Assessment of drug delivery and anticancer potentials of nanoparticles-loaded siRNA targeting STAT3 in lung cancer, in vitro and in vivo

Transitional Insight into the RNA-Based Oligonucleotides in Cancer Treatment

Conventional cancer therapies with chemodrugs suffer from various disadvantages, such as irreversible side effects on the skin, heart, liver, and nerves with even fatal consequences. RNA-based therapeutic is a novel technology which offers great potential as non-toxic, non-infectious, and well-tolerable platform. Herein, we introduce different RNA-based platforms with a special focus on siRNA, miRNA, and mRNA applications in cancer treatment in order to better understand the details of their therapeutic effects. Of note, the co-delivery of RNAs with other distinct RNA or drugs has provided safe, efficient, and novel treatment modalities for cancer treatment.

Excipients for Novel Inhaled Dosage Forms: An Overview

Pulmonary drug delivery is a form of local targeting to the lungs in patients with respiratory disorders like cystic fibrosis, pulmonary arterial hypertension (PAH), asthma, chronic pulmonary infections, and lung cancer. In addition, noninvasive pulmonary delivery also presents an attractive alternative to systemically administered therapeutics, not only for localized respiratory disorders but also for systemic absorption. Pulmonary delivery offers the advantages of a relatively low dose, low incidence of systemic side effects, and rapid onset of action for some drugs compared to other systemic administration routes. While promising, inhaled delivery of therapeutics is often complex owing to factors encompassing mechanical barriers, chemical barriers, selection of inhalation device, and limited choice of dosage form excipients. There are very few excipients that are approved by the FDA for use in developing inhaled drug products. Depending upon the dosage form, and inhalation devices such as pMDIs, DPIs, and nebulizers, different excipients can be used to provide physical and chemical stability and to deliver the dose efficiently to the lungs. This review article focuses on discussing a variety of excipients that have been used in novel inhaled dosage forms as well as inhalation devices.

Clickable polyethyleneimine incorporated into triblock copolymeric micelles as an efficient platform in the delivery of siRNA to NSCLC cells

The efficacy of transfection vectors to cross the endosomal membrane into the cytosol is a central aspect in the development of nucleic acid-based therapeutics. The challenge remains the same: Delivery, Delivery, Delivery. Despite a rational and appropriate construct of triblock polymeric micelles, which could serve as an ideal platform for the co-delivery of siRNAs and hydrophobic anticancer drugs, we show here its inability to properly convey oligonucleotides to their final destination. In order to overcome biological barriers, a linear PEI comprising two orthogonal groups was synthesized, holding an appropriate balance between safety and efficacy. Micellar carriers were then formulated with this polymer to enhance endosomal siRNA release. This chemical technology also addresses the two major challenges to consider when developing novel micellar products for siRNA delivery, namely cytotoxicity of polycations and endosomal escape. Herein, we demonstrate successful release of siRNA using a polymer tailoring strategy combined with a relevant in vitro approach, considering STAT3 as a promising target in the treatment of non-small cell lung cancer (NSCLC).

Oligonucleotide-Based Therapeutics for STAT3 Targeting in Cancer-Drug Carriers Matter

High expression and phosphorylation of signal transducer and transcription activator 3 (STAT3) are correlated with progression and poor prognosis in various types of cancer. The constitutive activation of STAT3 in cancer affects processes such as cell proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. The importance of STAT3 in cancer makes it a potential therapeutic target. Various methods of directly and indirectly blocking STAT3 activity at different steps of the STAT3 pathway have been investigated. However, the outcome has been limited, mainly by the number of upstream proteins that can reactivate STAT3 or the relatively low specificity of the inhibitors. A new branch of molecules with significant therapeutic potential has emerged thanks to recent developments in the regulatory function of non-coding nucleic acids. Oligonucleotide-based therapeutics can silence target transcripts or edit genes, leading to the modification of gene expression profiles, causing cell death or restoring cell function. Moreover, they can reach untreatable targets, such as transcription factors. This review briefly describes oligonucleotide-based therapeutics that found application to target STAT3 activity in cancer. Additionally, this review comprehensively summarizes how the inhibition of STAT3 activity by nucleic acid-based therapeutics such as siRNA, shRNA, ASO, and ODN-decoy affected the therapy of different types of cancer in preclinical and clinical studies. Moreover, due to some limitations of oligonucleotide-based therapeutics, the importance of carriers that can deliver nucleic acid molecules to affect the STAT3 in cancer cells and cells of the tumor microenvironment (TME) was pointed out. Combining a high specificity of oligonucleotide-based therapeutics toward their targets and functionalized nanoparticles toward cell type can generate very efficient formulations.

Nanomedicine as potential cancer therapy via targeting dysregulated transcription factors

Cancer as a disease possess quite complicated pathophysiological implications and is among the prominent causes of morbidity and mortality on global scales. Anti-cancer chemotherapy, surgery, and radiation therapy are some of the present-day conventional treatment options. However, these therapeutic paradigms own several retreats, including lack of specificity, non-targeted toxicological implications, inefficient drug delivery to targeted cells, and emergence of cancer resistance, ultimately causing ineffective cancer management. Owing to the advanced and better biophysical characteristic features and potentiality for the tailoring and customizations and in several fashions, nanotechnology can entirely transubstantiate the cancer identification and its managements. Additionally, nanotechnology also renders several answers to present-day mainstream limitations springing-up in anti-cancer therapeutics. Nanocarriers, owing to their outstanding physicochemical features including but not limited to their particle size, surface morphological features viz. shape etc., have been employed in nanomedicinal platforms for targeting various transcription factors leading to worthy pharmacological outcomes. This transcription targeting activates the wide array of cellular and molecular events like antioxidant enzyme-induction, apoptotic cell death, cell-cycle arrest etc. These outcomes are obtained after the activation or inactivation of several transcription factors and cellular pathways. Further, nanoformulations have been precisely calibrated and functionalized with peculiar targeting groups for improving their efficiency to deliver the drug-payload to specified and targeted cancerous cells and tissues. This review undertakes an extensive, across-the-board and all-inclusive approach consisting of various studies encompassing different types of tailored and customized nanoformulations and nanomaterials designed for targeting the transcription factors implicated in the process of carcinogenesis, tumor-maturation, growth and metastasis. Various transcription factors viz. nuclear factor kappa (NF-κB), signal transducer and activators of transcription (STAT), Cmyc and Twist-related protein 1 (TWIST1) along with several types of nanoparticles targeting these transcription factors have been summarized here. A section has also been dedicated to the different types of nanoparticles targeting the hypoxia inducing factors. Efforts have been made to summarize several other transcription factors implicated in various stages of cancer development, growth, progression and invasion, and their targeting with different kinds of nanomedicinal agents.

Emerging strategies in nanotechnology to treat respiratory tract infections: realizing current trends for future clinical perspectives

A boom in respiratory tract infection cases has inflicted a socio-economic burden on the healthcare system worldwide, especially in developing countries. Limited alternative therapeutic options have posed a major threat to human health. Nanotechnology has brought an immense breakthrough in the pharmaceutical industry in a jiffy. The vast applications of nanotechnology ranging from early diagnosis to treatment strategies are employed for respiratory tract infections. The research avenues explored a multitude of nanosystems for effective drug delivery to the target site and combating the issues laid through multidrug resistance and protective niches of the bacteria. In this review a brief introduction to respiratory diseases and multifaceted barriers imposed by bacterial infections are enlightened. The manuscript reviewed different nanosystems, i.e. liposomes, solid lipid nanoparticles, polymeric nanoparticles, dendrimers, nanogels, and metallic (gold and silver) which enhanced bactericidal effects, prevented biofilm formation, improved mucus penetration, and site-specific delivery. Moreover, most of the nanotechnology-based recent research is in a preclinical and clinical experimental stage and safety assessment is still challenging.

Polyester nanomedicines targeting inflammatory signaling pathways for cancer therapy

The growth of cancerous cells and their responses towards substantial therapeutics are primarily controlled by inflammations (acute and chronic) and inflammation-associated products, which either endorse or repress tumor progression. Additionally, major signaling pathways, including NF-κB, STAT3, inflammation-causing factors (cytokines, TNF-α, chemokines), and growth-regulating factors (VEGF, TGF-β), are vital regulators responsible for the instigation and resolution of inflammations. Moreover, the conventional chemotherapeutics have exhibited diverse limitations, including poor pharmacokinetics, unfavorable chemical properties, poor targetability to the disease-specific disease leading to toxicity; thus, their applications are restricted in inflammation-mediated cancer therapy. Furthermore, nanotechnology has demonstrated potential benefits over conventional chemotherapeutics, such as it protected the incorporated drug/bioactive moiety from enzymatic degradation within the systemic circulation, improving the physicochemical properties of poorly aqueous soluble chemotherapeutic agents, and enhancing their targetability in specified carcinogenic cells rather than accumulating in the healthy cells, leading reduced cytotoxicity. Among diverse nanomaterials, polyester-based nanoparticulate delivery systems have been extensively used to target various inflammation-mediated cancers. This review summarizes the therapeutic potentials of various polyester nanomaterials (PLGA, PCL, PLA, PHA, and others)-based delivery systems targeting multiple signaling pathways related to inflammation-mediated cancer.

Role of STAT3 in the initiation, progression, proliferation and metastasis of breast cancer and strategies to deliver JAK and STAT3 inhibitors

INTRODUCTION

Breast cancer (BC) accounts for the majority of cancers among the female population. Anomalous activation of various signaling pathways has become an issue of concern. The JAK-STAT signaling pathway is activated in numerous cancers, including BC. STAT3 is widely involved in BCs, as 40 % of BCs display phosphorylated STAT3. JAK-STAT signaling is crucial for proliferation, survival, metastasis and other cellular events associated with the tumor microenvironment. Hence, targeting this pathway has become an area of interest among researchers.

KEY FINDINGS

This review article focuses on the role of STAT3 in the initiation, proliferation, progression and metastasis of BC. The roles of various phytochemicals, synthetic molecules and biologicals against JAK-STAT and STAT3 in various cancers have been discussed, with special emphasis on BC.

SIGNIFICANCE

JAK and STAT3 are involved in various phases from initiation to metastasis, and targeting this pathway is a promising approach to inhibit the various stages of BC development and to prevent metastasis. A number of phytochemicals and synthetic and biological molecules have demonstrated potential inhibitory effects on JAK and STAT3, thereby paving the way for the development of better therapeutics against BC.

Inhaled antibiotic-loaded polymeric nanoparticles for the management of lower respiratory tract infections

Lower respiratory tract infections (LRTIs) are one of the leading causes of deaths in the world. Currently available treatment for this disease is with high doses of antibiotics which need to be administered frequently. Instead, pulmonary delivery of drugs has been considered as one of the most efficient routes of drug delivery to the targeted areas as it provides rapid onset of action, direct deposition of drugs into the lungs, and better therapeutic effects at low doses and is self-administrable by the patients. Thus, there is a need for scientists to design more convenient pulmonary drug delivery systems towards the innovation of a novel treatment system for LRTIs. Drug-encapsulating polymer nanoparticles have been investigated for lung delivery which could significantly reduce the limitations of the currently available treatment system for LRTIs. However, the selection of an appropriate polymer carrier for the drugs is a critical issue for the successful formulations of inhalable nanoparticles. In this review, the current understanding of LRTIs, management systems for this disease and their limitations, pulmonary drug delivery systems and the challenges of drug delivery through the pulmonary route are discussed. Drug-encapsulating polymer nanoparticles for lung delivery, antibiotics used in pulmonary delivery and drug encapsulation techniques have also been reviewed. A strong emphasis is placed on the impact of drug delivery into the infected lungs.

Recent advances in co-delivery nanosystems for synergistic action in cancer treatment

Nanocarrier delivery systems have been widely studied to carry unique or dual chemical drugs. The major challenge of chemotherapies is to overcome the multidrug-resistance (MDR) of cells to antineoplastic medicines. In this context, nano-scale technology has allowed researchers to develop biocompatible nano-delivery systems to overcome the limitation of chemical agents. The development of nano-vehicles may also be directed to co-deliver different agents such as drugs and genetic materials. The delivery of nucleic acids targeting specific cells is based on gene therapy principles to replace the defective gene, correct genome errors or knock-down a particular gene. Co-delivery systems are attractive strategies due to the possibility of achieving synergistic therapeutic effects, which are more effective in overcoming the MDR of cancer cells. These combined therapies can provide better outcomes than separate delivery approaches carrying either siRNA, miRNA, pDNA, or drugs. This article reviews the main design features that need to be associated with nano-vehicles to co-deliver drugs, genes, and gene-drug combinations with efficacy. The advantages and disadvantages of co-administration approaches are also overviewed and compared with individual nanocarrier systems. Herein, future trends and perspectives in designing novel nano-scale platforms to co-deliver therapeutic agents are also discussed.

Lung carcinoma spheroids embedded in a microfluidic platform

Three-dimensional (3D) spheroid cell cultures are excellent models used in cancer biology research and drug screening. The objective of this study was to develop a lung carcinoma spheroid based microfluidic platform with perfusion function to mimic lung cancer pathology and investigate the effect of a potential drug molecule, panaxatriol. Spheroids were successfully formed on agar microtissue molds at the end of 10 days, reaching an average diameter of about 317.18 ± 4.05 μm and subsequently transferred to 3D dynamic microfluidic system with perfusion function. While the size of the 3D spheroids embedded in the Matrigel matrix in the platform had gradually increased both in the static and dynamic control groups, the size of the spheroids were reduced and fragmented in the drug treated groups. Cell viability results showed that panaxatriol exhibited higher cytotoxic effect on cancer cells than healthy cells and the IC₅₀ value was determined as 61.55 µM. Furthermore, panaxatriol has been more effective on single cells around the spheroid structure, whereas less in 3D spheroid tissues with a compact structure in static conditions compared to dynamic systems, where a flow rate of 2 µL/min leading to a shear stress of 0.002 dyne/cm² was applied. Application of such dynamic systems will contribute to advancing basic research and increasing the predictive accuracy of potential drug molecules, which may accelerate the translation of novel therapeutics to the clinic, possibly decreasing the use of animal models.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-021-00470-7.

Nanotechnology to the Rescue: Treatment Perspective for the Immune Dysregulation Observed in COVID-19

The study of the use of nanotechnology for drug delivery has been extensive. Nanomedical approaches for therapeutics; drug delivery in particular is superior to conventional methods in that it allows for controlled targeted delivery and release, higher stability, extended circulation time, minimal side-effects, and improved pharmacokinetic clearance (of the drug) form the body, to name a few. The magnitude of COVID-19, the current ongoing pandemic has been severe; it has caused widespread the loss of human life. In individuals with severe COVID-19, immune dysregulation and a rampant state of hyperinflammation is observed. This kind of an immunopathological response is detrimental and results in rapid disease progression, development of secondary infections, sepsis and can be fatal. Several studies have pin-pointed the reason for this immune dysregulation; deviations in the signaling pathways involved in the mediation and control of immune responses. In severe COVID-19 patients, many signaling cascades including JAK/STAT, NF-κB, MAPK/ERK, TGF beta, VEGF, and Notch signaling were found to be either upregulated or inactivated. Targeting these aberrant signaling pathways in conjunction with antiviral therapy will effectuate mitigation of the hyperinflammation, hypercytokinemia, and promote faster recovery. The science of the use of nanocarriers as delivery agents to modulate these signaling pathways is not new; it has already been explored for other inflammatory diseases and in particular, cancer therapy. Numerous studies have evaluated the efficacy and potential of nanomedical approaches to modulate these signaling pathways and have been met with positive results. A treatment regime, that includes nanotherapeutics and antiviral therapies will prove effective and holds great promise for the successful treatment of COVID-19. In this article, we review different nanomedical approaches already studied for targeting aberrant signaling pathways, the host immune response to SARS-CoV-2, immunopathology and the dysregulated signaling pathways observed in severe COVID-19 and the current treatment methods in use for targeting signaling cascades in COVID-19. We then conclude by suggesting that the use of nanomedical drug delivery systems for targeting signaling pathways can be extended to effectively target the aberrant signaling pathways in COVID-19 for best treatment results.

Recent Progresses in Organic-Inorganic Nano Technological Platforms for Cancer Therapeutics

Nanotechnology offers promising tools in interdisciplinary research areas and getting an upsurge of interest in cancer therapeutics. Organic nanomaterials and inorganic nanomaterials bring revolutionary advancement in cancer eradication process. Oncology is achieving new heights under nano technological platform by expediting chemotherapy, radiotherapy, photo thermodynamic therapy, bio imaging and gene therapy. Various nanovectors have been developed for targeted therapy which acts as "Nano-bullets" for tumor cells selectively. Recently combinational therapies are catching more attention due to their enhanced effect leading towards the use of combined organicinorganic nano platforms. The current review covers organic, inorganic and their hybrid nanomaterials for various therapeutic action. The technological aspect of this review emphasizes on the use of inorganic-organic hybrids and combinational therapies for better results and also explores the future opportunities in this field.

Nanoparticulate RNA delivery systems in cancer

BACKGROUND

Drug delivery system is a common practice in cancer treatment. RNA interference-mediated post-transcriptional gene silencing holds promise as an approach to knockdown in the expression of target genes responsible for cancer cell growth and metastasis. RNA interference (RNAi) can be achieved by delivering small interfering RNA (siRNA) and short hairpin RNA (shRNA) to target cells. Since neither interfering RNAs can be delivered in naked form due to poor stability, an efficient delivery system is required that protects, guides, and delivers the siRNA and shRNA to target cells as part of cancer therapy (chemotherapy).

RECENT FINDINGS

In this review, a discussion is presented about the different types of drug delivery system used to deliver siRNA and shRNA, together with an overview of the potential benefits associated with this sophisticated biomolecular therapy. Improved understanding of the different approaches used in nanoparticle (NP) fabrication, along with an enhanced appreciation of the biochemical properties of siRNA/shRNA, will assist in developing improved drug delivery strategies in basic and clinical research.

CONCLUSION

These novel delivery techniques are able to solve the problems that form an inevitable part of delivering genes in more efficient manner and as part of more effective treatment protocols. The present review concludes that the nanoparticulate RNA delivery system has great possibility for cancer treatment along with several other proposed methods. Several NPs or nanocarriers are already in use, but the methods proposed here could fulfill the missing gap in cancer research. It is the future technology, which unravels the mystery of resolving genomic diseases that is, especially genomic instability and its signaling cascades.

Nanocarriers in effective pulmonary delivery of siRNA: current approaches and challenges

Research on siRNA is increasing due to its wide applicability as a therapeutic agent in irreversible medical conditions. siRNA inhibits expression of the specific gene after its delivery from formulation to cytosol region of a cell. RNAi (RNA interference) is a mechanism by which siRNA is silencing gene expression for a particular disease. Numerous studies revealed that naked siRNA delivery is not preferred due to instability and poor pharmacokinetic performance. Nanocarriers based delivery of siRNA has the advantage to overcome physiological barriers and protect the integrity of siRNA from degradation by RNAase. Various diseases like lung cancer, cystic fibrosis, asthma, etc can be treated effectively by local lung delivery. The selective targeted therapeutic action in diseased organ and least off targeted cytotoxicity are the key benefits of pulmonary delivery. The current review highlights recent developments in pulmonary delivery of siRNA with novel nanosized formulation approach with the proven in vitro/in vivo applications.

Multi-functional self-assembled nanoparticles for pVEGF-shRNA loading and anti-tumor targeted therapy

Although RNA interference (RNAi) technology shows great potential in cancer treatment, the tumor target delivery and sufficient cytosolic transport of RNAi agents are still the main obstacles for its clinical applications. Herein, we report a functional supramolecular self-assembled nanoparticle vector for RNAi agent loading and tumor target therapy. Molecular block adamantane-grafted poly(ethylene glycol) (Ad-PEG) was modified with epidermal growth factor receptor (EGFR)-specific binding ligand GE11 or pH-sensitive fusogenic peptide GALA and then used for self-assembly with cyclodextrin-grafted branched polyethylenimine (CD-PEI), adamantane-grafted polyamidoamine dendrimer (Ad-PAMAM), and plasmid DNA containing a small hairpin RNA expression cassette against vascular endothelial growth factor (VEGF) into functional DNA-loaded supramolecular nanoparticles (GE11&GALA-pshVEGF@SNPs) based on molecular recognition and charge interaction. These functional peptides facilitated the target cell binding, internalization, and endosomal escape of GE11&GALA-pshVEGF@SNPs, resulting in increased reporter gene expression and efficient targeted gene silencing. The systemic delivery of the GE11&GALA-pshVEGF@SNPs can efficiently downregulate the intratumoral VEGF protein levels, reduce blood vessel formation, and significantly inhibit A549 xenograft tumor growth. These results reveal the potential of these multifunctional self-assembled nanoparticles as a nucleic acid drug delivery system for the treatment of lung cancer.

Nanoparticles Targeting STATs in Cancer Therapy

Over the past decades, an increase in the incidence rate of cancer has been witnessed. Although many efforts have been made to manage and treat this life threatening condition, it is still one of the leading causes of death worldwide. Therefore, scientists have attempted to target molecular signaling pathways involved in cancer initiation and metastasis. It has been shown that signal transducers and activator of transcription (STAT) contributes to the progression of cancer cells. This important signaling pathway is associated with a number of biological processes including cell cycle, differentiation, proliferation and apoptosis. It appears that dysregulation of the STAT signaling pathway promotes the migration, viability and malignancy of various tumor cells. Hence, there have been many attempts to target the STAT signaling pathway. However, it seems that currently applied therapeutics may not be able to effectively modulate the STAT signaling pathway and suffer from a variety of drawbacks such as low bioavailability and lack of specific tumor targeting. In the present review, we demonstrate how nanocarriers can be successfully applied for encapsulation of STAT modulators in cancer therapy.

Delivering Combination Chemotherapies and Targeting Oncogenic Pathways via Polymeric Drug Delivery Systems

The side-effects associated with chemotherapy necessitates better delivery of chemotherapeutics to the tumor. Nanoparticles can load higher amounts of drug and improve delivery to tumors, increasing the efficacy of treatment. Polymeric nanoparticles, in particular, have been used extensively for chemotherapeutic delivery. This review describes the efforts made to deliver combination chemotherapies and inhibit oncogenic pathways using polymeric drug delivery systems. Combinations of chemotherapeutics with other drugs or small interfering RNA (siRNA) combinations have been summarized. Special attention is given to the delivery of drug combinations that involve either paclitaxel or doxorubicin, two popular chemotherapeutics in clinic. Attempts to inhibit specific pathways for oncotherapy have also been described. These include inhibition of oncogenic pathways (including those involving HER2, EGFR, MAPK, PI3K/Akt, STAT3, and HIF-1α), augmentation of apoptosis by inhibiting anti-apoptosis proteins (Bcl-2, Bcl-xL, and survivin), and targeting dysregulated pathways such as Wnt/β-catenin and Hedgehog.

Signal Transducer and Activator of Transcription (STATs) Proteins in Cancer and Inflammation: Functions and Therapeutic Implication

Signal Transducer and Activator of Transcription (STAT) pathway is connected upstream with Janus kinases (JAK) family protein and capable of integrating inputs from different signaling pathways. Each family member plays unique functions in signal transduction and crucial in mediating cellular responses to different kind of cytokines. STAT family members notably STAT3 and STAT5 have been involved in cancer progression whereas STAT1 plays opposite role by suppressing tumor growth. Persistent STAT3/5 activation is known to promote chronic inflammation, which increases susceptibility of healthy cells to carcinogenesis. Here, we review the role of STATs in cancers and inflammation while discussing current therapeutic implications in different cancers and test models, especially the delivery of STAT3/5 targeting siRNA using nanoparticulate delivery system.

VDAC1 is a molecular target in glioblastoma, with its depletion leading to reprogrammed metabolism and reversed oncogenic properties

Background

Glioblastoma (GBM), an aggressive brain tumor with frequent relapses and a high mortality, still awaits an effective treatment. Like many cancers, GBM cells acquire oncogenic properties, including metabolic reprogramming, vital for growth. As such, tumor metabolism is an emerging avenue for cancer therapy. One relevant target is the voltage-dependent anion channel 1 (VDAC1), a mitochondrial protein controlling cell energy and metabolic homeostasis.

Methods

We used VDAC1-specific short interfering (si)RNA (si-VDAC1) to treat GBM cell lines and subcutaneous or intracranial-orthotopic GBM xenograft mouse models. Tumors were monitored using MRI, immunohistochemistry, immunoblotting, immunofluorescence, quantitative real-time PCR, transcription factor expression, and DNA microarray analyses.

Results

Silencing VDAC1 expression using si-VDAC1 in 9 glioblastoma-related cell lines, including patient-derived cells, led to marked decreases in VDAC1 levels and cell growth. Using si-VDAC1 in subcutaneous or intracranial-orthotopic GBM models inhibited tumor growth and reversed oncogenic properties, such as reprogrammed metabolism, stemness, angiogenesis, epithelial-mesenchymal transition, and invasiveness. In cells in culture, si-VDAC1 inhibits cancer neurosphere formation and, in tumors, targeted cancer stem cells, leading to their differentiation into neuronal-like cells. These VDAC1 depletion-mediated effects involved alterations in transcription factors regulating signaling pathways associated with cancer hallmarks.

Conclusion

VDAC1 offers a target for GBM treatment, allowing for attacks on the interplay between metabolism and oncogenic signaling networks, leading to tumor cell differentiation into neuron- and astrocyte-like cells. Simultaneously attacking all of these processes, VDAC1 depletion overcame GBM heterogeneity and can replace several anticancer drugs that separately target angiogenesis, proliferation, or metabolism.

Targeting tumor microenvironment to curb chemoresistance via novel drug delivery strategies

INTRODUCTION

Tumor is a heterogeneous mass of malignant cells co-existing with non-malignant cells. This co-existence evolves from the initial developmental stages of the tumor and is one of the hallmarks of cancer providing a protumorigenic niche known as tumor microenvironment (TME). Proliferation, invasiveness, metastatic potential and maintenance of stemness through cross-talk between tumors and its stroma forms the basis of TME.

AREAS COVERED

The article highlights the developmental phases of a tumor from dysplasia to the formation of clinically detectable tumors. The authors discuss the mechanistic stages involved in the formation of TME and its contribution in tumor outgrowth and chemoresistance. The authors have reviewed various approaches for targeting TME and its hallmarks along with their advantages and pitfalls. The authors also highlight cancer stem cells (CSCs) that are resistant to chemotherapeutics and thus a primary reason for tumor recurrence thereby, posing a challenge for the oncologists.

EXPERT OPINION

Recent understanding of the cellular and molecular mechanisms involved in acquired chemoresistance has enabled scientists to target the tumor niche and TME and modulate and/or disrupt this communication leading to the transformation from a tumor-supportive niche environment to a tumor-non-supporting environment and give synergistic results towards an effective management of cancer.

Nanoparticle/siRNA-based therapy strategies in glioma: which nanoparticles, which siRNAs?

Nanomedicines allow for the delivery of small interfering RNAs (siRNAs) that are otherwise barely suitable as therapeutics for inducing RNA interference (RNAi). In preclinical studies on siRNA-based glioma treatment in vivo, various groups of nanoparticle systems, routes of administration and target genes have been explored. Targeted delivery by functionalization of nanoparticles with a ligand for crossing the blood-brain barrier and/or for enhanced target cell transfection has been described as well. Focusing on nanoparticle developments in the last approximately 10 years, this review article gives a comprehensive overview of nanoparticle systems for siRNA delivery into glioma and of preclinical in vivo studies. Furthermore, it discusses various target genes and highlights promising strategies with regard to target gene selection and combination therapies.

PLGA-loaded nanomedicines in melanoma treatment: Future prospect for efficient drug delivery

Current treatment methods for melanoma have some limitations such as less target-specific action, severe side effects and resistance to drugs. Significant progress has been made in exploring novel drug delivery systems based on suitable biochemical mechanisms using nanoparticles ranging from 10 to 400 nm for drug delivery and imaging, utilizing their enhanced penetration and retention properties. Poly-lactide-co-glycolide (PLGA), a copolymer of poly-lactic acid and poly-glycolic acid, provides an ideally suited performance-based design for better penetration into skin cells, thereby having a greater potential for the treatment of melanoma. Moreover, encapsulation protects the drug from deactivation by biological reactions and interactions with biomolecules, ensuring successful delivery and bioavailability for effective treatment. Controlled and sustained delivery of drugs across the skin barrier that otherwise prohibits entry of larger molecules can be successfully made with adequately stable biocompatible nanocarriers such as PLGA for taking drugs through the small cutaneous pores permitting targeted deposition and prolonged drug action. PLGA is now being extensively used in photodynamic therapy and targeted therapy through modulation of signal proteins and drug-DNA interactions. Recent advances made on these nanomedicines and their advantages in the treatment of skin melanoma are highlighted and discussed in this review.

Long and short noncoding RNAs in lung cancer precision medicine: Opportunities and challenges

The long and short noncoding RNAs have been involved in the molecular diagnosis, targeted therapy, and predicting prognosis of lung cancer. Utilizing noncoding RNAs as biomarkers and systemic RNA interference as an innovative therapeutic strategy has an immense likelihood to generate novel concepts in precision oncology. Targeting of RNA interference payloads such as small interfering RNAs, microRNA mimetic, or anti-microRNA (antagomirs) into specific cell types has achieved initial success. The clinical trials of noncoding RNA-based therapies are on the way with some positive results. Many attempts are done for developing novel noncoding RNA delivery strategies that could overcome systemic or local barriers. Furthermore, it precipitates concerted efforts to define the molecular subtypes of lung cancer, characterize the genomic landscape of lung cancer subtypes, identify novel therapeutic targets, and reveal mechanisms of sensitivity and resistance to targeted therapies. These efforts contribute a visible effect now in lung cancer precision medicine: patients receive molecular testing to determine whether their tumor harbors an actionable come resistance to the first-generation drugs are in clinical trials, and drugs targeting the immune system are showing activity in patients. This extraordinary promise is tempered by the sobering fact that even the newest treatments for metastatic disease are rarely curative and are effective only in a small fraction of all patients. Thus, ongoing and future efforts to find new vulnerabilities of lung cancers unravel the complexity of drug resistance, increase the efficacy of immunotherapies, and perform biomarker-driven clinical trials are necessary to improve the outcome of lung cancer patients.

Novel PEI/Poly-γ-Gutamic Acid Nanoparticles for High Efficient siRNA and Plasmid DNA Co-Delivery

The efficient delivery of sufficient amounts of nucleic acids into target cells is critical for successful gene therapy and gene knockdown. The DNA/siRNA co-delivery system has been considered a promising approach for cancer therapy to simultaneously express and inhibit tumor suppressor genes and overexpressed oncogenes, respectively, triggering synergistic anti-cancer effects. Polyethylenimine (PEI) has been identified as an efficient non-viral vector for transgene expression. In this study, we created a very high efficient DNA/siRNA co-delivery system by incorporating a negatively-charged poly-γ-glutamic acid (γ-PGA) into PEI/nucleic acid complexes. Spherical nanoparticles with about 200 nm diameter were formed by mixing PEI/plasmid DNA/siRNA/γ-PGA (dual delivery nanoparticles; DDNPs) with specific ratio (N/P/C ratio) and the particles present positive surface charge under all manufacturing conditions. The gel retardation assay shows both nucleic acids were effectively condensed by PEI, even at low N/P ratios. The PEI-based DDNPs reveal excellent DNA/siRNA transfection efficiency in the human hepatoma cell line (Hep 3B) by simultaneously providing high transgene expression efficiency and high siRNA silencing effect. The results indicated that DDNP can be an effective tool for gene therapy against hepatoma.

Potential applications of nanoparticles in cancer immunotherapy

In recent years considerable progress has been made in the field of cancer immunotherapy whereby treatments that modulate the body's own immune system are used to combat cancer. This has the potential to not only elicit strong anti-cancer immune responses which can break pre-existing tolerance and help promote tumor regression, but could also induce immunological memory which may help prevent tumor recurrence. In order to ensure effective delivery of immunotherapeutic agents, such as vaccines, checkpoint inhibitors, chemotherapeutic agents and nucleic acids, a safe and effective delivery system is often required. One such approach is the use of multifunctional nanoparticles (NPs), such as liposomes, polymers, micelles, dendrimers, inorganic NPs, and hybrid NPs, which have the potential to combine the delivery of a diverse range of therapeutic immunomodulators thereby increasing the efficacy of tumor cell killing. This review focuses on recent progress in NP-mediated immunotherapy for the treatment of cancer.

Effective Delivery of Male Contraceptives Behind the Blood-Testis Barrier (BTB) - Lesson from Adjudin

The blood-testis barrier (BTB) is one of the tightest blood-tissue barriers in the mammalian body. It divides the seminiferous epithelium of the seminiferous tubule, the functional unit of the testis, where spermatogenesis takes place, into the basal and the adluminal (apical) compartments. Functionally, the BTB provides a unique microenvironment for meiosis I/II and post-meiotic spermatid development which take place exclusively in the apical compartment, away from the host immune system, and it contributes to the immune privilege status of testis. However, the BTB also poses major obstacles in developing male contraceptives (e.g., adjudin) that exert their effects on germ cells in the apical compartment, such as by disrupting spermatid adhesion to the Sertoli cell, causing germ cell exfoliation from the testis. Besides the tight junction (TJ) between adjacent Sertoli cells at the BTB that restricts the entry of contraceptives from the microvessels in the interstitium to the adluminal compartment, drug transporters, such as P-glycoprotein and multidrug resistance-associated protein 1 (MRP1), are also present that actively pump drugs out of the testis, limiting drug bioavailability. Recent advances in drug formulations, such as drug particle micronization (<50 μm) and co-grinding of drug particles with ß-cyclodextrin have improved bioavailability of contraceptives via considerable increase in solubility. Herein, we discuss development in drug formulations using adjudin as an example. We also put emphasis on the possible use of nanotechnology to deliver adjudin to the apical compartment with multidrug magnetic mesoporous silica nanoparticles. These advances in technology will significantly enhance our ability to develop effective non-hormonal male contraceptives for men.

siRNA Versus miRNA as Therapeutics for Gene Silencing

Discovered a little over two decades ago, small interfering RNAs (siRNAs) and microRNAs (miRNAs) are noncoding RNAs with important roles in gene regulation. They have recently been investigated as novel classes of therapeutic agents for the treatment of a wide range of disorders including cancers and infections. Clinical trials of siRNA- and miRNA-based drugs have already been initiated. siRNAs and miRNAs share many similarities, both are short duplex RNA molecules that exert gene silencing effects at the post-transcriptional level by targeting messenger RNA (mRNA), yet their mechanisms of action and clinical applications are distinct. The major difference between siRNAs and miRNAs is that the former are highly specific with only one mRNA target, whereas the latter have multiple targets. The therapeutic approaches of siRNAs and miRNAs are therefore very different. Hence, this review provides a comparison between therapeutic siRNAs and miRNAs in terms of their mechanisms of action, physicochemical properties, delivery, and clinical applications. Moreover, the challenges in developing both classes of RNA as therapeutics are also discussed.

Development of small RNA delivery systems for lung cancer therapy

RNA interference (RNAi) has emerged as a powerful tool for studying target identification and holds promise for the development of therapeutic gene silencing. Recent advances in RNAi delivery and target selection provide remarkable opportunities for translational medical research. The induction of RNAi relies on small silencing RNAs, which affect specific messenger RNA (mRNA) degradation. Two types of small RNA molecules, small interfering RNAs (siRNAs) and microRNAs (miRNAs), have a central function in RNAi technology. The success of RNAi-based therapeutic delivery may be dependent upon uncovering a delivery route, sophisticated delivery carriers, and nucleic acid modifications. Lung cancer is still the leading cause of cancer death worldwide, for which novel therapeutic strategies are critically needed. Recently, we have reported a novel platform (PnkRNA™ and nkRNA^®) to promote naked RNAi approaches through inhalation without delivery vehicles in lung cancer xenograft models. We suggest that a new class of RNAi therapeutic agent and local drug delivery system could also offer a promising RNAi-based strategy for clinical applications in cancer therapy. In this article, we show recent strategies for an RNAi delivery system and suggest the possible clinical usefulness of RNAi-based therapeutics for lung cancer treatment.

Knockdown of STAT3 expression in SKOV3 cells by biodegradable siRNA-PLGA/CSO conjugate micelles

Biodegradable and biocompatible poly(d,l-lactic-co-glycolic acid) (PLGA)was conjugated to the 5'-thiol end of signal transducer and activator of transcription 3 (STAT3) small interfering RNA (STAT3-siRNA) via a disulfide bond. In aqueous environments, these siRNA-PLGA conjugates can spontaneously form core/shell type spherical micelles with a particle size of about 200 nm. A biodegradable, low molecular weight cationic polymer, chitosan oligosaccharide (CSO), was added to the siRNA-PLGA micelles at different nitrogen to phosphate (N/P) ratios to form stable, spherical siRNA-PLGA/CSO micelles with sizes of 150-180 nm. The siRNA-PLGA/CSO micelles were produced via ionic complexation between negatively charged siRNA and positively charged CSO on the outer shell of the micelles. The siRNA-PLGA/CSO micelles exhibited superior cellular uptake and STAT3 gene silencing efficiency in SKOV3 ovarian cancer cells when compared with siRNA/CSO complexes at the same N/P ratios with no significant differences with lipofectamine 2000. Furthermore, the siRNA-PLGA/CSO micelles showed that the efficiencies of cellular uptake and STAT3 gene silencing gradually increased with increasing N/P ratios. The siRNA-PLGA/CSO micelles also inhibited the growth of SKOV3 cells, as well as, promoted apoptosis of the cells. These results indicate that siRNA-PLGA/CSO micelles can be utilized as a novel and efficient siRNA carrier to treat a variety of diseases.

Hybrid poly(lactic-co-glycolic acid) nanoparticles: design and delivery prospectives

Poly(lactic-co-glycolic acid) (PLGA), a US Food and Drug Administration (FDA)-approved copolymer, has been exploited widely in the design of nanoparticles because it is biodegradable, biocompatible, protects the drug molecules from degradation, and aids in producing sustained and targeted delivery. However, certain constraints associated with PLGA nanoparticles, such as poor drug encapsulation, polymer degradation, and scale-up issues, have led to the development of emerging hybrid PLGA delivery systems. These hybrid nanoparticles are core-shell nanostructures comprising either a PLGA core or a PLGA shell combining multiple functionalities within one system and, thus, exhibiting the complementary characteristics of two different platforms used for the delivery of a wide range of therapeutics and imaging.

Intratumoral injection of PKR shRNA expressing plasmid inhibits B16-F10 melanoma growth

The RNA-dependent protein kinase (PKR) is a serine/threonine kinase that is involved in the regulation of important cell processes such as apoptosis, signal transduction, cell proliferation and differentiation. However, the role played by PKR in cancer remains controversial. RNA interference (RNAi) has currently become an important technique in understanding gene function. Previously, we showed that PKR shRNA downregulates PKR expression in B16-F10 melanoma cells and reduces the metastatic potential of these tumor cells. In the present study, we examined the effect of the intratumoral injection of PKR shRNA‑expressing plasmid on the growth of B16-F10 melanoma in mice. The results showed that this treatment significantly reduced tumor growth. Thus, these findings suggested that PKR acts as a tumor suppressor, a finding that is consistent with our previous study on the experimental model of metastasis. Moreover, the results suggested that this effect may be mediated by the transcription factor NF-κB. The present study confirmed the hypothesis that the direct administration of RNAi-based therapeutics in the target tumor is a promising approach for overcoming the obstacles of systemic delivery. The results also suggested that the intratumoral injection of PKR shRNA‑expressing vector is a novel therapeutic approach for human solid tumors such as cutaneous melanoma and breast cancer, since PKR is overexpressed in these tumors.

siRNA delivery to the lung: what's new?

RNA interference (RNAi) has been thought of as the general answer to many unmet medical needs. After the first success stories, it soon became obvious that short interfering RNA (siRNA) is not suitable for systemic administration due to its poor pharmacokinetics. Therefore local administration routes have been adopted for more successful in vivo RNAi. This paper reviews nucleic acid modifications, nanocarrier chemistry, animal models used in successful pulmonary siRNA delivery, as well as clinical translation approaches. We summarize what has been published recently and conclude with the potential problems that may still hamper the efficient clinical application of RNAi in the lung.