Enzymatic Assemblies Disrupt the Membrane and Target Endoplasmic Reticulum for Selective Cancer Cell Death

Abstract

The endoplasmic reticulum (ER) is responsible for the synthesis and folding of a large number of proteins, as well as intracellular calcium regulation, lipid synthesis, and lipid transfer to other organelles, and is emerging as a target for cancer therapy. However, strategies for selectively targeting the ER of cancer cells are limited. Here we show that enzymatically generated crescent-shaped supramolecular assemblies of short peptides disrupt cell membranes and target ER for selective cancer cell death. As revealed by sedimentation assay, the assemblies interact with synthetic lipid membranes. Live cell imaging confirms that the assemblies impair membrane integrity, which is further supported by lactate dehydrogenase (LDH) assays. According to transmission electron microscopy (TEM), static light scattering (SLS), and critical micelle concentration (CMC), attaching an l-amino acid at the C-terminal of a d-tripeptide results in the crescent-shaped supramolecular assemblies. Structure-activity relationship suggests that the crescent-shaped morphology is critical for interacting with membranes and for controlling cell fate. Moreover, fluorescent imaging indicates that the assemblies accumulate on the ER. Time-dependent Western blot and ELISA indicate that the accumulation causes ER stress and subsequently activates the caspase signaling cascade for cell death. As an approach for in situ generating membrane binding scaffolds (i.e., the crescent-shaped supramolecular assemblies), this work promises a new way to disrupt the membrane and to target the ER for developing anticancer therapeutics.

Endoplasmic Reticulum: Target for Next‐Generation Cancer Therapy

“…In another study, Xu et al. developed new, enzymatically driven formation of crescent‐shaped supramolecular assemblies of short peptides capable of rupturing cell membranes and targeting the ER for anticancer activity . They confirmed the damage to membrane integrity by these assemblies through live‐cell imaging and lactate dehydrogenase (LDH) assays.…”

Assemblies of Peptides in a Complex Environment and their Applications

“…However, targeting the ER for cancer therapy is less explored due to the complex role of the ER in cell signaling . A recent study on the instructed assembly of peptides may lead to a new opportunity for the selective targeting of the ER in cancer therapy . Figure A shows the concept that instructed assembly generates self‐limited peptide assemblies to disrupt cell membranes and to target the ER for cancer therapy.…”

Too Crowded to Be Straight: Insights from Self-Assembly of Heterochiral Tripeptides

“…Although it is important to elucidate the molecular arrangements of heterochiral peptide hydrogelators in hydrogels, it is also worthwhile to explore the functions of the assemblies of heterochiral peptides. For example, a recent study 8 showed that a heterochiral tetrapeptide, after being generated by an enzymatic reaction, self-assembled to form crescent-shaped supramolecular assemblies. The crescent assemblies disrupted cell membranes and targeted the endoplasmic reticulum for selective cancer cell death.…”

“…These results, together with CD spectra and MD simulations, collectively illustrate that L-D-L heterochi-ral tripeptides differ from L-L-L homochiral tripeptides in their monomeric conformation, crystal structures, and gelation ability, thus providing correlations from microscopic to macroscopic properties. Because it remains a challenge to obtain the single-crystal structures of hydrogelators, the rare insight obtained from the comparison of CD spectra, MD simulation, and XRD crystal structures is particularly valuable for understanding the assemblies and functions of other hydrogelators made of short heterochiral peptides, which self-assemble to form bent nanofibers 7,8 or micelles. 9 Although it provides considerable insights for understanding the self-assembly of heterochiral and homochiral tripeptides, this study also raise many interesting questions.…”