Qiu X, Klausen C, Cheng J-C, Leung P C K
Department of Obstetrics and Gynaecology, Child & Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada.
Cell Death Dis. 2015 Aug 27;6(8):e1864. doi: 10.1038/cddis.2015.229.
Ovarian high-grade serous carcinomas (HGSCs) and invasive low-grade serous carcinomas (LGSCs) are considered to be distinct entities. In particular, LGSCs are thought to arise from non-invasive serous borderline ovarian tumors (SBOTs) and show poor responsiveness to conventional chemotherapy. The pro-apoptotic effects of CD40 ligand (CD40L) have been demonstrated in HGSC, though the underlying mechanisms are not fully understood. Conversely, the therapeutic potential of the CD40L-CD40 system has yet to be evaluated in LGSC. We now show that CD40 protein is focally expressed on tumor cells in two of five primary LGSCs compared with no expression in eight primary SBOTs. Treatment with CD40L or agonistic CD40 antibody decreased the viability of LGSC-derived MPSC1 and VOA1312 cells, but not SBOT3.1 cells. Small interfering RNA (siRNA) targeting CD40 was used to show that it is required for these reductions in cell viability. CD40L treatment increased cleaved caspase-3 levels in MPSC1 cells though, surprisingly, neither pan-caspase inhibitor nor caspase-3 siRNA reversed or even attenuated CD40L-induced cell death. In addition, CD40-induced cell death was not affected by knockdown of the mitochondrial proteins apoptosis-inducing factor (AIF) and endonuclease G (EndoG). Interestingly, CD40L-induced cell death was blocked by necrostatin-1, an inhibitor of receptor-interacting protein 1 (RIP1), and attenuated by inhibitors of RIP3 (GSK'872) or MLKL (mixed lineage kinase domain-like; necrosulfonamide). Our results indicate that the upregulation of CD40 may be relatively common in LGSC and that CD40 activation induces RIP1-dependent, necroptosis-like cell death in LGSC cells.
卵巢高级别浆液性癌（HGSCs）和侵袭性低级别浆液性癌（LGSCs）被认为是不同的实体。特别是，LGSCs被认为起源于非侵袭性浆液性交界性卵巢肿瘤（SBOTs），并且对传统化疗反应不佳。尽管其潜在机制尚未完全了解，但CD40配体（CD40L）的促凋亡作用已在HGSC中得到证实。相反，CD40L-CD40系统在LGSC中的治疗潜力尚未得到评估。我们现在表明，与八个原发性SBOTs中无表达相比，五个原发性LGSCs中有两个的肿瘤细胞上局部表达CD40蛋白。用CD40L或激动性CD40抗体处理可降低LGSC来源的MPSC1和VOA1312细胞的活力，但对SBOT3.1细胞无效。靶向CD40的小干扰RNA（siRNA）用于表明细胞活力的这些降低需要CD40。CD40L处理增加了MPSC1细胞中裂解的半胱天冬酶-3水平，然而，令人惊讶的是，泛半胱天冬酶抑制剂和半胱天冬酶-3 siRNA均未逆转甚至减弱CD40L诱导的细胞死亡。此外，CD40诱导的细胞死亡不受线粒体蛋白凋亡诱导因子（AIF）和核酸内切酶G（EndoG）敲低的影响。有趣的是，CD40L诱导的细胞死亡被受体相互作用蛋白1（RIP1）的抑制剂坏死抑制素-1阻断，并被RIP-3（GSK'872）或MLKL（混合谱系激酶结构域样；坏死磺酰胺）的抑制剂减弱。我们的结果表明，CD40的上调在LGSC中可能相对常见，并且CD40激活在LGSC细胞中诱导RIP1依赖性、坏死性凋亡样细胞死亡。
