Short interfering RNAs as a tool for cancer gene therapy

Silencing of cyclooxygenase-2 inhibits the growth, invasion and migration of ovarian cancer cells

The present study aimed to investigate the effect of downregulating cyclooxygenase‑2 (COX‑2) expression on the growth of human ovarian cancer cells. The COX‑2‑specific small interfering RNA (siRNA) plasmid vector was constructed and then transfected into ovarian cancer cells. The expression of COX‑2 mRNA and protein was detected by quantitative polymerase chain reaction and western blot analysis, respectively. Cell proliferation, apoptosis, cell cycle distribution and cell migration were assessed following knockdown of COX‑2 by RNA interference (RNAi). Western blot analysis was used to identify differentially expressed angiogenesis- and cell cycle‑associated proteins in cells with silenced COX‑2. The expression levels of COX‑2 in ovarian cancer cells transfected with siRNA were decreased, leading to a significant inhibition of ovarian cancer cell proliferation, migration and invasion. Western blot analysis revealed that silencing of COX‑2 may inhibit vascular endothelial growth factor, matrix metalloproteinase (MMP)‑2 and MMP‑9 protein expression. In conclusion, the present study demonstrated that RNAi can effectively silence COX‑2 gene expression and inhibit the growth of ovarian cancer cells, which indicates that there is a potential of targeting COX‑2 as a novel gene therapy approach for the treatment of ovarian cancer.

Lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of nasopharyngeal carcinoma cell line C666-1 in vitro

Latent membrane protein 2A (LMP2A) is found to play a key role in the development of nasopharyngeal carcinoma (NPC). However, the role of LMP2A silencing in the inhibition of cell growth of NPC has not been clarified. In this study, we inhibited LMP2A gene expression by lentivirus-mediated RNAi, to explore the effects of LMP2A silencing on the growth of NPC cell line in vitro. A lentivirus-mediated RNAi technology was employed to specifically knock down the LMP2A gene in NPC cell line C666-1. Quantitative real-time polymerase chain reaction, Western blot, flow cytometry and colony formation assays were performed to evaluate the expression of LMP2A and biological behavior of cell line C666-1 in vitro. We successfully construct a highly efficient and stable lentivirus vector, which efficiently downregulate the expression of LMP2A gene in infected cell line C666-1. Down-regulation of the expression of LMP2A significantly inhibits the proliferation and colony formation of C666-1 cells. In addition, the specific down-regulation of LMP2A arrests cells in G0/G1 phase of cell cycle and increases apoptosis rate. Our findings suggest that lentivirus-mediated RNAi knockdown of LMP2A inhibits the growth of NPC cell line C666-1 in vitro, and LMP2A may be a potential target for gene therapy in treatment of NPC.

Silencing neurodegenerative disease: bringing RNA interference to the clinic

RNA interference (RNAi) is a recently described conserved biological pathway where non-coding RNAs suppress the expression of specific genes. Research efforts in the RNAi field aim to gain a better understanding of how its underlying machinery is orchestrated, to define the biological role of this conserved pathway, determine how to effectively manipulate RNAi in the laboratory and to integrate all this knowledge to develop novel therapies for human disease. This review summarizes the advances in the design of therapeutic RNAi for neurodegenerative diseases and discusses some of the experimental steps required to bring this therapy to human clinical trials.

Chitosan nanoparticle carrying small interfering RNA to platelet-derived growth factor B mRNA inhibits proliferation of smooth muscle cells in rabbit injured arteries

The purpose of this study was to elucidate the transfection of chitosan nanoparticle carrying small interfering RNA against platelet-derived growth factor B (PDGF-B) to inhibit the expression of PDGF-B mRNA and proliferation of smooth muscle cells. A rabbit iliac artery injury model was constructed. A small interfering RNA (siRNA) against PDGF-B mRNA expression vector was constructed and packaged by chitosan nanoparticle to transfect into the vascular smooth muscle cells (vSMCs) of balloon catheter-injured rabbit iliac artery wall, using a therapeutic ultrasound for the gene delivery. The experiment was divided into two groups: experimental group, denudation and nano-PDGF-B siRNA treated, and only single denudation as control. Effects of the siRNA on the expressions of proliferating cell nuclear antigen (PCNA) and PDGF-B mRNA by vSMCs and the proliferation of vSMCs were observed with the methods of routine pathological, immunohistochemical staining, in situ hybridization and morphometry. The nano siRNA against PDGF-B was successfully transfected. The nano siRNA significantly inhibited the expressions of PCNA and PDGF-B mRNA in intimal vSMCs. The local intimal thickness and area were also reduced remarkably. In conclusion, transfection of chitosan nanoparticle carrying siRNA against PDGF-B mRNA could inhibit proliferation of vSMCs in the rabbit iliac artery injury model.

Recent advances in delivery of drug-nucleic acid combinations for cancer treatment

Cancer treatment that uses a combination of approaches with the ability to affect multiple disease pathways has been proven highly effective in the treatment of many cancers. Combination therapy can include multiple chemotherapeutics or combinations of chemotherapeutics with other treatment modalities like surgery or radiation. However, despite the widespread clinical use of combination therapies, relatively little attention has been given to the potential of modern nanocarrier delivery methods, like liposomes, micelles, and nanoparticles, to enhance the efficacy of combination treatments. This lack of knowledge is particularly notable in the limited success of vectors for the delivery of combinations of nucleic acids with traditional small molecule drugs. The delivery of drug-nucleic acid combinations is particularly challenging due to differences in the physicochemical properties of the two types of agents. This review discusses recent advances in the development of delivery methods using combinations of small molecule drugs and nucleic acid therapeutics to treat cancer. This review primarily focuses on the rationale used for selecting appropriate drug-nucleic acid combinations as well as progress in the development of nanocarriers suitable for simultaneous delivery of drug-nucleic acid combinations.

Current translational and clinical practices in hematopoietic cell and gene therapy

Clinical trials over the last 15 years have demonstrated that cell and gene therapies for cancer, monogenic and infectious disease are feasible and can lead to long-term benefit for patients. However, these trials have been limited to proof-of-principle and were conducted on modest numbers of patients or over long periods of time. In order for these studies to move towards standard practice and commercialization, scalable technologies for the isolation, ex vivo manipulation and delivery of these cells to patients must be developed. Additionally, regulatory strategies and clinical protocols for the collection, creation and delivery of cell products must be generated. In this article we review recent progress in hematopoietic cell and gene therapy, describe some of the current issues facing the field and discuss clinical, technical and regulatory approaches used to navigate the road to product development.

Protein-resistant, reductively dissociable polyplexes for in vivo systemic delivery and tumor-targeting of siRNA

Small interfering RNA (siRNA) has been considered as a very attractive therapeutic alternative to chemical drugs; however, the chemical and biological instability and poor delivery efficiency of siRNA limit its success in clinical applications. Here we report a protein-resistant, reductively dissociable siRNA delivery system based on self-assembled polyelectrolyte complexes of dextran-siRNA conjugates linked by disulfide bonds. The prepared polyplexes exhibit excellent dispersion stability in the presence of serum because of the anti-fouling property of dextran exposed onto the complex surface. The enzymatic degradation of siRNA is also effectively suppressed within the complex. Folates are introduced as an active tumor-targeting moiety via the conjugation of folates to the hydroxyl groups of dextran. An in vivo investigation with a xenograft tumor mouse model shows that the folate-decorated dextran-siRNA conjugates are very efficiently targeted to cancer cells and induce sequence-specific gene silencing.

Selective cell death of p53-insufficient cancer cells is induced by knockdown of the mRNA export molecule GANP

Cancer cells often contain p53 abnormalities that impair cell-cycle checkpoint progression and cause resistance to various anti-cancer treatments. DNA damage occurs at actively transcribed genes during G1-phase in yeast cells that have a deficient mRNA export capacity. Here, we show that germinal center-associated nuclear protein (GANP), a homologue of yeast Sac3 that is involved in mRNA export, is indispensable for ensuring the stability of human genomic DNA and that GANP knockdown causes apoptosis and necrosis of p53-insufficient cancer cells. Ganp small interfering RNA (siGanp)-induced DNA damage, accompanied by a decrease in the number of cells in S-phase, caused late apoptosis and necrosis in p53-insufficient cancer cells through both caspase-dependent and -independent mechanisms. siGanp effectively induced DNA damage leading to cell death in p53-insufficient cancer cells in vitro and protect the growth of cancer cells transplanted into immunocompromized mice, suggesting that siGanp has potential as a selective treatment for p53-insufficient cancer cells.

Bmi1 gene silencing inhibits the proliferation and invasiveness of human hepatocellular carcinoma cells and increases their sensitivity to 5-fluorouracil

The Bmi1 gene has been reported to play important roles in cancer initiation and progression. The aim of this study was to investigate the effects of RNA interference (RNAi)-mediated silencing of Bmi1 gene expression on the proliferation and invasiveness of hepatocellular carcinoma (HCC) cells and on the efficacy of chemotherapy in HCC patients. The Bmi1 gene was silenced by Bmi1-siRNA (small interfering RNA) in the human HCC cell lines HepG2 and Bel-7402, and the gene expression levels were assayed by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting. The proliferation and migration of Bmi1-silenced tumor cells and their sensitivity to 5-FU treatment were determined by Cell Counting Kit-8 (CCK-8), transwell assays and 4',6-diamidino-2-phenylindole (DAPI) staining and flow cytometry, respectively. Bmi1-siRNA inhibited the Bmi1 expression at both the mRNA and protein levels in HCC cells. Proliferation and migration of HCC cells treated with Bmi1-siRNA was significantly lower compared to that of the control cells. Moreover, Bmi1 gene silencing increased the percentage of apoptotic cells treated by 5-FU and decreased the IC50 values of 5-FU to a greater extent. Downregulation of the Bmi1 gene by RNAi can inhibit the proliferation and invasivesness of HCC cells and increase their sensitivity to 5-FU treatment.

Tyroserleutide-based gene vector for suppressing VEGF expression in cancer therapy

A small interfering RNA (siRNA) plasmid DNA (pYr-1.1-hU6-EGFP-siVEGF) was constructed and used for suppressing vascular endothelial growth factor (VEGF) expression and inhibiting tumor growth. Then, a (tyrosyl-seryl-leucine)-polyethyleneimine-poly(ethylene glycol) (YSL-PEI-PEG) conjugate was designed and synthesized as a gene carrier for the delivery of pYr-1.1-hU6-EGFP-siVEGF plasmid. The therapeutic peptide YSL was conjugated to PEI to improve the anti-cancer efficiency, and the PEG chain was introduced to reduce the serum protein adsorption and improve the stability of the complex in the systemic circulation. It was found that YSL-PEI-PEG could efficiently condense plasmid DNA when the vector/DNA weight ratio was higher than 2. Compared with PEI 25 kDa, YSL-PEI-PEG exhibited higher transfection efficiency and lower cytotoxicity. More importantly, the results showed that the gene delivery system owned strong ability to inhibit cancer cell proliferation in vitro and tumor growth in vivo. YSL-PEI-PEG has great potential as a gene vector for clinical applications.

Small RNAs targeting transcription start site induce heparanase silencing through interference with transcription initiation in human cancer cells

Heparanase (HPA), an endo-h-D-glucuronidase that cleaves the heparan sulfate chain of heparan sulfate proteoglycans, is overexpressed in majority of human cancers. Recent evidence suggests that small interfering RNA (siRNA) induces transcriptional gene silencing (TGS) in human cells. In this study, transfection of siRNA against −9/+10 bp (siH3), but not −174/−155 bp (siH1) or −134/−115 bp (siH2) region relative to transcription start site (TSS) locating at 101 bp upstream of the translation start site, resulted in TGS of heparanase in human prostate cancer, bladder cancer, and gastric cancer cells in a sequence-specific manner. Methylation-specific PCR and bisulfite sequencing revealed no DNA methylation of CpG islands within heparanase promoter in siH3-transfected cells. The TGS of heparanase did not involve changes of epigenetic markers histone H3 lysine 9 dimethylation (H3K9me2), histone H3 lysine 27 trimethylation (H3K27me3) or active chromatin marker acetylated histone H3 (AcH3). The regulation of alternative splicing was not involved in siH3-mediated TGS. Instead, siH3 interfered with transcription initiation via decreasing the binding of both RNA polymerase II and transcription factor II B (TFIIB), but not the binding of transcription factors Sp1 or early growth response 1, on the heparanase promoter. Moreover, Argonaute 1 and Argonaute 2 facilitated the decreased binding of RNA polymerase II and TFIIB on heparanase promoter, and were necessary in siH3-induced TGS of heparanase. Stable transfection of the short hairpin RNA construct targeting heparanase TSS (−9/+10 bp) into cancer cells, resulted in decreased proliferation, invasion, metastasis and angiogenesis of cancer cells in vitro and in athymic mice models. These results suggest that small RNAs targeting TSS can induce TGS of heparanase via interference with transcription initiation, and significantly suppress the tumor growth, invasion, metastasis and angiogenesis of cancer cells.

Silence of p15 expression by RNAi enhances cisplatin resistance in hepatocellular carcinoma cells

The insensitivity of hepatocellular carcinoma to chemotherapy is associated with alternation in tumor cell cycling. This current study was designed to investigate the impact of p15 silencing on the sensitivity of Human hepatocellular carcinoma HepG2 cells to cisplatin. HepG2/CDDP/1.6 and HepG2/CDDP/2.0 cells were induced by culture with increased doses of cisplatin and their sensitivities to cis-Diamine dichloroplatinum (CDDP) were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The impacts of p15 silencing on the cell cycling and P-gp expression were characterized by flow cytometry, RT-PCR and Western blot assays, respectively. Knockdown of p15 expression dramatically reduced the relative levels of p15 expression and the frequency of phase G1, promoting cell cycling. On the other hand, knockdown of p15 expression significantly up-regulated the expression of P-glycoprotein (P-gp) in HepG2/CDDP/2.0 cells, associated with the increased resistance of HepG2 cells to CDDP in vitro. In conclusion, the p15 may be a critical regulator of the development of CDDP resistance in HepG2 cells.

Effects of RNAi-mediated matrix metalloproteinase-2 gene silencing on the invasiveness and adhesion of esophageal carcinoma cells, KYSE150

BACKGROUND

Esophageal carcinoma is one of the main malignancies in China. Previous studies indicated that matrix metalloproteinases (MMPs) play important roles in the process of tumor invasion and metastasis in several types of solid tumors. Among all of the MMPs, MMP-2 is one of the MMPs closely associated with tumor invasion. In this study, we suppressed MMP-2 expression with RNA interference and then observed inhibitory effects on the invasion and migration of the esophageal carcinoma cell line KYSE150.

METHODS

Three target sequences were selected and siRNA against MMP-2 mRNA were synthesized. After being transfected by the transfection complexes, the MMP-2 expression of KYSE150 cells, which overexpresses MMP-2, were examined by Western blot analysis and real-time polymerase chain reaction (PCR). Cell migration and invasion were measured with migration assay and Boyden chamber assays, respectively.

RESULTS

RNAi against MMP-2 successfully inhibited the mRNA and protein expression of MMP-2 in the esophageal carcinoma cell line KYSE150. MMP-2 knockdown inhibited the invasion and migration of esophageal carcinoma cell line KYSE150.

CONCLUSIONS

These findings suggested that the RNAi approach towards MMP-2 may be a potentially effective therapeutic method for the treatment of esophageal carcinoma.

Targeted silencing of heparanase gene by small interfering RNA inhibits invasiveness and metastasis of osteosarcoma cells

The effects of targeted silencing of heparanase gene by small interfering RNA (siRNA) on invasiveness and metastasis of osteosarcoma cells (MG63 cells) were investigated in the present study. Two complementary oligonucleotide strands were synthesized and inserted into pGenesil-1 vector based on the mRNA sequence of heparanase gene. The expression vector containing short hairpin RNA (pGenesil-shRNA) was constructed successfully. MG63 cells were randomly allocated into 3 groups: blank group, empty vector (pGenesil) transfected group and expression vector (pGenesil-shRNA) transfected group. Under the induction of Lipofectamine 2000, the recombinants were transfected into MG63 cells. Heparanase gene expression level was detected by RT-PCR and Western blotting. Cell proliferation was measured by MTT assay. Cell invasiveness and metastasis were examined by cell adhesion and Transwell-ECM assays. HUVECs migration assay was applied for the detection of angiogenesis. As compared with negative controls, the mRNA and protein expression levels of heparanase were down-regulated by 76.1% (P<0.01) and 75.3% (P<0.01) respectively in the pGenesil-shRNA transfected group. Meanwhile, the proliferation, adhesiveness, invasiveness and angiogenesis properties of MG63 cells were all significantly inhibited. It was suggested that targeted silencing of heparanase gene by siRNA could dramatically inhibit the invasiveness and metastasis of osteosarcoma cells.

RNAi-mediated downregulation of NOB1 suppresses the growth and colony-formation ability of human ovarian cancer cells

Nin one binding protein (NOB1p), encoded by the NOB1 gene, is a crucial molecule in the maturation of the 20S proteasome and protein degradation. The present study evaluates whether NOB1 is an appropriate molecular target for cancer gene therapy. In two ovarian cancer cell lines, SKOV3 and HEY, NOB1 expression was knocked down by a lentiviral short hairpin RNA (shRNA) delivery system. The RNA interference (RNAi)-mediated the downregulation of NOB1 expression markedly reduced the proliferative and colony-formation ability of ovarian cancer cells. Additionally, NOB1 shRNA-expressing lentivirus-treated ovarian cancer cells tended to arrest in the G0/G1 phase. These results suggested that NOB1 may act as an oncogenic factor in ovarian cancer and could be a potential molecular target for ovarian cancer gene therapy.

Is survivin the potential Achilles' heel of cancer?

Survivin, the smallest member of the inhibitors of apoptosis proteins (IAPs), plays an important role in the control of apoptosis, cell division, and cell migration/metastasis. Survivin is expressed and required for normal fetal development but is then generally no longer present in most adult tissues. However, reexpression of survivin is observed in numerous human cancers where presence of the protein is associated with enhanced proliferation, metastasis, poor prognosis, and decreased patient survival. Given the relatively selective expression in cancer cells, but not in normal tissue (tumor-associated antigen), and its importance in tumor cell biology, survivin has emerged as an attractive target for cancer treatment. Here, we discuss some aspects of survivin biology by focusing on why the protein appears to be so important for cancer cells and then discuss strategies that harness this dependence to eradicate tumors and situate survivin as a potential Achilles' heel of cancer.

Small RNA interference-mediated gene silencing of heparanase abolishes the invasion, metastasis and angiogenesis of gastric cancer cells

Background

Heparanase facilitates the invasion and metastasis of cancer cells, and is over-expressed in many kinds of malignancies. Our studies indicated that heparanase was frequently expressed in advanced gastric cancers. The aim of this study is to determine whether silencing of heparanase expression can abolish the malignant characteristics of gastric cancer cells.

Methods

Three heparanase-specific small interfering RNA (siRNAs) were designed, synthesized, and transfected into cultured gastric cancer cell line SGC-7901. Heparanase expression was measured by RT-PCR, real-time quantitative PCR and Western blot. Cell proliferation was detected by MTT colorimetry and colony formation assay. The in vitro invasion and metastasis of cancer cells were measured by cell adhesion assay, scratch assay and matrigel invasion assay. The angiogenesis capabilities of cancer cells were measured by tube formation of endothelial cells.

Results

Transfection of siRNA against 1496-1514 bp of encoding regions resulted in reduced expression of heparanase, which started at 24 hrs and lasted for 120 hrs post-transfection. The siRNA-mediated silencing of heparanase suppressed the cellular proliferation of SGC-7901 cells. In addition, the in vitro invasion and metastasis of cancer cells were attenuated after knock-down of heparanase. Moreover, transfection of heparanase-specific siRNA attenuated the in vitro angiogenesis of cancer cells in a dose-dependent manner.

Conclusions

These results demonstrated that gene silencing of heparanase can efficiently abolish the proliferation, invasion, metastasis and angiogenesis of human gastric cancer cells in vitro, suggesting that heparanase-specific siRNA is of potential values as a novel therapeutic agent for human gastric cancer.

Effectiveness of microRNA in Down-regulation of TGF-beta gene expression in digital flexor tendons of chickens: in vitro and in vivo study

PURPOSE

Transforming growth factor (TGF)-beta is considered to be responsible for the formation of scars such as adhesions around healing digital flexor tendons. We proposed to deliver microRNAs (miRNAs) to silence expression of the TGF-beta1 gene and to investigate the effectiveness of miRNAs in down-regulation of the TGF-beta1 gene in vitro and in vivo.

METHODS

We designed and engineered 4 miRNAs according to genetic sequences of chicken TGF-beta1. Four plasmid vectors harboring the respective engineered miRNAs and 1 control vector were constructed. We transfected 30 wells of cultured tenocytes with these vectors and harvested them 48 hours later. The gene expression levels were quantified using real-time polymerase chain reactions. Subsequently, the miRNA that most effectively silenced TGF-beta gene in vitro was tested on 25 chickens in vivo. The miRNA and control vectors were injected into the injured tendons, respectively. At 1 and 6 weeks after surgery, the tendons were analyzed for gene expression and protein production.

RESULTS

In both in vitro and in vivo settings, delivery of miRNA to the tendon substantially down-regulated expression of the TGF-beta gene but did not affect expression of the collagen I gene. In the healing tendon, TGF-beta gene expression was significantly down-regulated by 50% to 60% at 1 and 6 weeks. At 6 weeks, the collagen III gene expression was significantly down-regulated by 55% at 6 weeks and the connective tissue growth factor gene was significantly down-regulated by 25%. At 6 weeks, TGF-beta protein was substantially decreased.

CONCLUSIONS

MicroRNA significantly down-regulates expression of the TGF-beta in vitro and in vivo. Application of miRNA did not down-regulate expression of the collagen I, but downregulated the collagen III gene. Application of miRNA treatment to modulate TGF-beta expression holds great promise in preventing tendon adhesion formation.

Survivin and its spliced isoform gene expression is associated with proliferation of renal cancer cells and clinical stage of renal cancer

BACKGROUND

Survivin has been implicated in inhibition of apoptosis. To date, alternatively spliced isoforms, Survivin-2alpha, -2B, -DeltaEx3, -3B, have been described. We assessed the effect of survivin gene expression on the proliferation of renal cancer (RCC) cells, and studied the association of survivin and its spliced isoform gene expression levels with the clinical stage of RCC.

METHODS

Gene expression of survivin and its spliced isoform in RCC cells, Caki-1, were performed by RT-PCR. We knocked down the gene expression of Survivin using small interfering RNA (siRNA), and assessed the cell proliferation by MTS assay. Next, we quantified the gene expression levels of survivin and its isoform in nephrectomy samples using quantitative real-time PCR.

RESULTS

In Caki-1 cells, survivin and survivin-2alpha, -2B were expressed higher than survivin-DeltaEx3. Decrease of Survivin gene expression by transfection of siRNA was accompanied by inhibition of the proliferation of Caki-1 cell with 36% decrease in comparison with negative control transfected cells (p<0.01). In clinical RCC tissues, survivin expression levels in metastatic stage were significantly higher compared with those in distant metastasis stage (M0:M1=1:4.81, p=0.014); survivin 2B gene expression levels in pT3 tumors were associated significantly higher than those in pT1 (pT1:pT3=1:4.50, p=0.043). No significant differences were found in survivin-2alpha expression levels and the ratio of survivin-2B/survivin gene expression levels among any clinical stages.

CONCLUSION

We first demonstrated the gene expression of survivin-2alpha in renal cancer cells, and also showed that survivin and its spliced isoforms had associations with renal cancer cell proliferation and distant metastases.

Lentivirus-mediated small interfering RNA targeting VEGF-C inhibited tumor lymphangiogenesis and growth in breast carcinoma

Lymph node metastasis is a major prognostic factor for patients with breast cancer. The activation of vascular endothelial growth factor (VEGF)-C plays a key role in lymph node metastasis through promoting lymphangiogenesis. Thus, we attempted to elucidate whether small interfering RNAs (siRNA) targeting VEGF-C could suppress lymphangiogenesis and lymph node metastasis in vivo. A lentivirus-based VEGF-C siRNA vector was infected into breast cancer cells and a xenograft model. The expression of VEGF-C mRNA and protein were quantified by quantitative real-time polymerase chain reaction (QRT-PCR), immunohistochemistry, and western blot analysis. The effect of VEGF-C siRNA on breast cancer cells was investigated by an invasion assay. Lymphangiogenesis was analyzed with anti-LYVE-1 and anti-D2-40 by immunohistochemical analysis. Lentivirus-mediated VEGF-C siRNA stably reduced VEGF-C mRNA and protein expression. VEGF-C siRNA inhibited the invasive ability of breast cancer cells in vitro. Five weeks after intratumoral injection, the tumor volume was significantly smaller in the VEGF-C siRNA group than in the control scramble siRNA group in the MDA-MB-231 cell xenograft model. The numbers of LYVE-1 and D2-40 positive vessels per microscopic field were significantly decreased in the VEGF-C siRNA group, which indicates that VEGF-C siRNA inhibited lymphangiogenesis. Moreover, lymph node metastasis was significantly suppressed by VEGF-C siRNA in vivo. In conclusion, these results indicate that lentivirus-mediated VEGF-C siRNA offers a new approach for therapeutic intervention to prevent tumor growth and lymphatic metastasis of breast cancer.

Gene expression of survivin and its spliced isoforms associated with proliferation and aggressive phenotypes of prostate cancer

OBJECTIVES

To assess the effect of survivin gene expression on the proliferation of prostate cancer (PCa) cells and study the association of suvivin and its spliced isoforms gene expression levels with the pathologic grade of PCa.

METHODS

Gene expression of survivin and its spliced isoforms in the LNCaP and PC-3 PCa cell lines was determined using reverse transcriptase-polymerase chain reaction. We knocked down the gene expression of survivin using small interfering RNA and assessed the cell proliferation using the MTS assay. Next, we quantified the gene expression levels of survivin and its isoforms in prostate biopsy samples (PCa, n = 37; benign prostatic hyperplasia, n = 13; PCa after androgen deprivation therapy, n = 12) using the quantitative real-time polymerase chain reaction method.

RESULTS

In PCa cells, survivin and survivin-2alpha and survivin-2B were expressed more than survivin-DeltaEx3. The decrease in survivin gene expression by transfection of siRNA was accompanied by the inhibition of cell proliferation of PCa cells (31% and 25% decreased in LNCaP and PC-3 cells, P <0.01). In the prostate biopsy samples, the survivin expression in PCa was significantly greater than that in BPH or PCa after androgen deprivation therapy (PCa, 1; BPH, 0.16; PCa after androgen deprivation therapy, 0.27; P <0.01). In the PCa samples, the survivin expression level was associated significantly with high-grade cancer (Gleason score 8 or 9; Gleason score 7 versus 8 or 9, 1 versus 2.00, respectively; P <0.05). The survivin-2B/survivin ratio in high-grade cancer was lower than that in low-grade (Gleason score 7) cancer (Gleason score 7 versus 8 or 9, 1 versus 0.69; P <0.10).

CONCLUSIONS

These findings suggest that survivin and its spliced isoforms have associations with PCa cell proliferation and aggressive phenotypes.

Modulation of drug resistance by artificial transcription factors

The efficiency of chemotherapeutic treatments in cancer patients is often impaired by the acquisition of drug resistance. Cancer cells develop drug resistance through dysregulation of one or more genes or cellular pathways. To isolate efficient regulators of drug resistance in tumor cells, we have adopted a genome-wide scanning approach based on the screening of large libraries of artificial transcription factors (ATFs) made of three and six randomly assembled zinc finger domains. Zinc finger libraries were linked to a VP64 activation domain and delivered into a paclitaxel-sensitive tumor cell line. Following drug treatment, several ATFs were isolated that promoted drug resistance. One of these ATFs, 3ZF-1-VP, promoted paclitaxel resistance in cell lines having mutated or inactivated p53, such as MDA-MB-435 and Kaposi's sarcoma cell lines. 3ZF-1-VP also induced strong resistance to etoposide, vincristine, and cisplatinum. Linkage of a repression domain to the selected ATF resulted in enhanced sensitivity to multiple drugs, particularly vincristine, cisplatinum, and 5-fluorouracil. Small interfering RNA-mediated inhibition of p53 revealed that 3ZF-1-VP activated both p53-dependent and p53-independent mechanisms to promote survival, whereas other ATF required intact p53. Real-time expression analysis and DNA microarrays showed that several ATFs up-regulated targets of p53, such as the cyclin-dependent kinase inhibitor p21(WAF1/CIP1), and genes participating in the p14(ARF)-MDM2-p53 tumor suppressor pathway, such as hDMP1. Thus, ATF can be used to map genes and pathways involved in drug resistance phenotypes and have potential as novel therapeutic agents to inhibit drug resistance.

Silencing livin gene by siRNA leads to apoptosis induction, cell cycle arrest, and proliferation inhibition in malignant melanoma LiBr cells

AIM

The aim of the present study was to investigate the effects of silencing the livin gene by small interfering RNA (siRNA) on the expression of livin and the effects on apoptosis, cell cycle, and proliferation in human malignant melanoma LiBr cells.

METHODS

Three chemically-synthetic siRNA duplexes targeting livin were transiently transfected into the LiBr cells, and the effects on livin expression were detected both at the mRNA level by real-time RT-PCR and at the protein level by Western blotting. Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling assay, flow cytometric analysis, and the expression of procaspase-3 and activated caspase-3 analysis by Western blotting. Cell cycle was analyzed by flow cytometry. Cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.

RESULTS

One of the 3 designed siRNA could effectively knock down the livin expression both at the mRNA and protein levels in dose- and time-dependent manners; 100 nmol/L with maximum downregulation on mRNA at 48 h, and on the protein at 72 h after transfection. Silencing livin could significantly induce apoptosis, arrest cell cycle at the G0/G1 phase, and inhibit proliferation in LiBr cells. Meanwhile, caspase-3 was activated.

CONCLUSION

The livin gene could serve as a potential molecular target for gene therapy by siRNA for malignant melanoma.

Technology insight: therapeutic RNA interference--how far from the neurology clinic?

As an evolutionarily conserved cellular pathway to regulate endogenous gene expression, RNA interference (RNAi) has been implicated in diverse biological processes. Biologists now routinely exploit this cellular pathway to suppress virtually any target gene in a sequence-specific manner, including dominantly acting genes that cause incurable neurodegenerative disorders. The development of RNAi as potential therapy for such diseases has generated considerable interest, partly because of the success of early studies of therapeutic RNAi in rodent models for a range of neurodegenerative diseases. In this article, we review the progress of RNAi therapy to date, and assess the challenges ahead for the application of such therapy to neurodegenerative diseases. We discuss the various strategies that might be used to achieve this goal, outline the preclinical studies that have already been completed, and highlight the experimental questions that need to be answered before human clinical trials can begin.

Taxanes, microtubules and chemoresistant breast cancer

The taxanes, paclitaxel and docetaxel are microtubule-stabilizing agents that function primarily by interfering with spindle microtubule dynamics causing cell cycle arrest and apoptosis. However, the mechanisms underlying their action have yet to be fully elucidated. These agents have become widely recognized as active chemotherapeutic agents in the treatment of metastatic breast cancer and early-stage breast cancer with benefits gained in terms of overall survival (OS) and disease-free survival (DFS). However, even with response to taxane treatment the time to progression (TTP) is relatively short, prolonging life for a matter of months, with studies showing that patients treated with taxanes eventually relapse. This review focuses on chemoresistance to taxane treatment particularly in relation to the spindle assembly checkpoint (SAC) and dysfunctional regulation of apoptotic signaling. Since spindle microtubules are the primary drug targets for taxanes, important SAC proteins such as MAD2, BUBR1, Synuclein-gamma and Aurora A have emerged as potentially important predictive markers of taxane resistance, as have specific checkpoint proteins such as BRCA1. Moreover, overexpression of the drug efflux pump MDR-1/P-gp, altered expression of microtubule-associated proteins (MAPs) including tau, stathmin and MAP4 may help to identify those patients who are most at risk of recurrence and those patients most likely to benefit from taxane treatment.

Suppression of human colon cancer tumors in nude mice by siRNA CD44 gene therapy

The expression of CD44, an adhesion protein associated with the tumor stem cell phenotype, is increased in most human malignant neoplasms. To further delineate the role of CD44 in colon cancer, we inhibited its expression using the siRNA method. HT-29, a human colon cancer cell line producing a large amount of CD44, was transfected with a construct producing a siRNA targeting a 19 mer sequence of the transmembrane domain of CD44 spanning between exon 16 and 17. Following stable transfection, siRNA CD44 resulted in over 75% inhibition of CD44 expression. The stable lines were less adhesive to hyaluronan and more susceptible to apoptosis induced by etoposide. siRNA CD44 clones formed a lower number and size of colonies in soft agar assays. A siRNA CD44 cell clone xenografted in nude mice generated tumors with a reduced tumor volume and wet weight, as compared to control vector clone. Intratumoral gene therapy with a polyethylenimine/siRNA CD44 plasmid DNA complex resulted in tumor growth suppression in nude mice. After siRNA CD44 intratumoral gene therapy, apoptosis was increased in the tumors when compared to the control vector group. In conclusion, based on this mouse xenograft model, siRNA targeting a discrete sequence of human CD44 may provide a potential therapeutic option for colon cancer.

Gene silencing of TKTL1 by RNAi inhibits cell proliferation in human hepatoma cells

We detected a strong upregulation of the mutated transketolase transcript (TKTL1) in human hepatoma cell line HepG2, whereas transketolase (TKT) and transketolase-like-2 (TKTL2) transcripts were not upregulated. We inhibited the expression of TKTL1 by RNAi in HepG2 cells. It was found that total transketolase activity was dramatically downregulated and the proliferation of cancer cells was significantly inhibited in HepG2 cells. These results indicate that TKTL1 gene influences total transketolase activity and cell proliferation in human hepatoma cells, suggesting that TKTL1 gene plays an important role on glycometabolism in tumors and it might become a novel target for tumor gene therapy.

Computational design of an RNA hexagonal nanoring and an RNA nanotube

The combination of computer modeling, RNA structure versatility, and siRNA function can be efficiently used to design an all-RNA nanoparticle capable of siRNA delivery. Here, we present a computational design of an RNA nanoring and a nanotube. An RNA nanoring consists of six simple linear building blocks that are assembled together via known noncovalent loop-loop contacts based on RNAI/RNAII inverse sequences. The helical sequences of the building blocks can include siRNAs for drug delivery.

RNAi-mediated knockdown of target genes: a promising strategy for pancreatic cancer research

Pancreatic cancer is one of the most aggressive malignancies with a very poor prognosis, partially due to its very low accessibility to resection and resistance to chemoradiotherapy. As such, it is reasonable to find more effective, specific therapies and the related therapeutic targets. The identification of certain genes contributing to the tumorigenesis and poor prognosis provides the specific targets for efficient silencing by RNA interference (RNAi). As a powerful tool to suppress gene expression in mammalian cells, RNAi can be directed against pancreatic cancer through various pathways, including the inhibition of overexpressed oncogenes, suppression of tumor growth, metastasis and enhancement of apoptosis. In combination with chemoradiotherapy agents, RNAi can also attenuate the chemoradiation resistance of pancreatic cancer. In addition, RNAi has been used to define the 'loss of function' of endogenous genes in pancreatic cancer. This review provides a brief introduction to recent developments of RNAi applications in pancreatic cancer studies and suggestions for further exploration. It substantially demonstrates that RNAi holds a promising therapeutic potential as a future treatment for pancreatic cancer.

Survivin: Potential role in diagnosis, prognosis and targeted therapy of gastric cancer

Survivin is a protein that is highly expressed in a vast number of malignancies, but is minimally expressed in normal tissues. It plays a role as an inhibitor of cell death in cancer cells, thus facilitating the growth of these cells. In the case of gastric cancer, survivin is over-expressed in tumor cells and plays a role in the carcinogenesis process. Several studies on gastric cancer have indicated that there is a relationship between survivin expression and the ultimate behavior of the carcinoma. Since the expression pattern of survivin is selective to cancer cells, it has been described as an “ideal target” for cancer therapy. Currently, several pre-clinical and clinical trials are on-going to investigate the effects of interfering with survivin function in cancer cells as a biologic therapy. Survivin is a potentially significant protein in the diagnosis, prognosis and treatment of gastric tumors.

Ribonucleic acid interference for neurological disorders: candidate diseases, potential targets, and current approaches

OBJECTIVE

Ribonucleic acid (RNA) interference (RNAi) is a conserved evolutionary defense mechanism that is gaining utility for therapeutic application by modulating gene expression or silencing disease-causing genes.

METHODS

This strategy has recently achieved success in mammalian cells via synthetic small interfering RNA or short hairpin RNA expressed in vectors for gene delivery. The vector-based RNAi strategy has particular potential because of the possibility of targeted gene delivery, long-term gene expression, and the potential means of penetrating the blood-brain barrier.

RESULTS

RNAi-based approaches have been proposed for a variety of neurological disorders, including dominant genetic diseases, neurodegenerative diseases, malignant brain tumors, pain, and viral-induced encephalopathies.

CONCLUSION

This review summarizes the current approaches of the RNAi strategy for neurological disorders, focusing on potential targets for therapeutic intervention.

Combination Silencer RNA (siRNA) Targeting Bcl-2 Antagonizes siRNA against Thymidylate Synthase in Human Tumor Cell Lines

Nonspecific toxicity and resistance to traditional cytotoxic drugs are impediments to effective cancer therapy. Development of drugs targeting cellular molecules that mediate malignant characteristics may improve therapy. Antisense drugs that reduce mRNA and protein on which tumor cells depend for viability and treatment resistance are examples of such candidates. In particular, combining antisense drugs to simultaneously reduce multiple mRNAs/proteins is predicted to enhance antitumor effects. We hypothesized that combined treatment with silencer RNAs (siRNAs) targeting molecules mediating both proliferation (thymidylate synthase; TS) and survival (Bcl-2) would decrease proliferation and sensitize human tumor cells to nonantisense drugs in a greater-than-additive manner. We report that simultaneous treatment of human cervical carcinoma (HeLa) and breast tumor (MCF-7) cell lines with siRNAs targeting both TS and Bcl-2 had unexpected, nonreciprocal antagonistic effects. Two siRNAs targeting different Bcl-2 mRNA sequences reduced the capacity of TS siRNA to reduce TS mRNA and protein, with no evidence of converse effects by TS siRNA on Bcl-2 mRNA or protein. Moreover, treatment of HeLa cells with siRNA targeting Bcl-2 resulted in increased TS mRNA and protein. Pretreatment of HeLa and MCF-7 cells with TS siRNA sensitized cells to TS-targeting drugs, but addition of antagonistic Bcl-2 siRNA to the pretreatment regimen abrogated sensitization. Combined targeting of separate physiological pathways by antisense reagents may be a useful approach in treatment of cancer, but antagonistic interactions could abrogate advantages or reduce effectiveness of other antisense and nonantisense reagents.

Downregulation of survivin by RNAi inhibits growth of human gastric carcinoma cells

AIM: To investigate the inhibitory effect of a specific small survivin interfering RNA (siRNA) on cell proliferation and the expression of survivin in human gastric carcinoma cell line SGC-7901.

METHODS: To knockdown survivin expression, a small interfering RNA targeting against survivin was synthesized and transfected into SGC-7901 cells with lipofectamine^TM2000. The downregulation of survivin expression at both mRNA and protein levels were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. Cell proliferation inhibition rates were determined by methyl thiazolyl tetrazolium (MTT) assay. The effect of survivin siRNA on cell cycle distribution and cell apoptosis was determined by flow cytometry (FCM).

RESULTS: RNA interference could efficiently suppress the survivin expression in SGC-7901 cells. At 48 h after transfection, the expression inhibition rate was 44.52% at mRNA level detected by RT-PCR and 40.17% at protein level by Western blot analysis. Downregulation of survivin resulted in significant inhibition of tumor cell growth in vitro. The cell proliferation inhibition rates at 24, 48 and 72 h after survivin siRNA and non-siliencing siRNA transfection, were 34.06%, 47.61% and 40.36%, respectively. The apoptosis rate was 3.56% and the number of cells was increased in G₀/G₁ phase from 38.2% to 88.6%, and decreased in S and G₂/M phase at 48 h after transfection.

CONCLUSION: Downregulation of survivin results in significant inhibition of tumor growth in vitro. The inhibition of survivin expression can induce apoptosis of SGC-7901 cells. The use of survivin siRNA deserves further investigation as a novel approach to cancer therapy.

Anaplastic lymphoma kinase and its signalling molecules as novel targets in lymphoma therapy

A crucial issue in the development of molecularly-targeted anticancer therapies is the identification of appropriate molecules whose targeting would result in tumour regression with a minimal level of systemic toxicity. Anaplastic lymphoma kinase (ALK) is a transmembrane receptor tyrosine kinase, normally expressed at low levels in the nervous system. As a consequence of chromosomal translocations involving the alk gene (2p23), ALK is also aberrantly expressed and constitutively activated in approximately 60% of CD30+ anaplastic large cell lymphomas (ALCLs). Due to the selective overexpression of ALK in tumour cells, its direct involvement in the process of malignant transformation and its frequent expression in ALCL patients, the authors recognise ALK as a suitable candidate for the development of molecularly targeted strategies for the therapeutic treatment of ALK-positive lymphomas. Strategies targeting ALK directly or indirectly via the inhibition of the protein networks responsible for ALK oncogenic signalling are discussed.

RNA interference: implications for cancer treatment

RNA interference (RNAi) has emerged as one of the most important discoveries of the last years in the field of molecular biology. Following clarification of this highly conserved endogenous gene silencing mechanism, RNAi has largely been exploited as a powerful tool to uncover the function of specific genes and to understand the effects of selective gene silencing in mammalian cells both in vitro and in vivo. RNAi can be induced by direct introduction of chemically synthesized siRNAs into the cell or by the use of plasmid and viral vectors encoding for siRNA allowing a more stable RNA knockdown. Potential application of this technique both as a research tool and for therapeutic purposes has led to an extensive effort to overcome some critical constraints which may limit its successful application in vivo, including off-target and non-specific effects, as well as the relatively poor stability of siRNA. This review provides a brief overview of the RNAi mechanism and of its application in preclinical animal models of cancer.

Livin/ML-IAP as a new target for cancer treatment

Livin is a member of the inhibitors of apoptosis protein (IAP) gene family, which encodes negative regulatory proteins that prevent cell apoptosis. Livin is selectively expressed in the most common human neoplasms and appears to be involved in tumor cell resistance to chemotherapeutic agents. Several studies in vitro and in vivo have demonstrated that down-regulation of Livin expression increases the apoptotic rate, reduces tumor growth potential and sensitized tumor cells to chemotherapeutic drugs. This review will focus on the role of this protein during cancer development and progression and will demonstrate possible targets for cancer therapy.

Enhancement of an electroporation system for gene delivery using electrophoresis with a planar electrode

In this paper a new electroporation (EP) system is developed, which includes an EP microchip and a logic circuit, which combined with electrophoresis (ES), can provide site-specific enhancement of gene concentration. In this ES-EP microchip, an arc planar electrode provides the ES function for DNA attraction, and interdigitated array electrodes provide appropriate electric fields for the EP on the chip surface. In addition, the adherent cells can be manipulated in situ without detachment of the ES-EP microchip, which performs the "Lab on a chip". Experimental results have shown that the efficiency of gene transfection with an attracting-electric field (35.89%) becomes much higher than that without an attracting-electric field (16.62%). Cell numbers as low as 10(4) cells, and DNA as little as 4 microg are sufficient for evaluating the phenotypic effects following the over-expression of the introduced genes on the ES-EP microchip. The proposed system has the advantages of portability, cost-effectiveness, a high transfection rate and ease of operation.

Survivin--an attractive target for RNAi in non-Hodgkin's lymphoma, Daudi cell line as a model

RNA interference (RNAi) has been widely used in tumor gene therapy, antivirus and gene drug selection. Survivin gene is highly expressed in non-Hodgkin's lymphoma (NHL) tissues and high malignancy Burkitt's lymphoma cell line-Daudi and it is regarded as a potential target of gene therapy for NHL. This study used a vector-based short hairpin RNA (shRNA) technique to explore the effect of RNAi-mediated survivin gene silencing on apoptosis and proliferation of Daudi cells. Recombinant plasmid survivin-shRNA was transfected into Daudi cells transiently and stably. The expression of survivin was detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The apoptosis of Daudi cells after transfection were evaluated by flow cytometry. After transfection of survivin-shRNA, the levels of survivin mRNA were significantly reduced by 64.20% (transient transfection) and 62.32% (stable transfection), respectively; The levels of survivin protein were significantly reduced by 63.50% (transient transfection) and 61.88% (stable transfection); compared with control-shRNA and PBS treated groups. Apoptosis of Daudi cells were significantly higher in the transfection group than in the control group, respectively 21.30 +/- 2.96% (transient transfection) and 19.10 +/- 2.15% (stable transfection). In conclusion, it was suggested that survivin could be an attractive target for new anti-cancer intervention of NHL and vector-based survivin-shRNA could effectively reduce the expression of survivin and induce cell apoptosis and growth inhibition of NHL cells.