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The Role of Nanoparticles in Cancer Therapy through Apoptosis Induction
Published in Hala Gali-Muhtasib, Racha Chouaib, Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
Marveh Rahmati, Saeid Amanpour, Hadiseh Mohammadpour
TNFα is induced by cytokines which are released by inflammatory cells and particularly activated macrophages. TNFα is the main extrinsic stimulus of extrinsic apoptosis. TNFR1 and TNFR2 are two receptors for TNFα in most cells. After the binding of TNFα to TNFR1, CASP-8 is activated in DICS complex, which contains the intermediate membrane proteins TNF receptor-associated death domain (TRADD). TRADD subsequently recruits other effector proteins such as FADD/MORT1 (FAS-Associated Death Domain Protein) into DISC complex. Regardless of apoptosis, the TNFα-TNFR pathway can also indirectly activate some of the transcription factors involved in cell survival and inflammatory responses [34]. In response to TNF induction, the transcription factor NF-κB and MAP kinases, including ERK, p38, and JNK, are activated in most cell types. Apoptosis or necrosis could also be initiated.
Mechanisms of Nanotoxicity to Cells, Animals, and Humans
Published in Vineet Kumar, Nandita Dasgupta, Shivendu Ranjan, Nanotoxicology, 2018
Belinda Wong Shu Ee, Puja Khanna, Ng Cheng Teng, Baeg Gyeong Hun
The extrinsic pathway, also known as the death receptor pathway, involves transmembrane receptor-mediated interactions. The name is derived from the role of death receptors, which are a part of the TNF receptor gene superfamily in this pathway. The cytoplasmic death domain is made up of around 80 amino acid residues and plays a critical role in transmitting death signals from cellular surface to intracellular signaling pathways. A few of the ligands that are best characterized in this pathway along with their receptors are FasL/FasR and TNF-α/TNFR1 (Elmore 2007). Fas ligand (FasL) binds to Fas receptor (FasR) which leads to the interaction of adaptor protein Fas-associated death domain protein (FADD) with procaspase-8. Thus, the death-inducing signaling complex (DISC) composed of FasR, FADD, and procaspase-8 is formed (Wajant 2002). Similarly, TNF-α binds to TNF receptor 1 (TNFR1) which promotes the binding of adaptor protein TNFR1-associated death domain protein (TRADD) to the death domain of TNFR1 (Hsu et al. 1995). Procaspase-8 is cleaved into its active form caspase-8 and sets the execution pathway in motion (Elmore 2007).
Pro- and Anti-Inflammatory Cytokine Signaling within 3D Tissue Models
Published in Karen J.L. Burg, Didier Dréau, Timothy Burg, Engineering 3D Tissue Test Systems, 2017
Stephen L. Rego, Tian McCann, Didier Dréau
TNFα (also referred to as TNF as TNFβ is now commonly denoted as lymphotoxin) resides at the apex of inflammatory signaling (Locksley et al. 2001). TNF is secreted primarily by monocytes; however, it is also expressed by a number of other immune and nonimmune cell types (Dreau et al. 2000). Responses elicited by TNF include apoptosis, cachexia, inflammation, and inhibition of tumorigenesis (Aggarwal et al. 2012). TNF acts by binding to one of its two cognate receptors; TNF receptor 1 (TNFR1) and TNFR2, where both lead to activation of downstream signaling cascades (outlined in Section 2.3) (Henkler et al. 2003; Wajant et al. 2003).
Silver nanoparticles reduce the apoptosis induced by tumor necrosis factor-α
Published in Science and Technology of Advanced Materials, 2018
Alaa Fehaid, Akiyoshi Taniguchi
TNFR1 is a major receptor for TNFα, mediates apoptosis, and functions as a regulator of inflammation [21]. Our cellular uptake assay results indicated that TNFα increases the cellular uptake of AgNPs. We demonstrated the localization of TNFR1 by immunofluorescence staining using confocal microscopy. The results revealed that TNFR1 is homogenously distributed on the cell membrane of control cells, as shown in Figure 5(a). In contrast, TNFR1 was slightly aggregated and scattered over the entire cell membrane of cells exposed to TNFα (20 ng/mL), as shown in Figure 5(b), whereas in cells exposed to both TNFα (20 ng/mL) and AgNPs (5 µg/mL), TNFR1 was localized inside the cells and very few receptors were scattered on the cell membrane, as shown in Figure 5(c). The results indicated that AgNPs reduced the expression level of cell surface TNFR1 and suggested that this reduction in surface TNFR1 reduced the cellular response to TNFα, resulting in an anti-apoptotic effect.