Inhibition of Fas Receptor Endocytosis Sensitizes Cancer Cells to Fas-induced Apoptosis

Abstract

Fas (CD95/APO-1) is a transmembrane death receptor that transduces apoptotic signals upon binding to its ligand and assembling into a death-inducing signaling complex (DISC) (1, 2). Intracellular trafficking of Fas receptors, including recycling from endosomes to the plasma membrane, plays a vital role in ligand-induced assembly of DISC (3, 4). Although Fas is highly expressed in tumor cells (5, 6), insufficient expression of these receptors on the cell surface makes cancer cells insensitive to the Fas-induced apoptosis (4, 7-9). Here we show that inhibition of endocytosis increases the formation of Fas microaggregates on the plasma membrane and sensitizes cancer cells to Fas-induced apoptosis. We have identified a clinically used vasodilator, Fasudil, that slows down endocytosis by increasing plasma membrane tension. Fasudil enhanced apoptosis in cancerous cells when combined with exogenous soluble Fas ligand (FasL), whereas the synergistic effect was substantially weaker in nonmalignant cells. Additionally, the FasL and Fasudil combination prevented glioblastoma cell growth in embryonic stem cell-derived brain organoids and induced tumor regression in a xenograft U87 tumor model in nude mice. Our results demonstrate that FasL treatment has strong potential as an apoptosis-directed cancer therapy when the formation of Fas microaggregates is augmented by slowing down endocytosis dynamics.

Tension-induced adhesion mode switching: the interplay between focal adhesions and clathrin-containing adhesion complexes

“…We recently reported that, fasudil, a Rho kinase inhibitor, increases membrane tension and cortical actins. Conversely, leptin, which increases stress fibers-based actomyosin contractility, reduces membrane tension (Figure 3c) (108). We further verified these results by comparing the phosphorylated ERM (Ezrin, radixin, moesin) proteins in these cells.…”

“…Beyond molecular interventions in CME, manipulating the mechanical properties of cancer cell membranes has shown potential in reducing malignancy (152,162–164). For instance, it was shown that increasing membrane tension prevented endocytosis of death receptors, thereby enhancing sensitivity of cancer cells to immune cell-mediated destruction (108,165). Therefore, increasing membrane tension might not only sensitize cancer cells to apoptosis but also inhibit clathrin pit and FA formation, further impeding cancer progression.…”