RESUMO
BACKGROUND: Glioma is the most prevalent malignant tumor in human central nervous systems. Recently, the development of resistance to radiotherapy in glioma patients markedly vitiates the therapy outcome. MiR-153-3p has been reported to be closely correlated with tumor progression, but its effect and molecular mechanism underlying radioresistance remains unclear in glioma. METHODS: The expression of miR-153-3p was determined in radioresistant glioma clinical specimens as well as glioma cell lines exposed to irradiation (IR) using quantitative real-time PCR. Cell viability, proliferation and apoptosis were then evaluated by MTT assay, colony formation assay, Flow cytometry analysis and caspase-3 activity assay in glioma cells (U87 and U251). Tumor forming was evaluated by nude mice model in vivo. TUNEL staining was used to detect cell apoptosis in nude mice model. The target genes of miR-153-3p were predicted and validated using integrated bioinformatics analysis and a luciferase reporter assay. RESULTS: Here, we found that miR-153-3p was down-regulated in radioresistant glioma clinical specimens as well as glioma cell lines (U87 and U251) exposed to IR. Enhanced expression of miR-153-3p promoted the radiosensitivity, promoted apoptosis and elevated caspase-3 activity in glioma cells in vitro, as well as the radiosensitivity in U251 cell mouse xenografs in vivo. Mechanically, B cell lymphoma-2 gene (BCL2) was identified as the direct and functional target of miR-153-3p. Moreover, restoration of BCL2 expression reversed miR-153-3p-induced increase of radiosensitivity, apoptosis and caspase-3 activity in U251 cells in vitro. In addition, clinical data indicated that the expression of miR-153-3p was significantly negatively associated with BCL2 in radioresistance of glioma samples. CONCLUSIONS: Our findings suggest that miR-153-3p is a potential target to enhance the effect of radiosensitivity on glioma cells, thus representing a new potential therapeutic target for glioma.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Tolerância a Radiação/genética , Genes bcl-2/fisiologia , MicroRNAs/efeitos da radiação , MicroRNAs/fisiologia , Glioma/genética , Fatores de Tempo , Regulação para Baixo , Regulação Neoplásica da Expressão Gênica , Sobrevivência Celular/efeitos da radiação , Western Blotting , Análise de Variância , Marcação de Genes/métodos , Genes bcl-2/efeitos da radiação , Marcação In Situ das Extremidades Cortadas , MicroRNAs/análise , Linhagem Celular Tumoral , Proliferação de Células/efeitos da radiação , Caspase 3/análise , Reação em Cadeia da Polimerase em Tempo Real , Citometria de Fluxo , Glioma/radioterapiaRESUMO
Summary The aim of this study is to describe the biogenesis of microRNA, its relations with carcinogenesis, and the correlation between microRNA and ionizing radiation (IR), focusing on radioresponsiveness. It is known that microRNA biogenesis is well established and involves different enzymatic cleavages, resulting in the production of mature microRNA. MicroRNAs are involved in carcinogenesis. Their interaction is related to the genetic and epigenetic changes associated with activation of proto-oncogenes or inactivation of tumor suppressor genes. Several studies have shown that the levels of expression of some microRNAs vary significantly after irradiation. There are evidences that microRNAs can influence cellular response after IR. In addition, microRNAs are related to modulation of the expression of several post-transcriptional targets in DNA damage response pathways, and to the DNA damage repair regulation mechanism. Future studies can clarify a possible clinical use of microRNAs as a new class of radiosensitive agents.
Resumo O objetivo do presente estudo é descrever a biogênese do microRNA, suas relações na carcinogênese e a correlação do microRNA com a radiação ionizante (RI), com enfoque na radiorresponsividade. Observou-se que a biogênese do microRNA está bem estabelecida e envolve diversas clivagens enzimáticas que resultam na produção do microRNA maduro. Os microRNAs estão envolvidos na carcinogênese. Sua interação está relacionada às alterações genéticas e epigenéticas, associadas à ativação de proto- -oncogenes ou à inativação de genes supressores de tumor. Vários estudos demonstraram que os níveis de expressão de alguns microRNAs variam significativamente após a irradiação. Há evidências de que os microRNAs podem influenciar a resposta celular após a RI. Além disso, os microRNAs estão relacionados à modulação da expressão de vários alvos de pós-transcrição das vias de resposta aos danos no DNA e o do mecanismo de regulação de reparação de danos do DNA. Estudos futuros podem elucidar uma possível utilização clínica dos microRNAs como uma nova classe de agentes radiossensíveis.