骨肉瘤中融合蛋白RAB22A-NeoF1的降解调控机制及临床意义

骨肉瘤恶性程度高、对放化疗均不敏感，尚无靶向药物。我们前期发现了一个新的骨肉瘤融合基因RAB22A-NeoF1，该融合蛋白可持续结合SmgGDS活化RhoA，促进骨肉瘤的肺转移。但目前尚不清楚该融合蛋白是如何被调控的，我们最近结果表明：该融合蛋白可能被NDP52介导的自噬溶酶体降解，其E3泛素连接酶可能是STUB1；PINK1可促进该降解过程，靶向药物索拉菲尼可上调PINK1从而抑制该融合蛋白所致的迁移和侵袭。本项目拟：进一步明确该融合蛋白是通过被NDP52介导的自噬溶酶体降解，STUB1是其E3泛素连接酶，并鉴定其泛素化位点；进一步明确PINK1是通过磷酸化该融合蛋白而调控其功能，并鉴定其磷酸化位点；探讨索拉菲尼靶向PINK1/RAB22A-NeoF1通路在骨肉瘤肺转移中的临床意义。本项目的完成，将明确RAB22A-NeoF1融合蛋白在骨肉瘤中的调控机制，为骨肉瘤肺转移的治疗提供新策略。

Osteosarcoma, a high malignant tumor, is not sensitive to the current radio- and chemo-therapies, and there is no targeted drug for this cancer so far. We have previously identified a new osteosarcoma fusion gene RAB22A-NeoF1, which continuously binds to SmgGDS to activate RhoA and promote osteosarcoma lung metastasis. But how this fusion protein is regulated remain unclear. Our recent results show that this fusion protein may be degraded by the NDP52-mediated autophagy via lysosome, and that its E3 ligase may be STUB1; PINK1 promotes this degradation process, and sorafenib as a targeted drug can up-regulate PINK1 to inhibit the migration and invasion induced by this fusion protein. This project intends to further clarify that this fusion protein is degraded by autophagy mediated by NDP52 through lysosome, STUB1 is its E3 ligase, and identifies its ubiquitination site; and that PINK1 regulates its function by phosphorylating this fusion protein and its phosphorylation site will be identified; and explores the clinical significance of sorafenib by targeting the PINK1/RAB22A-NeoF1 pathway in osteosarcoma lung metastasis. The completion of this project will demonstrate the regulatory mechanism of RAB22A-NeoF1 fusion protein in osteosarcoma, and provide new strategies for the treatment of osteosarcoma lung metastasis.