Survivin: a new target for anti-cancer therapy

Cell death signaling and anticancer therapy

For a long time, it was commonly believed that efficient anticancer regimens would either trigger the apoptotic demise of tumor cells or induce a permanent arrest in the G₁ phase of the cell cycle, i.e., senescence. The recent discovery that necrosis can occur in a regulated fashion and the increasingly more precise characterization of the underlying molecular mechanisms have raised great interest, as non-apoptotic pathways might be instrumental to circumvent the resistance of cancer cells to conventional, pro-apoptotic therapeutic regimens. Moreover, it has been shown that some anticancer regimens engage lethal signaling cascades that can ignite multiple oncosuppressive mechanisms, including apoptosis, necrosis, and senescence. Among these signaling pathways is mitotic catastrophe, whose role as a bona fide cell death mechanism has recently been reconsidered. Thus, anticancer regimens get ever more sophisticated, and often distinct strategies are combined to maximize efficacy and minimize side effects. In this review, we will discuss the importance of apoptosis, necrosis, and mitotic catastrophe in the response of tumor cells to the most common clinically employed and experimental anticancer agents.

Mitotic catastrophe: a mechanism for avoiding genomic instability

The improper distribution of chromosomes during mitosis compromises cellular functions and can reduce cellular fitness or contribute to malignant transformation. As a countermeasure, higher eukaryotes have developed strategies for eliminating mitosis-incompetent cells, one of which is mitotic catastrophe. Mitotic catastrophe is driven by a complex and poorly understood signalling cascade but, from a functional perspective, it can be defined as an oncosuppressive mechanism that precedes (and is distinct from) apoptosis, necrosis or senescence. Accordingly, the disruption of mitotic catastrophe precipitates tumorigenesis and cancer progression, and its induction constitutes a therapeutic endpoint.

Enhancement of cancer vaccine therapy by systemic delivery of a tumor-targeting Salmonella-based STAT3 shRNA suppresses the growth of established melanoma tumors

Cancer vaccine therapies have only achieved limited success when focusing on effector immunity with the goal of eliciting robust tumor-specific T-cell responses. More recently, there is an emerging understanding that effective immunity can only be achieved by coordinate disruption of tumor-derived immunosuppression. Toward that goal, we have developed a potent Salmonella-based vaccine expressing codon-optimized survivin (CO-SVN), referred to as 3342Max. When used alone as a therapeutic vaccine, 3342Max can attenuate growth of aggressive murine melanomas overexpressing SVN. However, under more immunosuppressive conditions, such as those associated with larger tumor volumes, we found that the vaccine was ineffective. Vaccine efficacy could be rescued if tumor-bearing mice were treated initially with Salmonella encoding a short hairpin RNA (shRNA) targeting the tolerogenic molecule STAT3 (YS1646-shSTAT3). In vaccinated mice, silencing STAT3 increased the proliferation and granzyme B levels of intratumoral CD4(+) and CD8(+) T cells. The combined strategy also increased apoptosis in tumors of treated mice, enhancing tumor-specific killing of tumor targets. Interestingly, mice treated with YS1646-shSTAT3 or 3342Max alone were similarly unsuccessful in rejecting established tumors, whereas the combined regimen was highly potent. Our findings establish that a combined strategy of silencing immunosuppressive molecules followed by vaccination can act synergistically to attenuate tumor growth, and they offer a novel translational direction to improve tumor immunotherapy.

Terameprocol (tetra-O-methyl nordihydroguaiaretic acid), an inhibitor of Sp1-mediated survivin transcription, induces radiosensitization in non-small cell lung carcinoma

INTRODUCTION

Survivin, an inhibitor of apoptosis protein and key regulator of mitosis, is up-regulated in a variety of cancers and is often associated with a worse prognosis. Terameprocol down-regulates the Sp1-mediated transcription of survivin and Cdk1, which is important for cell cycle progression and many other proteins. Survivin inhibition has previously been shown to result in the induction of apoptosis and radiosensitization.

METHODS

This study examined the effects of terameprocol administration on survivin transcription and expression in HCC2429 and H460 lung cancer cells. We also examined the combined effects of radiation and terameprocol on apoptosis and radiosensitivity.

RESULTS

Using immunoblot analysis and luciferase assays, we confirmed that terameprocol decreases survivin transcription and protein expression. Ultimately, however, decreases in survivin expression failed to correlate with an increase in apoptosis. Nonetheless, clonogenic assay revealed that terameprocol induces increased radiosensitization in HCC2429 (dose enhancement ratio = 1.26, p = 0.019) and H460 (dose enhancement ratio = 1.18, p = 0.001) cells. Additionally, the data show no effect of terameprocol on cell cycle in either HCC2429 or H460 cells.

CONCLUSIONS

Terameprocol significantly enhances the sensitivity of non-small cell lung carcinoma cell lines to radiation therapy, although the mechanism of action remains unclear. Further study is warranted to assess the potential of terameprocol as an agent that may enhance the therapeutic ratio of radiotherapy in lung cancer.

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.

The antiapoptotic gene survivin is highly expressed in human chondrosarcoma and promotes drug resistance in chondrosarcoma cells in vitro

Background

Chondrosarcoma is virtually resistant to chemotherapy and radiation therapy. Survivin, the smallest member of the inhibitor of apoptosis protein family, is a critical factor for tumor progression and resistance to conventional therapeutic approaches in a wide range of malignancies. However, the role of survivin in chondrosarcoma has not been well studied. We examined the importance of survivin gene expression in chondrosarcoma and analysed its influences on proliferation, apoptosis and resistance to chemotherapy in vitro.

Methods

Resected chondrosarcoma specimens from which paraffin-embedded tissues could be extracted were available from 12 patients. In vitro experiments were performed in human chondrosarcoma cell lines SW1353 and Hs819.T. Immunohistochemistry, immunoblot, quantitative PCR, RNA interference, gene-overexpression and analyses of cell proliferation and apoptosis were performed.

Results

Expression of survivin protein was detected in all chondrosarcoma specimens analyzed, while undetectable in adult human cartilage. RNA interference targeting survivin resulted in a G₂/M-arrest of the cell cycle and led to increased rates of apoptosis in chondrosarcoma cells in vitro. Overexpression of survivin resulted in pronounced resistance to doxorubicin treatment.

Conclusions

These findings indicate that survivin plays a role in the pathogenesis and pronounced chemoresistance of high grade chondrosarcoma. Survivin antagonizing therapeutic strategies may lead to new treatment options in unresectable and metastasized chondrosarcoma.

Human mitochondrial transcription factor A functions in both nuclei and mitochondria and regulates cancer cell growth

Mitochondrial transcription factor A (mtTFA) is one of the high mobility group protein family and is required for both transcription from and maintenance of mitochondrial genomes. However, the roles of mtTFA have not been extensively studied in cancer cells. Here, we firstly reported the nuclear localization of mtTFA. The proportion of nuclear-localized mtTFA varied among different cancer cells. Some mtTFA binds tightly to the nuclear chromatin. DNA microarray and chromatin immunoprecipitation assays showed that mtTFA can regulate the expression of nuclear genes. Overexpression of mtTFA enhanced the growth of cancer cell lines, whereas downregulation of mtTFA inhibited their growth by regulating mtTFA target genes, such as baculoviral IAP repeat-containing 5 (BIRC5; also known as survivin). Knockdown of mtTFA expression induced p21-dependent G1 cell cycle arrest. These results imply that mtTFA functions in both nuclei and mitochondria to promote cell growth.

Inhibitor of Apoptosis (IAP) survivin is indispensable for survival of HER2 gene-amplified breast cancer cells with primary resistance to HER1/2-targeted therapies

Primary resistance of HER2 gene-amplified breast carcinomas (BC) to HER-targeted therapies can be explained in terms of overactive HER2-independent downstream pro-survival pathways. We here confirm that constitutive overexpression of Inhibitor of Apoptosis (IAP) survivin is indispensable for survival of HER2-positive BC cells with intrinsic cross-resistance to multiple HER1/2 inhibitors. The IC₅₀ values for the HER1/2 Tyrosine Kinase Inhibitors (TKIs) gefitinib, erlotinib and lapatinib were up to 40-fold higher in trastuzumab-unresponsive JIMT-1 cells than in trastuzumab-naïve SKBR3 cells. ELISA-based and immunoblotting assays demonstrated that trastuzumab-refractory JIMT-1 cells constitutively expressed ~ 4 times more survivin protein than trastuzumab-responsive SKBR3 cells. In response to trastuzumab, JIMT-1 cells accumulated ~10 times more survivin than SKBR3 cells. HER1/2 TKIs failed to down-regulate survivin expression in JIMT-1 cells whereas equimolar doses of HER1/HER2 TKIs drastically depleted survivin protein in SKBR3 cells. ELISA-based detection of histone-associated DNA fragments confirmed that trastuzumab-refractory JIMT-1 cells were intrinsically protected against the apoptotic effects of HER1/2 TKIs. Of note, when we knocked-down survivin expression using siRNA and then added trastuzumab, cell proliferation and colony formation were completely suppressed in JIMT-1 cells. Our current findings may be extremely helpful to design successful combinatorial strategies aimed to circumvent the occurrence of de novo resistance to HER2-directed drugs using survivin antagonists.

Oxidative stress mediated apoptosis induced by nickel ferrite nanoparticles in cultured A549 cells

Due to the interesting magnetic and electrical properties with good chemical and thermal stabilities, nickel ferrite nanoparticles are being utilized in many applications including magnetic resonance imaging, drug delivery and hyperthermia. Recent studies have shown that nickel ferrite nanoparticles produce cytotoxicity in mammalian cells. However, there is very limited information concerning the toxicity of nickel ferrite nanoparticles at the cellular and molecular level. The aim of this study was to investigate the cytotoxicity, oxidative stress and apoptosis induction by well-characterized nickel ferrite nanoparticles (size 26 nm) in human lung epithelial (A549) cells. Nickel ferrite nanoparticles induced dose-dependent cytotoxicity in A549 cells demonstrated by MTT, NRU and LDH assays. Nickel ferrite nanoparticles were also found to induce oxidative stress evidenced by generation of reactive oxygen species (ROS) and depletion of antioxidant glutathione (GSH). Further, co-treatment with the antioxidant L-ascorbic acid mitigated the ROS generation and GSH depletion due to nickel ferrite nanoparticles suggesting the potential mechanism of oxidative stress. Quantitative real-time PCR analysis demonstrated that following the exposure of A549 cells to nickel ferrite nanoparticles, the level of mRNA expressions of cell cycle checkpoint protein p53 and apoptotic proteins (bax, caspase-3 and caspase-9) were significantly up-regulated, whereas the expression of anti-apoptotic proteins (survivin and bcl-2) were down-regulated. Moreover, activities of caspase-3 and caspase-9 enzymes were also significantly higher in nickel ferrite nanoparticles exposed cells. To the best of our knowledge this is the first report showing that nickel ferrite nanoparticles induced apoptosis in A549 cells through ROS generation and oxidative stress via p53, survivin, bax/bcl-2 and caspase pathways.

Targeting survivin in cancer: patent review

IMPORTANCE OF THE FIELD

Survivin is a prominent anti-apoptotic molecule expressed widely in the majority of cancers. Overexpression of survivin leads to uncontrolled cancer cell growth and drug resistance. Efficient downregulation of survivin expression and its functions can sensitise the tumour cells to various therapeutic interventions such as chemotherapeutic agents leading to cell apoptosis.

AREAS COVERED IN THIS REVIEW

The article thoroughly analyses up-to-date information on the knowledge generated from the survivin patents. Various key areas of research in terms of understanding survivin biology and its targeting are discussed in detail.

WHAT THE READER WILL GAIN

The article clearly gives an insight on the recent developments undertaken to understand the roles of survivin in cancer and in validating various treatment paradigms that suppress survivin expression in cancer cells.

TAKE HOME MESSAGE

Most recent developments are helpful for effectively downregulating survivin expression by using various therapeutic platforms such as chemotherapeutic drugs, immunotechnology, antisense, dominant negative survivin mutant, RNA interference and peptide-based methods. However, selective and specific targeting of survivin in cancer cells still poses a major challenge. Nanotechnology-based platforms are currently under development to enable site-specific targeting of survivin in tumour cells.

Apoptotic cell signaling in cancer progression and therapy

Apoptosis is a tightly regulated cell suicide program that plays an essential role in the development and maintenance of tissue homeostasis by eliminating unnecessary or harmful cells. Impairment of this native defense mechanism promotes aberrant cellular proliferation and the accumulation of genetic defects, ultimately resulting in tumorigenesis, and frequently confers drug resistance to cancer cells. The regulation of apoptosis at several levels is essential to maintain the delicate balance between cellular survival and death signaling that is required to prevent disease. Complex networks of signaling pathways act to promote or inhibit apoptosis in response to various cues. Apoptosis can be triggered by signals from within the cell, such as genotoxic stress, or by extrinsic signals, such as the binding of ligands to cell surface death receptors. Various upstream signaling pathways can modulate apoptosis by converging on, and thereby altering the activity of, common central control points within the apoptotic signaling pathways, which involve the BCL-2 family proteins, inhibitor of apoptosis (IAP) proteins, and FLICE-inhibitory protein (c-FLIP). This review highlights the role of these fundamental regulators of apoptosis in the context of both normal apoptotic signaling mechanisms and dysregulated apoptotic pathways that can render cancer cells resistant to cell death. In addition, therapeutic strategies aimed at modulating the activity of BCL-2 family proteins, IAPs, and c-FLIP for the targeted induction of apoptosis are briefly discussed.

Unliganded progesterone receptors attenuate taxane-induced breast cancer cell death by modulating the spindle assembly checkpoint

Whether the presence of steroid receptors in luminal breast cancers renders them resistant to taxanes remains uncertain. Here we assess the role of progesterone receptors (PR) on taxane-induced cell death. We previously showed that estrogen receptor (ER)-positive human breast cancer cells that inducibly express PR-A or PR-B isoforms were protected from taxane-stimulated apoptosis when compared to the identical cells lacking PR. Surprisingly, PR-dependent protection occurred in the absence of progesterone, demonstrating that the unliganded receptors were biologically active. The present studies demonstrate that unliganded PR, focused on PR-A, protect breast cancer cells from taxane-stimulated apoptosis. The studies identify genes regulated by taxanes in isogenic ER-positive cells that either lack or express PR-A. We show that unliganded PR-A alters the gene expression pattern controlled by taxanes, especially multiple genes involved in the spindle assembly checkpoint, a group of proteins that insure proper attachment of microtubules to kinetochores during mitosis. Importantly, taxanes and unliganded PR regulate many of these genes in opposite directions. As a result, mitotic slippage is exacerbated by the presence of PR, leading to an increase in the number of multinucleated cells both in vitro and in xenograft tumors. We describe a simple new assay for assessing multinucleation in paraffin sections. We speculate that rather than inducing cell death, unliganded PR exploits multinucleation to promote cell survival from taxane therapy. This can be prevented with antiprogestin.

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.

Potential clinical applications of siRNA technique: benefits and limitations

BACKGROUND

RNA interference (RNAi) has become the method of choice for researchers wishing to target specific genes for silencing and has provided immense potential as therapeutic tools. This narrative review article aimed to understand potential benefits and limitations of RNAi technique for clinical application and in vivo studies through reading the articles published during the recent 3 years.

MATERIALS AND METHODS

Medline database was searched by using 'siRNA' or 'RNAi' and 'in vivo' with limits of dates 'published in the last 3 years', language 'English' and article type 'clinical trial' for obtaining articles on in vivo studies on the use of RNAi technique. Characteristics of clinical trials on siRNA registered at the http://www.ClinicalTrials.gov were analysed.

RESULTS

The only three clinical studies published so far and many in vivo studies in animals showed that the RNAi technique is safe and effective in treatment of cancers of many organ/systems and various other diseases including viral infection, arterial restenosis and some hereditary diseases with considerable benefits such as high specificity, many possible routes of administration and possibility of silencing multiple genes at the same time. Limitations and uncertainty include efficiency of cellular uptake, specific guidance to the target tissue or cell, long-term safety, sustained efficacy and rapid clearance from the body.

CONCLUSIONS

RNAi technique will become an important and potent weapon for fighting against various diseases. RNAi technique has benefits and limitations in its potential clinical applications. Overcoming the obstacles is still a formidable task.

Zoledronic acid directly suppresses cell proliferation and induces apoptosis in highly tumorigenic prostate and breast cancers

Background:

Bisphosphonates (BPs) were designed for the prevention of skeletal-related events secondary to bone metastases. The purpose of this study was to show that zoledronic acid (ZA) directly eradicates highly tumorigenic and potentially metastatic cancer cells.

Materials and Methods:

Human prostate and breast highly tumorigenic (PC3, MCF 7) and low- or non-tumorigenic (LNCaP, MCF 10a) cell lines, respectively, were exposed to different concentrations of ZA (0-10 μM). Reverse transcriptase double quantitative polymerase chain reaction was used for quantitative gene expression analysis. Apoptosis and cell proliferation were determined using microscopic observation and MTS assays. Western blot was used to confirm the translational effects of apoptotic genes on protein expression.

Results:

Human prostate and breast highly tumorigenic (PC3, MCF 7) and low- or non-tumorigenic (LNCaP, MCF 10a) cell lines, respectively, showed multiple genes demonstrating differential expressions, including TRAF, TRADD, BCL2, CASPASES and IAP families. Increasing ZA concentrations showed a greater concentration-time response on cell proliferation and apoptosis in the highly tumorigenic cells. These results were confirmed by both reversing and enhancing the effect of ZA on cell proliferation with caspase 3, 7 or survivin siRNA, respectively. Pro-apoptotic proteins bax and caspase 2, 3, 7 and 9 were up-regulated, while the anti-apoptotic proteins bcl2, birc3 and survivin were down-regulated only in the highly tumorigenic cells.

Conclusions:

This explains the ability of ZA to inhibit bony metastasis in highly tumorigenic cells compared with the low- or non-tumorigenic cells through a significant decrease in cell proliferation and increase in apoptosis through gene-regulated and translational-mediated down-regulation of survivin coupled with the inhibition of caspase 3 or 7. This has significant implications toward understanding the pharmacophysiology of BPs in metastasis and supports the clinically observed effect of BPs when administered adjunctively with anticancer drugs such as cyclophosphamide/methotrexate/5-fluorouracil, epirubicin in combination with cyclophosphamide or docetaxel, and doxorubicin.

Potential targets for molecular imaging of apoptosis resistance in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers, which is mainly a concern in Southeast Asia. Apoptosis resistance in HCC is one of the significant factors for hepatocarcinogenesis and tumour progression. Recent advances of apoptosis resistance mechanisms in HCC could serve as potential targets for molecular imaging, which would be of considerable value to explore the molecular processes involved in HCC progression and to evaluate responses of certain anti-HCC therapies. Disruptions in the balance of anti-apoptotic and pro-apoptotic processes have been found to be involved in apoptosis resistance in HCC. Loss of response to death receptors, transformation of growth factor-β induced apoptosis, upregulation of anti-apoptotic Bcl-2 subgroup, as well as downregulation of pro-apoptotic Bax subgroup and BH3-only subgroup, are associated with apoptosis resistance in HCC. Mutation of p53 gene, dysregulation of NF-κB and survivin are also of interest because of their contribution to HCC development. In this review, the aim is to identify potential targets for molecular imaging of apoptosis resistance in HCC.

Role of Notch and its oncogenic signaling crosstalk in breast cancer

The Notch signaling plays a key role in cell differentiation, survival, and proliferation through diverse mechanisms. Notch signaling is also involved in vasculogenesis and angiogenesis. Moreover, Notch expression is regulated by hypoxia and inflammatory cytokines (IL-1, IL-6 and leptin). Entangled crosstalk between Notch and other developmental signaling (Hedgehog and Wnt), and signaling triggered by growth factors, estrogens and oncogenic kinases, could impact on Notch targeted genes. Thus, alterations of the Notch signaling can lead to a variety of disorders, including human malignancies. Notch signaling is activated by ligand binding, followed by ADAM/tumor necrosis factor-α-converting enzyme (TACE) metalloprotease and γ-secretase cleavages that produce the Notch intracellular domain (NICD). Translocation of NICD into the nucleus induces the transcriptional activation of Notch target genes. The relationships between Notch deregulated signaling, cancer stem cells and the carcinogenesis process reinforced by Notch crosstalk with many oncogenic signaling pathways suggest that Notch signaling may be a critical drug target for breast and other cancers. Since current status of knowledge in this field changes quickly, our insight should be continuously revised. In this review, we will focus on recent advancements in identification of aberrant Notch signaling in breast cancer and the possible underlying mechanisms, including potential role of Notch in breast cancer stem cells, tumor angiogenesis, as well as its crosstalk with other oncogenic signaling pathways in breast cancer. We will also discuss the prognostic value of Notch proteins and therapeutic potential of targeting Notch signaling for cancer treatment.

Simple solid-phase synthesis and biological properties of carbohydrate-oligonucleotide conjugates modified at the 3'-terminus

A novel synthesis method for oligonucleotides possessing a functional moiety at the 3'-terminus was established based on solid-phase synthesis. In order to install the functional group at the 3'-terminus of the oligonucleotide, a solid support possessing the functional group was prepared. A carbohydrate was employed in this study for the functionalization of the oligonucleotide. To prepare a glycosylated solid support, a novel glycosyl acceptor (2) was synthesized using 4,4-dihydroxymethyl-cyclopenta-1-ene as the starting compound. The glycosylation reaction proceeded smoothly (yield = 95%) to yield the suitable glycosylated compound (3). After 8 was immobilized on the solid support, it was subjected to solid-phase oligonucleotide synthesis by the standard phosphoramidite coupling method. An oligonucleotide possessing a sugar moiety at the 3'-terminus was obtained after the products were deprotected and cleaved from the solid support. The stability of the carbohydrate-modified oligonucleotide was greatly increased even in the serum buffer, indicating that the sugar moiety at the 3'-position improved the resistance against enzymatic degradation. This technique was also applied to RNA synthesis. Galactose-ended siRNA was prepared and was confirmed to possess enough ability, at a concentration of 10 nM, to regulate the expression of the target gene.

Quantum dot-antisense oligonucleotide conjugates for multifunctional gene transfection, mRNA regulation, and tracking of biological processes

It was demonstrated that oligonucleotides, independent of their base sequence and length, could effectively induce the cellular uptake of mercapto acid-capped CdTe QDs after the oligonucleotides were covalently attached on the surface of the QDs. Following these experimental observations, a conjugate composed of covalently linked anti-survivin antisense oligonucleotides (ASON) and CdTe QDs was designed and synthesized. Then, the survivin mRNA down-regulation and the apoptosis of HeLa cells induced by ASON were studied. Systematic experimental results revealed that CdTe-ASON could effectively induce the apoptosis of HeLa cells, while CdTe QDs offered the possibility to visualize the specific intracellular localization of the CdTe-ASON probes strongly associated with their biological functions.

Novel oligonucleotide carrier as scavenger for reactive oxygen species

A novel oligonucleotide carrier which can scavenge ROS is described. The synthesized graft polymer is composed of a PEG segment and a TEMPO-containing hydrophobic segment for scavenging ROS. This graft polymer can form a PIC through electrostatic interaction with oligonucleotides such as siRNA. The amount of ROS was monitored by fluorescence measurements using H₂ DCFDA as a probe, and it was confirmed that the ROS level was effectively suppressed. The cellular uptake of PIC containing the fluorescence-labeled oligonucleotide was evaluated by fluorescence microscopy. Delivered siRNA suppressed the expression of the mRNA. The prepared graft copolymer is thus a promising candidate as a novel oligonucleotide carrier which also reduces ROS damage generated by cationic polymer carriers.

Antioxidant and antiproliferative properties of water extract from Mahonia bealei (Fort.) Carr. leaves

Mahonia bealei (Fort.) Carr. (Berberidaceae) leaves have been widely used as a tea leaf beverage south of the Qinling Mountains of China. In this study, the antioxidant and antiproliferative properties of M. bealei leaves were investigated. Our data showed that the water extract of M. bealei leaves (WML) exhibited extremely high antioxidant properties, which were demonstrated by its ability to scavenge 50% of 1,1-diphenyll-2-2-pricylhydrazyl (DPPH) free radicals at 60.46 μg/ml, and it eliminated approximately 71.19% of superoxide radicals at 500 μg/ml. In addition, the WML showed strong reducing abilities and provided protection against oxidative protein damage induced by hydroxyl radicals. Cellular proliferation and the induction of apoptosis were also examined by cellular proliferation assay, flow cytometry, and mRNA expression analysis. These results demonstrate that WML significantly inhibited the growth of human colon cancer (HT-29) cells in a concentration-dependent manner, and it gradually increased the proportion of apoptotic cells and reduced the expression of the survivin gene. The bioactivity-guided study of WML resulted in the isolation and identification of berberine, a known isoquinoline alkaloid. Berberine exhibited strong antiproliferative activity on HT-29 cells, with IC(50) values of 36.54 μM, suggesting it is, in part, responsible of the anticancer activity of WML.

Visceral regeneration in a sea cucumber involves extensive expression of survivin and mortalin homologs in the mesothelium

Background

The proper balance of cell division and cell death is of crucial importance for all kinds of developmental processes and for maintaining tissue homeostasis in mature tissues. Dysregulation of this balance often results in severe pathologies, such as cancer. There is a growing interest in understanding the factors that govern the interplay between cell death and proliferation under various conditions. Survivin and mortalin are genes that are known to be implicated in both mitosis and apoptosis and are often expressed in tumors.

Results

The present study takes advantage of the ability of the sea cucumber Holothuria glaberrima Selenka, 1867 (Holothuroidea, Aspidochirota) to discard its viscera and completely regrow them. This visceral regeneration involves an extensive expression of survivin and mortalin transcripts in the gut mesothelium (the outer tissue layer of the digestive tube), which coincides in time with drastic de-differentiation and a burst in cell division and apoptosis. Double labeling experiments (in situ hybridization combined with TUNEL assay or with BrdU immunohistochemistry) suggest that both genes support cell proliferation, while survivin might also be involved in suppression of the programmed cell death.

Conclusions

Visceral regeneration in the sea cucumber H. glaberrima is accompanied by elevated levels of cell division and cell death, and, moreover, involves expression of pro-cancer genes, such as survivin and mortalin, which are known to support proliferation and inhibit apoptosis. Nevertheless, once regeneration is completed and the expression pattern of both genes returns to normal, the regrown digestive tube shows no anomalies. This strongly suggests that sea cucumbers must possess some robust cancer-suppression mechanisms that allow rapid re-growth of the adult tissues without leading to runaway tumor development.

Validation of cytoplasmic-to-nuclear ratio of survivin as an indicator of improved prognosis in breast cancer

Background

Conflicting data exist regarding the prognostic and predictive impact of survivin (BIRC5) in breast cancer. We previously reported survivin cytoplasmic-to-nuclear ratio (CNR) as an independent prognostic indicator in breast cancer. Here, we validate survivin CNR in a separate and extended cohort. Furthermore, we present new data suggesting that a low CNR may predict outcome in tamoxifen-treated patients.

Methods

Survin expression was assessed using immunhistochemistry on a breast cancer tissue microarray (TMA) containing 512 tumours. Whole slide digital images were captured using an Aperio XT scanner. Automated image analysis was used to identify tumour from stroma and then to quantify tumour-specific nuclear and cytoplasmic survivin. A decision tree model selected using a 10-fold cross-validation approach was used to identify prognostic subgroups based on nuclear and cytoplasmic survivin expression.

Results

Following optimisation of the staining procedure, it was possible to evaluate survivin protein expression in 70.1% (n = 359) of the 512 tumours represented on the TMA. Decision tree analysis predicted that nuclear, as opposed to cytoplasmic, survivin was the most important determinant of overall survival (OS) and breast cancer-specific survival (BCSS). The decision tree model confirmed CNR of 5 as the optimum threshold for survival analysis. Univariate analysis demonstrated an association between a high CNR (>5) and a prolonged BCSS (HR 0.49, 95% CI 0.29-0.81, p = 0.006). Multivariate analysis revealed a high CNR (>5) was an independent predictor of BCSS (HR 0.47, 95% CI 0.27-0.82, p = 0.008). An increased CNR was associated with ER positive (p = 0.045), low grade (p = 0.007), Ki-67 (p = 0.001) and Her2 (p = 0.026) negative tumours. Finally, a high CNR was an independent predictor of OS in tamoxifen-treated ER-positive patients (HR 0.44, 95% CI 0.23-0.87, p = 0.018).

Conclusion

Using the same threshold as our previous study, we have validated survivin CNR as a marker of good prognosis in breast cancer in a large independent cohort. These findings provide robust evidence of the importance of survivin CNR as a breast cancer biomarker, and its potential to predict outcome in tamoxifen-treated patients.

Phase I study of LY2181308, an antisense oligonucleotide against survivin, in patients with advanced solid tumors

PURPOSE

LY2181308 is an antisense oligonucleotide that complementarily binds to survivin mRNA and inhibits its expression in tumor tissue. This phase I dose escalation study evaluated the tolerability, pharmacokinetics, and anticancer activity of LY2181308 in Japanese.

METHODS

Patients with solid tumors refractory to standard therapy received LY2181308 (400, 600, or 750 mg) as a 3-h intravenous infusion for 3 consecutive days and thereafter once a week.

RESULTS

LY2181308 was administered to 14 patients, aged 44-73 (median 60) years. Flu-like syndrome, prolonged prothrombin time-international normalized ratio (PT-INR), thrombocytopenia, and fatigue were common reversible grade 1/2 toxicities. The dose-limiting toxicity was reversible grade 3 elevation of ALT/AST/γ-GTP in 1 patient treated at the 750-mg dose. Pharmacokinetic analysis showed a long terminal half-life of 21 days and an extensive tissue distribution of LY2181308. In 12 evaluable patients, one patient had stable disease, while the remaining 11 patients had progressive disease.

CONCLUSIONS

LY2181308 monotherapy is well tolerated up to 750 mg with a manageable toxicity, the pharmacokinetic profile warrants further evaluation of LY2181308 in combination with cytotoxic agents or radiotherapy.

Prognostic significance of nuclear survivin expression in resected adenoid cystic carcinoma of the head and neck

OBJECTIVES

The expression of survivin, an inhibitor of apoptosis, in tumor cells is associated with poor clinical outcome for various cancers. We conducted this study to determine survivin expression in patients with adenoid cystic carcinoma (ACC) of the head and neck and to identify its clinical significance as a prognostic factor.

MATERIALS AND METHODS

We performed immunohistochemical staining for survivin, p53, bcl-2 protein, and Ki-67 in formalin fixed, paraffin-embedded blocks from 37 cases of head and neck ACC. We also reviewed the patients' clinical records to determine the association of staining with clinical course.

RESULTS

Of the 37 cases of head and neck ACC, 31 (83.8%) were positive for cytoplasmic survivin expression, and 23 (62.2%) were positive for nuclear survivin expression. There was a significant association between nuclear survivin expression and bcl-2 (P = 0.031). A larger tumor was more commonly a survivin-positive tumor (cytoplasmic survivin, P = 0.043; nuclear survivin, P = 0.057). Median overall survival (OS) was significantly longer in patients not expressing nuclear survivin (P = 0.035). A multivariate analysis revealed that nuclear survivin expression significantly impacted OS (hazard ratio 8.567, P = 0.018) in addition to lymph node involvement (hazard ratio 7.704, P = 0.016).

CONCLUSIONS

The immunohistochemical expression of nuclear survivin has a prognostic impact in patients with head and neck ACC. These results suggest that nuclear survivin expression may be a useful biomarker for predicting prognosis in patients with head and neck ACC who were treated with surgical resection.

Significance of survivin and Bcl-2 homologous antagonist/killer mRNA in detection of bone metastasis in patients with breast cancer

The aim of this study was to assess the diagnostic value of survivin and Bcl-2 homologous antagonist/killer (Bak) mRNA in the detection of patients with bone metastatic breast cancer. This study included 92 patients with breast carcinoma (54 non-metastatic and 38 bone metastatic) and 31 patients with benign breast lesions. Survivin in cell lysates was measured by ELISA while tissue Bak mRNA was detected by RT-PCR. Survivin was significantly increased in bone metastatic breast cancer patients compared to non-metastatic cases or benign ones. Bak mRNA was markedly decreased in bone metastatic patients compared to non-metastatic ones, while significant expression of Bak mRNA was observed in bone metastatic cases compared to benign patients. High survivin level was associated with high grade, late stages and lymph node involvement, whereas low Bak mRNA was associated with late stages. Our data indicate that survivin and Bak mRNA were considerable markers for the identification of breast cancer patients with bone metastasis.

Induction of growth arrest by miR-542-3p that targets survivin

Survivin is a protein which functions as a mitotic regulator as well as apoptosis inhibitor. In this study, we show that introduction of synthetic miR-542-3p mimetic reduced both mRNA and protein levels of survivin. In A549 cells, luciferase reporter assay revealed that miR-542-3p targeted predicted binding sites in the 3'-untranslated region (3'-UTR) of survivin. We also demonstrate that ectopic expression of miR-542-3p inhibited cell proliferation by inducing Gap 1 (G1) and Gap 2/Mitosis (G2/M) cell cycle arrest. Collectively, these results suggest that survivin is a direct target of miR-542-3p and growth inhibition by miR-542-3p may have a potential utility as an anti-cancer therapy.

The neem limonoids azadirachtin and nimbolide induce cell cycle arrest and mitochondria-mediated apoptosis in human cervical cancer (HeLa) cells

Limonoids from the neem tree (Azadirachta indica) have attracted considerable research attention in recent years owing to their potent antioxidant and anti-proliferative effects. The present study was designed to investigate the cellular and molecular mechanisms by which azadirachtin and nimbolide exert cytotoxic effects in the human cervical cancer (HeLa) cell line. Both azadirachtin and nimbolide significantly suppressed the viability of HeLa cells in a dose-dependent manner by inducing cell cycle arrest at G0/G1 phase accompanied by p53-dependent p21 accumulation and down-regulation of the cell cycle regulatory proteins cyclin B, cyclin D1 and PCNA. Characteristic changes in nuclear morphology, presence of a subdiploid peak and annexin-V staining pointed to apoptosis as the mode of cell death. Increased generation of reactive oxygen species with decline in the mitochondrial transmembrane potential and release of cytochrome c confirmed that the neem limonoids transduced the apoptotic signal via the mitochondrial pathway. Altered expression of the Bcl-2 family of proteins, inhibition of NF-kappaB activation and over-expression of caspases and survivin provide compelling evidence that azadirachtin and nimbolide induce a shift of balance toward a pro-apoptotic phenotype. Antioxidants such as azadirachtin and nimbolide that can simultaneously arrest the cell cycle and target multiple molecules involved in mitochondrial apoptosis offer immense potential as anti-cancer therapeutic drugs.

Antagonists of IAP proteins as cancer therapeutics

Inhibitor of apoptosis (IAP) proteins play pivotal roles in cellular survival by blocking apoptosis, modulating signal transduction, and affecting cellular proliferation. Through their interactions with inducers and effectors of apoptosis IAP proteins can effectively suppress apoptosis triggered by diverse stimuli including death receptor signaling, irradiation, chemotherapeutic agents, or growth factor withdrawal. Evasion of apoptosis, in part due to the action of IAP proteins, enhances resistance of cancer cells to treatment with chemotherapeutic agents and contributes to tumor progression. Additionally, IAP genes are known to be subject to amplification, mutation, and chromosomal translocation in human malignancies and autoimmune diseases. In this review we will discuss the role of IAP proteins in cancer and the development of antagonists targeting IAP proteins for cancer treatment.

Treatment of cancer patients with a serotype 5/3 chimeric oncolytic adenovirus expressing GMCSF

Augmenting antitumor immunity is a promising way to enhance the potency of oncolytic adenoviral therapy. Granulocyte-macrophage colony-stimulating factor (GMCSF) can mediate antitumor effects by recruiting natural killer cells and by induction of tumor-specific CD8(+) cytotoxic T-lymphocytes. Serotype 5 adenoviruses (Ad5) are commonly used in cancer gene therapy. However, expression of the coxsackie-adenovirus receptor is variable in many advanced tumors and preclinical data have demonstrated an advantage for replacing the Ad5 knob with the Ad3 knob. Here, a 5/3 capsid chimeric and p16-Rb pathway selective oncolytic adenovirus coding for GMCSF was engineered and tested preclinically. A total of 21 patients with advanced solid tumors refractory to standard therapies were then treated intratumorally and intravenously with Ad5/3-D24-GMCSF, which was combined with low-dose metronomic cyclophosphamide to reduce regulatory T cells. No severe adverse events occurred. Analysis of pretreatment samples of malignant pleural effusion and ascites confirmed the efficacy of Ad5/3-D24-GMCSF in transduction and cell killing. Evidence of biological activity of the virus was seen in 13/21 patients and 8/12 showed objective clinical benefit as evaluated by radiology with Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Antiadenoviral and antitumoral immune responses were elicited after treatment. Thus, Ad5/3-D24-GMCSF seems safe in treating cancer patients and promising signs of efficacy were seen.

The Polyvalent Gold Nanoparticle Conjugate-Materials Synthesis, Biodiagnostics, and Intracellular Gene Regulation

Advances in nanoscale directed assembly strategies have enabled researchers to analogize atomic assembly via chemical reactions and nanoparticle assembly, creating a new nanoscale "periodic table." We are just beginning to realize the nanoparticle equivalents of molecules and extended materials and are currently developing the ground rules for creating programmable nanometer-scale coordination environments. The ability to create a diverse set of nanoscale architectures from one class of nanoparticle building blocks would allow for the synthesis of designer materials, wherein the physical properties of a material could be predicted and controlled a priori. Our group has taken the first steps toward this goal and developed a means of creating tailorable assembly environments using DNA-nanoparticle conjugates. These nanobioconjugates combine the discrete plasmon resonances of gold nanoparticles with the synthetically controllable and highly selective recognition properties of DNA. Herein, we elucidate the beneficial properties of these materials in diagnostic, therapeutic, and detection capabilities and project their potential use as nanoscale assembly agents to realize complex three-dimensional nanostructures.

Prognostic significance of survivin expression in renal cell cancer and its correlation with radioresistance

Survivin, an important inhibitor of apoptosis, has been found to play an important role in the initiation, progression, and chemoradioresistance of human malignancies. Previously, we have reported that upregulation of survivin in oral squamous cell carcinoma correlates with poor prognosis and chemoresistance. The aim of this study was to assess prognostic significance of survivin protein expression in RCC and analyze its correlation with radiosensitivity of RCC cells. RT-PCR and Western blot assays were performed to detect survivin mRNA and protein expression in normal human kidney epithelial cell line (HKEC) or RCC cell lines. The expression of survivin mRNA in RCC and corresponding nontumor kidney tissues was also detected by RT-PCR. Immunohistochemistry was performed to determine survivin protein expression in 75 cases of RCC tissue samples. Moreover, the association of survivin protein expression with clinicopathogical factors and prognosis of RCC patients was statistically analyzed. Small interfering RNA was used to knockdown the endogenous survivin expression in RCC cell line (ACHN) and evaluate the effects of survivin knockdown on proliferation, apoptosis, and radiosensitivity of RCC cell line. RCC cells showed sufficient expression of survivin mRNA and protein, but the expression of survivin gene was not detected in normal HKEC. Moreover, the expression level of survivin mRNA in RCC tissues was significantly higher than that in corresponding nontumor kidney tissues. The immunostaining of survivin protein was mainly located in cytoplasm of RCC tumor cells. Tumor pathological stage (P = 0.028), grade (P = 0.004), and lymph node metastasis (P = 0.017) of RCC patients were significantly correlated with survivin protein expression. In addition, patients with high survivin levels had a significantly shorter overall survival than those with low levels (P < 0.001), and the expression of survivin protein was an independent prognostic factor for RCC patients (P = 0.008). The expression of survivin gene could be reduced in RCC cell line and survivin knockdown could inhibit growth and enhance in vivo radiosensitivity of RCC cell line by inducing apoptosis enhancement. Taken together, the status of survivin protein expression may be an independent factor for predicting the prognosis of RCC patients and tumor-specific survivin knockdown combined with radiotherapy will be a potential strategy for RCC therapy.

Down-regulation of telomerase activity and activation of caspase-3 are responsible for Tanshinone I-induced apoptosis in monocyte leukemia cells in vitro

Tanshinone I (Tan-I) is a diterpene quinone extracted from the traditional herbal medicine Salvia miltiorrhiza Bunge. Recently, Tan-I has been reported to have anti-tumor effects. In this study, we investigated the growth inhibition and apoptosis inducing effects of Tan-I on three kinds of monocytic leukemia cells (U937, THP-1 and SHI 1). Cell viability was measured by MTT assay. Cell apoptosis was assessed by flow cytometry (FCM) and AnnexinV/PI staining. Reverse transcriptase polymerase chain reaction (RT-PCR) and PCR-enzyme-linked immunosorbent assay (ELISA) were used to detect human telomerase reverse transcriptase (hTERT) expression and telomerase activity before and after apoptosis. The activity of caspase-3 was determined by Caspase colorimetric assay kit and Western blot analysis. Expression of the anti-apoptotic gene Survivin was assayed by Western blot and Real-time RT-PCR using the ABI PRISM 7500 Sequence Detection System. The results revealed that Tan-I could inhibit the growth of these three kinds of leukemia cells and cause apoptosis in a time- and dose-dependent manner. After treatment by Tan-I for 48 h, Western blotting showed cleavage of the caspase-3 zymogen protein with the appearance of its 17-kD subunit, and a 89-kD cleavage product of poly (ADP-ribose) polymerase (PARP), a known substrate of caspase-3, was also found clearly. The expression of hTERT mRNA as well as activity of telomerase were decreased concurrently in a dose-dependent manner. Moreover, Real-time RT-PCR and Western blot revealed a significant down-regulation of Survivin. We therefore conclude that the induction of apoptosis by Tan-I in monocytic leukemia U937 THP-1 and SHI 1 cells is highly correlated with activation of caspase-3 and decreasing of hTERT mRNA expression and telomerase activity as well as down-regulation of Survivin expression. To our knowledge, this is the first report about the effects of Tan-I on monocytic leukemia cells.

Oncolytic adenovirus coding for granulocyte macrophage colony-stimulating factor induces antitumoral immunity in cancer patients

Granulocyte macrophage colony-stimulating factor (GMCSF) can mediate antitumor effects by recruiting natural killer cells and by induction of tumor-specific cytotoxic T-cells through antigen-presenting cells. Oncolytic tumor cell-killing can produce a potent costimulatory danger signal and release of tumor epitopes for antigen-presenting cell sampling. Therefore, an oncolytic adenovirus coding for GMCSF was engineered and shown to induce tumor-specific immunity in an immunocompetent syngeneic hamster model. Subsequently, 20 patients with advanced solid tumors refractory to standard therapies were treated with Ad5-D24-GMCSF. Of the 16 radiologically evaluable patients, 2 had complete responses, 1 had a minor response, and 5 had disease stabilization. Responses were frequently seen in injected and noninjected tumors. Treatment was well tolerated and resulted in the induction of both tumor-specific and virus-specific immunity as measured by ELISPOT and pentamer analysis. This is the first time that oncolytic virus-mediated antitumor immunity has been shown in humans. Ad5-D24-GMCSF is promising for further clinical testing.

Expression of survivin detected by immunohistochemistry in the cytoplasm and in the nucleus is associated with prognosis of leiomyosarcoma and synovial sarcoma patients

Background

Survivin, a member of the inhibitor of apoptosis-protein family suppresses apoptosis and regulates cell division. It is strongly overexpressed in the vast majority of cancers. We were interested if survivin detected by immunohistochemistry has prognostic relevance especially for patients of the two soft tissue sarcoma entities leiomyosarcoma and synovial sarcoma.

Methods

Tumors of leiomyosarcoma (n = 24) and synovial sarcoma patients (n = 26) were investigated for their expression of survivin by immunohistochemistry. Survivin expression was assessed in the cytoplasm and the nucleus of tumor cells using an immunoreactive scoring system (IRS).

Results

We detected a survivin expression (IRS > 2) in the cytoplasm of 20 leiomyosarcomas and 22 synovial sarcomas and in the nucleus of 12 leiomyosarcomas and 9 synovial sarcomas, respectively. There was no significant difference between leiomyosarcoma and synovial sarcoma samples in their cytoplasmic or nuclear expression of survivin. Next, all sarcoma patients were separated in four groups according to their survivin expression in the cytoplasm and in the nucleus: group 1: negative (IRS 0 to 2); group 2: weak (IRS 3 to 4); group 3: moderate (IRS 6 to 8); group 4: strong (IRS 9 to 12). In a multivariate Cox's regression hazard analysis survivin expression detected in the cytoplasm or in the nucleus was significantly associated with overall survival of patients in group 3 (RR = 5.7; P = 0.004 and RR = 5.7; P = 0.022, respectively) compared to group 2 (reference). Patients whose tumors showed both a moderate/strong expression of survivin in the cytoplasm and a moderate expression of survivin in the nucleus (in both compartments IRS ≥ 6) possessed a 24.8-fold increased risk of tumor-related death (P = 0.003) compared to patients with a weak expression of survivin both in the cytoplasm and in the nucleus.

Conclusion

Survivin protein expression in the cytoplasma and in the nucleus detected by immunohistochemistry is significantly associated with prognosis of leiomyosarcoma and synovial sarcoma patients.

Learning about cancer from frogs: analysis of mitotic spindles in Xenopus egg extracts

The mitotic spindle is responsible for correctly segregating chromosomes during cellular division. Disruption of this process leads to genomic instability in the form of aneuploidy, which can contribute to the development of cancer. Therefore, identification and characterization of factors that are responsible for the assembly and regulation of the spindle are crucial. Not only are these factors often altered in cancer, but they also serve as potential therapeutic targets. Xenopus egg extract is a powerful tool for studying spindle assembly and other cell cycle-related events owing, in large part, to the ease with which protein function can be manipulated in the extract. Importantly, the spindle factors that have been characterized in egg extract are conserved in human spindle assembly. In this review, we explain how the extract is prepared and manipulated to study the function of individual factors in spindle assembly and the spindle checkpoint. Furthermore, we provide examples of several spindle factors that have been defined functionally using the extract system and discuss how these factors are altered in human cancer.

Induced epigenetic modifications of the promoter chromatin silence survivin and inhibit tumor growth

Anti-apoptotic survivin is over-expressed in a variety of human carcinomas and is considered as a therapeutic target in cancers. Suppression of survivin mRNA by RNAi and anti-sense nucleotides has proved to be a powerful anti-tumor therapy in both animal models and human investigations. In this communication, we tested an alternative approach to silence survivin by knocking down its gene transcription through a short methylated oligonucleotide (SurKex) that is complementary to the survivin gene promoter. Treatment of NCI-H460 cells with SurKex significantly suppressed the production of survivin mRNA and its oncoprotein. DNA bisulfite sequencing showed that SurKex induced site-specific de novo CpG methylation in the complementary region of survivin promoter. Chromatin immunoprecipitation assay also demonstrated that SurKex induced histone hypermethylation at histone H3K9 and H3K27 as well as deacetylation of histone H4 in the same regulatory region. SurKex remarkably inhibited tumor growth in nude mice bearing xenograft tumors. This study demonstrates that the synthetic methylated oligonucleotide SurKex inhibits tumor growth by silencing the survivin gene using a mechanism of altering the epigenotype in the survivin promoter. Thus, targeted epigenetic modification in the gene promoter may offer a new general strategy to silence tumor-related genes in tumor therapy.

Identification of a small-molecule inhibitor of the interaction between Survivin and Smac/DIABLO

The protein Survivin is selectively overexpressed in a variety of cancers, but not in normal tissues. It has been reported to be involved in cell survival and cell division. However, the molecular mechanisms involved in its function are not clear, although several binding partner proteins have been proposed to date. Here, we report the identification of a novel small molecule Survivin antagonist, which disrupts the Survivin-Smac/DIABLO interaction in cells. In order to identify Survivin-directed antagonists, we developed a high-throughput screening system based on AlphaScreen technology, which allows the identification of small molecules with the ability to inhibit the interaction of Survivin with Smac/DIABLO or INCENP in vitro. We screened chemical libraries, generated in-house, using this system and identified a 5-deazaflavin analog (compound 1) as a hit compound that selectively inhibited the interaction of Survivin with Smac/DIABLO but not INCENP. In cultured cells, compound 1 abrogated the formation of the complex between Survivin and Smac/DIABLO. In addition, this compound was able to sensitize cultured cells to doxorubicin-mediated DNA damage stress and synergistically enhance apoptotic cell death. Thus, the small-molecule inhibitor described here may serve as a proof-of-principle agent for discriminating between the multiple functions of Survivin.

LCK, survivin and PI-3K in the molecular biomarker profiling of oral lichen planus and oral squamous cell carcinoma

T cell signaling is critical in oral lichen planus (OLP) based on the pathogenesis of this chronic inflammatory autoimmune mucocutaneous lesion. Lck plays a key role in T cell signaling; ultimately this signaling affects other targets such as PI-3K. Excessive activity in PI-3K inhibits apoptosis and promotes uncontrolled cell growth. Molecular biomarker profiling in OLP, Chronic Interface Mucosities (CIM), Epithelial Dysplasia (EpD) and Oral Squamous Cell Carcinoma (SCCA) with application of the principle of biomarker voting may represent a new frontier in the diagnosis, assessment and the arguable debate of OLP transformation to cancer. The presence of Lck, PI-3K and Survivin, a cancer specific anti-apoptotic protein was assessed, using immunohistochemistry and tissue micro-array on patient samples, in OLP, SCCA, CIM and EpD. Lck expression was very high in 78.6 % of OLP patients compared to 3.7% in SCCA; PI-3K was high in 63% of SCCA, 100% of EpD, and 35.7% OLP cases. Survivin was high in 64.3% of OLP cases, 96.3% of SCCA, and 100% of EpD. CIM cases may be slightly different molecularly to OLP. Taken together, our data suggest that biomarker protein voting can be effectively used to isolate high-risk OLP cases. Specifically, we show data with four remarkable cases demonstrating that molecular factors are predictive of histopathology. We conclude that it is safer to treat OLP as premalignant lesions, to adopt aggressive treatment measure in histopathologic described well and moderately differentiated SCCA, and to monitor progress of these diseases molecularly using individualized auto-proteomic approach. The use of Lck inhibitors in OLP management needs to be investigated in the future.