Mitochondria as targets in angiogenesis inhibition

A bioenergetically-active ploy (glycerol sebacate)-based multiblock hydrogel improved diabetic wound healing through revitalizing mitochondrial metabolism

Diabetic wounds impose significant burdens on patients' quality of life and healthcare resources due to impaired healing potential. Factors like hyperglycemia, oxidative stress, impaired angiogenesis and excessive inflammation contribute to the delayed healing trajectory. Mounting evidence indicates a close association between impaired mitochondrial function and diabetic complications, including chronic wounds. Mitochondria are critical for providing energy essential to wound healing processes. However, mitochondrial dysfunction exacerbates other pathological factors, creating detrimental cycles that hinder healing. This study conducted correlation analysis using clinical specimens, revealing a positive correlation between mitochondrial dysfunction and oxidative stress, inflammatory response and impaired angiogenesis in diabetic wounds. Restoring mitochondrial function becomes imperative for developing targeted therapies. Herein, we synthesized a biodegradable poly (glycerol sebacate)-based multiblock hydrogel, named poly (glycerol sebacate)-co-poly (ethylene glycol)-co-poly (propylene glycol) (PEPGS), which can be degraded in vivo to release glycerol, a crucial component in cellular metabolism, including mitochondrial respiration. We demonstrate the potential of PEPGS-based hydrogels to improve outcomes in diabetic wound healing by revitalizing mitochondrial metabolism. Furthermore, we investigate the underlying mechanism through proteomics analysis, unravelling the regulation of ATP and nicotinamide adenine dinucleotide metabolic processes, biosynthetic process and generation during mitochondrial metabolism. These findings highlight the therapeutic potential of PEPGS-based hydrogels as advanced wound dressings for diabetic wound healing.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

The synergistic inhibitory effect of combining therapies targeting EGFR and mitochondria in sarcomas

Our group previously demonstrated that sarcoma cell lines were insensitive to epidermal growth factor receptor (EGFR) inhibitor gefitinib monotherapy. PENAO, an anti-tumour metabolic compound created in our laboratory, is currently in clinical trials. Considering the positive regulation of tumour energy production by both the EGFR signalling and tumour metabolism pathways, this study aimed to investigate the effect and mechanisms of combination therapy using gefitinib and PENAO in sarcoma cell lines in vitro and in vivo.

PENAO monotherapy reduced proliferation in 12 sarcoma cell lines. Combining gefitinib and PENAO resulted in synergistic inhibition in both a time- and dose-dependent manner in 3 sarcoma cell lines with less prominent monotherapy effects. Combined treatment significantly enhanced cell death and perturbed mitochondrial function. In vivo combination therapy with PENAO and gefitinib was non-toxic to mice and significantly delayed tumour growth and prolonged survival. At 20 days after treatment, tumours from the combination treated mice were significantly smaller than those from untreated and single drug treated mice. The survival curves also showed significant difference across and between groups.

The combination of PENAO and gefitinib in vitro and in vivo, shows promise as a treatment pathway in this poor outcome tumour.

α-Tocopheryl Succinate-Based Polymeric Nanoparticles for the Treatment of Head and Neck Squamous Cell Carcinoma

The aim of this work is to study, in an in vitro head and neck squamous cell carcinomas model the anti-angiogenic and anti-migratory properties of self-assembled polymeric nanoparticles (NPs) with demonstrated selective anticancer activity. The NPs are based on α-tocopheryl succinate (α-TOS) encapsulated in the hydrophobic core of the NPs. We analyzed the effect of the newly synthetized α-TOS-loaded NPs in proliferating endothelial cells and hypopharynx carcinoma squamous cells and measured markers of angiogenesis, apoptosis and reactive oxygen species (ROS). α-TOS-loaded NPs suppressed angiogenesis by inducing accumulation of ROS and inducing apoptosis of proliferating endothelial cells. These NPs also decrease the number and quality of capillary-like tubes in an in vitro three-dimensional (3D) experiment, decrease the production of the pro-angiogenic vascular endothelial growth factor and down-regulate the expression of its receptor. The anti-migratory efficacy of α-TOS is corroborated in hypopharynx carcinoma cells by decreasing the secretion of matrix metalloproteases 2 and 9 (MMP-2 and MMP-9) and inhibiting cell migration. These results confirm that α-TOS-based NPs not only present anticancer properties, but also antiangiogenic properties, therefore making them promising candidates for multi-active combinatorial anticancer therapy.

Triphenylphosphonium-modified mitochondria-targeted paclitaxel nanocrystals for overcoming multidrug resistance

Mitochondria are currently known as novel targets for treating cancer, especially for tumors displaying multidrug resistance (MDR). This present study aimed to develop a mitochondria-targeted delivery system by using triphenylphosphonium cation (TPP⁺)-conjugated Brij 98 as the functional stabilizer to modify paclitaxel (PTX) nanocrystals (NCs) against drug-resistant cancer cells. Evaluations were performed on 2D monolayer and 3D multicellular spheroids (MCs) of MCF-7 cells and MCF-7/ADR cells. In comparison with free PTX and the non-targeted PTX NCs, the targeted PTX NCs showed the strongest cytotoxicity against both 2D MCF-7 and MCF-7/ADR cells, which was correlated with decreased mitochondrial membrane potential. The targeted PTX NCs exhibited deeper penetration on MCF-7 MCs and more significant growth inhibition on both MCF-7 and MCF-7/ADR MCs. The proposed strategy indicated that the TPP⁺-modified NCs represent a potentially viable approach for targeted chemotherapeutic molecules to mitochondria. This strategy might provide promising therapeutic outcomes to overcome MDR.

VEGF stimulated the angiogenesis by promoting the mitochondrial functions

The vascular endothelial growth factor (VEGF) signaling pathway involved in angiogenesis which plays a pivotal role in normal development and also represents a major therapeutic target for tumors and intraocular neovascular disorders. The aims of the present study were to evaluate the effects of VEGF on endothelial cells and clarify the mechanism. Here, we showed that VEGF significantly stimulated the proliferation, migration and cell cycle of endothelial cells, and it also induced tube formation in vitro significantly. What's more, the mitochondrial functions were enhanced in response to VEGF, including mitochondrial oxidative respiration and intracellular ATP levels. The reactive oxygen species (ROS) production decreased, while the enzymes of ROS defence system, including catalase and glutathione peroxidase (GPX1), whose expression both increased in the VEGF stimulation. VEGF activated mammalian target of rapamycinm (mTOR) signaling pathway to promote the function of mitochondria. Rapamycin, the inhibitor of mTOR pathway could inhibit the proliferation and cell cycle induced by VEGF. In summary, our study identified that VEGF promoted the angiogenesis and provided evidence for mitochondria as new therapeutic target of VEGF signaling in the angiogenic vascular disorders.

Delivery of drugs and macromolecules to the mitochondria for cancer therapy

Mitochondria are organelles that have pivotal functions in producing the energy necessary for life and executing the cell death pathway. Targeting drugs and macromolecules to the mitochondria may provide an effective means of inducing cell death for cancer therapy, and has been actively pursued in the last decade. This review will provide a brief overview of mitochondrial structure and function, how it relates to cancer, and importantly, will discuss different strategies of mitochondrial delivery including delivery using small molecules, peptides, genes encoding proteins and MTSs, and targeting polymers/nanoparticles with payloads to the mitochondria. The advantages and disadvantages for each strategy will be discussed. Specific examples using the latest strategies for mitochondrial targeting will be evaluated, as well as potential opportunities for specific mitochondrial compartment localization, which may lead to improvements in mitochondrial therapeutics. Future perspectives in mitochondrial targeting of drugs and macromolecules will be discussed. Currently this is an under-explored area that is prime for new discoveries in cancer therapeutics.

Glutathione S-conjugates as prodrugs to target drug-resistant tumors

Living organisms are continuously exposed to xenobiotics. The major phase of enzymatic detoxification in many species is the conjugation of activated xenobiotics to reduced glutathione (GSH) catalyzed by the glutathione-S-transferase (GST). It has been reported that some compounds, once transformed into glutathione S-conjugates, enter the mercapturic acid pathway whose end products are highly reactive and toxic for the cell responsible for their production. The cytotoxicity of these GSH conjugates depends essentially on GST and gamma-glutamyl transferases (γGT), the enzymes which initiate the mercapturic acid synthesis pathway. Numerous studies support the view that the expression of GST and γGT in cancer cells represents an important factor in the appearance of a more aggressive and resistant phenotype. High levels of tumor GST and γGT expression were employed to selectively target tumor with GST- or γGT-activated drugs. This strategy, explored over the last two decades, has recently been successful using GST-activated nitrogen mustard (TLK286) and γGT-activated arsenic-based (GSAO and Darinaparsin) prodrugs confirming the potential of GSH-conjugates as anticancer drugs.

Role of endothelial cell metabolism in vessel sprouting

Endothelial cells (ECs) are quiescent for years but can plastically switch to angiogenesis. Vascular sprouting relies on the coordinated activity of migrating tip cells at the forefront and proliferating stalk cells that elongate the sprout. Past studies have identified genetic signals that control vascular branching. Prominent are VEGF, activating tip cells, and Notch, which stimulates stalk cells. After the branch is formed and perfused, ECs become quiescent phalanx cells. Now, emerging evidence has accumulated indicating that ECs not only adapt their metabolism when switching from quiescence to sprouting but also that metabolism regulates vascular sprouting in parallel to the control by genetic signals.

A phase 1 trial of intravenous 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) in patients with advanced solid tumours

BACKGROUND

4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) is a water-soluble mitochondrial toxin that binds to adenine nucleotide translocase in the inner mitochondrial membrane, thereby targeting cell proliferation. This phase 1 study investigated safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSAO as a daily 1-h infusion for 5 days a week for 2 weeks in every three. Pharmacodynamics of GSAO was evaluated by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and circulating markers of angiogenesis.

METHODS

Patients with advanced solid tumours received GSAO in a dose-escalation trial according to a standard '3 + 3' design that was guided by toxicity and, for the final dose escalation, by arsenic PK data.

RESULTS

A total of 34 patients were treated with GSAO across 9 dose levels (1.3-44.0 mg/m(2)). Treatment was well tolerated with few adverse events. An additional three patients were enrolled at the 12.4 mg/m(2) dose level following a DLT of derangement of liver function tests (grade 4). At the 44.0 mg/m(2) dose level, two out of three patients had DLTs (reversible encephalopathy; paroxysmal atrial fibrillation).

CONCLUSIONS

The MTD of GSAO was 22.0 mg/m(2)/day. There was no biomarker evidence from DCE-MRI or circulating markers of angiogenesis of an anti-vascular effect of GSAO.

Antibacterial evaluation of novel organoarsenic compounds by the microcalorimetric method

Antibacterial activities of novel organoarsenic compounds As(III)-containing Schiff bases on Escherichia coli (CCTCCAB91112) were investigated by microcalorimetry in this study. The experimental result showed that the arsenic(III)-containing Schiff bases at micromolar concentration exhibit strong inhibition on the E. coli. Specifically, the growth rate constant k decreased, and the generation time t G and the inhibitory ratio I (percentage) increased with the increased dose of the arsenicals as inhibitors. All of the arsenicals display the feature of considerable lag phase inhibition on the cell growth. The compound 4-(4-bromobenzaliminyl)phenylarsenoxide makes the lag phase of E. coli cell growth cycles to reach 650 min at 5 μmol/L. The compounds with donating electron groups at aromatic ring B have lower IC50 to present higher antibacterial activity. The compound 4-(4-hydroxyl-3-methoxylbenzaliminyl)phenylarsenoxide has the lowest IC50 (1.82 μmol/L) to show the strongest antibacterial activity among them.

Injectable and biodegradable poly(organophosphazene) gel containing silibinin: its physicochemical properties and anticancer activity

The biodegradable poly(organophosphazene) hydrogels were developed as a locally injectable drug carrier for a hydrophobic silibinin to overcome its limited bioavailability. The aqueous solution of poly(organophosphazene) enhanced the solubility of silibinin up to 2000 times compared with that of phosphate buffered saline (0.0415 vs. 84.55 mg/mL). Both aqueous polymer solutions with and without silibinin showed a sol-gel transition as a function of temperature. A faster in vitro degradation rate of the gel and drug release rate from the gel at pH 6.8 than those at pH 7.4 were observed when the degradation and release study on hydrogels were conducted at 37 °C. Silibinin was sustainedly released from the hydrogel mainly by a diffusion-controlled mechanism. The silibinin released from the hydrogel was shown to be effective considering the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In the HT-29 xenografted mice model, the intratumorally injected hydrogel containing silibinin exhibited a good antitumor effect in comparison with the control groups. The Western blotting indicated that one of the reasons for the enhanced antitumor effect of the hydrogel system was the sustained antiangiogenic effect of silibinin. The poly(organophosphazene) gels are expected to be an effective candidate of the locally injectable drug carrier for silibinin.

Mitochondrially targeted α-tocopheryl succinate is antiangiogenic: potential benefit against tumor angiogenesis but caution against wound healing

AIMS

A plausible strategy to reduce tumor progress is the inhibition of angiogenesis. Therefore, agents that efficiently suppress angiogenesis can be used for tumor suppression. We tested the antiangiogenic potential of a mitochondrially targeted analog of α-tocopheryl succinate (MitoVES), a compound with high propensity to induce apoptosis.

RESULTS

MitoVES was found to efficiently kill proliferating endothelial cells (ECs) but not contact-arrested ECs or ECs deficient in mitochondrial DNA, and suppressed angiogenesis in vitro by inducing accumulation of reactive oxygen species and induction of apoptosis in proliferating/angiogenic ECs. Resistance of arrested ECs was ascribed, at least in part, to the lower mitochondrial inner transmembrane potential compared with the proliferating ECs, thus resulting in the lower level of mitochondrial uptake of MitoVES. Shorter-chain homologs of MitoVES were less efficient in angiogenesis inhibition, thus suggesting a molecular mechanism of its activity. Finally, MitoVES was found to suppress HER2-positive breast carcinomas in a transgenic mouse as well as inhibit tumor angiogenesis. The antiangiogenic efficacy of MitoVES was corroborated by its inhibitory activity on wound healing in vivo.

INNOVATION AND CONCLUSION

We conclude that MitoVES, a mitochondrially targeted analog of α-tocopheryl succinate, is an efficient antiangiogenic agent of potential clinical relevance, exerting considerably higher activity than its untargeted counterpart. MitoVES may be helpful against cancer but may compromise wound healing.

Anti-angiogenic activity and intracellular distribution of epigallocatechin-3-gallate analogs

Angiogenesis, a process of construction of new blood capillaries, is crucial for tumor progression and metastasis. Our previous studies demonstrated that a component of green tea, epigallocatechin-3-gallate (EGCG), suppressed angiogenesis and subsequent tumor growth. In this study, to elucidate the detailed mechanism of the anti-angiogenic effect of EGCG and to enhance the antiangiogenic activity of EGCG, we designed and synthesized EGCG derivatives and examined their biological effect and intracellular localization in human umbilical vein endothelial cells (HUVECs). EGCG derivatives aminopentyl dideoxyEGCG and aminopentyl dideoxygallocatechin-3-gallate (cis-APDOEGCG and trans-APDOEGCG) had an enhanced inhibitory effect on the proliferation when used at more than 30 µM. To elucidate antiangiogenic effect of EGCG, we used a 1 µM concentration for subsequent experiments where no effect on proliferation was observed. These EGCG derivatives showed a stronger inhibitory effect on migration, invasion, and tube formation by HUVECs than the non-derivatized EGCG. Furthermore, the derivatives induced a change in the distribution of F-actin and subsequent morphology of the HUVECs. Next, we synthesized fluorescent TokyoGreen-conjugated EGCG derivative (EGCG-TG) and observed the distribution in HUVECs under a confocal laser scanning microscope. Abundant fluorescence was observed in the cells after a 3-h incubation, and was localized in mitochondria as well as in cytoplasm. These results suggest that EGCG was incorporated into the HUVECs, that a portion of it entered into their mitochondria.

Mitochondrial metabolism inhibitors for cancer therapy

Cancer cells catabolise nutrients in a different way than healthy cells. Healthy cells mainly rely on oxidative phosphorylation, while cancer cells employ aerobic glycolysis. Glucose is the main nutrient catabolised by healthy cells, while cancer cells often depend on catabolism of both glucose and glutamine. A key organelle involved in this altered metabolism is mitochondria. Mitochondria coordinate the catabolism of glucose and glutamine across the cancer cell. Targeting mitochondrial metabolism in cancer cells has potential for the treatment of this disease. Perhaps the most promising target is the hexokinase-voltage dependent anion channel-adenine nucleotide translocase complex that spans the outer- and inner-mitochondrial membranes. This complex links glycolysis, oxidative phosphorylation and mitochondrial-mediated apoptosis in cancer cells. This review discusses cancer cell mitochondrial metabolism and the small molecule inhibitors of this metabolism that are in pre-clinical or clinical development.