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1.
Lab Med ; 51(6): 574-578, 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-32195537

RESUMO

OBJECTIVE: This study aimed at confirming the alteration of circulating anti-p16 immunoglobulin G (IgG) levels in hepatocellular carcinoma (HCC). METHODS: An in-house-developed enzyme-linked immunosorbent assay was used for determining plasma IgG antibodies against p16-derived antigens in 122 HCC patients and 134 healthy controls. RESULTS: Plasma anti-p16 IgG levels were significantly higher in HCC patients than in the controls (Z = 3.51, P = 0.0004), with no difference between males and females. A trend of increasing plasma anti-p16 IgG levels was associated with increasing HCC stage, with group 3 patients having the highest anti-p16 IgG levels (Z = 3.38, P = 0.0008). Group 3 exhibited the best sensitivity (19.6%) and specificity (95%) for plasma anti-p16 IgG detection, with an area under the receiver operating characteristic curve of 0.659 (95% confidence interval, 0.564-0.754). CONCLUSION: Circulating IgG antibody to p16 protein might be a useful biomarker for HCC prognosis assessment rather than for early malignancy diagnosis.


Assuntos
Autoanticorpos/sangue , Carcinoma Hepatocelular/sangue , Inibidor p16 de Quinase Dependente de Ciclina/imunologia , Neoplasias Hepáticas/sangue , Peptídeos , Adulto , Idoso , Autoanticorpos/imunologia , Biomarcadores Tumorais , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/imunologia , Estudos de Casos e Controles , Inibidor p16 de Quinase Dependente de Ciclina/química , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/imunologia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Peptídeos/imunologia , Prognóstico , Curva ROC
2.
Redox Biol ; 28: 101316, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539802

RESUMO

The tumor suppressor p16INK4A induces cell cycle arrest and senescence in response to oncogenic transformation and is therefore frequently lost in cancer. p16INK4A is also known to accumulate under conditions of oxidative stress. Thus, we hypothesized it could potentially be regulated by reversible oxidation of cysteines (redox signaling). Here we report that oxidation of the single cysteine in p16INK4A in human cells occurs under relatively mild oxidizing conditions and leads to disulfide-dependent dimerization. p16INK4A is an all α-helical protein, but we find that upon cysteine-dependent dimerization, p16INK4A undergoes a dramatic structural rearrangement and forms aggregates that have the typical features of amyloid fibrils, including binding of diagnostic dyes, presence of cross-ß sheet structure, and typical dimensions found in electron microscopy. p16INK4A amyloid formation abolishes its function as a Cyclin Dependent Kinase 4/6 inhibitor. Collectively, these observations mechanistically link the cellular redox state to the inactivation of p16INK4A through the formation of amyloid fibrils.


Assuntos
Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Cisteína/química , Amiloide/química , Ciclo Celular , Senescência Celular , Inibidor p16 de Quinase Dependente de Ciclina/genética , Células HEK293 , Humanos , Modelos Moleculares , Oxirredução , Multimerização Proteica , Estrutura Secundária de Proteína
3.
J Phys Chem Lett ; 10(15): 4382-4400, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31304749

RESUMO

It has been demonstrated that MMP13 enzyme is related to most cancer cell tumors. The world's largest traditional Chinese medicine database was applied to screen for structure-based drug design and ligand-based drug design. To predict drug activity, machine learning models (Random Forest (RF), AdaBoost Regressor (ABR), Gradient Boosting Regressor (GBR)), and Deep Learning models were utilized to validate the Docking results, and we obtained an R2 of 0.922 on the training set and 0.804 on the test set in the RF algorithm. For the Deep Learning algorithm, R2 of the training set is 0.90, and R2 of the test set is 0.810. However, these TCM compounds fly away during the molecular dynamics (MD) simulation. We seek another method: peptide design. All peptide database were screened by the Docking process. Modification peptides were optimized the interaction modes, and the affinities were assessed with ZDOCK protocol and Refine Docked protein protocol. The 300 ns MD simulation evaluated the stability of receptor-peptide complexes. The double-site effect appeared on S2, a designed peptide based on a known inhibitor, when complexed with BCL2. S3, a designed peptide referred from endogenous inhibitor P16, competed against cyclin when binding with CDK6. The MDM2 inhibitors S5 and S6 were derived from the P53 structure and stable binding with MDM2. A flexible region of peptides S5 and S6 may enhance the binding ability by changing its own conformation, which was unforeseen. These peptides (S2, S3, S5, and S6) are potentially interesting to treat cancer; however, these findings need to be affirmed by biological testing, which will be conducted in the near future.


Assuntos
Antineoplásicos/química , Aprendizado Profundo , Aprendizado de Máquina , Modelos Moleculares , Peptídeos/química , Proteínas/química , Algoritmos , Sítios de Ligação , Quinase 6 Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/química , Bases de Dados de Produtos Farmacêuticos , Bases de Dados de Proteínas , Desenho de Fármacos , Ligantes , Metaloproteinase 13 da Matriz/química , Mutação , Proteínas Proto-Oncogênicas c-bcl-2/química , Proteínas Proto-Oncogênicas c-mdm2/química , Proteína Supressora de Tumor p53/química , Proteína Supressora de Tumor p53/genética
4.
Mol Cancer Ther ; 18(4): 771-779, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30837298

RESUMO

The interaction of a drug with its target is critical to achieve drug efficacy. In cases where cellular environment influences target engagement, differences between individuals and cell types present a challenge for a priori prediction of drug efficacy. As such, characterization of environments conducive to achieving the desired pharmacologic outcome is warranted. We recently reported that the clinical CDK4/6 inhibitor palbociclib displays cell type-specific target engagement: Palbociclib engaged CDK4 in cells biologically sensitive to the drug, but not in biologically insensitive cells. Here, we report a molecular explanation for this phenomenon. Palbociclib target engagement is determined by the interaction of CDK4 with CDKN2A, a physiologically relevant protein inhibitor of CDK4. Because both the drug and CDKN2A prevent CDK4 kinase activity, discrimination between these modes of inhibition is not possible by traditional kinase assays. Here, we describe a chemo-proteomics approach that demonstrates high CDK4 target engagement by palbociclib in cells without functional CDKN2A and attenuated target engagement when CDKN2A (or related CDKN2/INK4 family proteins) is abundant. Analysis of biological sensitivity in engineered isogenic cells with low or absent CDKN2A and of a panel of previously characterized cell lines indicates that high levels of CDKN2A predict insensitivity to palbociclib, whereas low levels do not correlate with sensitivity. Therefore, high CDKN2A may provide a useful biomarker to exclude patients from CDK4/6 inhibitor therapy. This work exemplifies modulation of kinase target engagement by endogenous proteinaceous regulators and highlights the importance of cellular context in predicting inhibitor efficacy.


Assuntos
Quinase 4 Dependente de Ciclina/antagonistas & inibidores , Quinase 4 Dependente de Ciclina/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Biomarcadores Tumorais/metabolismo , Proliferação de Células/efeitos dos fármacos , Quinase 4 Dependente de Ciclina/química , Quinase 6 Dependente de Ciclina/antagonistas & inibidores , Quinase 6 Dependente de Ciclina/química , Inibidor de Quinase Dependente de Ciclina p15/química , Inibidor de Quinase Dependente de Ciclina p15/genética , Inibidor de Quinase Dependente de Ciclina p15/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/genética , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Técnicas de Inativação de Genes , Humanos , Células MCF-7 , Mutação de Sentido Incorreto , Proteínas do Tecido Nervoso/genética , Piperazinas/química , Ligação Proteica , Inibidores de Proteínas Quinases/química , Piridinas/química , Transfecção
5.
Dis Model Mech ; 12(4)2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30910991

RESUMO

Pancreatic cancer is one of the most lethal common cancers. The cell of origin of pancreatic ductal adenocarcinoma (PDAC) has been controversial, and recent evidence suggested acinar cells as the most probable candidate. However, the genetic alterations driving the transformation of pancreatic acinar cells in fully mature animals remain to be deciphered. In this study, lentivirus was used as a tool to introduce genetic engineering in tree shrew pancreatic acinar cells to explore the driver mutation essential for malignant transformation, establishing a novel tree shrew PDAC model, because we found that lentivirus could selectively infect acinar cells in tree shrew pancreas. Combination of oncogenic KRASG12D expression and inactivation of tumor suppressor genes Tp53, Cdkn2a and Cdkn2b could induce pancreatic cancer with full penetrance. Silencing of Cdkn2b is indispensable for Rb1 phosphorylation and tumor induction. Tree shrew PDAC possesses the main histological and molecular features of human PDAC. The gene expression profile of tree shrew PDAC was more similar to human disease than a mouse model. In conclusion, we established a novel pancreatic cancer model in tree shrew and identified driver mutations indispensable for PDAC induction from acinar cells in mature adults, demonstrating the essential roles of Cdkn2b in the induction of PDAC originating from adult acinar cells. Tree shrew could thus provide a better choice than mouse for a PDAC model derived from acinar cells in fully mature animals.


Assuntos
Células Acinares/patologia , Transformação Celular Neoplásica/patologia , Neoplasias Pancreáticas/patologia , Tupaia/fisiologia , Células Acinares/virologia , Sequência de Aminoácidos , Animais , Carcinogênese/patologia , Carcinoma Ductal Pancreático/patologia , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Modelos Animais de Doenças , Lentivirus/metabolismo , Masculino , Metaplasia , Camundongos , Primatas , Proteína do Retinoblastoma/metabolismo , Transdução de Sinais
6.
J Phys Chem B ; 122(9): 2525-2535, 2018 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-29425042

RESUMO

The development of computational efficient models is essential to obtain a detailed characterization of the mechanisms underlying the folding of proteins and the formation of amyloid fibrils. Structure-based computational models (Go-model) with Cα or all-atom resolutions have been able to successfully delineate the mechanisms of folding of several globular proteins and offer an interesting alternative to computationally intensive simulations with explicit solvent description. Here, we explore the limits of Go-model predictions by analyzing the folding of the nonglobular repeat domain proteins Notch Ankyrin and p16INK4 and the formation of human islet amyloid polypeptide (hIAPP) fibrils. Folding trajectories of the repeat domain proteins revealed that an all-atom resolution is required to capture the folding pathways and cooperativity reported in experimental studies. The all-atom Go-model was also successful in predicting the free-energy landscape of hIAPP fibrillation, suggesting a "dock and lock" mechanism of fibril elongation. We finally explored how mutations can affect the co-assembly of hIAPP fibrils by simulating a heterogeneous system composed of wild-type and mutated hIAPP peptides. Overall, this study shows that all-atom Go-model-based simulations have the potential of discerning the effects of mutations and post-translational modifications in protein folding and association and may help in resolving the dichotomy between experimental and theoretical studies on protein folding and amyloid fibrillation.


Assuntos
Inibidor p16 de Quinase Dependente de Ciclina/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Simulação de Dinâmica Molecular , Proteínas de Neoplasias/química , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Conformação Proteica , Dobramento de Proteína
7.
BMC Cancer ; 16: 571, 2016 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-27485348

RESUMO

BACKGROUND: Cell-penetrating peptides (CPPs) are a research hotspot due to their noninvasive delivery ability. Among the identified CPPs, the TAT and R8 peptides have been preferentially applied to transduction into different cells. However, this process is nonselective among various cells. Recent research suggested that CPP2 could selectively penetrate human colorectal cancer (CRC) cells. METHODS: Using in vitro experiments, the mean fluorescence intensity of fluorescein isothiocyanate-labeled CPPs (CPPs-FITC) incubated with different cell lines was compared to corroborate the colon tumor targeting ability of CPP2. The targeting ability of CPP2 was determined in the same way in tumor-bearing mice. We synthesized antitumor peptides by fusing CPP2 to the minimal inhibitory sequence of p16 (p16MIS), which had the ability to restore the function of lost p16, the expression of which was absent in tumor cell lines of various origins. The antitumor effect of the combined peptide was tested in both CRC cell lines and tumor-bearing mice. RESULTS: In each CRC cell line, the mean fluorescence intensity of CPP2-FITC was higher than that of the TAT-FITC (p < 0.001) and R8-FITC (p < 0.001) groups. CPP2-p16MIS, the targeting carrier, showed a higher antitumor response in the in vitro cell research. CPP2-p16MIS showed a prolonged mean lifespan of tumor-bearing mice, further characterizing its role in specific tumor-targeting ability in vivo. Survival analysis showed that the mice treated with CPP2-p16MIS had significantly longer survival than the mice treated with phosphate-buffered saline (p < 0.05) or those treated with control peptides, including the CPP2 (p < 0.05) and p16MIS (p < 0.05) groups. CONCLUSION: CPP2 could more selectively penetrate CRC cells than TAT or R8 as well as effectively deliver the p16MIS to the tumor.


Assuntos
Peptídeos Penetradores de Células/farmacologia , Neoplasias Colorretais/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Terapia de Alvo Molecular/métodos , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Peptídeos Penetradores de Células/síntese química , Neoplasias Colorretais/terapia , Inibidor p16 de Quinase Dependente de Ciclina/química , Células HCT116 , Humanos , Camundongos , Resultado do Tratamento , Ensaios Antitumorais Modelo de Xenoenxerto
8.
Nat Commun ; 6: 6471, 2015 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-25753524

RESUMO

Despite recent advances in the cure rate of acute lymphoblastic leukaemia (ALL), the prognosis for patients with relapsed ALL remains poor. Here we identify FOXM1 as a candidate responsible for an aggressive clinical course. We show that FOXM1 levels peak at the pre-B-cell receptor checkpoint but are dispensable for normal B-cell development. Compared with normal B-cell populations, FOXM1 levels are 2- to 60-fold higher in ALL cells and are predictive of poor outcome in ALL patients. FOXM1 is negatively regulated by FOXO3A, supports cell survival, drug resistance, colony formation and proliferation in vitro, and promotes leukemogenesis in vivo. Two complementary approaches of pharmacological FOXM1 inhibition-(i) FOXM1 transcriptional inactivation using the thiazole antibiotic thiostrepton and (ii) an FOXM1 inhibiting ARF-derived peptide-recapitulate the findings of genetic FOXM1 deletion. Taken together, our data identify FOXM1 as a novel therapeutic target, and demonstrate feasibility of FOXM1 inhibition in ALL.


Assuntos
Antineoplásicos/farmacologia , Fatores de Transcrição Forkhead/antagonistas & inibidores , Regulação Leucêmica da Expressão Gênica , Peptídeos/síntese química , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Tioestreptona/farmacologia , Adulto , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/metabolismo , Linfócitos B/patologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Criança , Ensaios Clínicos como Assunto , Inibidor p16 de Quinase Dependente de Ciclina/química , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Forkhead Box M1 , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Humanos , Camundongos , Peptídeos/farmacologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Transdução de Sinais , Análise de Sobrevida , Ensaios Antitumorais Modelo de Xenoenxerto
9.
J Pept Sci ; 21(4): 265-73, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25754556

RESUMO

Protein p(16INK4a) (p16) is a well-known biomarker for diagnosis of human papillomavirus (HPV) related cancers. In this work, we identify novel p16 binding peptides by using phage display selection method. A random heptamer phage display library was screened on purified recombinant p16 protein-coated plates to elute only the bound phages from p16 surfaces. Binding affinity of the bound phages was compared with each other by enzyme-linked immunosorbent assay (ELISA), fluorescence imaging technique, and bioinformatic computations. Binding specificity and binding selectivity of the best candidate phage-displayed p16 binding peptide were evaluated by peptide blocking experiment in competition with p16 monoclonal antibody and fluorescence imaging technique, respectively. Five candidate phage-displayed peptides were isolated from the phage display selection method. All candidate p16 binding phages show better binding affinity than wild-type phage in ELISA test, but only three of them can discriminate p16-overexpressing cancer cell, CaSki, from normal uterine fibroblast cell, HUF, with relative fluorescence intensities from 2.6 to 4.2-fold greater than those of wild-type phage. Bioinformatic results indicate that peptide 'Ser-His-Ser-Leu-Leu-Ser-Ser' binds to p16 molecule with the best binding score and does not interfere with the common protein functions of p16. Peptide blocking experiment shows that the phage-displayed peptide 'Ser-His-Ser-Leu-Leu-Ser-Ser' can conceal p16 from monoclonal antibody interaction. This phage clone also selectively interacts with the p16 positive cell lines, and thus, it can be applied for p16-overexpressing cell detection.


Assuntos
Inibidor p16 de Quinase Dependente de Ciclina/química , Neoplasias/diagnóstico , Biblioteca de Peptídeos , Linhagem Celular , Humanos , Simulação de Acoplamento Molecular , Neoplasias/metabolismo , Ligação Proteica
10.
Chem Biol ; 22(2): 161-8, 2015 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-25660273

RESUMO

Chromobox homolog 7 (CBX7) plays an important role in gene transcription in a wide array of cellular processes, ranging from stem cell self-renewal and differentiation to tumor progression. CBX7 functions through its N-terminal chromodomain (ChD), which recognizes trimethylated lysine 27 of histone 3 (H3K27me3), a conserved epigenetic mark that signifies gene transcriptional repression. In this study, we report the discovery of small molecules that inhibit CBX7ChD binding to H3K27me3. Our crystal structures reveal the binding modes of these molecules that compete against H3K27me3 binding through interactions with key residues in the methyl-lysine binding pocket of CBX7ChD. We further show that a lead compound, MS37452, derepresses transcription of Polycomb repressive complex target gene p16/CDKN2A by displacing CBX7 binding to the INK4A/ARF locus in prostate cancer cells. These small molecules have the potential to be developed into high-potency chemical modulators that target CBX7 functions in gene transcription in different disease pathways.


Assuntos
Complexo Repressor Polycomb 1/química , Bibliotecas de Moléculas Pequenas/química , Sítios de Ligação , Linhagem Celular Tumoral , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Fluoresceína-5-Isotiocianato/química , Histonas/química , Histonas/metabolismo , Humanos , Lisina/química , Lisina/metabolismo , Metilação , Complexo Repressor Polycomb 1/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Bibliotecas de Moléculas Pequenas/metabolismo , Eletricidade Estática , Suramina/química , Suramina/metabolismo
11.
J Biol Chem ; 288(49): 35511-25, 2013 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-24163379

RESUMO

p16(INK4a) is a tumor suppressor protein involved in several stress-related cellular responses, including apoptosis. Recent lines of evidence indicate that p16(INK4a) is also a modulator of gene expression. However, the molecular mechanisms underlying this novel function are still obscure. Here, we present clear evidence that p16(INK4a) modulates the levels of various microRNAs, with marked positive effect on miR-141 and miR-146b-5p. This effect is mediated through the formation of the p16-CDK4-Sp1 heterocomplex, which binds to Sp1 consensus-binding motifs present in the promoters of miR-141 and miR-146b-5p, and it enables their transcription. In addition, we have shown that p16(INK4a) interacts with Sp1 through the fourth ankyrin repeat, which is crucial for Sp1 binding to the miR-141 and miR-146b-5p promoters and their transcriptional activation. The physiological importance of this association was revealed by the inability of cancer-related p16(INK4a) mutants to interact with Sp1. Moreover, we have shown p16-CDK4-Sp1-dependent up-regulation of miR-141 and miR-146b-5p following UV light-induced DNA damage and the role of these two microRNAs in mediating p16-related induction of apoptosis in response to this genotoxic stress. Together, these results indicate that p16(INK4a) associates with CDK4 not only to inhibit the cell cycle but also to enable the transcription of two important onco-microRNAs, which act as downstream effectors.


Assuntos
Quinase 4 Dependente de Ciclina/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Fator de Transcrição Sp1/metabolismo , Sequência de Bases , Ciclo Celular , Linhagem Celular , Quinase 4 Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/química , Dano ao DNA , Humanos , Dados de Sequência Molecular , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Regiões Promotoras Genéticas , Ligação Proteica , Estabilidade de RNA , Fator de Transcrição Sp1/química , Ativação Transcricional/efeitos da radiação , Raios Ultravioleta/efeitos adversos
12.
J Chem Inf Model ; 53(10): 2634-47, 2013 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-24047445

RESUMO

A software tool and workflow based on distance geometry is presented that can be used to search for local similarity in substructures in a comprehensive database of experimentally derived macromolecular structure. The method does not rely on fold annotation, specific secondary structure assignments, or sequence homology and may be used to locate compound substructures of multiple segments spanning different macromolecules that share a queried backbone geometry. This generalized substructure searching capability is intended to allow users to play an active part in exploring the role specific substructures play in larger protein domains, quaternary assemblies of proteins, and macromolecular complexes of proteins and polynucleotides. The user may select any portion or portions of an existing structure or complex to serve as a template for searching, and other structures that share the same structural features are identified, retrieved and overlaid to emphasize substructural likeness. Matching structures may be compared using a variety of integrated tools including molecular graphics for structure visualization and matching substructure sequence logos. A number of examples are provided that illustrate how generalized substructure searching may be used to understand both the similarity, and individuality of specific macromolecular structures. Web-based access to our substructure searching services is freely available at https://drugsite.msi.umn.edu.


Assuntos
Algoritmos , Anquirinas/química , Inibidor p16 de Quinase Dependente de Ciclina/química , DNA/química , Polinucleotídeos/química , Software , Sequência de Aminoácidos , Bases de Dados de Compostos Químicos , Bases de Dados de Proteínas , Humanos , Internet , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Homologia Estrutural de Proteína
13.
Int J Surg ; 11(7): 549-53, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23721661

RESUMO

CDKN2A promoter hypermethylation has been widely related to many cancers. In astrocytomas, although CDKN2A (p16(INK4A) protein) is often inactivated, there are still some controversial issues regarding the mechanism by which this alteration occurs. Thus, we analyzed a series of astrocytomas to assess the association between CDKN2A expression and methylation of grade I-IV tumors (WHO) and clinicopathological parameters. DNA extracted from formalin-fixed paraffin-embedded material of 93 astrocytic tumors was available for CDKN2A promoter methylation analysis and p16(INK4A) expression by methylation-specific PCR and immunohistochemistry, respectively. A strong negative correlation between nuclear and cytoplasmic immunostaining and CDKN2A promoter methylation was found. Additionally, a significant negative correlation between CDKN2A promoter methylation and age was observed; also, female patients had statistically more CDKN2A methylated promoters (p = 0.036) than men. In conclusion, CDKN2A inactivation by promoter methylation is a frequent event in astrocytomas and it is related to the age and sex of patients.


Assuntos
Astrocitoma/genética , Neoplasias Encefálicas/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Metilação de DNA , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Astrocitoma/química , Astrocitoma/metabolismo , Neoplasias Encefálicas/química , Neoplasias Encefálicas/metabolismo , Distribuição de Qui-Quadrado , Criança , Pré-Escolar , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Regiões Promotoras Genéticas , Estatísticas não Paramétricas
14.
Mol Cancer Ther ; 12(5): 759-67, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23427295

RESUMO

The forkhead box transcription factor FOXM1 is considered to be a promising target for cancer therapy. However, the significance of FOXM1 in tumors harboring mutation in p53, which is very common, is unclear. In this study, we investigated the efficacy of FoxM1 targeting in spontaneous p53-null tumors using genetic ablation as well as using a peptide inhibitor of FOXM1. We show that conditional deletion of FoxM1 inhibits growth of the p53-null thymic lymphoma and sarcoma cells. In addition, deletion of FoxM1 induces apoptotic cell death of the p53-null tumors, accompanied by reduced expression of the FOXM1 target genes survivin and Bmi1. An ARF-derived peptide that inhibits the activity of FOXM1, by targeting it to the nucleolus, also induces apoptosis in the p53-null sarcoma and lymphoma, leading to a strong inhibition of their metastatic colonization. Together, our observations suggest that FOXM1 is critical for survival and growth of the p53-null lymphoma and sarcoma and provide proof-of-principle that FOXM1 is an effective therapeutic target for sarcoma and lymphoma carrying loss of function mutation in p53.


Assuntos
Fatores de Transcrição Forkhead/antagonistas & inibidores , Linfoma/genética , Linfoma/metabolismo , Sarcoma/genética , Sarcoma/metabolismo , Proteína Supressora de Tumor p53/genética , Aloenxertos , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Inibidor p16 de Quinase Dependente de Ciclina/química , Modelos Animais de Doenças , Proteína Forkhead Box M1 , Fatores de Transcrição Forkhead/genética , Regulação Neoplásica da Expressão Gênica , Proteínas Inibidoras de Apoptose/genética , Proteínas Inibidoras de Apoptose/metabolismo , Camundongos , Camundongos Knockout , Peptídeos/farmacologia , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Survivina , Neoplasias do Timo/genética , Neoplasias do Timo/metabolismo
15.
Theor Biol Med Model ; 10: 1, 2013 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-23276293

RESUMO

BACKGROUND: Lung cancer is the major cause of mortality worldwide. Major signalling pathways that could play significant role in lung cancer therapy include (1) Growth promoting pathways (Epidermal Growth Factor Receptor/Ras/ PhosphatidylInositol 3-Kinase) (2) Growth inhibitory pathways (p53/Rb/P14ARF, STK11) (3) Apoptotic pathways (Bcl-2/Bax/Fas/FasL). Insilico strategy was implemented to solve the mystery behind selected lung cancer pathway by applying comparative modeling and molecular docking studies. RESULTS: YASARA [v 12.4.1] was utilized to predict structural models of P16-INK4 and RB1 genes using template 4ELJ-A and 1MX6-B respectively. WHAT CHECK evaluation tool demonstrated overall quality of predicted P16-INK4 and RB1 with Z-score of -0.132 and -0.007 respectively which showed a strong indication of reliable structure prediction. Protein-protein interactions were explored by utilizing STRING server, illustrated that CDK4 and E2F1 showed strong interaction with P16-INK4 and RB1 based on confidence score of 0.999 and 0.999 respectively. In order to facilitate a comprehensive understanding of the complex interactions between candidate genes with their functional interactors, GRAMM-X server was used. Protein-protein docking investigation of P16-INK4 revealed four ionic bonds illustrating Arg47, Arg80,Cys72 and Met1 residues as actively participating in interactions with CDK4 while docking results of RB1 showed four hydrogen bonds involving Glu864, Ser567, Asp36 and Arg861 residues which interact strongly with its respective functional interactor E2F1. CONCLUSION: This research may provide a basis for understanding biological insights of P16-INK4 and RB1 proteins which will be helpful in future to design a suitable drug to inhibit the disease pathogenesis as we have determined the interacting amino acids which can be targeted in order to design a ligand in-vitro to propose a drug for clinical trials. Protein -protein docking of candidate genes and their important interacting residues likely to be provide a gateway for developing computer aided drug designing.


Assuntos
Ciclina D1/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Fator de Transcrição E2F1/metabolismo , Neoplasias Pulmonares/genética , Simulação de Acoplamento Molecular , Proteína do Retinoblastoma/genética , Transdução de Sinais/genética , Ciclina D1/química , Ciclina D1/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Humanos , Neoplasias Pulmonares/metabolismo , Ligação Proteica/genética , Proteína do Retinoblastoma/química , Proteína do Retinoblastoma/metabolismo
16.
J Mol Model ; 19(4): 1507-14, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23263360

RESUMO

Survivin, the smallest inhibitor of apoptosis protein (IAP), is a valid target for cancer research. It mediates both the apoptosis pathway and the cell cycle and has been proposed to form a complex with the cyclin-dependent kinase protein CDK4. The resulting complex transports CDK4 from the cytosol to the nucleus, where CDK4 participates in cell division. Survivin has been recognized as a node protein that interacts with several partners; disruption of the formed complexes can lead to new anticancer compounds. We propose a rational model of the survivin/CDK4 complex that fulfills the experimental evidence and that can be used for structure-based design of inhibitors modifying its interface recognition. In particular, the suggested complex involves the alpha helical domain of survivin and resembles the mode of binding of survivin in the survivin/borealin X-ray structure. The proposed model has been obtained by combining protein-protein docking, fractal-based shape complementarity, electrostatics studies and extensive molecular dynamics simulations.


Assuntos
Quinase 4 Dependente de Ciclina/química , Proteínas Inibidoras de Apoptose/química , Proteínas de Neoplasias/química , Sítios de Ligação , Proteínas de Ciclo Celular/química , Cristalografia por Raios X , Quinase 6 Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/química , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Eletricidade Estática , Homologia Estrutural de Proteína , Survivina
17.
Oncogene ; 32(28): 3350-8, 2013 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-22890319

RESUMO

Nucleophosmin (NPM), a ubiquitously and abundantly expressed protein, occurs in the nucleolus, shuttling between the nucleoplasm and cytoplasm. The NPM gene is mutated in almost 30% of human acute myeloid leukemia cells. NPM interacts with p53 and p19(Arf), directs localization of p19(Arf) in the nucleolus and protects the latter from degradation. Hepatocyte odd protein shuttling (HOPS) is also a ubiquitously expressed protein that moves between the nucleus and cytoplasm. Within the nucleus of resting cells, HOPS overexpression causes cell cycle arrest in G0/G1. HOPS knockdown causes centrosome hyperamplification leading to multinucleated cells and the formation of micronuclei. We demonstrate a direct interaction of HOPS with NPM and p19(Arf), resulting in a functionally active trimeric complex. NPM appeared to regulate HOPS half-life, which, in turn, stabilized p19(Arf) and controlled its localization in the nucleolus. These findings suggest that HOPS acts as a functional bridge in the interaction between NPM and p19(Arf), providing new mechanistic insight into how NPM and p19(Arf) will oppose tumor cell proliferation.


Assuntos
Proteínas de Transporte/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Proteínas Nucleares/metabolismo , Animais , Proteínas de Transporte/química , Proteínas de Transporte/genética , Ciclo Celular , Linhagem Celular , Inibidor p16 de Quinase Dependente de Ciclina/química , Técnicas de Inativação de Genes , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana , Camundongos , Proteínas Nucleares/química , Proteínas Nucleares/deficiência , Proteínas Nucleares/genética , Nucleofosmina , Multimerização Proteica , Estabilidade Proteica , Estrutura Quaternária de Proteína , Transporte Proteico
18.
J Invest Dermatol ; 133(4): 1043-51, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23190892

RESUMO

Familial melanoma is associated with point mutations in the cyclin-dependent kinase (CDK) inhibitor p16(INK4A) (p16). We recently reported that p16 regulates intracellular oxidative stress in a cell cycle-independent manner. Here we constructed 12 different familial melanoma-associated point mutants spanning the p16 coding region and analyzed their capacity to regulate cell cycle phase and suppress reactive oxygen species (ROS). Compared with wild-type p16, which fully restored both functions in p16-deficient fibroblasts, various p16 mutants differed in their capacity to normalize ROS and cell cycle profiles. Although some mutations did not impair either function, others impaired both. Interestingly, several mutations impaired cell cycle (R24Q, R99P, and V126D) or oxidative functions (A36P, A57V, and P114S) selectively, indicating that these two functions of p16 can be uncoupled. Similar activities were confirmed with selected mutants in human melanoma cells. Many mutations impairing both cell cycle and oxidative functions, or only cell cycle function, localize to the third ankyrin repeat of the p16 molecule. Alternatively, most mutations impairing oxidative but not cell cycle function, or those not impairing either function, lie outside this region. These results demonstrate that particular familial melanoma-associated mutations in p16 can selectively compromise these two independent tumor-suppressor functions, which may be mediated by distinct regions of the protein.


Assuntos
Senescência Celular/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Genes Supressores de Tumor/fisiologia , Melanoma/genética , Neoplasias Cutâneas/genética , Animais , Animais Recém-Nascidos , Ciclo Celular/fisiologia , Células Cultivadas , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Fibroblastos/citologia , Fibroblastos/fisiologia , Melanoma/patologia , Camundongos , Estresse Oxidativo/genética , Mutação Puntual/genética , Estrutura Terciária de Proteína/genética , Espécies Reativas de Oxigênio/metabolismo , Neoplasias Cutâneas/patologia , Relação Estrutura-Atividade
19.
FEBS Lett ; 587(2): 136-41, 2013 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-23178718

RESUMO

Coevolution between proteins is crucial for understanding protein-protein interaction. Simultaneous changes allow a protein complex to maintain its overall structural-functional integrity. In this study, we combined statistical coupling analysis (SCA) and molecular dynamics simulations on the CDK6-CDKN2A protein complex to evaluate coevolution between proteins. We reconstructed an inter-protein residue coevolution network, consisting of 37 residues and 37 interactions. It shows that most of the coevolved residue pairs are spatially proximal. When the mutations happened, the stable local structures were broken up and thus the protein interaction was decreased or inhibited, with a following increased risk of melanoma. The identification of inter-protein coevolved residues in the CDK6-CDKN2A complex can be helpful for designing protein engineering experiments.


Assuntos
Quinase 6 Dependente de Ciclina/química , Quinase 6 Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/genética , Evolução Molecular , Genes p16 , Mutação , Quinase 6 Dependente de Ciclina/antagonistas & inibidores , Desenho de Fármacos , Humanos , Melanoma/etiologia , Melanoma/genética , Modelos Moleculares , Simulação de Dinâmica Molecular , Complexos Multiproteicos/química , Complexos Multiproteicos/genética , Proteínas Mutantes/química , Proteínas Mutantes/genética , Oncogenes , Domínios e Motivos de Interação entre Proteínas , Inibidores de Proteínas Quinases/farmacologia
20.
Biosens Bioelectron ; 42: 503-11, 2013 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-23246658

RESUMO

The hypermethylated tumor suppressor gene promoters are widely recognized as promising markers for cancer screening and ideal targets for cancer therapy, however, a major obstacle in their clinical study is highly sensitive screening. To address this limitation, we developed a novel bisulfite-microfluidic temperature gradient capillary electrophoresis (bisulfite-µTGCE) platform for gene methylation analysis by combining bisulfite treatment and slantwise radiative heating system-based µTGCE. Bisulfite-treated genomic DNA (gDNA) was amplified with universal primers for both methylated and unmethylated sequences, and introduced into glass microfluidic chip to perform electrophorectic separation under a continuous temperature gradient based on the formation of heteroduplexes. Eight CDKN2A promoter model fragments with different number and location of methylation sites were prepared and successfully analyzed according to their electrophoretic peak patterns, with high stability, picoliter-scale sample consumption, and significantly increased detection speed. The bisulfite-µTGCE could detect methylated gDNA with a detection limit of 7.5pg, and could distinguish as low as 0.1% methylation level in CDKN2A in an unmethylated background. Detection of seven colorectal cancer (CRC) cell lines with known and unknown methylation statuses of CDKN2A promoter and 20 tumor tissues derived from CRC patients demonstrated the capability of detecting hypermethylation in real-world samples. The wider adaptation of this platform was further supported by the detection of the CDKN2A and MLH1 promoters' methylation statuses in combination. This highly sensitive, fast, and low-consumption platform for methylation detection shows great potential for future clinical applications.


Assuntos
Metilação , Microfluídica/métodos , Regiões Promotoras Genéticas , Sulfitos/química , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/isolamento & purificação , Inibidor p16 de Quinase Dependente de Ciclina/química , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/isolamento & purificação , Fragmentação do DNA , Eletroforese em Gel de Gradiente Desnaturante , Humanos , Limite de Detecção , Proteína 1 Homóloga a MutL , Proteínas Nucleares/química , Proteínas Nucleares/isolamento & purificação
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