siRNA agents inhibit oncogene expression and attenuate human tumor cell growth

Co-targeting NRF2 potentially enhances the in vitro anticancer effects of paclitaxel in gastric cancer cells

BACKGROUND

Gastric cancer (GC) is a highly chemoresistant malignancy with a poor prognosis. Paclitaxel's low response rate as second-line chemotherapy for advanced GC has prompted intensive research into its molecular basis and prospective targeted therapies to enhance its therapeutic efficacy. The objective of this study was to investigate the synergistic effects of NRF2 silencing in combination with paclitaxel treatment on GC cell viability, apoptosis, proliferation, autophagy, and migration.

METHODS

\After the siRNA-mediated silencing of NRF2 in AGS cells, the transfection efficacy was evaluated by qRT-PCR. The MTT assay was then applied to assess cell viability, followed by flow cytometry analysis for apoptosis, proliferation, and autophagy in AGS cells treated with NRF2 siRNA, paclitaxel, or their combination. Thereafter, the migration of cells was measured using a wound-healing assay. Ultimately, the relative gene expression levels of apoptotic (Bax, Caspase-3, and Caspase-9), anti-apoptotic (Bcl-2), metastatic (MMP-2), and cell cycle (P53) genes were measured by qRT-PCR in all experiment groups to further assess the molecular basis for the combination therapy.

RESULTS

NRF2 siRNA transfection significantly enhanced paclitaxel-induced apoptosis and sensitized AGS cells to paclitaxel via modulating the expression of apoptosis-related genes including Bcl-2, Bax, Caspase-3, and Caspase-9. Besides, NRF2 siRNA and paclitaxel synergistically induced cell cycle arrest at the G2 phase, promoted autophagy activation, and inhibited AGS cell migration via MMP-2 downregulation. Additionally, P53, a key regulator of cell growth, was significantly upregulated in the treated groups compared to the control group.

CONCLUSIONS

Our findings suggest that paclitaxel combined with siRNA-mediated silencing of NRF2 might represent a promising therapeutic strategy for GC, however further translational and clinical research are warranted.

Tumor- and Fibroblast-Derived Cell-Free DNAs Differently Affect the Progression of B16 Melanoma In Vitro and In Vivo

It is widely postulated that the majority of pathologically elevated extracellular or cell-free DNA (cfDNA) in cancer originates from tumor cells; however, evidence has emerged regarding the significant contributions of other cells from the tumor microenvironment. Here, the effect of cfDNA originating from murine B16 melanoma cells and L929 fibroblasts on B16 cells was investigated. It was found that cfDNAL929 increased the viability and migration properties of B16 cells in vitro and their invasiveness in vivo. In contrast, cfDNAB16 exhibited a negative effect on B16 cells, reducing their viability and migration in vitro, which in vivo led to decreased tumor size and metastasis number. It was shown that cell treatment with both cfDNAs resulted in an increase in the expression of genes encoding DNases and the oncogenes Braf, Kras, and Myc. cfDNAL929-treated cells were shown to experience oxidative stress. Gene expression changes in the case of cfDNAB16 treatment are well correlated with the observed decrease in proliferation and migration of B16 cells. The obtained data may indicate the possible involvement of fibroblast DNA in the tumor microenvironment in tumor progression and, potentially, in the formation of new tumor foci due to the transformation of normal cells.

Review on Metal-Based Theranostic Nanoparticles for Cancer Therapy and Imaging

Theranostic agents are promising due to their ability to diagnose, treat and monitor different types of cancer using a variety of imaging modalities. The advantage specifically of nanoparticles is that they can accumulate easily at the tumor site due to the large gaps in blood vessels near tumors. Such high concentration of theranostic agents at the target site can lead to enhancement in both imaging and therapy. This article provides an overview of nanoparticles that have been used for cancer theranostics, and the different imaging, treatment options and signaling pathways that are important when using nanoparticles for cancer theranostics. In particular, nanoparticles made of metal elements are emphasized due to their wide applications in cancer theranostics. One important aspect discussed is the ability to combine different types of metals in one nanoplatform for use as multimodal imaging and therapeutic agents for cancer.

iRGD-modified exosomes-delivered BCL6 siRNA inhibit the progression of diffuse large B-cell lymphoma

Clinical applications of siRNA therapeutics have been limited by the immunogenicity of the siRNA and low efficiency of siRNA delivery to target cells. Recently, evidence have shown that exosomes, endogenous nano-vesicles, can deliver siRNA to the tumor tissues in mice. Here, to reduce immunogenicity, we selected immature dendritic cells (DCs) to produce exosomes. In addition, tumor targeting was achieved by engineering the DCs to express exosomal membrane protein (Lamp2b), fused to av integrin-specific iRGD peptide (CRGDKGPDC). Next, iRGD targeted exosomes (iRGD-Exo) were isolated from the transfected DCs, and then the isolated exosomes were loaded with BCL6 siRNA by electroporation. Our results found that integrin (αvβ3) receptors were highly expressed on OCI-Ly8 cells. In addition, iRGD-Exo showed high targeting ability with avβ3 integrins positive OCI-Ly8 cells. Significantly, iRGD-Exo loaded with BCL6 siRNA suppressed DLBCL cell proliferation in vitro. Furthermore, intravenously injected iRGD-Exo delivered BCL6 siRNA to tumor tissues, resulting in inhibition of tumor growth in DLBCL. Meanwhile, exosomes mediated BCL6 siRNA delivery did not exhibit appreciable toxicity in mice. Collectively, our study demonstrates a therapeutic potential of exosomes as a promising vehicle for RNAi delivery to treat DLBCL.

Amount of Escape Estimation Based on Bayesian and MCMC Approaches for RNA Interference

The amount of short interfering RNA (siRNA) escaping from the endosome has a significant impact on the efficiency of RNAi. In general, the initial injected amount of siRNAs during the experiment is known, and also the amount of siRNAs after the experiment can be revealed by the level of mRNA measured. However, it is impossible to measure the amount of siRNAs that escape from the endosome and really take part in the chemical reaction of RNAi by detecting the biological organism and its tissues. Inspired by the bottleneck effect in the virus, we introduce the Bayesian approach to infer the amount of escape based on a single type and multiple types of siRNA, respectively. With the consideration of the large calculation quantity of the accurate posterior distribution and the unavailable analytic expression of the likelihood function, our article proposes to take samples by the improved Markov chain Monte Carlo (MCMC) method. The article takes the silencing gene of the synthesis of chitin and the interfering multiple target oncogene as numerical examples to show that our improved MCMC method has higher operation efficiency compared to the Bayesian approach. Our research models siRNA endosome escape using statistical methods for the first time. It perhaps provides a theoretical basis to decrease the cost of a biotic experiment for the future and the standardized statistical approaches for the amount of escape estimation.

Cationic vesicles for efficient shRNA transfection in the MCF-7 breast cancer cell line

INTRODUCTION

Novel and safe delivery solutions for RNAi therapeutics are essential to obtain the full potential of cancer gene therapy.

METHODS

In this study, cationic vesicular nanocarrier was applied for delivering lnc urothelial carcinoma-associated 1 (lnc UCA1) shRNA expression vector to MCF-7 cells. The physicochemical characteristics, cytotoxicity, and transfection efficiency of cationic vesicles prepared from various molar ratios of amphiphilic surfactant Tween 80 (T), squalene (S), cationic charge lipid didodecyldimethylammonium bromide, and polyethylenimine were investigated. The particle sizes of the vesicles in the nanosize range were determined by dynamic light scattering and transmission electron microscopy.

RESULTS

Gel protection assay with agarose gel electrophoresis showed cationic vesicles can protect the shRNA plasmid from DNase 1 enzyme. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt result showed no significant cytotoxicity was caused in MCF-7 cancer cell line by (T:S):polyethylenimine cationic vesicles. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt assay, fluorescence microscope images, and flow cytometry analyses confirmed that (T:S)1,040 μM with 4.3 μg/mL of PEI vesicles provided effective transfection without significant cytotoxicity. Furthermore, we found efficient UCA1 shRNA transfection and significant (P<0.05) cell cycle arrest and apoptosis in MCF-7 cancer cells.

CONCLUSION

The novel nonviral vesicular nanocarrier, (T:S)1,040 μM with 4.3 μg/mL of PEI, might be safe and efficient for cancer gene therapy and can be used in further in vitro and in vivo studies.

Rolling Circle Transcription for the Self-Assembly of Multimeric RNAi Structures and Its Applications in Nanomedicine

The enzymatic process of rolling circle transcription (RCT) enables self-assembly of multimeric RNAi structures from a circular DNA template. The self-assembled RNAi structures can be manipulated easily by simple base pairing rules with short DNA fragments for constructing multifunctional nanoparticles in the field of nanomedicine. Here we describe the method to generate multifunctional RNAi nanoparticles applicable in nanomedicine.

miR-17-92基因簇在肿瘤发生发展中作用的研究进展

肿瘤是威胁全世界人类健康和影响社会经济的重要因素. 近年来, 随着经济的发展, 肿瘤的发病率呈明显上升趋势, 但是其病因尚未完全阐明. 越来越多的证据显示肿瘤的发生和遗传因素有关, 随着病理生理学和遗传学的发展, 许多学者认为生物标志物可以预测癌症甚至指导临床治疗. 微小RNA(microRNA, miRNA)是非编码小分子RNA, 在发育、生理、病理过程以及肿瘤发生等环节中起着重要的调节作用. miR-17-92基因簇是研究较为深入、最有特点的miRNA, 被认为是原癌基因miRNA的代表, 在多种肿瘤的发生发展中起着至关重要的作用. 本文就miR-17-92基因簇在肿瘤发生发展中的作用及功能进行综述.

[RNA interference of HERC4 inhibits proliferation, apoptosis and migration of cervical cancer Hela cells]

OBJECTIVE

To explore the effects of silencing HERC4 on the proliferation, apoptosis, and migration of cervical cancer cell line Hela and the possible molecular mechanisms.

METHODS

Three HERC4-specific small interfering RNAs (siRNAs) were transfected into Hela cells, and HERC4 expression in the cells was examined with Western blotting. CCK-8 assay, annexin V-FITC/PI assay, and wound healing assay were used to assess the effect of HERC4 silencing on the proliferation, apoptosis and migration ability of Hela cells. The expression levels of cyclin D1 and Bcl-2 in the cells were detected using Western blotting.

RESULTS

Transfection of siRNA-3 resulted in significantly decreased HERC4 protein expression (P<0.01). HERC4 silencing by siRNA-3 markedly suppressed the proliferation and migration of Hela cells, increased the apoptosis rate (P<0.01) and reduced the expression levels of cyclin D1 and Bcl-2 (P<0.01).

CONCLUSION

Silencing of HERC4 efficiently inhibits the proliferation, migration, and invasion of Hela cells in vitro, and the underlying mechanisms may involve the down-regulation of cyclin D1 and Bcl-2.

Design of a platform technology for systemic delivery of siRNA to tumours using rolling circle transcription

For therapeutic applications of siRNA, there are technical challenges with respect to targeted and systemic delivery. We here report a new siRNA carrier, RNAtr NPs, in a way that multiple tandem copies of RNA hairpins as a result of rolling circle transcription (RCT) can be readily adapted in tumour-targeted and systemic siRNA delivery. RNAtr NPs provide a means of condensing large amounts of multimeric RNA transcripts into the compact nanoparticles, especially without the aid of polycationic agents, and thus reduce the risk of immunogenicity and cytotoxicity by avoiding the use of synthetic polycationic reagents. This strategy allows the design of a platform technology for systemic delivery of siRNA to tumour sites, because RCT reaction, which enzymatically generates RNA polymers in multiple copy numbers at low cost, can lead to directly accessible routes to targeted and systemic delivery. Therefore, RNAtr NPs suggest great potentials as the siRNA therapeutics for cancer treatment.

RNA interference has provided a promising tool to suppress the expression of specific genes associated with human diseases. Here, the authors present a platform technology for the systemic delivery of siRNA to tumour sites using rolling circle transcription.

Suppression of tumor growth in lung cancer xenograft model mice by poly(sorbitol-co-PEI)-mediated delivery of osteopontin siRNA

Small interfering RNA (siRNA)-mediated gene silencing represents a promising strategy for treating diseases such as cancer; however, specific gene silencing requires an effective delivery system to overcome the instability and low transfection efficiency of siRNAs. To address this issue, a polysorbitol-based transporter (PSOT) was prepared by low molecular weight branched polyethylenimine (bPEI) crosslinked with sorbitol diacrylate (SDA). Osteopontin (OPN) gene, which is highly associated with non-small cell lung cancer (NSCLC) was targeted by siRNA therapy using siRNA targeting OPN (siOPN). Characterization study confirmed that PSOT formed compact complexes with siOPN and protected siOPN against degradation by RNase. PSOT/siOPN complexes demonstrated low cytotoxicity and enhanced transfection efficiency in vitro, suggesting that this carrier may be suitable for gene silencing. In the A549 and H460 lung cancer cell lines, PSOT/siOPN complexes demonstrated significant silencing efficiency at both RNA and protein levels. To study in vivo tumor growth suppression, two lung cancer cell-xenograft mouse models were prepared and PSOT/siOPN complexes were delivered into the mice through intravenous injection. The siOPN-treated groups demonstrated significantly reduced OPN expression at both the RNA and protein levels as well as suppression of tumor volume and weight. Taken together, siOPN delivery using PSOT may present an effective and novel therapeutic system for lung cancer treatment.

Effects of azidothymidine on protein kinase C activity and expression in erythroleukemic cell K562 and acute lymphoblastic leukemia cell HSB-2

Azidothymidine (AZT) is one of the anti-retroviral drugs currently used for the treatment of HIV-infected patients. Several other effects of the drug have been studied in vitro, such as the alterations of some enzymes, the inhibition of cell proliferation, and the increase of transferrin receptor expression. In this study, we investigated the alterations of protein kinase C (PKC) activity, PKCα and PKCβII expressions and plasmatic membrane fluidity induced by AZT in two cancer cell lines, human chronic myeloid (K562) and human acute lymphoblastic (HSB-2) leukemia cells, respectively. The results showed that both PKC activity and membrane fluidity in HSB-2 cells increased after 24 h of drug incubation. PKCα expression in HSB-2 cells decreased after 48 h of AZT exposure, when the cell growth also decreased. However, in K562 cells, the PKCα and PKCβII expressions enhanced in the presence of the drug when the growth was inhibited. The results indicate that AZT is less effective in inhibiting the growth of acute lymphoblastic HSB-2 leukemia cells than inhibiting that of chronic myeloid K562 cells. In fact, after 24 h exposure, the HSB-2 cell growth decreased less than K562 cell growth.

Utilization of a PNA-peptide conjugate to induce a cancer protease-responsive RNAi effect

We designed a new siRNA system which turns on RNAi responding to a cancer cell-specific protease by using a peptide nucleic acid (PNA)-peptide conjugate.

SiRNA gene therapy using albumin as a carrier

RNA interference or post-transcriptional gene silencing is one of the latest, innovative, highly specific, and efficient technologies for gene therapy application in molecular oncology. It is already a well-established research tool for analyses of molecular mechanisms for various diseases including cancer as it efficiently silences the expression of genes of interest. However, for its proper therapeutic use, an efficient tumor-specific in-vivo delivery mechanism is essential. Many scientific groups and companies are involved in the development of efficient in-vivo delivery mechanisms for small interfering RNA, but are still struggling. The present article suggests utilization of albumin as a delivery module for small interfering RNA as it is an endogenous natural nanoparticle known for its binding properties to various endogenous metabolites, drugs, and metal ions.

Bcl-2 down-regulation by small interfering RNA induces Beclin1-dependent autophagy in human SGC-7901 cells

While Bcl-2 protein is involved in the regulation of apoptosis, recent research showed that Beclin1, described as the essential autophagy effector and haploinsufficient tumor suppressor, was originally isolated as a Bcl-2 interacting protein. Beclin1 interacts with Bcl-2 through a BH3 domain; nevertheless, the function of the anti-apoptotic gene, Bcl-2, in autophagy is not well understood. We explored the role of Bcl-2 in autophagy in human SGC-7901 cells in which Bcl-2 is overexpressed. Knockdown of Bcl-2 by small interfering RNA in human SGC-7901 cells downregulated Bcl-2 protein levels ∼82% and induced autophagy. Beclin1 protein, the first identified autophagy gene product, was induced by as much as 58%. Transmission electron microscopy and DNA fragmentation assay showed that autophagy was enhanced, but not apoptosis, in Bcl-2 siRNA treated cells. The results provide evidence that knockout the anti-apoptotic gene Bcl-2 induces autophagy in SGC-7901 cells and Bcl-2 specific siRNA may be used as a potential therapeutic strategy in gastric cancer cells that overexpress Bcl-2.

Local delivery of chitosan/VEGF siRNA nanoplexes reduces angiogenesis and growth of breast cancer in vivo

Vascular endothelial growth factor (VEGF) is the important angiogenic factor associated with tumor growth and metastasis in a wide variety of solid tumors. The aim of this study is to investigate the tumor suppressive effect of chitosan/small interfering RNA (siRNA)-VEGF nanoplexes in the rat breast cancer model. Chitosan/siRNA nanoplexes (siVEGF-A, siVEGFR-1, siVEGFR-2) and NRP-1 were prepared in a 15 to1 ratio and injected (intratumorally) into the breast-tumor-bearing Sprague-Dawley rats. Tumor volumes were measured during 21 days. To investigate the effect of chitosan/siRNA nanoplexes on VEGF expression in tumors, VEGF was analyzed with immunohistochemistry and western blotting. The mRNA levels of VEGF in tumor samples were determined with real-time PCR (RT-PCR). After siRNA treatment, a marked reduction in tumor volumes was measured in complex-injected rats (97%). Free siRNA injection showed lower tumor inhibition. Reduction of VEGF protein was also shown with western blotting and immunohistochemistry. Similar results were obtained with RT-PCR also. These results indicate that the chitosan/siRNA targeting to VEGF nanoplexes have a remarkably suppressive effect on VEGF expression and tumor volume in breast cancer model of rats.

Delivery of intracellular-acting biologics in pro-apoptotic therapies

The recent elucidation of molecular regulators of apoptosis and their roles in cellular oncogenesis has motivated the development of biomacromolecular anticancer therapeutics that can activate intracellular apoptotic signaling pathways. Pharmaceutical scientists have employed a variety of classes of biologics toward this goal, including antisense oligodeoxynucleotides, small interfering RNA, proteins, antibodies, and peptides. However, stability in the in vivo environment, tumor-specific biodistribution, cell internalization, and localization to the intracellular microenvironment where the targeted molecule is localized pose significant challenges that limit the ability to directly apply intracellular-acting, pro-apoptotic biologics for therapeutic use. Thus, approaches to improve the pharmaceutical properties of therapeutic biomacromolecules are of great significance and have included chemically modifying the bioactive molecule itself or formulation with auxiliary compounds. Recently, promising advances in delivery of pro-apoptotic biomacromolecular agents have been made using tools such as peptide "stapling", cell penetrating peptides, fusogenic peptides, liposomes, nanoparticles, smart polymers, and synergistic combinations of these components. This review will discuss the molecular mediators of cellular apoptosis, the respective mechanisms by which these mediators are dysregulated in cellular oncogenesis, the history and development of both nucleic-acid and amino-acid based drugs, and techniques to achieve intracellular delivery of these biologics. Finally, recent applications where pro-apoptotic functionality has been achieved through delivery of intracellular-acting biomacromolecular drugs will be highlighted.

MITF-siRNA formulation is a safe and effective therapy for human melasma

It is unclear whether siRNA-based agents can be a safe and effective therapy for diseases. In this study, we demonstrate that microphthalmia-associated transcription factor-siRNA (MITF-siR)-silenced MITF gene expression effectively induced a significant reduction in tyrosinase (TYR), tyrosinase-related protein 1, and melanocortin 1 receptor (MC1R) levels. The siRNAs caused obvious inhibition of melanin synthesis and melanoma cell apoptosis. Using a novel type of transdermal peptide, we developed the formulation of an MITF-siR cream. Results demonstrated that hyperpigmented facial lesions of siRNA-treated subjects were significantly lighter after 12 weeks of therapy than before treatment (P < 0.001); overall improvement was first noted after 4 weeks of siRNA treatment. At the end of treatment, clinical and colorimetric evaluations demonstrated a 90.4% lightening of the siRNA-treated lesions toward normal skin color. The relative melanin contents in the lesions and adjacent normal skin were decreased by 26% and 7.4%, respectively, after treatment with the MITF-siR formulation. Topical application of siRNA formulation significantly lightens brown facial hypermelanosis and lightens normal skin in Asian individuals. This treatment represents a safe and effective therapy for melasma, suggesting that siRNA-based agents could be developed for treating other diseases such as melanoma.

Efficient gene silencing in lungs and liver using imidazole-modified chitosan as a nanocarrier for small interfering RNA

Despite high specificity and potency, small interfering RNA (siRNA)-based therapeutics have been limited by their poor biostability and intracellular penetration. Thus, effective nanocarriers that can protect and efficiently deliver siRNA to target cells in vivo are needed. Here we report on the efficiency of imidazole-modified chitosan (chitosan-imidazole-4-acetic acid [IAA])-siRNA nanoparticles to mediate gene silencing after administration via either intravenous (i.v.) or intranasal (i.n.) routes. Poly(ethylene glycol) (PEG)ylated nanoparticles for i.v. delivery demonstrated significant knockdown of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) enzyme in both lung and liver at as low as 1 mg/kg siRNA dose. In addition, the efficient, dose-dependent silencing of apolipoprotein B in the liver was also shown. For i.n. delivery, significant silencing of GAPDH protein expression was seen in the lungs with only 0.5 mg/kg/day siRNA delivered over 3 consecutive days. In summary, imidazole-modified chitosan-IAA nanoparticles are potentially effective carriers for siRNA delivery.

Therapeutic opportunities of small interfering RNA

Formation of small interfering RNA (siRNA) occurs in two steps involving binding of the RNA nucleases to a large double‐stranded RNA (dsRNA) and its cleavage into fragments called siRNA. In the second step, these siRNAs join a multinuclease complex, which degrades the homologous single‐stranded mRNAs. The delivery of siRNA involves viral‐ and non‐viral‐mediated delivery systems; the approaches for chemical modifications have also been developed. It has various therapeutic applications for disorders like cardiovascular diseases, central nervous system (CNS) disorders, cancer, human immunodeficiency virus (HIV), hepatic disorders, etc. The present review gives an overview of the applications of siRNA and their potential for treating many hitherto untreatable diseases.

Dual knockdown of N-ras and epiregulin synergistically suppressed the growth of human hepatoma cells

Hepatocellular carcinoma (HCC) is a major challenge because of its resistance to conventional cytotoxic chemotherapy and radiotherapy. Multi-targeted therapy might be a new option for HCC treatment. Our previous study showed that N-ras gene was activated in HCC and was inhibited by RNA interference. In the present study, we investigated the alternation of gene expression by microarray in N-Ras-siRNA-treated HepG2 cells. The results revealed that the EREG gene, encoding epiregulin, was dramatically up-regulated in response to silence of N-ras. We speculated that the up-regulation of epiregulin was involved in the compensatory mechanism of N-ras knockdown for cell growth. Therefore, we evaluated whether dual silence of N-ras and epiregulin display a greater suppression of cell growth. The results confirmed that dual knockdown of N-ras and epiregulin synergistically inhibited cell growth. Our results also showed that dual knockdown of N-ras and epiregulin significantly induced cell arrest at G0/G1 phase. Furthermore, Western blot assay showed that dual knockdown of N-ras and epiregulin markedly reduced the phosphorylations of ERK1/2, Akt and Rb, and inhibited the expression of cyclin D1. Our findings imply that multi-targeted silence of oncogenes might be an effective treatment for HCC.

Suppression of N-Ras by shRNA-expressing plasmid increases sensitivity of HepG2 cells to vincristine-induced growth inhibition

Oncogenic ras genes relate to the development of human cancers. In this study, we used a plasmid-mediated short-hairpin RNA (shRNA) targeting N-ras gene to combine with clinical drug vincristine (VCR) for the treatment of human hepatoma cells. Our results showed that anti-N-Ras shRNA expression vector (pCSH1-shNR) knocked down the target mRNA and protein. Higher efficacy on growth inhibition was observed when pCSH1-shNR was combined with VCR. This synergistic effect was associated with abrogation of VCR-induced overexpressions of P-glycoprotein and multidrug resistance-associated protein 1 by pCSH1-shNR through downregulations of N-Ras and total Ras. Western blot analysis showed that pCSH1-shNR-induced downregulations of N-Ras and total Ras were potentiated by VCR. Following Ras downregulation, phosphorylations of ERK1/2 and Akt were dramatically inhibited by combinatory treatment. The data showed that pCSH1-shNR-induced inhibition of nuclear factor-kappaB was enhanced by VCR. In addition, the combination of pCSH1-shNR and VCR synergistically inhibited the growth of human hepatoma HepG2 in vivo. Our findings suggested that combination of gene-specific therapeutics and appropriate chemotherapeutic agents might be a promising approach for the treatment of human hepatocellular carcinoma.

Protein kinase C isoforms: Multi-functional regulators of cell life and death

The protein kinase C (PKC) family consists of 10 related serine/threonine protein kinases some of which are critical regulators of cell proliferation, survival and cell death. While early studies relied on broad spectrum chemical activators or inhibitors of this family, the generation of isoform specific tools has greatly facilitated our understanding of the contribution of specific PKC isoforms to cell proliferation and apoptosis. These studies suggest that PKC-alpha, PKC-epsilon, and the atypical PKC's, PKC-lambda/iota and PKC-zeta, preferentially function to promote cell proliferation and survival, while the novel isoform, PKC-delta is an important regulator of apoptosis. The essential role of this kinase family in both cell survival and apoptosis suggests that specific isoforms may function as molecular sensors, promoting cell survival or cell death depending on environmental cues. Given their central role in cell and tissue homeostasis, it is not surprising that the expression or activity of some of these kinases is altered in human diseases, particularly cancer.

The development of gene therapy: from monogenic recessive disorders to complex diseases such as cancer

During the last 4 decades, gene therapy has moved from preclinical to clinical studies for many diseases ranging from monogenic recessive disorders such as hemophilia to more complex diseases such as cancer, cardiovascular disorders, and human immunodeficiency virus (HIV). To date, more than 1,340 gene therapy clinical trials have been completed, are ongoing, or have been approved in 28 countries, using more than 100 genes. Most of those clinical trials (66.5%) were aimed at the treatment of cancer. Early hype, failures, and tragic events have now largely been replaced by the necessary stepwise progress needed to realize clinical benefits. We now understand better the strengths and weaknesses of various gene transfer vectors; this facilitates the choice of appropriate vectors for individual diseases. Continuous advances in our understanding of tumor biology have allowed the development of elegant, more efficient, and less toxic treatment strategies. In this introductory chapter, we review the history of gene therapy since the early 1960s and present in detail two major recurring themes in gene therapy: (1) the development of vector and delivery systems and (2) the design of strategies to fight or cure particular diseases. The field of cancer gene therapy experienced an "awkward adolescence." Although this field has certainly not yet reached maturity, it still holds the potential of alleviating the suffering of many individuals with cancer.

In vivo evaluation of intravesical paclitaxel and combined bcl-xL antisense oligodeoxynucleotide treatment for orthotopic urothelial carcinoma

PURPOSE

To evaluate intravesical paclitaxel monotherapy and combined treatment with antiapoptotic bcl-xL antisense oligodeoxynucleotides (AS-ODNs) on urothelial carcinoma (UC).

METHODS

Forty-eight FoxN(rnu) athymic nude rats with orthotopic human bladder UC were randomized to four treatment groups [1, paclitaxel; 2, paclitaxel/bcl-xL AS-ODNs; 3, bcl-xL AS-ODNs (control); 4, medium (control)]. Three consecutive instillations were applied and weekly endoscopic tumor size measurements were performed.

RESULTS

Significant tumor size reduction was achieved in groups 1 and 2 (each P < 0.0001), whereas continuous UC growth was observed in control animals (groups 3 and 4; P < 0.0001 and P < 0.0020). Complete tumor eradication was achieved in four treated animals (groups 1 and 2). No significant difference in chemoresection effects was found between groups 1 and 2 (P = 0.2251).

CONCLUSIONS

We present an in vivo evaluation of intravesical treatment with paclitaxel and combined bcl-xL AS-ODNs. Despite efficient tumor size reduction, no gain was observed when adding bcl-xL AS-ODNs in this experimental setting.

Inhalable siRNA: potential as a therapeutic agent in the lungs

RNA interference (RNAi) is gaining increasing popularity both as a molecular biology tool and as a potential therapeutic agent. RNAi is a naturally occurring gene regulatory mechanism, which has a number of advantages over other gene/antisense therapies including specificity of inhibition, potency, the small size of the molecules and the diminished risk of toxic effects, e.g., immune responses. Targeted, local delivery of RNAi to the lungs via inhalation offers a unique opportunity to treat a range of previously untreatable or poorly controlled respiratory conditions. In this timely review we look at the potential applications of RNAi in the lungs for the treatment of a range of diseases including inflammatory and immune conditions, cystic fibrosis, infectious disease and cancer. In 2006 Alnylam initiated the first phase 1 clinical study of an inhaled siRNA for the treatment of respiratory syncytial virus. If its potential as a therapeutic is to be realized, then safe and efficient means of targeted delivery of small interfering RNA (siRNA) to the lungs must be developed. Therefore in this review we also present the latest developments in siRNA delivery to airway cells in vitro and the work to date on in vivo delivery of siRNA to the lungs for the treatment of a range of diseases.

A novel approach for the construction of multiple shRNA expression vectors

The application of RNA interference (RNAi) as a research and therapeutic tool depends on its ability to silence genes in a sequence-specific manner. Recent studies have reported that the effective knockdown of genes can be achieved by multiple short hairpin RNAs (shRNAs) in a single vector. Moreover, this approach can depress several genes simultaneously. However, current methods for the construction of multiple shRNA vectors often suffer from vector instability and are time-consuming. Here, we describe a simple, quick and low-cost approach to construct a single vector expressing four shRNA sequences driven by four different promoters. Using this vector, we were able to improve the gene silencing efficiency and make it possible to silence four different genes simultaneously, further expanding the application spectrum of RNAi, both in functional studies and therapeutic strategies.

Exploring the role of HIF-1 in early angiogenesis and response to radiotherapy

The objective of this review is to examine the role that HIF-1 plays in the initiation of angiogenesis and in radiotherapy response. Although these two phenomena may at first seem unrelated, there are parallelisms to be drawn associated with the importance of reactive oxygen species in controlling the transcriptional activity of HIF-1, independently of its main driving force, hypoxia. Knowledge of the mechanisms underlying the control of HIF-1 leads to rationale for its inhibition in a range of clinical scenarios.

Multiple effects of 2ME2 and D609 on the cortical expression of HIF-1alpha and apoptotic genes in a middle cerebral artery occlusion-induced focal ischemia rat model

Despite 2-methoxyestradiol (2ME2) and tricyclodecan-9-yl-xanthogenate (D609) having multiple effects on cancer cells, mechanistically, both of them down-regulate hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). We hypothesize HIF-1alpha plays an essential role in cerebral ischemia as a pro-apoptosis regulator; 2ME2 and D609 decrease the levels of HIF-1alpha and VEGF, that might contribute to protecting brain from ischemia injury. A total of 102 male Sprague-Dawley rats were split into five groups: sham, middle cerebral artery occlusion (MCAO), MCAO + dimethyl sulfoxide, MCAO + 2ME2, and MCAO + D609. 2ME2 and D609 were injected intraperitoneally 1 h after reperfusion. Rats were killed at 24 h and 7 days. At 24 h, 2ME2 and D609 reduce the levels of HIF-1alpha and VEGF (enzyme-linked immunosorbent assay), depress the expression of HIF-1alpha, VEGF, BCL2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3) and cleaved caspase 3 (western blot and immunohistochemistry) in the brain infarct area. Double fluorescence labeling shows HIF-1alpha positive immunoreactive materials are co-localized with BNIP3 and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling inside the nuclei of neurons. At 7 days, 2ME2 and D609 reduce the infarct volume (2,3,7-triphenyltetrazolium chloride) and blood-brain barrier extravasation, decrease the mortality and improve the neurological deficits. In conclusion, 2ME2 and D609 are powerful agents to protect brain from cerebral ischemic injury by inhibiting HIF-1alpha expression, attenuating the superfluous expression of VEGF to avoid blood-brain barrier disruption and suppressing neuronal apoptosis via BNIP3 pathway.

Exploring in vitro roles of siRNA in cardiovascular disease

RNA interference (RNAi) is an adaptive defense mechanism through which double stranded RNAs silence cognate genes in a sequence-specific manner. It has been employed widely as a powerful tool in functional genomics studies, target validation and therapeutic product development. Similarly, the application of small interfering RNA (siRNA) to the silencing of the disease-causing genes involved in cardiovascular diseases has made great progress. In this overview, we attempt to provide a brief outline of the current understanding of the mechanism of RNAi and its potential application to the cardiovascular system, with particular emphasis on its ability to identify the pathophysiological function of genes related to several important cardiovascular disorders. The prospects of RNAi-based therapeutics, as well as the advantages and potential problems, are also discussed.

EGFR-mediated expression of aquaporin-3 is involved in human skin fibroblast migration

AQP3 (aquaporin-3), known as an integral membrane channel in epidermal keratinocytes, facilitates water and glycerol movement into and out of the skin. Here, we demonstrate that AQP3 is also expressed in cultured human skin fibroblasts, which under normal wound healing processes migrate from surrounding tissues to close the wound. EGF (epidermal growth factor), which induced fibroblast migration, also induced AQP3 expression in a time- and dose-dependent manner. CuSO4 and NiCl2, previously known as AQP3 water transport inhibitors, as well as two other bivalent heavy metals Mn2+ and Co2+, inhibited EGF-induced cell migration in human skin fibroblasts. AQP3 knockdown by small interfering RNA inhibited EGF-induced AQP3 expression and cell migration. Furthermore, an EGFR (EGF receptor) kinase inhibitor, PD153035, blocked EGF-induced AQP3 expression and cell migration. MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase]/ERK inhibitor U0126 and PI3K (phosphoinositide 3-kinase) inhibitor LY294002 also inhibited EGF-induced AQP3 expression and cell migration. Collectively, our findings show for the first time that AQP3 is expressed in human skin fibroblasts and that EGF induces AQP3 expression via EGFR, PI3K and ERK signal transduction pathways. We have provided evidence for a novel role of AQP3 in human skin fibroblast cell migration, which occurs during normal wound healing.

Elucidating the role of protein kinase C in chronic lymphocytic leukaemia

While advances have been made in the clinical treatment of chronic lymphocytic leukaemia (CLL) in recent years, it is still an incurable disease and therefore the identification of novel drug therapies is of paramount importance. Understanding the molecular mechanisms that govern the survival of CLL cells is fundamental in achieving this goal. A number of studies indicate that protein kinase C (PKC)- and phosphatidylinositol-3-kinase (PI3K)- mediated signalling pathways are central to CLL cell survival, and as such PKC has gained renewed interest as a potential drug target in CLL. This may be because it represents a closely-related family of ten protein kinases, which due to the redundancy that exists between isoforms offers an opportunity for the design of isoform specific inhibitors drugs that target leukaemic cells whilst showing reduced toxicity for normal cells. Indeed, PKC signalling pathways have already been considered as targets for specific anticancer drugs [1-3]. Therefore, this short review will focus on the effect of modulating PKC activity in CLL cells and explore whether targeting PKCs could represent a valid therapy for this leukaemia.

The future of antisense oligonucleotides in the treatment of respiratory diseases

Antisense oligonucleotides (ASO) are short synthetic DNA molecules designed to inhibit translation of a targeted gene to protein via interaction with messenger RNA. More recently, small interfering (si)RNA have been developed as potent tools to specifically inhibit gene expression. ASO directed against signaling molecules, cytokine receptors, and transcription factors involved in allergic immune and inflammatory responses, have been applied in experimental models of asthma and demonstrate potential as therapeutics. Several ASO-based drugs directed against oncogenes have been developed for therapy of lung cancer, and some have recently reached clinical trials. ASO and siRNA to respiratory syncytial virus infection have demonstrated good potential to treat this condition, particularly in combination with an antiviral drug. Although ASO-based therapeutics are promising for lung diseases, issues of specificity, identification of correct molecular targets, delivery and carrier systems, as well as potential adverse effects must be carefully evaluated before clinical application.

Prospects of RNA interference therapy for cancer

RNA interference (RNAi) is a powerful gene-silencing process that holds great promise in the field of cancer therapy. The discovery of RNAi has generated enthusiasm within the scientific community, not only because it has been used to rapidly identify key molecules involved in many disease processes including cancer, but also because RNAi has the potential to be translated into a technology with major therapeutic applications. Our evolving understanding of the molecular pathways important for carcinogenesis has created opportunities for cancer therapy employing RNAi technology to target the key molecules within these pathways. Many gene products involved in carcinogenesis have already been explored as targets for RNAi intervention, and RNAi targeting of molecules crucial for tumor-host interactions and tumor resistance to chemo- or radiotherapy has also been investigated. In most of these studies, the silencing of critical gene products by RNAi technology has generated significant antiproliferative and/or proapoptotic effects in cell-culture systems or in preclinical animal models. Nevertheless, significant obstacles, such as in vivo delivery, incomplete suppression of target genes, nonspecific immune responses and the so-called off-target effects, need to be overcome before this technology can be successfully translated into the clinical arena. Significant progress has already been made in addressing some of these issues, and it is foreseen that early phase clinical trials will be initiated in the very near future.

Targeted molecular therapy of the PI3K pathway: therapeutic significance of PI3K subunit targeting in colorectal carcinoma

OBJECTIVE

The phosphatidylinositol 3-kinase (PI3K) pathway promotes cancer cell proliferation and survival. The authors determined the pattern of distribution of PI3K pathway components (ie, the p85alpha regulatory subunit, p110alpha catalytic subunit, Akt1, Akt2, and the tumor suppressor PTEN) in human colorectal cancer. In addition, inhibition of in vitro proliferation and in vivo liver metastasis by p85alpha or p110alpha siRNA treatment was analyzed.

SUMMARY BACKGROUND DATA

Small interfering RNA (siRNA) molecules suppress expression of target genes and may have therapeutic applications as target-specific therapies for cancer. Therefore, the purpose of this study was 2-fold: 1) to analyze the distribution pattern of PI3K pathway components in human normal colorectal cancers, and 2) to determine whether targeted inhibition of PI3K inhibits colon cancer growth in vitro and suppresses metastatic growth in vivo.

METHODS

Immunohistochemical analysis was performed on colorectal adenocarcinomas and adjacent normal mucosa for PI3K pathway components, including p85alpha, p110alpha, Akt1, Akt2, and the tumor suppressor PTEN, which inhibits PI3K. HT29 and KM20 human colon cancer cells were treated with siRNA directed to p85alpha or p110alpha, and cell viability and apoptosis assessed. HT29 cells, transfected with a plasmid containing green fluorescent protein (GFP), were injected into the spleen of athymic nude mice to establish liver metastases; mice were randomized to receive either nontargeting control (NTC), p85alpha or p110alpha siRNA.

RESULTS

PI3K pathway components p85alpha and Akt2 were highly expressed in glandular elements of colon cancers, with a correlation between staining intensity and clinical stage; PTEN expression was decreased in the colon cancers of all stages. PI3K-specific siRNA treatment decreased cell viability in vitro and suppressed metastatic tumor growth in vivo.

CONCLUSIONS

Selective targeting of PI3K pathway components may enhance the effects of standard chemotherapeutic agents and provide novel adjuvant treatment of selected colorectal cancers.

PKC eta as a therapeutic target in glioblastoma multiforme

Gliomas are the most common major subgroup of primary CNS tumours. Approximately 17,000 new cases are reported each year and, of these, 11,500 patients die. Glioblastoma multiforme (GBM) is highly proliferative and typically invades distal portions of the brain, thereby making complete surgical resection of these tumours nearly impossible. Moreover, GBMs are often resistant to current chemotherapy and radiation regimens. Therefore, there is a need for better therapeutic interventions. One class of proteins that is involved in the formation of malignant brain tumours is protein kinase C (PKC) and these kinases have not been thoroughly explored for their chemotherapeutic value in GBMs. The PKC isozyme, PKCeta (PKC-eta) increases cell proliferation and resistance to radiation of GBM cell lines. These properties make PKCeta an attractive target for chemotherapeutic intervention in the management of GBMs.

Subversion of protein kinase C alpha signaling in hematopoietic progenitor cells results in the generation of a B-cell chronic lymphocytic leukemia-like population in vivo

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived mature B cells with the distinctive phenotype CD19(hi) CD5+ CD23+ IgM(lo), which are refractory to apoptosis. An increased level of apoptosis has been observed on treatment of human B-CLL cells with protein kinase C (PKC) inhibitors, suggesting that this family of protein kinases mediate survival signals within B-CLL cells. Therefore, to investigate the ability of individual PKC isoforms to transform developing B cells, we stably expressed plasmids encoding PKC mutants in fetal liver-derived hematopoietic progenitor cells (HPC) from wild-type mice and then cultured them in B-cell generation systems in vitro and in vivo. Surprisingly, we noted that expression of a plasmid-encoding dominant-negative PKC alpha (PKC alpha-KR) in HPCs and subsequent culture both in vitro and in vivo resulted in the generation of a population of cells that displayed an enhanced proliferative capacity over untransfected cells and phenotypically resemble human B-CLL cells. In the absence of growth factors and stroma, these B-CLL-like cells undergo cell cycle arrest and, consistent with their ability to escape growth factor withdrawal-induced apoptosis, exhibited elevated levels of Bcl-2 expression. These studies therefore identify a unique oncogenic trigger for the development of a B-CLL-like disease resulting from the subversion of PKC alpha signaling. Our findings uncover novel avenues not only for the study of the induction of leukemic B cells but also for the development of therapeutic drugs to combat PKC alpha-regulated transformation events.

siRNA-based approaches in cancer therapy

The availability of the human genome sequence has revolutionized the strategy of employing nucleic acids with sequences complementary to specific target genes to improve drug discovery and target validation. Development of sequence-specific DNA or RNA analogs that can block the activity of selected single-stranded genetic sequences offers the possibility of rational design with high specificity, lacking in many current drug treatments for various diseases including cancer, at relatively inexpensive costs. Antisense technology is one such example that has shown promising results and boasts of yielding the only approved drug to date in the genomics field. However, in vivo delivery issues have yet to be completely overcome for widespread clinical applications. In contrast to antisense oligonucleotides, the mechanism of silencing an endogenous gene by the introduction of a homologous double-stranded RNA (dsRNA), transgene or virus is called post-transcriptional gene silencing (PTGS) or RNA interference. PTGS is a natural mechanism whereby metazoan cells suppress expansion of genes when they come across dsRNA molecules with the same sequence. Short interfering RNA is currently the fastest growing sector of this antigene field for target validation and therapeutic applications. Although, in theory, the development of genomics-based agents to inhibit gene expression is simple and straightforward, the fundamental concern relies upon the capacity of the oligonucleotide to gain access to the target RNA. This paper summarizes the advances in the last decade in the field of PTGS using RNA interference approaches and provides relevant comparisons with other oligonucleotide-based approaches with a specific focus on oncology applications.

Progress in the development of nucleic acid therapeutics

Abnormal gene expression is a hallmark of many diseases. Gene-specific downregulation of aberrant genes could be useful therapeutically and potentially less toxic than conventional therapies due its specificity. Over the years, many strategies have been proposed for silencing gene expression in a gene-specific manner. Three major approaches are antisense oligonucleotides (AS-ONs), ribozymes/DNAzymes, and RNA interference (RNAi). In this brief review, we will discuss the successes and shortcomings of these three gene-silencing methods, and the approaches being taken to improve the effectiveness of antisense molecules. We will also provide an overview of some of the clinical applications of antisense therapy.

Individualised cancer therapeutics: dream or reality?

Traditional measures for treating metastatic cancer involve identification of the originating organ from which the neoplasm arose and empirical treatment with cytotoxic chemotherapy. Arguably, with the exception of haematological malignancies, demonstration of efficacy in solid tumours has been limited. Over the past half-decade, theoretical and technological advances have resulted in greater application of molecular science to drug design, which has enabled development of new 'targeted' therapeutics. However, generic chemotherapy paradigms have not changed. Establishment of the optimal population for 'targeted' therapeutics based on molecular diagnostics (i.e. genomic and proteomic characterisation) to identify sensitive tumour-host ecosystems in individual patients at the 'bedside', is not being done as part of routine oncology management. This review focuses on the concept of designing individualised therapeutics based on genomic and proteomic profile of malignant tissue. Genetic and epigenetic perturbations in signal pathways drive cancer growth, survival, invasion and metastatic spread. The burgeoning evidence which supports the concept that each patient's cancer has a unique complement of pathogenic genetic and molecular derangements is reviewed. Such evidence supports the strategy of individualised selection of a therapeutic complex from a menu of targeting options that best complements the specific oncomolecular profile of the 'tumour-host' system.

Modulation of angiogenesis with siRNA inhibitors for novel therapeutics

Cancer and many other serious diseases are characterized by the uncontrolled growth of new blood vessels. Recently, RNA interference (RNAi) has reinvigorated the therapeutic prospects for inhibiting gene expression and promises many advantages over binding inhibitors, including high specificity, which is essential for targeted therapeutics. This article describes the latest developments using small-interfering RNA (siRNA) inhibitors to downregulate various angiogenic and tumor-associated factors, both in cell-culture assays and in animal disease models. The majority of research efforts are currently focused on understanding gene function, as well as proof-of-concept for siRNA-mediated anti-angiogenesis. The prospects for siRNA therapeutics, both advantages and looming hurdles, are evaluated.

Silencing of Bcl-XL expression in human MGC-803 gastric cancer cells by siRNA

To investigate the inhibitory effect of the Bcl-XL small interfering RNA (siRNA) on Bcl-XL gene expression in the human gastric cancer cell line MGC-803, green fluorescent protein (GFP) siRNA was constructed and transfected into MGC-803 cells, together with GFP expression vector pTrace SV40. GFP expression levels were observed using fluorescence microscopy. Bcl-XL siRNA and negative siRNA were then constructed and stably transfected into MGC-803 cells. RT-PCR and immunofluorescence were used to detect the expression of Bcl-XL. Spontaneous apoptosis was detected by acridine orange (AO) and flow cytometry. Results were as follows: (1) 48 h after GFP expression vector and GFP siRNA co-transfection, the expression level of GFP in the GFP siRNA group was much lower than the negative siRNA group, according to fluorescence microscopy results. The mRNA and protein levels of Bcl-XL in Bcl-XL siRNA stable transfectants were reduced to almost background level compared with negative siRNA transfectants or untreated cells. (2) Changes in nucleus morphology was observed by AO staining nucleic and flow cytometry analysis, which showed that stable Bcl-XL siRNA transfectants have an increased spontaneous apoptosis (21.17%+/-1.26% vs. 1.19%+/-0.18% and 1.56%+/-0.15% respectively, P < 0.05 vs. negative siRNA or untreated control). siRNA targeting GFP or Bcl-XL genes can specifically suppress GFP or Bcl-XL expression in MGC-803 cells, and Bcl-XL siRNA can increase spontaneous apoptosis. Bcl-XL siRNA may be a beneficial agent against human gastric adenocarcinoma.

The link between PKCalpha regulation and cellular transformation

Protein kinase Calpha (PKCalpha) is a serine/threonine protein kinase that has been implicated in the regulation of a variety of cellular functions such as proliferation, differentiation and apoptosis in response to a diverse range of stimuli. In order to execute these biological events PKCalpha activity is modulated by, and functionally interacts with, a number of proto-oncogenes, therefore it is perhaps unsurprising that dysregulation of PKCalpha is associated with a diverse range of cancers. Recently, PKCalpha has become a target for a number of anti-cancer therapies. The purpose of this review is to describe how PKCalpha regulates key biological events, to gain an insight into how PKCalpha-mediated cellular transformation may occur. In this way, it may be possible to design therapeutic tools to combat cancers specifically associated with PKCalpha dysfunction.

RNAi, a new therapeutic strategy against viral infection

RNA interference (RNAi) is an adaptive defense mechanism triggered by double-stranded RNA (dsRNA). It is a powerful reverse genetic tool that has been widely employed to silence gene expression in mammalian and human cells. RNAi-based gene therapies, especially in viral diseases have become more and more interesting and promising. Recently, small interfering RNA (siRNA) can be used to protect host from viral infection, inhibit the expression of viral antigen and accessory genes, control the transcription and replication of viral genome, hinder the assembly of viral particles, and display influences in virus-host interactions. In this review, we attempt to present recent progresses of this breakthrough technology in the above fields and summarize the possibilities of siRNA-based drugs.