RESUMO
PTP1B plays a key role in developing different types of cancer. However, the molecular mechanism underlying this effect is unclear. To identify molecular targets of PTP1B that mediate its role in tumorigenesis, we undertook a SILAC-based phosphoproteomic approach, which allowed us to identify Cdk3 as a novel PTP1B substrate. Substrate trapping experiments and docking studies revealed stable interactions between the PTP1B catalytic domain and Cdk3. In addition, we observed that PTP1B dephosphorylates Cdk3 at tyrosine residue 15 in vitro and interacts with it in human glioblastoma cells. Next, we found that pharmacological inhibition of PTP1B or its depletion with siRNA leads to cell cycle arrest with diminished activity of Cdk3, hypophosphorylation of Rb, and the downregulation of E2F target genes Cdk1, Cyclin A, and Cyclin E1. Finally, we observed that the expression of a constitutively active Cdk3 mutant bypasses the requirement of PTP1B for cell cycle progression and expression of E2F target genes. These data delineate a novel signaling pathway from PTP1B to Cdk3 required for efficient cell cycle progression in an Rb-E2F dependent manner in human GB cells.
Assuntos
Glioblastoma , Humanos , Glioblastoma/genética , Divisão Celular , Transdução de Sinais , Pontos de Checagem do Ciclo Celular , Ciclo Celular/fisiologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismoRESUMO
In 2013, recognizing that Colorectal Cancer (CRC) is the second leading cause of death by cancer worldwide and that it was a neglected disease increasing rapidly in Mexico, the community of researchers at the Biomedicine Research Unit of the Facultad de Estudios Superiores Iztacala from the Universidad Nacional Autónoma de México (UNAM) established an intramural consortium that involves a multidisciplinary group of researchers, technicians, and postgraduate students to contribute to the understanding of this pathology in Mexico. This article is about the work developed by the Mexican Colorectal Cancer Research Consortium (MEX-CCRC): how the Consortium was created, its members, and its short- and long-term goals. Moreover, it is a narrative of the accomplishments of this project. Finally, we reflect on possible strategies against CRC in Mexico and contrast all the data presented with another international strategy to prevent and treat CRC. We believe that the Consortium's characteristics must be maintained to initiate a national strategy, and the reported data could be useful to establish future collaborations with other countries in Latin America and the world.
Assuntos
Neoplasias Colorretais , Estudantes , Humanos , México , Estudos Interdisciplinares , Terapias em Estudo , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/terapiaRESUMO
Protein tyrosine phosphorylation is one of the major post-translational modifications in eukaryotic cells and represents a critical regulatory mechanism of a wide variety of signaling pathways. Aberrant protein tyrosine phosphorylation has been linked to various diseases, including metabolic disorders and cancer. Few years ago, protein tyrosine phosphatases (PTPs) were considered as tumor suppressors, able to block the signals emanating from receptor tyrosine kinases. However, recent evidence demonstrates that misregulation of PTPs activity plays a critical role in cancer development and progression. Here, we will focus on PTP1B, an enzyme that has been linked to the development of type 2 diabetes and obesity through the regulation of insulin and leptin signaling, and with a promoting role in the development of different types of cancer through the activation of several pro-survival signaling pathways. In this review, we discuss the molecular aspects that support the crucial role of PTP1B in different cellular processes underlying diabetes, obesity and cancer progression, and its visualization as a promising therapeutic target.
Assuntos
Doenças Metabólicas/etiologia , Doenças Metabólicas/metabolismo , Neoplasias/etiologia , Neoplasias/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Transdução de Sinais , Animais , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/metabolismo , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Humanos , Doenças Metabólicas/tratamento farmacológico , Neoplasias/tratamento farmacológico , Obesidade/tratamento farmacológico , Obesidade/etiologia , Obesidade/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/química , Transdução de Sinais/efeitos dos fármacosRESUMO
Lysophosphatidic acid (LPA) induces a wide range of cellular processes and its signaling is increased in several cancers including glioblastoma (GBM), a high-grade astrocytoma, which is the most common malignant brain tumor. LPA1 receptor is expressed in GBM cells and its signaling pathways activate protein kinases C (PKCs). A downstream target of PKC, involved in GBM progression, is the intracellular progesterone receptor (PR), which can be phosphorylated by this enzyme, increasing its transcriptional activity. Interestingly, in GBM cells, PKCα isotype translocates to the nucleus after LPA stimulation, resulting in an increase in PR phosphorylation. In this study, we determined that LPA1 receptor activation induces protein-protein interaction between PKCα and PR in human GBM cells; this interaction increased PR phosphorylation in serine400. Moreover, LPA treatment augmented VEGF transcription, a known PR target. This effect was blocked by the PR selective modulator RU486; also, the activation of LPA1/PR signaling promoted migration of GBM cells. Interestingly, using TCGA data base, we found that mRNA expression of LPAR1 increases according to tumor malignancy and correlates with a lower survival in grade III astrocytomas. These results suggest that LPA1/PR pathway regulates GBM progression.
Assuntos
Neoplasias Encefálicas/metabolismo , Glioblastoma/metabolismo , Proteína Quinase C-alfa/metabolismo , Receptores de Ácidos Lisofosfatídicos/metabolismo , Receptores de Progesterona/metabolismo , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Receptores ErbB/genética , Receptores ErbB/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Lisofosfolipídeos/farmacologia , Diester Fosfórico Hidrolases/metabolismo , Fosforilação/efeitos dos fármacos , Fosfosserina/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Sobrevida , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
p21-Activated kinase-1 (Pak1) is frequently overexpressed and/or amplified in human breast cancer and is necessary for transformation of mammary epithelial cells. Here, we show that Pak1 interacts with and phosphorylates the Calcium/Calmodulin-dependent Protein Kinase II (CaMKII), and that pharmacological inhibition or depletion of Pak1 leads to diminished activity of CaMKII. We found a strong correlation between Pak1 and CaMKII expression in human breast cancer samples, and combined inhibition of Pak1 and CaMKII with small-molecule inhibitors was synergistic and induced apoptosis more potently in Her2 positive and triple negative breast cancer (TNBC) cells. Co-adminstration of Pak and CaMKII small-molecule inhibitors resulted in a dramatic reduction of proliferation and an increase in apoptosis in a 3D cell culture setting, as well as an impairment in migration and invasion of TNBC cells. Finally, mice bearing xenografts of TNBC cells showed a significant delay in tumor growth when treated with small-molecule inhibitors of Pak and CaMKII. These data delineate a signaling pathway from Pak1 to CaMKII that is required for efficient proliferation, migration and invasion of mammary epithelial cells, and suggest new therapeutic strategies in breast cancer.
RESUMO
The estrogen receptor alpha (ERα) is a ligand-activated transcription factor whose activity is modulated by its interaction with multiple protein complexes. In this work, we have identified the protein interferon alpha inducible protein 27 (IFI27/ISG12) as a novel ERα-associated protein. IFI27/ISG12 transcription is regulated by interferon and estradiol and its overexpression is associated to reduced overall survival in ER+ breast cancer patients but its function in mammary gland tissue remains elusive. In this study we showed that overexpression of IFI27/ISG12 in breast cancer cells attenuates ERα transactivation activity and the expression of ERα-dependent genes. Our results demonstrated that IFI27/ISG12 overexpression in MCF-7 cells reduced their proliferation rate in 2-D and 3-D cell culture assays and impaired their ability to migrate in a wound-healing assay. We show that IFI27/ISG12 downregulation of ERα transactivation activity is mediated by its ability to facilitate the interaction between ERα and CRM1/XPO1 that mediates the nuclear export of large macromolecules to the cytoplasm. IFI27/ISG12 overexpression was shown to impair the estradiol-dependent proliferation and tamoxifen-induced apoptosis in breast cancer cells. Our results suggest that IFI27/ISG12 may be an important factor in regulating ERα activity in breast cancer cells by modifying its nuclear versus cytoplasmic protein levels. We propose that IFI27/ISG12 may be a potential target of future strategies to control the growth and proliferation of ERα-positive breast cancer tumors.
Assuntos
Neoplasias da Mama/metabolismo , Regulação para Baixo/fisiologia , Receptor alfa de Estrogênio/biossíntese , Carioferinas/biossíntese , Proteínas de Membrana/biossíntese , Receptores Citoplasmáticos e Nucleares/biossíntese , Ativação Transcricional/fisiologia , Neoplasias da Mama/genética , Bases de Dados Genéticas , Regulação para Baixo/efeitos dos fármacos , Estradiol/farmacologia , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor alfa de Estrogênio/genética , Feminino , Humanos , Carioferinas/genética , Células MCF-7 , Proteínas de Membrana/genética , Receptores Citoplasmáticos e Nucleares/genética , Tamoxifeno/farmacologia , Ativação Transcricional/efeitos dos fármacos , Proteína Exportina 1RESUMO
Inflammation is currently considered a hallmark of cancer and plays a decisive role in different stages of tumorigenesis, including initiation, promotion, progression, metastasis and resistance to antitumor therapies. Colorectal cancer is a disease widely associated with local chronic inflammation. Additionally, extrinsic factors such as infection may beneficially or detrimentally alter cancer progression. Several reports have noted the ability of various parasitic infections to modulate cancer development, favoring tumor progression in many cases and inhibiting tumorigenesis in others. The aim of our study was to determine the effects of excreted/secreted products of the helminth Taenia crassiceps (TcES) as a treatment in a murine model of colitis-associated colon cancer (CAC). Here, we found that after inducing CAC, treatment with TcES was able to reduce inflammatory cytokines such as IL-1ß, TNF-α, IL-33 and IL-17 and significantly attenuate colon tumorigenesis. This effect was associated with the inhibition of signal transducer and activator of transcription 3 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) phosphorylation. Furthermore, we determined that TcES interfered with LPS-induced NF-κB p65 activation in human colonic epithelial cell lines in a Raf-1 proto-oncogene-dependent manner. Moreover, in three-dimensional cultures, TcES promoted reorganization of the actin cytoskeleton, altering cell morphology and forming colonospheres, features associated with a low grade of aggressiveness. Our study demonstrates a remarkable effect of helminth-derived molecules on suppressing ongoing colorectal cancer by downregulating proinflammatory and protumorigenic signaling pathways.
Assuntos
Anti-Inflamatórios/administração & dosagem , Azoximetano/efeitos adversos , Colite/tratamento farmacológico , Neoplasias do Colo/tratamento farmacológico , Proteínas de Helminto/administração & dosagem , Taenia/metabolismo , Animais , Anti-Inflamatórios/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colite/induzido quimicamente , Colite/complicações , Neoplasias do Colo/etiologia , Modelos Animais de Doenças , Feminino , Proteínas de Helminto/farmacologia , Humanos , Interleucina-1beta/metabolismo , Interleucina-33/metabolismo , Camundongos , NF-kappa B/metabolismo , Fosforilação , Proto-Oncogene Mas , Fator de Transcrição STAT3/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Cells that are deficient in homologous recombination, such as those that have mutations in any of the Fanconi Anemia (FA)/BRCA genes, are hypersensitive to inhibition of poly(ADP-ribose) polymerase (PARP). However, FA/BRCA-deficient tumors represent a small fraction of breast cancers, which might restrict the therapeutic utility of PARP inhibitor monotherapy. The gene encoding the serine-threonine protein kinase p21-activated kinase 1 (PAK1) is amplified and/or overexpressed in several human cancer types including 25-30% of breast tumors. This enzyme controls many cellular processes by phosphorylating both cytoplasmic and nuclear substrates. Here, we show that depletion or pharmacological inhibition of PAK1 down-regulated the expression of genes involved in the FA/BRCA pathway and compromised the ability of cells to repair DNA by Homologous Recombination (HR), promoting apoptosis and reducing colony formation. Combined inhibition of PAK1 and PARP in PAK1 overexpressing breast cancer cells had a synergistic effect, enhancing apoptosis, suppressing colony formation, and delaying tumor growth in a xenograft setting. Because reduced PAK1 activity impaired FA/BRCA function, inhibition of this kinase in PAK1 amplified and/or overexpressing breast cancer cells represents a plausible strategy for expanding the utility of PARP inhibitors to FA/BRCA-proficient cancers.
Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Resistencia a Medicamentos Antineoplásicos , Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Quinases Ativadas por p21/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Cromossomos Humanos Par 11/genética , Dano ao DNA/efeitos dos fármacos , Modelos Animais de Doenças , Resistencia a Medicamentos Antineoplásicos/genética , Sinergismo Farmacológico , Proteínas de Grupos de Complementação da Anemia de Fanconi/deficiência , Feminino , Amplificação de Genes , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Recombinação Homóloga , Humanos , Camundongos , Ensaios Antitumorais Modelo de Xenoenxerto , Quinases Ativadas por p21/genéticaRESUMO
In this work we have determined the role of the 26S proteasome in the regulation of the content of progesterone receptors (PR-A and PR-B), estrogen receptors (ER-alpha and ER-beta), the coactivator SRC-1 and the corepressor SMRT in the rat brain during the estrous cycle. The 26S proteasome inhibitor MG132 was injected once into the lateral ventricle on proestrous day; and 24h later, on estrous day we evaluated the content of PR and ER isoforms, SRC-1 and SMRT in the hypothalamus, the preoptic area and the hippocampus by Western blot. A significant increase in the content of both PR isoforms, ER-beta and SRC-1 was observed after the administration of MG132 in the three studied cerebral regions. SMRT content was increased in the hypothalamus and the preoptic area and a significant increase in ER-alpha content was only observed in the preoptic area. These results suggest that essential proteins that participate in progesterone and estrogen actions in the brain should be regulated by the 26S proteasome in a tissue-specific manner in physiological conditions.
Assuntos
Encéfalo/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Ciclo Estral/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Progesterona/metabolismo , Complexo de Endopeptidases do Proteassoma/farmacologia , Receptores de Estrogênio/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Animais , Western Blotting/métodos , Encéfalo/metabolismo , Ciclo Estral/fisiologia , Feminino , Histona Acetiltransferases , Correpressor 2 de Receptor Nuclear , Coativador 1 de Receptor Nuclear , Ratos , Ratos WistarRESUMO
In this work, we determined the expression pattern and the hormonal regulation of progesterone receptor (PR) isoforms in the rat lung of ovariectomized female rats after estradiol (E2) and progesterone (P4) treatments. We also evaluated the content of estrogen receptor beta (ER-beta) which is the ER isoform expressed in the lung. RNA and proteins were extracted and processed for reverse transcription (RT) coupled to polymerase chain reaction (PCR) and Western blot, respectively. The expression of both PR isoforms in the lung at mRNA and at protein levels was up-regulated by E2 while P4 down-regulated it at mRNA level. P4 did not modify PR isoforms protein content unlike its effect in the uterus where both PR isoforms were down-regulated by their ligand at mRNA and protein levels. PR-A was the predominant isoform, both in the lung and in the uterus. In the lung, ER-beta was down-regulated by E2 while P4 did not significantly modify the effect of E2. These results suggest that both PR isoforms should be expressed in the rat lung, and that their expression should be differentially regulated at mRNA and at protein levels by P4. We also suggest that the up-regulation of PR isoforms by E2 in the lung is mediated by ER-beta.