Protective and proliferative effects of survivin mutant on differentiated neuroblastoma

This research focused on the neuro-proliferation and protective effects of a survivin mutant. The results showed that this protein binds to microtubules and induces the division and proliferation of neural cells. Furthermore, it protects the neural cells against retinoic acid induced neurotoxicity, activated T-cell apoptosis and oxidative stress.

Survivin mutant protects differentiated dopaminergic SK-N-SH cells against oxidative stress

Oxidative stress is due to an imbalance of antioxidant/pro-oxidant homeostasis and is associated with the progression of several neurological diseases, including Parkinson’s and Alzheimer’s disease and amyotrophic lateral sclerosis. Furthermore, oxidative stress is responsible for the neuronal loss and dysfunction associated with disease pathogenesis. Survivin is a member of the inhibitors of the apoptosis (IAP) family of proteins, but its neuroprotective effects have not been studied. Here, we demonstrate that SurR9-C84A, a survivin mutant, has neuroprotective effects against H2O2-induced neurotoxicity. Our results show that H2O2 toxicity is associated with an increase in cell death, mitochondrial membrane depolarisation, and the expression of cyclin D1 and caspases 9 and 3. In addition, pre-treatment with SurR9-C84A reduces cell death by decreasing both the level of mitochondrial depolarisation and the expression of cyclin D1 and caspases 9 and 3. We further show that SurR9-C84A increases the antioxidant activity of GSH-peroxidase and catalase, and effectively counteracts oxidant activity following exposure to H2O2. These results suggest for the first time that SurR9-C84A is a promising treatment to protect neuronal cells against H2O2-induced neurotoxicity.

Nanoformulated cell-penetrating survivin mutant and its dual actions

In this study, we investigated the differential actions of a dominant-negative survivin mutant (SurR9-C84A) against cancerous SK-N-SH neuroblastoma cell lines and differentiated SK-N-SH neurons. In both the cases, the mutant protein displayed dual actions, where its effects were cytotoxic toward cancerous cells and proliferative toward the differentiated neurons. This can be explained by the fact that tumorous (undifferentiated SK-N-SH) cells have a high endogenous survivin pool and upon treatment with mutant SuR9-C84A causes forceful survivin expression. These events significantly lowered the microtubule dynamics and stability, eventually leading to apoptosis. In the case of differentiated SK-N-SH neurons that express negligible levels of wild-type survivin, the mutant indistinguishably behaved in a wild-type fashion. It also favored cell-cycle progression, forming the chromosome-passenger complex, and stabilized the microtubule-organizing center. Therefore, mutant SurR9-C84A represents a novel therapeutic with its dual actions (cytotoxic toward tumor cells and protective and proliferative toward neuronal cells), and hence finds potential applications against a variety of neurological disorders. In this study, we also developed a novel poly(lactic-co-glycolic acid) nanoparticulate formulation to surmount the hurdles associated with the delivery of SurR9-C84A, thus enhancing its effective therapeutic outcome.

Targeting survivin in cancer : patent review

Importanceof 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.

Nanoformulated mutant SurR9-C84A: a possible key for alzheimer's and its associated inflammation

PURPOSE: Alzheimer's disease (AD) is one of the untreatable neurodegenerative diseases characterised by the pathologic amyloid plaque deposition and inflammation. The aim of this study is to evaluate the neuroprotective effects of nanoformulated SurR9-C84A, a survivin mutant belonging to the inhibitors of the apoptosis (IAP) protein family. The effect of SurR9-C84A was studied against the β-amyloid toxicity and various inflammatory insults in the differentiated SK-N-SH neurons. METHOD: SurR9-C84A loaded poly(lactic-co-glycolic acid) nanoparticles were prepared following the modified double emulsion technique. The neuroprotective effect of SurR9-C84A was evaluated against the amyloid-β (Aβ) peptide fragment, N-methyl-D-aspartate (NMDA) toxicity and the inflammatory assaults. To mimic the in vivo situation, a co-culture of neurons and microglia was also studied to validate these results. RESULTS: SurR9-C84A treatments showed improved neuronal health following Aβ, and NMDA toxicity in addition to inflammatory insults induced in mono and co-cultures. The neuroprotective effect was evident with the reduced neuronal death, accelerated expression of neuronal integrity markers (neurofilaments, beta-tubulin III etc.,) and the neuroprotective ERK/MAPK signalling. CONCLUSION: The current results demonstrated that the SurR9-C84A nanoformulation was very effective in rescuing the neurons and holds a potential future application against AD.

Effects of survivin antagonists of growth of established tumors and B7-1 immunogene therapy

Background: Survivin, a member of the inhibitor of apoptosis (IAP) protein family, is detectable in most types of cancer, and its presence is associated with a poor prognosis. We determined the effects of gene-based therapies that inhibit survivin function in a mouse tumor model. Methods: Using five to six mice per treatment group, we injected tumors derived from mouse EL-4 thymic lymphoma cells with plasmids encoding antisense survivin, a dominant-negative mutant survivin, and the T-cell costimulator B7-1. Expression of endogenous survivin and the proteins encoded by the injected plasmids were examined by immunohistochemical staining of tumor sections and by western blot and flow cytometry analyses of isolated tumor cells. Tumor growth, the generation of antitumor cytotoxic T-lymphocyte (CTL) activity, apoptosis, and the contribution of leukocyte subsets to antitumor activity were measured. All statistical tests were two-sided. Results: Large (1.0-cm diameter) tumors had approximately 10-fold more survivin than small (0.2-cm diameter) tumors. At 28 days after injection, antisense and dominant-negative mutant survivin plasmids statistically significantly inhibited the growth of both small (P = .006 and P = .0018, respectively) and large (P<.001 for both plasmids) EL-4 tumors compared with tumors injected with empty plasmid. The growth of large tumors was further inhibited by intratumoral injection with antisense survivin and B7-1 (P = .004); thus, inhibition of survivin expression renders large tumors susceptible to B7-1-mediated immunotherapy. Mice whose tumors were completely eradicated by injection of B7-1 remained tumor free for 26 days after re-injection with EL-4 cells (when the experiment ended). Compared with tumors injected with empty plasmid, tumors injected with survivin-based plasmids had increased apoptosis, and animals bearing such tumors generated more antitumor CTLs. Conclusion: Intratumoral injection of plasmids that block survivin expression and stimulate the generation of tumor-specific CTLs may be beneficial for the treatment of large lymphomas.

Targeting mutant fibroblast growth factor receptors in cancer

Fibroblast growth factor receptors (FGFRs) play diverse roles in the control of cell proliferation, cell differentiation, angiogenesis and development. Activating the mutations of FGFRs in the germline has long been known to cause a variety of skeletal developmental disorders, but it is only recently that a similar spectrum of somatic FGFR mutations has been associated with human cancers. Many of these somatic mutations are gain-of-function and oncogenic and create dependencies in tumor cell lines harboring such mutations. A combination of knockdown studies and pharmaceutical inhibition in preclinical models has further substantiated genomically altered FGFR as a therapeutic target in cancer, and the oncology community is responding with clinical trials evaluating multikinase inhibitors with anti-FGFR activity and a new generation of specific pan-FGFR inhibitors.

Immunohistochemical detection of survivin in canine lymphoma

Survivin is a member of the family of proteins known as 'inhibitors of apoptosis proteins'. Survivin has a role in cellular decisions concerning division and survival and is frequently expressed in neoplastic cells. The aim of the present study was to investigate immunohistochemically the expression of survivin in normal canine tissues and in canine lymphoma. A representative range of fetal and adult normal tissues as well as biopsy samples from dogs with lymphoma were assembled in tissue arrays. The lymphomas were classified according to the revised Kiel and to the Revised European American Lymphoma - World Health Organization (REAL-WHO) schemes. Polyclonal and monoclonal antisera cross-reactive with canine survivin identified cytoplasmic expression of the molecule in a broad range of normal canine cells. The same reagents demonstrated cytoplasmic labelling of more than 5% of cells in all 83 lymphoma samples tested with polyclonal antiserum and in 67 of 82 (82%) of samples tested with monoclonal antiserum. Survivin was expressed by a wide range of canine lymphoma subtypes, but the expression of this molecule in normal canine tissues must be considered if novel therapies targeting survivin are applied to the management of canine lymphoma. © 2010 Elsevier Ltd.

Sensitivity to the MEK inhibitor E6201 in melanoma cells is associated with mutant BRAF and wildtype PTEN status

BACKGROUND: Melanoma is the most lethal form of skin cancer, but recent advances in molecularly targeted agents against the Ras/Raf/MAPK pathway demonstrate promise as effective therapies. Despite these advances, resistance remains an issue, as illustrated recently by the clinical experience with vemurafenib. Such acquired resistance appears to be the result of parallel pathway activation, such as PI3K, to overcome single-agent inhibition. In this report, we describe the cytotoxicity and anti-tumour activity of the novel MEK inhibitor, E6201, in a broad panel of melanoma cell lines (n = 31) of known mutational profile in vitro and in vivo. We further test the effectiveness of combining E6201 with an inhibitor of PI3K (LY294002) in overcoming resistance in these cell lines. RESULTS: The majority of melanoma cell lines were either sensitive (IC50 < 500 nM, 24/31) or hypersensitive (IC50 < 100 nM, 18/31) to E6201. This sensitivity correlated with wildtype PTEN and mutant BRAF status, whereas mutant RAS and PI3K pathway activation were associated with resistance. Although MEK inhibitors predominantly exert a cytostatic effect, E6201 elicited a potent cytocidal effect on most of the sensitive lines studied, as evidenced by Annexin positivity and cell death ELISA. Conversely, E6201 did not induce cell death in the two resistant melanoma cell lines tested. E6201 inhibited xenograft tumour growth in all four melanoma cell lines studied to varying degrees, but a more pronounced anti-tumour effect was observed for cell lines that previously demonstrated a cytocidal response in vitro. In vitro combination studies of E6201 and LY294002 showed synergism in all six melanoma cell lines tested, as defined by a mean combination index < 1. CONCLUSIONS: Our data demonstrate that E6201 elicits a predominantly cytocidal effect in vitro and in vivo in melanoma cells of diverse mutational background. Resistance to E6201 was associated with disruption of PTEN and activation of downstream PI3K signalling. In keeping with these data we demonstrate that co-inhibition of MAPK and PI3K is effective in overcoming resistance inherent in melanoma.

A tumour-derived mutant allele of XRCC2 preferentially suppresses homologous recombination at DNA replication forks

Homologous recombination repair (HRR) is required for both the repair of DNA double strand breaks (DSBs) and the maintenance of the integrity of DNA replication forks. To determine the effect of a mutant allele of the RAD51 paralog XRCC2 (342delT) found in an HRR-defective tumour cell line, 342delT was introduced into HRR proficient cells containing a recombination reporter substrate. In one set of transfectants, expression of 342delT conferred sensitivity to thymidine and mitomycin C and suppressed HRR induced at the recombination reporter by thymidine but not by DSBs. In a second set of transfectants, the expression of 342delT was accompanied by a decreased level of the full-length XRCC2. These cells were defective in the induction of HRR by either thymidine or DSBs. Thus 342delT suppresses recombination induced by thymidine in a dominant negative manner while recombination induced by DSBs appears to depend upon the level of XRCC2 as well as the expression of the mutant XRCC2 allele. These results suggest that HRR pathways responding to stalled replication forks or DSBs are genetically distinguishable. They further suggest a critical role for XRCC2 in HRR at replication forks, possibly in the loading of RAD51 onto gapped DNA.

Facile mutant identification via a single parental backcross method and application of whole genome sequencing based mapping pipelines

Forward genetic screens have identified numerous genes involved in development and metabolism, and remain a cornerstone of biological research. However, to locate a causal mutation, the practice of crossing to a polymorphic background to generate a mapping population can be problematic if the mutant phenotype is difficult to recognize in the hybrid F2 progeny, or dependent on parental specific traits. Here in a screen for leaf hyponasty mutants, we have performed a single backcross of an Ethane Methyl Sulphonate (EMS) generated hyponastic mutant to its parent. Whole genome deep sequencing of a bulked homozygous F2 population and analysis via the Next Generation EMS mutation mapping pipeline (NGM) unambiguously determined the causal mutation to be a single nucleotide polymorphisim (SNP) residing in HASTY, a previously characterized gene involved in microRNA biogenesis. We have evaluated the feasibility of this backcross approach using three additional SNP mapping pipelines; SHOREmap, the GATK pipeline, and the samtools pipeline. Although there was variance in the identification of EMS SNPs, all returned the same outcome in clearly identifying the causal mutation in HASTY. The simplicity of performing a single parental backcross and genome sequencing a small pool of segregating mutants has great promise for identifying mutations that may be difficult to map using conventional approaches.