Disulfide cross-linked micelles of novel HDAC inhibitor thailandepsin A for the treatment of breast cancer

Disulfide bonds as a molecular switch of enzyme-activatable anticancer drug precise release for fluorescence imaging and enhancing tumor therapy

Enzyme-activatable drug delivery systems have been developed for cancer diagnosis and therapy. However, targeted intracellular drug delivery is a challenge for precisely tumor imaging and therapy due to the increased stability of copolymer nanoparticles (NPs) is accompanied by a notable decrease in enzyme degradation. Herein, disulfide bond was designed as an enzyme-activatable molecular switch of SS-P(G2)2/DOX NPs. The copolymer NPs consists of polyvinylpyrrolidone (PVP) with disulfide bonds in the center and enzyme-degradable peptide dendrites (Phe-Lys) to form dendritic-linear-dendritic triblock copolymers (TBCs). The amphiphilic TBCs could be split into two identical amphiphilic diblock copolymers (DBCs) by glutathione (GSH) in cancer cells specifically while maintaining the same hydrophilic-lipophilic equilibrium. This structural transformation significantly reduced the stability of copolymer NPs and enhanced sensitivity of DOX release by cathepsin B-activated. Subsequently, the released DOX acted as an indicator of fluorescence imaging and chemotherapy drug for cancer cells. The polymeric NPs achieved excellent drug-loaded stability and prolonged blood circulation in vivo, and realized fluorescence imaging and specific cancer cell killing capabilities by responding to the overexpression of GSH and cathepsin B in tumor cells. Furthermore, the copolymer NPs demonstrated excellent blood compatibility and biosafety. Therefore, a novel strategy based on one tumor marker acting as the switch for another tumor microenvironment responsive drug delivery system could be designed for tumor intracellular imaging and chemotherapy.

Advances in the Delivery and Development of Epigenetic Therapeutics for the Treatment of Cancer

Gene expression at the transcriptional level is altered by epigenetic modifications such as DNA methylation, histone methylation, and acetylation, which can upregulate, downregulate, or entirely silence genes. Pathological dysregulation of epigenetic processes can result in the development of cancer, neurological problems, metabolic disorders, and cardiovascular diseases. It is of promising therapeutic interest to find medications that target these epigenetic alterations. Despite the enormous amount of work that has been done in this area, very few molecules have been approved for clinical purposes. This article provides a comprehensive review of recent advances in epigenetic therapeutics for cancer, with a specific focus on emerging delivery and development strategies. Various delivery systems, including pro-drugs, conjugated molecules, nanoparticles (NPs), and liposomes, as well as remedial strategies such as combination therapies, and epigenetic editing, are being investigated to improve the efficacy and specificity of epigenetic drugs (epi-drugs). Furthermore, the challenges associated with available epi-drugs and the limitations of their translation into clinics have been discussed. Target selection, isoform selectivity, physiochemical properties of synthesized molecules, drug screening, and scalability of epi-drugs from preclinical to clinical fields are the major shortcomings that are addressed. This Review discusses novel strategies for the identification of new biomarkers, exploration of the medicinal chemistry of epigenetic modifiers, optimization of the dosage regimen, and design of proper clinical trials that will lead to better utilization of epigenetic modifiers over conventional therapies. The integration of these approaches holds great potential for improving the efficacy and precision of epigenetic treatments, ultimately benefiting cancer patients.

Nanomedicine and epigenetics: New alliances to increase the odds in pancreatic cancer survival

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers worldwide, primarily due to its robust desmoplastic stroma and immunosuppressive tumor microenvironment (TME), which facilitate tumor progression and metastasis. In addition, fibrous tissue leads to sparse vasculature, high interstitial fluid pressure, and hypoxia, thereby hindering effective systemic drug delivery and immune cell infiltration. Thus, remodeling the TME to enhance tumor perfusion, increase drug retention, and reverse immunosuppression has become a key therapeutic strategy. In recent years, targeting epigenetic pathways has emerged as a promising approach to overcome tumor immunosuppression and cancer progression. Moreover, the progress in nanotechnology has provided new opportunities for enhancing the efficacy of conventional and epigenetic drugs. Nano-based drug delivery systems (NDDSs) offer several advantages, including improved drug pharmacokinetics, enhanced tumor penetration, and reduced systemic toxicity. Smart NDDSs enable precise targeting of stromal components and augment the effectiveness of immunotherapy through multiple drug delivery options. This review offers an overview of the latest nano-based approaches developed to achieve superior therapeutic efficacy and overcome drug resistance. We specifically focus on the TME and epigenetic-targeted therapies in the context of PDAC, discussing the advantages and limitations of current strategies while highlighting promising new developments. By emphasizing the immense potential of NDDSs in improving therapeutic outcomes in PDAC, our review paves the way for future research in this rapidly evolving field.

HDAC-an important target for improving tumor radiotherapy resistance

Radiotherapy is an important means of tumor treatment, but radiotherapy resistance has been a difficult problem in the comprehensive treatment of clinical tumors. The mechanisms of radiotherapy resistance include the repair of sublethal damage and potentially lethal damage of tumor cells, cell repopulation, cell cycle redistribution, and reoxygenation. These processes are closely related to the regulation of epigenetic modifications. Histone deacetylases (HDACs), as important regulators of the epigenetic structure of cancer, are widely involved in the formation of tumor radiotherapy resistance by participating in DNA damage repair, cell cycle regulation, cell apoptosis, and other mechanisms. Although the important role of HDACs and their related inhibitors in tumor therapy has been reviewed, the relationship between HDACs and radiotherapy has not been systematically studied. This article systematically expounds for the first time the specific mechanism by which HDACs promote tumor radiotherapy resistance in vivo and in vitro and the clinical application prospects of HDAC inhibitors, aiming to provide a reference for HDAC-related drug development and guide the future research direction of HDAC inhibitors that improve tumor radiotherapy resistance.

HDAC inhibitors enhance the anti-tumor effect of immunotherapies in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common liver malignancy with a poor prognosis and increasing incidence, remains a serious health problem worldwide. Immunotherapy has been described as one of the ideal ways to treat HCC and is transforming patient management. However, the occurrence of immunotherapy resistance still prevents some patients from benefiting from current immunotherapies. Recent studies have shown that histone deacetylase inhibitors (HDACis) can enhance the efficacy of immunotherapy in a variety of tumors, including HCC. In this review, we present current knowledge and recent advances in immunotherapy-based and HDACi-based therapies for HCC. We highlight the fundamental dynamics of synergies between immunotherapies and HDACis, further detailing current efforts to translate this knowledge into clinical benefits. In addition, we explored the possibility of nano-based drug delivery system (NDDS) as a novel strategy to enhance HCC treatment.

Stimuli-responsive crosslinked nanomedicine for cancer treatment

Nanomedicines are attractive paradigms to deliver drugs, contrast agents, immunomodulators, and gene editors for cancer therapy and diagnosis. However, the currently developed nanomedicine suffers from poor serum stability, premature drug release, and lack of responsiveness. Crosslinking strategy can be utilized to overcome these shortcomings by employing stimuli-responsive chemical bonds to tightly hold the nanostructure and releasing the payloads spatiotemporally in a highly controlled manner. In this Review, we summarize the recently ingenious design of the stimuli-responsive crosslinked nanomedicines (SCN) in the field of cancer treatment and their advances in circumventing the drawbacks of the conventional drug delivery system. We classify the SCNs into three categories based on the crosslinking strategies, including built-in, on-surface, and inter-particle crosslinking nanomedicines. Thanks to the stimuli-responsive crosslinkages, SCNs are capable of keeping robust stability during systemic circulation. They also respond to the particular tumoral conditions to experience a series of dynamic changes, such as the changes in size, surface charge, targeting moieties, integrity, and imaging signals. These characteristics allow them to efficiently overcome different biological barriers and substantially improve the drug delivery efficiency, tumor-targeting ability, and imaging sensitivities. With the examples discussed, we envision that our perspectives can inspire more attempts to engineer intelligent nanomedicine to achieve effective cancer therapy and diagnosis.

Suberoylanilide hydroxamic acid (SAHA) inhibits transforming growth factor-beta 2-induced increases in aqueous humor outflow resistance

Transforming growth factor-beta 2 (TGF-β2) is highly concentrated in the aqueous humor of primary open-angle glaucoma patients. TGF-β2 causes fibrosis of outflow tissues, such as the trabecular meshwork (TM), and increases intraocular pressure by increasing resistance to aqueous humor outflow. Recently, histone deacetylase (HDAC) activity was investigated in fibrosis in various tissues, revealing that HDAC inhibitors suppress tissue fibrosis. However, the effect of HDAC inhibitors on fibrosis in the eye was not determined. Here, we investigated the effect of suberoylanilide hydroxamic acid (SAHA), an HDAC inhibitor, on TGF-β2-induced increased resistance to aqueous humor outflow. We found that SAHA suppressed TGF-β2-induced outflow resistance in perfused porcine eyes. Moreover, SAHA cotreatment suppressed TGF-β2-induced ocular hypertension in rabbits. The permeability of monkey TM (MTM) and Schlemm’s canal (MSC) cell monolayers was decreased by TGF-β2 treatment. SAHA inhibited the effects of TGF-β2 on the permeability of these cells. TGF-β2 also increased the expression of extracellular matrix proteins (fibronectin and collagen type I or IV) in MTM, MSC, and human TM (HTM) cells, while SAHA inhibited TGF-β2-induced extracellular matrix protein expression in these cells. SAHA also inhibited TGF-β2-induced phosphorylation of Akt and ERK, but did not inhibit Smad2/3 phosphorylation, the canonical pathway of TGF-β signaling. Moreover, SAHA induced the expression of phosphatase and tensin homolog, a PI3K/Akt signaling factor, as well as bone morphogenetic protein 7, an endogenous antagonist of TGF-β. These results imply that SAHA prevents TGF-β2-induced increases in outflow resistance and regulates the non-Smad pathway of TGF-β signaling in TM and MSC cells.

Hybrid artificial cell-mediated epigenetic inhibition in metastatic lung cancer

HYPOTHESIS

Histone deacetylase inhibitors (HDACIs), such as vorinostat (suberoylanilide hydroxamic acid, SAHA), has become a promising approach for the treatment of metastatic lung cancer. However, HDACIs usually showed a short circulation lifetime, low specificity, and low bioavailability, which limited their therapeutic effect in this field. We supposed that the use of biomimetic nanoparticles enabled to overcome the disadvantages of HDACIs, and improved the inhibition of metastatic lung cancer.

EXPERIMENTS

SAHA was encapsulated into a pH-sensitive core constructed with Poly(lactic-co-glycolic acid) (PLAG) and 1,2-dioleoyloxy-3-(trimethylammonium) propane (DOTAP), followed by the camouflage with hybrid membranes derived from red blood cells and metastatic NCI-H1299 lung cancer cells (HRPDS). The physical and chemical properties were characterized with Transmission electron microscope (TEM), Size & Zeta potential analyzer. The cellular uptake was analyzed with Confocal laser scanning microscope (CLSM) and Flow cytometry (FACS). The biological effect analysis was performed with Western blotting (WB), RNA-Sequencing (RNA-Seq), and ChIP-Sequencing (ChIP-Seq).

FINDINGS

HRPDS exhibited enhanced circulation lifetime in vivo and homotypic targeting to metastatic cells in the metastatic foci, which induced significant suppression of lung cancer liver metastasis. Our work opens a new avenue for the treatment of metastatic lung cancer by epigenetic inhibition based on this style of biomimetic nanovehicle.

LHRH-Targeted Redox-Responsive Crosslinked Micelles Impart Selective Drug Delivery and Effective Chemotherapy in Triple-Negative Breast Cancer

Systemic chemotherapy is efficacious against triple-negative breast cancer (TNBC), but it is often associated with serious side effects. Here, a luteinizing hormone-releasing hormone (LHRH) receptor-targeted and tumor microenvironment-responsive nanoparticle system to selectively deliver chemotherapeutic drugs to TNBC cells, is reported. This delivery system (termed "LHRH-DCMs") contains poly(ethylene glycol) and dendritic cholic acid as a micellar carrier, reversible intra-micellar disulfide bond as a redox-responsive crosslink, and synthetic high-affinity (D-Lys)-LHRH peptide as a targeting moiety. LHRH-DCMs exhibit high drug loading efficiency, optimal particle size, good colloidal stability, and glutathione-responsive drug release. As expected, LHRH-DCMs are more efficiently internalized into human TNBC cells through receptor-mediated endocytosis, resulting in stronger cytotoxicity against these cancer cells than the non-targeted counterpart when encapsulated with paclitaxel (PTX). Furthermore, near-infrared fluorescence and magnetic resonance imaging demonstrate that LHRH-DCMs facilitate the tumor distribution and penetration of payloads in three different animal models of breast cancer, including cell line-derived xenograft (CDX), patient-derived xenograft (PDX), and transgenic mammary carcinoma. Finally, in vivo therapeutic studies show that PTX-LHRH-DCMs outperform both the corresponding nontargeted PTX-DCMs and the current clinical formulation (Taxol) in an orthotopic TNBC model. These results provide new insights into approaches for precise drug delivery of TNBC.

Two-way magnetic resonance tuning and enhanced subtraction imaging for non-invasive and quantitative biological imaging

Distance-dependent magnetic resonance tuning (MRET) technology enables the sensing and quantitative imaging of biological targets in vivo, with the advantage of deep tissue penetration and fewer interactions with the surroundings as compared with those of fluorescence-based Förster resonance energy transfer. However, applications of MRET technology in vivo are currently limited by the moderate contrast enhancement and stability of T₁-based MRET probes. Here we report a new two-way magnetic resonance tuning (TMRET) nanoprobe with dually activatable T₁ and T₂ magnetic resonance signals that is coupled with dual-contrast enhanced subtraction imaging. This integrated platform achieves a substantially improved contrast enhancement with minimal background signal and can be used to quantitatively image molecular targets in tumours and to sensitively detect very small intracranial brain tumours in patient-derived xenograft models. The high tumour-to-normal tissue ratio offered by TMRET in combination with dual-contrast enhanced subtraction imaging provides new opportunities for molecular diagnostics and image-guided biomedical applications.

Recent advances on small-molecule nanomedicines for cancer treatment

Nanomedicines have made important contributions in the development of cancer therapies due to their tumor selectivity, multifunctionality, and synergistic effect between the payloads. In addition to the required pharmaceutical ingredients, nanomedicines are generally composed of nonpharmaceutical excipients. These excipients generally form a large proportion of the nanomedicine, and they may have potential toxicity and greatly increase the cost for drug development. Small molecule nanomedicines (SMNs) minimize or abandon the excipients and are directly assembled from pharmaceutical ingredients, which can largely improve the drug delivery efficiency and biosafety while also relieving the financial burden of drug development. In this review, we summarize recently developed SMNs that are composed of a single drug, physical mixtures of multiple drugs, drug-drug covalent conjugates, dyes with drugs, photosensitizers with drugs, photosensitizers with peptides, and drugs with peptides. This review focuses on the SMN's applications in cancer treatments, their limitations, and the future development outlook of SMNs. We hope that our insights on SMNs may be helpful to the future of drug development and make nanomedicine more powerful in the battle with cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Solanesol derived therapeutic carriers for anticancer drug delivery

Metabolites of a large number of inert drug carriers can cause long-term exogenous biological toxicity. Therefore, carriers with simultaneous therapeutic effects may be a good choice for drug delivery. Herein, a series of pharmacologically active solanesol derivatives were synthesized and investigated for use as micellar drug carriers for cancer therapy. Solanesyl thiosalicylic acid (STS) was first synthesized by introducing a thiosalicylic acid group to solanesol, inspired by the characteristic structure of farnesyl thiosalicylic acid (FTS) which is a non-toxic inhibitor of all active forms of the RAS protein. Then, two amphiphilic derivatives of STS were formed with ester- and hydrazone (HZ)-bond linked methyl poly(ethylene glycol)(mPEG), mPEG-STS and mPEG-HZ-STS, respectively. The PEGylated STS could be formed stable nano-sized micelles loaded with Doxorubicin (DOX). In vitro, DOX loaded mPEG-STS and mPEG-HZ-STS micelles exhibited stronger tumor inhibition ability compared with free DOX. In vivo, blank mPEG-STS and mPEG-HZ-STS micelles showed an obvious inhibiting effect on tumor growth while the drug loaded micelles had the greatest tumor inhibition effect. The enhanced therapeutic effects and the synergistic effect observed with this solanesol-based drug delivery system could be attributed to the inherent therapeutic qualities of the drug carriers.

Pulmonary Carcinoid Surface Receptor Modulation Using Histone Deacetylase Inhibitors

Pulmonary carcinoids are a type of neuroendocrine tumor (NET) accounting for 1–2% of lung cancer cases. Currently, Positron Emission Tomography (PET)/CT based on the radiolabeled sugar analogue [¹⁸F]-FDG is used to diagnose and stage pulmonary carcinoids, but is suboptimal due to low metabolic activity in these tumors. A new technique for pulmonary carcinoid imaging, using PET/CT with radiolabeled somatostatin analogs that specifically target somatostatin receptor subtype 2 (SSTR2), is becoming more standard, as many tumors overexpress SSTR2. However, pulmonary carcinoid patients with diminished SSTR2 expression are not eligible for this imaging or any type of SSTR2-specific treatment. We have found that histone deacetylase (HDAC) inhibitors can upregulate the expression of SSTR2 in pulmonary carcinoid cell lines. In this study, we used a non-cytotoxic dose of HDAC inhibitors to induce pulmonary carcinoid SSTR2 expression in which we confirmed in vitro and in vivo. A non-cytotoxic dose of the HDAC inhibitors: thailandepsin A (TDP-A), romidepsin (FK228), suberoylanilide hydroxamic acid (SAHA), AB3, and valproic acid (VPA) were administered to promote SSTR2 expression in pulmonary carcinoid cell lines and xenografts. This SSTR2 upregulation technique using HDAC inhibitors could enhance radiolabeled somatostatin analog-based imaging and the development of potential targeted treatments for pulmonary carcinoid patients with marginal or diminished SSTR2 expression.

The ROMP: A Powerful Approach to Synthesize Novel pH-Sensitive Nanoparticles for Tumor Therapy

Fast clearance, metabolism, and systemic toxicity are major limits for the clinical use of anti-cancer drugs. Histone deacetylase inhibitors (HDACi) present these defects, despite displaying promising anti-tumor properties on tumor cells in vitro and in in vivo models of cancer. The specific delivery of anti-cancer drugs into the tumor should improve their clinical benefit by limiting systemic toxicity and by increasing the anti-tumor effect. This paper deals with the synthesis of the polymeric nanoparticle platform, which was produced by Ring-Opening Metathesis Polymerization (ROMP), able to release anti-cancer drugs in dispersion, such as histone deacetylase inhibitors, into mesothelioma tumors. The core-shell nanoparticles (NPs) have stealth properties due to their poly(ethylene oxide) shell and can be viewed as universal nano-carriers on which any alkyne-modified anti-cancer molecule can be grafted by click chemistry. A cleavage reaction of the chemical bond between NPs and drugs through the contact of NPs with a medium presenting an acidic pH, which is typically a cancer tumor environment or an acidic intracellular compartment, induces a controlled release of the bioactive molecule in its native form. In our in vivo syngeneic model of mesothelioma, a highly selective accumulation of the particles in the tumor was obtained. The release of the drugs led to an 80% reduction of tumor weight for the best compound without toxicity. Our work demonstrates that the use of theranostic nanovectors leads to an optimized delivery of epigenetic inhibitors in tumors, which improves their anti-tumor properties in vivo.

Reversibly disulfide cross-linked micelles improve the pharmacokinetics and facilitate the targeted, on-demand delivery of doxorubicin in the treatment of B-cell lymphoma

Doxorubicin (DOX) is commonly used to treat human malignancies, and its efficacy can be maximized by limiting the cardiac toxicity when combined with nanoparticles. Here, we reported a unique type of reversibly disulfide cross-linked micellar formulation of DOX (DOX-DCMs) for the targeted therapy of B-cell lymphoma. DOX-DCMs exhibited high drug loading capacity, optimal particle sizes (15-20 nm), outstanding stability in human plasma, and stimuli-responsive drug release profile under reductive conditions. DOX-DCMs significantly improved the pharmacokinetics of DOX, and its elimination half-life (t1/2) and area under curve (AUC) were 5.5 and 12.4 times of that of free DOX, respectively. Biodistribution studies showed that DOX-DCMs were able to preferentially accumulate in the tumor site and significantly reduce the cardiac uptake of DOX. In a xenograft model of human B-cell lymphoma, compared with the equivalent dose of free DOX and non-crosslinked counterpart, DOX-DCMs not only significantly inhibited the tumor growth and prolonged the survival rate, but also remarkably reduced DOX-associated cardiotoxicity. Furthermore, the exogenous administration of N-acetylcysteine (NAC) at 24 h further improved the therapeutic efficacy of DOX-DCMs, which provides a "proof-of-concept" for precise drug delivery on-demand, and may have great translational potential as future cancer nano-therapeutics.

Natural Products and Chemical Biology Tools: Alternatives to Target Epigenetic Mechanisms in Cancers

DNA methylation and histone acetylation are widely studied epigenetic modifications. They are involved in numerous pathologies such as cancer, neurological disease, inflammation, obesity, etc. Since the discovery of the epigenome, numerous compounds have been developed to reverse DNA methylation and histone acetylation aberrant profile in diseases. Among them several were inspired by Nature and have a great interest as therapeutic molecules. In the quest of finding new ways to target epigenetic mechanisms, the use of chemical tools is a powerful strategy to better understand epigenetic mechanisms in biological systems. In this review we will present natural products reported as DNMT or HDAC inhibitors for anticancer treatments. We will then discuss the use of chemical tools that have been used in order to explore the epigenome.

A facile strategy for fine-tuning the stability and drug release of stimuli-responsive cross-linked micellar nanoparticles towards precision drug delivery

Precision drug delivery has a great impact on the application of precision oncology for better patient care. Here we report a facile strategy for fine-tuning the stability, drug release and responsiveness of stimuli-responsive cross-linked nanoparticles towards precision drug delivery. A series of micellar nanoparticles with different levels of intramicellar disulfide crosslinkages could be conveniently produced with a mixed micelle approach. These micellar nanoparticles were all within a size range of 25-40 nm so that they could take full advantage of the enhanced permeability and retention (EPR) effect for tumor-targeted drug delivery. The properties of these nanoparticles such as critical micelle concentration (CMC), stability, drug release and responsiveness to a reductive environment could be well correlated with the levels of crosslinking (LOC). Compared to the micellar nanoparticles with a LOC at 0% that caused the death of animals of two species (mouse and rat) due to the acute toxicity such as hemolysis, the nanoparticles at all other levels of crosslinking were much safer to be administered into animals. The in vitro antitumor efficacy of micellar nanoparticles crosslinked at lower levels (20% & 50%) were much more effective than that of 100% crosslinked micellar nanoparticles in SKOV-3 ovarian cancer cells.

The Detailed Comparison of Cell Death Detected by Annexin V-PI Counterstain Using Fluorescence Microscope, Flow Cytometry and Automated Cell Counter in Mammalian and Microalgae Cells

The evaluation of cell wellness is an important task for molecular biology research. This mainly comprises the assessment for morphology and viability of culturing cells. Annexin V-Propidium iodide counterstaining has been currently one of the common and easy methods to discriminate apoptotic and necrotic cell profiles. The method is operated by fluorescence-based detection of counterstain via laser beam-employed instruments including flow cytometer, fluorescence microscope and automated cell counter. The detection is primarily conducted based on the same principle; however the efficiency of instruments may vary. Here we evaluated the efficiency of those instruments for the clear-cut detection of cell death through various mammalian and microalgae cell lines. To the best of our knowledge, this is the first study revealing comparative analyses of apoptotic and necrotic cells in mammalian and microalgae cells using Annexin V-PI counterstain detected by flow cytometer, fluorescence microscope and automated cell counter. Fluorescence microscope and cell counter instruments were also tested and compared for the traditional trypan blue-based cell viability detection performance. For these, cell death was induced by UV-irradiation and/or bee venom for mammalian (pancreatic cancer, metastatic breast cancer and mouse fibroblasts) and microalgae cells (Chlorella vulgaris), respectfully. Findings postulated that automated cell counter and fluorescence microscopy revealed similar patterns for the detection by both counterstain and trypan blue in mammalian cells. Interestingly, flow cytometry did provide an accurate and significant detection for only one mammalian cell line when UV-treatment was followed by routine Annexin V-Propidium iodide counterstaining. Unlike, only flow cytometry revealed a significant change in the detection of death of microalgae cells by Annexin V-Propidium iodide method, but both Annexin and conventional trypan blue methods were not applicable for the automated cell counter and microscopic detections for microalgae cells. The related outputs propose that the obtaining reliable quantitation strongly depends on cell type and instruments used. These suggest the necessity of optimization and validation endeavors before any cell death detection initiative. The analytical outcomes present insights into detailed assessment of cell death detection of eukaryotic cells and provide a direction to researchers to consider.

Novel redox-responsive polymeric magnetosomes with tunable magnetic resonance property for in vivo drug release visualization and dual-modal cancer therapy

Monitoring of in vivo drug release from nan by non-invasive approaches Remains very challenging. Herein we report on novel redox-responsive polymeric magnetosomes (PolyMags) with tunable magnetic resonance imaging (MRI) properties for in vivo drug release monitoring and effective dual-modal cancer therapy. The encapsulation of doxorubicin (DOX) significantly decreased PolyMags' T2 contrast enhancement and transverse relaxation rate R2, depending on the drug loading level. The T2 enhancement and R2 could be recovered once the drug was released upon PolyMags' disassembly. T2 & T2* MRI and diffusion-weighted imaging (DWI) were utilized to quantitatively study the correlation between MRI signal changes and drug release, and discover the MR tuning mechanisms. We visualized the in vivo drug release pattern based on such tunable MRI capability via monitoring the changes in T2-weighted images, T2 & T2* maps and R2 & R2* values. Interestingly, the PolyMags possessed excellent photothermal effect, which could be further enhanced upon DOX loading. The PolyMags were highly efficacious to treat breast tumors on xenograft model with tumor-targeted photothermal-and chemo-therapy, achieving a complete cure rate of 66.7%. The concept reported here is generally applicable to other micellar and liposomal systems for image-guided drug delivery & release applications toward precision cancer therapy.

Nanoformulated paclitaxel and AZD9291 synergistically eradicate non-small-cell lung cancers in vivo

AIM

This study aims to develop new nanoformulations of EGFR T790M targeted inhibitor AZD9291 and paclitaxel (PTX) for combination therapy of lung cancer.

MATERIALS & METHODS

We prepared and characterized PTX- and AZD9291-loaded disulfide cross-linking micelles (DCMs), and evaluate their combination effect and toxicity in vitro and in lung cancer-bearing mice.

RESULTS

Drug-loaded DCMs were relatively small in size, and possessed glutathione-responsive drug release. The combination of PTX-DCMs and AZD92921-DCMs exhibited strong synergistic effects in both cell line and in vivo without additional toxicity. Molecular studies demonstrated the synergistic modification in both IKB-α/NF-κB/Bcl-2 and EGFR/Akt pathways.

CONCLUSION

The combination of DCM-loaded AZD9291 and PTX could potentially offer more effective and less toxicity treatment options for lung cancer patients.

Interaction of spin-labeled HPMA-based nanoparticles with human blood plasma proteins - the introduction of protein-corona-free polymer nanomedicine

In this paper, we revised the current understanding of the protein corona that is created on the surface of nanoparticles in blood plasma after an intravenous injection. We have focused on nanoparticles that have a proven therapeutic outcome. These nanoparticles are based on two types of biocompatible amphiphilic copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA): a block copolymer, poly(ε-caprolactone) (PCL)-b-poly(HPMA), and a statistical HPMA copolymer bearing cholesterol moieties, which have been tested both in vitro and in vivo. We studied the interaction of nanoparticles with blood plasma and selected blood plasma proteins by electron paramagnetic resonance (EPR), isothermal titration calorimetry, dynamic light scattering, and cryo-transmission electron microscopy. The copolymers were labeled with TEMPO radicals at the end of hydrophobic PCL or along the hydrophilic HPMA chains to monitor changes in polymer chain dynamics caused by protein adsorption. By EPR and other methods, we were able to probe specific interactions between nanoparticles and blood proteins, specifically low- and high-density lipoproteins, immunoglobulin G, human serum albumin (HSA), and human plasma. It was found that individual proteins and plasma have very low binding affinity to nanoparticles. We observed no hard corona around HPMA-based nanoparticles; with the exception of HSA the proteins showed no detectable binding to the nanoparticles. Our study confirms that a classical "hard corona-soft corona" paradigm is not valid for all types of nanoparticles and each system has a unique protein corona that is determined by the nature of the NP material.

Extremely long tumor retention, multi-responsive boronate crosslinked micelles with superior therapeutic efficacy for ovarian cancer

Mortality rates for ovarian cancer have declined only slightly in the past forty years since the "War on Cancer" was declared. The current standard care of ovarian cancer is still cytoredutive surgery followed by several cycles of chemotherapy. The severe adverse effect from chemotherapy drug is a leading cause for the patients to fail in long term therapy post-surgery. New nanocarriers able to minimize the premature drug release in blood circulation while releasing drug on-demand at tumor site have profound impact on the improvement of the efficacy and toxicity profile of the chemotherapeutic drugs. Here we reported a unique type of extremely long tumor retention, multi-responsive boronate crosslinked micelles (BCM) for ovarian cancer therapy. We systemically investigated the stability of BCM in serum and plasma, and their responsiveness to acidic pH and cis-diols (such as mannitol, a safe FDA approved drug for diuresis) through particle size measurement and förster resonance energy transfer (FRET) approach. Paclitaxel (PTX) loaded BCM (BCM-PTX) exhibited higher stability than non-crosslinked micelles (NCM) in the presence of plasma or serum. BCMs possessed a longer in vivo blood circulation time when compared to NCM. Furthermore, BCM could be disassembled in an acidic pH environment or by administrating mannitol, facilitating drug release in an acidic tumor environment and triggered by exogenous stimuli after drug enrichment in tumor mass. Near infra-red fluorescence (NIRF) imaging on SKOV-3 ovarian cancer mouse model demonstrated that the NIR dye DiD encapsulated BCM could preferentially accumulate in tumor site and their tumor retention was very long with still 66% remained on 12th day post injection. DiD-NCM had similar high-level uptake in tumor with DiD-BCM within the first 3days, its accumulation, however, decreased obviously on 4th day and only 15% dye was left 12days later. In both formulations, the dye uptake in normal organs was mostly washed away within the first 24-48h. In in vivo tumor treatment study, PTX loaded BCM showed superior therapeutic efficacy than that of NCM and Taxol. The mice could tolerate 20mg/kg PTX formulated in nano-formulations, which doubled the maximum tolerated dose (MTD) of Taxol. The administration of mannitol 24h after BCM-PTX injection further improved the tumor therapeutic effect and elongated the survival time of the mice. The novel boronate-catechol crosslinked nanocarrier platform demonstrated its superior capability in targeted drug delivery, which is not only useful for ovarian cancer treatment but will also be beneficial for the therapy of many other solid tumors.

Histone deacetylase inhibitor thailandepsin-A activates Notch signaling and suppresses neuroendocrine cancer cell growth in vivo

Novel therapies for neuroendocrine (NE) cancers are desperately needed as they frequently present as metastatic disease and cause debilitating symptoms by secreting excessive hormones. Induction of Notch isoforms has a tumor suppressive effect in NE cancer cell lines, and we have observed that histone deacetylase inhibitors (HDACi) potently activate Notch. In this study, we describe the potential for Burkholderia thailandensis-derived class I HDACi thailandepsin A (TDP-A) as a Notch activator and therapeutic agent against NE cancer. IC₅₀ for TDP-A was determined to be 4-6 nM in NE cancer cell lines (BON, MZ-CRC-1, and TT) without cytotoxicity to lung fibroblasts. The binding characteristics of TDP-A to its target HDAC1 was examined using bioluminescence resonance energy transfer (BRET). Western blot and flow cytometry analysis showed that TDP-A induces cell cycle arrest and apoptosis in a dose-dependent manner. TDP-A dose-dependently activated the Notch pathway as measured by increasing functional CBF1-luciferase reporter signal and mRNA and protein expressions of Notch isoforms, which were attenuated by pretreatment with γ-secretase inhibitor DAPT. Furthermore, TDP-A lead to changes in expression level of downstream targets of Notch pathway and reduced expression of NE cancer markers. An in vivo study demonstrated that TDP-A suppressed NE cancer progression. These results show that TDP-A, as a Notch activator, is a promising agent against NE cancers.

A versatile nanoplatform for synergistic combination therapy to treat human esophageal cancer

One of the major goals of precision oncology is to promote combination therapy to improve efficacy and reduce side effects of anti-cancer drugs based on their molecular mechanisms. In this study, we aimed to develop and validate new nanoformulations of docetaxel (DTX) and bortezomib (BTZ) for targeted combination therapy to treat human esophageal cancer. By leveraging our versatile disulfide cross-linked micelles (DCMs) platform, we developed nanoformulations of DTX and BTZ (named DTX-DCMs and BTZ-DCMs). Their physical properties were characterized; their anti-cancer efficacies and mechanisms of action were investigated in a human esophageal cancer cell line in vitro. Furthermore, the in vitro anti-tumor activities of combination therapies (concurrent drug treatment, sequential drug treatment, and treatment using different ratios of the drugs) were examined in comparison with the single drug treatment and free drug strategies. These drug-loaded nanoparticles were spherical in shape and relatively small in size of approximately 20-22 nm. The entrapment efficiencies of DTX and BTZ into nanoparticles were 82.4% and 84.1%, respectively. The drug release rates of DTX-DCMs and BTZ-DCMs were sustained, and greatly increased in the presence of GSH. These nanodrugs were effectively internalized by KYSE30 esophageal cancer cells, and dose-dependently induced cell apoptosis. We further revealed a strong synergistic effect between DTX-DCMs and BTZ-DCMs against KYSE30 esophageal cancer cells. Sequential combination therapy with DTX-DCMs followed by BTZ-DCMs exhibited the best anti-tumor efficacy in vitro. This study demonstrates that DTX and BTZ could be successfully nanoformulated into disulfide cross-linked micelles. The nanoformulations of DTX and BTZ demonstrate an immense potential for synergistic combination therapy to treat human esophageal cancer.

Cholic acid-based novel micellar nanoplatform for delivering FDA-approved taxanes

AIM

To structurally modify our existing cholic acid (CA)-based telodendrimer (TD; PEG^5K-CA₈) for effective micellar nanoencapsulation and delivery of the US FDA-approved members of taxane family.

MATERIALS & METHODS

Generation of hybrid TDs was achieved by replacing four of the eight CAs with biocompatible organic moieties using solution-phase peptide synthesis. Drug loading was done using the standard evaporation method.

RESULTS

Hybrid TDs can generate micelles with narrow size distributions, low critical micelle concentration values (1-6 μM), better hematocompatibility and lack of in vitro cytotoxicity.

CONCLUSION

Along with PEG^5K-CA₈, CA-based hybrid nanoplatform is the first of its kind that can stably encapsulate all three FDA-approved taxanes with nearly 100% efficiency up to 20% (w/w) loading.

KE108-conjugated unimolecular micelles loaded with a novel HDAC inhibitor thailandepsin-A for targeted neuroendocrine cancer therapy

Neuroendocrine (NE) cancers can cause significant patient morbidity. Besides surgery, there are no curative treatments for NE cancers and their metastases, emphasizing the need for the development of other forms of therapy. In this study, multifunctional unimolecular micelles were developed for targeted NE cancer therapy. The unimolecular micelles were formed by multi-arm star amphiphilic block copolymer poly(amidoamine)-poly(valerolactone)-poly(ethylene glycol) conjugated with KE108 peptide and Cy5 dye (abbreviated as PAMAM-PVL-PEG-KE108/Cy5). The unimolecular micelles with a spherical core-shell structure exhibited a uniform size distribution and excellent stability. The hydrophobic drug thailandepsin-A (TDP-A), a recently discovered HDAC inhibitor, was physically encapsulated into the hydrophobic core of the micelles. KE108 peptide, a somatostatin analog possessing high affinity for all five subtypes of somatostatin receptors (SSTR 1-5), commonly overexpressed in NE cancer cells, was used for the first time as an NE cancer targeting ligand. KE108 exhibited superior targeting abilities compared to other common somatostatin analogs, such as octreotide, in NE cancer cell lines. The in vitro assays demonstrated that the TDP-A-loaded, KE108-targeted micelles exhibited the best capabilities in suppressing NE cancer cell growth. Moreover, the in vivo near-infrared fluorescence imaging on NE-tumor-bearing nude mice showed that KE108-conjugated micelles exhibited the greatest tumor accumulation due to their passive targeting and active targeting capabilities. Finally, TDP-A-loaded and KE108-conjugated micelles possessed the best anticancer efficacy without detectable systemic toxicity. Thus, these novel TDP-A-loaded and KE108-conjugated unimolecular micelles offer a promising approach for targeted NE cancer therapy.