RESUMO
BACKGROUND: Human homeobox genes encode nuclear proteins that act as transcription factors involved in the control of differentiation and proliferation. Currently, the role of these genes in development and tumor progression has been extensively studied. Recently, increased expression of HOXB7 homeobox gene (HOXB7) in pancreatic ductal adenocarcinomas (PDAC) was shown to correlate with an invasive phenotype, lymph node metastasis and worse survival outcomes, but no influence on cell proliferation or viability was detected. In the present study, the effects arising from the knockdown of HOXB7 in PDAC cell lines was investigated. METHODS: Real time quantitative PCR (qRT-PCR) (Taqman) was employed to assess HOXB7 mRNA expression in 29 PDAC, 6 metastatic tissues, 24 peritumoral tissues and two PDAC cell lines. siRNA was used to knockdown HOXB7 mRNA in the cell lines and its consequences on apoptosis rate and cell proliferation were measured by flow cytometry and MTT assay respectively. RESULTS: Overexpression of HOXB7 mRNA was observed in the tumoral tissues and in the cell lines MIA PaCa-2 and Capan-1. HOXB7 knockdown elicited (1) an increase in the expression of the pro-apoptotic proteins BAX and BAD in both cell lines; (2) a decrease in the expression of the anti-apoptotic protein BCL-2 and in cyclin D1 and an increase in the number of apoptotic cells in the MIA PaCa-2 cell line; (3) accumulation of cell in sub-G1 phase in both cell lines; (4) the modulation of several biological processes, especially in MIA PaCa-2, such as proteasomal ubiquitin-dependent catabolic process and cell cycle. CONCLUSION: The present study confirms the overexpression of HOXB7 mRNA expression in PDAC and demonstrates that decreasing its protein level by siRNA could significantly increase apoptosis and modulate several biological processes. HOXB7 might be a promising target for future therapies.
Assuntos
Apoptose/genética , Carcinoma Ductal Pancreático/genética , Pontos de Checagem do Ciclo Celular/genética , Regulação Neoplásica da Expressão Gênica , Proteínas de Homeodomínio/genética , Neoplasias Pancreáticas/genética , RNA Mensageiro , Carcinoma Ductal Pancreático/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Fatores de Transcrição E2F/genética , Dosagem de Genes , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Inativação Gênica , Humanos , Neoplasias Pancreáticas/metabolismo , RNA Interferente Pequeno/genética , Reprodutibilidade dos Testes , Proteína do Retinoblastoma/genéticaRESUMO
Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive decline, including memory loss, behavioral and psychological symptoms and personality changes. The neuropathological hallmarks of AD are the presence of neuritic (senile) plaques (NP) and neurofibrillary tangles (NFT), along with neuronal loss, dystrophic neurites, and gliosis. Neuritic plaques are extracellular lesions and their main constituent is the amyloid-ß42 peptide (Aß42). Neurofibrillary tangles are intracellular lesions that are mainly composed of hyperphosphorylated Tau protein. In this article, we review the major hypotheses concerning the physiopathology of AD, focusing on the ß-amyloid cascade as primary events (supported by the "ßaptists") and cytoskeletal abnormalities secondary to the hyperphosphorylation of protein Tau (as advocated by the "Tauists"). We further provide an integrative view of the physiopathology of AD.
A doença de Alzheimer (DA) é uma desordem neurodegenerativa progressiva que cursa comprometimento da memória e outras funções cognitivas, alterações comportamentais, psíquicas e da personalidade. Os achados neuropatológicos característicos da DA são as placas neuríticas (senis) e os emaranhados neurofibrilares, também ocorrendo distrofia de neuritos, gliose e perda neuronal. As placas neuríticas são lesões extracelulares que têm no peptídeo beta-amilóide (Aß42) seu principal constituinte. Os emaranhados neurofibrilares são lesões intraneuronais compostas por agregados de proteína TAU em estado hiperfosforilado. Neste artigo de revisão, apresentamos as principais hipóteses relacionadas à fisiopatologia da DA, com foco na cascata do amilóide como evento inicial (hipótese preconizada pelos "ßaptistas") e nas alterações do citoesqueleto neuronal, decorrentes da fosforilação anormal da TAU (conforme proposto pelos "tauístas"). Os achados são discutidos numa leitura integrada desses dois mecanismos fisiopatológicos.