development of survivin targeted therapy for Adult T-cell leukemia/lymphoma

Survivin是一种凋亡蛋白抑制剂，在成人t细胞白血病/淋巴瘤（ATL）中高表达，并与化疗耐药有关。survivin特异性过表达在几乎所有人类恶性肿瘤中都有报道，但在正常组织中未检测到，这使得survivin靶向治疗成为一种有吸引力的ATL治疗策略。Survivin作为一种同型二聚体，通过n端单球状杆状病毒IAP重复（BIR）结构域与XIAP相互作用，保护XIAP免于泛素化，提高其稳定性，促进caspase-9抑制。本研究合成了Val89和Lys103之间形成同型二聚体的survivin序列（PTD-(89-103aa)）和Lys15和Met38之间与XIAP相互作用的序列（PTD-(15-38aa)），将TAT蛋白的蛋白转导结构域（PTD）添加到它们的氨基末端，使其具有细胞通透性。PTD-(15-38aa)作用2小时后，多种白血病细胞株（ATL细胞株S1T和MT2、白血病细胞株c…More细胞株HL60、NB4、K562、Jurkat）的生长均受到强烈抑制。而对正常细胞系、肺成纤维细胞HEL和正常人脐静脉内皮细胞HUVEC均无抑制作用。PTD-(15-38aa)作用2h后，Giemsa染色观察到S1T细胞明显死亡。Annexin V和PI染色的FACS估计S1T细胞的凋亡比例呈剂量依赖性增加。然而，免疫印迹未检测到caspase-9、caspase-3和PARP的降解。出乎意料的是，我们发现PTD-(15-38aa)处理引起LC3-II表达的剂量依赖性增加和p62表达的减少。这些结果表明自噬参与了PTD-(15-38aa)-诱导的S1T细胞凋亡。采用免疫沉淀法研究PTD-(15-38aa)对Flag-XIAP和Myc-survivin共转染的COS细胞中survivin与XIAP相互作用的影响。与预期相反，PTD-(15-38aa)剂量依赖性地增强了survivin与XIAP的结合。这些结果表明，PTD-(15-38aa)对白血病细胞，特别是ATL细胞的增殖有较强的抑制作用，而PTD-(15-38aa)对自噬介导的细胞凋亡的诱导与caspase激活无关。少

Survivin, an inhibitor of apoptosis protein, is highly expressed in adult T-cell leukemia/lymphoma (ATL), and associated with chemotherapy resistance. Specifically overexpression of survivin has been reported in almost all human malignancies, but not detectable in normal tissues, making survivin targeted therapy an attractive ATL therapy strategy. Survivin is functioning as a homodimer, and interacts with XIAP through N-terminal single globular baculovirus IAP repeat (BIR) domain, protecting XIAP from ubiquitination and increasing its stability that promotes caspase-9 inhibition. In this study, peptides containing the survivin sequence for homodimer formation between Val89 and Lys103 (PTD-(89-103aa)), and the sequence for interacting with XIAP between Lys15 and Met38 (PTD-(15-38aa)), adding the protein transduction domains (PTD) of TAT protein to their amino-terminals for cell permeable, were synthesized. The growth of various leukemia cell lines (ATL cell lines S1T and MT2, leukemia c … More ell lines HL60, NB4, K562, Jurkat) was strongly inhibited after 2 hr incubation with PTD-(15-38aa). However, no growth suppression was observed in the normal cell lines, lung fibroblast cells HEL and Normal Human Umbilical Vein Endothelial Cells HUVEC. Significant cell death of S1T cells was observed after 2hr treatment with PTD-(15-38aa) by Giemsa staining. The proportion of apoptosis fraction estimated by FACS with Annexin V and PI staining in S1T cells was increased in the dose dependent manner. However, Degradation of caspase-9, caspase-3 and PARP was not detected by immunoblotting. Unexpectedly, we found that PTD-(15-38aa) treatment caused a dose dependent increase in the expression of LC3-II and decrease in the expression of p62. These results indicated that autophagy involved in the PTD-(15-38aa)-induced apoptosis in S1T cells. The effect of PTD-(15-38aa) on the interacting of survivin with XIAP was investigated in COS cells co-transfected with Flag-XIAP and Myc-survivin by immunopreciptation. Contrary to expectation, PTD-(15-38aa) dose dependently enhanced the binding of survivin with XIAP. These results suggested that PTD-(15-38aa) strongly inhibited the proliferation of leukemia cells, specifically ATL cells, and caspase activation is not involved in the induction of autophagy- mediated apoptosis by PTD-(15-38aa). Less