发布: 2018年07月05日第8卷第13期 DOI: 10.21769/BioProtoc.2907 浏览次数: 8311
评审: HongLok LungTomas AparicioPornima Phatak
Abstract
One fundamental property of the TNR receptor (TNFR) family relates to how ‘signal quality’ (the extent of receptor ligation or cross-linking) influences the outcome of receptor ligation, for instance the induction of death in tumour cells. It is unequivocal that membrane-presented ligand (delivered to target cells via cell-surface presentation by co-culture with ligand-expressing third-party cells) induces a greater extent of carcinoma cell death in vitro in comparison to non-cross-linked agonists (agonistic antibodies and/or recombinant ligands). The CD40 receptor epitomises this fundamental property of TNF receptor-ligand interactions, as the extent of CD40 cross-linking dictates cell fate. Membrane-presented CD40 ligand (mCD40L), but not soluble agonists (e.g., agonistic anti-CD40 antibody), induces high level of pro-inflammatory cytokine secretion and causes extensive cell death (apoptosis) in malignant (but not normal) epithelial cells. In this article, we describe a co-culture system for the activation of CD40 by mCD40L and subsequent detection of various features of apoptosis (including cell membrane permeabilisation, DNA fragmentation, caspase activation) as well as detection of intracellular mediators of cell death (including adaptor proteins, pro-apoptotic kinases and reactive oxygen species, ROS).
Keywords: TNF receptors (TNFRs) (TNF受体 (TNFRs))Background
The role of the TNFRs and their ligands in regulating cell proliferation or death in lymphoid tissues as well as in epithelial (and particularly carcinoma) cells has been under extensive research, as their ability to induce cell death (mainly via apoptosis) represents a promising target for cancer therapy. Importantly, however, there is a clear difference in the ability of TNFR agonists to trigger cell death when presented in soluble versus membrane-bound form. Soluble agonists often demonstrate relatively low cytotoxic potency when administrated as a sole treatment, whereas membrane-presented ligands appear to be superior (Albarbar et al., 2015).
In this context, CD40 represents the most prominent TNFR family member. The receptor is expressed on a variety of epithelial cells and the effect of CD40 activation is exquisitely contextual (Young and Eliopoulos, 2004). Most importantly, the ability of CD40 to induce cytostasis or cell death (apoptosis) is highly dependent on the ‘quality’ of receptor engagement (degree of receptor cross-linking). Soluble CD40 agonists (recombinant soluble CD40L or agonistic antibody) are only cytostatic or weakly pro-apoptotic and only rendered pro-apoptotic by pharmacological intervention (Bugajska et al., 2002). By contrast, membrane-presented CD40L (mCD40L) is highly pro-apoptotic and induces extensive apoptosis in carcinoma cells, when presented to target carcinoma cells on the surface of third-party cells (Georgopoulos et al., 2006 and 2007) or by mCD40L-expressing, naturally-activated immunocytes (Hill et al., 2008).
The ability of mCD40L (but not soluble agonists) to efficiently kill malignant cells, and in a tumour cell-specific fashion, reflects the two most remarkable properties of the CD40-mCD40L dyad and our recent studies have deciphered these two fundamental properties of CD40. We utilised a co-culture system that involved culture of target, carcinoma (or normal) cells with growth-arrested, third-party, effector cells engineered to express the CD40L on their surface, in order to achieve presentation of mCD40L. This allowed us to study the ability of mCD40L to induce a number of different morphological and biochemical features of apoptosis, as well as define the intracellular mediators of cell death (Dunnill et al., 2017). Here, we provide a detailed protocol for the preparation of the co-culture system for mCD40L delivery to epithelial target cells (in comparison to soluble agonist, i.e., agonistic anti-CD40 antibody) and methodologies to assess mCD40L-induced apoptosis and detection of its intracellular mediators.
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文章信息
版权信息
© 2018 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Ibraheem, K., Dunnill, C. J., Ioannou, M., Mohamed, A., Albarbar, B. and Georgopoulos, N. T. (2018). An in vitro Co-culture System for the Activation of CD40 by Membrane-presented CD40 Ligand versus Soluble Agonist. Bio-protocol 8(13): e2907. DOI: 10.21769/BioProtoc.2907.
分类
癌症生物学 > 细胞死亡 > 细胞生物学试验
细胞生物学 > 细胞分离和培养 > 共培养
细胞生物学 > 细胞信号传导 > 胞内信号传导
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