Delivery of cell membrane impermeable peptides into living cells by using head-to-tail cyclized mitochondria-penetrating peptides

Antimicrobial Peptides Mediate Apoptosis by Changing Mitochondrial Membrane Permeability

Changes in mitochondrial membrane permeability are closely associated with mitochondria-mediated apoptosis. Antimicrobial peptides (AMPs), which have been found to enter cells to exert physiological effects, cause damage to the mitochondria. This paper reviews the molecular mechanisms of AMP-mediated apoptosis by changing the permeability of the mitochondrial membrane through three pathways: the outer mitochondrial membrane (OMM), inner mitochondrial membrane (IMM), and mitochondrial permeability transition pore (MPTP). The roles of AMPs in inducing changes in membrane permeability and apoptosis are also discussed. Combined with recent research results, the possible application prospects of AMPs are proposed to provide a theoretical reference for the development of AMPs as therapeutic agents for human diseases.

Different Approaches to Cyclize a Cell-Penetrating Peptide and to Tether Bioactive Payloads

Cell-penetrating peptides (CPPs) are versatile tools to deliver various molecules into different cell types. The majority of CPPs are usually represented by linear structures, but numerous recent studies demonstrated cyclization to be an effective strategy leading to favorable biological activities. Here we describe two different methods for the side chain and backbone cyclization of CPPs . Furthermore, we highlight straightforward procedures for the covalent coupling of fluorophores or cytotoxic payloads.

Light-Induced Reactive Oxygen Species (ROS) Generator for Tumor Therapy through an ROS Burst in Mitochondria and AKT-Inactivation-Induced Apoptosis

Mitochondria are identified as a valuable target for cancer therapy owing to their primary function in energy supply and cellular signal regulation. Mitochondria in tumor cells are depicted by excess reactive oxygen species (ROS), which lead to numerous detrimental results. Hence, mitochondria-targeting ROS-associated therapy is an optional therapeutic strategy for cancer. In this contribution, a light-induced ROS generator (TBTP) is developed for evaluation of the efficacy of mitochondria-targeting ROS-associated therapy and investigation of the mechanism underlying mitochondrial-injure-mediated therapy of tumors. TBTP serves as an efficient ROS generator with low cytotoxicity, favorable biocompatibility, excellent photostability, mitochondria-targeted properties, and NIR emission. In vivo and in vitro experiments reveal that TBTP exhibits effective anticancer potential. ROS generated from TBTP could destroy the integrity of mitochondria, downregulate ATP, decrease the mitochondrial membrane potential, secrete Cyt-c into cytoplasm, activate Caspase-3/9, and induce cell apoptosis. Moreover, RNA-seq analysis highlights that an ROS burst in mitochondria can kill tumor cells via inhibition of the AKT pathway. All these results prove that mitochondrial-targeted ROS-associated therapy hold great potential in cancer therapy.

Improvement on Permeability of Cyclic Peptide/Peptidomimetic: Backbone N-Methylation as A Useful Tool

Peptides have a three-dimensional configuration that can adopt particular conformations for binding to proteins, which are well suited to interact with larger contact surface areas on target proteins. However, low cell permeability is a major challenge in the development of peptide-related drugs. In recent years, backbone N-methylation has been a useful tool for manipulating the permeability of cyclic peptides/peptidomimetics. Backbone N-methylation permits the adjustment of molecule’s conformational space. Several pathways are involved in the drug absorption pathway; the relative importance of each N-methylation to total permeation is likely to differ with intrinsic properties of cyclic peptide/peptidomimetic. Recent studies on the permeability of cyclic peptides/peptidomimetics using the backbone N-methylation strategy and synthetic methodologies will be presented in this review.

Mitochondria and Endoplastic Reticulum Targeting Strategy for Enhanced Phototherapy

To ensure improved efficacy and minimized toxicity of therapeutic molecules, it is generally accepted that specifically delivering them to the subcellular site of their action will be attractive. Phototherapy has received considerable attention because of its noninvasiveness, high temporal-spatial resolution, and minimal drug resistance. As important functional organelles in cells, mitochondria and endoplasmic reticulum (ER) participate in fundamental cellular processes, which make them much more sensitive to reactive oxygen species (ROS) and hyperthermia. Thus, mitochondria- or ER-targeted phototherapy will be rational strategies for synergetic cancer therapy. In this review, we focus on the latest advances in molecules and nanomaterials currently used for mitochondria- and ER-targeted phototherapy.