A redox-sensitive, oligopeptide-guided, self-assembling, and efficiency-enhanced (ROSE) system for functional delivery of microRNA therapeutics for treatment of hepatocellular carcinoma

Multifunctional and stimuli-responsive liposomes in hepatocellular carcinoma diagnosis and therapy

Hepatocellular carcinoma (HCC) is the most prevalent type of liver cancer, mainly occurring in Asian countries with an increased incidence rate globally. Currently, several kinds of therapies have been deployed for HCC therapy including surgical resection, chemotherapy, radiotherapy and immunotherapy. However, this tumor is still incurable, requiring novel strategies for its treatment. The nanomedicine has provided the new insights regarding the treatment of cancer that liposomes as lipid-based nanoparticles, have been widely applied in cancer therapy due to their biocompaitiblity, high drug loading and ease of synthesis and modification. The current review evaluates the application of liposomes for the HCC therapy. The drugs and genes lack targeting ability into tumor tissues and cells. Therefore, loading drugs or genes on liposomes can increase their accumulation in tumor site for HCC suppression. Moreover, the stimuli-responsive liposomes including pH-, redox- and light-sensitive liposomes are able to deliver drug into tumor microenvironment to improve therapeutic index. Since a number of receptors upregulate on HCC cells, the functionalization of liposomes with lactoferrin and peptides can promote the targeting ability towards HCC cells. Moreover, phototherapy can be induced by liposomes through loading phtoosensitizers to stimulate photothermal- and photodynamic-driven ablation of HCC cells. Overall, the findings are in line with the fact that liposomes are promising nanocarriers for the treatment of HCC.

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

miRNAs are now starring in "No Time to Die: Overcoming the chemoresistance in cancer"

Cancer is a leading cause of death globally, with about 19.3 million new cases reported each year. Current therapies for cancer management include-chemotherapy, radiotherapy, and surgery. However, they are loaded with side effects and tend to cause toxicity in the patient's body posttreatment, ultimately hindering the response towards the treatment building up resistance. This is where noncoding RNAs such as miRNAs help provide us with a helping hand for taming the chemoresistance and providing potential holistic cancer management. MicroRNAs are promising targets for anticancer therapy as they perform critical regulatory roles in various signaling cascades related to cell proliferation, apoptosis, migration, and invasion. Combining miRNAs and anticancer drugs and devising a combination therapy has managed cancer well in various independent studies. This review aims to provide insights into how miRNAs play a mechanistic role in cancer development and progression and regulate drug resistance in various types of cancers. Furthermore, next-generation novel therapies using miRNAs in combination with anticancer treatments in multiple cancers have been put forth and how they improve the efficacy of the treatments. Exemplary studies currently in the preclinical and clinical models have been summarized. Ultimately, we briefly talk through the challenges that come forward with it and minimize them.

Perspectives of using microRNA-loaded nanocarriers for epigenetic reprogramming of drug resistant colorectal cancers

Epigenetic regulation by microRNAs (miRs) demonstrated a promising therapeutic potential of these molecules to regulate genetic activity in different cancers, including colorectal cancers (CRCs). The RNA-based therapy does not change genetic codes in tumor cells but can silence oncogenes and/or reactivate inhibited tumor suppressor genes. In many cancers, specific miRs were shown to promote or stop tumor progression. Among confirmed and powerful epigenetic regulators of colon carcinogenesis and development of resistance are onco-miRs, which include let-7, miR-21, miR-22, miR-23a, miR-27a, miR-34, miR-92, miR-96, miR-125b, miR-135b, miR-182, miR-200c, miR-203, miR-221, miR-421, miR-451, and others. Moreover, various tumor-suppressor miRs (miR-15b-5b, miR-18a, miR-20b, miR-22, miR-96, miR-139-5p, miR-145, miR-149, miR-197, miR-199b, miR-203, miR-214, miR-218, miR-320, miR-375-3p, miR-409-3p, miR-450b-5p, miR-494, miR-577, miR-874, and others) were found silenced in drug-resistant CRCs. Re-expression of tumor suppressor miR is complicated by the chemical nature of miRs that are not long-lasting compounds and require protection from the enzymatic degradation. Several recent studies explored application of miRs using nanocarrier complexes. This study critically describes the most successfully tested nanoparticle complexes used for intracellular delivery of nuclear acids and miRs, including micelles, liposomes, inorganic and polymeric NPs, dendrimers, and aptamers. Nanocarriers shield incorporated miRs and improve the agent stability in circulation. Attachment of antibodies and/or specific peptide or ligands facilitates cell-targeted miR delivery. Addressing in vivo challenges, a broad spectrum of non-toxic materials has been tested and indicated reliable advantages of lipid-based (lipoplexes) and polymer-based liposomes. Recent cutting-edge developments indicated that lipid-based complexes with multiple cargo, including several miRs, are the most effective approach to eradicate drug-resistant tumors. Focusing on CRC-specific miRs, this review provides a guidance and insights towards the most promising direction to achieve dramatic reduction in tumor growth and metastasis using miR-nanocarrier complexes.

Intercellular communication in the tumour microecosystem: Mediators and therapeutic approaches for hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most common tumours worldwide, is one of the main causes of mortality in cancer patients. There are still numerous problems hindering its early diagnosis, which lead to late patients receiving treatment, and these problems need to be solved urgently. The tumour microecosystem is a complex network system comprising seven parts: the hypoxia niche, immune microenvironment, metabolic microenvironment, acidic niche, innervated niche, mechanical microenvironment, and microbial microenvironment. Intercellular communication is divided into direct contact and indirect communication. Direct contact communication includes gap junctions, tunneling nanotubes, and receptor-ligand interactions, whereas indirect communication includes exosomes, apoptotic vesicles, and soluble factors. Mechanical communication and cytoplasmic exchange are further means of intercellular communication. Intercellular communication mediates the crosstalk between the tumour microecosystem and the host as well as that between cells and cell-free components in the tumour microecosystem, causing changes in the tumour hallmarks of the HCC microecosystem such as changes in tumour proliferation, invasion, apoptosis, angiogenesis, metastasis, inflammatory response, gene mutation, immune escape, metabolic reprogramming, and therapeutic resistance. Here, we review the role of the above-mentioned intercellular communication in the HCC microecosystem and discuss the advantages of targeted intercellular communication in the clinical diagnosis and treatment of HCC. Finally, the current problems and prospects are discussed.

Drug Delivery Systems with a "Tumor-Triggered" Targeting or Intracellular Drug Release Property Based on DePEGylation

Coating nanosized anticancer drug delivery systems (DDSs) with poly(ethylene glycol) (PEG), the so-called PEGylation, has been proven an effective method to enhance hydrophilicity, aqueous dispersivity, and stability of DDSs. What is more, as PEG has the lowest level of protein absorption of any known polymer, PEGylation can reduce the clearance of DDSs by the mononuclear phagocyte system (MPS) and prolong their blood circulation time in vivo. However, the "stealthy" characteristic of PEG also diminishes the uptake of DDSs by cancer cells, which may reduce drug utilization. Therefore, dynamic protection strategies have been widely researched in the past years. Coating DDSs with PEG through dynamic covalent or noncovalent bonds that are stable in blood and normal tissues, but can be broken in the tumor microenvironment (TME), can achieve a DePEGylation-based "tumor-triggered" targeting or intracellular drug release, which can effectively improve the utilization of drugs and reduce their side effects. In this review, the stimuli and methods of "tumor-triggered" targeting or intracellular drug release, based on DePEGylation, are summarized. Additionally, the targeting and intracellular controlled release behaviors of the DDSs are briefly introduced.

MicroRNAs and Their Big Therapeutic Impacts: Delivery Strategies for Cancer Intervention

Three decades have passed from the initial discovery of a microRNA (miRNA) in Caenorhabditis elegans to our current understanding that miRNAs play essential roles in regulating fundamental physiological processes and that their dysregulation can lead to many human pathologies, including cancer. In effect, restoration of miRNA expression or downregulation of aberrantly expressed miRNAs using miRNA mimics or anti-miRNA inhibitors (anti-miRs/antimiRs), respectively, continues to show therapeutic potential for the treatment of cancer. Although the manipulation of miRNA expression presents a promising therapeutic strategy for cancer treatment, it is predominantly reliant on nucleic acid-based molecules for their application, which introduces an array of hurdles, with respect to in vivo delivery. Because naked nucleic acids are quickly degraded and/or removed from the body, they require delivery vectors that can help overcome the many barriers presented upon their administration into the bloodstream. As such, in this review, we discuss the strengths and weaknesses of the current state-of-the-art delivery systems, encompassing viral- and nonviral-based systems, with a specific focus on nonviral nanotechnology-based miRNA delivery platforms, including lipid-, polymer-, inorganic-, and extracellular vesicle-based delivery strategies. Moreover, we also shed light on peptide carriers as an emerging technology that shows great promise in being a highly efficacious delivery platform for miRNA-based cancer therapeutics.

Hepatocellular carcinoma, hepatitis C virus infection and miRNA involvement: Perspectives for new therapeutic approaches

Chronic hepatitis C virus (HCV) infection is the principal etiology of cirrhosis and, ultimately, hepatocellular carcinoma (HCC). At present, approximately 71 million people are chronically infected with HCV, and 10%-20% of these are expected to develop severe liver complications throughout their lifetime. Scientific evidence has clearly shown the causal association between miRNAs, HCV infection and HCC. Although it is not completely clear whether miRNA dysregulation in HCC is the cause or the consequence of its development, variations in miRNA patterns have been described in different liver diseases, including HCC. Many studies have analyzed the importance of circulating miRNAs and their effect on cell proliferation and apoptosis. In this Review, we aim to summarize current knowledge on the association between miRNA, HCV and HCC from a diagnostic point of view, and also the potential implications for therapeutic approaches.

A combined miR-34a and arsenic trioxide nanodrug delivery system for synergistic inhibition of HCC progression after microwave ablation

Background

Microwave ablation (MWA) has become an alternative treatment for unresectable hepatocellular carcinoma (HCC), but it does not eliminate the risk of recurrence and metastasis after treatment. Recent studies have demonstrated that miR-34a presents decreased gene expression in residual tumours after ablation therapy and can increase the therapeutic effect of arsenic trioxide against HCC, which brings new opportunities for HCC treatment.

Methods

A pH-sensitive charge inversion material was used to construct a nanotargeted delivery system based on the synergistic effects of miR-34a and As2O3. We established in vitro and in vivo models of HCC microwave ablation and performed in-depth research on the dual-drug system to inhibit the rapid progression and induce pyroptosis in HCC cells after microwave ablation.

Results

The antitumour effects were enhanced with the dual-drug nanoparticles relative to the single-drug formulations, and the therapeutic efficacy of the nanoparticles was more significant in a weakly acidic environment. The dual-drug nanoparticles increased the N-terminal portion of GSDME and decreased the expression of Cyt-c and c-met.

Conclusions

Dual-drug nanoparticles may improve the therapeutic efficacy of HCC treatment after insufficient ablation through Cyt-c and GSDME-N and decrease the expression levels of c-met. These nanoparticles are expected to provide new treatment methods for residual HCC after MWA, prolong the survival of patients and improve their quality of life.

Peptide-Assisted Nucleic Acid Delivery Systems on the Rise

Concerns associated with nanocarriers' therapeutic efficacy and side effects have led to the development of strategies to advance them into targeted and responsive delivery systems. Owing to their bioactivity and biocompatibility, peptides play a key role in these strategies and, thus, have been extensively studied in nanomedicine. Peptide-based nanocarriers, in particular, have burgeoned with advances in purely peptidic structures and in combinations of peptides, both native and modified, with polymers, lipids, and inorganic nanoparticles. In this review, we summarize advances on peptides promoting gene delivery systems. The efficacy of nucleic acid therapies largely depends on cell internalization and the delivery to subcellular organelles. Hence, the review focuses on nanocarriers where peptides are pivotal in ferrying nucleic acids to their site of action, with a special emphasis on peptides that assist anionic, water-soluble nucleic acids in crossing the membrane barriers they encounter on their way to efficient function. In a second part, we address how peptides advance nanoassembly delivery tools, such that they navigate delivery barriers and release their nucleic acid cargo at specific sites in a controlled fashion.

Cyclodextrins in drug delivery: applications in gene and combination therapy

Gene therapy is a powerful tool against genetic disorders and cancer, targeting the source of the disease rather than just treating the symptoms. While much of the initial success of gene delivery relied on viral vectors, non-viral vectors are emerging as promising gene delivery systems for efficacious treatment with decreased toxicity concerns. However, the delivery of genetic material is still challenging, and there is a need for vectors with enhanced targeting, reduced toxicity, and controlled release. In this article, we highlight current work in gene therapy which utilizes the cyclic oligosaccharide molecule cyclodextrin (CD). With a number of unique abilities, such as hosting small molecule drugs, acting as a linker or modular component, reducing immunogenicity, and disrupting membranes, CD is a valuable constituent in many delivery systems. These carriers also demonstrate great promise in combination therapies, due to the ease of assembling macromolecular structures and wide variety of chemical derivatives, which allow for customizable delivery systems and co-delivery of therapeutics. The use of combination and personalized therapies can result in improved patient health-modular systems, such as those which incorporate CD, are more conducive to these therapy types. Graphical abstract.

Therapeutic strategies for miRNA delivery to reduce hepatocellular carcinoma

Malignancies of hepatocellular carcinoma (HCC) are rapidly spreading and commonly fatal. Like most cancers, the gene expression patterns in HCC vary significantly from patient to patient. Moreover, the expression networks during HCC progression are largely controlled by microRNAs (miRNAs) regulating multiple oncogenes and tumor supressors. Therefore, miRNA-based therapeutic strategies altering these networks may significantly influence the cellular behavior enough for them to cure HCC. However, the most substantial challenges in developing such therapies are the stability of the oligos themselves and that of their delivery systems. Here we provide a comprehensive update describing various miRNA delivery systems, including virus-based delivery and non-viral delivery. The latter may be achieved using inorganic nanoparticles, polymer based nano-carriers, lipid-based vesicles, exosomes, and liposomes. Leaky vasculature in HCC-afflicted livers helps untargeted nanocarriers to accumulate in the tumor tissue but may result in side effects during higher dose of treatment. On the other hand, the strategies for actively targeting miRNA therepeutics to cancerous cells through nano-conjugates or vesicles by decorating their surface with antibodies against or ligands for HCC-specific antigens or receptors are more efficient in preventing damage to healthy tissue and cancer recurrence.

Structural Insights into the Host-Guest Complexation between β-Cyclodextrin and Bio-Conjugatable Adamantane Derivatives

Understanding the host–guest chemistry of α-/β-/γ- cyclodextrins (CDs) and a wide range of organic species are fundamentally attractive, and are finding broad contemporary applications toward developing efficient drug delivery systems. With the widely used β-CD as the host, we herein demonstrate that its inclusion behaviors toward an array of six simple and bio-conjugatable adamantane derivatives, namely, 1-adamantanol (adm-1-OH), 2-adamantanol (adm-2-OH), adamantan-1-amine (adm-1-NH₂), 1-adamantanecarboxylic acid (adm-1-COOH), 1,3-adamantanedicarboxylic acid (adm-1,3-diCOOH), and 2-[3-(carboxymethyl)-1-adamantyl]acetic acid (adm-1,3-diCH₂COOH), offer inclusion adducts with diverse adamantane-to-CD ratios and spatial guest locations. In all six cases, β-CD crystallizes as a pair supported by face-to-face hydrogen bonding between hydroxyl groups on C2 and C3 and their adjacent equivalents, giving rise to a truncated-cone-shaped cavity to accommodate one, two, or three adamantane derivatives. These inclusion complexes can be terminated as (adm-1-OH)₂⊂CD₂ (1, 2:2), (adm-2-OH)₃⊂CD₂ (2, 3:2), (adm-1-NH₂)₃⊂CD₂ (3, 3:2), (adm-1-COOH)₂⊂CD₂ (4, 2:2), (adm-1,3-diCOOH)⊂CD₂ (5, 1:2), and (adm-1,3-diCH₂COOH)⊂CD₂ (6, 1:2). This work may shed light on the design of nanomedicine with hierarchical structures, mediated by delicate cyclodextrin-based hosts and adamantane-appended drugs as the guests.

Recent Advances in miRNA Delivery Systems

MicroRNAs (miRNAs) represent a family of short non-coding regulatory RNA molecules that are produced in a tissue and time-specific manner to orchestrate gene expression post-transcription. MiRNAs hybridize to target mRNA(s) to induce translation repression or mRNA degradation. Functional studies have demonstrated that miRNAs are engaged in virtually every physiological process and, consequently, miRNA dysregulations have been linked to multiple human pathologies. Thus, miRNA mimics and anti-miRNAs that restore miRNA expression or downregulate aberrantly expressed miRNAs, respectively, are highly sought-after therapeutic strategies for effective manipulation of miRNA levels. In this regard, carrier vehicles that facilitate proficient and safe delivery of miRNA-based therapeutics are fundamental to the clinical success of these pharmaceuticals. Here, we highlight the strengths and weaknesses of current state-of-the-art viral and non-viral miRNA delivery systems and provide perspective on how these tools can be exploited to improve the outcomes of miRNA-based therapeutics.

In vivo gene delivery mediated by non-viral vectors for cancer therapy

Gene therapy by expression constructs or down-regulation of certain genes has shown great potential for the treatment of various diseases. The wide clinical application of nucleic acid materials dependents on the development of biocompatible gene carriers. There are enormous various compounds widely investigated to be used as non-viral gene carriers including lipids, polymers, carbon materials, and inorganic structures. In this review, we will discuss the recent discoveries on non-viral gene delivery systems. We will also highlight the in vivo gene delivery mediated by non-viral vectors to treat cancer in different tissue and organs including brain, breast, lung, liver, stomach, and prostate. Finally, we will delineate the state-of-the-art and promising perspective of in vivo gene editing using non-viral nano-vectors.

A novel targeted delivery system for drug-resistant hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is a severe malignant disease threatening human life. Current chemotherapy methods usually result in poor prognosis with low treatment efficacy and high side effects because of weak targeting specificity and fast acquisition of multidrug resistance (MDR). HCSP4 is a 12-aa peptide previously identified to specifically and sensitively bind to HCC cells and tissues. In this study, a novel class of HCC-targeting doxorubicin (DOX) delivery system, named HCSP4-Lipo-DOX-miR101, was synthesized and investigated for anticancer activity. HCSP4-Lipo-DOX-miR101 exhibited specific HCC targeting characteristics and satisfactory anticancer potency against HepG2 and HepG2/ADR cells, particularly HepG2/ADR cells. Moreover, the expression levels of genes closely related to membrane transport and cancer growth were significantly suppressed. This finding suggests that HCSP4-Lipo-DOX-miR101 can cause DOX-resistant HCC cell death and growth inhibition based on the targeting of MDR-related genes by miR-101. In conclusion, the findings of this study suggest that HCSP4-Lipo-DOX-miR101 may serve as a promising novel targeted delivery system for improving the therapeutic efficiency of drug-resistant hepatocellular carcinoma.

A Comprehensive Review of Cancer MicroRNA Therapeutic Delivery Strategies

In the field of molecular oncology, microRNAs (miRNAs) and their role in regulating physiological processes and cancer pathogenesis have been a revolutionary discovery over the last decade. It is now considered that miRNA dysregulation influences critical molecular pathways involved in tumor progression, invasion, angiogenesis and metastasis in a wide range of cancer types. Hence, altering miRNA levels in cancer cells has promising potential as a therapeutic intervention, which is discussed in many other articles in this Special Issue. Some of the most significant hurdles in therapeutic miRNA usage are the stability and the delivery system. In this review, we cover a comprehensive update on the challenges and strategies for the development of therapeutic miRNA delivery systems that includes virus-based delivery, non-viral delivery (artificial lipid-based vesicles, polymer-based or chemical structures), and recently emerged extracellular vesicle (EV)-based delivery systems.

Tumor-triggered personalized microRNA cocktail therapy for hepatocellular carcinoma

miRNA cocktail therapy based on pH-responsive nanoparticles featuring PEG detachment and size transformation is a potential strategy for HCC treatment.

Macrocyclic Compounds for Drug and Gene Delivery in Immune-Modulating Therapy

For decades, macrocyclic compounds have been widely applied in various fields owing to essential physicochemical properties such as their rigid cyclic structures, geometric dimensions (diameter and height), hydrophobic cavity, and hydrophilic interface. This review is an attempt to summarize various research accomplishments involving macrocyclic compounds for drug and gene delivery in immune-modulating therapies: the structures and benefits of main host molecules, their mechanisms regulating the immune system from cell uptake to activation of dendritic cells and T helper lymphocytes, as well as their potential immunotherapy for different diseases. Macrocyclic compounds including cucurbiturils (CBs), calixarenes, pillararenes, cyclodextrins (CyDs), macrocyclic peptides and metallo-supramolecular compounds, have their own unique physicochemical properties and functional derivatizations that enable to improve the biocompatibility, responsiveness to stimuli, and effectiveness of immune-modulating therapy. Based on abundant clarifications of the biological immunity mechanisms, representative constructions of macrocyclic compounds for immune therapies have been conducted for the investigation of treatment of different diseases including cancer, atherosclerosis, Niemann-Pick type C1 disease (NPC1), diabetes, and inflammations. Although there are critical challenges that remain to be conquered, we believe the future of macrocyclic compounds in the immune-modulating therapy must be bright.

Engineering Nanoparticles for Targeted Delivery of Nucleic Acid Therapeutics in Tumor

In the past 10 years, with the increase of investment in clinical nano-gene therapy, there are many trials that have been discontinued due to poor efficacy and serious side effects. Therefore, it is particularly important to design a suitable gene delivery system. In this paper, we introduce the application of liposomes, polymers, and inorganics in gene delivery; also, different modifications with some stimuli-responsive systems can effectively improve the efficiency of gene delivery and reduce cytotoxicity and other side effects. Besides, the co-delivery of chemotherapy drugs with a drug tolerance-related gene or oncogene provides a better theoretical basis for clinical cancer gene therapy.

Roles of MicroRNA-34a in Epithelial to Mesenchymal Transition, Competing Endogenous RNA Sponging and Its Therapeutic Potential

MicroRNA-34a (miR-34a), a tumor suppressor, has been reported to be dysregulated in various human cancers. MiR-34a is involves in certain epithelial-mesenchymal transition (EMT)-associated signal pathways to repress tumorigenesis, cancer progression, and metastasis. Due to the particularity of miR-34 family in tumor-associated EMT, the significance of miR-34a is being increasingly recognized. Competing endogenous RNA (ceRNA) is a novel concept involving mRNA, circular RNA, pseudogene transcript, and long noncoding RNA regulating each other’s expressions using microRNA response elements to compete for the binding of microRNAs. Studies showed that miR-34a is efficient for cancer therapy. Here, we provide an overview of the function of miR-34a in tumor-associated EMT. ceRNA hypothesis plays an important role in miR-34a regulation in EMT, cancer progression, and metastasis. Its potential roles and challenges as a microRNA therapeutic candidate are discussed. As the negative effect on cancer progression, miR-34a should play crucial roles in clinical diagnosis and cancer therapy.

MicroRNA-34 family: a potential tumor suppressor and therapeutic candidate in cancer

MicroRNA-34 (miR-34) has been reported to be dysregulated in various human cancers and regarded as a tumor suppressive microRNA because of its synergistic effect with the well-known tumor suppressor p53. Along with the application of MRX34, the first tumor-targeted microRNA drug which based on miR-34a mimics, on phase I clinical trial (NCT01829971), the significance of miR-34 is increasingly recognized. miR-34 plays a crucial role on repressing tumor progression by involving in epithelial-mesenchymal transition (EMT) via EMT- transcription factors, p53 and some important signal pathways. Not only that, numerous preclinical researches revealed the giant potential of miR-34a on cancer therapy through diversiform nano-scaled delivery systems. Here, we provide an overview about the function of miR-34 in various cancers and the mechanism of miR-34 in tumor-associated EMT. Furthermore, its potential role as a microRNA therapeutic candidate is also discussed. Notwithstanding some obstacles existed, the extensive application prospect of miR-34 on oncotherapy cannot be neglected.

A PEGylated megamer-based microRNA delivery system activatable by stepwise microenvironment stimulation

A biodegradable, oncosensitive, megamer-based delivery system has been developed for microenvironment-activatable miRNA therapy.

Sialic-Acid-Anchored Micelles: A Hierarchical Targeting Device for Enhanced Tumor Tissue Accumulation and Cellular Internalization

Targeted drug delivery systems (TDDS) have attracted wide attention for their reduced drug side effects and improved antitumor efficacy in comparison with traditional preparations. While targeting moieties in existing TDDS have principally focused on recognition of receptors on the surface of tumor cells, accumulation into tumor tissue only could be performed by enhanced permeability and retention effects and active transportation into tumor cells. Doxorubicin (DOX)-loaded sialic acid-dextran (Dex)-octadecanoic acid (OA) micelles (SA-Dex-OA/DOX) were designed for targeting hepatocellular carcinoma effectively. The synthesized conjugates could self-aggregate to form micelles with a critical micelle concentration of 27.6 μg·mL^-1 and diameter of 54.53 ± 3.23 nm. SA-Dex-OA micelles incorporated with 4.36% DOX-loading content could prolong in vitro drug release to 96 h with 80% of final release. Cellular transportation studies revealed that SA-Dex-OA micelles mediated more efficient DOX delivery into Bel-7402 cells than those without SA modification. In vivo biodistribution testing demonstrated that SA-Dex-OA/ICG micelles showed 3.05-fold higher accumulation into Bel-7402 tumors. The recognition of overexpressed E-selectin in inflammatory tumor vascular endothelial cells led to a large accumulation of SA-Dex-OA/ICG micelles into tumor tissue, and the E-selectin upregulated on the surface of tumor cells contributed to active cellular transportation into tumor cells. Accordingly, SA-Dex-OA/DOX exhibited prior suppression of Bel-7402 tumor growth greater than that of Dex-OA/DOX micelles and free DOX (the tumor inhibition: 79.2% vs 61.0 and 51.3%). These results suggest that SA-functionalized micelles with dual targeting properties have high potential for liver cancer therapy.

Reduction-sensitive polymeric nanomedicines: An emerging multifunctional platform for targeted cancer therapy

The development of smart delivery systems that are robust in circulation and quickly release drugs following selective internalization into target cancer cells is a key to precision cancer therapy. Interestingly, reduction-sensitive polymeric nanomedicines showing high plasma stability and triggered cytoplasmic drug release behavior have recently emerged as one of the most exciting platforms for targeted delivery of various anticancer drugs including small chemical drugs, proteins, and nucleic acids. In vivo studies in varying tumor models reveal that these reduction-sensitive multifunctional nanomedicines outperform the currently used clinical formulations and reduction-insensitive counterparts, bringing about not only significantly enhanced tumor selectivity, accumulation and inhibition efficacy but also markedly reduced systemic toxicity and improved therapeutic index. In this review, we will highlight the cutting-edge advancement with a focus on in vivo performances as well as future perspectives on reduction-sensitive polymeric nanomedicines for targeted cancer therapy.

A novel controlled release formulation of the Pin1 inhibitor ATRA to improve liver cancer therapy by simultaneously blocking multiple cancer pathways

Hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths worldwide largely due to lack of effective targeted drugs to simultaneously block multiple cancer-driving pathways. The identification of all-trans retinoic acid (ATRA) as a potent Pin1 inhibitor provides a promising candidate for HCC targeted therapy because Pin1 is overexpressed in most HCC and activates numerous cancer-driving pathways. However, the efficacy of ATRA against solid tumors is limited due to its short half-life of 45min in humans. A slow-releasing ATRA formulation inhibits solid tumors such as HCC, but can be used only in animals. Here, we developed a one-step, cost-effective route to produce a novel biocompatible, biodegradable, and non-toxic controlled release formulation of ATRA for effective HCC therapy. We used supercritical carbon dioxide process to encapsulate ATRA in largely uniform poly L-lactic acid (PLLA) microparticles, with the efficiency of 91.4% and yield of 68.3%, and ~4-fold higher Cmax and AUC over the slow-releasing ATRA formulation. ATRA-PLLA microparticles had good biocompatibility, and significantly enhanced the inhibitory potency of ATRA on HCC cell growth, improving IC50 by over 3-fold. ATRA-PLLA microparticles exerted its efficacy likely through degrading Pin1 and inhibiting multiple Pin1-regulated cancer pathways and cell cycle progression. Indeed, Pin1 knock-down abolished ATRA inhibitory effects on HCC cells and ATRA-PLLA did not inhibit normal liver cells, as expected because ATRA selectively inhibits active Pin1 in cancer cells. Moreover ATRA-PLLA microparticles significantly enhanced the efficacy of ATRA against HCC tumor growth in mice through reducing Pin1, with a better potency than the slow-releasing ATRA formulation, consistent with its improved pharmacokinetic profiles. This study illustrates an effective platform to produce controlled release formulation of anti-cancer drugs, and ATRA-PLLA microparticles might be a promising targeted drug for HCC therapy as PLLA is biocompatible, biodegradable and nontoxic to humans.

EGFR-targeted multifunctional polymersomal doxorubicin induces selective and potent suppression of orthotopic human liver cancer in vivo

Liver cancer is a globally leading malignancy that has a poor five-year survival rate of less than 20%. The systemic chemotherapeutics are generally ineffective for liver cancers partly due to fast clearance and low tumor uptake. Here, we report that GE11 peptide functionalized polymersomal doxorubicin (GE11-PS-DOX) effectively targets and inhibits epidermal growth factor receptor (EGFR)-positive SMMC7721 orthotopic human liver tumor xenografts in mice. GE11-PS-DOX with a GE11 surface density of 10% displayed a high drug loading of 15.4 wt%, a small size of 78 nm, and glutathione-triggered release of DOX. MTT assays, flow cytometry and confocal microscopy studies revealed that GE11-PS-DOX mediated obviously more efficient DOX delivery into SMMC7721 cells than the non-targeting PS-DOX and clinically used liposomal doxorubicin (Lipo-DOX) controls. The in vivo studies showed that GE11-PS-DOX had a long circulation time and an extraordinary accumulation in the tumors (13.3 %ID/g). Interestingly, GE11-PS-DOX caused much better treatment of SMMC7721 orthotopic liver tumor-bearing mice as compared to PS-DOX and Lipo-DOX. The mice treated with GE11-PS-DOX (12 mg DOX equiv./kg) exhibited a significantly improved survival rate (median survival time: 130 days versus 70 and 38 days for PS-DOX at 12 mg DOX equiv./kg and Lipo-DOX at 6 mg DOX equiv./kg, respectively) and achieved 50% complete regression. Notably, GE11-PS-DOX induced obviously lower systemic toxicity than Lipo-DOX. EGFR-targeted multifunctional polymersomal doxorubicin with improved efficacy and safety has a high potential for treating human liver cancers.

STATEMENT OF SIGNIFICANCE

Liver cancer is one of the top five leading causes of cancer death worldwide. The systemic chemotherapeutics and biotherapeutics generally have a low treatment efficacy for hepatocellular carcinoma partly due to fast clearance and/or low tumor uptake. Nanomedicines based on biodegradable micelle and polymersomes offer a most promising treatment for malignant liver cancers. Their clinical effectiveness remains, however, suboptimal owing to issues like inadequate systemic stability, low tumor accumulation and selectivity, and poor control over drug release. Here we report that GE11 peptide-functionalized, disulfide-crosslinked multifunctional polymersomal doxorubicin (GE11-PS-DOX) can effectively suppress the growth of orthotopic SMMC7721 human liver tumors in nude mice. They showed significantly decreased systemic toxicity and improved mouse survival rate with 3.4-fold longer median survival time as compared to clinically used pegylated liposomal doxorubicin (Lipo-DOX) and achieving 50% complete regression. GE11-PS-DOX, based on PEG-PTMC is biodegradable, nontoxic, and easy to prepare, appears as a safe, robust, versatile and all-function-in-one nanoplatform that has a high potential in targeted chemotherapy of EGFR expressed hepatocellular carcinoma.

An ATP-Responsive Codelivery System of Doxorubicin and MiR-34a To Synergistically Inhibit Cell Proliferation and Migration

Establishing stimulus-responsive nanosystems for the codelivery of anticancer drug and oligonucleotide is a promising strategy in cancer treatment owing to the combination of chemotherapy and gene therapy in a synergistic manner. Herein, an ATP aptamer and its cDNA sequence were first hybridized to produce the duplex, into which chemotherapeutic agent doxorubicin (DOX) interacted through the GC-rich motif of duplex, and PEI25K was then employed as a carrier to condense the DOX-loading duplex and miR-34a to construct the ternary nanocomplex PEI/DOX-Duplex/miR-34a. The nanocomplex exhibited a favorable drug release profile through the response to high concentration of ATP in the cytosol. The ATP-responsive delivery system was demonstrated to possess higher antiproliferative effect (cell viability of <40%) than the single cargo delivery, which could be attributed to the synergistic induction of cell apoptosis and cell cycle arrest from DOX and miR-34a. Furthermore, wound healing and Transwell assay elucidated the higher antimigration effect of ternary nanocomplex than DOX-Duplex or miR-34a delivery. Overall, the combinatorial delivery of DOX and miR-34a through an ATP-responsive manner could trigger the rapid release of cargoes in the cytosol and enhance the inhibition of cell proliferation and migration through the synergistic manner of these two components.

Inhibition of Kupffer Cell Autophagy Abrogates Nanoparticle-Induced Liver Injury

The possible adverse effects of engineered nanomaterials on human health raise increasing concern as our research on nanosafety intensifies. Upon entry into a human body, whether intended for a theranostic purpose or through unintended exposure, nanomaterials tend to accumulate in the liver, leading to hepatic damage. A variety of nanoparticles, including rare earth upconversion nanoparticles (UCNs), have been reported to elicit hepatotoxicity, in most cases through inducing immune response or activating reactive oxygen species. Many of these nanoparticles also induce autophagy, and autophagy inhibition has been shown to decrease UCN-induced liver damage. Herein, using UCNs as a model engineered nanomaterial, this study uncovers a critical role for Kupffer cells in nanomaterial-induced liver toxicity, as depletion of Kupffer cells significantly exacerbates UCN-induced liver injury. Furthermore, UCN-induced prodeath autophagy in Kupffer cells, and inhibition of autophagy with 3-MA, a well-established chemical inhibitor of autophagy, enhances Kupffer cell survival and further abrogates UCN-induced liver toxicity. The results reveal the critical importance of Kupffer cell autophagy for nanoparticle-induced liver damage, and inhibition of autophagy may constitute a novel strategy for abrogating nanomaterial-elicited liver toxicity.