Hui Kwai Fung, Yeung Po Ling, Tam Kam Pui, Chiang Alan Kwok Shing
Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.
Oncotarget. 2018 May 18;9(38):25101-25114. doi: 10.18632/oncotarget.25341.
Combination of suberoylanilide hydroxamic acid (SAHA) and bortezomib (SAHA/bortezomib) was shown to synergistically induce killing of lymphoblastoid cell lines (LCL) and Burkitt lymphoma (BL) of type III or Wp-restricted latency, both of which express EBNA3A, -3B and -3C proteins. We hypothesize that SAHA/bortezomib can counteract the survival functions conferred by the EBNA3 proteins. We tested the effect of SAHA/bortezomib on the survival of BL cell lines containing EBNA3A, -3B or -3C knockout EBV with or without the respective revertant EBNA3 genes. Isobologram analysis showed that SAHA/bortezomib induced significantly greater synergistic killing of EBNA3C-revertant cells when compared with EBNA3C-knockout cells. Such differential response was not observed in either EBNA3A or -3B revertant versus their knockout pairs. Interestingly, EBNA3C-knockout cells showed significant G2/M arrest whilst EBNA3C-revertant cells and LCLs escaped G2/M arrest induced by SAHA/bortezomib and became more susceptible to the induction of apoptosis. In parallel, SAHA/bortezomib induced stronger expression of p21 but weaker expression of p-cdc25c, an M-phase inducer phosphatase, in EBNA3C-expressing cells when compared with EBNA3C-knockout cells. SAHA/bortezomib also induced greater growth suppression of EBNA3C-expressing xenografts (EBNA3C-revertant and LCL) than that of EBNA3C-knockout xenografts in SCID mice. In conclusion, our data showed that SAHA/bortezomib could synergistically induce killing of BL and LCL through counteracting the survival functions of EBNA3C, providing a strong basis for clinical testing of this drug combination in patients with EBV-associated lymphoproliferative diseases.
已证明，辛二酰苯胺异羟肟酸（SAHA）与硼替佐米的联合用药（SAHA/硼替佐米）可协同诱导杀伤淋巴母细胞系（LCL）以及III型或Wp限制潜伏期的伯基特淋巴瘤（BL），这两种疾病均表达EBNA3A、-3B和-3C蛋白。我们推测SAHA/硼替佐米可抵消EBNA3蛋白赋予的生存功能。我们测试了SAHA/硼替佐米对含有EBNA3A、-3B或-3C基因敲除的EBV且有或无各自回复性EBNA3基因的BL细胞系生存的影响。等效线图分析表明，与EBNA3C基因敲除细胞相比，SAHA/硼替佐米对EBNA3C回复性细胞具有显著更强的协同杀伤作用。在EBNA3A或-3B回复性细胞与其基因敲除配对细胞之间未观察到这种差异反应。有趣的是，EBNA3C基因敲除细胞表现出明显的G2/M期阻滞，而EBNA3C回复性细胞和LCL逃避了SAHA/硼替佐米诱导的G2/M期阻滞，并变得更易被诱导凋亡。同时，与EBNA3C基因敲除细胞相比，SAHA/硼替佐米在表达EBNA3C的细胞中诱导p21表达更强，但诱导M期诱导磷酸酶p-cdc25c的表达较弱。SAHA/硼替佐米对SCID小鼠中表达EBNA3C的异种移植物（EBNA3C回复性细胞和LCL）的生长抑制作用也大于对EBNA3C基因敲除异种移植物的抑制作用。总之，我们的数据表明，SAHA/硼替佐米可通过抵消EBNA3C的生存功能协同诱导杀伤BL和LCL，为在EBV相关淋巴增殖性疾病患者中对该药物联合进行临床试验提供了有力依据。
