Activated Charge-Reversal Polymeric Nano-System: The Promising Strategy in Drug Delivery for Cancer Therapy

Tailoring Gene Transfer Efficacy through the Arrangement of Cationic and Anionic Blocks in Triblock Copolymer Micelles

The arrangement of charged segments in triblock copolymer micelles affects the gene delivery potential of polymeric micelles and can increase the level of gene expression when an anionic segment is incorporated in the outer shell. Triblock copolymers were synthesized by RAFT polymerzation with narrow molar mass distributions and assembled into micelles with a hydrophobic core from poly(n-butyl acrylate). The ionic shell contained either (i) an anionic segment followed by a cationic segment (HAC micelles) or (ii) a cationic block followed by an anionic block (HCA micelles). The pH-responsive anionic block contained 2-carboxyethyl acrylamide (CEAm), while the cationic block comprised 3-guanidinopropyl acrylamide (GPAm). Increasing the molar content of CEAm in HAC and HCA micelles from 6 to 13 mol % improved cytocompatibility and the endosomal escape property, while the HCA micelle with the highest mol % of anionic charges in the outer shell exhibited the highest gene expression. It became evident that improved membrane interaction of the best performing HCA micelle contributed to achieving high gene expression.

Charge-Reversible Nanoparticles: Advanced Delivery Systems for Therapy and Diagnosis

The past two decades have witnessed a rapid progress in the development of surface charge-reversible nanoparticles (NPs) for drug delivery and diagnosis. These NPs are able to elegantly address the polycation dilemma. Converting their surface charge from negative/neutral to positive at the target site, they can substantially improve delivery of drugs and diagnostic agents. By specific stimuli like a shift in pH and redox potential, enzymes, or exogenous stimuli such as light or heat, charge reversal of NP surface can be achieved at the target site. The activated positive surface charge enhances the adhesion of NPs to target cells and facilitates cellular uptake, endosomal escape, and mitochondrial targeting. Because of these properties, the efficacy of incorporated drugs as well as the sensitivity of diagnostic agents can be essentially enhanced. Furthermore, charge-reversible NPs are shown to overcome the biofilm formed by pathogenic bacteria and to shuttle antibiotics directly to the cell membrane of these microorganisms. In this review, the up-to-date design of charge-reversible NPs and their emerging applications in drug delivery and diagnosis are highlighted.

Long-Term Vaccine Delivery and Immunological Responses Using Biodegradable Polymer-Based Carriers

Biodegradable polymers are largely employed in the biomedical field, ranging from tissue regeneration to drug/vaccine delivery. The biodegradable polymers are highly biocompatible and possess negligible toxicity. In addition, biomaterial-based vaccines possess adjuvant properties, thereby enhancing immune responses. This Review introduces the use of different biodegradable polymers and their degradation mechanism. Different kinds of vaccines, as well as the interaction between the carriers with the immune system, then are highlighted. Natural and synthetic biodegradable micro-/nanoplatforms, hydrogels, and scaffolds for local or targeted and controlled vaccine release are subsequently discussed.

Pancreatic tumor microenvironmental acidosis and hypoxia transform gold nanorods into cell-penetrant particles for potent radiosensitization

Coating nanoparticles with stealth epilayers increases circulation time by evading opsonization, macrophage phagocytosis, and reticuloendothelial sequestration. However, this also reduces internalization by cancer cells upon reaching the tumor. We designed gold nanorods (GNRs) with an epilayer that retains stealth properties in circulation but transforms spontaneously in the acidotic tumor microenvironment to a cell-penetrating particle. We used a customized stoichiometric ratio of l-glutamic acid and l-lysine within an amphiphilic polymer of poly(l-glutamic acid-co-l-lysine), or P(Glu-co-Lys), to effect this transformation in acidotic environments. P(Glu-co-Lys)-GNRs were internalized by cancer cells to facilitate potent in vitro radiosensitization. When administered intravenously in mice, they accumulate in the periphery and core of tumors without any signs of serum biochemical or hematological alterations, normal organ histopathological abnormalities, or overt deterioration in animal health. Furthermore, P(Glu-co-Lys)-GNRs penetrated the tumor microenvironment to accumulate in the hypoxic cores of tumors to potently radiosensitize heterotopic and orthotopic pancreatic cancers in vivo.

Delivery process and effective design of vectors for cancer therapy

In recent years, the efficacy of nano-drugs has not been significantly better than that of the drugs themselves, mainly because nano-drugs enter the tumor vasculature, stay near the blood vessels, and cannot enter the tumor tissues or tumor cells to complete the drug delivery process. Although intratumor injection can significantly decrease this risk, the side effects are strong. The advent of drug delivery carrier materials offers an opportunity to avoid the side effects of systemic drug delivery and the damage caused by tumor resection, holding great promise for the future of cancer therapy. Here, we systematically review recent research advances in the classification of drug delivery carrier materials and the delivery process in drug delivery systems. This review is divided into several main sections, first, we summarize the classification of tumor drug carrier materials, including drug delivery vectors and gene delivery vectors, etc., which are introduced in detail, respectively. Then we describe the carrier materials to deliver the drug cascade and the transition pathways for drug delivery, including stabilization transitions, charge inversions, and size changes. Finally, we discuss the current design strategies and research progress of drug vectors and provide a summary and outlook. This review aims to summarize different drug delivery vehicles and delivery processes to provide ideas for effective cancer therapy.

Nucleic acid strategies for infectious disease treatments: The nanoparticle-based oral delivery route

Therapies based on orally administrated nucleic acids have significant potential for the treatment of infectious diseases, including chronic inflammatory diseases such as inflammatory bowel disease (IBD)-associated with the gastrointestinal (GI) tract, and infectious and acute contagious diseases like coronavirus disease 2019 (COVID-19). This is because nucleic acids could precisely regulate susceptibility genes in regulating the pro- and anti-inflammatory cytokines expression related to the infections. Unfortunately, gene delivery remains a major hurdle due to multiple intracellular and extracellular barriers. This review thoroughly discusses the challenges of nanoparticle-based nucleic acid gene deliveries and strategies for overcoming delivery barriers to the inflammatory sites. Oral nucleic acid delivery case studies were also present as vital examples of applications in infectious diseases such as IBD and COVID-19.

Biomedical Applications of polymeric micelles in the treatment of diabetes mellitus: Current success and future approaches

INTRODUCTION

Diabetes mellitus (DM) is the most common metabolic disease and multifactorial, harming patients worldwide. Extensive research has been carried out in the search for novel drug delivery systems offering reliable control of glucose levels for diabetics, aiming at efficient management of DM.

AREAS COVERED

Polymeric micelles (PMs) as smart drug delivery nanocarriers are discussed, focusing on oral drug delivery applications for the management of hyperglycemia. The most recent approaches used for the preparation of smart PMs employ molecular features of amphiphilic block copolymers (ABCs), such as stimulus sensitivity, ligand conjugation, and as a more specific example the ability to inhibit islet amyloidosis.

EXPERT OPINION

PMs provide a unique platform for self-regulated or spatiotemporal drug delivery, mimicking the working mode of pancreatic islets to maintain glucose homeostasis for prolonged periods. This unique characteristic is achieved by tailoring the functional chemistry of ABCs considering the physicochemical traits of PMs, including sensing capabilities, hydrophobicity, etc. In addition, the application of ABCs for the inhibition of conformational changes in islet amyloid polypeptide garnered attention as one of the root causes of DM. However, research in this field is limited and further studies at the clinical level are required.

Anti-tumor effect of liposomes containing extracted Murrayafoline A against liver cancer cells in 2D and 3D cultured models

Murrayafoline A (MuA) is a natural compound with diverse biological activities, including cytotoxicity against cancer cells, but suffers from poor water solubility and low specificity. In order to improve the potential of MuA as a candidate for cancer treatment, MuA-loaded liposomes were prepared with the liposomal membrane consisting of dioleoylphosphatidylcholine and cholesterol. Dynamic light scattering measurements showed that the MuA-loaded liposomes had a z-average particle size of 104.3 ± 6.4 nm (mean ± SD; n = 3) and a polydispersity index of 0.15 ± 0.02 (mean ± SD; n = 3). The encapsulation efficiency was 55.3 ± 2.3% (mean ± SD; n = 3). The in vitro cytotoxicity of encapsulated MuA was attenuated at IC50 = 21.97 µg/mL compared to 6.24 µg/mL for free MuA, against HepG2. In contrast, MuA-loaded liposomes were significantly more effective at inhibiting cell growth in HepG2 cancer spheroids, which indicated that they were able to reach the interior layers of the microtumor. Taken together, these results showed that the encapsulation of MuA in liposomes is a good research direction to improve this natural compound’s potential as a candidate for cancer treatment.

Multiple targeted doxorubicin-lonidamine liposomes modified with p-hydroxybenzoic acid and triphenylphosphonium to synergistically treat glioma

A type of pH-sensitive multi-targeted brain tumor site-specific liposomes (Lip-CTPP) co-modified with p-hydroxybenzoic acid (p-HA) and triphenylphosphonium (TPP) were designed and prepared to co-load doxorubicin (DOX) and lonidamine (LND). Lip-CTPP are promising potential carriers to exert the anti-glioma effect of DOX and LND collaboratively given the following features: 1) Lip-CTPP have a good pharmacokinetic behavior; 2) Lip-CTPP can cross the blood-brain barrier (BBB) and recognize tumor cells through the affinity of p-HA and dopamine/sigma receptors; 3) Lip-CTPP are highly positive charged once the acid-sensitive amide bonds are cleaved in endo/lysosomes to expose TPP and protonate amine groups; 4) the positive charged Lip-CTPP escape from endo/lysosomes and accumulate in mitochondria through electrostatic adsorption; 5) DOX and LND are released and synergistically increase anti-tumor efficacy. Our in vitro and in vivo results confirmed that Lip-CTPP could greatly elevate the inhibition rate of tumor cell proliferation, migration and invasion, promote apoptosis and necrosis, and interfere with mitochondrial function. In addition, Lip-CTPP could significantly prolong the survival time of glioma bearing mice, narrow the tumor region and inhibit the infiltration and metastasis capability of glioma cells. Collectively, Lip-CTPP are promising nano formulations to enhance the synergistic effect of DOX and LND in glioma treatment.

The Use of Nanomedicine to Target Signaling by the PAK Kinases for Disease Treatment

P21-activated kinases (PAKs) are serine/threonine kinases involved in the regulation of cell survival, proliferation, inhibition of apoptosis, and the regulation of cell morphology. Some members of the PAK family are highly expressed in several types of cancer, and they have also been implicated in several other medical disorders. They are thus considered to be good targets for treatment of cancer and other diseases. Although there are several inhibitors of the PAKs, the utility of some of these inhibitors is reduced for several reasons, including limited metabolic stability. One way to overcome this problem is the use of nanoparticles, which have the potential to increase drug delivery. The overall goals of this review are to describe the roles for PAK kinases in cell signaling and disease, and to describe how the use of nanomedicine is a promising new method for administering PAK inhibitors for the purpose of disease treatment and research. We discuss some of the basic mechanisms behind nanomedicine technology, and we then describe how these techniques are being used to package and deliver PAK inhibitors.

Current trends and future perspectives of nanomedicine for the management of colon cancer

Colon cancer (CC) kills countless people every year throughout the globe. It persists as one of the highly lethal diseases to be treated because the overall survival rate for CC is meagre. Early diagnosis and efficient treatments are two of the biggest hurdles in the fight against cancer. In the present work, we will review thriving strategies for CC targeted drug delivery and critically explain the most recent progressions on emerging novel nanotechnology-based drug delivery systems. Nanotechnology-based animal and human clinical trial studies targeting CC are discussed. Advancements in nanotechnology-based drug delivery systems intended to enhance cellular uptake, improved pharmacokinetics and effectiveness of anticancer drugs have facilitated the powerful targeting of specific agents for CC therapy. This review provides insight into current progress and future opportunities for nanomedicines as potential curative targets for CC treatment. This information could be used as a platform for the future expansion of multi-functional nano constructs for CC's advanced detection and functional drug delivery.

In vitro/vivo antitumor study of modified-chitosan/carboxymethyl chitosan "boosted" charge-reversal nanoformulation

Major obstacles in the development of nanoformulations as efficient drug delivery systems are the rapid clearance from blood circulation and lysosomal entrapment. To overcome these problems, a polysaccharide-based core-shell type charge-switchable nanoformulation (CS-LA-DMMA/CMCS/PAMAM@DOX) is constructed to improve antitumor efficacy of DOX. By applying carboxymethyl chitosan (CMCS) as bridge polymer and negatively charged chitosan-derivative as outer shell, the stability and pH-sensitivity of this nanoformulation is promisingly enhanced. Furthermore, the positively charged PAMAM@DOX could escape from lysosomes via "proton sponge effect" and "cationic-anionic interaction with lysosome membranes". Admirable cellular uptake and high apoptosis/necrosis rate were detected in this study. In vitro assays demonstrate that the CS-LA-DMMA/CMCS/PAMAM@DOX was internalized into HepG2 cells predominantly via the clathrin-mediated endocytosis pathway. Excitingly, in vivo studies showed that high accumulation of CS-LA-DMMA/CMCS/PAMAM@DOX in tumor tissue led to enhanced tumor inhibition. Compared with free DOX, the tumor inhibition rate of nanoformulation was improved up to 226%.

Precise Controlled Target Molecule Release through Light-Triggered Charge Reversal Bridged Polysilsesquioxane Nanoparticles

Precise control of target molecule release time, site, and dosage remains a challenge in controlled release systems. We employed a photoresponsive molecule release system via light-triggered charge reversal nanoparticles to achieve a triggered, stepwise, and precise controlled release platform. This release system was based on photocleavage-bridged polysilsesquioxane nanoparticles which acted as nanocarriers of doxorubicin loaded on the surface via electrostatic interaction. The nanoparticles could reverse into positive charges triggered by 254 nm light irradiation due to the photocleavage of the o-nitrobenzyl bridged segment. The charge reversal property of the nanoparticles could release loaded molecules. Doxorubicin was selected as a positively charged model molecule. The as-prepared nanoparticles with an average size of 124 nm had an acceptable doxorubicin loading content up to 12.8%. The surface charge of the nanoparticles could rapidly reverse from negative (−28.20 mV) to positive (+18.9 mV) upon light irradiation for only 10 min. In vitro release experiments showed a cumulative release up to 96% with continuously enhancing irradiation intensity. By regulating irradiation parameters, precisely controlled drug release was carried out. The typical “stepped” profile could be accurately controlled in an on/off irradiation mode. This approach provides an ideal light-triggered molecule release system for location, timing, and dosage. This updated controlled release system, triggered by near-infrared or infrared light, will have greater potential applications in biomedical technology.

Nanoformulations of Ursolic Acid: A Modern Natural Anticancer Molecule

Background: Ursolic acid (UA) is a natural pentacyclic triterpene derived from fruit, herb, and other plants. UA can act on molecular targets of various signaling pathways, inhibit the growth of cancer cells, promote cycle stagnation, and induce apoptosis, thereby exerting anticancer activity. However, its poor water-solubility, low intestinal mucosal absorption, and low bioavailability restrict its clinical application. In order to overcome these deficiencies, nanotechnology, has been applied to the pharmacological study of UA.

Objective: In this review, we focused on the absorption, distribution, and elimination pharmacokinetics of UA in vivo, as well as on the research progress in various UA nanoformulations, in the hope of providing reference information for the research on the anticancer activity of UA.

Methods: Relevant research articles on Pubmed and Web of Science in recent years were searched selectively by using the keywords and subheadings, and were summarized systematically.

Key finding: The improvement of the antitumor ability of the UA nanoformulations is mainly due to the improvement of the bioavailability and the enhancement of the targeting ability of the UA molecules. UA nanoformulations can even be combined with computational imaging technology for monitoring or diagnosis.

Conclusion: Currently, a variety of UA nanoformulations, such as micelles, liposomes, and nanoparticles, which can increase the solubility and bioactivity of UA, while promoting the accumulation of UA in tumor tissues, have been prepared. Although the research of UA in the nanofield has made great progress, there is still a long way to go before the clinical application of UA nanoformulations.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Harnessing amphiphilic polymeric micelles for diagnostic and therapeutic applications: Breakthroughs and bottlenecks

Amphiphilic block copolymers are widely utilized in the design of formulations owing to their unique physicochemical properties, flexible structures and functional chemistry. Amphiphilic polymeric micelles (APMs) formed from such copolymers have gained attention of the drug delivery scientists in past few decades for enhancing the bioavailability of lipophilic drugs, molecular targeting, sustained release, stimuli-responsive properties, enhanced therapeutic efficacy and reducing drug associated toxicity. Their properties including ease of surface modification, high surface area, small size, and enhanced permeation as well as retention (EPR) effect are mainly responsible for their utilization in the diagnosis and therapy of various diseases. However, some of the challenges associated with their use are premature drug release, low drug loading capacity, scale-up issues and their poor stability that need to be addressed for their wider clinical utility and commercialization. This review describes comprehensively their physicochemical properties, various methods of preparation, limitations followed by approaches employed for the development of optimized APMs, the impact of each preparation technique on the physicochemical properties of the resulting APMs as well as various biomedical applications of APMs. Based on the current scenario of their use in treatment and diagnosis of diseases, the directions in which future studies need to be carried out to explore their full potential are also discussed.

A Sequentially Responsive Nanosystem Breaches Cascaded Bio-barriers and Suppresses P-Glycoprotein Function for Reversing Cancer Drug Resistance

Cancer chemotherapy is challenged by multidrug resistance (MDR) mainly attributed to overexpressed transmembrane efflux pump P-glycoprotein (P-gp) in cancer cells. Improving drug delivery efficacy while co-delivering P-gp inhibitors to suppress drug efflux is an often-used nanostrategy for combating MDR, which is however challenged by cascaded bio-barriers en route to cancer cells and P-gp inhibitors' adverse effects. To effectively breach the cascaded bio-barriers while avoiding P-gp inhibitors' adverse effects, a stealthy, sequentially responsive doxorubicin (DOX) delivery nanosystem (RCMSNs) is fabricated, composed of an extracellular-tumor-acidity-responsive polymer shell (PEG-b-PLLDA), pH/redox dual-responsive mesoporous silica nanoparticle-based carriers (MSNs-SS-Py), and cationic β-cyclodextrin-PEI (CD-PEI) gatekeepers. The PEG-b-PLLDA corona makes RCMSNs stealthy with prolonged blood circulation time. Once tumors are reached, extracellular acidity degrades PEG-b-PLLDA, reversing nanosystem's surface charges to be positive, which drastically improves RCMSNs' tumor accumulation, penetration, and cellular internalization. Within cancer cells, CD-PEI gatekeepers detach to allow DOX unloading in response to intracellular acidity and glutathione and functionally act as a P-gp inhibitor, dampening P-gp's efflux activity by impairing ATP production. Thus, the resultant high-efficacy drug delivery along with reduced P-gp function cooperatively reverses MDR in vitro. Importantly, in preclinical tumor models, DOX@RCMSNs potently suppress MDR tumor growth without eliciting systemic toxicity, demonstrating their potential of clinical translation.

Triphenylphosphonium-conjugated glycol chitosan microspheres for mitochondria-targeted drug delivery

To develop an efficient vector for mitochondria-targeted drug delivery, we synthesized triphenylphosphonium (TPP)-modified glycol chitosan polymeric microspheres that had a unique chemical structure with both lipophilic phenyl groups and cationic phosphonium. Notably, TPP can easily pass through the phospholipid bilayer of mitochondria, thereby resulting in specific accumulation of a combined drug molecule in the mitochondria due to the membrane potential between TPP and its membrane. Therefore, TPP has been widely used as a mitochondria-targeting moiety. Triphenylphosphonium-glycol chitosan derivatives (GC-TPP and GME-TPP) with two different degrees of substitution (11% and 36%) were prepared by amidation and Michael addition. The chemical structures of GC-TPP and GME-TPP were characterized by ¹H nuclear magnetic resonance and Fourier-transform infrared spectroscopy, and their sizes were measured via field emission scanning electron microscopy and dynamic light scattering. Cellular uptake through flow cytometric analysis and confocal microscopy confirmed that both GC-TPP and GME-TPP were well introduced into cells, targeting the mitochondria. In addition, cytotoxicity testing of the most common cell lines, such as HEK293, HeLa, NIH3T3, and HepG2, indicated the absence of polymer toxicity. To evaluate the carrier effectiveness of TPP for drug delivery, doxorubicin (Dox) was used as an anticancer drug. Confocal microscopy images showed that Dox-loaded GME-TPP accumulated inside cells more than Dox-loaded GC-TPP. The anticancer effects of Dox were also determined by MTT assay, apoptosis/necrosis assay, and three-dimensional spheroids. In summary, the results indicate that GC-TPP and GME-TPP microspheres possess great potential as effective drug delivery carriers.

A pH-Sensitive Self-Assembled and Carrier-Free Nanoparticle Based on Charge Reversal for Enhanced Synergetic Chemo-Phototherapy

To overcome biological barriers for nanoparticles (NPs) efficaciously accumulated at tumor sites, as well as enhancing the performance of drug delivery systems, a carrier-free nanoparticle based on charge reversal is designed for improved synergetic chemo-phototherapy for cancer treatment. In this system, doxorubicin (Dox) and zinc phthalocyanine (ZnPc) are self-assembled through noncovalent interactions (π-π stacking, hydrophobic forces) to avoid the possible toxicity of excipient, complex chemical conjugations and batch-to-batch variation. A trace amount of poly(2-(di-methylamino) ethylmethacrylate)- poly[(R)-3-hydroxybutyrate]- poly(2-(dimethylamino) ethylmethacrylate (PDMAEMA-PHB-PDMAEMA) is modified on the surface of Dox-ZnPc to construct the novel nanoparticles, namely DZP, with long-term stability, and with a dual-drug load content of up to ≈90％. The drug delivery system (DDS) can effectively decrease its toxicity among physical circulation and increase the accumulation at the tumor site. Moreover, the developed DZP nanoparticles show excellent photo-chemotherapy, photoacoustic (PA) and fluorescence (FL) imaging characteristics for multimodal imaging-guided synergetic therapy.

The In Vitro, Ex Vivo, and In Vivo Effect of Polymer Hydrophobicity on Charge-Reversible Vectors for Self-Amplifying RNA

RNA technology has the potential to revolutionize vaccination. However, the lack of clear structure-property relationships in relevant biological models mean there is no clear consensus on the chemical motifs necessary to improve RNA delivery. In this work, we describe the synthesis of a series of copolymers based on the self-hydrolyzing charge-reversible polycation poly(dimethylaminoethyl acrylate) (pDMAEA), varying the lipophilicity of the additional co-monomers. All copolymers formed stable polyplexes, showing efficient complexation with model nucleic acids from nitrogen/phosphate (N/P) ratios of N/P = 5, with more hydrophobic complexes exhibiting slower charge reversal and disassembly compared to hydrophilic analogues. The more hydrophobic copolymers outperformed hydrophilic versions, homopolymer controls and the reference standard polymer (polyethylenimine), in transfection assays on 2D cell monolayers, albeit with significantly higher toxicities. Similarly, hydrophobic derivatives displayed up to a 4-fold higher efficacy in terms of the numbers of cells expressing green fluorescent protein (GFP⁺) cells in ex vivo human skin (10%) compared to free RNA (2%), attributed to transfection enrichment in epithelial cells. In contrast, in a mouse model, we observed the reverse trend in terms of RNA transfection, with no observable protein production in more hydrophobic analogues, whereas hydrophilic copolymers induced the highest transfection in vivo. Overall, our results suggest an important relationship between the vector lipophilicity and RNA transfection in vaccine settings, with polymer biocompatibility potentially a key parameter in effective in vivo protein production.

Targeting Mutant KRAS for Anticancer Therapy

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Over the past decades, designing therapeutic strategies to target KRAS-mutant cancers, which is one of the most frequent mutant oncogenes among all cancer types, have proven unsuccessful regardless of many concerted attempts. There are key challenges for KRAS-mutant anticancer therapy, as the complex cellular processes involved in KRAS signaling has present. Herein, we highlight the emerging therapeutic approaches for inhibiting KRAS signaling and blocking KRAS functions, in hope to serve as a more effective guideline for future development of therapeutics.

Rational Design of Cancer Nanomedicine for Simultaneous Stealth Surface and Enhanced Cellular Uptake

Owing to the complex and still not fully understood physiological environment, the development of traditional nanosized drug delivery systems is very challenging for precision cancer therapy. It is very difficult to control the in vivo distribution of nanoparticles after intravenous injection. The ideal drug nanocarriers should not only have stealth surface for prolonged circulation time but also possess enhanced cellular internalization in tumor sites. Unfortunately, the stealth surface and enhanced cellular uptake seem contradictory to each other. How to integrate the two opposite aspects into one system is a very herculean but meaningful task. As an alternative drug delivery strategy, chameleon-like drug delivery systems were developed to achieve long circulation time while maintaining enhanced cancer cell uptake. Such drug nanocarriers can "turn off" their internalization ability during circulation. However, the enhanced cellular uptake can be readily activated upon arriving at tumor tissues. In this way, stealth surface and enhanced uptake are of dialectical unity in drug delivery. In this review, we focus on the surface engineering of drug nanocarriers to obtain simultaneous stealth surfaces in circulation and enhanced uptake in tumors. The current strategies and ongoing developments, including programmed tumor-targeting strategies and some specific zwitterionic surfaces, will be discussed in detail.

Nanocarrier-Mediated Chemo-Immunotherapy Arrested Cancer Progression and Induced Tumor Dormancy in Desmoplastic Melanoma

In desmoplastic melanoma, tumor cells and tumor-associated fibroblasts are the major dominators playing a critical role in the fibrosis morphology as well as the immunosuppressive tumor microenvironment (TME), compromising the efficacy of therapeutic options. To overcome this therapeutic hurdle, we developed an innovative chemo-immunostrategy based on targeted delivery of mitoxantrone (MIT) and celastrol (CEL), two potent medicines screened and selected with the best anticancer and antifibrosis potentials. Importantly, CEL worked in synergy with MIT to induce immunogenic tumor cell death. Here, we show that when effectively co-delivered to the tumor site at their optimal ratio by a TME-responsive nanocarrier, the 5:1 combination of MIT and CEL significantly triggered immunogenic tumor apoptosis and recovered tumor antigen recognition, thus eliciting overall antitumor immunity. Furthermore, the strong synergy benefitted the host in reduced drug exposure and side effects. Collectively, the nanocarrier-mediated chemo-immunotherapy successfully remodeled fibrotic and immunosuppressive TME, arrested cancer progression, and further inhibited tumor metastasis to major organs. The affected tumors remained dormant long after dosing stopped, resulting in a prolonged progression-free survival and sustained immune surveillance of the host bearing desmoplastic melanoma.

Targeted delivery and release of doxorubicin using a pH-responsive and self-assembling copolymer

We developed a pH-response copolymer that entrapped DOX into its hydrophobic core and self-assembles into smart DOX-loaded nanoparticles, which could enhance cancer-targeting and effective drug release in tumors.