Modulating mitochondrial morphology enhances antitumor effect of 5-ALA-mediated photodynamic therapy both in vitro and in vivo

Antitumor Effect of Photodynamic Therapy/Sonodynamic Therapy/Sono-Photodynamic Therapy of Chlorin e6 and Other Applications

Chlorin e6 (Ce6) has been extensively researched and developed as an antitumor therapy. Ce6 is a highly effective photosensitizer and sonosensitizer with promising future applications in photodynamic therapy, dynamic acoustic therapy, and combined acoustic and light therapy for tumors. Ce6 is also being studied for other applications in fluorescence navigation, antibacterials, and plant growth regulation. Here we review the role and research status of Ce6 in tumor therapy and the problems and challenges of its clinical application. Other biomedical effects of Ce6 are also briefly discussed. Despite the difficulties in clinical application, Ce6 has significant advantages in photodynamic therapy (PDT)/sonodynamic therapy (SDT) against cancer and offers several possibilities in clinical utility.

Targeting mitochondria in cancer therapy: Insight into photodynamic and photothermal therapies

Mitochondria are critical multifunctional organelles in cells that generate power, produce reactive oxygen species, and regulate cell survival. Mitochondria that are dysfunctional are eliminated via mitophagy as a way to protect cells under moderate stress and physiological conditions. However, mitophagy is a double-edged sword and can trigger cell death under severe stresses. By targeting mitochondria, photodynamic (PD) and photothermal (PT) therapies may play a role in treating cancer. These therapeutic modalities alter mitochondrial membrane potential, thereby affecting respiratory chain function and generation of reactive oxygen species promotes signaling pathways for cell death. In this regard, PDT, PTT, various mitochondrion-targeting agents and therapeutic methods could have exploited the vital role of mitochondria as the doorway to regulated cell death. Targeted mitochondrial therapies would provide an excellent opportunity for effective mitochondrial injury and accurate tumor erosion. Herein, we summarize the recent progress on the roles of PD and PT treatments in regulating cancerous cell death in relation to mitochondrial targeting and the signaling pathways involved.

Efficient Synthesis of 2,3'-Spirobi (Indolin)-2'-Ones and Preliminary Evaluation of Their Damage to Mitochondria in HeLa Cells

A novel formal (4 + 1) annulation between N-(o-chloromethyl)aryl amides and 3-chlorooxindoles through in situ generated aza-ortho-QMs with 3-chlorooxindoles is reported for the synthesis of a series of 2,3′-spirobi (indolin)-2′-ones in high yields. Under structured illumination microscopy, compound 3a is found to change the mitochondrial morphology and induce mitophagy pathway, which might then trigger mitophagy in cancer cells.

Mito-Bomb: Targeting Mitochondria for Cancer Therapy

Cancer has been one of the most common life-threatening diseases for a long time. Traditional cancer therapies such as surgery, chemotherapy (CT), and radiotherapy (RT) have limited effects due to drug resistance, unsatisfactory treatment efficiency, and side effects. In recent years, photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) have been utilized for cancer treatment owing to their high selectivity, minor resistance, and minimal toxicity. Accumulating evidence has demonstrated that selective delivery of drugs to specific subcellular organelles can significantly enhance the efficiency of cancer therapy. Mitochondria-targeting therapeutic strategies are promising for cancer therapy, which is attributed to the essential role of mitochondria in the regulation of cancer cell apoptosis, metabolism, and more vulnerable to hyperthermia and oxidative damage. Herein, the rational design, functionalization, and applications of diverse mitochondria-targeting units, involving organic phosphine/sulfur salts, quaternary ammonium (QA) salts, peptides, transition-metal complexes, guanidinium or bisguanidinium, as well as mitochondria-targeting cancer therapies including PDT, PTT, CDT, and others are summarized. This review aims to furnish researchers with deep insights and hints in the design and applications of novel mitochondria-targeting agents for cancer therapy.

Co-delivery of chitosan nanoparticles of 5-aminolevulinic acid and shGBAS for improving photodynamic therapy efficacy in oral squamous cell carcinomas

BACKGROUND

The improvement of gene therapy provides hope for the treatment of cancer. However, malignant tumor is a multifactorial disease, which remains difficult to be cured with a single therapy. Our previous study reported that mitochondrial genes glioblastoma-amplified sequence (GBAS) plays a role in the development and treatment of oral squamous cell carcinoma (OSCC). The current study focused on building a mitochondrial-targeting drug co-delivery system for combined photodynamic therapy (PDT) and gene therapy.

METHODS

5-aminolevulinic acid (ALA) photosensitizer loaded chitosan (CS) nanoparticles were prepared using ionic crosslinking method, and further synthesized with the GBAS gene plasmid DNA (shGBAS) by electrostatic attraction. We detected the effects of PDT using the co-delivery system (CS-ALA-shGBAS) on cell proliferation and mitochondrial injury by MTT and reactive oxygen species (ROS) assays, respectively. Additionally, a oral cancer Xenograft model of nude mice was built to test its inhibitive effect on the cancerous growth in vivo.

RESULTS

A novel nanocomposite, CS-ALA-shGBAS, was found to be spherical structures and had good dispersion, stability and hypotoxicity. Gel retardation assay showed that CS-ALA nanoparticle could synthesize shGBAS at and above Nanoparticle/Plasmid ratios of 1/2. Excitingly, the co-delivery system was suitable for transfected cells and displayed a superior mitochondrially targeted killing effect on OSCC in vitro and in vivo.

CONCLUSION

Our study provides evidence that the chitosan-based co-delivery system of ALA-induced protoporphyrin IX (PpIX) photosensitizer and GBAS gene may be a novel mode of combined therapy for OSCC.

Cascade Reactions by Nitric Oxide and Hydrogen Radical for Anti-Hypoxia Photodynamic Therapy Using an Activatable Photosensitizer

Organelle-targeted activatable photosensitizers are attractive to improve the specificity and controllability of photodynamic therapy (PDT), however, they suffer from a big problem in the photoactivity under both normoxia and hypoxia due to the limited diversity of phototoxic species (mainly reactive oxygen species). Herein, by effectively photocaging a π-conjugated donor-acceptor (D-A) structure with an N-nitrosamine substituent, we established a unimolecular glutathione and light coactivatable photosensitizer, which achieved its high performance PDT effect by targeting mitochondria through both type I and type II (dual type) reactions as well as secondary radicals-participating reactions. Of peculiar interest, hydrogen radical (H^•) was detected by electron spin resonance technique. The generation pathway of H^• via reduction of proton and its role in type I reaction were discussed. We demonstrated that the synergistic effect of multiple reactive species originated from tandem cascade reactions comprising reduction of O₂ by H^• to form O₂^•-/HO₂^• and downstream reaction of O₂^•- with ^•NO to yield ONOO^-. With a relatively large two-photon absorption cross section for photoexcitation in the near-infrared region (166 ± 22 GM at 800 nm) and fluorogenic property, the new photosensitizing system is very promising for broad biomedical applications, particularly low-light dose PDT, in both normoxic and hypoxic environments.

Photodynamic therapy regulates fate of cancer stem cells through reactive oxygen species

Photodynamic therapy (PDT) is an effective and promising cancer treatment. PDT directly generates reactive oxygen species (ROS) through photochemical reactions. This oxygen-dependent exogenous ROS has anti-cancer stem cell (CSC) effect. In addition, PDT may also increase ROS production by altering metabolism, endoplasmic reticulum stress, or potential of mitochondrial membrane. It is known that the half-life of ROS in PDT is short, with high reactivity and limited diffusion distance. Therefore, the main targeting position of PDT is often the subcellular localization of photosensitizers, which is helpful for us to explain how PDT affects CSC characteristics, including differentiation, self-renewal, apoptosis, autophagy, and immunogenicity. Broadly speaking, excess ROS will damage the redox system and cause oxidative damage to molecules such as DNA, change mitochondrial permeability, activate unfolded protein response, autophagy, and CSC resting state. Therefore, understanding the molecular mechanism by which ROS affect CSCs is beneficial to improve the efficiency of PDT and prevent tumor recurrence and metastasis. In this article, we review the effects of two types of photochemical reactions on PDT, the metabolic processes, and the biological effects of ROS in different subcellular locations on CSCs.

Mathematical morphology-based imaging of gastrointestinal cancer cell motility and 5-aminolevulinic acid-induced fluorescence

The aim of this study was the quantitative evaluation of gastrointestinal cancer cell motility and 5-aminolevulinic acid (5-ALA)-induced fluorescence in vitro using mathematical morphology and structural analysis methods. The results of our study showed that MKN28 cells derived from the lymph node have the highest motility compared with AGS or HCT116 cells derived from primary tumors. Regions of single cells were characterized as most moving, and "tightly packed" cell colonies as nearly immobile. We determined the reduction of cell motility in late passage compared to early passage. Application of 5-ALA caused fluorescence in all investigated cells, and the fluorescence was different with regard to the cell type and application time. We observed higher fluorescence in MKN28 cells. Comprehensive image analysis did not reveal any statistically significant difference in fluorescence intensity between "tightly packed" cell regions, where nearly no motility was registered and loosely distributed cells, where the highest cell motility was registered. In conclusions, our study revealed that MKN28 cells derived from the lymph node have higher motility and 5-ALA-induced fluorescence than AGS or HCT116 derived from primary tumors. Moreover, image analysis based on a large amount of processed data is an important tool to study these tumor cell properties.

MMP-2-responsive gelatin nanoparticles for synergistic tumor therapy

Purpose: The aim of this study was to develop a new type of nanoparticle that enables concentrated drug release and synergistic therapy. Methods: To this end, we synthesized Ge-DOX-5-ALA/NPs, which can enter tumor tissue by the enhanced permeability and retention (EPR) effect and release drugs by utilizing matrix metalloproteinase-2 (MMP-2). Results: The Ge-DOX-5-ALA/NPs were synthesized by a single-phase coacervation method, and the hydrodynamic diameters of all nanoparticles were under 200 nm. The drug encapsulation and loading efficiency were 92%±1.13% and 6.02% ± 0.48%, respectively. Gelatin zymography was performed to detect the expression of MMP-2 in MCF-7 and Hs578Bst cells. The nanoparticle sensitivity to MMP-2 was examined by comparing the release behavior and cellular uptake in MCF-7 and Hs578Bst cells. In vitro cytotoxicity of the nanoparticles was measured by an MTT assay. An in vivo anticancer efficacy study in S180-bearing mice demonstrated that Ge-DOX-5-ALA/NPs provide a substantial curative effect. A pharmacokinetics experiment demonstrated that the nanoparticles have a sustained release effect. Conclusions: The MMP-2-triggered nanoparticles can transport drugs successfully into the tumor site and enable combined chemotherapy and photodynamic therapy.