Circ_0005721/PTBP1/BAK1分子轴促进骨肉瘤多药耐药的作用和机制研究

骨肉瘤是青少年最常见的原发性恶性骨肿瘤。化疗是其最重要的辅助疗法，然而多药耐药的出现极大影响了其治疗效果。环状RNA失调控与肿瘤化疗耐药的发生密切相关，但与骨肉瘤多药耐药相关特异环状RNA的报道较少。为此，我们前期通过RNA测序筛选及PCR验证，发现在骨肉瘤耐药细胞、组织和血清中均高表达且与患者不良预后密切相关的新环状RNAcirc_0005721，进而通过一系列研究初步验证发现circ_0005721可与重要的RNA结合蛋白PTBP1结合，并介导其从胞核转运至胞质，下调促凋亡基因BAK1的表达，促进骨肉瘤多药耐药，提示circ_0005721/PTBP1/BAK1分子轴可能参与了骨肉瘤多药耐药的调控过程。为验证以上假说，本研究拟采用基因干预、RIP及荧光素酶报告基因系统等技术阐明上述分子轴在体内外水平促进骨肉瘤多药耐药发生发展的作用和分子机制，有望为多药耐药骨肉瘤的精准治疗提供潜在靶点。

Osteosarcoma is the most common primary malignant bone tumor in adolescents. Chemotherapy is its most important adjuvant therapy, but the occurrence of multidrug resistance has greatly affected its therapeutic effect. The deregulation of circular RNA is closely related to the occurrence of tumor chemoresistance, but there are few reports about specific circular RNA related to multidrug resistance in osteosarcoma. For this reason, by use of RNA sequencing screening and PCR verification, we found that a new circular RNA ,circ_0005721, highly expressed in osteosarcoma drug-resistant cells, tissues and serum, is closely related to the poor prognosis of osteosarcoma patients; and through a series of studies, we preliminarily found that circ_0005721 could bind with the important RNA binding protein PTBP1 and mediate its transport from the nucleus to the cytoplasm, down-regulate the expression of the pro-apoptotic gene BAK1, and further promote multidrug resistance in osteosarcoma, suggesting that the circ_0005721/PTBP1/BAK1 molecular axis may be involved in the regulation of multidrug resistance of osteosarcoma. In order to verify the hypothesis above mentioned, the current study aims to use gene intervention, RIP and luciferase reporter gene system to clarify the role and molecular mechanism of circ_0005721/PTBP1/BAK1 molecular axis to promote the occurrence and development of multidrug resistance of osteosarcoma in vivo and in vitro, which is expected to provide some potential molecular targets for precise treatment of multidrug resistant osteosarcoma.