Mechanisms of immune system activation in mammalians by small interfering RNA (siRNA)

siRNA-based Therapeutics in Hormone-driven Cancers: Advancements and benefits over conventional treatments

Hormone-related cancers, also known as hormone-sensitive or hormone-dependent cancers, rely on hormones such as estrogen, testosterone, and progesterone for growth. These malignancies, including breast, pituitary, thyroid, ovarian, uterine, cervical, and prostate cancers, often exhibit accelerated progression in response to hormonal signaling. Small interfering RNA (siRNA) has emerged as a groundbreaking gene suppression therapy since the FDA approval of its first product in 2018. With over 200 ongoing clinical trials, siRNA is being actively explored as a targeted treatment for hormone-related cancers. Its ability to silence specific oncogenes offers significant advantages over conventional therapies, which are often associated with toxicity, resistance, and non-specific targeting. However, challenges in siRNA delivery remain a major barrier to its clinical translation, limiting its ability to reach target cells effectively. This review evaluates the potential of siRNA in hormone-related cancers, addressing the shortcomings of traditional treatments while examining novel strategies to enhance siRNA delivery and overcome tumor microenvironment obstacles. Notably, no existing literature comprehensively consolidates siRNA-based therapies for these cancers, emphasizing the importance of this manuscript in bridging current knowledge gaps and advancing the translational application of siRNA therapeutics.

Antibody/siRNA Nanocarriers Against Wnt Signaling Suppress Oncogenic and Stem-Like Behavior in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is infamous for its aggressive phenotype and poorer prognosis when compared to other breast cancer subtypes. One factor contributing to this poor prognosis is that TNBC lacks expression of the receptors that available hormonal or molecular-oriented therapies attack. New treatments that exploit biological targets specific to TNBC are desperately needed to improve patient outcomes. One promising target for therapeutic manipulation is the Wnt signaling pathway, which has been associated with many invasive breast cancers, including TNBC. This pathway is activated in TNBC cells when extracellular Wnt ligands bind to overexpressed Frizzled7 (FZD7) transmembrane receptors, leading to downstream activation of intracellular β-catenin proteins. To target and inhibit Wnt signaling in TNBC cells, polymer nanoparticles (NPs) modified with anti-FZD7 antibodies and β-catenin small interfering RNAs (siRNAs) were developed, and their impact on the oncogenic behavior of treated TNBC cells was investigated. When compared to control NPs, the Wnt-targeted NPs induced greater levels of Wnt oncogene suppression. This led to greater inhibition of oncogenic and stem-like properties, including cell proliferation, drug resistance, and spheroid formation capacity. This work demonstrates a promising approach for targeting the Wnt pathway in TNBC to counter the cellular phenotypes that drive disease progression.

siRNA-based therapy for overcoming drug resistance in human solid tumours; molecular and immunological approaches

RNA interference (RNAi) is a primordial biological process that protects against external intrusion. SiRNA has the potential to selectively silence disease-related genes in a sequence-specific way, thus offering a promising therapeutic approach. The efficacy of siRNA-based therapies in cancer treatment has gained significant recognition due to multiple studies demonstrating its ability to effectively suppress cancer cells' growth and multiplication. Moreover, siRNA-based medicines have shown considerable promise in enhancing the sensitivity of cancer cells to chemotherapy and other treatment methods by suppressing genes that play a role in the development of drug resistance. Exploring and identifying functional genes linked to cancer cell characteristics and drug resistance is crucial for developing effective siRNAs for cancer treatment and advancing targeted and personalized therapeutics. Targeting and silencing genes in charge of resistance mechanisms, such as those involved in drug efflux, cell survival, or DNA repair, is possible with siRNA therapy in the context of drug resistance, especially cancer. Through inhibiting these genes, siRNA therapy can prevent resistance and restore the efficacy of traditional medications. This review addresses the potential of siRNAs in addressing drug resistance in human tumours, opening up new possibilities in cancer therapy. This review article offers a non-systematic summary of how different siRNA types contribute to cancer cells' treatment resistance. Using pertinent keywords, sources were chosen from reliable databases, including PubMed, Scopus, and Google Scholar. The review covered essential papers in this area and those that mainly addressed the function of siRNA in drug resistance. The articles examined in connection with the title of this review were primarily published from 2020 onward and are based on in vitro studies. Furthermore, this article examines the potential barriers and prospective perspectives of siRNA therapies.

Specific small interfering RNAs (siRNAs) for targeting the metastasis, immune responses, and drug resistance of colorectal cancer cells (CRC)

Colorectal cancer (CRC) involves various genetic alterations, with liver metastasis posing a significant clinical challenge. Furthermore, CRC cells mostly show an increase in resistance to traditional treatments like chemotherapy. It is essential to investigate more advanced and effective therapies to prevent medication resistance and metastases and extend patient life. As a result, it is anticipated that small interfering RNAs (siRNAs) would be exceptional instruments that can control gene expression by RNA interference (RNAi). In eukaryotes, RNAi is a biological mechanism that destroys specific messenger RNA (mRNA) molecules, thereby inhibiting gene expression. In the management of CRC, this method of treatment represents a potential therapeutic agent. However, it is important to acknowledge that siRNA therapies have significant issues, such as low serum stability and nonspecific absorption into biological systems. Delivery mechanisms are thus being created to address these issues. In the current work, we address the potential benefits of siRNA therapy and outline the difficulties in treating CRCby focusing on the primary signaling pathways linked to metastasis as well as genes implicated in the multi-drug resistance (MDR) process.

Therapeutic efficacy of a novel self-assembled immunostimulatory siRNA combining apoptosis promotion with RIG-I activation in gliomas

BACKGROUND

Current cancer therapies often fall short in addressing the complexities of malignancies, underscoring the urgent need for innovative treatment strategies. RNA interference technology, which specifically suppresses gene expression, offers a promising new approach in the fight against tumors. Recent studies have identified a novel immunostimulatory small-interfering RNA (siRNA) with a unique sequence (sense strand, 5'-C; antisense strand, 3'-GGG) capable of activating the RIG-I/IRF3 signaling pathway. This activation induces the release of type I and III interferons, leading to an effective antiviral immune response. However, this class of immunostimulatory siRNA has not yet been explored in cancer therapy.

METHODS

IsiBCL-2, an innovative immunostimulatory siRNA designed to suppress the levels of B-cell lymphoma 2 (BCL-2), contains a distinctive motif (sense strand, 5'-C; antisense strand, 3'-GGG). Glioblastoma cells were subjected to 100 nM isiBCL-2 treatment in vitro for 48 h. Morphological changes, cell viability (CCK-8 assay), proliferation (colony formation assay), migration/invasion (scratch test and Transwell assay), apoptosis rate, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) were evaluated. Western blotting and immunofluorescence analyses were performed to assess RIG-I and MHC-I molecule levels, and ELISA was utilized to measure the levels of cytokines (IFN-β and CXCL10). In vivo heterogeneous tumor models were established, and the anti-tumor effect of isiBCL-2 was confirmed through intratumoral injection.

RESULTS

IsiBCL-2 exhibited significant inhibitory effects on glioblastoma cell growth and induced apoptosis. BCL-2 mRNA levels were significantly decreased by 67.52%. IsiBCL-2 treatment resulted in an apoptotic rate of approximately 51.96%, accompanied by a 71.76% reduction in MMP and a 41.87% increase in ROS accumulation. Western blotting and immunofluorescence analyses demonstrated increased levels of RIG-I, MAVS, and MHC-I following isiBCL-2 treatment. ELISA tests indicated a significant increase in IFN-β and CXCL10 levels. In vivo studies using nude mice confirmed that isiBCL-2 effectively impeded the growth and progression of glioblastoma tumors.

CONCLUSIONS

This study introduces an innovative method to induce innate signaling by incorporating an immunostimulatory sequence (sense strand, 5'-C; antisense strand, 3'-GGG) into siRNA, resulting in the formation of RNA dimers through Hoogsteen base-pairing. This activation triggers the RIG-I signaling pathway in tumor cells, causing further damage and inducing a potent immune response. This inventive design and application of immunostimulatory siRNA offer a novel perspective on tumor immunotherapy, holding significant implications for the field.

FZD7-Targeted Nanoparticles to Enhance Doxorubicin Treatment of Triple-Negative Breast Cancer

Doxorubicin (DOX) is a chemotherapy agent commonly used to treat triple-negative breast cancer (TNBC), but it has insufficient efficacy against the disease and considerable toxicity due to its off-target delivery. To improve the specificity of DOX for TNBC, we encapsulated it in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) coated with antibodies against Frizzled7 (FZD7), a receptor that is overexpressed on TNBC cells and which is a key activator of the Wnt signaling pathway. In vitro studies show that DOX encapsulation does not hinder its ability to localize to the nucleus in human TNBC cell cultures and that DOX delivered via NPs induces apoptosis and DNA damage via H2A.X phosphorylation to the same degree as freely delivered DOX. FZD7-targeted NPs delivering DOX caused significantly greater inhibition of metabolic activity and led to a smaller cell population following treatment when compared to freely delivered DOX or DOX-loaded NPs coated only with poly(ethylene glycol) (PEG). The FZD7 antibodies additionally provided significant levels of Wnt pathway inhibition, as demonstrated by an increase in β-catenin phosphorylation, indicative of β-catenin destruction and downregulation. These results show that FZD7-targeted platforms have great promise for improving the therapeutic window of otherwise toxic chemotherapies like DOX in TNBC and other cancers that display the overexpression of FZD7 receptors.

Small interfering RNA (siRNA)-based therapeutic applications against viruses: principles, potential, and challenges

RNA has emerged as a revolutionary and important tool in the battle against emerging infectious diseases, with roles extending beyond its applications in vaccines, in which it is used in the response to the COVID-19 pandemic. Since their development in the 1990s, RNA interference (RNAi) therapeutics have demonstrated potential in reducing the expression of disease-associated genes. Nucleic acid-based therapeutics, including RNAi therapies, that degrade viral genomes and rapidly adapt to viral mutations, have emerged as alternative treatments. RNAi is a robust technique frequently employed to selectively suppress gene expression in a sequence-specific manner. The swift adaptability of nucleic acid-based therapeutics such as RNAi therapies endows them with a significant advantage over other antiviral medications. For example, small interfering RNAs (siRNAs) are produced on the basis of sequence complementarity to target and degrade viral RNA, a novel approach to combat viral infections. The precision of siRNAs in targeting and degrading viral RNA has led to the development of siRNA-based treatments for diverse diseases. However, despite the promising therapeutic benefits of siRNAs, several problems, including impaired long-term protein expression, siRNA instability, off-target effects, immunological responses, and drug resistance, have been considerable obstacles to the use of siRNA-based antiviral therapies. This review provides an encompassing summary of the siRNA-based therapeutic approaches against viruses while also addressing the obstacles that need to be overcome for their effective application. Furthermore, we present potential solutions to mitigate major challenges.

Combination therapy with chitosan/siRNA nanoplexes targeting PDGF-D and PDGFR-β reveals anticancer effect in breast cancer

BACKGROUND

Platelet derived growth factors (PDGF)-D and the expression of its receptor increase in neoplastic progression of cancer. Co-silencing of growth factor and receptor can be suggested as an important strategy for effective cancer therapy. In the present study, we hypothesized that suppression of PDGF-D signaling pathway with small interfering RNAs (siRNAs) targeting both PDGF-D and PDGF receptor (PDGFR)-β is a promising strategy for anticancer therapy.

METHODS

Chitosan nanoplexes containing dual and single siRNA were prepared at different weight ratios and controlled by gel retardation assay. Characterization, cellular uptake, gene silencing and invasion studies were performed. The effect of nanoplexes on breast tumor growth, PDGF expression and apoptosis was investigated.

RESULTS

We have shown that downregulation of PDGF-D and PDGFR-β with chitosan/siRNA nanoplex formulations reduced proliferation and invasion in breast cancer cells. In the in vivo breast tumor model, it was determined that the intratumoral administration of chitosan/siPDGF-D/siPDGFR-β nanoplexes markedly decreased the tumor volume and PDGF-D and PDGFR-β mRNA and protein expression levels and increased apoptosis.

CONCLUSIONS

According to the results obtained, we evaluated the effect of PDGF-D and PDGFR-β on breast tumor development and showed that RNAi-mediated inhibition of this pathway formulated with chitosan nanoplexes can be considered as a new breast cancer therapy strategy.

A β-Cyclodextrin-Based Nanoparticle with Very High Transfection Efficiency Unveils siRNA-Activated TLR3 Responses in Human Prostate Cancer Cells

Synthetic double-stranded small interfering RNAs (siRNAs) mimic interference RNAs (RNAi) and can bind target mRNAs with a high degree of specificity, leading to selective knockdown of the proteins they encode. However, siRNAs are very labile and must be both protected and transported by nanoparticles to be efficiently delivered into cells. In this work, we used a Janus-type polycationic amphiphilic β-cyclodextrin derivative to efficiently transfect siRNAs targeting mRNAs encoding mitogen-activated protein kinase (p42-MAPK) or Ras homolog enriched in brain (Rheb) into different cancer cell lines as well as astrocytes. We took advantage of this high transfection efficiency to simultaneously knock down p42-MAPK and Rheb to boost docetaxel (DTX)-mediated toxicity in two human prostate cancer cell lines (LNCaP and PC3). We found that double knockdown of p42-MAPK and Rheb increased DTX-toxicity in LNCaP but not in PC3 cells. However, we also observed the same effect when scramble siRNA was used, therefore pointing to an off-target effect. Indeed, we found that the siRNA we used in this work induced toll-like receptor 3 activation, leading to β-interferon production and caspase activation. We believe that this mechanism could be very useful as a general strategy to elicit an immune response against prostate cancer cells.

Aptamer-siRNA chimeras: Promising tools for targeting HER2 signaling in cancer

RNA interference is a transformative approach and has great potential in the development of novel and more efficient cancer therapeutics. Immense prospects exist in the silencing of HER2 and its downstream genes which are overexpressed in many cancers, through exogenously delivered siRNA. However, there is still a long way to exploit the full potential and versatility of siRNA therapeutics due to the challenges associated with the stability and delivery of siRNA targeted to specific sites. Aptamers offer several advantages as a vehicle for siRNA delivery, over other carriers such as antibodies. In this review, we discuss the progress made in the development and applications of aptamer-siRNA chimeras in HER2 targeting and gene silencing. A schematic workflow is also provided which will provide ample insight for all those researchers who are new to this field. Also, we think that a mechanistic understanding of the HER2 signaling pathway is crucial in designing extensive investigations aimed at the silencing of a wider array of genes. This review is expected to stimulate more research on aptamer-siRNA chimeras targeted against HER2 which might arm us with potential effective therapeutic interventions for the management of cancer.

The Role of Liquid Biopsy Analytes in Diagnosis, Treatment and Prognosis of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignant tumors of the digestive tract worldwide and is a serious threat to human life and health. CRC occurs and develops in a multi-step, multi-stage, and multi-gene process, in which abnormal gene expression plays an important role. CRC is currently diagnosed via endoscopy combined with tissue biopsy. Compared with tissue biopsy, liquid biopsy technology has received increasingly more attention and applications in the field of molecular detection due to its non-invasive, safe, comprehensive, and real-time dynamic nature. This review article discusses the application and limitations of current liquid biopsy analytes in the diagnosis, treatment, and prognosis of CRC, as well as directions for their future development.

Biotechnological Evolution of siRNA Molecules: From Bench Tool to the Refined Drug

The depth and versatility of siRNA technologies enable their use in disease targets that are undruggable by small molecules or that seek to achieve a refined turn-off of the genes for any therapeutic area. Major extracellular barriers are enzymatic degradation of siRNAs by serum endonucleases and RNAases, renal clearance of the siRNA delivery system, the impermeability of biological membranes for siRNA, activation of the immune system, plasma protein sequestration, and capillary endothelium crossing. To overcome the intrinsic difficulties of the use of siRNA molecules, therapeutic applications require nanometric delivery carriers aiming to protect double-strands and deliver molecules to target cells. This review discusses the history of siRNAs, siRNA design, and delivery strategies, with a focus on progress made regarding siRNA molecules in clinical trials and how siRNA has become a valuable asset for biopharmaceutical companies.

Retinoic Acid-Inducible Gene I-Mediated Innate Immune Stimulation by Chemically Synthesized Long Double-Stranded RNAs Is Structure and Sequence Dependent

Double-stranded RNAs (dsRNAs) longer than 30 bp have not been considered desirable RNA interference (RNAi) triggering structures in mammalian cells as they nonspecifically activate innate immune response. However, in earlier studies, not only dsRNA length but also 5'-triphosphate moiety produced by in vitro transcription might have affected the stimulation of innate immune system. Herein, using chemically synthesized long dsRNAs without 5'-triphosphate, we elucidated direct relationship between length of dsRNAs and innate immune stimulation. First, we found that blunt-ended, chemically synthesized 38/40-60 bp-long dsRNAs induced retinoic acid-inducible gene I (RIG-I)-mediated innate immune response, which was suppressed by the introduction of the 2-nt 3' overhang structure. Surprisingly, we discovered that RIG-I activation by these long dsRNAs is also sequence dependent, and the sequence composition at dsRNA termini is important for RIG-I activation. In addition, we identified that long dsRNAs over 38 bp could elicit single- or dual-target gene silencing in a Dicer-independent manner. Taken together, our findings may serve as guidelines to develop an immunostimulatory RNAi trigger to exploit host's innate immune system, as well as a specific dual-gene targeting RNAi therapeutics platform without nonspecific innate immune stimulation by RIG-I.

SAMiRNA Targeting Amphiregulin Alleviate Total-Body-Irradiation-Induced Renal Fibrosis

Fibrosis is a serious unintended side effect of radiation therapy. In this study, we aimed to investigate whether amphiregulin (AREG) plays a critical role in fibrosis development after total-body irradiation (TBI). We found that the expression of AREG and fibrotic markers, such as α-smooth muscle actin (α-SMA) and collagen type I alpha 1 (COL1α1), was elevated in the kidneys of 6 Gy TBI mice. Expression of AREG and α-SMA was mainly elevated in the proximal and distal tubules of the kidney in response to TBI, which was confirmed by immunofluorescence staining. Knockdown of Areg mRNA using self-assembled-micelle inhibitory RNA (SAMiRNA) significantly reduced the expression of fibrotic markers, including α-SMA and COL1α1, and inflammatory regulators. Finally, intravenous injections of SAMiRNA targeting mouse Areg mRNA (SAMiRNA-mAREG) diminished radiation-induced collagen accumulation in the renal cortex and medulla. Taken together, the results of the present study suggest that blocking of AREG signaling via SAMiRNA-mAREG treatment could be a promising therapeutic approach to alleviate radiation-induced kidney fibrosis.

Activation of Innate Immunity by Therapeutic Nucleic Acids

Nucleic acid-based therapeutics have gained increased attention during recent decades because of their wide range of application prospects. Immunostimulatory nucleic acids represent a promising class of potential drugs for the treatment of tumoral and viral diseases due to their low toxicity and stimulation of the body’s own innate immunity by acting on the natural mechanisms of its activation. The repertoire of nucleic acids that directly interact with the components of the immune system is expanding with the improvement of both analytical methods and methods for the synthesis of nucleic acids and their derivatives. Despite the obvious progress in this area, the problem of delivering therapeutic acids to target cells as well as the unresolved issue of achieving a specific therapeutic effect based on activating the mechanism of interferon and anti-inflammatory cytokine synthesis. Minimizing the undesirable effects of excessive secretion of inflammatory cytokines remains an unsolved task. This review examines recent data on the types of immunostimulatory nucleic acids, the receptors interacting with them, and the mechanisms of immunity activation under the action of these molecules. Finally, data on immunostimulatory nucleic acids in ongoing and completed clinical trials will be summarized.

Strategies for controlling the innate immune activity of conventional and self-amplifying mRNA therapeutics: Getting the message across

The recent approval of messenger RNA (mRNA)-based vaccines to combat the SARS-CoV-2 pandemic highlights the potential of both conventional mRNA and self-amplifying mRNA (saRNA) as a flexible immunotherapy platform to treat infectious diseases. Besides the antigen it encodes, mRNA itself has an immune-stimulating activity that can contribute to vaccine efficacy. This self-adjuvant effect, however, will interfere with mRNA translation and may influence the desired therapeutic outcome. To further exploit its potential as a versatile therapeutic platform, it will be crucial to control mRNA's innate immune-stimulating properties. In this regard, we describe the mechanisms behind the innate immune recognition of mRNA and provide an extensive overview of strategies to control its innate immune-stimulating activity. These strategies range from modifications to the mRNA backbone itself, optimization of production and purification processes to the combination with innate immune inhibitors. Furthermore, we discuss the delicate balance of the self-adjuvant effect in mRNA vaccination strategies, which can be both beneficial and detrimental to the therapeutic outcome.

Histone Deacetylase 7 Inhibition in a Murine Model of Gram-Negative Pneumonia-Induced Acute Lung Injury

BACKGROUND

Pulmonary infections remain the most common cause of Acute Respiratory Distress Syndrome (ARDS), a pulmonary inflammatory disease with high mortality, for which no targeted therapy currently exists. We have previously demonstrated an ameliorated syndrome with early, broad spectrum Histone Deacetylase (HDAC) inhibition in a murine model of gram-negative pneumonia-induced Acute Lung Injury (ALI), the underlying pulmonary pathologic phenotype leading to ARDS. With the current project we aim to determine if selective inhibition of a specific HDAC leads to a similar pro-survival phenotype, potentially pointing to a future therapeutic target.

METHODS

C57Bl/6 mice underwent endotracheal instillation of 30×10Escherichia coli (strain 19138) versus saline (n = 24). Half the infected mice were administered Trichostatin A (TSA) 30 min later. All animals were sacrificed 6 h later for tissue sampling and HDAC quantification, while another set of animals (n = 24) was followed to determine survival. Experiments were repeated with selective siRNA inhibition of the HDAC demonstrating the greatest inhibition versus scrambled siRNA (n = 24).

RESULTS

TSA significantly ameliorated the inflammatory phenotype and improved survival in infected-ALI mice, and HDAC7 was the HDAC with the greatest transcription and protein translation suppression. Similar results were obtained with selective HDAC7 siRNA inhibition compared with scrambled siRNA.

CONCLUSION

HDAC7 appears to play a key role in the inflammatory response that leads to ALI after gram-negative pneumonia in mice.

In vivo silencing of amphiregulin by a novel effective Self-Assembled-Micelle inhibitory RNA ameliorates renal fibrosis via inhibition of EGFR signals

Amphiregulin (AREG) is a transmembrane glycoprotein recently implicated in kidney fibrosis. Previously, we reported that the AREG-targeting Self-Assembled-Micelle inhibitory RNA (SAMiRNA-AREG) alleviated fibrosis by stably silencing the AREG gene, and reduced the side effects of conventional siRNA treatment of pulmonary fibrosis. However, the therapeutic effect of SAMiRNA-AREG in renal fibrosis has not been studied until now. We used two animal models of renal fibrosis generated by a unilateral ureteral obstruction (UUO) and an adenine diet (AD) to investigate whether SAMiRNA-AREG inhibited renal fibrosis. To investigate the delivery of SAMiRNA-AREG to the kidney, Cy5-labeled SAMiRNA-AREG was injected into UUO- and AD-induced renal fibrosis models. In both kidney disease models, SAMiRNA-AREG was delivered primarily to the damaged kidney. We also confirmed the protective effect of SAMiRNA-AREG in renal fibrosis models. SAMiRNA-AREG markedly decreased the UUO- and AD-induced AREG mRNA expression. Furthermore, the mRNA expression of fibrosis markers, including α-smooth muscle actin, fibronectin, α1(I) collagen, and α1(III) collagen in the UUO and AD-induced kidneys, was diminished in the SAMiRNA-AREG-treated mice. The transcription of inflammatory markers (tumor necrosis factor-α and monocyte chemoattractant protein-1) and adhesion markers (vascular cell adhesion molecule 1 and intercellular adhesion molecule 1) was attenuated. The hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining results showed that SAMiRNA-AREG decreased renal fibrosis, AREG expression, and epidermal growth factor receptor (EGFR) phosphorylation in the UUO- and AD-induced models. Moreover, we studied the effects of SAMiRNA-AREG in response to TGF-β1 in mouse and human proximal tubule cells, and mouse fibroblasts. TGF-β1-induced extracellular matrix production and myofibroblast differentiation were attenuated by SAMiRNA-AREG. Finally, we confirmed that upregulated AREG in the UUO or AD models was mainly localized in the distal tubules. In conclusion, SAMiRNA-AREG represents a novel siRNA therapeutic for renal fibrosis by suppressing EGFR signals.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

Molecular Mechanism of the Antiproliferative Activity of Short Immunostimulating dsRNA

Small double-stranded RNAs with certain sequence motifs are able to interact with pattern-recognition receptors and activate the innate immune system. Recently, we identified a set of short double-stranded 19-bp RNA molecules with 3-nucleotide 3′-overhangs that exhibited pronounced antiproliferative activity against cancer cells in vitro, and antitumor and antimetastatic activities in mouse models in vivo. The main objectives of this study were to identify the pattern recognition receptors that mediate the antiproliferative action of immunostimulating RNA (isRNA). Two cell lines, epidermoid carcinoma KB-3-1 cells and lung cancer A549 cells, were used in the study. These lines respond to the action of isRNA by a decrease in the growth rate, and in the case of A549 cells, also by a secretion of IL-6. Two sets of cell lines with selectively silenced genes encoding potential sensors and signal transducers of isRNA action were obtained on the basis of KB-3-1 and A549 cells. It was found that the selective silencing of PKR and RIG-I genes blocked the antiproliferative effect of isRNA, both in KB-3-1 and A549 cells, whereas the expression of MDA5 and IRF3 was not required for the antiproliferative action of isRNA. It was shown that, along with PKR and RIG-I genes, the expression of IRF3 also plays a role in isRNA mediated IL-6 synthesis in A549 cells. Thus, PKR and RIG-I sensors play a major role in the anti-proliferative signaling triggered by isRNA.

The double edge of anti-CD40 siRNA therapy: It increases renal microcapillar density but favours the generation of an inflammatory milieu in the kidneys of ApoE -/- mice

Background

Chronic kidney disease (CKD) is associated with endothelial dysfunctions thus prompting links between microcirculation (MC), inflammation and major cardiovascular risk factors.

Purpose of the study

We have previously reported that siRNA-silencing of CD40 (siCD40) reduced atherosclerosis (ATH) progression. Here, we have deepened on the effects of the siCD40 treatment by evaluating retrospectively, in stored kidneys from the siCD40 treated ApoE^−/− mice, the renal microcirculation (measured as the density of peritubular capillaries), macrophage infiltration and NF-κB activation.

Methods

Kidneys were isolated after 16 weeks of treatment with the anti-CD40 siRNA (siCD40), with a scrambled control siRNA (siSC) or with PBS (Veh. group). Renal endothelium, infiltrating macrophages and activated NF-κB in endothelium were identified by immunohistochemistry, while the density of stained peritubular capillaries was quantified by image analysis.

Results

ATH was associated with a reduction in renal MC, an effect reversed by the anti-CD40 siRNA treatment (3.8 ± 2.7% in siCD40; vs. 1.8 ± 0.1% in siSC; or 1.9 ± 1.6% in Veh.; p < 0.0001). Furthermore, siCD40 treatment reduced the number of infiltrating macrophages compared to the SC group (14.1 ± 5.9 cells/field in siCD40; vs. 37.1 ± 17.8 cells/field in siSC; and 1.3 ± 1.7 cells/field in Veh.; p = 0.001). NF-κB activation also peaked in the siSC group, showing lower levels in the siCD40 and Veh. groups (63 ± 60 positive cells/section in siCD40; vs. 152 ± 44 positive cells/section in siSC; or 26 ± 29 positive cells/section in veh.; p = 0.014). Lastly, serum creatinine was also increased in the siCD40 (3.4 ± 3.3 mg/dL) and siSC (4.6 ± 3.0 mg/dL) groups when compared with Veh. (1.1 ± 0.9 mg/dL, p = 0.1).

Conclusions

Anti-CD40 siRNA therapy significantly increased the density of peritubular capillaries and decreased renal inflammation in the ATH model. These data provide a physiological basis for the development of renal diseases in patients with ATH. Furthermore, our results also highligth renal off-target effects of the siRNA treatment which are discussed.

Graphical abstract

Current Development of siRNA Bioconjugates: From Research to the Clinic

Small interfering RNAs (siRNAs) acting via RNA interference mechanisms are able to recognize a homologous mRNA sequence in the cell and induce its degradation. The main problems in the development of siRNA-based drugs for therapeutic use are the low efficiency of siRNA delivery to target cells and the degradation of siRNAs by nucleases in biological fluids. Various approaches have been proposed to solve the problem of siRNA delivery in vivo (e.g., viruses, cationic lipids, polymers, nanoparticles), but all have limitations for therapeutic use. One of the most promising approaches to solve the problem of siRNA delivery to target cells is bioconjugation; i.e., the covalent connection of siRNAs with biogenic molecules (lipophilic molecules, antibodies, aptamers, ligands, peptides, or polymers). Bioconjugates are "ideal nanoparticles" since they do not need a positive charge to form complexes, are less toxic, and are less effectively recognized by components of the immune system because of their small size. This review is focused on strategies and principles for constructing siRNA bioconjugates for in vivo use.

Small interfering RNA-mediated gene suppression as a therapeutic intervention in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and difficult-to-cure cancers worldwide. Owing to the late diagnosis and drug resistance of malignant hepatocytes, treatment of this cancer by conventional chemotherapy agents is challenging, and researchers are seeking new alternative treatment options to overcome therapy resistance in this neoplasm. RNA interference (RNAi) is a potent and specific approach in targeting gene expression and has emerged as a novel therapeutic tool for many diseases, including cancers. Small interfering RNA (siRNA) is a type of RNAi that is produced intracellularly from exogenous synthetic oligonucleotides and can selectively knock down target gene expression in a sequence-specific manner. Various factors play roles in the initiation and progression of HCC and provide multiple candidate targets for siRNA intervention. In addition, due to the liver's unique architecture and availability of some hepatic siRNA delivery methods, this organ has received much more attention as a target tissue for such oligonucleotide action. Recent advances in designing nanoparticle systems for the in vivo delivery of siRNAs have markedly enhanced the potency of siRNA-mediated gene silencing under clinical development for HCC therapy. The utility of siRNAs as anti-HCC agents is the subject of the current review. siRNA-based gene therapies could be one of the main feasible approaches for HCC therapy in the future.

Litopenaeus vannamei notch affects lipopolysaccharides induced reactive oxygen species

Notch signaling pathway was originally discovered in the development stage of drosophila but has recently been found to play essential roles in innate immunity. Most previous studies on Notch have focused on mammals, whereas, in this study, we employed the shrimp Litopenaeus vannamei as a model to study the functions of Notch in invertebrate innate immune system. Our results showed that LvNotch was highly expressed in hemocytes and could be strongly induced by lipopolysaccharides (LPS) injection. Small interfering RNA (siRNA)-mediated knockdown of LvNotch could significantly increase LPS induced L. vannamei mortality, which might be due to the fact that LPS induced ROS was greatly enhanced in LvNotch knockdown shrimps. Further, quantitative polymerase chain reaction (qPCR) analysis revealed that LvNotch could affect the expression of multiple genes, including dorsal, relish, anti-lipopolysaccharide factor 1 (ALF1), ALF3 and NADH dehydrogenases which were upregulated, and Hypoxia-inducible factor (HIF, α/β) which were downregulated in LPS treated shrimps. In summary, LvNotch is important in the control of inflammation-induced ROS production in shrimp.

Enhancement of chemosensitivity by simultaneously silencing of Mcl-1 and Survivin genes using small interfering RNA in human myelomonocytic leukaemia

Acute myeloid leukaemia (AML) is a genetically heterogeneous, severe and rapidly progressing disease triggered by blocking granulocyte or monocyte differentiation and maturation. Overexpression of myeloid cell leukaemia-1 (Mcl-1) and Survivin is associated with drug resistance, tumour progression and inhibition of apoptotic mechanisms in leukaemia and several cancers. In the present study, we examined the combined effect of etoposide and dual siRNA-mediated silencing of Mcl-1 and Survivin on U-937 AML cells. The AML cells were co-transfected with Mcl-1 and Survivin-specific siRNAs and genes silencing were confirmed by quantitative real-time PCR and Western blotting. Subsequently, MTT assay was used for the evaluation of cytotoxic effects by dual siRNA and etoposide on their own and in combination. For the studying of apoptosis, DNA-histone ELISA and annexin-V/FITC assays were performed. Co-transfection of Mcl-1 and Survivin siRNA significantly blocked their expression at the mRNA and protein levels, leading to the induction of apoptosis and strong inhibition of growth (p < .05). Besides, combined treatment of etoposide with Mcl-1 and Survivin siRNAs co-transfection leads to synergistically enhance etoposide-induced cytotoxic and apoptotic effects (p < .05). The results showed that Mcl-1 and Survivin play a major role in the U937 cells survival and their resistance relative to etoposide. Thus, Mcl-1 and Survivin can be considered as promising molecular targets for the treatment of AML. The combination treatment with etoposide, and siRNA-mediated silencing of corresponding genes may be a novel strategy in chemoresistance AML treatment.

Silencing of High Mobility Group Isoform I-C (HMGI-C) Enhances Paclitaxel Chemosensitivity in Breast Adenocarcinoma Cells (MDA-MB-468)

PURPOSE

HMGI-C (High Mobility Group protein Isoform I-C) protein is a member of the high-mobility group AT-hook (HMGA) family of small non-histone chromosomal protein that can modulate transcription of an ample number of genes. Genome-wide studies revealed up regulation of the HMGI-C gene in many human cancers. We suggested that HMGI-C might play a critical role in the progression and migration of various tumors. However, the exact role of HMGI-C in breast adenocarcinoma has not been cleared.

METHODS

The cells were transfected with siRNAs using transfection reagent. Relative HMGI-C mRNA and protein levels were measured by quantitative real-time PCR and Western blotting, respectively. The cytotoxic effects of HMGI-C siRNA, Paclitaxel alone and combination on breast adenocarcinoma cells were determined using MTT assay. The migration after treatment by HMGI-C siRNA, Paclitaxel alone and combination were detected by wound-healing respectively.

RESULTS

HMGI-C siRNA significantly reduced both mRNA and protein expression levels in a 48 hours after transfection and dose dependent manner. We observed that the knockdown of HMGI-C led to the significant reduced cell viability and inhibited cells migration in MDA-MB-468 cells in vitro.

CONCLUSION

These results propose that HMGI-C silencing and Paclitaxel treatment alone can inhibit the proliferation and migration significantly, furthermore, synergic effect of HMGI-C siRNA and Paclitaxel showed higher inhibition compared to mono treatment. Taken together, HMGI-C could be used as a promising therapeutic agent in the treatment of human breast adenocarcinoma. Therefore HMGI-C siRNA may be an effective adjuvant in human breast adenocarcinoma.

HMGI-C suppressing induces P53/caspase9 axis to regulate apoptosis in breast adenocarcinoma cells

PURPOSE

The HMGI-C (high mobility group protein isoform I-C) protein is a member of the high-mobility group AT-hook (HMGA) family of small non-histone chromosomal proteins that can modulate transcription of an ample number of genes. Genome-wide studies reveal upregulation of the HMGI-C gene in many human cancers, which suggests that HMGI-C might play a critical role in the progression of various tumors. However, the exact role of HMGI-C in breast adenocarcinoma has not been made clear.

METHODS

HMGI-C mRNA expression in breast cancer samples and marginal normal tissues was characterized using qRT-PCR. The cytotoxic effects of HMGI-C siRNA on breast adenocarcinoma cells were determined using MTT assay. Relative HMGI-C mRNA and protein levels were measured by quantitative real-time PCR and western blotting, respectively. Apoptosis detection was done using TUNEL and Annexin-V/PI assays, P53, caspase 3, 9, 8 and Bcl2 proteins evaluated by protein gel blot and miR34a, Let-7a genes investigates by QRT-PCR assay. Cell cycle was analyzed by flow cytometry assay using propidium iodide DNA staining.

RESULTS

An overexpression of HMGA2 was revealed with highly statistically significant differences between breast cancer samples and marginal normal tissues (P < 0.0001). HMGI-C siRNA significantly reduced both mRNA and protein expression levels in a 48-hour period after transfection and in a dose-dependent manner. We observed that the knockdown of HMGI-C led to the significant induction of apoptosis via mitochondrial pathway by inducing miR34a and cell cycle arrest in MDA-MB-468 cells in vitro.

CONCLUSIONS

These results propose that HMGI-C might play a critical role in the progression of breast adenocarcinoma. Here we introduced HMGI-C as a potential therapeutic target for trigger apoptosis and cell cycle arrest in human breast adenocarcinoma. Therefore HMGI-C siRNA may be an effective adjuvant in human breast adenocarcinoma.

BACH1, the master regulator gene: A novel candidate target for cancer therapy

BACH1 (BTB and CNC homology 1, basic leucine zipper transcription factor 1) is a transcriptional factor and a member of cap 'n' collar (CNC) and basic region leucine zipper factor family. In contrast to other bZIP family members, BACH1 appeared as a comparatively specific transcription factor. It acts as transcription regulator and is recognized as a recently hypoxia regulator and functions as an inducible repressor for the HO-1 gene in many human cell types in response to stress oxidative. In regard to studies lately, although, BACH1 has been related to the regulation of oxidative stress and heme oxidation, it has never been linked to invasion and metastasis. Recent studies have showed that BACH1 is involved in bone metastasis of breast cancer by up-regulating vital metastatic genes like CXCR4 and MMP1. This newly discovered aspect of BACH1 gene provides new insight into cancer progression study and stands on its master regulator role in metastasis process, raising the possibility of considering it as a potential target for cancer therapy.