Short interfering RNAs as a tool for cancer gene therapy

Gold nanostructure-mediated delivery of anticancer agents: Biomedical applications, reversing drug resistance, and stimuli-responsive nanocarriers

The application of nanoarchitectures in cancer therapy seems to be beneficial for the delivery of antitumor drugs. In recent years, attempts have been made to reverse drug resistance, one of the factors threatening the lives of cancer patients worldwide. Gold nanoparticles (GNPs) are metal nanostructures with a variety of advantageous properties, such as tunable size and shape, continuous release of chemicals, and simple surface modification. This review focuses on the application of GNPs for the delivery of chemotherapy agents in cancer therapy. Utilizing GNPs results in targeted delivery and increased intracellular accumulation. Besides, GNPs can provide a platform for the co-delivery of anticancer agents and genetic tools with chemotherapeutic compounds to exert a synergistic impact. Furthermore, GNPs can promote oxidative damage and apoptosis by triggering chemosensitivity. Due to their capacity for providing photothermal therapy, GNPs can enhance the cytotoxicity of chemotherapeutic agents against tumor cells. The pH-, redox-, and light-responsive GNPs are beneficial for drug release at the tumor site. For the selective targeting of cancer cells, surface modification of GNPs with ligands has been performed. In addition to improving cytotoxicity, GNPs can prevent the development of drug resistance in tumor cells by facilitating prolonged release and loading low concentrations of chemotherapeutics while maintaining their high antitumor activity. As described in this study, the clinical use of chemotherapeutic drug-loaded GNPs is contingent on enhancing their biocompatibility.

Why is Mortalin a Potential Therapeutic Target for Cancer?

Cancer is one of the leading causes of death worldwide, accounting for nearly 10 million deaths in 2020. Therefore, cancer therapy is a priority research field to explore the biology of the disease and identify novel targets for the development of better treatment strategies. Mortalin is a member of the heat shock 70 kDa protein family. It is enriched in several types of cancer and contributes to carcinogenesis in various ways, including inactivation of the tumor suppressor p53, deregulation of apoptosis, induction of epithelial–mesenchymal transition, and enhancement of cancer stemness. It has been studied extensively as a therapeutic target for cancer treatment, and several types of anti-mortalin molecules have been discovered that effectively suppress the tumor cell growth. In this review, we 1) provide a comprehensive sketch of the role of mortalin in tumor biology; 2) discuss various anti-mortalin molecules, including natural compounds, synthetic small molecules, peptides, antibodies, and nucleic acids, that have shown potential for cancer treatment in laboratory studies; and 3) provide future perspectives in cancer treatment.

ErbB3-Targeting Oncolytic Adenovirus Causes Potent Tumor Suppression by Induction of Apoptosis in Cancer Cells

Cancer is a multifactorial and deadly disease. Despite major advancements in cancer therapy in the last two decades, cancer incidence is on the rise and disease prognosis still remains poor. Furthermore, molecular mechanisms of cancer invasiveness, metastasis, and drug resistance remain largely elusive. Targeted cancer therapy involving the silencing of specific cancer-enriched proteins by small interfering RNA (siRNA) offers a powerful tool. However, its application in clinic is limited by the short half-life of siRNA and warrants the development of efficient and stable siRNA delivery systems. Oncolytic adenovirus-mediated therapy offers an attractive alternative to the chemical drugs that often suffer from innate and acquired drug resistance. In continuation to our reports on the development of oncolytic adenovirus-mediated delivery of shRNA, we report here the replication-incompetent (dAd/shErbB3) and replication-competent (oAd/shErbB3) oncolytic adenovirus systems that caused efficient and persistent targeting of ErbB3. We demonstrate that the E1A coded by oAd/shErbB, in contrast to dAd/shErbB, caused downregulation of ErbB2 and ErbB3, yielding stronger downregulation of the ErbB3-oncogenic signaling axis in in vitro models of lung and breast cancer. These results were validated by in vivo antitumor efficacy of dAd/shErbB3 and oAd/shErbB3.

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

Albumin Nanostructures for Nucleic Acid Delivery in Cancer: Current Trend, Emerging Issues, and Possible Solutions

Cancer is one of the major health problems worldwide, and hence, suitable therapies with enhanced efficacy and reduced side effects are desired. Gene therapy, involving plasmids, small interfering RNAs, and antisense oligonucleotides have been showing promising potential in cancer therapy. In recent years, the preparation of various carriers for nucleic acid delivery to the tumor sites is gaining attention since intracellular and extracellular barriers impart major challenges in the delivery of naked nucleic acids. Albumin is a versatile protein being used widely for developing carriers for nucleic acids. It provides biocompatibility, tumor specificity, the possibility for surface modification, and reduces toxicity. In this review, the advantages of using nucleic acids in cancer therapy and the challenges associated with their delivery are presented. The focus of this article is on the different types of albumin nanocarriers, such as nanoparticles, polyplexes, and nanoconjugates, employed to overcome the limitations of the direct use of nucleic acids in vivo. This review also highlights various approaches for the modification of the surface of albumin to enhance its transfection efficiency and targeted delivery in the tumor sites.

Nanomedicines for Endometriosis: Lessons Learned from Cancer Research

Endometriosis is an incurable gynecological disease characterized by the abnormal growth of endometrium-like tissue, characteristic of the uterine lining, outside of the uterine cavity. Millions of people with endometriosis suffer from pelvic pain and infertility. This review aims to discuss whether nanomedicines that are promising therapeutic approaches for various diseases have the potential to create a paradigm shift in endometriosis management. For the first time, the available reports and achievements in the field of endometriosis nanomedicine are critically evaluated, and a summary of how nanoparticle-based systems can improve endometriosis treatment and diagnosis is provided. Parallels between cancer and endometriosis are also drawn to understand whether some fundamental principles of the well-established cancer nanomedicine field can be adopted for the development of novel nanoparticle-based strategies for endometriosis. This review provides the state of the art of endometriosis nanomedicine and perspective for researchers aiming to realize and exploit the full potential of nanoparticles for treatment and imaging of the disorder.

Strategies to better treat glioblastoma: antiangiogenic agents and endothelial cell targeting agents

Glioblastoma multiforme (GBM) is the most prevalent and aggressive form of glioma, with poor prognosis and high mortality rates. As GBM is a highly vascularized cancer, antiangiogenic therapies to halt or minimize the rate of tumor growth are critical to improving treatment. In this review, antiangiogenic therapies, including small-molecule drugs, nucleic acids and proteins and peptides, are discussed. The authors further explore biomaterials that have been utilized to increase the bioavailability and bioactivity of antiangiogenic factors for better antitumor responses in GBM. Finally, the authors summarize the current status of biomaterial-based targeting moieties that target endothelial cells in GBM to more efficiently deliver therapeutics to these cells and avoid off-target cell or organ side effects.

A library of aminoglycoside-derived lipopolymer nanoparticles for delivery of small molecules and nucleic acids

Simultaneous delivery of small molecules and nucleic acids using a single vehicle can lead to novel combination treatments and multifunctional carriers for a variety of diseases. In this study, we report a novel library of aminoglycoside-derived lipopolymers nanoparticles (LPNs) for the simultaneous delivery of different molecular cargoes including nucleic acids and small-molecules. The LPN library was screened for transgene expression efficacy following delivery of plasmid DNA, and lead LPNs that showed high transgene expression efficacies were characterized using hydrodynamic size, zeta potential, 1H NMR and FT-IR spectroscopy, and transmission electron microscopy. LPNs demonstrated significantly higher efficacies for transgene expression than 25 kDa polyethyleneamine (PEI) and lipofectamine, including in presence of serum. Self-assembly of these cationic lipopolymers into nanoparticles also facilitated the delivery of small molecule drugs (e.g. doxorubicin) to cancer cells. LPNs were also employed for the simultaneous delivery of the small-molecule histone deacetylase (HDAC) inhibitor AR-42 together with plasmid DNA to cancer cells as a combination treatment approach for enhancing transgene expression. Taken together, our results indicate that aminoglycoside-derived LPNs are attractive vehicles for simultaneous delivery of imaging agents or chemotherapeutic drugs together with nucleic acids for different applications in medicine and biotechnology.

Dual MicroRNA-Triggered Drug Release System for Combined Chemotherapy and Gene Therapy with Logic Operation

Combination therapy via stimulus-responsive drug release is known to improve treatment efficacy and minimize side effects. However, the use of low-abundance cancer biomarkers as molecular triggers to induce efficient drug release for combination therapy still remains a challenge. Herein, we developed a dual microRNA-responsive drug nanocarrier for catalytic release of doxorubicin (Dox) and small interfering RNA (siRNA) in cancerous cells for combined chemotherapy and gene therapy with logic operation. The nanocarrier is constructed by assembling two duplexes of DNA/RNA and Dox molecules onto DNA-functionalized gold nanoparticles. Two microRNA molecules (miRNA-21 and miRNA-10b overexpressed in MDA-MB-231) could alternatively catalyze the disassembly of the nanocarrier through a thermodynamically driven entropy gain process, during which Dox molecules are released, and the two pairs of released DNA/RNA duplex hybridize to generate siRNA (siBcl-2) in situ by strand displacement reactions. Quantum dots are used to track the process in living cells. The AND logic gate-based drug release system allows effective treatment of specific cancer cell types according to miRNA expression patterns. This strategy represents an effective means to overcome multidrug resistance and improve therapeutic effects.

Recent Advances in Subcellular Targeted Cancer Therapy Based on Functional Materials

Recently, diverse functional materials that take subcellular structures as therapeutic targets are playing increasingly important roles in cancer therapy. Here, particular emphasis is placed on four kinds of therapies, including chemotherapy, gene therapy, photodynamic therapy (PDT), and hyperthermal therapy, which are the most widely used approaches for killing cancer cells by the specific destruction of subcellular organelles. Moreover, some non-drug-loaded nanoformulations (i.e., metal nanoparticles and molecular self-assemblies) with a fatal effect on cells by influencing the subcellular functions without the use of any drug molecules are also included. According to the basic principles and unique performances of each treatment, appropriate strategies are developed to meet task-specific applications by integrating specific materials, ligands, as well as methods. In addition, the combination of two or more therapies based on multifunctional nanostructures, which either directly target specific subcellular organelles or release organelle-targeted therapeutics, is also introduced with the intent of superadditive therapeutic effects. Finally, the related challenges of critical re-evaluation of this emerging field are presented.

FABP7 promotes cell proliferation and survival in colon cancer through MEK/ERK signaling pathway

Colon cancer (CC), one of the most frequently diagnosed malignancies deriving from the digestive system, has greatly threatened human health and life. Fatty acid binding protein 7 (FABP7), an intracellular protein with the tissue-specific expression pattern, has been reported to be implicated in diverse types of human tumors. However, the biological role of FABP7 in CC is still poorly understood. The current study aimed to investigate the role of FABP7 in CC and illuminate the potential molecular mechanisms. In this present study, we found that FABP7 was highly expressed in CC tissues and cell lines, suggesting the possible involvement of FABP7 in CC tumorigenesis. Moreover, functional investigations showed that FABP7-overexpression promoted CC cell proliferation, colony formation, cell cycle progression and inhibited cell apoptosis; on the contrary, FABP7 knockdown produced an inhibitory effects on CC cell proliferation and survival. Notably, FABP7 knockdown inhibited colon tumor growth in vivo. In addition, mechanistic investigations demonstrated that FABP7 exerted its promoting effects on CC cell proliferation and survival through activation of the MEK/ERK signaling pathway. Collectively, our data indicate that FABP7 may be used as a novel diagnostic bio-marker and a potential therapeutic target for CC.

Enhanced Delivery of Therapeutic siRNA into Glioblastoma Cells Using Dendrimer-Entrapped Gold Nanoparticles Conjugated with β-Cyclodextrin

We describe a safe and highly effective non-viral vector system based on β-cyclodextrin (β-CD)-modified dendrimer-entrapped gold nanoparticles (Au DENPs) for improved delivery small interfering RNA (siRNA) to glioblastoma cells. In our approach, we utilized amine-terminated generation 5 poly(amidoamine) dendrimers partially grafted with β-CD as a nanoreactor to entrap Au NPs. The acquired β-CD-modified Au DENPs (Au DENPs-β-CD) were complexed with two different types of therapeutic siRNA (B-cell lymphoma/leukemia-2 (Bcl-2) siRNA and vascular endothelial growth factor (VEGF) siRNA). The siRNA compression ability of the Au DENPs-β-CD was evaluated by various methods. The cytocompatibility of the vector/siRNA polyplexes was assessed by viability assay of cells. The siRNA transfection capability of the formed Au DENPs-β-CD vector was evaluated by flow cytometric assay of the cellular uptake of the polyplexes and Western blot assays of the Bcl-2 and VEGF protein expression. Our data reveals that the formed Au DENPs-β-CD carrier enables efficiently delivery of siRNA to glioma cells, has good cytocompatibility once complexed with the siRNA, and enables enhanced gene silencing to inhibit the expression of Bcl-2 and VEGF proteins. The developed Au DENPs-β-CD vector may be used for efficient siRNA delivery to different biosystems for therapeutic purposes.

Bright-field in situ hybridization detects gene alterations and viral infections useful for personalized management of cancer patients

INTRODUCTION

Bright-field in situ hybridization (ISH) methods detect gene alterations that may improve diagnostic precision and personalized management of cancer patients. Areas covered: This review focuses on some bright-field ISH techniques for detection of gene amplification or viral infection that have already been introduced in tumor pathology, research and diagnostic practice. Other emerging ISH methods, for the detection of translocation, mRNA and microRNA have recently been developed and need both an optimization and analytical validation. The review also deals with their clinical applications and implications on the management of cancer patients. Expert commentary: The technology of bright-field ISH applications has advanced significantly in the last decade. For example, an automated dual-color assay was developed as a clinical test for selecting cancer patients that are candidates for personalized therapy. Recently an emerging bright-field gene-protein assay has been developed. This method simultaneously detects the protein, gene and centromeric targets in the context of tissue morphology, and might be useful in assessing the HER2 status particularly in equivocal cases or samples with heterogeneous tumors. The application of bright-field ISH methods has become the gold standard for the detection of tumor-associated viral infection as diagnostic or prognostic factors.

PNT2258, a novel deoxyribonucleic acid inhibitor, induces cell cycle arrest and apoptosis via a distinct mechanism of action: a new class of drug for non-Hodgkin's lymphoma

Current therapy for BCL-2-associated tumors such as Non-Hodgkin Lymphomas (NHL) is inadequate. The DNAi PNT2258, a 24 base single-stranded phosphodiester DNA oligodeoxynucleotide (PNT100) encapsulated in a protective liposome, was precisely designed to treat cancers that over-express BCL-2. PNT2258 strongly inhibited BCL-2 promoter activity, confirming its predicted mechanism of action. BCL-2 mRNA and protein expression were significantly downregulated in a follicular small cleaved cell lymphoma (WSU-FSCCL) cell line. 2.5μM PNT2258 induced an initial S- phase arrest followed by a gradual increase in the sub-G0 (apoptosis) compartment and a reciprocal progressive decrease of the S phase. Terminal deoxynucleotidyl transferase (TdT)-positive populations and cleaved caspase-3 and PARP were also increased. The data are consistent with the idea that BCL-2 inhibition by PNT2258 activates apoptotic pathways in WSU-FSCCL cells. This is the first report to address the distinct mechanism of action underlying the anti-BCL-2 functions of PNT2258. Growth inhibition in two other cell lines, WSU-DLCL2 and WSU-WM, supports broad applicability of BCL-2 DNAi to treatment of B-cell NHL.

RNA Interference-Mediated Gene Silencing in Esophageal Adenocarcinoma

RNA interference (RNAi) is a normal physiological mechanism in which a short effector antisense RNA molecule regulates target gene expression. It is a powerful tool to silence a particular gene of interest in a sequence-specific manner and can be used to target against various molecular pathways in esophageal adenocarcinoma by designing RNAi targeting key pathogenic genes. RNAi-based therapeutics against esophageal adenocarcinoma can be developed using different strategies including inhibition of overexpressed oncogenes, blocking cell division by interfering cyclins and related genes or enhancing apoptosis by suppressing anti-apoptotic genes. In addition, RNAi against multidrug resistance genes or chemo-resistance targets may provide promising cancer therapeutic options. Here, we describe RNAi technology using MET, a proto-oncogene in esophageal adenocarcinoma cells, as a model target. Lentiviral particles expressing MET shRNA was used to silence MET genes. Then, Western blot analysis was performed to confirm MET knockdown.

Effects of Grb2-associated binding protein 2-specific siRNA on the migration and invasion of MG-63 osteosarcoma cells

To investigate the association between the expression of growth factor receptor binding protein 2-associated binding protein 2 (Gab2) in human osteosarcoma as well as the effects of Gab2 on invasion and metastasis, human MG-63 osteosarcoma cells were transfected with small interfering (si)RNA plasmid. Gab2 protein and mRNA expression levels were detected using western blotting and reverse transcription-polymerase chain reaction, respectively. The cell migration and invasion abilities were detected using in vitro chemotaxis and invasion assays, respectively, following siRNA vector expression. Gab2 was markedly expressed in MG-63 cells. The Gab2 protein and mRNA expression levels of the cells transfected with Gab2 siRNA (siGab2/MG-63) were reduced compared with those of the cells transfected with scrambled siRNA (Scr/MG-63). The chemotaxis assay demonstrated that the migration capacity of siGab2/MG-63 cells induced by 10 µg/l epidermal growth factor, was significantly reduced compared with that of the MG-63 and Scr/MG-63 cells (P<0.01). In comparison with Scr/MG-63 and MG-63 cells, a reduced number of siGab2/MG-63 cells invaded the Matrigel matrix, demonstrating that the in vitro invasion capacity was significantly decreased (P<0.01). Decreasing Gab2 expression levels using siRNA interference inhibited the migration and invasion ability of human MG-63 osteosarcoma cells.

Inhibitors of connexin and pannexin channels as potential therapeutics

While gap junctions support the exchange of a number of molecules between neighboring cells, connexin hemichannels provide communication between the cytosol and the extracellular environment of an individual cell. The latter equally holds true for channels composed of pannexin proteins, which display an architecture reminiscent of connexin hemichannels. In physiological conditions, gap junctions are usually open, while connexin hemichannels and, to a lesser extent, pannexin channels are typically closed, yet they can be activated by a number of pathological triggers. Several agents are available to inhibit channels built up by connexin and pannexin proteins, including alcoholic substances, glycyrrhetinic acid, anesthetics and fatty acids. These compounds not always strictly distinguish between gap junctions, connexin hemichannels and pannexin channels, and may have effects on other targets as well. An exception lies with mimetic peptides, which reproduce specific amino acid sequences in connexin or pannexin primary protein structure. In this paper, a state-of-the-art overview is provided on inhibitors of cellular channels consisting of connexins and pannexins with specific focus on their mode-of-action and therapeutic potential.

Sustained expression of miR-26a promotes chromosomal instability and tumorigenesis through regulation of CHFR

MicroRNA 26a (miR-26a) reduces cell viability in several cancers, indicating that miR-26a could be used as a therapeutic option in patients. We demonstrate that miR-26a not only inhibits G1-S cell cycle transition and promotes apoptosis, as previously described, but also regulates multiple cell cycle checkpoints. We show that sustained miR-26a over-expression in both breast cancer (BC) cell lines and mouse embryonic fibroblasts (MEFs) induces oversized cells containing either a single-large nucleus or two nuclei, indicating defects in mitosis and cytokinesis. Additionally, we demonstrate that miR-26a induces aneuploidy and centrosome defects and enhances tumorigenesis. Mechanistically, it acts by targeting G1-S transition genes as well as genes involved in mitosis and cytokinesis such as CHFR, LARP1 and YWHAE. Importantly, we show that only the re-expression of CHFR in miR-26a over-expressing cells partially rescues normal mitosis and impairs the tumorigenesis exerted by miR-26a, indicating that CHFR represents an important miR-26a target in the regulation of such phenotypes. We propose that miR-26a delivery might not be a viable therapeutic strategy due to the potential deleterious oncogenic activity of this miRNA.

Nucleolin-targeted Extracellular Vesicles as a Versatile Platform for Biologics Delivery to Breast Cancer

Small interfering RNAs (siRNA)/microRNAs (miRNA) have promising therapeutic potential, yet their clinical application has been hampered by the lack of appropriate delivery systems. Herein, we employed extracellular vesicles (EVs) as a targeted delivery system for small RNAs. EVs are cell-derived small vesicles that participate in cell-to-cell communication for protein and RNA delivery. We used the aptamer AS1411-modified EVs for targeted delivery of siRNA/microRNA to breast cancer tissues. Tumor targeting was facilitated via AS1411 binding to nucleolin, which is highly expressed on the surface membrane of breast cancer cells. This delivery vesicle targeted let-7 miRNA delivery to MDA-MB-231 cells in vitro as confirmed with fluorescent microscopic imaging and flow cytometry. Also, intravenously delivered AS1411-EVs loaded with miRNA let-7 labeled with the fluorescent marker, Cy5, selectively targeted tumor tissues in tumor-bearing mice and inhibited tumor growth. Importantly, the modified EVs were well tolerated and showed no evidence of nonspecific side effects or immune response. Thus, the RNAi nanoplatform is versatile and can deliver siRNA or miRNA to breast cancer cells both in vitro and in vivo. Our results suggest that the AS1411-EVs have a great potential as drug delivery vehicles to treat cancers.

Type I Interferons Impede Short Hairpin RNA-Mediated RNAi via Inhibition of Dicer-Mediated Processing to Small Interfering RNA

RNAi by short hairpin RNA (shRNA) is a powerful tool not only for studying gene functions in various organisms, including mammals, but also for the treatment of severe disorders. However, shRNA-expressing vectors can induce type I interferon (IFN) expression by activation of innate immune responses, leading to off-target effects and unexpected side effects. Several strategies have been developed to prevent type I IFN induction. On the other hand, it has remained unclear whether type I IFNs have effects on shRNA-mediated RNAi. Here, we show that the type I IFNs significantly inhibit shRNA-mediated RNAi. Treatment with recombinant human IFN-α significantly inhibited shRNA-mediated knockdown of target genes, while it did not inhibit small interfering RNA (siRNA)-mediated knockdown. Following treatment with IFN-α, increased and decreased copy numbers of shRNA and its processed form, respectively, were found in the cells transfected with shRNA-expressing plasmids. Dicer protein levels were not altered by IFN-α. These results indicate that type I IFNs inhibit shRNA-mediated RNAi via inhibition of dicer-mediated processing of shRNA to siRNA. Our findings should provide important clues for efficient RNAi-mediated knockdown of target genes in both basic researches and clinical gene therapy.

Effects of RNA silencing of matrix metalloproteinase-2 on the growth of esophageal carcinoma cells in vivo

Esophageal carcinoma is one of the most common malignancies in China. Previous studies reported that matrix metalloproteinases (MMPs) have important roles in the progression and invasion of numerous types of solid tumors. Among the MMPs, MMP-2 has been closely associated with tumor growth and invasion. In the present study, a short hairpin RNA (shRNA) lentiviral expression vector targeting the MMP-2 gene was constructed in order to observe the inhibitory effect of MMP-2 gene silencing on the growth of the KYSE150 esophageal carcinoma cell line in vivo. Three small hairpin RNA sequences targeting MMP-2 were designed and cloned into lentiviral vectors. Following transfection of the lentiviral vectors into KTSE150 cells, MMP-2 mRNA and protein expression levels were examined by reverse transcription-quantitative polymerase chain reaction and western blotting, and the growth rate of cells was analyzed by MTT assays. Subsequently, tumor growth was assessed in nude mice. Lentivirus-mediated RNA interference effectively inhibited the expression of MMP-2 mRNA and protein in KYSE150 esophageal carcinoma cells, and suppressed the growth of esophageal carcinoma cells in vivo. The results of the present study suggested that lentivirus-mediated gene therapy targeting MMP-2 may be an attractive strategy for the treatment of esophageal carcinoma and justifies the performance of further studies on the application of lentivirus vectors to cancer gene therapy.

Lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of the Epstein-Barr-associated gastric carcinoma cell line GT38 in vitro

In this study, lentivirus-mediated RNA interference (RNAi) was applied to inhibit latent membrane protein 2A (LMP2A) gene expression, in order to explore the effects of LMP2A silencing on the growth of an Epstein-Barr virus-associated gastric carcinoma (EBVaGC) cell line in vitro. Lentivirus-mediated RNAi technology was employed to specifically knock down the LMP2A gene in the EBV-positive gastric carcinoma cell line GT38. After infection, reverse transcription-quantitative polymerase chain reaction, western blotting, flow cytometry and colony formation assays were conducted to evaluate the expression of LMP2A and the biological behavior of the GT38 cell line in vitro. The results showed that the expression of the LMP2A gene was clearly downregulated in the infected cells, which indicated that a highly efficient and stable lentivirus vector was successfully constructed. In the GT38 cells in which the expression of LMP2A was downregulated, the proliferation and colony formation of the cells was significantly inhibited. In addition, it was found that the cell cycle of the GT38 cells was arrested in the G0/G1 phase and the apoptosis rate was increased. These results indicate that lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of the EBVaGC cell line GT38 in vitro, and suggests that LMP2A is a potential target for gene therapy in the treatment of EBVaGC.

Combinations in multimodality treatments and clinical outcomes during cancer

Combination approach could be easily considered as the future of therapeutics in all pathological states including cancer. Scientists are trying different combinations in order to determine synergism among different therapeutics which ultimately helps in the improved and more efficient management of the affected patients. Combination of multi-chemotherapeutic agents, or multi-drug therapy, may be the most commonly used strategy for cancer treatment. Monotherapy causes drug resistance and loses its response in patients after several cycles of treatment. While combining different anticancer drugs together for cancer treatment, as in the case of the cocktail therapy for HIV, not only overcomes the drug resistance but also leads to a synergistic effect, therefore showing prolonged survival for patients. The present review article is focused on different combinations in use for better efficiency of therapeutics against cancer. We searched the electronic database PubMed for pre-clinical as well as clinical controlled trials reporting diagnostic as well as therapeutic advances of various combinations in cancer. It was observed clearly that combination approach is better in various aspects including increase in efficacy, specificity and decline in the unwanted side effects.

Reversal of multidrug resistance in breast cancer MCF-7/ADR cells by h-R3-siMDR1-PAMAM complexes

Multidrug resistance (MDR) among breast cancer cells is the paramount obstacle for the successful chemotherapy. In this study, anti-EGFR antibody h-R3 was designed to self-assembled h-R3-siRNA-PAMAM-complexes (HSPCs) via electrostatic interactions for siRNA delivery. The physicochemical characterization, cell uptake, MDR1 silencing efficiency, cell migration, cell growth and cell apoptosis were investigated. The HSPCs presented lower cytotoxicity, higher cellular uptake and enhanced endosomal escape ability. Also, HSPCs encapsulating siMDR1 knockdowned 99.4% MDR1 gene with up to ∼6 times of enhancement compared to naked siMDR1, increased the doxorubicin accumulation, down-regulated P-glycoprotein (P-gp) expression and suppressed cellular migration in breast cancer MCF-7/ADR cells. Moreover, the combination of anticancer drug paclitaxel (PTX) and siMDR1 loaded HSPCs showed synergistic effect on overcoming MDR, which inhibited cell growth and induced cell apoptosis. This h-R3-mediated siMDR1 delivery system could be a promising vector for effective siRNA therapy of drug resistant breast cancer.

Hematologic malignancies: newer strategies to counter the BCL-2 protein

INTRODUCTION

BCL-2 is the founding member of the BCL-2 family of apoptosis regulatory proteins that either induce (pro-apoptotic) or inhibit (anti-apoptotic) apoptosis. The anti-apoptotic BCL-2 is classified as an oncogene, as damage to the BCL-2 gene has been shown to cause a number of cancers, including lymphoma. Ongoing research has demonstrated that disruption of BCL-2 leads to cell death. BCL-2 is also known to be involved in the development of resistance to chemotherapeutic agents, further underscoring the importance of targeting the BCL-2 gene in cancer therapeutics. Thus, numerous approaches have been developed to block or modulate the production of BCL-2 at the RNA level using antisense oligonucleotides or at the protein level with BCL-2 inhibitors, such as the novel ABT737.

METHODS

In this article, we briefly review previous strategies to target the BCL-2 gene and focus on a new approach to silence DNA, DNA interference (DNAi).

RESULTS AND CONCLUSION

DNA interference is aimed at blocking BCL-2 gene transcription. Evaluations of this technology in preclinical and early clinical studies are very encouraging and strongly support further development of DNAi as cancer therapeutics. A pilot phase II clinical trial in patients with relapsed or refractory non-Hodgkin lymphoma, PNT2258 demonstrated clinical benefit in 11 of 13 patients with notable responses in diffuse large B cell lymphoma and follicular lymphoma. By targeting the DNA directly, the DNAi technology promises to be more effective compared with other gene-interference strategies that target the RNA or protein but leaves the dysregulated DNA functional.

Nucleic Acid Bioconjugates in Cancer Detection and Therapy

Nucleoside- and nucleotide-based chemotherapeutics have been used to treat cancer for more than 50 years. However, their inherent cytotoxicities and the emergent resistance of tumors against treatment has inspired a new wave of compounds in which the overall pharmacological profile of the bioactive nucleic acid component is improved by conjugation with delivery vectors, small-molecule drugs, and/or imaging modalities. In this manner, nucleic acid bioconjugates have the potential for targeting and effecting multiple biological processes in tumors, leading to synergistic antitumor effects. Consequently, tumor resistance and recurrence is mitigated, leading to more effective forms of cancer therapy. Bioorthogonal chemistry has led to the development of new nucleoside bioconjugates, which have served to improve treatment efficacy en route towards FDA approval. Similarly, oligonucleotide bioconjugates have shown encouraging preclinical and clinical results. The modified oligonucleotides and their pharmaceutically active formulations have addressed many weaknesses of oligonucleotide-based drugs. They have also paved the way for important advancements in cancer diagnosis and treatment. Cancer-targeting ligands such as small-molecules, peptides, and monoclonal antibody fragments have all been successfully applied in oligonucleotide bioconjugation and have shown promising anticancer effects in vitro and in vivo. Thus, the application of bioorthogonal chemistry will, in all likelihood, continue to supply a promising pipeline of nucleic acid bioconjugates for applications in cancer detection and therapy.

Silencing Matrix Metalloproteinases 9 and 2 Inhibits Human Retinal Microvascular Endothelial Cell Invasion and Migration

PURPOSE

Proliferative retinal angiogenesis may severely impair the retina. Previous studies have indicated that matrix metalloproteinase (MMP)-2 and MMP-9 play important roles in the process of retinal angiogenesis. In this study, we suppressed MMP-2 and MMP-9 expression with RNA interference (RNAi) and then observed the inhibitory effects on the invasion and migration of human retinal microvascular endothelial cells (HRMECs).

METHODS

Small interfering RNAs against MMP-2 mRNA and MMP-9 mRNA were synthesized. After transfection, the MMP-2 and MMP-9 expression in HRMECs was examined by real-time polymerase chain reaction and Western blot analysis. Cell migration and invasion were measured with a migration assay and a scratch wound assay, respectively.

RESULTS

RNAi against MMP-2 and MMP-9 successfully inhibited the mRNA and protein expression of MMP-2 and MMP-9 in HRMECs. MMP-2 and MMP-9 knockdown could inhibit the invasion and migration of HRMECs.

CONCLUSIONS

These findings suggest that the RNAi approach towards MMP-2 and MMP-9 may be a potentially effective therapeutic method for the treatment of proliferative retinal angiogenesis.

MicroRNA-126 suppresses proliferation of undifferentiated (BRAF(V600E) and BRAF(WT)) thyroid carcinoma through targeting PIK3R2 gene and repressing PI3K-AKT proliferation-survival signalling pathway

BACKGROUND

The objectives of this study are to investigate the expression of miR-126 and evaluate its effect on proliferation in undifferentiated thyroid carcinoma.

METHODS

miR-126 expression of undifferentiated thyroid carcinoma cell lines 8505C (BRAF(V600E/V600E)), BHT-101 (BRAF(V600E/WT)) and MB-1 (BRAF(WT/WT)) were quantified with q-PCR. These cell lines were transiently transfected with exogenous miR-126 (mimic). Following transfection, proliferation effects were observed through MTS proliferation assay and colony formation abilities. Immunofluorescence imaging and Western blot assay were also done to check target proteins expression.

RESULTS

Under-expression (p<0.05) of miR-126 was noted in BRAF(V600E) mutated undifferentiated thyroid carcinoma cells (8505C and BHT-101), but no change in expression was noted in non BRAF(V600E) mutated undifferentiated thyroid carcinoma cells (MB-1). In addition, a 30-50% drop in proliferation ability and a 35-45% reduction in colony formation capability were noticed in miR-126 mimic transfected group when compared to control group. Furthermore, immunofluorescence images showed reduced expression of p85β and p-AKT protein in miR-126 mimic transfected cells when compared to un-transfected cells. Also, Western blot analysis revealed a 34-40% suppression of p85β protein and a 21-53% drop in active AKT kinase (p-AKT) protein in miR-126 mimic transfected group when compared to control group.

CONCLUSIONS

Expression of miR-126 was down-regulated in BRAF(V600E) mutated undifferentiated thyroid carcinoma. In addition, miR-126 was found to act as proliferation suppressor targeting PIK3R2 gene and reducing p85β (a regulatory subunit of PI3K kinase) protein translation and lower AKT kinase activity. Therefore, miR-126 could be a potential therapeutic tool in the treatment of undifferentiated thyroid carcinoma.

Germ cell tumors overexpress the candidate therapeutic target cyclin B1 independently of p53 function

Germ cell tumors (GCTs) generally express wild-type p53 protein. Rare p53 mutations may be associated with cisplatin resistance. There is growing interest in the role of cyclins as targets for GCTs. Cyclin B1 is involved in G2/M transition and its overexpression has been reported in tumors carrying nonfunctional p53. Conversely, cyclin B1-specific small interfering RNAs have been shown to dramatically reduce tumor proliferation. We investigated whether a subset of chemotherapy-resistant GCTs overexpressed cyclin B1 as a result of nonfunctional p53, as this would make cyclin B1 a potential therapeutic target. Our data showed that GCTs consistently overexpressed cyclin B1 independently of their responsiveness to chemotherapy or the presence of p53 mutations. Cyclin B1 was overexpressed by GCT cell lines carrying functional p53. Cyclin B1-specific small interfering RNAs only slightly reduced the proliferation of JAR and JEG-3 placental choriocarcinoma cells. Further research into targeting cyclin B1 could provide a novel intervention for GCTs.

RNA interference for epidermal growth factor receptor enhances the radiosensitivity of esophageal squamous cell carcinoma cell line Eca109

The present study investigated the effects of small interfering RNAs (siRNAs) specific to the epidermal growth factor receptor (EGFR) gene, on the radiosensitivity of esophageal squamous cell carcinoma cells. EGFR gene siRNAs (EGFR-siRNA) were introduced into esophageal cancer Eca109 cells using Lipofectamine® 2000. The EGFR messenger (m)RNA expression levels, EGFR protein expression and cell growth were assessed using reverse transcription-polymerase chain reaction analysis, western blot analysis and a Cell Counting Kit-8 (CCK-8), respectively. In addition, colony assays were used to determine the inhibitory effects of X-ray radiation on EGFR-silenced cells. EGFR mRNA and protein levels were reduced in the Eca109 cells transfected with EGFR-siRNA. The relative EGFR mRNA expression levels were reduced to 26.74, 9.52 and 4.61% in Eca109 cells transfected with EGFR-siRNA1, 2 and 3, respectively. These mRNA levels were significantly reduced compared with the those of the control group (42.44%; P<0.0001). Transfection with siRNA3 resulted in the greatest reduction in EGFR mRNA expression, with an inhibition rate of 85%. The relative EGFR protein expression levels were reduced to 24.05, 34.91 and 34.14% in Eca109 cells transfected with EGFR-siRNA1, 2 and 3, respectively. These protein levels were significantly reduced compared with those of the control group (78.57%; P<0.0001). Transfection with siRNA1 resulted in the greatest reduction in EGFR protein expression, with an inhibition rate of 72.84%. This reduction in EGFR expression inhibited the proliferation of Eca109 cells, which was identified using the CCK-8 assay. The proliferation inhibition ratio was 28.2%. The cells treated with irradiation in addition to EGFR-siRNA, demonstrated reduced radiobiological parameters (D0, Dq and SF2) compared with those of cells treated with irradiation only, with a sensitization enhancing ratio of 1.5. In conclusion, suppression of EGFR expression may enhance the radiosensitivity of esophageal cancer Eca109 cells and therefore may represent a promising approach for future clinical practice.

Overcoming multiple drug resistance by spatial-temporal synchronization of epirubicin and pooled siRNAs

One-pot solution mineralization can encapsulate epirubicin (EPI) and pooled siRNAs (Pgp and Bcl-2 siRNAs) in calcium phosphate (CaP). The resulting EPI-RNA-CaP nanocomplexes can achieve a spatial-temporal synchronous effect to full-scale overcome sophisticated multiple drug resistance (MDR) by simultaneous inhibitions of drug efflux and intracellular anti-apoptotic defense to maximize the therapeutic efficacy.

Tandem DNAzymes for mRNA cleavage: choice of enzyme, metal ions and the antisense effect

The concept of DNAzyme-based gene silencing via mRNA cleavage was proposed over twenty years ago. A number of studies regarding intracellular gene silencing have been reported as well. However, questions have been raised regarding the lack of enzyme activity in physiological buffer conditions and it is being doubted that in the previously reported studies, gene silencing might be simply due to an antisense effect. In this work, two classical DNAzymes for RNA cleavage are studied using both chimeric substrates and extracted mRNA. We concluded that the activity of the 8-17 DNAzyme is much higher than that of 10-23 in the same conditions. To illustrate and compare the effect of specific cleavage versus antisense effect in the best possible way, we used tandem DNAzymes. Specific mRNA cleavage occurred with Zn(2+), while with Mg(2+), even the inactive control DNAzymes showed a similar response, suggesting that the antisense effect might be the dominating phenomenon causing gene silencing. This study has thus clarified the choice of DNAzyme sequence, the effect of metal ions and a potential source of antisense effect.

RNAi and miRNA in viral infections and cancers

Since the first report of RNA interference (RNAi) less than a decade ago, this type of molecular intervention has been introduced to repress gene expression in vitro and also for in vivo studies in mammals. Understanding the mechanisms of action of synthetic small interfering RNAs (siRNAs) underlies use as therapeutic agents in the areas of cancer and viral infection. Recent studies have also promoted different theories about cell-specific targeting of siRNAs. Design and delivery strategies for successful treatment of human diseases are becomingmore established and relationships between miRNA and RNAi pathways have been revealed as virus-host cell interactions. Although both are well conserved in plants, invertebrates and mammals, there is also variabilityand a more complete understanding of differences will be needed for optimal application. RNA interference (RNAi) is rapid, cheap and selective in complex biological systems and has created new insight sin fields of cancer research, genetic disorders, virology and drug design. Our knowledge about the role of miRNAs and siRNAs pathways in virus-host cell interactions in virus infected cells is incomplete. There are different viral diseases but few antiviral drugs are available. For example, acyclovir for herpes viruses, alpha-interferon for hepatitis C and B viruses and anti-retroviral for HIV are accessible. Also cancer is obviously an important target for siRNA-based therapies, but the main problem in cancer therapy is targeting metastatic cells which spread from the original tumor. There are also other possible reservations and problems that might delay or even hinder siRNA-based therapies for the treatment of certain conditions; however, this remains the most promising approach for a wide range of diseases. Clearly, more studies must be done to allow efficient delivery and better understanding of unwanted side effects of siRNA-based therapies. In this review miRNA and RNAi biology, experimental design, anti-viral and anti-cancer effects are discussed.

Co-delivery of drug nanoparticles and siRNA mediated by a modified cell penetrating peptide for inhibiting cancer cell proliferation

Modified cell penetrating peptide can stabilize drug nanoparticles with improved efficacy and co-deliver siRNA inducing synergy on the inhibition of cancer cell growth.

Targeted silencing of inhibitors of apoptosis proteins with siRNAs: a potential anti-cancer strategy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies, with a very poor prognosis. Despite significant improvements in diagnosis and treatment in recent years, the long-term therapeutic efficacy is poor, partially due to tumor metastasis, recurrence, and resistance to chemo- or radio-therapy. Recently, it was found that a major feature of tumors is a combination of unrestrained cell proliferation and impaired apoptosis. There are now 8 recognized members of the IAP-family: NAIP, c-IAP1, c-IAP2, XIAP, Survivin, Bruce, Livin and ILP-2. These proteins all contribute to inhibition of apoptosis, and provide new potential avenues of cancer treatment. As a powerful tool to suppress gene expression in mammalian cells, RNAi species for inhibiting IAP genes can be directed against cancers. This review will provide a brief introduction to recent developments of the application IAP-siRNA in tumor studies, with the aim of inspiring future treatment of HCC.

RNAi-mediated knockdown of the c-jun gene sensitizes radioresistant human nasopharyngeal carcinoma cell line CNE-2R to radiation

This study aimed to investigate the effect of RNA interference (RNAi)-mediated downregulation of the expression of the c-jun gene (a proto-oncogene) on the radiosensitivity of a radioresistant human nasopharyngeal carcinoma cell line (CNE-2R) and to validate its potential as an anticancer target. A lentiviral vector with c-jun small hairpin RNA (shRNA) was constructed and transfected into CNE-2R cells. The gene silencing efficiency of these recombinants was confirmed by RT-PCR and western blotting. Radiosensitivity, cell proliferation, cell cycle profile and apoptosis were assessed using colony formation assay, CCK-8 assay and flow cytometry, respectively. The lentiviral shRNA efficiently knocked down the expression of c-jun at both the mRNA and protein levels (P<0.05). c-jun-downregulated CNE-2R cells exhibited significantly decreased cell proliferation and enhanced radiosensitivity compared to the control group (P<0.05), and the effects were likely due to G2/M phase arrest and enhanced cell apoptosis. These data provide evidence that c-jun may be involved in the radioresistance of nasopharyngeal carcinoma (NPC) and knockdown of the c-jun gene may be a potential strategy to enhance the radiation sensitivity of NPC.

Suppression of VEGF by reversible-PEGylated histidylated polylysine in cancer therapy

A reversible-PEGylated polylysine is designed and developed for efficient delivery of siRNA. In this unique structure, the ε-amino groups of disulfide linked poly(ethylene glycol) (PEG) and polylysine (mPEG-SS-PLL) are partially replaced by histidine groups, in order to develop the histidylated reversible-PEGylated polylysine (mPEG-SS-PLH), for enhanced endosome escape ability. The transfection efficacy of mPEG-SS-PLH is found to closely correlate with histidine substitution. Its maximum transfection efficiencies are determined, respectively, to be 75%, 42%, and 24%, against 293T, MCF-7, and PC-3 cells. These data indicate that the transfection efficiencies can equal or even outweigh PEI-25k in the corresponding cells (80%, 38.5%, and 20%). The in vivo circulation and biodistribution of the polyplexes are monitored by fluorescent imaging. The in vivo gene transfection is carried out by intravenous injection of pEGFP to BALB/c mice using the xenograft models. The in vivo experimental results show effective inhibition of tumor growth by mPEG-SS-PLH/siRNA-VEGF, indicating its high potential for clinical applications.

Co-delivery of doxorubicin and RNA using pH-sensitive poly (β-amino ester) nanoparticles for reversal of multidrug resistance of breast cancer

An appropriate co-delivery system for chemotherapeutic agents and nucleic acid drugs will provide a more efficacious approach for the treatment of breast cancer by reversing multidrug resistance (MDR). In this work, a new amphiphilic poly (β-amino ester), poly[(1,4-butanediol)-diacrylate-β-5-polyethylenimine]-block-poly[(1,4-butanediol)-diacrylate-β-5-hydroxy amylamine] (PDP-PDHA) was synthesized, and the doxorubicin (DOX) and survivin-targeting shRNA (shSur) co-loading nanoparticle (PDNs) were prepared. The pH-sensitive poly[(1,4-butanediol) diacrylate-β-5-hydroxy amylamine] (PDHA) endowed PDNs both pH-triggered drug release characteristics and enhanced endo/lysosomal escape ability, thus improving the cytotoxicity of DOX and the transfection efficiency. PDNs also increased the DOX accumulation, down-regulated 57.7% survivin expression, induced 80.8% cell apoptosis and changed the cell cycle in MCF-7/ADR cells. In the MCF-7/ADR tumor-bearing mice models, after administrated intravenously, PDNs raised the accumulation of DOX and shSur in the tumor tissue by 10.4 and 20.2 folds, respectively, resulting in obvious inhibition of the tumor growth with tumor inhibiting rate of 95.9%. The combination of DOX and RNA interference showed synergistic effect on overcoming MDR. Therefore, PDNs could be a promising co-delivery vector for effective therapy of drug resistant breast cancer.