Hyperthermia restores apoptosis induced by death receptors through aggregation-induced c-FLIP cytosolic depletion

Abstract

TRAIL is involved in immune tumor surveillance and is considered a promising anti-cancer agent owing to its limited side effects on healthy cells. However, some cancer cells display resistance, or become resistant to TRAIL-induced cell death. Hyperthermia can enhance sensitivity to TRAIL-induced cell death in various resistant cancer cell lines, including lung, breast, colon or prostate carcinomas. Mild heat shock treatment has been proposed to restore Fas ligand or TRAIL-induced apoptosis through c-FLIP degradation or the mitochondrial pathway. We demonstrate here that neither the mitochondria nor c-FLIP degradation are required for TRAIL-induced cell death restoration during hyperthermia. Our data provide evidence that insolubilization of c-FLIP, alone, is sufficient to enhance apoptosis induced by death receptors. Hyperthermia induced c-FLIP depletion from the cytosolic fraction, without apparent degradation, thereby preventing c-FLIP recruitment to the TRAIL DISC and allowing efficient caspase-8 cleavage and apoptosis. Hyperthermia-induced c-FLIP depletion was independent of c-FLIP DED2 FL chain assembly motif or ubiquitination-mediated c-FLIP degradation, as assessed using c-FLIP point mutants on lysine 167 and 195 or threonine 166, a phosphorylation site known to regulate ubiquitination of c-FLIP. Rather, c-FLIP depletion was associated with aggregation, because addition of glycerol not only prevented the loss of c-FLIP from the cytosol but also enabled c-FLIP recruitment within the TRAIL DISC, thus inhibiting TRAIL-induced apoptosis during hyperthermia. Altogether our results demonstrate that c-FLIP is a thermosensitive protein whose targeting by hyperthermia allows restoration of apoptosis induced by TNF ligands, including TRAIL. Our findings suggest that combining TRAIL agonists with whole-body or localized hyperthermia may be an interesting approach in cancer therapy.

Coupling tumor necrosis factor‐related apoptosis‐inducing ligand to iron oxide nanoparticles increases its apoptotic activity on HCT116 and HepG2 malignant cells: effect of magnetic core size

“…We have already established the magnetocalorimetric properties of coated (Hai et al, ) and uncoated (Hanini et al, ) polyol‐made iron oxide NPs and their ability to induce malignant cell apoptosis by hyperthermia, opening up synergetic therapeutic opportunities. Indeed, a local rise of temperature under an applied AC magnetic field can sensitize tumor cells to TRAIL‐induced apoptosis (Morle et al, ; Moulin and Arrigo, ; Moulin et al, ; Yoo et al, ) as it can compensate the lack of efficiency of TRAIL in certain resistant cells (Song et al, ).…”

Metabolic reprogramming of glioblastoma cells by L-asparaginase sensitizes for apoptosis in vitro and in vivo

“…Given that L-asparaginase affects protein synthesis, it is likely that the level of proteins with a short half-life, such as Mcl-1 [28, 29], c-FLIP [30, 31] or survivin [32] are decreased by L-asparaginase which in turn increases TRAIL-mediated apoptosis. Consistently, our findings showed that L-asparaginase broadly sensitized glioblastoma cells to TRAIL-mediated apoptosis in a synergistic fashion.…”

Enhanced DR5 binding capacity of nanovectorized TRAIL compared to its cytotoxic version by affinity chromatography and molecular docking studies

“…When bound to specific DR4 or DR5, TRAIL homotrimers induce multimerization of these receptors, allowing subsequent recruitment of intracellular proteins through homotypic interactions, thanks to a short domain composed of 80 amino acids called the Death Domain (DD). This cascade of events lead to the formation of the Death‐Inducing Signaling Complex (DISC), at the membrane level, a macromolecular complex, the composition of which determines the fate of the cell (Morlé et al, ), undergoing or not apoptosis (J.L. ; Bodmer et al, 2000; LeBlanc et al, ; Shirley et al, ).…”