Knockdown of survivin expression by small interfering RNA reduces the clonogenic survival of human sarcoma cell lines independently of p53

Immunoexpression of Survivin and P53 in the Histological Subtypes of Medulloblastoma: A Cross-Sectional Observational Study

Medulloblastoma (MB) is a common malignant intracranial neoplasms in children. The treatment and prognosis of this tumor depends on histology and molecular subtypes. Survivin, implicated in various malignancies, may hold prognostic significance. We investigated survivin and p53 immunoreactivity in different histological subtypes in 20 MB cases from January 2018 to June 2021. Immunohistochemistry revealed survivin expression in 75% (15/20) of cases, with cytoplasmic (10 cases), nuclear (four cases), or combined expression (one case). p53 nuclear expression was present in 35% (7/20) of cases. Classical variant MB exhibited predominant p53 and cytoplasmic survivin expression. Given the association of survivin and p53 expression with poor prognosis, especially in the prevalent classical variant, targeted therapies may hold promise for MB treatment advancement.

A Novel Recombinant Fcγ Receptor-Targeted Survivin Combines with Chemotherapy for Efficient Cancer Treatment

Formyl peptide receptor-like 1 inhibitor (FLIPr), an Fcγ receptor (FcγR) antagonist, can be used as a carrier to guide antigen-FLIPr fusion protein to FcγR then enhances antigen-specific immune responses. Survivin, a tumor-associated antigen, is over-expressed in various types of human cancer. In this study, we demonstrate that recombinant survivin-FLIPr fusion protein (rSur-FLIPr) binds to FcγRs, and efficient uptake by dendritic cells in vivo. In addition, rSur-FLIPr alone stimulates survivin-specific immune responses, which effectively suppresses the tumor growth. The antitumor immunities are through TAP-mediated and CD8-dependent pathways. Furthermore, preexisting anti-FLIPr antibody does not abolish antitumor responses induced by rSur-FLIPr immunization. These results suggest that FLIPr is an effective antigen delivery vector and can be repeatedly used. Combination of chemotherapy with rSur-FLIPr treatment reveals a great benefit to tumor-bearing mice. Altogether, these findings suggest that rSur-FLIPr is a potential candidate for efficient cancer therapy.

Modulation of a Stem Cell Gene: LGR4 Knockout in a Human Cell Line by CRISPR/Cas Method

The modulation of gene expression is essential for the investigation of function or involved pathway of a single gene of interest, in particular in the developmental/stem cell biology. The temporary knock down of gene expression via siRNA is a well-established but with a residual expression connected modulation method. The chapter describes the complete knockout of a defined target and allows a comprehensive study of different gene like the stem cell gene LGR4 (Leucine-rich repeat-containing G-protein-coupled receptor 4) using the new developed CRISPR/Cas method (clustered regularly interspaced short palindromic repeats).

Nucleic acids therapeutics using PolyPurine Reverse Hoogsteen hairpins

PolyPurine Reverse Hoogsteen hairpins (PPRHs) are DNA hairpins formed by intramolecular reverse Hoogsteen bonds which can bind to polypyrimidine stretches in dsDNA by Watson:Crick bonds, thus forming a triplex and displacing the fourth strand of the DNA complex. PPRHs were first described as a gene silencing tool in vitro for DHFR, telomerase and survivin genes. Then, the effect of PPRHs directed against the survivin gene was also determined in vivo using a xenograft model of prostate cancer cells (PC3). Since then, the ability of PPRHs to inhibit gene expression has been explored in other genes involved in cancer (BCL-2, mTOR, topoisomerase, C-MYC and MDM2), in immunotherapy (SIRPα/CD47 and PD-1/PD-L1 tandem) or in replication stress (WEE1 and CHK1). Furthermore, PPRHs have the ability to target the complementary strand of a G-quadruplex motif as a regulatory element of the TYMS gene. PPRHs have also the potential to correct point mutations in the DNA as shown in two collections of CHO cell lines bearing mutations in either the dhfr or aprt loci. Finally, based on the capability of PPRHs to form triplexes, they have been incorporated as probes in biosensors for the determination of the DNA methylation status of PAX-5 in cancer and the detection of mtLSU rRNA for the diagnosis of Pneumocystis jirovecii. Of note, PPRHs have high stability and do not present immunogenicity, hepatotoxicity or nephrotoxicity in vitro. Overall, PPRHs constitute a new economical biotechnological tool with multiple biomedical applications.

Cancer therapeutics using survivin BIRC5 as a target: what can we do after over two decades of study?

Survivin (also named BIRC5) is a well-known cancer therapeutic target. Since its discovery more than two decades ago, the use of survivin as a target for cancer therapeutics has remained a central goal of survivin studies in the cancer field. Many studies have provided intriguing insight into survivin's functional role in cancers, thus providing promise for survivin as a cancer therapeutic target. Despite this, moving survivin-targeting agents into and through the clinic remains a challenge. In order to address this challenge, we may need to rethink current strategies in order to develop a new mindset for targeting survivin. In this Review, we will first summarize the current survivin mechanistic studies, and then review the status of survivin cancer therapeutics, which is classified into five categories: (i) survivin-partner protein interaction inhibitors, (ii) survivin homodimerization inhibitors, (iii) survivin gene transcription inhibitors, (iv) survivin mRNA inhibitors and (v) survivin immunotherapy. We will then provide our opinions on cancer therapeutics using survivin as a target, with the goal of stimulating discussion that might facilitate translational research for discovering improved strategies and/or more effective anticancer agents that target survivin for cancer therapy.

Targeting mutant TP53 as a potential therapeutic strategy for the treatment of osteosarcoma

Mutant TP53 is a promising therapeutic target in cancers. Considering the current challenges facing the clinical treatment of cancer, as well as the urgent need to identify novel therapeutic targets in osteosarcomas, we aimed to evaluate the clinical significance of mutant TP53 in osteosarcoma patients and to explore the therapeutic effect of targeting mutant TP53 in osteosarcomas. We performed a meta-analysis to investigate the relationship between mutant TP53 and the overall survival of patients with osteosarcoma. A CRISPR-Cas9 system and a TP53 inhibitor, NSC59984, were also used to specifically knock-out and inhibit mutant TP53 in the human osteosarcoma cell lines, KHOS, and KHOSR2. The meta-analysis demonstrated that mutations in the TP53 gene could be used to predict a poor 2-year survival in osteosarcoma patients. We also demonstrated that the expression of mutant TP53 in human osteosarcoma cell lines can be efficiently knocked-out using CRISPR-Cas9, and this decreased the proliferation, migration, and tumor formation activity of these osteosarcoma cells. Moreover, drug sensitivity to doxorubicin was increased in these TP53 knock-out osteosarcoma cells. NSC59984 also showed similar anti-tumor effects as CRISPR-Cas9 targeted TP53 in the osteosarcoma cells in vitro. We have also demonstrated that the knock-out or inhibition of mutant TP53 decreased the expression of the oncogene IGF-1R, anti-apoptotic proteins Bcl-2, and Survivin in osteosarcoma cells. Collectively, these results suggest that mutant TP53 is a promising therapeutic target in osteosarcomas. Therefore, further studies exploring novel strategies to target mutant TP53 may help improve the treatment outcomes of osteosarcoma patients in the clinic. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Self-Transfecting Micellar RNA: Modulating Nanoparticle Cell Interactions via High Density Display of Small Molecule Ligands on Micelle Coronas

The intracellular delivery of synthetic nucleic acids represents a major challenge in biotechnology and in biomedicine. Methods to deliver short, double-stranded RNA to living cells are of particular interest because of the potential to engage the RNA interference machinery and to regulate mRNA expression. In this work, we describe novel RNA-polymer amphiphiles that assemble into spherical micellar nanoparticles with diameters of ca. 15-30 nm and efficiently enter live cells without transfection reagents. Each micelle consists of approximately 100 RNA strands forming a densely packed corona around a polymeric core. Importantly, the surface-displayed RNA remains accessible for hybridization with complementary RNA. Chemical modification of the termini of hybridized RNA strands enabled the display of small organic moieties on the outer surface of the micelle corona. We found that some of these modifications can have a tremendous impact on cellular internalization efficiencies. The display of hydrophobic dabcyl or stilbene units dramatically increased cell uptake, whereas hydrophilic neutral hydroxy or anionic phosphate residues were ineffective. Interestingly, neither of these modifications mediated noticeable uptake of free RNA oligonucleotides. We infer that their high density display on micellar nanoparticle surfaces is key for the observed effect; achieved with local effective surface concentrations in the millimolar range. We speculate that weak interactions with cell surface receptors that are amplified by the multivalent presentation of such modifications may be responsible. The installation of small molecule ligands on nanomaterial surfaces via hybridization of chemically modified oligonucleotides offers a simple and straightforward way to modulate cellular uptake of nanoparticles. Biological functionality of micellar RNA was demonstrated through the sequence-specific regulation of mRNA expression in HeLa cells.

YM155 induces apoptosis in p53-deficient T-acute lymphoblastic leukemia cells independent of survivin inhibition

T-acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer that arises from the malignant transformation of T-cell progenitors. Despite the significant progress in current treatment, challenges remain the lifelong morbidity after current chemotherapy regimens and postrelapse survival. In addition, patients with T-ALL have inferior outcomes compared with those with B-cell precursor; consequently, novel therapeutic approaches are still necessary to improve the outcome in this cohort. YM155 is an imidazolium derivative originally discovered as a suppressant of survivin expression. It has been reported that YM155 has potent antiproliferative activity on a variety of human cancer cell lines; however, its effects in T-ALL cells have been underexplored. The aim of the present study was to examine the effects of YM155 on p53-deficient T-ALL cell lines, JURKAT and CCRF-CEM. Resazurin dye was used to evaluate cell viability. Colony formation was observed in MethoCult methylcellulose medium. Apoptotic cells were detected by flow cytometry (annexin V labeling and TUNEL assay). Cell cycle analysis was carried out by DNA quantification in flow cytometry. DNA damage was assessed using a comet assay and the survivin expression profile was evaluated by real-time PCR and immunoblotting. YM155 treatment decreased cell viability and clonogenicity capacity of T-ALL cells, increased the apoptosis index and DNA damage, and altered the cell cycle dynamic, independent of survivin inhibition. Taken together, the data reinforce that YM155 may be useful as a therapeutic possibility to combat leukemia.

Expression and Therapeutic Potential of SOX9 in Chordoma

Purpose: Conventional chemotherapeutic agents are ineffective in the treatment of chordoma. We investigated the functional roles and therapeutic relevance of the sex-determining region Y (SRY)-box 9 (SOX9) in chordoma.Experimental Design: SOX9 expression was examined by immunohistochemistry (IHC) using 50 chordoma tissue samples. SOX9 expression in chordoma cell lines was examined by Western blot and immunofluorescent assays. We used synthetic human SOX9 siRNA to inhibit the expression of SOX9. Cell proliferation ability and cytotoxicity of inhibiting SOX9 were assessed by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) and clonogenic assays. The effect of SOX9 knockdown on chordoma cell motility was evaluated by a wound-healing assay and a Transwell invasion chamber assay. Knockdown of SOX9 induced apoptosis, cell-cycle arrest, as well as decreased expression of cancer stem cell markers were determined by Western blot and flow cytometric assays. The effect of the combination of SOX9 siRNA and the chemotherapeutic drug doxorubicin/cisplatin on chordoma cells was assessed by an MTT assay.Results: Tissue microarray and IHC analysis showed that SOX9 is broadly expressed in chordomas and that higher expression levels of SOX9 correlated with a poor prognosis. RNA interference (RNAi)-mediated knockdown of SOX9 inhibited chordoma cell growth, decreased cell motility, and induced apoptosis as well as cell-cycle arrest. Moreover, the combination of SOX9 inhibition and chemotherapeutic drugs had an enhanced anti-cancer effect on chordoma cells.Conclusions: Our results demonstrate that SOX9 plays a crucial role in chordoma. Targeting SOX9 provides a new rationale for treatment of chordoma. Clin Cancer Res; 23(17); 5176-86. ©2017 AACR.

Optimization of Ionic Liquid-Assisted Extraction of Biflavonoids from Selaginella doederleinii and Evaluation of Its Antioxidant and Antitumor Activity

As new green solvents, ionic liquids (ILs) have been generally applied in the extraction and separation of natural product. In this study, microwave assisted extraction based on IL (IL-MAE) was firstly employed to extract total biflavonoids from Selaginella doederleinii. Based on single-factor experiment, microwave power (300–700 W), extract time (30–50 min) and extract temperature (40–60 °C) on total bioflavonoids and antioxidant activities of the extracts were further investigated by a Box-Behnken design of response surface methodology (RSM) selecting total bioflavonoids yields and IC₅₀ of radical scavenging as index. Besides antioxidant activity of the extract was evaluated by a 2,2-diphenyl-1-picrylhydarzyl (DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging assay, ferric reducing power assay and chelation of ferrous ions assay, and then anticaner activity was also researched against A549 cell line and 7721 cell line. The results illustrated that three factors and their interactions could be well suited for second-order polynomial models (p < 0.05). Through process parameters, optimization of the extract (460 W, 40 min, and 45 °C) and detection of bioactivity, the yield of total bioflavonoids was 16.83 mg/g and IC₅₀ value was 56.24 μg/mL, respectively, indicating the extract has better anti-oxidation effect and antitumor activity. Furthermore, IL-MAE was the most efficient extracting method compared with MAE and Soxhlet extraction, which could improve extraction efficiency in a shorter time and at a lower temperature. In general, ILs-MAE was first adopted to establish a novel and green extraction process on the yields of total biflavonoids from S. doederleinii. In addition, the extract of containing biflavones showed potent antioxidant and anticancer capacity as a utilized valuable bioactive source for natural medicine.

Simultaneous cytosolic delivery of a chemotherapeutic and siRNA using nanoparticle-stabilized nanocapsules

We report on nanoparticle-stabilized capsules (NPSCs) as a platform for the co-delivery of survivin-targeted siRNA and tamoxifen. These capsules feature an inner oil core that provides a carrier for tamoxifen, and is coated on the surface with positively charged nanoparticles self-assembled with siRNA. The multifaceted chemical nature of the NPSC system enables the simultaneous delivery of both payloads directly into the cytosol in vitro. The NPSC co-delivery of tamoxifen and survivin-targeted siRNA into breast cancer cells disables the pathways that inhibit apoptosis, resulting in enhanced breast cell death.

Establishment and molecular characterisation of seven novel soft-tissue sarcoma cell lines

Background:

Soft-tissue sarcomas (STS) are a diverse group of malignancies that remain a diagnostic and therapeutic challenge. Relatively few reliable cell lines currently exist. Rapidly developing technology for genomic profiling with emerging insights into candidate functional (driver) aberrations raises the need for more models for in vitro functional validation of molecular targets.

Methods:

Primary cell culture was performed on STS tumours utilising a differential attachment approach. Cell lines were characterised by morphology, immunocytochemistry, proliferation assays, short tandem repeat (STR) and microarray-based genomic copy number profiling.

Results:

Of 47 STS cases of various subtypes, half formed adherent monolayers. Seven formed self-immortalised cell lines, including three undifferentiated pleomorphic sarcomas, two dedifferentiated liposarcomas (one of which had received radiotherapy), a leiomyosarcoma and a myxofibrosarcoma. Two morphologically distinct yet genetically identical variants were established in separate cultures for the latter two tumours. All cell lines demonstrated genomic and phenotypic features that not only confirm their malignant characteristics but also confirm retention of DNA copy number aberrations present in their parent tumours that likely include drivers.

Conclusions:

These primary cell lines are much-needed additions to the number of reliable cell lines of STS with complex genomics available for initial functional validation of candidate molecular targets.

Transarterial chemoembolization of hepatocellular carcinoma in a rat model: the effect of additional injection of survivin siRNA to the treatment protocol

BACKGROUND

Transarterial chemoembolization is one of the most widely accepted interventional treatment options for treatment of hepatocellular carcinoma. Still there is a lack of a standard protocol regarding the injected chemotherapeutics. Survivin is an inhibitor of Apoptosis protein that functions to inhibit apoptosis, promote proliferation, and enhance invasion. Survivin is selectively up-regulated in many human tumors. Small interfering RNA (siRNA) can trigger an RNA interference response in mammalian cells and induce strong inhibition of specific gene expression including Survivin. The aim of the study is to assess the effectiveness of the additional injection of Survivin siRNA to the routine protocol of Transarterial Chemoembolization (TACE) for the treatment of hepatocellular carcinoma in a rat model.

METHODS

The study was performed on 20 male ACI rats. On day 0 a solid Morris Hepatoma 3924A was subcapsullary implanted in the liver. On day 12 MRI measurement of the initial tumor volume (V1) was performed. TACE was performed on day 13. The rats were divided into 2 groups; Group (A, n = 10) in which 0.1 mg mitomycin, 0.1 ml lipiodol and 5.0 mg degradable starch microspheres were injected in addition 2.5 nmol survivin siRNA were injected. The same agents were injected in Group (B,=10) without Survivin siRNA. MRI was repeated on day 25 to assess the tumor volume (V2). The tumor growth ratio (V2/V1) was calculated. Western blot and immunohistochemical analysis were performed.

RESULTS

For group A the mean tumor growth ratio (V2/V1) was 1.1313 +/- 0.1381, and was 3.1911 +/- 0.1393 in group B. A statistically significant difference between both groups was observed regarding the inhibition of tumor growth (P < 0.0001) where Group A showed more inhibition compared to Group B. Similarly immunohistochemical analysis showed significantly lower (p < 0.002) VEGF staining in group A compared to group B. Western Blot analysis showed a similar difference in VEGF expression (P < 0.0001).

CONCLUSION

The additional injection of Survivin siRNA to the routine TACE protocol increased the inhibition of the hepatocellular carcinoma growth in a rat animal model compared to regular TACE protocol.

Normoxic accumulation of HIF1α is associated with glutaminolysis

OBJECTIVES

The stabilization of the transcription factor and prognostic tumor marker hypoxia-inducible factor 1α (HIF1α) is considered to be crucial for cellular metabolic adaptations to hypoxia. However, HIF1α has also been shown to accumulate under normoxic conditions, although this phenomenon is poorly understood.

METHODS

We investigated the conditions for normoxic HIF1α stabilization in different tumor cell lines (e.g., two mammary carcinoma cell lines and three oral squamous cell carcinoma cell lines) via Western blot analysis or immunohistochemical staining. The transcriptional activity of HIF1 was demonstrated by analyzing the messenger RNA (mRNA) expression of the HIF1 target carbonic anhydrase 9 (CA9) via PCR.

RESULTS

Our data demonstrate that the combined incubation of tumor cells with glutamine and growth factors (e.g., EGF, insulin, and serum) mediates the normoxic accumulation of HIF1α in vitro. Consequently, the inhibition of glutaminolysis by a glutaminase inhibitor blocked the normoxic accumulation of HIF1α. Additionally, the normoxic HIF1α protein displayed nuclear translocation and transcriptional activity, which was confirmed by the induction of CA9 mRNA expression. Furthermore, the normoxic accumulation of HIF1α was associated with impaired proliferation of tumor cells. Finally, ammonia, the toxic waste product of glutaminolysis, induced a normoxic accumulation of HIF1α to the same extent as glutamine.

CONCLUSION

Our study suggests that HIF1α is involved in the regulation of glutamine metabolism and the cellular levels of the toxic metabolic waste product ammonia under normoxia. Hence, our results, together with data presented in the literature, support the hypothesis that HIF1α and its target genes play a crucial role in metabolic pathways, such as glutaminolysis and glycolysis, under both hypoxic and normoxic conditions.

CLINICAL RELEVANCE

Therefore, the inhibition of HIF1α (and/or HIF1α target genes) could emerge as a promising therapeutic approach that would result in the accumulation of toxic metabolic waste products in tumor cells as well as the reduction of their nutrition and energy supply.

Methanolic Extract of Pien Tze Huang Induces Apoptosis Signaling in Human Osteosarcoma MG63 Cells via Multiple Pathways

Pien Tze Huang (PZH) is a well-known traditional Chinese formulation and has long been used as an alternative remedy for cancers in China and Southeast Asia. Recently, antitumor activity of PZH on several tumors have been increasingly reported, but its antitumor activity and the possible action mechanism on osteosarcoma remains unclear. After treatment with PZH, cell viability of MG-63 cells was dose-dependently inhibited compared to control cells. Moreover, a DNA ladder characteristic of apoptosis was observed in the cells treated with PZH, especially 500 μg/mL, 750 μg/mL. Further investigation showed that PZH treatments led to activation of caspase cascades and changes of apoptotic mediators Bcl2, Bax, and Bcl-xL expression. In addition, our results suggested that PZH activated PI3K/Akt signal pathway, and the phosphorylation of Akt and ERK1/2 were associated with the induction of apoptotic signaling. These results revealed that PZH possesses antitumoral activity on human osteosarcoma MG63 cells by manipulating apoptotic signaling and multiple pathways. It is suggested that PZH alone or combined with regular antitumor drugs may be beneficial as osteosarcoma treatments.

Growth inhibition and chemo-radiosensitization of head and neck squamous cell carcinoma (HNSCC) by survivin-siRNA lentivirus

BACKGROUND

Survivin expression is often associated with aggressive tumor behavior and therapy resistance. In this study, we investigated the effect of survivin knockdown by survivin-siRNA lentiviral vector (Svv-Lent) on the response of HNSCC to chemo-radiotherapy, tumor growth and metastasis.

METHODS

Four human HNSCC (OSC19, Cal27, Cal33 and FaDu) and one normal HOK cell lines were included in the study, and survivin knockdown was achieved with Svv-Lent treatment. Cell proliferation and apoptosis were measured by MTT and TUNEL assay, respectively. Transwell assays were performed to measure in vitro cell migration and matrigel invasion. Xenograft tumors were developed in nude mice by injecting Cal27 cells subcutaneously and following tail-vein injection of lung and liver metastasis.

RESULTS

Knockdown of survivin significantly suppressed HNSCC cell proliferation and induced apoptosis in vitro. Survivin inhibition could also significantly reduce in vitro cell migration and matrigel invasion that might be due to inactivation of matrix metalloproteinases. In vivo studies showed significant repression of Cal27 xenograft tumor growth and tissue metastasis leading to improvement in mice survival in the Svv-Lent treated group compared to controls. Our data indicated that survivin expression in HNSCC cells contributed to chemo-radioresistance, and its down-regulation increased anti-cancer effects of paclitaxel, cisplatin and radiation.

CONCLUSIONS

Our findings suggest that sustained survivin expression facilitates HNSCC tumor growth and confers resistance to chemo-radiotherapy. Svv-Lent therapy may be able to enhance the cytotoxic effect of commonly used anticancer drugs such as cisplatin and paclitaxel, and radiotherapy that could provide a promising strategy for the effective control of resistant head and neck cancer.

Development of replication-competent adenovirus for bladder cancer by controlling adenovirus E1a and E4 gene expression with the survivin promoter

Survivin is a member of the inhibitors of apoptosis protein family. Here, we examined survivin expression and confirmed abundant survivin expression in bladder cancer cells. This expression pattern indicated that the transcriptional regulatory elements that control survivin expression could be utilized to discriminate cancer from normal cells. We therefore generated a novel adenovirus termed Ad5/35E1apsurvivinE4 with the following characteristics: 1) E1A and E4 protein expression was dependent on survivin promoter activity; 2) the green fluorescence protein gene was inserted into the genome under the control of the CMV promoter; 3) most of the E3 sequences were deleted, but the construct was still capable of expressing the adenovirus death protein with potent cytotoxic effects; and 4) the fiber knob was from serotype 35 adenovirus. As expected from the abundant survivin expression observed in bladder cancer cells, Ad5/35E1apsurvivinE4 replicated better in cancer cells than in normal cells by a factor of 10⁶ to 10². Likewise, Ad5/35E1apsurvivinE4 exerted greater cytotoxic effects on all bladder cancer cell lines tested. Importantly, Ad5/35E1apsurvivinE4 inhibited the growth of Ku7-Luc orthotopic xenografts in nude mice. Taken together, Ad5/35E1apsurvivinE4 indicates that the survivin promoter may be utilized for the development of a replication-competent adenovirus to target bladder cancers.

Rapid Screening and Structural Characterization of Antioxidants from the Extract of Selaginella doederleinii Hieron with DPPH-UPLC-Q-TOF/MS Method

2,2-Diphenyl-1-picrylhydrazyl-ultra-high performance liquid chromatography-Q-time-of-flight mass spectrometry (DPPH-UPLC-Q-TOF/MS), as a rapid and efficient means, now was used for the first time to screen antioxidants from Selaginella doederleinii. The nine biflavone compounds were screened as potential antioxidants. The biflavones were structurally identified and divided into the three types, that is, amentoflavone-type, robustaflavone-type, and hinokiflavone-type biflavonoids. Among the compounds bilobetin (3) and putraflavone (8) were found from Selaginella doederleinii for the first time and others including amentoflavone (1), robustaflavone (2), 4'-methoxy robustaflavone (4), podocarpusflavone A (5), hinokiflavone (6), ginkgetin (7), and heveaflavone (9) were identified previously in the plant. Moreover, nine biflavones possessed a good antioxidant activity via their DPPH free radical scavenging. It demonstrates that DPPH-UPLC-Q-TOF/MS exhibits strong capacity in separation and identification for small molecule. The method is suitable for rapid screening of antioxidants without the need for complicated systems and additional instruments.

Polypurine reverse Hoogsteen hairpins as a gene therapy tool against survivin in human prostate cancer PC3 cells in vitro and in vivo

As a new approach for gene therapy, we recently developed a new type of molecule called polypurine reverse Hoogsteen hairpins (PPRHs). We decided to explore the in vitro and in vivo effect of PPRHs in cancer choosing survivin as a target since it is involved in apoptosis, mitosis and angiogenesis, and overexpressed in different tumors. We designed four PPRHs against the survivin gene, one of them directed against the template strand and three against different regions of the coding strand. These PPRHs were tested in PC3 prostate cancer cells in an in vitro screening of cell viability and apoptosis. PPRHs against the promoter sequence were the most effective and caused a decrease in survivin mRNA and protein levels. We confirmed the binding between the selected PPRHs and their target sequences in the survivin gene. In addition we determined that both the template- and the coding-PPRH targeting the survivin promoter were interfering with the binding of transcription factors Sp1 and GATA-3, respectively. Finally, we conducted two in vivo efficacy assays using the Coding-PPRH against the survivin promoter and performing two routes of administration, namely intratumoral and intravenous, in a subcutaneous xenograft tumor model of PC3 prostate cancer cells. The results showed that the chosen Coding-PPRH proved to be effective in decreasing tumor volume, and reduced the levels of survivin protein and the formation of blood vessels. These findings represent the preclinical proof of principle of PPRHs as a new silencing tool for cancer gene therapy.

Enhanced inhibition of bladder cancer cell growth by simultaneous knockdown of antiapoptotic Bcl-xL and survivin in combination with chemotherapy

The overexpression of antiapoptotic genes, such as Bcl-xL and survivin, contributes to the increased survival of tumor cells and to the development of treatment resistances. In the bladder cancer cell lines EJ28 and J82, the siRNA-mediated knockdown of survivin reduces cell proliferation and the inhibition of Bcl-xL sensitizes these cells towards subsequent chemotherapy with mitomycin C and cisplatin. Therefore, the aim of this study was to analyze if the simultaneous knockdown of Bcl-xL and survivin might represent a more powerful treatment option for bladder cancer than the single inhibition of one of these target genes. At 96 h after transfection, reduction in cell viability was stronger after simultaneous inhibition of Bcl-xL and survivin (decrease of 40%-48%) in comparison to the single target treatments (decrease of 29% at best). Furthermore, simultaneous knockdown of Bcl-xL and survivin considerably increased the efficacy of subsequent chemotherapy. For example, cellular viability of EJ28 cells decreased to 6% in consequence of Bcl-xL and survivin inhibition plus cisplatin treatment whereas single target siRNA plus chemotherapy treatments mediated reductions down to 15%-36% only. In conclusion, the combination of simultaneous siRNA-mediated knockdown of antiapoptotic Bcl-xL and survivin-a multitarget molecular-based therapy-and conventional chemotherapy shows great potential for improving bladder cancer treatment.

Characterization of three newly established rat sarcoma cell clones

Establishment of new animal models using selected cell lines with different behaviour is very important for cancer investigations. In this study, we describe three morphologically distinct rat sarcoma clones-C4, C7 and D6-isolated from the R5-28 cell line. Cells of all clones expressed vimentin, fibronectin, laminin, collagen IV and matrix metalloproteinases 2 and 9. However, desmin, cytokeratins 8 and 18, ZO-1 and desmoplakins I and II were not detected. Significant proliferative capacity was documented by proliferating cell nuclear antigen expression and BrdU positivity. Karyotype of the C4, C7 and D6 cells greatly differed from diploid chromosome number of normal rat somatic cells. High expression of three cytokines-monocyte chemoattractant protein 1, tissue inhibitor of metalloproteinases 1 and vascular endothelial growth factor-was observed in all three clones. However, they varied in concentration of chemokines associated with neutrophil migration and activation-cytokine induced neutrophil chemoattractant 2 and lipopolysaccharide induced CXC chemokine. The C4 clone showed spontaneous tumour regression in vivo that was associated with significant changes in lymphocyte subpopulations.

Survivin, a target to modulate the radiosensitivity of Ewing's sarcoma

BACKGROUND AND PURPOSE

Radiotherapy constitutes an essential element in the multimodal therapy of Ewing's sarcoma. Compared to other sarcomas, Ewing tumors normally show a good response to radiotherapy. However, there are consistently tumors with a radioresistant phenotype, and the underlying mechanisms are not known in detail. Here we investigated the association between survivin protein expression and the radiosensitivity of Ewing's sarcoma in vitro.

MATERIAL AND METHODS

An siRNA-based knockdown approach was used to investigate the influence of survivin expression on cell proliferation, double-strand break (DSB) induction and repair, apoptosis and colony-forming ability in four Ewing's sarcoma cell lines with and without irradiation.

RESULTS

Survivin protein and mRNA were upregulated in all cell lines tested in a dose-dependent manner. As a result of survivin knockdown, STA-ET-1 cells showed reduced cell proliferation, an increased number of radiation-induced DSBs, and reduced repair. Apoptosis was increased by knockdown alone and increased further in combination with irradiation. Colony formation was significantly reduced by survivin knockdown in combination with irradiation.

CONCLUSION

Survivin is a radiation-inducible protein in Ewing's sarcoma and its down-regulation sensitizes cells toward irradiation. Survivin knockdown in combination with radiation inhibits cell proliferation, repair, and colony formation significantly and increases apoptosis more than each single treatment alone. This might open new perspectives in the radiation treatment of Ewing's sarcoma.

Co-silencing of Birc5 (survivin) and Hspa5 (Grp78) induces apoptosis in hepatoma cells more efficiently than single gene interference

Birc5 (previously known as survivin) is a cancer-specific protein. Due to the upregulation of its expression in various human malignancies and its key role in apoptosis, proliferation and angiogenesis, Birc5 has attracted attention as a target for anticancer therapies. In this study, when Birc5 was silenced in HepG2 cells, 29.7±3.3% cells underwent apoptosis as expected. It was found that the expression levels of glucose-regulated protein 78 (Hspa5, previously known as Grp78) was increased by almost 3-fold in Birc5-silenced HepG2 cells. Hspa5, a master regulator of the anti-apoptotic unfolded protein response signalling network, can also promote tumor proliferation, survival and metastasis. Hence, we hypothesized that the co-silencing of Birc5 and Hspa5 may exert a stronger apoptosis-inducing effect than single gene interference. To verify this, the expression levels of Birc5 and Hspa5 in human hepatocellular carcinoma tissues were determined. Immunohistochemical staining showed that the expression of Birc5 and Hspa5 was elevated in 28 out of 31 samples. Additionally, plasmid-based siRNA against Birc5 and/or Hspa5 were constructed and transfected into the human hepatocellular liver carcinoma cell line, HepG2. Compared with the HepG2 cells, in which Birc5 or Hspa5 were silenced alone, only 44.2±3.4% of the co-silenced cells proliferated, and 40.3±3.7% co-silenced cells underwent apoptosis (p<0.05). Furthermore, tumor formation from inoculated subcutaneous co-silenced cells in nude mice was inhibited significantly. The current study suggests that Birc5 and Hspa5 could be important survival factors for hepatoma carcinoma cells and that the simultaneous knockdown of Birc5 and Hspa5 is more effective in inducing apoptosis in HepG2 cells than the knockdown of Birc5 or Hspa5 alone. The co-silencing of Birc5 and Hspa5 could be warranted for cancer therapy.

Optimization and apoptosis induction by RNAi with UTMD technology in vitro

Apoptosis induction by short hairpin RNA (shRNA) expression vectors may be an efficient and promising strategy for cancer gene therapy. Ultrasound-targeted microbubble destruction (UTMD) is an appealing technique; however, there few data are available to demonstrate the feasibility and to optimize the methodology for this technology. The aim of this study was to optimize this technique and to elucidate the effects on gene inhibition and apoptosis induction in vitro. Human cervical cancer cell lines were obtained and cultured.shRNA vectors were constructed, and the UTMD technique was examined to determine whether or not it was suitable for shRNA transfection into cells. Cells were then examined using flow cytometry. The results revealed that the optimal irradiation parameters obtained higher transfection efficiency and did not affect the integrity of plasmid DNA. We concluded that survivin downregulation with shRNA expression vectors, mediated by the optimal UTMD parameters, markedly induced cell apoptosis and caused cell cycle arrest, laying a foundation for further investigation of this cancer therapy.

Survivin regulation by HER2 through NF-κB and c-myc in irradiated breast cancer cells

Radiotherapy is an important treatment modality against cancer resulting in apoptosis and inhibition of cell growth. Survivin is an important cancer biomarker conferring to tumour cells increased survival potential by inhibiting apoptosis. In the present study, we investigated the implication of breast cancer cells features, as hormone receptors and p53 status, in the radio-resistance of breast cancer cells and in the regulation of survivin's expression by nuclear factor (NF)-κB and c-myc. Six breast cancer cell lines Michigan Cancer Foundation (MCF-7), MCF-7/Human Epidermal Growth Factor Receptor (HER)2, M. D. Anderson - Metastatic Breast (MDA-MB-231), SK-BR-3, BT-474 and Human Breast Lactating (HBL-100) were irradiated and cell viability as well as cell cycle distribution were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. Survivin mRNA and protein levels were evaluated by real time PCR and Western blot analysis. Survivin and HER2 gene knockdown was performed with siRNA technology and investigation of transcription factors binding to survivin and c-myc gene promoters was assessed by chromatin immunoprecipitation. Student's t-test and F-statistics were used for statistical evaluation. Our results demonstrated that only HER2(+) breast cancer cells up-regulated survivin upon irradiation, whereas HER2 knockdown in HER2(+) cells led to survivin's down-regulation. Survivin and especially HER2 knockdown abolished the observed G2/M cell cycle checkpoint and reduced the radio-resistance of HER2 overexpressing breast cancer cells. Additionally, HER2 was found to regulate survivin's expression through NF-κB and c-myc transcription factors. This study revealed the significance of HER2 in the radio-resistance of HER2(+) breast cancer cells through induction of transcription factors NF-κB and c-myc, leading to activation of survivin, a downstream target oncogene preventing apoptosis.

Glioma Growth Inhibition In Vitro and In Vivo by Single Chain Variable Fragments of the Transferrin Receptor Conjugated to Survivin Small Interfering RNA

Inhibition of survivin by small interfering RNA (siRNA) can delay glioma growth. To enhance the effect of survivin-siRNA on intercranial glioma, a conjugate of siRNA-survivin and single-chain variable fragment (scFv) of the transferrin receptor (TfR) was constructed and its effects assessed in vitro and in vivo. Survivin-siRNA and the survivin-siRNA/scFv-TfR conjugate were constructed and used successfully to inhibit glioma U87 cell proliferation and enhance apoptosis in vitro. The molecular constructs were administered to an established U87 orthotopic mouse model. Western blot analysis and immunohistochemistry of the glioma tissues showed that survivin protein levels were strongly suppressed by the survivin-siRNA/scFv-TfR conjugate in vivo. Furthermore, survivin-siRNA/scFv-TfR prolonged the survival time of mice more than survivin-siRNA. In conclusion, the survivin-siRNA/scFv-TfR conjugate efficiently enhanced the effects of survivin-siRNA on glioma suppression in vivo, confirming the applicability of antibody-targeted molecular therapies for treating human brain tumours.

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.

Inhibition of JAK2 signaling by TG101209 enhances radiotherapy in lung cancer models

INTRODUCTION

Persistent STAT3 activation contributes to lung carcinogenesis. Survivin, one of STAT3-regulated genes, is antiapoptotic and confers cancer radioresistance.

METHODS

We tested whether TG101209, a small-molecule inhibitor of JAK2 (a STAT3-activating tyrosine kinase), affected survivin expression and sensitized lung cancer to radiation. We investigated whether inhibition of JAK2 signaling with TG101209 can be used to reduce survivin expression and enhance radiosensitivity of lung cancer cells in vitro and tumor growth delay in vivo. JAK2 downstream signaling, including PI3-K/Akt and Ras/MAPK/ERK pathways, was also explored.

RESULTS

TG101209 inhibited STAT3 activation and survivin expression and sensitized HCC2429 (dose enhancement ratio = 1.34, p = 0.002) and H460 (dose enhancement ratio = 1.09, p = 0.006) cells to radiation in clonogenic assays. Radiation promoted phospho-Akt and phospho-ERK in H460 cells, while their levels were unchanged in HCC2429. After treatment with TG101209, phospho-ERK protein levels were reduced in both HCC2429 and H460 cells. HCC2429 cells transfected with KRAS-12V mutant were more resistant to radiation- and TG101209-induced apoptosis than wild-type control cells. In vivo, addition of TG101209 to radiation in lung xenografts produced a significant tumor growth delay (>10 days) compared with radiation alone and was well tolerated. Immunohistochemistry staining of tumor sections showed that TG101209 increased apoptosis and decreased cell proliferation and vascular density, suggesting that TG101209 also has antiangiogenic effects.

CONCLUSIONS

TG101209 enhanced the effects of radiation in lung cancer in vitro and in vivo. This study suggests the potential utility of selecting lung cancer patients according to KRAS mutation status for future clinical trials testing combination of TG101209 and radiotherapy.

Disabling the mitotic spindle and tumor growth by targeting a cavity-induced allosteric site of survivin

Survivin is a member of the inhibitor of apoptosis protein family and has an essential role in mitosis. Survivin is overexpressed in a large variety of human cancers and represents an attractive target for cancer therapy. Epidermal growth factor receptor and Her/neu-transformed human tumors in particular exhibit high levels of survivin. The survivin protein forms dimers through a conserved region that is critical for subcellular localization and biological functions of the protein. We identified small molecules that target a specific cavity adjacent to the survivin dimerization surfaces. S12, a lead compound identified in the screen, can bind to the survivin protein at the intended target site. Moreover, S12 alters spindle formation, causing mitotic arrest and cell death, and inhibits tumor growth in vitro and in vivo. Cell death occurs in premetaphase stage following mitotic arrest and is not a consequence of general toxicity. Thus, the study validates a novel therapeutic target site in the survivin protein and provides a promising strategy to develop a new class of therapeutic small molecules for the treatment of human cancers.

RNA interference targeting survivin exerts antitumoral effects in vitro and in established glioma xenografts in vivo

Malignant glioma represents the most common primary adult brain tumor in Western industrialized countries. Despite aggressive treatment modalities, the median survival duration for patients with glioblastoma multiforme (GBM), the highest grade malignant glioma, has not improved significantly over past decades. One promising approach to deal with GBM is the inactivation of proteins essential for survival or progression of glioma cells by means of RNA interference (RNAi) techniques. A likely candidate for an RNAi therapy of gliomas is the inhibitor of apoptosis protein survivin. Survivin is involved in 2 main cellular processes-cell division and inhibition of apoptosis. We show here that stable RNAi of survivin induced polyploidy, apoptosis, and impaired proliferation of human U343-MG, U373-MG, H4, and U87-MG cells and of primary glioblastoma cells. Proteome profiler arrays using U373-MG cells identified a novel set of differentially expressed genes upon RNAi-mediated survivin knockdown. In particular, the death receptor TRAIL R2/DR5 was strongly upregulated in survivin-depleted glioma cells, inducing an enhanced cytotoxic response of allogeneic human NK cells. Moreover, an experimental in vivo therapy using polyethylenimine (PEI)/siRNA complexes for survivin knockdown efficiently blocked tumor growth of established subcutaneous U373-MG tumors and enhanced survival of NMRI(nu/nu) mice orthopically transplanted with U87-MG cells. We conclude that survivin is functionally relevant in gliomas and that PEI-mediated exogenous delivery of siRNA targeting survivin is a promising strategy for glioblastoma therapy.

Radiosensitization by inhibiting survivin in human hepatoma HepG2 cells to high-LET radiation

In this study, whether survivin plays a direct role in mediating high-LET radiation resistance in human hepatoma cells was investigated. Small interfering RNA (siRNA) targeting survivin mRNA was designed and transfected into human hepatoma HepG2 cells. Real-time PCR and western blotting analyses revealed that survivin expression in HepG2 cells decreased at both transcriptional and post-transcriptional levels after treatment with survivin-specific siRNA. Caspase-3 activity was determined with a microplate reader assay as well. Following exposure to high-LET carbon ions, a reduced clonogenic survival effect, increased apoptotic rates and caspase-3 activity were observed in the cells treated with the siRNA compared to those untreated with the siRNA. The cells with transfection of the survivin-specific siRNA also increased the level of G₂/M arrest. These results suggest that survivin definitely plays a role in mediating the resistance of HepG2 cells to high-LET radiation and depressing survivin expression might be useful to improve the therapeutic efficacy of heavy ions for radioresistant solid tumors.

Prognostic significance of survivin polymorphisms on non-small cell lung cancer survival

INTRODUCTION

Survivin is an apoptotic inhibitor, involves in regulation of apoptosis and cell cycle progression, and its polymorphisms may influence the development and progression of cancer. This study evaluated the impact of the survivin gene polymorphisms on survival of non-small cell lung cancer (NSCLC) patients.

METHODS

In this case-cohort follow-up study, a total of 568 NSCLC patients were investigated and 12 single nucleotide polymorphisms in survivin gene were genotyped by using the Illumina GoldenGate platform.

RESULTS

During the maximum of 72 months of follow-up, 314 (55.11%) deaths were observed. After adjusting for age, gender, smoking status, histology, stage, surgical operation, and chemotherapy or radiotherapy status, Cox hazard proportional model suggested that four single nucleotide polymorphisms had statistically significant impacts on NSCLC survival (rs3764383, AG/GG versus AA, hazard ratio [HR] = 0.78, 95% confidence interval [CI]: 0.62-0.99; rs8073069, GG versus CG/CC, HR = 1.76, 95% CI: 1.16-2.67; rs4789551, GG versus AG/AA, HR = 2.04, 95% CI: 1.08-3.86; rs1042489, GG versus AG/AA, HR = 1.37, 95% CI: 1.03-1.83). Further combined analysis showed that the high risk group (3-4 unfavorable loci) presented a 1.84-fold (95% CI: 1.22-2.77) increased risk compared with low risk group (0-2 unfavorable loci). Among 185 stage III to IV patients who received only chemotherapy, only the potentially functional rs8073069 still had a significantly increased risk on the prognosis of NSCLC (GG versus CG/CC, HR = 2.06, 95% CI: 1.10-3.87).

CONCLUSIONS

Our results suggest that polymorphisms in survivin may be a genetic modifier for NSCLC prognosis in this Chinese population.

Survival benefit with proapoptotic molecular and pathologic responses from dual targeting of mammalian target of rapamycin and epidermal growth factor receptor in a preclinical model of pancreatic neuroendocrine carcinogenesis

PURPOSE

Pancreatic neuroendocrine tumors (PNETs), although rare, often metastasize, such that surgery, the only potentially curative therapy, is not possible. There is no effective systemic therapy for patients with advanced PNETs. Therefore, new strategies are needed. Toward that end, we investigated the potential benefit of dual therapeutic targeting of the epidermal growth factor receptor (EGFR) and mammalian target of rapamycin (mTOR) kinases, using a preclinical mouse model of PNET.

MATERIALS AND METHODS

Rapamycin and erlotinib, inhibitors of mTOR and EGFR, respectively, were used to treat RIP-Tag2 transgenic mice bearing advanced multifocal PNET. Tumor growth and survival were monitored, and tumors were surveyed for potential biomarkers of response to the therapeutics.

RESULTS

Rapamycin monotherapy was notably efficacious, prolonging survival concomitant with tumor stasis (stable disease). However, the tumors developed resistance, as evidenced by eventual relapse to progressive tumor growth. Erlotinib monotherapy slowed tumor growth and elicited a marginal survival benefit. In combination, there was an unprecedented survival benefit in the face of this aggressive multifocal cancer and, in contrast to either monotherapy, the development of adaptive resistance was not apparent. Additionally, the antiapoptotic protein survivin was implicated as a biomarker of sensitivity and beneficial responses to the dual targeted therapy.

CONCLUSION

Preclinical trials in a mouse model of endogenous PNET suggest that combined targeting of the mTOR and EGFR signaling pathways could have potential clinical benefit in treating PNET. These results have encouraged development of an ongoing phase II clinical trial aimed to evaluate the efficacy of this treatment regimen in human neuroendocrine tumors.

RNAi-mediated inhibition of MSP58 decreases tumour growth, migration and invasion in a human glioma cell line

MSP58, a 58-kD nuclear microspherule protein, is an evolutionarily conserved nuclear protein implicated in the regulation of gene transcription as well as in malignant transformation. An analysis of mRNA expression by real-time PCR revealed that MSP58 was significantly up-regulated in 29% of high-grade glioblastoma tissues as well as in four glioblastoma cell lines. In the present study, we further evaluated the biological functions of MSP58 in U251 glioma cell proliferation, migration, invasion and tumour growth in vivo by specific MSP58 knockdown using short hairpin RNA (shRNA). We found that MSP58 depletion inhibited glioma cell growth, primarily by inducing cell cycle arrest rather than apoptosis. MSP58 depletion also decreased the invasive capability of glioma cells and anchorage-independent colony formation in soft agar. Moreover, suppression of MSP58 expression significantly impaired the growth of glioma xenografts in nude mice. Finally, a cell cycle-associated gene array revealed potential molecular mechanisms contributing to cell cycle arrest in MSP58-depleted glioma cells. In summary, our data highlight the importance of MSP58 in glioma progression and provided a biological basis for MSP58 as a novel candidate target for treatment of glioma.

Efficient siRNA delivery based on PEGylated and partially quaternized polyamine nanogels: enhanced gene silencing activity by the cooperative effect of tertiary and quaternary amino groups in the core

For the development of an siRNA delivery system using polyion complexes (PICs) based on PEGylated nanogel consisting of a cross-linked poly[2-(N,N-diethylaminoethyl) methacrylate] (PEAMA) gel core and tethered poly(ethylene glycol) (PEG) chains, quaternary ammonium groups were introduced in the polyamine gel core to enhance the binding ability with siRNA and the stability of the PICs. Consequently, the quaternization of the polyamine core of the nanogel facilitated the binding ability with siRNA at a low N/P ratio, and the stability against polyanion displacement was enhanced as the degree of quaternization (DQ) of the nanogel increased. Although the installation of the positively charged quaternary ammonium moieties in the core of the nanogel resulted in the increment of the xi-potential of the PICs (e.g. + 23 mV for DQ=100%), the cytotoxicity was reduced with the increase of DQ presumably due to the hydrophilic character of the quaternary ammonium groups. The installation of quaternary ammonium groups in the core of the nanogel enhanced the endogenous gene silencing activity against the survivin gene in human hepatocarcinoma (HuH-7 cells), especially, the partly quaternized polyamine nanogel (DQ=10%) showed the highest gene silencing ability among the quaternized polyamine nanogels, including the tertiary amine nanogel. The cellular uptake analysis of the Rhodamine B-labeled Q-nanogel/fluorescein-labeled siRNA complex revealed that the quaternization of PEAMA moieties enhanced the cellular uptake level of fluorescein-labeled siRNA with the increase in DQ, whereas the cellular uptake of the Rhodamine B-labeled Q-nanogels was almost of the same level regardless of the DQ value, indicating that significant cellular uptake of the fluorescein-labeled siRNA is most likely due to the enhancement of the binding ability with siRNA in the serum-containing medium. Note that the endosomal escape efficiency was reduced with increase in the DQ value due to the decrease in the buffering capacity (tertiary amino groups) of the PEAMA core. On the basis of these results, the ratio of quaternary ammonium groups to tertiary amino groups in the core of the nanogel plays a pivotal role in the achievement of significant gene silencing through enhanced cellular uptake (quaternary ammonium groups) and subsequent endosomal escape (tertiary amino groups).

Novel ultrasound-targeted microbubble destruction mediated short hairpin RNA plasmid transfection targeting survivin inhibits gene expression and induces apoptosis of HeLa cells

Survivin is an attractive target for tumor growth inhibition and represents a significant approach to anticancer therapy. RNA interference is an important tool for specifically down-regulating the expression of cellular genes. However, the efficiency of short hairpin RNA (shRNA) on the expression of survivin gene and the influence on the cell apoptosis transfected by the non-viral gene transfer system of ultrasound-targeted microbubble destruction was not explored. In this work, recombinant expression plasmid of shRNA targeting survivin gene was constructed and added to cultured cervical cancer cells followed by ultrasound exposure and SonoVue((R)) microbubble. Expression of survivin mRNA and protein were assessed by RT-PCR and western blot analysis. Apoptosis ratio was quantified by flow cytometry marked with annexin V and 7-AAD. After transfected for 48 h, the expression of survivin mRNA and protein were (16.67 +/- 2.73)% and (21.33 +/- 3.55)%, respectively. The apoptosis rate was (45.41 +/- 1.47)%. The differences were significant as compared with other groups (P < 0.01). In conclusion, we suggested that survivin could be regarded as an ideal anticancer target of cervical cancer. Recombinant expression plasmid of shRNA targeting survivin gene mediated by ultrasound-targeted microbubble destruction technique could effectively inhibit the expression of target gene and induce cell apoptosis. This novel method for RNA interference represents a powerful, promising non-viral technology that can be used in the tumor gene therapy and research.

Identification and characterization of survivin-derived H-2Kb-restricted CTL epitopes

Survivin is overexpressed in several malignancies and in tumor-associated endothelium making it an attractive target for therapeutic cytotoxic T-cell responses. Thus, it would be important to test this notion in preclinical models. Consequently, we screened the murine survivin sequence for potential binding K(b)-restricted octamer peptide epitopes. Two epitopes, which bind strongly to K(b), were selected to test their immunogenicity in vivo. Spleen cells from mice vaccinated by intradermal injection of mature DC pulsed with these peptides displayed reactivity to the respective epitopes. The natural processing and presentation of these epitopes by tumor cells was evident by the killing of murine melanoma cells by vaccination-induced T cells. Subcutaneous challenge with syngeneic melanoma demonstrated the protective immunity of this vaccination. Notably, analysis of the vessel density in subcutaneous tumors revealed that survivin-specific vaccination significantly reduced the number of intratumoral vessels. In summary, we demonstrated the immunogenicity of two K(b)-restricted peptide epitopes derived from the murine survivin protein; moreover, survivin-specific vaccination not only resulted in a reduction of tumor cells but also the tumor supplying blood vessels. The presented preclinical model for survivin-directed vaccination may serve as a valuable tool to improve already running clinical trials in a syngeneic tumor model.

Therapeutic potential of RNA interference in drug-resistant cancers

Resistance including multidrug resistance to chemotherapy is a common clinical problem in patients suffering from cancer. Multidrug resistance is often mediated by overexpression of transmembrane xenobiotic transport molecules belonging to the superfamily of ATP-binding cassette (ABC)-transporters. Inhibition of ABC-transporters by low-molecular weight compounds in cancer patients has been extensively investigated in clinical trials, but the results have been disappointing. Thus, alternative experimental therapeutic strategies for overcoming multidrug resistance are under investigation. These include the application of RNA interference (RNAi) technology. Various RNAi strategies were applied to reverse multidrug resistance in different tumor models in vitro and in vivo. Results and conclusions of these RNAi studies as well as their potential impact for the development of potential RNAi therapeutics will be discussed.

In vivo reversal of P-glycoprotein-mediated multidrug resistance by efficient delivery of stealth RNAi

P-Glycoprotein-mediated multidrug resistance (MDR) is a major hurdle in cancer therapy. P-Glycoprotein is a 170 KD protein encoded by the MDR1 gene. Over-expression of P-glycoprotein is considered one of the characteristics of the MDR phenotype, thus down-regulation of the MDR1 gene expression will circumvent MDR partly. RNA interference (RNAi) is a process that can result in sequence-specific gene silencing by cleavage target mRNA. Electroporation has been demonstrated to be a promising and efficient method for gene delivery and has been successfully applied in gene therapy. In our study, by using electric pulse to delivery Stealth RNAi into nude mice NCI-H460 tumour xenografts, we successfully inhibited MDR1 both at the mRNA level as determined by reverse transcription-polymerase chain reaction and at the protein level as determined by immunohistochemistry. Furthermore, by administration of navelbine after transfection with Stealth RNAi targeted on the MDR1 gene, its depression to tumour xenografts dramatically improved by nine times. These studies demonstrate that through electrotransfection of Stealth RNAi, P-glycoprotein-mediated MDR can be reversed.

SPC3042: a proapoptotic survivin inhibitor

The ability to regulate the cellular homeostasis of a higher organism through tight control of apoptosis and cell division is crucial for life. Dysregulation of these mechanisms is often associated with cancerous phenotypes in cells. Optimal cancer therapy is a fine balance between effective cancer cell killing and at the same time minimizing, or avoiding, damage to the surrounding healthy tissue. To obtain this, it is necessary to identify and inhibit molecular targets on which the cancer cells are strongly dependent. Survivin represents such a target, and it has been published previously that peptide vaccines, the small-molecule YM155, and the antisense molecule LY2181308/ISIS23722, via different mechanisms, have been used as survivin inhibitors. In this article, a new potent antisense inhibitor of survivin, SPC3042, is presented, and the properties of SPC3042 are compared with the previously published antisense drug, LY2181308/ISIS23722. SPC3042 is a 16-mer locked nucleic acid (LNA) oligonucleotide and designed as a fully phosphorothiolated gapmer containing 7 LNA nucleotides in the flanks. The LNA nucleotides in SPC3042 provide nuclease stability and higher potency for survivin mRNA inhibition compared with earlier generations of antisense reagents. It is shown that the down-regulation of survivin with SPC3042 leads to cell cycle arrest, pronounced cellular apoptosis, and down-regulation of Bcl-2. It is also shown that SPC3042 is a sensitizer of prostate cancer cells to Taxol treatment in vitro and in vivo.

Survivin: key regulator of mitosis and apoptosis and novel target for cancer therapeutics

Survivin, a member of the family of inhibitor of apoptosis proteins, functions as a key regulator of mitosis and programmed cell death. Initially, survivin was described as an inhibitor of caspase-9. However, over the last years, research studies have shown that the role of survivin in cancer pathogenesis is not limited to apoptosis inhibition but also involves the regulation of the mitotic spindle checkpoint and the promotion of angiogenesis and chemoresistance. Survivin gene expression is transcriptionally repressed by wild-type p53 and can be deregulated in cancer by several mechanisms, including gene amplification, hypomethylation, increased promoter activity, and loss of p53 function. This article reviews the multiple functions of survivin in the regulation of apoptosis, the promotion of tumorigenesis, and the development of survivin inhibitors as a novel anticancer therapeutic strategy.

The influence of survivin shRNA on the cell cycle and the invasion of SW480 cells of colorectal carcinoma

BACKGROUND

The objective was to understand the influence of Survivin plasmid with short hairpin RNA (shRNA) on the cell cycle, invasion, and the silencing effect of Survivin gene in the SW480 cell of colorectal carcinoma.

METHODS

A eukaryotic expression vector, PGCH1/Survivin shRNA, a segment sequence of Survivin as target, was created and transfected into colorectal carcinoma cell line SW480 by the non-lipid method. The influence on the Survivin protein was analyzed by Western blotting, while the cell cycle, cell apoptosis were analyzed by flow cytometry, and invasion of the cell was analyzed by Transwell's chamber method.

RESULTS

After the transfection of PGCH1/Survivin shRNA, the expression of Survivin protein in SW480 cells was dramatically decreased by 60.68%, in which the cells were stopped at G2/M phase, even though no apoptosis was detected. The number of transmembranous cells of the experimental group, negative control group, and blank control group were 14.46 +/- 2.11, 25.12 +/- 8.37, and 25.86 +/- 7.45, respectively (P <0.05).

CONCLUSION

Survivin shRNA could significantly reduce the expression of Survivin protein and invasion of SW480 cells. Changes in cell cycle were observed, but no apoptosis was induced.