转录因子MYBL1调控自噬诱导骨肉瘤化疗耐药的研究

化疗耐药是骨肉瘤患者治疗失败的主要原因，研究表明自噬的诱导可促进化疗耐药，但自噬的调控机制尚未充分阐明。申请人在前期研究中首次发现MYBL1下调可以增强骨肉瘤细胞对化疗的敏感性，MYBL1通过何种分子机制发挥该功能尚无文献报道。我们应用基因芯片技术发现在化疗药物作用下MYBL1下调可抑制自噬，且透射电镜等实验验证了该发现。应用ChIP-seq发现MYBL1能够与自噬激活分子HMGB1的启动子区结合，且荧光素酶报告揭示MYBL1的下调可以抑制HMGB1的转录活性。因此，本申请项目提出MYBL1调控HMGB1的转录活性诱导自噬，从而促进骨肉瘤化疗耐药的假说。我们拟采用EMSA等分子生物学技术、动物模型、人体组织标本，研究MYBL1在体内体外发挥的功能，揭示MYBL1诱导骨肉瘤化疗耐药的分子机制。本课题可能对阐明骨肉瘤化疗耐药机制有重要意义，也为逆转化疗耐药及自噬抑制剂的应用提供精准标志物。

Chemotherapy resistance is the main cause of treatment failure in osteosarcoma patients. Previous studies showed that induction of autophagy contributes to chemotherapy resistance, however the mechanisms underlying the regulation of autophagy have not been fully elucidated. We firstly found MYBL1 knockdown increased the sensitivity of osteosarcoma cells to chemotherapy drugs. But the relationship between MYBL1 and chemo-resistance has not been elucidated in osteosarcoma. Microarray analysis suggested that MYBL1 knockdown inhibited autophagy in osteosarcoma cells, which was verified by transmission electron microscopy assessment of autophagosome and autophagy-lysosome. Using ChIP-seq, we found that MYBL1 could bind HMGB1 gene promoter region which is an activator of autophagy. Moreover, MYBL1 knockdown inhibited HMGB1 transcriptional activity using luciferase report. We hypothesized that MYBL1 could promote transcriptional activity of HMGB1 to promote chemoresistance by modulating autophagy. Therefore, we are planning to study the function and mechanism of MYBL1 regulating osteosarcoma chemoresistance, by means of molecular biology technology including EMSA, xenograft models and patient tissue samples. This study may provide valuable information to investigate the mechanism of chemotherapy resistance and the precis biomarker for reversion of chemoresistance and application of autophagy inhibitors in osteosarcoma.