SRPK1/MAP4信号轴调控骨肉瘤转移的机制和功能研究

骨肉瘤是儿童和青少年最常见的原发恶性骨肿瘤，远处转移是其最常见的死亡因素。目前，骨肉瘤的转移机制尚不清楚，缺乏有效的治疗手段。面对这一治疗困境，申请人前期通过转录组学和临床数据生存分析发现SRPK1与骨肉瘤的转移密切相关，抑制SRPK1可显著降低骨肉瘤细胞的增殖、转移。进一步的机制研究中，申请人发现SRPK1能够与MAP4相结合并特异性磷酸化MAP4的S896位点，并且SRPK1能调控MAP4蛋白稳定性。同时还发现抑制SRPK1，骨肉瘤细胞微管稳定性降低，而SRPK1抑制剂也可显著降低骨肉瘤的成瘤和肺转移，提示SRPK1可能通过调控微管稳定性影响骨肉瘤转移。基于以上数据，本课题拟进一步阐释SRPK1调控MAP4的分子机制，明确SRPK1/MAP4信号轴对微管稳定性和骨肉瘤转移的调控作用，探寻SPRK1抑制剂SPHINX31对骨肉瘤转移的疗效，为骨肉瘤转移的治疗提供新的药物靶点和理论基础。

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, and the most common cause of death for osteosarcoma is distant metastasis. At present, the metastasis mechanism of osteosarcoma is still unclear, and there is a lack of effective treatment methods. Faced with this dilemma, we found that protein kinase SRPK1 is closely related to the invasion and metastasis of osteosarcoma through transcriptomics and clinical data survival analysis. Inhibition of SRPK1 can significantly reduce the proliferation and metastasis of osteosarcoma cells. In further research on the mechanism, we found that SRPK1 can bind to MAP4 and specifically phosphorylate the S896 site of MAP4. Besides, SRPK1 can regulate the protein stability of MAP4. Since the phosphorylation level of MAP4 is closely related to the stability of microtubules, we inhibited SRPK1 and found that the microtubule stability of osteosarcoma cells was reduced, and SRPK1 inhibitor could also significantly reduce the tumorigenesis and lung metastasis of osteosarcoma, suggesting that SRPK1 can probably affect the occurrence and metastasis of osteosarcoma by regulating microtubules stability. Based on the above evidence, we intend to further explain the molecular mechanism by which SRPK1 regulates MAP4, clarify the regulation of SRPK1/MAP4 signal axis on microtubule stability and osteosarcoma metastasis, and explore the curative effect of SPHINX31, the SPRK1 inhibitor, on osteosarcoma metastasis, in order to provide a new drug target and theoretical basis for the treatment of osteosarcoma metastasis.