone. Using a peptide array, a specific profile of B-cell reactive epitopes was identified when hTERT vaccine was combined with IMO. The combination of IMO with hTERT genetic vaccine did not impact vaccine-induced TERT-specific cell-mediated immunity. Our results show that appropriate combination of a DNA-EP/Ad6-based cancer vaccine against hTERT with IMO induces multiple effects on innate and adaptive immune responses in NHPs.
Assuntos
Imunidade Inata/efeitos dos fármacos , Fatores Imunológicos/farmacologia , Telomerase/imunologia , Receptor Toll-Like 9/agonistas , Adenoviridae/genética , Animais , Eletroporação , Epitopos de Linfócito B/imunologia , Imunidade Celular/imunologia , Imunidade Inata/genética , Interferon-alfa/metabolismo , Interleucina-10/metabolismo , Interleucina-12/metabolismo , Interleucina-6/metabolismo , Macaca mulatta , Telomerase/genéticaRESUMO
Phosphatase of Regenerating Liver-3 (PRL-3) is a small protein tyrosine phosphatase considered an appealing therapeutic cancer target due to its involvement in metastatic progression. However, despite its importance, the direct molecular targets of PRL-3 action are not yet known. Here we report the identification of Ezrin as a specific and direct cellular substrate of PRL-3. In HCT116 colon cancer cell line, Ezrin was identified among the cellular proteins whose phosphorylation level decreased upon ectopic over-expression of wtPRL-3 but not of catalytically inactive PRL-3 mutants. Although PRL-3 over-expression in HCT116 cells appeared to affect Ezrin phosphorylation status at both tyrosine residues and Thr567, suppression of the endogenous protein by RNA interference pointed to Ezrin-Thr567 as the residue primarily affected by PRL-3 action. In vitro dephosphorylation assays suggested Ezrin-Thr567 as a direct substrate of PRL-3 also proving this enzyme as belonging to the dual specificity phosphatase family. Furthermore, the same effect on levels of pThr567, but not on pTyr residues, was observed in endothelial cells pointing to Ezrin-pThr567 dephosphorylation as a mean through which PRL-3 exerts its function in promoting tumor progression as well as in the establishment of the new vasculature needed for tumor survival and expansion.
Assuntos
Proteínas do Citoesqueleto/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Catálise/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/enzimologia , Células HCT116 , Humanos , Proteínas Mutantes/metabolismo , Fosforilação/efeitos dos fármacos , Fosfotreonina/metabolismo , Fosfotirosina/metabolismo , Interferência de RNA , Especificidade por Substrato/efeitos dos fármacos , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
The Phosphatase of Regenerating Liver-3 (PRL-3) is a cysteine-based phosphatase (CBP) that is highly over-expressed in liver metastasis in colorectal cancer and suspected to be involved in the progression from tumor to metastasis. During substrate-specificity studies based on the screening of PRL-3 phosphatase activity on several phosphorylated synthetic peptides, we observed a decrease in activity depending on sample aging and storage conditions. By liquid chromatography combined with selective alkylation and mass spectrometry, we found two main PRL-3 inactivation pathways: a disulfide bond formation between the catalytic C104 and C49, blocking the enzyme in an inactive oxidized form, or the conversion of the catalytic C104 into glycine. We also found that the disulfide formation and the cysteine into glycine conversion are catalyzed by cations present in the sample after protein purification through a nickel column. By adding a cation chelator such as EDTA and de-oxygenating the sample with argon, PRL-3 phosphatase activity was preserved. These findings suggest that PRL-3, like other CBPs, is sensitive to inactivation by catalytic cysteine oxidation and this has implications for future studies of its activity and specificity.