Stimuli-responsive nano vehicle enhances cancer immunotherapy by coordinating mitochondria-targeted immunogenic cell death and PD-L1 blockade

Induction of immunogenic cell death promotes antitumor immunity against cancer. However, majority of clinically-approved drugs are unable to elicit sufficient ICD. Here, our study revealed that mitochondria-targeted delivery of doxorubicin (DOX) massively amplified ICD via substantial generation of reactive oxygen species (ROS) after mitochondrial damage. The underlying mechanism behind increased ICD was further demonstrated to be ascribed to two pathways: (1) ROS elevated endoplasmic reticulum (ER) stress, leading to surface exposure of calreticulin; (2) ROS promoted release of various mitochondria-associated damage molecules including mitochondrial transcription factor A. Nevertheless, adaptive upregulation of PD-L1 was found after such ICD-inducing treatment. To overcome such immunosuppressive feedback, we developed a tumor stimuli-responsive nano vehicle to simultaneously exert mitochondrial targeted ICD induction and PD-L1 blockade. The nano vehicle was self-assembled from ICD-inducing copolymer and PD-L1 blocking copolymer, and possessed long-circulating property which contributed to better tumor accumulation and mitochondrial targeting. As a result, the nano vehicle remarkably activated antitumor immune responses and exhibited robust antitumor efficacy in both immunogenic and non-immunogenic tumor mouse models.

Multi-responsive nanotheranostics with enhanced tumor penetration and oxygen self-producing capacities for multimodal synergistic cancer therapy

Incorporation of multiple functions into one nanoplatform can improve cancer diagnostic efficacy and enhance anti-cancer outcomes. Here, we constructed doxorubicin (DOX)-loaded silk fibroin-based nanoparticles (NPs) with surface functionalization by photosensitizer (N770). The obtained nanotheranostics (N770-DOX@NPs) had desirable particle size (157 nm) and negative surface charge (-25 mV). These NPs presented excellent oxygen-generating capacity and responded to a quadruple of stimuli (acidic solution, reactive oxygen species, glutathione, and hyperthermia). Surface functionalization of DOX@NPs with N770 could endow them with active internalization by cancerous cell lines, but not by normal cells. Furthermore, the intracellular NPs were found to be preferentially retained in mitochondria, which were also efficient for near-infrared (NIR) fluorescence imaging, photothermal imaging, and photoacoustic imaging. Meanwhile, DOX could spontaneously accumulate in the nucleus. Importantly, a mouse test group treated with N770-DOX@NPs plus NIR irradiation achieved the best tumor retardation effect among all treatment groups based on tumor-bearing mouse models and a patient-derived xenograft model, demonstrating the unprecedented therapeutic effects of trimodal imaging-guided mitochondrial phototherapy (photothermal therapy and photodynamic therapy) and chemotherapy. Therefore, the present study brings new insight into the exploitation of an easy-to-use, versatile, and robust nanoplatform for programmable targeting, imaging, and applying synergistic therapy to tumors.

Mitochondrial DNA Targeting Therapies / 中国生物化学与分子生物学报

The mitochondrion is a particularly important organelle in eukaryotic cells. It contains its own genetic material and is coined as “the powerhouse of cells”. Mitochondria are involved in many cellular progresses such as cell signaling and metabolic homeostasis. Its dysfunction is linked to various human diseases, including cancer, neurodegenerative diseases, and diabetes. Mitochondrion has a unique DNA, a small size with 16 569 bp circular genome, encoding only 37 genes, which are key components of the electron transport chain (ETC) and translational machinery. Furthermore, the mutations of mitochondrion DNA correlate with some inherited disease such as Leber’ s hereditary optic neuropathy (LHON) and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS). There are very few treatments to fully cure these diseases. As a result, researchers are interested in developing a wide range of methods to understand mitochondrial functions. In this review, we mainly focus on works in targeting mitochondrial DNA, including drug modification, material delivery and gene editing.

Mitochondrial targeting function of norcantharidin TPP-PEG-PCL nanomicelles promotes apoptosis of liver tumor cells / 中草药

Objective: To prepare norcantharidin TPP-PEG-PCL nanomicelles and study its release in vitro, intracellular transport and promoting effect on hepatoma cell apoptosis. Methods: Thin film hydration method was used to prepare norcantharidin TPP-PEG-PCL nanomicelles, and the particle size, electric potential and microscopic electron microscopy morphological analysis were measured. At the same time, the nanomicelles were evaluated for stability, in vitro release, pharmacokinetics and critical micelle concentration. Coumarin-6 was used as a fluorescent probe to evaluate the uptake of TPP-PEG-PCL nanomicelles in liver tumor cells, lysosomal escape and mitochondrial targeting function; Under the same dosage conditions, the effect of norcantharidin TPP-PEG-PCL nanomicelles on promoting apoptosis of liver tumor cells was evaluated. Results: The cantharidin TPP-PEG-PCL nanomicelles had a particle size of (16.8 ± 0.2) nm, a Zeta potential of (14.3 ± 0.2) mV, and transmission electron microscopy images showed that nanomicelles had a regular spherical shape. The fluorescence test results showed that TPP-PEG-PCL nanomicelles can promote the cellular uptake of drugs, escape lysosomal capture, and finally target aggregation at the mitochondrial site; Cell survival rate and Hoechst staining results showed that cantharidin TPP-PEG-PCL nanomicelles had a good effect on promoting apoptosis of liver tumor cells. Norcantharidin TPP-PEG-PCL nanomicelles can significantly reduce mitochondrial membrane potential, increase intracellular ROS levels, increase pro-apoptotic protein Bcl-2, and reduce resistance. The expression of apoptotic proteins Bax and these pro-apoptotic related experimental results are significantly better than those of norcantharidin PEG-PCL nanomicelles and norcantharidin, which have statistical significance. Conclusion: Norcantharidin TPP-PEG-PCL nanomicelles have good liver tumor cell mitochondrial targeting and promote tumor cell apoptosis, and it is a potentially effective drug delivery system for targeting tumor cell mitochondria.

Optimization of pH response and mitochondrial targeting bifunctional hyperoside liposomes by central composite design response surface methodology and its in vitro evaluation / 中草药

Objective: To optimize preparation of mitochondrial targeting hyperoside liposomes (DLD/Hyp-Lip), and study its stability in fetal bovine serum, in vitro release behavior and mitochondrial targeting. Methods: DLD/Hyp-lip was prepared by film dispersion method. Single factor experiment was carried out with entrapment efficiency and drug loading as indexes to investigate the effects of the ratio of phospholipids to hyperoside (Hyp) and DSPE-PEG (distearoyl phosphoethanolamine-polyethylene glycol) to DLD on DLD/Hyp-Lip. The formulation of DLD/Hyp-Lip was further optimized by central composite design response surface methodology. The appearance, size and potential of liposomes were observed by transmission electron microscope and particle size analyzer. The stability and drug release rate of liposomes in fetal bovine serum were evaluated by serum stability test and in vitro drug release test. The drug delivery system was evaluated by mitochondrial targeting. Results: The optimal formula of DLD/ Hyp-Lip was as follows: the ratio of total phospholipids to hyperoside was 12.50:1, the ratio of total phospholipids to cholesterol was 6.00:1, and the dosage ratio of DSPE-PEG to DLD was 3:5, the encapsulation efficiency was (95.57 ± 0.56) %, the drug loading was (8.55 ± 0.57) %. The prepared liposomes had good appearance, the particle size of the lip was (124.9 ± 3.4) nm, and the potential was (-6.2 ± 1.9) mV. It was stable in fetal bovine serum and accumulated in vitro release medium for 24 h. Mitochondrial targeting experiments showed that DLD/Hyp-Lip could promote the accumulation of drugs in the mitochondria. Conclusion: This method is simple and convenient, and can accurately and effectively optimize the preparation process of DLD/Hyp-Lip. The prepared DLD/Hyp-Lip has high encapsulation efficiency, small particle size, uniform distribution and good sustained-release effect, which lays the foundation for further in vivo research of DLD/Hyp-Lip. DLD/Hyp-Lip with hyperoside has good mitochondrial targeting of liver cancer cells and is a potentially efficient mitochondrial targeted drug delivery system for liver cancer cells.

Preparation of curcumin TPP-PEG-PE nanomicelles with mitochondrial targeting and lysosomal escape functions and its effect on promoting breast cancer cell apoptosis / 中国中药杂志

Orthogonal experiments were used to optimize the process parameters of curcumin TPP-PEG-PCL nanomicelles; the particle size, electric potential and morphology under the electron microscope were systematically detected for the curcumin TPP-PEG-PCL nanomicelles; and the stability and in vitro release of the curcumin TPP-PEG-PCL nanomicelles were investigated. With DID fluorescent dye as the fluorescent probe, flow cytometry was used to study the uptake of nanomicelles by breast cancer cells, and laser confocal microscopy was used to study the mitochondrial targeting and lysosomal escape functions of nanomicelles. Under the same dosage conditions, the effect of curcumin TPP-PEG-PCL nanomicelles on promoting the apoptosis of breast cancer cells was evaluated. The optimal particle size of curcumin TPP-PEG-PCL nanomicelle was(17.3±0.3) nm, and the Zeta potential was(14.6±2.6) mV in orthogonal test. Under such conditions, the micelle appeared as regular spheres under the transmission electron microscope. Fluorescence test results showed that TPP-PEG-PCL nanomicelles can promote drug uptake by tumor cells, escape from lysosomal phagocytosis, and target the mitochondria. The cell survival rate and Hoechst staining positive test results showed that curcumin TPP-PEG-PCL nanomicelles had a good effect on promoting apoptosis of breast cancer cells. The curcumin TPP-PEG-PCL micelles can significantly reduce the mitochondrial membrane potential of breast cancer cells, increase the release of cytochrome C, significantly increase the expression of pro-apoptotic protein Bcl-2 and reduce the expression of anti-apoptotic Bax protein. These test results were significantly better than those of curcumin PEG-PCL nanomicelles and curcumin, with statistically significant differences. The results revealed that curcumin TPP-PEG-PCL nanomicelles can well target breast cancer cell mitochondria and escape from the lysosomal capture, thereby enhancing the drug's role in promoting tumor cell apoptosis.

Construction of lentivirus-mediated mito-OGG1 gene overexpression and OGG1 gene knockdown model in 661W cells / 中华实验眼科杂志

Objective To construct and authenticate the lentiviral-mediated overexpression of mouse mitochondrial-targeted-8-oxoguanine DNA-glycosylase 1 (mito-OGG1) gene and the lentiviral-mediated short hairpin RNA (shRNA) down-regulation of OGG1 gene expression model in 661W cells.Methods Constructed the target plasmids,including pLenti-EF1a-EGFP-P2A-Puro-CMV-Mito-OGG1-3Flag (pLenti-OGG1-GFP) and pLKD-CMV-G&PR-U6-shRNA (pLKD-shRNA).293T cells were used to obtain green fluorescent protein (GFP)-tagged lentiviral vector of interest by using a second generation lentivirus packaging system.293T cells were also used for the virus titer estimation.The multiplicity of infection (MOI) of 661W cells was detected by fluorescence microscopy.A stable transfected cell line was screened by puromycin.Immunofluorescence was used to detect transfection efficiency and cytochrome C oxidase Ⅳ (COXⅣ)-OGG1 co-localization.OGG1 mRNA and protein expression levels were detected by real-time qantitative PCR (QPCR) and Western blot.Results Sequencing results showed that the inserted sequence in the over-expression plasmid was consistent with the mouse OGG1 (NM_010957.4) gene sequence in the gene library.The original lentiviral titer after packaging and purification was between 2.0× 107to 6.0× 107 TU/ml.The optimal MOI of 661W cells was 40,and puromycin with a concentration of 4.0 μg/ml successfully screened stable transformation.The transfection efficiency was up to 100％ after screening.Immunofluorescence demonstrated successful co-localization of OGG1 and COXⅣ.The relative expression levels of OGG1 mRNA in the blank control group,OGG1 group,overexpression control group,shRNA group and low expression control group were 1.000±0.000,41.581±12.206,0.888±0.056,0.239±0.121 and 1.081±0.083,and the relative expression levels of OGG1 protein were 1.029±0.153,1.657 ± 0.237,0.752 ± 0.143,0.471 ± 0.149 and 1.036 ± 0.185,respectively,with significant differences between them (F=44.654,30.948;both at P＜0.05),the relative expression levels of OGG1 mRNA and protein in the OGG1 group were significantly higher than those in the overexpression control group,the relative expression levels of OGG1 mRNA and protein in the shRNA group were significantly lower than those in the lower expression control group,with significant differences between them (all at P＜0.05).Conclusions The mitoOGG1 overexpression and OGG1 knockdown models of 661W cells are successfully constructed,which provides the preliminary experimental basis for follow-up study.

Overcoming chemotherapy resistance simultaneous drug-efflux circumvention and mitochondrial targeting

Multidrug resistance (MDR) has been considered as a huge challenge to the effective chemotherapy. Therefore, it is necessary to develop new strategies to effectively overcome MDR. Here, based on the previous research of -(2-hydroxypropyl)methacrylamide (HPMA) polymer-drug conjugates, we designed an effective system that combined drug-efflux circumvention and mitochondria targeting of anticancer drug doxorubicin (Dox). Briefly, Dox was modified with mitochondrial membrane penetrating peptide (MPP) and then attached to (HPMA) copolymers (P-M-Dox). Our study showed that macromolecular HPMA copolymers successfully bypassed drug efflux pumps and escorted Dox into resistant MCF-7/ADR cells endocytic pathway. Subsequently, the mitochondria accumulation of drugs was significantly enhanced with 11.6-fold increase by MPP modification. The excellent mitochondria targeting then resulted in significant enhancement of reactive oxygen species (ROS) as well as reduction of adenosine triphosphate (ATP) production, which could further inhibit drug efflux and resistant cancer cell growth. By reversing Dox resistance, P-M-Dox achieved much better suppression in the growth of 3D MCF-7/ADR tumor spheroids compared with free Dox. Hence, our study provides a promising approach to treat drug-resistant cancer through simultaneous drug efflux circumvention and direct mitochondria delivery.

In vitro evaluation of mitochondrial-targeted taxol TPP-PEG-PE nanomicelles and promotion of tumor cell apoptosis / 中草药

Objective To prepare taxol TPP-PEG-PE nanomicelles and study its in vitro release behavior, mitochondrial targeting and pro-apoptosis of A549 lung cancer cells. Methods The taxol TPP-PEG-PE nanomicelles were prepared by membrane hydration method. Based on the drug loading, encapsulation efficiency and particle size, the preparation parameters of taxol TPP-PEG-PE nanomicelles were optimized. The preferred nano-drug delivery system was then characterized. The drug delivery system was evaluated by in vitro drug release, mitochondrial targeting, lung cancer cell toxicity, and apoptosis assay. Results The diameter of taxol TPP-PEG-PE nanomicelles was (18.7 ± 0.8) nm, Zeta potential was (13.4 ± 0.5) mV, and the results of TEM electron microscopy showed that the taxol TPP-PEG-PE nanomicelles were regular spheres of uniform size. Mitochondrial targeting experiments showed that TPP-PEG-PE nanomicelles can promote drug accumulation in mitochondrial sites. Lung cancer cytotoxicity assay showed that taxol TPP-PEG-PE nanomicelles had good anti-apoptotic effect, and Hoechst staining suggested that a large number of morphological changes were observated in apoptotic lung cancer cells. Taxol TPP-PEG-PE nanomicelles could significantly increase the pro- apoptotic Caspase-3 activity and reduce the expression of anti-apoptotic protein Bcl-2 and c-IAP1. They were all significantly superior to that of taxol-PEG-PE nanomicelles and taxol group (P < 0.01). Conclusion The taxol TPP-PEG-PE nanomicelles had good mitochondrial targeting of lung cancer cells and promoted the apoptosis of lung cancer cells. It was a potential and efficient drug delivery system for lung cancer cell mitochondria.

Anti-tumor effect of brucine-loaded chitosan nanoparticles in vitro / 药学学报

We designed two novel polymer materials N-glycyrrhetinic acid-polyethylene glycol-chitosan derivatives (NGPC) and N-quaternary ammonium-chitosan derivatives (NQC). We prepared three kinds of drug loaded chitosan nanoparticles (brucine/NGPC-NPs, brucine/NQC-NPs, brucine/MNPs) by ionic crosslinking method with brucine as a model drug and chitosan nanoparticles (brucine/NGPC-NPs, brucine/NQC-NPs) as the reference formulation. Using high content analysis, flow cytometry, immunofluorescence, transmission electron microscopy and other advanced technology, we tested the effect of 20 μg·mL-1 concentration of brucine solution and brucine/chitosan nanoparticles (brucine/CTS-NPs) in hepatocarcinoma (HepG2) cells and evaluated the apoptosis induced by the treatment. The results suggested that brucine-CTS/NPs had a strongest activity in killing tumor cells, and increased the total cell apoptosis rate with a significant formation of "crescent-shaped" body, swelling mitochondria, mitochondria cristae missing, decreased mitochondrial membrane potential and release of cytochrome C. The activity was enhanced by multifunctional nanocomposite particles that increased the cumulative amount of drug in the mitochondria for the anti-tumor effect.

Advances in mitochondrial targeting molecules in anticancer applications / 中国药学杂志

In recent years, with the in-depth research on mitochondria, people realize that mitochondria have a vital role for apopto-sis of cancer cells. This finding promotes the development of mitochondrial targeting agents. Anticancer drugs modified with mitochondrial targeting molecules specifically acts on mitochondria and induce apoptosis of tumor cells to achieve targeting anti-tumor effect, so that the efficacy is improved while systemic toxicity of anticancer drugs is reduced. Mitochondrial targeting molecules have broad potential applications in anticancer drugs. This paper reviews the latest research progress of mitochondrial targeting molecules for cancer therapy, providing a reference for the treatment of cancer from the mitochondrial pathway.

A Novel Cytosolic Isoform of Mitochondrial Trans-2-Enoyl-CoA Reductase Enhances Peroxisome Proliferator-Activated Receptor alpha Activity

BACKGROUND: Mitochondrial trans-2-enoyl-CoA reductase (MECR) is involved in mitochondrial synthesis of fatty acids and is highly expressed in mitochondria. MECR is also known as nuclear receptor binding factor-1, which was originally reported with yeast two-hybrid screening as a binding protein of the nuclear hormone receptor peroxisome proliferator-activated receptor alpha (PPARalpha). However, MECR and PPARalpha are localized at different compartment, mitochondria, and the nucleus, respectively. Therefore, the presence of a cytosolic or nuclear isoform of MECR is necessary for functional interaction between MECR and PPARalpha. METHODS: To identify the expression pattern of MECR and the cytosolic form of MECR (cMECR), we performed reverse transcription polymerase chain reaction (RT-PCR) with various tissue samples from Sprague-Dawley rats. To confirm the interaction between cMECR and PPARalpha, we performed several binding assays such as yeast two-hybrid, coimmunoprecipitation, and bimolecular fluorescence complementation. To observe subcellular localization of these proteins, immunocytochemistry was performed. A luciferase assay was used to measure PPARalpha activity. RESULTS: We provide evidence of an alternatively spliced variant of the rat MECR gene that yields cMECR. The cMECR lacks the N-terminal 76 amino acids of MECR and shows uniform distribution in the cytoplasm and nucleus of HeLa cells. cMECR directly bound PPARalpha in the nucleus and increased PPARalpha-dependent luciferase activity in HeLa cells. CONCLUSION: We found the cytosolic form of MECR (cMECR) was expressed in the cytosolic and/or nuclear region, directly binds with PPARalpha, and enhances PPARalpha activity.

Re-engineering the mitochondrial genomes in mammalian cells / 대한해부학회지

Mitochondria are subcellular organelles composed of two discrete membranes in the cytoplasm of eukaryotic cells. They have long been recognized as the generators of energy for the cell and also have been known to associate with several metabolic pathways that are crucial for cellular function. Mitochondria have their own genome, mitochondrial DNA (mtDNA), that is completely separated and independent from the much larger nuclear genome, and even have their own system for making proteins from the genes in this mtDNA genome. The human mtDNA is a small (~16.5 kb) circular DNA and defects in this genome can cause a wide range of inherited human diseases. Despite of the significant advances in discovering the mtDNA defects, however, there are currently no effective therapies for these clinically devastating diseases due to the lack of technology for introducing specific modifications into the mitochondrial genomes and for generating accurate mtDNA disease models. The ability to engineer the mitochondrial genomes would provide a powerful tool to create mutants with which many crucial experiments can be performed in the basic mammalian mitochondrial genetic studies as well as in the treatment of human mtDNA diseases. In this review we summarize the current approaches associated with the correction of mtDNA mutations in cells and describe our own efforts for introducing engineered mtDNA constructs into the mitochondria of living cells through bacterial conjugation.