以PERK为靶点抑制内质网应激性自噬在逆转骨肉瘤光动力疗法耐受中的作用和机制

光动力疗法(photodynamic therapy，PDT)是继手术、放疗、化疗之后又一肿瘤治疗新方法，可用于骨肉瘤的临床治疗。然而骨肉瘤对PDT具有耐受性，因此了解骨肉瘤PDT耐受形成的机制并加以干预将有利于PDT在骨肉瘤治疗中的应用。前期发现PDT可诱导骨肉瘤细胞发生具有细胞保护效应的内质网应激性自噬，并伴有内质网应激相关蛋白激酶R样内质网激酶（PERK）磷酸化水平上调，这提示内质网应激性自噬参与骨肉瘤PDT耐受的形成，但该过程是否通过PERK信号通路介导以及以PERK为干预靶点能否逆转骨肉瘤PDT耐受尚待进一步研究。本研究拟以骨肉瘤细胞和裸鼠荷瘤模型为研究对象，研究PDT所致的内质网应激性自噬，并揭示PERK介导内质网应激性自噬的具体机制；探讨以PERK为干预靶点抑制内质网应激性自噬最终逆转骨肉瘤PDT耐受的有效性。研究结果将为逆转骨肉瘤PDT耐受提供新的靶点和研究思路

Photodynamic therapy is a new anti-tumor treatment method after surgical operation, radiotherapy and chemotherapy, and can be used in clinical treatment of osteosarcoma. PDT- resistance remains to be solved before photodynamic therapy as a clinical application. To understand the mechanism of PDT-resistance for osteosarcoma treatment and take targeted intervention will be conducive to PDT applications. Our previous work found that PDT could induce endoplasmic reticulum stress-induced autophagy in osteosarcoma cells which played cytoprotective effects, accompanied by protein kinase-like endoplasmic reticulum kinase (PERK) phosphorylation level increased. This suggests that endoplasmic reticulum stress-induced autophagy is involved in osteosarcoma PDT-resistance. However, whether it is mediated by PERK signaling pathway and targeted intervene PERK can reverse PDT-resistance need further study. We aim to investigate endoplasmic reticulum stress-induced autophagy and reveal the mechanisms of PERK-mediated endoplasmic reticulum stress-induced autophagy in osteosarcoma PDT based on cells level and tumor-bearing nude mouse model, and confirm targeting intervention for PERK inhibit endoplasmic reticulum stress-induced autophagy eventually reverse the PDT-resistance. The results will provide new insight into reversing osteosarcoma PDT resistance.