Potential use of RNA interference in cancer therapy. Expert Rev Mol Med. 2010;12:e26. [PMID: 20716384 DOI: 10.1017/S1462399410001584]

Natural Products: Implication in Cancer Prevention and Treatment through Modulating Various Biological Activities

Cancer is one of the most leading causes of death worldwide. It is one of the primary global diseases that cause morbidity and mortality in millions of people. It is usually caused by different carcinogenic agents that damage the genetic material and alter the cell signaling pathways. Carcinogens are classified into two groups as genotoxic and non-genotoxic agents. Genotoxic carcinogens are capable of directly altering the genetic material, while the non-genotoxic carcinogens are capable of producing cancer by some secondary mechanisms not related to direct gene damage. There is undoubtedly the greatest need to utilize some novel natural products as anticancer agents, as these are within reach everywhere. Interventions by some natural products aimed at decreasing the levels and conditions of these risk factors can reduce the frequency of cancer incidences. Cancer is conventionally treated by surgery, radiation therapy and chemotherapy, but such treatments may be fast-acting and causes adverse effects on normal tissues. Alternative and innovative methods of cancer treatment with the least side effects and improved efficiency are being encouraged. In this review, we discuss the different risk factors of cancer development, conventional and innovative strategies of its management and provide a brief review of the most recognized natural products used as anticancer agents globally.

Chemical Protein Degradation Approach and its Application to Epigenetic Targets

In addition to traditional drugs, such as enzyme inhibitors, receptor agonists/antagonists, and protein-protein interaction inhibitors as well as genetic technology, such as RNA interference and the CRISPR/Cas9 system, protein knockdown approaches using proteolysis-targeting chimeras (PROTACs) have attracted much attention. PROTACs, which induce selective degradation of their target protein via the ubiquitin-proteasome system, are useful for the down-regulation of various proteins, including disease-related proteins and epigenetic proteins. Recent reports have shown that chemical protein knockdown is possible not only in cells, but also in vivo and this approach is expected to be used as the therapeutic strategy for several diseases. Thus, this approach may be a significant technique to complement traditional drugs and genetic ablation and will be more widely used for drug discovery and chemical biology studies in the future. In this personal account, a history of chemical protein knockdown is introduced, and its features, recent progress in the epigenetics field, and future outlooks are discussed.

Pancreatic cancer actionable genes in precision medicine and personalized surgery

Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer with an overall 5-year survival rate less than 5% due to the poor early diagnosis and lack of effective therapeutic options. The most effective therapy remains surgery, however post-operative survival could be enhanced with effective adjuvant therapy. The massive information gained from Omics techniques on PDAC at the beginning of the 21st century is a remarkable accomplishment. However, the information gained from the omics data, including next generation sequencing data, has yet to successfully affect care of patients suffering with PDAC. Therefore, we propose the development of an actionable genomic platform that matches a patient's PDAC clinically actionable genes with potential targeted adjuvant therapies. Using this platform, PDX1 has been identified as a potential actionable gene for PDAC, therefore, RNAi therapy, gene therapy and small inhibitory drugs, all targeting PDX1, serve as potential targeted adjuvant therapies. Preclinical studies support the hypothesis that identification of PDAC actionable genes could permit translation of a patient's genomic information into precision targeted adjuvant therapy for PDAC.

Lentivirus mediated RNA interference of EMMPRIN (CD147) gene inhibits the proliferation, matrigel invasion and tumor formation of breast cancer cells

BACKGROUND

Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN) or cluster of differentiation 147 (CD147), a glycoprotein enriched on the plasma membrane of tumor cells, promotes proliferation, invasion, metastasis, and survival of malignant tumor cells. In this study, we sought to examine the expression of EMMPRIN in breast tumors, and to identify the potential roles of EMMPRIN on breast cancer cells.

METHODS

EMMPRIN expression in breast cancer tissues was assessed by immunohistochemistry. We used a lentivirus vector-based RNA interference (RNAi) approach expressing short hairpin RNA (shRNA) to knockdown EMMPRIN gene in breast cancer cell lines MDA-MB-231 and MCF-7. In vitro, Cell proliferative, invasive potential were determined by Cell Counting Kit (CCK-8), cell cycle analysis and matrigel invasion assay, respectively. In vivo, tumorigenicity was monitored by inoculating tumor cells into breast fat pad of female nude mice.

RESULTS

EMMPRIN was over-expressed in breast tumors and breast cancer cell lines. Down-regulation of EMMPRIN by lentivirus vector-based RNAi led to decreased cell proliferative, decreased matrigel invasion in vitro, and attenuated tumor formation in vivo.

CONCLUSION

High expression of EMMPRIN plays a crucial role in breast cancer cell proliferation, matrigel invasion and tumor formation.

PDX1 associated therapy in translational medicine

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely poor prognosis and a low median survival due to lack of the early and reliable detection and effective therapeutic options, despite improvements observed for many other cancers in last decade. Pancreatic and duodenal homeobox 1 (PDX1), which is a homeodomain-containing transcription factor and a key regulator for insulin gene expression, β cell maturation and proper β cell function maintenance in the pancreas. Our previous studies revealed that PDX1 promotes tumorigenesis and it is a promising therapeutic target for PDAC. For translational purposes, we developed three therapeutic platforms utilizing RNA interference (RNAi), gene therapy and small inhibitory drug targeting PDX1, and further validated them in PDAC preclinical models both in vitro and in vivo. These PDX1 targeted therapies significantly inhibited PDX1 expression in PDAC cells, ablated PDX1-expressing human PDAC xenograft tumor growth, and prolonged survival in the PDAC mouse models. The data from these preclinical studies proved the translational potentials of PDX1 targeted therapies in PDAC and suggest that the strategy of developing PDX1 targeted therapies would permit a rapid bench-to-bedside translation of other relevant gene therapies, which would eventually benefit the patients suffering from this deadly disease.

Advances, nuances, and potential pitfalls when exploiting the therapeutic potential of RNA interference

The discovery of RNA interference (RNAi) holds the potential to alter the paradigm of medical therapeutics. With the ability to selectively silence the function of a gene, RNAi not only provides an indispensable research tool for determining the function of a gene, but also offers potential for the development of novel therapeutics that will inhibit specific genes involved in disease. New concepts in therapeutics have been uncovered through the study of RNAi. Nuances have emerged. For instance, global RNAi pathways can be affected by somatic mutations in cancer and cellular stress, such as hypoxia. Also, viral gene therapy can have unexpected effects on endogenous short noncoding RNA pathways. Therefore, it is important to understand where RNAi therapeutics enter the processing pathways. We highlight the evolving use of RNAi as a new class of therapeutics, such as for amyloidosis, and address some of the anticipated challenges associated with its clinical application.

Epigenetic therapies - a new direction in clinical medicine

A major biomedical advance from recent years was the finding that gene expression and phenotypic traits may be shaped by potentially reversible and heritable modifications that occur without altering the sequence of the nucleotides, and became known as epigenetic changes. The term 'epigenetics' dates back to the 1940s, when it was first used in context of cellular differentiation decisions that are made during development. Since then, our understanding of epigenetic modifications that govern development and disease expanded considerably. The contribution of epigenetic changes to shaping phenotypes brings at least two major clinically relevant benefits. One of these, stemming from the reversibility of epigenetic changes, involves the possibility to therapeutically revert epigenetic marks to re-establish prior gene expression patterns. The strength and the potential of this strategy are illustrated by the first four epigenetic drugs that were approved in recent years and by the additional candidates that are at various stages in preclinical studies and clinical trials. The second particularity is the finding that epigenetic changes precede the appearance of histopathological modifications. This has the potential to facilitate the emergence of epigenetic biomarkers, some of which already entered the clinical arena, catalysing a major shift in prophylactic and therapeutic strategies, and promising to fill a decades-old gap in preventive medicine.

Effectiveness of cationic liposome-mediated local delivery of myostatin-targeting small interfering RNA in vivo

This study evaluated the effectiveness of local administration of cationic liposome-delivered myostatin-targeting siRNA. Myostatin (Mst)-siRNA and scrambled (scr)-siRNA-lipoplexes were injected into the masseter muscles of wild type and dystrophin-deficient mdx mice, which model Duchenne muscular dystrophy. One week after injection, the masseter muscles were dissected for histometric analyses. To evaluate changes in masseter muscle activity, masseter electromyographic (EMG) measurements were performed. One week after local administration of Mst-siRNA-lipoplexes, masseter muscles and myofibrils were significantly larger compared to control masseter muscles treated with scr-siRNA-lipoplexes. Real-time polymerase chain reaction (PCR) analyses revealed significant upregulation of the myogenic regulatory factors MyoD and myogenin and significant downregulation of the adipogenic transcription factors peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein-α (CEBPα) in masseter muscles treated with Mst-siRNA-lipoplexes. The duty times of masseter muscle activity exceeding 5% showed a slight tendency to increase in both wild type and mdx mice. Therefore, cationic liposome-mediated local administration of Mst-siRNA could increase muscular size and improve muscle activity. Since cationic liposomes delivered siRNA to muscles effectively and are safe and cost-effective, they may represent a therapeutic tool for use in treating muscular diseases.

Targeting fungal genes by diced siRNAs: a rapid tool to decipher gene function in Aspergillus nidulans

Background

Gene silencing triggered by chemically synthesized small interfering RNAs (siRNAs) has become a powerful tool for deciphering gene function in many eukaryotes. However, prediction and validation of a single siRNA duplex specific to a target gene is often ineffective. RNA interference (RNAi) with synthetic siRNA suffers from lower silencing efficacy, off-target effects and is cost-intensive, especially for functional genomic studies. With the explosion of fungal genomic information, there is an increasing need to analyze gene function in a rapid manner. Therefore, studies were performed in order to investigate the efficacy of gene silencing induced by RNase III-diced-siRNAs (d-siRNA) in model filamentous fungus, Aspergillus nidulans.

Methodology/Principal Findings

Stable expression of heterologous reporter gene in A. nidulans eases the examination of a new RNAi-induction route. Hence, we have optimized Agrobacterium tumefaciens-mediated transformation (AMT) of A. nidulans for stable expression of sGFP gene. This study demonstrates that the reporter GFP gene stably introduced into A. nidulans can be effectively silenced by treatment of GFP-d-siRNAs. We have shown the down-regulation of two endogenous genes, AnrasA and AnrasB of A. nidulans by d-siRNAs. We have also elucidated the function of an uncharacterized Ras homolog, rasB gene, which was found to be involved in hyphal growth and development. Further, silencing potency of d-siRNA was higher as compared to synthetic siRNA duplex, targeting AnrasA. Silencing was shown to be sequence-specific, since expression profiles of other closely related Ras family genes in d-siRNA treated AnrasA and AnrasB silenced lines exhibited no change in gene expression.

Conclusions/Significance

We have developed and applied a fast, specific and efficient gene silencing approach for elucidating gene function in A. nidulans using d-siRNAs. We have also optimized an efficient AMT in A. nidulans, which is useful for stable integration of transgenes.

Strategies and validation for siRNA-based therapeutics for the reversal of multi-drug resistance in cancer

Resistance of cancer cells to anticancer drugs is the main reason for the failure of traditional cancer treatments. Various cellular components and different loops within the signaling pathways contribute to drug resistance which could be modulated with the aim to restore drug efficacy. Unveiling the molecular mechanisms for cancer drug resistance has now paved the way for the development of novel approaches to regulate the response rates to anticancer drugs at the genetic level. The recent progress on identification and validation of the vital genes directly or indirectly involved in development of cancer drug resistance with the aid of the specific knock down ability of RNA interference technology is discussed in this review.

Applications and potential toxicity of magnetic iron oxide nanoparticles

Owing to their unique physical and chemical properties, magnetic iron oxide nanoparticles have become a powerful platform in many diverse aspects of biomedicine, including magnetic resonance imaging, drug and gene delivery, biological sensing, and hyperthermia. However, the biomedical applications of magnetic iron oxide nanoparticles arouse serious concerns about their pharmacokinetics, metabolism, and toxicity. In this review, the updated research on the biomedical applications and potential toxicity of magnetic iron oxide nanoparticles is summarized. Much more effort is required to develop magnetic iron oxide nanoparticles with improved biocompatible surface engineering to achieve minimal toxicity, for various applications in biomedicine.

Local applications of myostatin-siRNA with atelocollagen increase skeletal muscle mass and recovery of muscle function

Background

Growing evidence suggests that small-interfering RNA (siRNA) can promote gene silencing in mammalian cells without induction of interferon synthesis or nonspecific gene suppression. Recently, a number of highly specific siRNAs targeted against disease-causing or disease-promoting genes have been developed. In this study, we evaluate the effectiveness of atelocollagen (ATCOL)-mediated application of siRNA targeting myostatin (Mst), a negative regulator of skeletal muscle growth, into skeletal muscles of muscular dystrophy model mice.

Methods and Findings

We injected a nanoparticle complex containing myostatin-siRNA and ATCOL (Mst-siRNA/ATCOL) into the masseter muscles of mutant caveolin-3 transgenic (mCAV-3Tg) mice, an animal model for muscular dystrophy. Scrambled (scr) -siRNA/ATCOL complex was injected into the contralateral muscles as a control. Two weeks after injection, the masseter muscles were dissected for histometric analyses. To investigate changes in masseter muscle activity by local administration of Mst-siRNA/ATCOL complex, mouse masseter electromyography (EMG) was measured throughout the experimental period via telemetry. After local application of the Mst-siRNA/ATCOL complex, masseter muscles were enlarged, while no significant change was observed on the contralateral side. Histological analysis showed that myofibrils of masseter muscles treated with the Mst-siRNA/ATCOL complex were significantly larger than those of the control side. Real-time PCR analysis revealed a significant downregulation of Mst expression in the treated masseters of mCAV-3Tg mice. In addition, expression of myogenic transcription factors was upregulated in the Mst-siRNA-treated masseter muscle, while expression of adipogenic transcription factors was significantly downregulated. EMG results indicate that masseter muscle activity in mCAV-3Tg mice was increased by local administration of the Mst-siRNA/ATCOL complex.

Conclusion

These data suggest local administration of Mst-siRNA/ATCOL complex could lead to skeletal muscle hypertrophy and recovery of motor disability in mCAV-3Tg mice. Therefore, ATCOL-mediated application of siRNA is a potential tool for therapeutic use in muscular atrophy diseases.

Lack of correlation between predicted and actual off-target effects of short-interfering RNAs targeting the human papillomavirus type 16 E7 oncogene

Background:

When designing therapeutic short-interfering RNAs (siRNAs), off-target effects (OTEs) are usually predicted by computational quantification of messenger RNAs (mRNAs) that contain matches to the siRNA seed sequence in their 3′ UTRs. It is assumed that the higher the number of predicted transcriptional OTEs, the greater the size of the actual OTE signature and the more detrimental the phenotypic consequences in target-negative cells.

Methods:

We tested this general assumption by investigating the OTEs of potential therapeutic siRNAs targeting the human papillomavirus (HPV) type-16 E7 oncogene. We studied HPV-negative squamous epithelial cells, from normal cervix (NCx) and skin (HaCaT), which would be vulnerable to ‘bystander' OTEs following transfection in vivo.

Results:

We observed no correlation between the number of computationally predicted OTEs and the actual number of seed-dependent OTEs (P=0.76). On average only 20.5% of actual transcriptional OTEs were seed-dependent (i.e., predicted). The unpredicted OTEs included stimulation of innate immune pathways, as well as indirect (downstream) effects of other OTEs, which affected important cancer-associated pathways. Although most significant OTEs observed were seen in both NCx and HaCaT cells, only 0–5.9% of differentially expressed genes overlapped between the two cell types.

Conclusion:

These data do not support the assumption that actual OTEs correlate well with predicted OTEs.

Bifunctional short hairpin RNA (bi-shRNA): design and pathway to clinical application

The discovery of RNA interference (RNAi) engendered great excitement and raised expectations regarding its potential applications in biomedical research and clinical usage. Over the ensuing years, expanded understanding of RNAi and preliminary results from early clinical trials tempered enthusiasm with realistic appraisal resulting in cautious optimism and a better understanding of necessary research and clinical directions. As a result, data from more recent trials are beginning to show encouraging positive clinical outcomes. The capability of delivering a pharmacologically effective dose to the target site while avoiding adverse host reactions still remains a challenge although the delivery technology continues to improve. We have developed a novel vector-driven bifunctional short hairpin RNA (bi-shRNA) technology that harnesses both cleavage-dependent and cleavage-independent RISC loading pathways to enhance knockdown potency. Consequent advantages provided by the bi-shRNA include a lower effective systemic dose than comparator siRNA/shRNA to minimize the potential for off-target side effects, due to its ability to induce both a rapid (inhibition of protein translation) and delayed (mRNA cleavage and degradation) targeting effect depending on protein and mRNA kinetics, and a longer duration of effectiveness for clinical applications. Here, we provide an overview of key molecular methods for the design, construction, quality control, and application of bi-shRNA that we believe will be useful for others interested in utilizing this technology.

Advances in polymeric and inorganic vectors for nonviral nucleic acid delivery

Nonviral systems for nucleic acid delivery offer a host of potential advantages compared with viruses, including reduced toxicity and immunogenicity, increased ease of production and less stringent vector size limitations, but remain far less efficient than their viral counterparts. In this article we review recent advances in the delivery of nucleic acids using polymeric and inorganic vectors. We discuss the wide range of materials being designed and evaluated for these purposes while considering the physical requirements and barriers to entry that these agents face and reviewing recent novel approaches towards improving delivery with respect to each of these barriers. Furthermore, we provide a brief overview of past and ongoing nonviral gene therapy clinical trials. We conclude with a discussion of multifunctional nucleic acid carriers and future directions.

Reconsideration of in-silico siRNA design based on feature selection: a cross-platform data integration perspective

RNA interference via exogenous short interference RNAs (siRNA) is increasingly more widely employed as a tool in gene function studies, drug target discovery and disease treatment. Currently there is a strong need for rational siRNA design to achieve more reliable and specific gene silencing; and to keep up with the increasing needs for a wider range of applications. While progress has been made in the ability to design siRNAs with specific targets, we are clearly at an infancy stage towards achieving rational design of siRNAs with high efficacy. Among the many obstacles to overcome, lack of general understanding of what sequence features of siRNAs may affect their silencing efficacy and of large-scale homogeneous data needed to carry out such association analyses represents two challenges. To address these issues, we investigated a feature-selection based in-silico siRNA design from a novel cross-platform data integration perspective. An integration analysis of 4,482 siRNAs from ten meta-datasets was conducted for ranking siRNA features, according to their possible importance to the silencing efficacy of siRNAs across heterogeneous data sources. Our ranking analysis revealed for the first time the most relevant features based on cross-platform experiments, which compares favorably with the traditional in-silico siRNA feature screening based on the small samples of individual platform data. We believe that our feature ranking analysis can offer more creditable suggestions to help improving the design of siRNA with specific silencing targets. Data and scripts are available at http://csbl.bmb.uga.edu/publications/materials/qiliu/siRNA.html.

Degradable Dextran Particles for Gene Delivery Applications

Successful gene therapy depends both on the effective transport and the stable expression of therapeutic genes to produce and regulate disease related proteins. In this context, non-viral gene delivery vehicles are regarded as one of the most promising approaches for the efficient and safe transport of genetic material to and into the target cells. This short review describes the development of novel particulate delivery vehicles based on the biopolymer dextran. This multifunctional platform was designed to safely transport genetic material across cell membranes, followed by an acid triggered release that causes overall high transfection efficiency. The biocompatibility and its unique tunability differentiate this new carrier system from previous particle systems, showing high potential for the treatment of several disease models in RNA interference related applications.

N-Alkyl-PEI-functionalized iron oxide nanoclusters for efficient siRNA delivery

Small-interfering RNA (siRNA) is an emerging class of therapeutics, which works by regulating the expression of a specific gene involved in disease progression. Despite the promises, effective transport of siRNA with minimal side effects remains a challenge. In this study, a nonviral nanoparticle gene carrier is developed and its efficiency for siRNA delivery and transfection is validated at both in vitro and in vivo levels. Such a nanocarrier, abbreviated as Alkyl-PEI2k-IO, was constructed with a core of iron oxide nanoparticles (IOs) and a shell of alkylated polyethyleneimine of 2000 Da [corrected] molecualr weight (Alkyl-PEI2k). It is found to be able to bind with siRNA, resulting in well-dispersed nanoparticles with a controlled clustering structure and narrow size distribution. Electrophoresis studies show that the Alkyl-PEI2k-IOs could retard siRNA completely at N:P ratios (i.e., PEI nitrogen to nucleic acid phosphate) above 10, protect siRNA from enzymatic degradation in serum, and release complexed siRNA efficiently in the presence of polyanionic heparin. The knockdown efficiency of the siRNA-loaded nanocarriers is assessed with 4T1 cells stably expressing luciferase (fluc-4T1) and further, with a fluc-4T1 xenograft model. Significant down-regulation of luciferase is observed, and unlike high-molecular-weight analogues, the Alkyl-PEI2k-coated IOs show good biocompatibility. In conclusion, Alkyl-PEI2k-IOs demonstrate highly efficient delivery of siRNA and an innocuous toxic profile, making it a potential carrier for gene therapy.

Anti-CD22 antibody targeting of pH-responsive micelles enhances small interfering RNA delivery and gene silencing in lymphoma cells

The application of small interfering RNA (siRNA) for cancer treatment is a promising strategy currently being explored in early phase clinical trials. However, efficient systemic delivery limits clinical implementation. We developed and tested a novel delivery system comprised of (i) an internalizing streptavidin-conjugated monoclonal antibody (mAb-SA) directed against CD22 and (ii) a biotinylated diblock copolymer containing both a positively charged siRNA condensing block and a pH-responsive block to facilitate endosome release. The modular design of the carrier facilitates the exchange of different targeting moieties and siRNAs to permit its usage in a variety of tumor types. The polymer was synthesized using the reversible addition fragmentation chain transfer (RAFT) technique and formed micelles capable of binding siRNA and mAb-SA. A hemolysis assay confirmed the predicted membrane destabilizing activity of the polymer under acidic conditions typical of the endosomal compartment. Enhanced siRNA uptake was demonstrated in DoHH2 lymphoma and transduced HeLa-R cells expressing CD22 but not in CD22 negative HeLa-R cells. Gene knockdown was significantly improved with CD22-targeted vs. nontargeted polymeric micelles. Treatment of DoHH2 cells with CD22-targeted polymeric micelles containing 15 nmol/l siRNA produced 70% reduction of gene expression. This CD22-targeted polymer carrier may be useful for siRNA delivery to lymphoma cells.

SIRT3 and cancer: tumor promoter or suppressor?

Sirtuins (SIRT1-7), the mammalian homologues of the Sir2 gene in yeast, have emerging roles in age-related diseases, such as cardiac hypertrophy, diabetes, obesity, and cancer. However, the role of several sirtuin family members, including SIRT1 and SIRT3, in cancer has been controversial. The aim of this review is to explore and discuss the seemingly dichotomous role of SIRT3 in cancer biology with particular emphasis on its potential role as a tumor promoter and tumor suppressor. This review will also discuss the potential role of SIRT3 as a novel therapeutic target to treat cancer.

See, reach, treat: ultrasound-triggered image-guided drug delivery

The integration of therapeutic interventions with diagnostic imaging has been recognized as one of the next technological developments that will have a major impact on medical treatments. Therapeutic applications using ultrasound, for example thermal ablation, hyperthermia or ultrasound-induced drug delivery, are examples for image-guided interventions that are currently being investigated. While thermal ablation using magnetic resonance-guided high-intensity focused ultrasound is entering the clinic, ultrasound-mediated drug delivery is still in a research phase, but holds promise to enable new applications in localized treatments. The use of ultrasound for the delivery of drugs has been demonstrated, particularly in the field of cardiology and oncology for a variety of therapeutics ranging from small-molecule drugs to biologics and nucleic acids exploiting temperature- or pressure-mediated delivery schemes.

Adenovirus-mediated transfer of tris-shRNAs induced apoptosis of nasopharyngeal carcinoma cell in vitro and in vivo

RNA interference (RNAi) is an evolutionary conserved mechanism for specific gene silencing. There are currently numerous cancer therapy clinical trials based on RNAi technology. Using an adenoviral system as a delivery mediator of RNAi, we investigated the therapeutic effects of targeting three genes simultaneously in vitro and in vivo. In this study, we constructed an recombinant adenoviral shRNA expression system as Adv-pEGFP-shVEGF-shTERT-shBcl-xl for multi-genes silencing. Our results showed that the adenoviral vector can achieve above 90% of transfection efficiency and induced obvious apoptosis in CNE-2 cell both in vitro and in vivo compared with targeting the TERT alone or controlled group.

SiRNA-mediated silencing of the RUNX2 gene inhibits proliferation and induces apoptosis in human gastric cancer cell line SGC7901

AIM: To detect the expression of runt-related transcription factor gene 2 (RUNX2) in human gastric cancer cell line SGC7901 and to investigate the influence of small interfering RNA (siRNA)-mediated silencing of the RUNX2 gene on the proliferation and apoptosis of SGC7901 cells.

METHODS: SGC7901 cells were divided into three groups: blank control group, negative control group (transfected with an empty vector), and experiment group (transfected with RUNX2 siRNA). After SGC7901 cells were transfected with RUNX2 siRNA, the mRNA and protein expression of RUNX2 was examined by RT-PCR and Western blot, respectively; cell proliferation was evaluated by MTT assay; and cell apoptosis was detected by flow cytometry (FCM).

RESULTS: Compared with cells of the blank control group, the expression of RUNX2 mRNA (0.27 ± 0.068 vs 0.45 ± 0.058, F = 75.6, P < 0.01) and protein (F = 123.8, P < 0.001) was down-regulated in cells transfected with RUNX2 siRNA. At 24, 48, and 72 h after transfection, the proliferation rates of SGC7901 cells transfected with RUNX2 siRNA were significantly lower than those of non-transfected cells (0.23 ± 0.039 vs 0.32 ± 0.012; 0.31 ± 0.037 vs 0.45 ± 0.074; 0.52 ± 0.021 vs 0.72 ± 0.006; F = 173.744, 14.012, 253.145; all P < 0.001). The apoptosis rate of SGC7901 cells transfected with RUNX2 siRNA was significantly higher than those of cells of the blank control group and negative control (45.65% ± 0.64% vs 4.46% ± 0.27%, 4.23% ± 0.33%, both P < 0.01).

CONCLUSION: RUNX2 expression was detected in SGC7901 cells. SiRNA-mediated silencing of the RUNX2 gene can inhibit proliferation and induce apoptosis in SGC7901 cells. RUNX2 may be a new gene therapy target for gastric cancer.

The vicious circle between oxidative stress and inflammation in atherosclerosis

The initial event in atherogenesis is the increased transcytosis of low density lipoprotein, and its subsequent deposition, retention and modification in the subendothelium. It is followed by the infiltration of activated inflammatory cells from the coronary circulation into the arterial wall. There they secrete reactive oxygen species (ROS) and produce oxidized lipoproteins capable of inducing endothelial cell apoptosis, and thereby plaque erosion. Activated T lymphocytes, macrophages and mast cells, accumulate in the eroded plaque where they secrete a variety of proteases capable of inducing degradation of extracellular proteins, thereby rendering the plaques more prone to rupture. This review summarizes the recent advancements in the understanding of the roles of ROS and oxidized lipoproteins in the activation of inflammatory cells and inducing signalling pathways related to cell death and apoptosis. In addition, it presents evidence that this vicious circle between oxidative stress and inflammation does not only occur in the diseased arterial wall, but also in adipose tissues. There, oxidative stress and inflammation impair adipocyte maturation resulting in defective insulin action and adipocytokine signalling. The latter is associated with increased infiltration of inflammatory cells, loss of anti-oxidant protection and cell death in the arterial wall.