Interleukin enhancer-binding factor 3/NF110 is a target of YM155, a suppressant of survivin

Overview of role of survivin in cancer: expression, regulation, functions, and its potential as a therapeutic target

Survivin holds significant importance as a member of the inhibitor of apoptosis protein (IAP) family due to its predominant expression in tumours rather than normal terminally differentiated adult tissues. The high expression level of survivin in tumours is closely linked to chemotherapy resistance, heightened tumour recurrence, and increased tumour aggressiveness and serves as a negative prognostic factor for cancer patients. Consequently, survivin has emerged as a promising therapeutic target for cancer treatment. In this review, we delve into the various biological characteristics of survivin in cancers and its pivotal role in maintaining immune system homeostasis. Additionally, we explore different therapeutic strategies aimed at targeting survivin.

Pioneering 4,11-Dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium Compounds as Promising Survivin Inhibitors by Targeting ILF3/NF110 for Cancer Therapy

Survivin is a novel attractive target for cancer therapy; however, it is considered undruggable because it lacks enzymatic activities. Herein, we describe our efforts toward the discovery of a novel series of 4,11-dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium derivatives as survivin inhibitors by targeting ILF3/NF110. Intensive structural modifications led us to identify a lead compound AQIM-I, which remarkably inhibited nonsmall cell lung cancer cells A549 with an IC50 value of 9 nM and solid tumor cell proliferation with more than 700-fold selectivity against human normal cells. Further biological studies revealed that compound AQIM-I significantly inhibited survivin expression and colony formation and induced ROS production, apoptosis, cell cycle arrest, DNA damage, and autophagy. Furthermore, the promoter-luciferase reporter assay showed that AQIM-I attenuated the survivin promoter activity enhanced by the overexpression of ILF3/NF110 in a concentration-dependent manner, and specific binding (KD = 163 nM) of AQIM-I to ILF3/NF110 was detected by surface plasmon resonance.

Oncogenic RAS promotes MYC protein stability by upregulating the expression of the inhibitor of apoptosis protein family member Survivin

The small GTPase KRAS is frequently mutated in pancreatic cancer and its cooperation with the transcription factor MYC is essential for malignant transformation. The key to oncogenic KRAS and MYC working together is the stabilization of MYC expression due to KRAS activating the extracellular signal-regulated kinase 1/2, which phosphorylates MYC at serine 62 (Ser 62). This prevents the proteasomal degradation of MYC while enhancing its transcriptional activity. Here, we identify how this essential signaling connection between oncogenic KRAS and MYC expression is mediated by the inhibitor of apoptosis protein family member Survivin. This discovery stemmed from our finding that Survivin expression is downregulated upon treatment of pancreatic cancer cells with the KRAS^G12C inhibitor Sotorasib. We went on to show that oncogenic KRAS increases Survivin expression by activating extracellular signal-regulated kinase 1/2 in pancreatic cancer cells and that treating the cells either with siRNAs targeting Survivin or with YM155, a small molecule that potently blocks Survivin expression, downregulates MYC and strongly inhibited their growth. We further determined that Survivin protects MYC from degradation by blocking autophagy, which then prevents cellular inhibitor of protein phosphatase 2A from undergoing autophagic degradation. Cellular inhibitor of protein phosphatase 2A, by inhibiting protein phosphatase 2A, helps to maintain MYC phosphorylation at Ser 62, thereby ensuring its cooperation with oncogenic KRAS in driving cancer progression. Overall, these findings highlight a novel role for Survivin in mediating the cooperative actions of KRAS and MYC during malignant transformation and raise the possibility that targeting Survivin may offer therapeutic benefits against KRAS-driven cancers.

A Proximity biotinylation assay with a host protein bait reveals multiple factors modulating enterovirus replication

As ultimate parasites, viruses depend on host factors for every step of their life cycle. On the other hand, cells evolved multiple mechanisms of detecting and interfering with viral replication. Yet, our understanding of the complex ensembles of pro- and anti-viral factors is very limited in virtually every virus-cell system. Here we investigated the proteins recruited to the replication organelles of poliovirus, a representative of the genus Enterovirus of the Picornaviridae family. We took advantage of a strict dependence of enterovirus replication on a host protein GBF1, and established a stable cell line expressing a truncated GBF1 fused to APEX2 peroxidase that effectively supported viral replication upon inhibition of the endogenous GBF1. This construct biotinylated multiple host and viral proteins on the replication organelles. Among the viral proteins, the polyprotein cleavage intermediates were overrepresented, suggesting that the GBF1 environment is linked to viral polyprotein processing. The proteomics characterization of biotinylated host proteins identified multiple proteins previously associated with enterovirus replication, as well as more than 200 new factors recruited to the replication organelles. RNA metabolism proteins, many of which normally localize in the nucleus, constituted the largest group, underscoring the massive release of nuclear factors into the cytoplasm of infected cells and their involvement in viral replication. Functional analysis of several newly identified proteins revealed both pro- and anti-viral factors, including a novel component of infection-induced stress granules. Depletion of these proteins similarly affected the replication of diverse enteroviruses indicating broad conservation of the replication mechanisms. Thus, our data significantly expand the knowledge of the composition of enterovirus replication organelles, provide new insights into viral replication, and offer a novel resource for identifying targets for anti-viral interventions.

Effects of YM155 on the proliferation and apoptosis of pulmonary artery smooth muscle cells in a rat model of high pulmonary blood flow-induced pulmonary arterial hypertension

INTRODUCTION

Proliferation and apoptosis of pulmonary artery smooth muscle cells (PASMCs) play an important role in the occurrence and development of pulmonary arterial hypertension (PAH). The purpose of this study was to investigate the effects of survivin inhibitor YM155 on the proliferation and apoptosis of PASMCs in rats with PAH induced by high pulmonary blood flow.

METHODS

Thirty male Sprague-Dawley (SD) rats were randomly divided into control, model, and YM155 intervention groups. A rat model of PAH induced by high pulmonary blood flow was established, and it was confirmed by assessments of right-ventricular pressure (RVP) and right ventricular hypertrophy index (RVHI). Immunohistochemical staining and western blot analysis were used to detect the expression of survivin, and the proliferation and apoptosis of PASMCs. Lastly, the effects of in vivo treatment of YM155 were tested.

RESULTS

The increased expression of survivin mRNA and protein were observed in the model group, accompanied by pulmonary arteriolar wall thickening, lumen stenosis, and perivascular inflammatory cell infiltration. Elevated expression of survivin and pulmonary vascular remodeling were significantly mitigated after YM155 treatment. Specifically, the YM155 intervention group had a significantly lower PASMC proliferation rate and a higher PASMC apoptotic rate.

CONCLUSION

YM155 suppressed PASMC proliferation and promoted PASMC apoptosis by inhibiting survivin expression and thereby reducing pulmonary vascular remodeling in high pulmonary blood flow-induced PAH in vivo.

Functional and Pathogenic Roles of Retroviral Antisense Transcripts

Exogenous retroviruses such as human immunodeficiency virus type 1 (HIV-1), human T-cell leukemia virus type 1 (HTLV-1) and bovine leukemia virus (BLV) can cause various diseases including immunodeficiency, inflammatory diseases and hematologic malignancies. These retroviruses persistently infect their hosts. Therefore, they need to evade host immune surveillance. One way in which these viruses might avoid immune detection is to utilize functional RNAs, rather than proteins, for certain activities, because RNAs are not recognized by the host immune system. HTLV-1 encodes the HTLV-1 bZIP factor (HBZ) gene in the antisense strand of the provirus. The HBZ protein is constantly expressed in HTLV-1 carriers and patients with adult T-cell leukemia-lymphoma, and it plays critical roles in pathogenesis. However, HBZ not only encodes this protein, but also functions as mRNA. Thus, HBZ gene mRNA is bifunctional. HIV-1 and BLV also encode long non-coding RNAs as antisense transcripts. In this review, we reshape our current understanding of how these antisense transcripts function and how they influence disease pathogenesis.

USP32 confers cancer cell resistance to YM155 via promoting ER-associated degradation of solute carrier protein SLC35F2

Background: The most commonly preferred chemotherapeutic agents to treat cancers are small-molecule drugs. However, the differential sensitivity of various cancer cells to small molecules and untargeted delivery narrow the range of potential therapeutic applications. The mechanisms responsible for drug resistance in a variety of cancer cells are also largely unknown. Several deubiquitinating enzymes (DUBs) are the main determinants of drug resistance in cancer cells.

Methods: We used CRISPR-Cas9 to perform genome-scale knockout of the entire set of genes encoding ubiquitin-specific proteases (USPs) and systematically screened for DUBs resistant to the clinically evaluated anticancer compound YM155. A series of in vitro and in vivo experiments were conducted to reveal the relationship between USP32 and SLC35F2 on YM155-mediated DNA damage in cancer cells.

Results: CRISPR-based dual-screening method identified USP32 as a novel DUB that governs resistance for uptake of YM155 by destabilizing protein levels of SLC35F2, a solute-carrier protein essential for the uptake of YM155. The expression of USP32 and SLC35F2 was negatively correlated across a panel of tested cancer cell lines. YM155-resistant cancer cells in particular exhibited elevated expression of USP32 and low expression of SLC35F2.

Conclusion: Collectively, our DUB-screening strategy revealed a resistance mechanism governed by USP32 associated with YM155 resistance in breast cancers, one that presents an attractive molecular target for anti-cancer therapies. Targeted genome knockout verified that USP32 is the main determinant of SLC35F2 protein stability in vitro and in vivo, suggesting a novel way to treat tumors resistant to small-molecule drugs.

Survivin as a biological biomarker for diagnosis and therapy

Introduction: Survivin (SVN) is a member of the inhibitor of apoptosis (IAP) protein family that promotes cellular proliferation and inhibits apoptosis. Overexpression of SVN is associated with autoimmune disease, hyperplasia, and tumors and can be used as a biomarker in these diseases. SVN is widely recognized as a tumor-associated antigen (TAA) and has become an important target for cancer diagnosis and treatment.Areas covered: We reviewed SVN research progress from the PubMed and clinical trials focused on SVN from https://clinicaltrials.gov since 2000 and anticipate future developments in the field. The trials reviewed cover various modalities including diagnostics for early detection and disease progression, small molecule inhibitors of the SVN pathway and immunotherapy targeting SVN epitopes.Expert opinion: The most promising developments involve anti-SVN immunotherapy, with several therapeutic SVN vaccines under evaluation in phase I/II trials. SVN is an important new immune-oncology target that expands the repertoire of individualized combination treatments for cancer.

Inhibition of Sp1-mediated survivin and MCL1 expression cooperates with SLC35F2 and myeloperoxidase to modulate YM155 cytotoxicity to human leukemia cells

Although YM155 is reported to suppress survivin (also known as BIRC5) expression in cancer cells, its cytotoxic mechanism in human acute myeloid leukemia (AML) cells has not been clearly resolved. In this study, we analyzed the mechanistic pathways that modulate the sensitivity of human AML U937 and HL-60 cells to YM155. YM155 induced apoptosis in AML cells, which was characterized by p38 MAPK phosphorylation and downregulation of survivin and MCL1 expression. Phosphorylated p38 MAPK causes autophagy-mediated Sp1 degradation, thereby inhibiting the transcription of survivin and MCL1. The reduction of survivin and MCL1 levels further facilitated Sp1 protein degradation through autophagy. The restoration of Sp1, survivin, or MCL1 expression protected U937 and HL-60 cells from YM155-mediated cytotoxicity. U937 and HL-60 cells were continuously exposed to hydroquinone (HQ) to generate U937/HQ and HL-60/HQ cells, which showed increased SLC35F2 expression. The increase in SLC35F2 expression led to an increase in the sensitivity of U937/HQ cells to YM155-mediated cytotoxicity, whereas no such effect was observed in HL-60/HQ cells. Of note, myeloperoxidase (MPO) activity in HL-60 and HL-60/HQ cells enhanced YM155 cytotoxicity in these cells, and the enforced expression of MPO also increased the sensitivity of U937 cells to YM155. Taken together, we conclude that p38 MAPK-modulated autophagy inhibits Sp1-mediated survivin and MCL1 expression, which, in turn, leads to the death of U937 and HL-60 cells following YM155 treatment. In addition, our data indicate that SLC35F2 increases the sensitivity of U937 cells to YM155-mediated cytotoxicity, whereas MPO enhances YM155 cytotoxicity in U937 and HL-60 cells.

Ym155 Induces Oxidative Stress-Mediated DNA Damage and Cell Cycle Arrest, and Causes Programmed Cell Death in Anaplastic Thyroid Cancer Cells

Anaplastic thyroid cancer (ATC) is one of the most lethal malignancies with a median survival time of about 4 months. Currently, there is no effective treatment, and the development of new therapies is an important and urgent issue for ATC patients. YM155 is a small molecule that was identified as the top candidate in a high-throughput screen of small molecule inhibitors performed against a panel of ATC cell lines by the National Cancer Institute. However, there were no follow-up studies investigating YM155 in ATC. Here, we determined the effects of YM155 on ATC and human primary benign thyroid cell (PBTC) survival with alamarBlue assay. Our data show that YM155 inhibited proliferation of ATC cell lines while sparing normal thyroid cells, suggesting a high therapeutic window. YM155-induced DNA damage was detected by measuring phosphorylation of γ-H2AX as a marker for DNA double-strand breaks. The formamidopyrimidine-DNA glycosylase (FPG)-modified alkaline comet assay in conjunction with reactive oxygen species (ROS) assay and glutathione (GSH)/glutathione (GSSG) assay suggests that YM155-mediated oxidative stress contributes to DNA damage. In addition, we provide evidence that YM155 causes cell cycle arrest in S phase and in the G2/M transition and causes apoptosis, as seen with flow cytometry. In this study, we show for the first time the multiple effects of YM155 in ATC cells, furthering a potential therapeutic approach for ATC.

Effect of Sepatronium Bromide (YM-155) on DNA Double-Strand Breaks Repair in Cancer Cells

Survivin, as an antiapoptotic protein often overexpressed in cancer cells, is a logical target for potential cancer treatment. By overexpressing survivin, cancer cells can avoid apoptotic cell death and often become resistant to treatments, representing a significant obstacle in modern oncology. A survivin suppressor, an imidazolium-based compound known as YM-155, is nowadays studied as an attractive anticancer agent. Although survivin suppression by YM-155 is evident, researchers started to report that YM-155 is also an inducer of DNA damage introducing yet another anticancer mechanism of this drug. Moreover, the concentrations of YM-155 for DNA damage induction seems to be far lower than those needed for survivin inhibition. Understanding the molecular mechanism of action of YM-155 is of vital importance for modern personalized medicine involving the selection of responsive patients and possible treatment combinations. This review focuses mainly on the documented effects of YM-155 on DNA damage signaling pathways. It summarizes up to date literature, and it outlines the molecular mechanism of YM-155 action in the context of the DNA damage field.

The role of survivin in the progression of pancreatic ductal adenocarcinoma (PDAC) and a novel survivin-targeted therapeutic for PDAC

Treating pancreatic ductal adenocarcinoma (PDAC) remains a major hurdle in the field of oncology. Less than half of patients respond to frontline chemotherapy and the pancreatic tumor microenvironment limits the efficacy of immunotherapeutic approaches. Targeted therapies could serve as effective treatments to enhance the clinical response rate. One potential therapeutic target is survivin, a protein that is normally expressed during embryonic and fetal development and has a critical impact on cell cycle control and apoptosis. In adulthood, survivin is not present in most normal adult cells, but is significantly re-expressed in tumor tissues. In PDAC, elevated survivin expression is correlated with treatment resistance and lower patient survival, although the underlying mechanisms of survivin's action in this type of cancer is poorly understood. Using patient derived xenografts of PDAC and their corresponding primary pancreatic cancer lines (PPCL-46 and PPCL-LM1) possessing increased expression of survivin, we aimed to evaluate the therapeutic response of a novel survivin inhibitor, UFSHR, with respect to survivin expression and the tumorigenic characteristics of PDAC. Cell viability and apoptosis analyses revealed that repressing survivin expression by UFSHR or YM155, a well-known inhibitor of survivin, in PPCLs effectively reduces cell proliferation by inducing apoptosis. Tumor cell migration was also hindered following treatment with YM155 and UFSHR. In addition, both survivin inhibitors, particularly UFSHR, effectively reduced progression of PPCL-46 and PPCL-LM1 tumors, when compared to the untreated cohort. Overall, this study provides solid evidence to support the critical role of survivin in PDAC progression and proposes a novel survivin inhibitor UFSHR that can become an alternative strategy for this type of cancer.

MiR-215-5p inhibits the inflammation injury in septic H9c2 by regulating ILF3 and LRRFIP1

MicroRNAs (miRNAs) are small non-coding RNAs (ncRNAs) playing crucial roles in sepsis-induced diseases, including myocardial inflammation. Nevertheless, the expression pattern and role of miR-215-5p in myocardial inflammation are still un-investigated up to now. The purpose of our study is to further inquire the effect of miR-215-5p on lipopolysaccharide (LPS)-activated inflammation injury in H9c2 cells and the possibly associated mechanisms. First of all, LPS-induced H9c2 cells models were constructed and affirmed via detection of pro-inflammatory factors, the viability and apoptosis. MiR-215-5p was overtly down-regulated in LPS-treated H9c2 cells and miR-215-5p overexpression could suppress the inflammation injury. LRRFIP1 was proved to be the target gene of miR-215-5p and meanwhile, miR-215-5p also targeted ILF3 that experimented to bind to and stabilize LRRFIP1. Final rescue assays confirmed that the overexpression of LRRFIP1 or ILF3 rescued the repressive effect of miR-215-5p up-regulation on the inflammation injury in septic H9c2. Totally, miR-215-5p exerted protective function in the inflammation injury in septic H9c2 via targeting ILF3 and LRRFIP1, suggesting an additional treatment method for sepsis-activated myocardial inflammation.

STAT3 induces G9a to exacerbate HER3 expression for the survival of epidermal growth factor receptor-tyrosine kinase inhibitors in lung cancers

Background

HER3 mediates drug resistance against epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), resulting in tumor relapse in lung cancers. Previously, we demonstrated that EGFR induces HER3 overexpression, which facilitates the formation of cancer stem-like tumorspheres. However, the cellular mechanism through which EGFR regulates HER3 expression remains unclear. We hypothesized that EGFR downstream of STAT3 participates in HER3 expression because STAT3 contributes to cancer stemness and survival of EGFR-TKI resistant cancers.

Methods

First, RNAseq was used to uncover potential genes involved in the formation of lung cancer HCC827-derived stem-like tumorspheres. EGFR-positive lung cancer cell lines, including HCC827, A549, and H1975, were individually treated with a panel containing 172 therapeutic agents targeting stem cell-associated genes to search for potential agents that could be applied against EGFR-positive lung cancers. In addition, gene knockdown and RNAseq were used to investigate molecular mechanisms through which STAT3 regulates tumor progression and the survival in lung cancer.

Results

BBI608, a STAT3 inhibitor, was a potential therapeutic agent that reduced the cell viability of EGFR-positive lung cancer cell lines. Notably, the inhibitory effects of BBI608 were similar with those associated with YM155, an ILF3 inhibitor. Both compounds reduced G9a-mediated HER3 expression. We also demonstrated that STAT3 upregulated G9a to silence miR-145-5p, which exacerbated HER3 expression in this study.

Conclusions

The present study revealed that BBI608 could eradicate EGFR-positive lung cancers and demonstrated that STAT3 enhanced the expression of HER3 through miR-145-5p repression by G9a, indicating that STAT3 is a reliable therapeutic target against EGFR-TKI-resistant lung cancers.

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.

Early Cellular Responses of Prostate Carcinoma Cells to Sepantronium Bromide (YM155) Involve Suppression of mTORC1 by AMPK

The imidazolium compound YM155, first discovered as a potent inhibitor of Survivin, effectively kills many carcinomas in preclinical models. However, the upstream signaling mechanism triggered by YM155 remains unclear. Here we studied early signaling responses in vitro in prostate and renal cancer cell lines in a dose-dependent manner. We found that YM155 rapidly activates the retinoblastoma protein, correlating with the loss of expression of all three Cyclin Ds. Using Western blot, various selective chemical inhibitors and q-PCR, we show that YM155-mediated decrease in protein levels of Cyclin Ds, Survivin and Mcl-1 is independent of transcription or proteasomal control mechanisms. Moreover, we provide the first evidence that YM155 changes the phosphorylation status of known mTOR-target proteins involved in translational control, namely ribosomal protein S6 (rS6) and 4E-BP1. Our data support that YM155 achieves this by blocking mTORC1 via the phosphorylation of Raptor at S792 through activated AMPKα (T172). Furthermore, we also used a polysome profile, supporting that YM155 markedly suppresses cap-dependent translation of mRNAs which include Survivin, Cyclin D1 and Mcl-1. We provide the first evidence that YM155 functions as a potent activator of AMPKα, a robust suppressor of mTORC1 and an attenuator of global protein synthesis.

Yin Yang 1 (YY1): Regulation of Survivin and Its Role In Invasion and Metastasis

Despite significant clinical and basic science advancements, cancer remains a devastating disease that affects people of all ages, races, and backgrounds. The pathogenesis of cancer has recently been described to result from eight biological capabilities or hallmarks and two enabling characteristics. These eight hallmarks are: deregulation of cellular energetics, avoiding immune destruction, enabling replicative immortality, inducing angiogenesis, sustaining proliferative signaling, evading growth suppressors, resisting cell death, and activating invasion and metastasis. The enabling characteristics are: genome instability and mutation and tumor-promoting inflammation. Survivin, the fourth most common transcript found in cancer cells, is a protein that is thought to be involved in the enhanced proliferation, survival, and metastasis and possibly other key hallmarks of cancer cells. Understanding how this gene is turned on and off is vitally important for attempt improving cancer management and therapy. Our work has identified a novel transcriptional regulator of survivin called Yin Yang 1 (YY1), which has been observed to activate some gene promoters and repress others and is gaining increasing interest as a target of cancer therapy. Our work shows for the first time that YY1 represses survivin transcription by physically interacting with the survivin promoter. Furthermore, YY1 appears to contribute to basal survivin transcriptional activity, indicating that disruption of its binding may in part contribute to survivin overexpression after cellular stress events including chemotherapy and radiotherapy.

Epigenetic Changes at the Birc5 Promoter Induced by YM155 in Synovial Sarcoma

YM155 is an anti-cancer therapy that has advanced into 11 different human clinical trials to treat various cancers. This apoptosis-inducing therapy indirectly affects the protein levels of survivin (gene: Birc5), but the molecular underpinnings of the mechanism remain largely unknown. Synovial sarcoma is a rare soft-tissue malignancy with high protein expression of survivin. We investigated whether YM155 would be a viable therapeutic option to treat synovial sarcoma. YM155 therapy was applied to human synovial sarcoma cell lines and to a genetically engineered mouse model of synovial sarcoma. We discovered that YM155 exhibited nanomolar potency against human synovial sarcoma cell lines and the treated mice with synovial sarcoma demonstrated a 50% reduction in tumor volume compared to control treated mice. We further investigated the mechanism of action of YM155 by looking at the change of lysine modifications of the histone tails that were within 250 base pairs of the Birc5 promoter. Using chromatin immunoprecipitation (ChIP)-qPCR, we discovered that the histone epigenetic marks of H3K27 for the Birc5 promoter changed upon YM155 treatment. H3K27me3 and H3K27ac increased, but the net result was decreased Birc5/survivin expression. Furthermore, the combination of molecular events resulted in caspase 3/7/8 upregulation and death of the sarcoma cells.

YM155 enhances docetaxel efficacy in ovarian cancer

YM155 (Sepantronium bromide) is a potent small molecule inhibitor of survivin by suppression of survivin expression and shows the promising anticancer activity in many types of cancers. Docetaxel (Taxotere^®) is a member of the taxane drugs used in the treatment of a number of cancers in clinic. Despite the therapeutic efficacy of docetaxel is encouraging, the emergent resistance is an urgent issue. In this study, we investigate the effect of YM155 on docetaxel efficacy in ovarian cancer cells. Our data showed that YM155 actively induced cell growth inhibition, cell cycle arrest and apoptosis with downregualtion of survivin in ovarian cancer cells. Moreover, YM155 increased the intracellular ROS levels, and pretreatment with either NAC or GSH partially reversed the YM155-induced ROS accumulation and apoptosis only in the parental A2780 cells, but not in the resistant A2780/Taxol cells. Furthermore, YM155 enhanced docetaxel efficacy to inhibit the growth and induce apoptosis in ovarian cancer cells. Take together, our results suggested that combination of YM155 and docetaxel may be a feasible strategy for the treatment of ovarian cancer.

Proteins involved in the antioxidant and inflammatory response in rutin-treated human skin fibroblasts exposed to UVA or UVB irradiation

BACKGROUND

Rutin, due to its polyphenolic structure, has antioxidant properties and can be used as a cytoprotective compound against UV-induced effects on skin cells.

OBJECTIVE

The aim of this study was to examine the effect of rutin on proteomic profile in human skin fibroblasts irradiated with UV dose that induces apoptosis.

METHODS

Proteome analysis based on the results obtained by the QExactive OrbiTrap mass spectrometer.

RESULTS

Results show that rutin treatment more strongly protects against UVA-induced rather than UVB-induced increases in the total expression of proteins involved in antioxidant (such as SOD, TrxR, and Prxs 1/2) and inflammatory response (e.g., IL-17F, PAK2, and YWHAZ). However, in the case of UVB-irradiated cells, rutin additionally enhances the levels of disulfide-isomerase - an enzyme that is responsible for the formation and breakage of disulfide bonds. Moreover, UVB radiation promotes rutin-Keap1 adduct formation, which leads to the activation of Nrf2, a factor that is responsible for the synthesis of cytoprotective proteins. Furthermore, rutin partially prevents UV-induced apoptosis by restoring the physiological levels of p53, cytochrome c, and cell cycle and apoptosis regulator protein 2 that were increased following irradiation.

CONCLUSION

In conclusion, our results show that rutin effectively prevents UV-induced damages associated with proinflammatory and prooxidative activity and protects cells against apoptosis.

Discovery and cellular stress pathway analysis of 1,4-naphthoquinone derivatives with novel, highly potent broad-spectrum anticancer activity

BACKGROUND

Chemotherapy and targeted therapies have made important strides in cancer treatment yet they often fail and new therapies are still needed. Here, we employed a phenotypic screen to identify and analyze the mechanism of action of novel small molecules that interfere with critical pathways involved in tumor cell growth, using chemoresistant A375 melanoma cells as a model.

METHODS

Cell culture studies were performed in ATCC-recommended media. Compounds, and compound libraries were obtained from Boston University or purchased commercially. Effects on A375 cell viability, proliferation and morphology were determined by Celigo Image Cytometer and viability staining. Anticancer activity of the lead compound was tested in a xenograft nude mouse model. Signaling and cell death pathways were analyzed by SDS-PAGE and immunoblotting, and/or fluorescence microscopy.

RESULTS

After evaluating 4477 compounds, one hit compound CB533 was identified that caused significant reduction of A375 cell growth. CB533 is an unexplored 1,4-naphthoquinone (NQ) derivative which unlike 1,4-NQ, induced rapid cell death without generating reactive oxygen species (ROS). Structure-activity relationship analysis showed that a pyrrolidine in the 1,4-NQ nucleus in lead compound Pyr-1 yielded optimal activity. CB533 and Pyr-1 had growth-suppressing effects on a large variety of chemotherapy-resistant cancer cell lines in the nano to picomolar range. Pyr-1 also significantly reduced growth of MDA-MB-231 breast cancer cells in nude mice. Pyr-1 rapidly induced activation of major stress pathways and autophagy, which was efficiently blocked by ERK, and somewhat by PI3K inhibitors.

CONCLUSION

CB533 and lead Pyr-1 represent novel broad-spectrum, anticancer compounds that are up to 1000-fold more potent than plumbagin, a natural 1,4-NQ with known anticancer activity. Since the growth suppression activities of CB533 and Pyr-1 are unaffected by the chemotherapy resistance of cancer cells, these compounds have promising therapeutic potential. The pyrrolidine in the 3 position of the 1,4-NQ nucleus of Pyr-1 is a critical component of the pharmacophore. Pyr-1-induced cellular stress was mediated by an ERK, and to a lesser extent by an AKT-dependent pathway without involving apoptosis. Our data suggest that Pyr-1 derives its greatly enhanced antitumor activity via mimicking ROS-induced stress signaling without generating ROS, and likely committing cells to autophagy.

Inhibitor of Apoptosis Proteins (IAPs) are commonly dysregulated in GIST and can be pharmacologically targeted to enhance the pro-apoptotic activity of imatinib

Gastrointestinal stromal tumors (GIST) exhibit a strong oncogenic dependency on KIT and KIT inhibitors confer long lasting disease stabilization in the majority of patients. Nonetheless, KIT inhibition alone does not cure GIST as a subset of GIST cells evade apoptosis and eventually develop resistance. Inhibitors of Apoptosis Proteins (IAPs) may confer resistance to drug-induced apoptosis. We observed that the mRNA and protein of IAPs XIAP (BIRC4) and survivin (BIRC5) were highly expressed in primary GIST tumors and cell line models. Amplification of the respective gene loci (BIRC2, BIRC3, BIRC4, BIRC5) was detected in 47% of GIST studied by SNP arrays. Whole exome analyses revealed a mutation of SMAC(DIABLO) in a heavily pretreated patient. Both, survivin (rank 62-92/11.194 tested proteins) and XIAP (rank 106-557/11.194) were found to be essential proteins for survival in a synthetic lethality screen. Expression of XIAP and survivin decreased upon KIT inhibition and may play a role in KIT-regulated pro-survival signaling. SMAC-mimetic treatment with LCL161 and TL32711 reduced cIAP1 and XIAP expression. Survivin inhibitor YM155 lead to transcriptional repression of BIRC5/survivin (YM155) and induced apoptosis. Combinational treatment with KIT inhibitors (imatinib, regorafenib) enhanced the proapoptotic effect. These findings support the combination of KIT inhibition with IAP antagonists in GIST.

EGFR-mediated interleukin enhancer-binding factor 3 contributes to formation and survival of cancer stem-like tumorspheres as a therapeutic target against EGFR-positive non-small cell lung cancer

OBJECTIVES

YM155, an inhibitor of interleukin enhancer-binding factor 3 (ILF3), significantly suppresses cancer stemness property, implying that ILF3 contributes to cell survival of cancer stem cells. However, the molecular function of ILF3 inhibiting cancer stemness remains unclear. This study aimed to uncover the potential function of ILF3 involving in cell survival of epidermal growth factor receptor (EGFR)-positive lung stem-like cancer, and to investigate the potential role to improve the efficacy of anti-EGFR therapeutics.

MATERIALS AND METHODS

The association of EGFR and ILF3 in expression and regulations was first investigated in this study. Lung cancer A549 cells with deprivation of ILF3 were created by the gene-knockdown method and then RNAseq was applied to identify the putative genes regulated by ILF3. Meanwhile, HCC827- and A549-derived cancer stem-like cells were used to investigate the role of ILF3 in the formation of cancer stem-like tumorspheres.

RESULTS

We found that EGFR induced ILF3 expression, and YM155 reduced EGFR expression. The knockdown of ILF3 reduced not only EGFR expression in mRNA and protein levels, but also cell proliferation in vitro and in vivo, demonstrating that ILF3 may play an important role in contributing to cancer cell survival. Moreover, the knockdown and inhibition of ILF3 by shRNA and YM155, respectively, reduced the formation and survival of HCC827- and A549-derived tumorspheres through inhibiting ErbB3 (HER3) expression, and synergized the therapeutic efficacy of afatinib, a tyrosine kinase inhibitor, against EGFR-positive A549 lung cells.

CONCLUSION

This study demonstrated that ILF3 plays an oncogenic like role in maintaining the EGFR-mediated cellular pathway, and can be a therapeutic target to improve the therapeutic efficacy of afatinib. Our results suggested that YM155, an ILF3 inhibitor, has the potential for utilization in cancer therapy against EGFR-positive lung cancers.

Synthesis and biological evaluation of novel 2-arylvinyl-substituted naphtho[2,3-d]imidazolium halide derivatives as potent antitumor agents

Two series of novel 2-arylvinyl-naphtho[2,3-d]imidazol-3-ium iodide derivatives and 2-arylvinyl-naphtho[2,3-d]imidazol-3-ium bromide derivatives were designed and synthesized by the structural combination of YM155 with stilbenoids. All compounds were tested for anti-proliferative activity against PC-3, A375 and HeLa human cancer cell lines. Two of the compounds were selected for further investigation: 12b, which showed potent cytotoxicity against the three tested cell lines with IC₅₀ values in the range of 0.06-0.21 μM, and 7l, which displayed excellent selectivity for PC-3 cells with an IC₅₀ of only 22 nM. Western blot analysis results indicated that both 12b and 7l suppress the expression of Bcl-2 and Survivin proteins, which helps induce apoptosis. As determined by the percent of Annexin V-FITC-positive apoptotic cells, 12b was not only significantly more effective than 7l at a concentration of 100 nM in PC-3 cells but also induced apoptosis in a dose-dependent manner with more potency than 7l at a concentration of 1000 nM in A375 cells. Therefore, compound 12b was chosen for further in-depth studies investigating the mechanism of apoptosis. The results showed that it could activate caspase-3, hydrolyze PARP, and even inactivate ERK. Moreover, 12b arrested A375 cells at S phase in a time-dependent and dose-dependent manner, while having a visible effect on microtubule dynamics. In addition, (E)-2-(2-(1H-indol-3-yl)vinyl)-1-benzyl-3-(2-methoxyethyl)-4,9-dioxo-4,9-dihydro-1H-naphtho[2,3-d]imidazol-3-ium bromide (12b) exhibited significant antitumor activity when evaluated in a subcutaneous solid tumor model. Our study reveals that 2-arylvinyl-substituted naphtho[2,3-d]imidazolium scaffolding is a promising new entity for the development of multi-target anticancer drugs.

YM155 exerts potent cytotoxic activity against quiescent (G0/G1) multiple myeloma and bortezomib resistant cells via inhibition of survivin and Mcl-1

YM155, a novel small molecule inhibitor of survivin, shows broad anticancer activity. Here, we have focused on the cytotoxic activity of YM155 against multiple myeloma (MM) including cytokinetically quiescent (G₀/G₁) cells and bortezomib resistant cells. YM155 strongly inhibited the growth of MM cell lines with the IC₅₀ value of below 10 nM. YM155 also showed potent anti-myeloma activity in mouse xenograft model. YM155 suppressed the expression of survivin and rapidly directed Mcl-1 protein for proteasome degradation. YM155 abrogated the interleukin-6-induced STAT3 phosphorylation, subsequently blocked Mcl-1 expression and induced apoptosis in MM cells. Triple-color flow cytometric analysis revealed that YM155 potently induced cell death of MM cells in G₀ phase. Quiescent primary MM cells were also sensitive to YM155. We established bortezomib-resistant MM cell line, U266/BTZR1, which possess a point mutation G322A. YM155 exhibited similar cytotoxic potency against U266/BTZR1 compared with parental cells. Interestingly, survivin expression was markedly elevated in U266/BTZR1 cells. Treatment with YM155 significantly down-regulated this increased survivin and Mcl-1 expression in U266/BTZR1 cells. In conclusion, our data indicate that YM155 exhibits potent cytotoxicity against quiescent (G₀/G₁) MM cells and bortezomib-resistant cells. These unique features of YM155 may be beneficial for the development of new therapeutic strategies to eliminate quiescent MM cells and overcome bortezomib resistance.

Phenotype-driven precision oncology as a guide for clinical decisions one patient at a time

Genomics-driven cancer therapeutics has gained prominence in personalized cancer treatment. However, its utility in indications lacking biomarker-driven treatment strategies remains limited. Here we present a "phenotype-driven precision-oncology" approach, based on the notion that biological response to perturbations, chemical or genetic, in ex vivo patient-individualized models can serve as predictive biomarkers for therapeutic response in the clinic. We generated a library of "screenable" patient-derived primary cultures (PDCs) for head and neck squamous cell carcinomas that reproducibly predicted treatment response in matched patient-derived-xenograft models. Importantly, PDCs could guide clinical practice and predict tumour progression in two n = 1 co-clinical trials. Comprehensive "-omics" interrogation of PDCs derived from one of these models revealed YAP1 as a putative biomarker for treatment response and survival in ~24% of oral squamous cell carcinoma. We envision that scaling of the proposed PDC approach could uncover biomarkers for therapeutic stratification and guide real-time therapeutic decisions in the future.Treatment response in patient-derived models may serve as a biomarker for response in the clinic. Here, the authors use paired patient-derived mouse xenografts and patient-derived primary culture models from head and neck squamous cell carcinomas, including metastasis, as models for high-throughput screening of anti-cancer drugs.

YM155 as an inhibitor of cancer stemness simultaneously inhibits autophosphorylation of epidermal growth factor receptor and G9a-mediated stemness in lung cancer cells

Cancer stem cell survival is the leading factor for tumor recurrence after tumor-suppressive treatments. Therefore, specific and efficient inhibitors of cancer stemness must be discovered for reducing tumor recurrence. YM155 has been indicated to significantly reduce stemness-derived tumorsphere formation. However, the pharmaceutical mechanism of YM155 against cancer stemness is unclear. This study investigated the potential mechanism of YM155 against cancer stemness in lung cancer. Tumorspheres derived from epidermal growth factor receptor (EGFR)-mutant HCC827 and EGFR wild-type A549 cells expressing higher cancer stemness markers (CD133, Oct4, and Nanog) were used as cancer stemness models. We observed that EGFR autophosphorylation (Y1068) was higher in HCC827- and A549-derived tumorspheres than in parental cells; this autophosphorylation induced tumorsphere formation by activating G9a-mediated stemness. Notably, YM155 inhibited tumorsphere formation by blocking the autophosphorylation of EGFR and the EGFR-G9a-mediated stemness pathway. The chemical and genetic inhibition of EGFR and G9a revealed the significant role of the EGFR-G9a pathway in maintaining the cancer stemness property. In conclusion, this study not only revealed that EGFR could trigger tumorsphere formation by elevating G9a-mediated stemness but also demonstrated that YM155 could inhibit this formation by simultaneously blocking EGFR autophosphorylation and G9a activity, thus acting as a potent agent against lung cancer stemness.

Action of YM155 on clear cell renal cell carcinoma does not depend on survivin expression levels

The dioxonapthoimidazolium YM155 is a survivin suppressant which has been investigated as an anticancer agent in clinical trials. Here, we investigated its growth inhibitory properties on a panel of immortalized and patient derived renal cell carcinoma (RCC) cell lines which were either deficient in the tumour suppressor von Hippel-Lindau (VHL) protein or possessed a functional copy. Neither the VHL status nor the survivin expression levels of these cell lines influenced their susceptibility to growth inhibition by YM155. Of the various RCC lines, the papillary subtype was more resistant to YM155, suggesting that the therapeutic efficacy of YM155 may be restricted to clear cell subtypes. YM155 was equally potent in cells (RCC786.0) in which survivin expression had been stably silenced or overexpressed, implicating a limited reliance on survivin in the mode of action of YM155. A follow-up in-vitro high throughput RNA microarray identified possible targets of YM155 apart from survivin. Selected genes (ID1, FOXO1, CYLD) that were differentially expressed in YM155-sensitive RCC cells and relevant to RCC pathology were validated with real-time PCR and western immunoblotting analyses. Thus, there is corroboratory evidence that the growth inhibitory activity of YM155 in RCC cell lines is not exclusively mediated by its suppression of survivin. In view of the growing importance of combination therapy in oncology, we showed that a combination of YM155 and sorafenib at ½ x IC50 concentrations was synergistic on RCC786.0 cells. However, when tested intraperitoneally on a murine xenograft model derived from a nephrectomised patient with clear cell RCC, a combination of suboptimal doses of both drugs failed to arrest tumour progression. The absence of synergy in vivo highlighted the need to further optimize the dosing schedules of YM155 and sorafenib, as well as their routes of administration. It also implied that the expression of other oncogenic proteins which YM155 may target is either low or absent in this clear cell RCC.

Exploiting AR-Regulated Drug Transport to Induce Sensitivity to the Survivin Inhibitor YM155

Androgen receptor (AR) signaling is fundamental to prostate cancer and is the dominant therapeutic target in metastatic disease. However, stringent androgen deprivation therapy regimens decrease quality of life and have been largely unsuccessful in curtailing mortality. Recent clinical and preclinical studies have taken advantage of the dichotomous ability of AR signaling to elicit growth-suppressive and differentiating effects by administering hyperphysiologic levels of testosterone. In this study, high-throughput drug screening identified a potent synergy between high-androgen therapy and YM155, a transcriptional inhibitor of survivin (BIRC5). This interaction was mediated by the direct transcriptional upregulation of the YM155 transporter SLC35F2 by the AR. Androgen-mediated YM155-induced cell death was completely blocked by the overexpression of multidrug resistance transporter ABCB1. SLC35F2 expression was significantly correlated with intratumor androgen levels in four distinct patient-derived xenograft models, and with AR activity score in a large gene expression dataset of castration-resistant metastases. A subset of tumors had significantly elevated SLC35F2 expression and, therefore, may identify patients who are highly responsive to YM155 treatment.

IMPLICATIONS

The combination of androgen therapy with YM155 represents a novel drug synergy, and SLC35F2 may serve as a clinical biomarker of response to YM155.

Survivin, a molecular target for therapeutic interventions in squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common cancer worldwide. The treatment of locally advanced disease generally requires various combinations of radiotherapy, surgery, and systemic therapy. Despite aggressive multimodal treatment, most of the patients relapse. Identification of molecules that sustain cancer cell growth and survival has made molecular targeting a feasible therapeutic strategy. Survivin is a member of the Inhibitor of Apoptosis Protein (IAP) family, which is overexpressed in most of the malignancies including SCC and totally absent in most of the normal tissues. This feature makes survivin an ideal target for cancer therapy. It orchestrates several important mechanisms to support cancer cell survival including inhibition of apoptosis and regulation of cell division. Overexpression of survivin in tumors is also associated with poor prognosis, aggressive tumor behavior, resistance to therapy, and high tumor recurrence. Various strategies have been developed to target survivin expression in cancer cells, and their effects on apoptosis induction and tumor growth attenuation have been demonstrated. In this review, we discuss recent advances in therapeutic potential of survivin in cancer treatment.

Harnessing Solute Carrier Transporters for Precision Oncology

Solute Carrier (SLC) transporters are a large superfamily of transmembrane carriers involved in the regulated transport of metabolites, nutrients, ions and drugs across cellular membranes. A subset of these solute carriers play a significant role in the cellular uptake of many cancer therapeutics, ranging from chemotherapeutics such as antimetabolites, topoisomerase inhibitors, platinum-based drugs and taxanes to targeted therapies such as tyrosine kinase inhibitors. SLC transporters are co-expressed in groups and patterns across normal tissues, suggesting they may comprise a coordinated regulatory circuit serving to mediate normal tissue functions. In cancer however, there are dramatic changes in expression patterns of SLC transporters. This frequently serves to feed the increased metabolic demands of the tumor cell for amino acids, nucleotides and other metabolites, but also presents a therapeutic opportunity, as increased transporter expression may serve to increase intracellular concentrations of substrate drugs. In this review, we examine the regulation of drug transporters in cancer and how this impacts therapy response, and discuss novel approaches to targeting therapies to specific cancers via tumor-specific aberrations in transporter expression. We propose that among the oncogenic changes in SLC transporter expression there exist emergent vulnerabilities that can be exploited therapeutically, extending the application of precision medicine from tumor-specific drug targets to tumor-specific determinants of drug uptake.

From Proteomic Analysis to Potential Therapeutic Targets: Functional Profile of Two Lung Cancer Cell Lines, A549 and SW900, Widely Studied in Pre-Clinical Research

Lung cancer is a serious health problem and the leading cause of cancer death worldwide. The standard use of cell lines as in vitro pre-clinical models to study the molecular mechanisms that drive tumorigenesis and access drug sensitivity/effectiveness is of undisputable importance. Label-free mass spectrometry and bioinformatics were employed to study the proteomic profiles of two representative lung cancer cell lines and to unravel the specific biological processes. Adenocarcinoma A549 cells were enriched in proteins related to cellular respiration, ubiquitination, apoptosis and response to drug/hypoxia/oxidative stress. In turn, squamous carcinoma SW900 cells were enriched in proteins related to translation, apoptosis, response to inorganic/organic substances and cytoskeleton organization. Several proteins with differential expression were related to cancer transformation, tumor resistance, proliferation, migration, invasion and metastasis. Combined analysis of proteome and interactome data highlighted key proteins and suggested that adenocarcinoma might be more prone to PI3K/Akt/mTOR and topoisomerase IIα inhibitors, and squamous carcinoma to Ck2 inhibitors. Moreover, ILF3 overexpression in adenocarcinoma, and PCNA and NEDD8 in squamous carcinoma shows them as promising candidates for therapeutic purposes. This study highlights the functional proteomic differences of two main subtypes of lung cancer models and hints several targeted therapies that might assist in this type of cancer.

YM155, a survivin suppressant, triggers PARP-dependent cell death (parthanatos) and inhibits esophageal squamous-cell carcinoma xenografts in mice

Here we demonstrated that sepantronium bromide (YM155), a survivin suppressant, inhibited esophageal squamous-cell carcinoma (ESCC) growth in mice bearing human ESCC xenografts without affecting body weight. In cell culture, YM155 decreased survivin levels and caused PARP-1 activation, poly-ADP polymer formation, and AIF translocation from the cytosol to the nucleus. Genetic knockdown of PARP-1 or AIF abrogated YM155-induced parthanatos cell death. Furthermore, FOS, JUN and c-MYC gene transcription, which is stimulated by activated PARP-1, was increased following YM155 treatment. Our data demonstrate that YM155 did not trigger apoptosis, but induced parthanatos, a cell death dependent on PARP-1 hyper-activation, and support clinical development of YM155 in ESCC.

Targeting survivin as a potential new treatment for chondrosarcoma of bone

Chondrosarcomas are malignant cartilage-forming bone tumors, which are intrinsically resistant to chemo- and radiotherapy, leaving surgical removal as the only curative treatment option. Therefore, our aim was to identify genes involved in chondrosarcoma cell survival that could serve as a target for therapy. siRNA screening for 51 apoptosis-related genes in JJ012 chondrosarcoma cells identified BIRC5, encoding survivin, as essential for chondrosarcoma survival. Using immunohistochemistry, nuclear as well as cytoplasmic survivin expression was analyzed in 207 chondrosarcomas of different subtypes. Nuclear survivin has been implicated in cell-cycle regulation while cytoplasmic localization is important for its anti-apoptotic function. RT-PCR was performed to determine expression of the most common survivin isoforms. Sensitivity to YM155, a survivin inhibitor currently in phase I/II clinical trial for other tumors, was examined in 10 chondrosarcoma cell lines using viability assay, apoptosis assay and cell-cycle analysis. Survivin expression was found in all chondrosarcoma patient samples. Higher expression of nuclear and cytoplasmic survivin was observed with increasing histological grade in central chondrosarcomas. Inhibition of survivin using YM155 showed that especially TP53 mutant cell lines were sensitive, but no caspase 3/7 or PARP cleavage was observed. Rather, YM155 treatment resulted in a block in S phase in two out of three chondrosarcoma cell lines, indicating that survivin is more involved in cell-cycle regulation than in apoptosis. Thus, survivin is important for chondrosarcoma survival and chondrosarcoma patients might benefit from survivin inhibition using YM155, for which TP53 mutational status can serve as a predictive biomarker.

Novel interactions between the HTLV antisense proteins HBZ and APH-2 and the NFAR protein family: Implications for the HTLV lifecycles

The human T-cell leukaemia virus type 1 and type 2 (HTLV-1/HTLV-2) antisense proteins HBZ and APH-2 play key roles in the HTLV lifecycles and persistence in the host. Nuclear Factors Associated with double-stranded RNA (NFAR) proteins NF90/110 function in the lifecycles of several viruses and participate in host innate immunity against infection and oncogenesis. Using GST pulldown and co-immunoprecipitation assays we demonstrate specific novel interactions between HBZ/APH-2 and NF90/110 and characterised the protein domains involved. Moreover we show that NF90/110 significantly enhance Tax mediated LTR activation, an effect that was abolished by HBZ but enhanced by APH-2. Additionally we found that HBZ and APH-2 modulate the promoter activity of survivin and are capable of antagonising NF110-mediated survivin activation. Thus interactions between HTLV antisense proteins and the NFAR protein family have an overall positive impact on HTLV infection. Hence NFARs may represent potential therapeutic targets in HTLV infected cells.

Significance of survivin as a prognostic factor and a therapeutic target in endometrial cancer

INTRODUCTION

Survivin is an anti-apoptotic protein encoded by the baculoviral inhibitor of apoptosis repeat-containing (BIRC5) gene and is upregulated in 83% of endometrial cancers. We aimed to elucidate the prognostic importance of BIRC5 expression, and evaluate survivin as a therapeutic target for endometrial cancer, by knock-down of BIRC5 and using the survivin inhibitor-YM155.

METHODS

RNA sequencing data in 234 patients with endometrial carcinoma was obtained from The Cancer Genome Atlas database, and analyzed using Kaplan-Meier method, log-rank test and Cox proportional hazard model. Expressions of survivin in 16 endometrial cancer cell lines were analyzed by western blotting. Knocking down effect on survivin expression was evaluated using a small interfering RNA (siRNA). The anti-proliferative and pro-apoptotic effects of YM155 were assessed with cell viability, flow cytometry, and annexin V/propidium iodide assays.

RESULTS

High expression of BIRC5 was associated with poor progression free survival (P=0.006), and shown to be an independent prognostic factor (HR=1.97, 95% CI=1.29-4.5, P=0.045). Survivin was upregulated in 14 of 16 (87.5%) endometrial cancer cell lines, compared with endometrial immortalized cells. Apoptosis was induced by knockdown of BIRC5 in all 3 cell lines examined. YM155 showed increased population of sub-G1 cells (P<0.001) in all 16 cell lines, and IC50 values to YM155 were <50nm in 15 cell lines. YM155 dose-dependently and significantly increased the apoptotic cell population in all 16 cell lines (P<0.001).

CONCLUSIONS

Present study indicated that survivin expression is a significant prognostic factor and that survivin is a promising therapeutic target for endometrial cancer.

Antiproliferative, DNA intercalation and redox cycling activities of dioxonaphtho[2,3-d]imidazolium analogs of YM155: A structure-activity relationship study

The anticancer agent YM155 is widely investigated as a specific survivin suppressant. More recently, YM155 was found to induce DNA damage and this has raised doubts as to whether survivin is its primary target. In an effort to assess the contribution of DNA damage to the anticancer activity of YM155, several analogs were prepared and evaluated for antiproliferative activity on malignant cells, participation in DNA intercalation and free radical generation by redox cycling. The intact positively charged scaffold was found to be essential for antiproliferative activity and intercalation but was less critical for redox cycling where the minimal requirement was a pared down bicyclic quinone. Side chain requirements at the N(1) and N(3) positions of the scaffold were more alike for redox cycling and intercalation than antiproliferative activity, underscoring yet again, the limited structural overlaps for these activities. Furthermore, antiproliferative activities were poorly correlated to DNA intercalation and redox cycling. Potent antiproliferative activity (IC50 9-23 nM), exceeding that of YM155, was found for a minimally substituted methyl analog AB7. Like YM155 and other dioxonaphthoimidazoliums, AB7 was a modest DNA intercalator but with weak redox cycling activity. Thus, the capacity of this scaffold to inflict direct DNA damage leading to cell death may not be significant and YM155 should not be routinely classified as a DNA damaging agent.

Influence of survivin-targeted therapy on chemosensitivity in the treatment of acute myeloid leukemia

Overexpression of survivin is observed in various hematological malignancies, including acute myeloid leukemia (AML). Studies show that elevated expression of survivin correlates with a worse clinic outcome in AML patients. It remains unclear whether inhibition of survivin may alter the efficacy of chemotherapy against AML. Here, we evaluate the effects of specific knockdown of survivin on AML cells' sensitivity to chemotherapy, and investigate the therapeutic potential of the transcription inhibitor of survivin YM155 either alone or in combination with chemotherapeutic agents. We found Kasumi-1 and HL-60 cells had relatively higher expression levels of survivin among all AML cell lines tested. Specific knockdown of survivin in Kasumi-1 and HL-60 cells resulted in: inhibition of cell proliferation; cell cycle G2/M arrest; induction of DNA damage response and apoptosis. Downregulation of survivin enhanced etoposide- or doxorubicin-induced anti-proliferative/anti-survival activity in AML cells. The small molecule inhibitor YM155 reduced survivin in a dose- and time-dependent manner and trigged apoptosis in Kasumi-1 and HL-60 cells. The combinatorial effects of YM155 and chemotherapeutics were either synergetic or antagonistic, depending upon the drugs used for combination and the type of AML cells being treated. Collectively, our data demonstrate that survivin plays an important role in the maintenance and proliferation of AML cells. While specific knockdown of survivin enhances chemosensitivity, the combinations of YM155 and chemotherapeutic agents exhibit synergetic or antagonistic effects on AML cells. Our findings provide a rationale for further assessment of survivin-targeted therapy in the treatment of patients with AML.

MicroRNA regulation and therapeutic targeting of survivin in cancer

Survivin, the smallest member of IAP (inhibitor of apoptosis) family, is a dual functional protein acting as a critical apoptosis inhibitor and key cell cycle regulator. Survivin is usually expressed in embryonic tissues during development and undetectable in most terminally differentiated tissues. Numerous studies demonstrate that survivin is selectively upregulated in almost all types of human malignancies and its overexpression positively correlates with poor prognosis, tumor recurrence, and therapeutic resistance. This differential expression of survivin in tumors and normal tissues draws a great interest to develop survivin-targeted therapy for cancer treatment. Nonetheless, the molecular mechanisms controlling survivin expression in malignant tumor cells have not been fully understood. While aberrant activation of receptor tyrosine kinases (RTKs) and the downstream signaling, such as PI-3K/Akt, MEK/MAPK, mTOR, and STAT pathways, have frequently been shown to upregulate survivin, recent data suggest that a class of noncoding RNAs, microRNAs (miRNAs) also play an important role in survivin dysregulation in human cancers. Here, we focus on survivin expression-regulated by specific miRNAs binding to the 3'-UTR of survivin mRNA, and summarize the latest advances on survivin-targeted therapy in clinical trials and the therapeutic potential of survivin-targeting miRNAs in cancer.

Targeting survivin in cancer: novel drug development approaches

Survivin is a well-established target in experimental cancer therapy. The molecule is over-expressed in most human tumors, but hardly detectable in normal tissues. Multiple functions in different subcellular compartments have been assigned. It participates in the control of cell division, apoptosis, the cellular stress response, and also in the regulation of cell migration and metastasis. Survivin expression has been recognized as a biomarker: high expression indicates an unfavorable prognosis and resistance to chemotherapeutic agents and radiation treatment. Survivin is an unconventional drug target and several indirect approaches have been exploited to affect its function and the phenotype of survivin-expressing cells. Interference with the expression of the survivin gene, the utilization of its messenger RNA, the intracellular localization, the interaction with binding partners, the stability of the survivin protein, and the induction of survivin-specific immune responses have been taken into consideration. A direct strategy to inhibit survivin has been based on the identification of a specifically interacting peptide. This peptide can recognize survivin intracellularly and cause the degradation of the ligand–survivin complex. Technology is being developed that might allow the derivation of small molecular-weight, drug-like compounds that are functionally equivalent to the peptide ligand.

Ilf3 and NF90 functions in RNA biology

Double-stranded RNA-binding proteins (DRBPs) are known to regulate many processes of RNA metabolism due, among others, to the presence of double-stranded RNA (dsRNA)-binding motifs (dsRBMs). Among these DRBPs, Interleukin enhancer-binding factor 3 (Ilf3) and Nuclear Factor 90 (NF90) are two ubiquitous proteins generated by mutually exclusive and alternative splicings of the Ilf3 gene. They share common N-terminal and central sequences but display specific C-terminal regions. They present a large heterogeneity generated by several post-transcriptional and post-translational modifications involved in their subcellular localization and biological functions. While Ilf3 and NF90 were first identified as activators of gene expression, they are also implicated in cellular processes unrelated to RNA metabolism such as regulation of the cell cycle or of enzymatic activites. The implication of Ilf3 and NF90 in RNA biology will be discussed with a focus on eukaryote transcription and translation regulation, on viral replication and translation as well as on noncoding RNA field.

Survivin as a therapeutic target in Sonic hedgehog-driven medulloblastoma

Medulloblastoma (MB) is a highly malignant brain tumor that occurs primarily in children. Although surgery, radiation and high-dose chemotherapy have led to increased survival, many MB patients still die from their disease, and patients who survive suffer severe long-term side effects as a consequence of treatment. Thus, more effective and less toxic therapies for MB are critically important. Development of such therapies depends in part on identification of genes that are necessary for growth and survival of tumor cells. Survivin is an inhibitor of apoptosis protein that regulates cell cycle progression and resistance to apoptosis, is frequently expressed in human MB and when expressed at high levels predicts poor clinical outcome. Therefore, we hypothesized that Survivin may have a critical role in growth and survival of MB cells and that targeting it may enhance MB therapy. Here we show that Survivin is overexpressed in tumors from patched (Ptch) mutant mice, a model of Sonic hedgehog (SHH)-driven MB. Genetic deletion of survivin in Ptch mutant tumor cells significantly inhibits proliferation and causes cell cycle arrest. Treatment with small-molecule antagonists of Survivin impairs proliferation and survival of both murine and human MB cells. Finally, Survivin antagonists impede growth of MB cells in vivo. These studies highlight the importance of Survivin in SHH-driven MB, and suggest that it may represent a novel therapeutic target in patients with this disease.

AAG8 promotes carcinogenesis by activating STAT3

Dysregulation of signalling pathways by changes of gene expression contributes to hallmarks of cancer. The ubiquitously expressed chaperone protein AAG8 (aging-associated gene 8 protein, encoded by the SIGMAR1 gene) is often found to be overexpressed in various cancers. AAG8 is involved in ER (endoplasmic reticulum)-associated degradation and has been intensively elaborated in neuroscience. However, its rationale in carcinogenesis has rarely been noticed. In this study, we explored the intrinsic oncogenetic roles of AAG8 in cancer cells and found that AAG8 promoted carcinogenesis both in vitro and in vivo. We further characterized AAG8, for the first time to our knowledge, as a STAT3 activator and elucidated that it alternatively activated STAT3 in addition to IL6/JAK pathway. Based on these findings and a drug screening study, we demonstrated that combined inhibition of AAG8 and IL6/JAK signalling synergistically limits cancer cell growth. Taken together, our findings shed light on the fundamental evidences for identification of AAG8 as an oncoprotein and potential target for cancer prevention, as well as highlight the importance of ER proteins in contributing to JAK/STAT signaling and carcinogenesis.

The solute carrier SLC35F2 enables YM155-mediated DNA damage toxicity

Genotoxic chemotherapy is the most common cancer treatment strategy. However, its untargeted generic DNA-damaging nature and associated systemic cytotoxicity greatly limit its therapeutic applications. Here, we used a haploid genetic screen in human cells to discover an absolute dependency of the clinically evaluated anticancer compound YM155 on solute carrier family member 35 F2 (SLC35F2), an uncharacterized member of the solute carrier protein family that is highly expressed in a variety of human cancers. YM155 generated DNA damage through intercalation, which was contingent on the expression of SLC35F2 and its drug-importing activity. SLC35F2 expression and YM155 sensitivity correlated across a panel of cancer cell lines, and targeted genome editing verified SLC35F2 as the main determinant of YM155-mediated DNA damage toxicity in vitro and in vivo. These findings suggest a new route to targeted DNA damage by exploiting tumor and patient-specific import of YM155.

Survivin and YM155: how faithful is the liaison?

Survivin belongs to the family of apoptosis inhibitors (IAPs), which antagonizes the induction of cell death. Dysregulated expression of IAPs is frequently observed in cancers, and the high levels of survivin in tumors compared to normal adult tissues make it an attractive target for pharmacological interventions. The small imidazolium-based compound YM155 has recently been reported to block the expression of survivin via inhibition of the survivin promoter. Recent data, however, question that this is the sole and main effect of this drug, which is already being tested in ongoing clinical studies. Here, we critically review the current data on YM155 and other new experimental agents supposed to antagonize survivin. We summarize how cells from various tumor entities and with differential expression of the tumor suppressor p53 respond to this agent in vitro and as murine xenografts. Additionally, we recapitulate clinical trials conducted with YM155. Our article further considers the potency of YM155 in combination with other anti-cancer agents and epigenetic modulators. We also assess state-of-the-art data on the sometimes very promiscuous molecular mechanisms affected by YM155 in cancer cells.

Therapeutic potential of sepantronium bromide YM155 in gemcitabine-resistant human urothelial carcinoma cells

Survivin is overexpressed in transitional cell carcinoma (TCC), the most common type of bladder cancer. Previous reports demonstrated that knockdown of survivin by siRNA induced apoptosis of TCC cells. The present study evaluated the therapeutic effects of sepantronium bromide (YM155), a novel small molecule survivin inhibitor under clinical trials, on TCC cells in vitro. BFTC905, a grade III TCC cell line derived from a patient of blackfoot disease in Taiwan, was the most gemcitabine-resistant cell line when compared to BFTC909, TSGH8301 and T24 in cytotoxicity assay, resulting from upregulation of securin and bcl-2 after gemcitabine treatment. YM155 caused potent concentration‑dependent cytotoxicity in 4 TCC cell lines (IC50s ≤20 nM), but exhibited no cytotoxicity in survivin-null primary human urothelial cells. For BFTC905 cells, addition of gemcitabine and/or cisplatin, the standard TCC chemotherapy regimen, to YM155 did not exert additive cytotoxic effects. Molecular analyses indicated that YM155 inhibited the proliferation of BFTC905 cells by increasing p27kip1, suppressing Ki-67, and inducing quiescence. In addition, YM155 elicited apoptosis manifested with DNA fragmentation through suppressing the expression of survivin, securin and bcl-2. Furthermore, YM155 induced autophagy in BFTC905 cells as autophagic inhibitor, 3-methyladenine, attenuated YM155-induced LC3B-II levels and reversed the cytotoxicity of YM155. mTOR inhibitors sirolimus and everolimus did not increase YM155-induced expression of LC3B-II nor augment YM155-induced cytotoxicity. These results indicate that YM155 exerts its lethal effect on BFTC905 cells via apoptotic and autophagic death pathways and suggest that YM155 may be a potential drug for the therapy of gemcitabine-resistant bladder cancer.