Smart Nanosystem-Mediated Inhibition of Mitochondrial Respiration for Enhanced Phototherapy-Induced Antitumor Immunity

Abstract

Introduction:Here, based on oxygen-dependent photodynamic therapy (PDT) and oxygen-consumed oxidative phosphorylation of cancer tissues, we designed and developed a nanosystem (named CyI&Met-Liposome, LCM) to co-encapsulate the photosensitizer CyI and mitochondrial respiration inhibitor metformin (Met) as a PDT enhancer. Methods: We synthesized nanoliposomes encapsulating Met and CyI with excellent photodynamic/photothermal and anti-tumor immune properties using a thin film dispersion method. Confocal microscopy and flow cytometry were used to assess the cellular uptake, PDT, photothermal therapy (PTT) and immunogenicity of nanosystem in vitro. Finally, two tumor models in mice were constructed to investigate the tumor suppression and immunity in vivo. Results:The resulting nanosystem relieved hypoxia in tumor tissues, enhanced PDT efficiency, and amplified antitumor immunity induced by phototherapy. As a photosensitizer, CyI effectively killed the tumor by generating toxic singlet reactive oxygen species (ROS), while the addition of Met reduced oxygen consumption in tumor tissues, thereby evoking an immune response via oxygenboosted PDT. Both in vitro and in vivo results illustrated that LCM effectively restricted the respiration of tumor cells to reduce tumor hypoxia, thus providing continuous oxygen for enhanced CyI-mediated PDT. Furthermore, T cells were recruited and activated at high levels, providing a promising platform to eliminate the primary tumors and synchronously realize effective inhibition of distant tumors.

Engineering tumor-oxygenated nanomaterials: advancing photodynamic therapy for cancer treatment

“…Mitochondrial respiration is a crucial process that enables cells to generate energy in the form of adenosine triphosphate (ATP). Cancer cells heavily rely on this energy production pathway to sustain their rapid growth and proliferation ( Wang Q. et al, 2023 ; Zhao et al, 2023 ). Therefore, by selectively inhibiting mitochondrial respiration, it is possible to selectively target cancer cells while sparing healthy cells.…”