Survivin as a prognostic/predictive marker and molecular target in cancer therapy

Targeting survivin for cancer therapy: Strategies, small molecule inhibitors and vaccine based therapeutics in development

Survivin is a member of the family of inhibitors of apoptosis proteins (IAPs). It is involved in the normal mitotic process and acts as an anti-apoptotic molecule. While terminally differentiated normal tissues lack survivin, several human malignancies have significant protein levels. Resistance to chemotherapy and radiation in tumor cells is associated with survivin expression. Decreased tumor development, apoptosis, and increased sensitivity to chemotherapy and radiation are all effects of downregulating survivin expression or activity. As a prospective cancer treatment, small molecules targeting the transcription and translation of survivin and molecules that can directly bind with the survivin are being explored both in pre-clinical and clinics. Pre-clinical investigations have found and demonstrated the effectiveness of several small-molecule survivin inhibitors. Unfortunately, these inhibitors have also been shown to have off-target effects, which could limit their clinical utility. In addition to small molecules, several survivin peptide vaccines are currently under development. These vaccines are designed to elicit a cytotoxic T-cell response against survivin, which could lead to the destruction of tumor cells expressing survivin. Some survivin-based vaccines are advancing through Phase II clinical studies. Overall, survivin is a promising cancer drug target. However, challenges still need to be addressed before the survivin targeted therapies can be widely used in the clinics.

Peptide-Based Vaccine against Breast Cancer: Recent Advances and Prospects

Breast cancer is considered the second-leading cancer after lung cancer and is the most prevalent cancer among women globally. Currently, cancer immunotherapy via vaccine has gained great attention due to specific and targeted immune cell activity that creates a potent immune response, thus providing long-lasting protection against the disease. Despite peptides being very susceptible to enzymatic degradation and poor immunogenicity, they can be easily customized with selected epitopes to induce a specific immune response and particulate with carriers to improve their delivery and thus overcome their weaknesses. With advances in nanotechnology, the peptide-based vaccine could incorporate other components, thereby modulating the immune system response against breast cancer. Considering that peptide-based vaccines seem to show remarkably promising outcomes against cancer, this review focuses on and provides a specific view of peptide-based vaccines used against breast cancer. Here, we discuss the benefits associated with a peptide-based vaccine, which can be a mainstay in the prevention and recurrence of breast cancer. Additionally, we also report the results of recent trials as well as plausible prospects for nanotechnology against breast cancer.

Dihydromyricetin suppresses tumor growth via downregulation of the EGFR/Akt/survivin signaling pathway

Deregulation of epidermal growth factor receptor (EGFR) signaling is frequently observed in non-small cell lung cancer (NSCLC). The present study aimed to determine the impact of dihydromyricetin (DHM) on NSCLC, a natural compound extracted from Ampelopsis grossedentata with various pharmacological activities. Results of the present study demonstrated that DHM may act as a promising antitumor agent for NSCLC therapy, inhibiting the growth of cancer cells in vitro and in vivo. Mechanistically, results of the present study demonstrated that exposure to DHM downregulated the activity of wild-type (WT) and mutant EGFRs (mutations, exon 19 deletion, and L858R/T790M mutation). Moreover, western blot analysis indicated that DHM induced cell apoptosis via suppression of the antiapoptotic protein, survivin. Results of the present study further demonstrated that depletion or activation of EGFR/Akt signaling may regulate survivin expression though modulating ubiquitination. Collectively, these results suggested that DHM may act as a potential EGFR inhibitor, and may provide a novel choice of treatment strategy for patients with NSCLC.

Canine mammary carcinoma: current therapeutic targets and future perspectives – a review

Canine mammary carcinoma (CMC) is the most common neoplasm in bitches, and it shares many biological similarities with breast cancer in humans. Drug resistance, high epigenetic mutations, and relapse rates are among the challenges which eventually urge the need for a veterinary oncologist to discover new therapeutic approaches that are more effective and safer. Therefore, in this review, we also cover the current therapeutic strategies from human medicine for the future perspectives of tumor immunotherapy in veterinary medicine. These strategies have great potential to be employed as therapeutic or prophylactic options due to their ability to modulate a specific and potent immune response against CMC. As we acquire a better understanding of canine tumor immunology, we can move towards a brighter prognosis. Additionally, we report on the recent successful studies in breast cancer that may benefit canines as well.

Study on differentially expressed genes between stage M and stage MS neuroblastoma

Objective

To search for the DEGs between stage MS NB and stage M NB and speculate the possible mechanism of spontaneous regression of stage MS NB.

Materials and methods

The NB datasets GSE49710 and GSE45547 in the GEO database were selected to screen the DEGs between children with NB stage MS vs. stage M, < 18 months. GO enrichment and KEGG pathway analysis of DEGs was performed using DAVID. The intersecting genes among DEGs and RCD-related genes were selected, and their survival roles and functions were assessed. We then used the collected clinical samples to validate the expression of these genes at the protein level using IHC methods and further analysis to explore their role.

Results

BIRC5, SLCO4A1, POPDC3, and HK2 were found to be downregulated in stage MS NB and related to apoptosis. BIRC5 and HK2 also participate in autophagy. The TF gene is upregulated in stage MS NB and related to ferroptosis. The above five genes are closely related to the survival of children with NB. And the expression levels of all five genes at the protein level were verified by IHC to be consistent with the results of the preliminary screening described above.

Conclusion

BIRC5, SLCO4A1, POPDC3, HK2 and TF are expected to become new important indicators to predict the prognosis of NB and can be used as the basis for further explored the benign prognosis and spontaneous regression mechanism of stage MS NB.

Hypoxia induces docetaxel resistance in triple-negative breast cancer via the HIF-1α/miR-494/Survivin signaling pathway

Cytotoxic chemotherapy is the major strategy to prevent and reduce triple-negative breast cancer (TNBC) progression and metastasis. Hypoxia increases chemoresistance and is associated with a poor prognosis for patients with cancer. Based on accumulating evidence, microRNAs (miRNAs) play an important role in acquired drug resistance. However, the role of miRNAs in hypoxia-induced TNBC drug resistance remains to be clarified. Here, we found that hypoxia induced TNBC docetaxel resistance by decreasing the miR-494 level. Modulating miR-494 expression altered the sensitivity of TNBC cells to DTX under hypoxic conditions. Furthermore, we identified Survivin as a direct miR-494 target. Hypoxia upregulated survivin expression. In a clinical study, the HIF-1α/miR-494/Survivin signaling pathway was also active in primary human TNBC, and miR-494 expression negatively correlated with HIF-1α and survivin expression. Finally, in a xenograft model, both miR-494 overexpression and the HIF-1α inhibitor PX-478 increased the sensitivity of TNBC to DTX by suppressing the HIF-1α/miR-494/Survivin signaling pathway in vivo. In conclusion, treatments targeting the HIF-1α/miR-494/Survivin signaling pathway potentially reverse hypoxia-induced drug resistance in TNBC.

Upregulation of Nox4 induces a pro-survival Nrf2 response in cancer-associated fibroblasts that promotes tumorigenesis and metastasis, in part via Birc5 induction

BACKGROUND

A pro-oxidant enzyme, NADPH oxidase 4 (Nox4) has been reported to be a critical downstream effector of TGFβ-induced myofibroblast transformation during fibrosis. While there are a small number of studies suggesting an oncogenic role of Nox4 derived from activated fibroblasts, direct evidence linking this pro-oxidant to the tumor-supporting CAF phenotype and the mechanisms involved are lacking, particularly in breast cancer.

METHODS

We targeted Nox4 in breast patient-derived CAFs via siRNA-mediated knockdown or administration of a pharmaceutical inhibitor (GKT137831). We also determine primary tumor growth and metastasis of implanted tumor cells using a stable Nox4-/- syngeneic mouse model. Autophagic flux of CAFs was assessed using a tandem fluorescent-tagged ptfl-LC3 plasmid via confocal microscopy analysis and determination of the expression level of autophagy markers (beclin-1 and LC3B). Nox4 overexpressing CAFs depend on the Nrf2 (nuclear factor-erythroid factor 2-related factor 2) pathway for survival. We then determined the dependency of Nox4-overexpressing CAFs on the Nrf2-mediated adaptive stress response pathway for survival. Furthermore, we investigated the involvement of Birc5 on CAF phenotype (viability and collagen contraction activity) as well as the expression level of CAF markers, FAP and αSMA.

CONCLUSIONS

We found that deletion of stroma Nox4 and pharmaceutically targeting its activity with GKT137831 significantly inhibited orthotopic tumor growth and metastasis of implanted E0771 and 4T1 murine mammary carcinoma cell lines in mice. More importantly, we found a significant upregulation of Nox4 expression in CAFs isolated from human breast tumors versus normal mammary fibroblasts (RMFs). Our in situ RNA hybridization analysis for Nox4 transcription on a human breast tumor microarray further support a role of this pro-oxidant in the stroma of breast carcinomas. In addition, we found that Nox4 promotes autophagy in CAFs. Moreover, we found that Nox4 promoted survival of CAFs via activation of Nrf2, a master regulator of oxidative stress response. We have further shown Birc5 is involved as a downstream modulator of Nrf2-mediated pro-survival phenotype. Together these studies indicate a role of redox signaling via the Nox4-Nrf2 pathway in tumorigenesis and metastasis of breast cancer cells by promoting autophagy and survival of CAFs.

Synthetic Antibodies Detect Distinct Cellular States of Chromosome Passenger Complex Proteins

High performance affinity reagents are essential tools to enable biologists to profile the cellular location and composition of macromolecular complexes undergoing dynamic reorganization. To support further development of such tools, we have assembled a high-throughput phage display pipeline to generate Fab-based affinity reagents that target different dynamic forms of a large macromolecular complex, using the Chromosomal Passenger Complex (CPC), as an example. The CPC is critical for the maintenance of chromosomal and cytoskeleton processes during cell division. The complex contains 4 protein components: Aurora B kinase, survivin, borealin and INCENP. The CPC acts as a node to dynamically organize other partnering subcomplexes to build multiple functional structures during mitotic progression. Using phage display mutagenesis, a cohort of synthetic antibodies (sABs) were generated against different domains of survivin, borealin and INCENP. Immunofluorescence established that a set of these sABs can discriminate between the form of the CPC complex in the midbody versus the spindle. Others localize to targets, which appear to be less organized, in the nucleus or cytoplasm. This differentiation suggests that different CPC epitopes have dynamic accessibility depending upon the mitotic state of the cell. An Immunoprecipitation/Mass Spectrometry analysis was performed using sABs that bound specifically to the CPC in either the midbody or MT spindle macromolecular assemblies. Thus, sABs can be exploited as high performance reagents to profile the accessibility of different components of the CPC within macromolecular assemblies during different stages of mitosis suggesting this high throughput approach will be applicable to other complex macromolecular systems.

Value of c-MET and Associated Signaling Elements for Predicting Outcomes and Targeted Therapy in Penile Cancer

Whereas the lack of biomarkers in penile cancer (PeCa) impedes the development of efficacious treatment protocols, preliminary evidence suggests that c-MET and associated signaling elements may be dysregulated in this disorder. In the following study, we investigated whether c-MET and associated key molecular elements may have prognostic and therapeutic utility in PeCa. Formalin-fixed, paraffin-embedded tumor tissue from therapy-naïve patients with invasive PeCa was used for tissue microarray (TMA) analysis. Immunohistochemical staining was performed to determine the expression of the proteins c-MET, PPARg, β-catenin, snail, survivin, and n-MYC. In total, 94 PeCa patients with available tumor tissue were included. The median age was 64.9 years. High-grade tumors were present in 23.4%, and high-risk HPV was detected in 25.5%. The median follow-up was 32.5 months. High expression of snail was associated with HPV-positive tumors. Expression of β-catenin was inversely associated with grading. In both univariate COX regression analysis and the log-rank test, an increased expression of PPARg and c-MET was predictive of inferior disease-specific survival (DSS). Moreover, in multivariate analysis, a higher expression of c-MET was independently associated with worse DSS. Blocking c-MET with cabozantinib and tivantinib induced a significant decrease in viability in the primary PeCa cell line UKF-PeC3 isolated from the tumor tissue as well as in cisplatin- and osimertinib-resistant sublines. Strikingly, a higher sensitivity to tivantinib could be detected in the latter, pointing to the promising option of utilizing this agent in the second-line treatment setting.

Hypoxia Activates Notch4 via ERK/JNK/P38 MAPK Signaling Pathways to Promote Lung Adenocarcinoma Progression and Metastasis

Hypoxia contributes to the progression and metastasis of lung adenocarcinoma (LUAD). However, the specific underlying molecular mechanisms have not been fully elucidated. Here we report that Notch4 is upregulated in lung tissue from lung cancer patients. Functionally, Hypoxia activates the expressions of Delta-like 4 and Notch4, resulting in the excessive proliferation and migration of LUAD cells as well as apoptotic resistance. Notch4 silencing reduced ERK, JNK, and P38 activation. Meanwhile, Notch4 overexpression enhanced ERK, JNK, and P38 activation in LUAD cells. Furthermore, Notch4 exerted pro-proliferation, anti-apoptosis and pro-migration effects on LUAD cells that were partly reversed by the inhibitors of ERK, JNK, and p38. The binding interaction between Notch4 and ERK/JNK/P38 were confirmed by the co-immunoprecipitation assay. In vivo study revealed that Notch4 played a key role in the growth and metastasis of LUAD using two xenograft models. This study demonstrates that hypoxia activates Notch4-ERK/JNK/P38 MAPK signaling pathways to promote LUAD cell progression and metastasis.

MRI detection of the malignant transformation of stem cells through reporter gene expression driven by a tumor-specific promoter

Background

Existing evidence has shown that mesenchymal stem cells (MSCs) can undergo malignant transformation, which is a serious limitation of MSC-based therapies. Therefore, it is necessary to monitor malignant transformation of MSCs via a noninvasive imaging method. Although reporter gene-based magnetic resonance imaging (MRI) has been successfully applied to longitudinally monitor MSCs, this technique cannot distinguish the cells before and after malignant transformation. Herein, we investigated the feasibility of using a tumor-specific promoter to drive reporter gene expression for MRI detection of the malignant transformation of MSCs.

Methods

The reporter gene ferritin heavy chain (FTH1) was modified by adding a promoter from the tumor-specific gene progression elevated gene-3 (PEG3) and transduced into MSCs to obtain MSCs-PEG3-FTH1. Cells were induced to undergo malignant transformation via indirect coculture with C6 glioma cells, and these transformed cells were named MTMSCs-PEG3-FTH1. Western blot analysis of FTH1 expression, Prussian blue staining and transmission electron microscopy (TEM) to detect intracellular iron, and MRI to detect signal changes were performed before and after malignant transformation. Then, the cells before and after malignant transformation were inoculated subcutaneously into nude mice, and MRI was performed to observe the signal changes in the xenografts.

Results

After induction of malignant transformation, MTMSCs demonstrated tumor-like features in morphology, proliferation, migration, and invasion. FTH1 expression was significantly increased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. Prussian blue staining and TEM showed a large amount of iron particles in MTMSCs-PEG3-FTH1 but a minimal amount in MSCs-PEG3-FTH1. MRI demonstrated that the T2 value was significantly decreased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. In vivo, mass formation was observed in the MTMSCs-PEG3-FTH1 group but not the MSCs-PEG3-FTH1 group. T2-weighted MRI showed a significant signal decrease, which was correlated with iron accumulation in the tissue mass.

Conclusions

We developed a novel MRI model based on FTH1 reporter gene expression driven by the tumor-specific PEG3 promoter. This approach could be applied to sensitively detect the occurrence of MSC malignant transformation.

Tumor Suppressor Protein p53 and Inhibitor of Apoptosis Proteins in Colorectal Cancer-A Promising Signaling Network for Therapeutic Interventions

Simple Summary

Tumor suppressor 53 (p53) is a multifunctional protein that regulates cell cycle, DNA repair, apoptosis and metabolic pathways. In colorectal cancer (CRC), mutations of the gene occur in 60% of patients and are associated with a more aggressive tumor phenotype and resistance to anti-cancer therapy. In addition, inhibitor of apoptosis (IAP) proteins are distinguished biomarkers overexpressed in CRC that impact on a diverse set of signaling pathways associated with the regulation of apoptosis/autophagy, cell migration, cell cycle and DNA damage response. As these mechanisms are further firmly controlled by p53, a transcriptional and post-translational regulation of IAPs by p53 is expected to occur in cancer cells. Here, we aim to review the molecular regulatory mechanisms between IAPs and p53 and discuss the therapeutic potential of targeting their interrelationship by multimodal treatment options.

Abstract

Despite recent advances in the treatment of colorectal cancer (CRC), patient’s individual response and clinical follow-up vary considerably with tumor intrinsic factors to contribute to an enhanced malignancy and therapy resistance. Among these markers, upregulation of members of the inhibitor of apoptosis protein (IAP) family effects on tumorigenesis and radiation- and chemo-resistance by multiple pathways, covering a hampered induction of apoptosis/autophagy, regulation of cell cycle progression and DNA damage response. These mechanisms are tightly controlled by the tumor suppressor p53 and thus transcriptional and post-translational regulation of IAPs by p53 is expected to occur in malignant cells. By this, cellular IAP1/2, X-linked IAP, Survivin, BRUCE and LIVIN expression/activity, as well as their intracellular localization is controlled by p53 in a direct or indirect manner via modulating a multitude of mechanisms. These cover, among others, transcriptional repression and the signal transducer and activator of transcription (STAT)3 pathway. In addition, p53 mutations contribute to deregulated IAP expression and resistance to therapy. This review aims at highlighting the mechanistic and clinical importance of IAP regulation by p53 in CRC and describing potential therapeutic strategies based on this interrelationship.

A Spatial and Functional Interaction of a Heterotetramer Survivin-DNA-PKcs Complex in DNA Damage Response

Substantial evidence has shown that overexpression of the inhibitor of apoptosis protein (IAP) survivin in human tumors correlates significantly with treatment resistance and poor patient prognosis. Survivin serves as a radiation resistance factor that impacts the DNA damage response by interacting with DNA-dependent protein kinase (DNA-PKcs). However, the complexity, molecular determinants, and functional consequences of this interrelationship remain largely unknown. By applying coimmunoprecipitation and flow cytometry-based Förster resonance energy transfer assays, we demonstrated a direct involvement of the survivin baculovirus IAP repeat domain in the regulation of radiation survival and DNA repair. This survivin-mediated activity required an interaction of residues S20 and W67 with the phosphoinositide 3-kinase (PI3K) domain of DNA-PKcs. In silico molecular docking and dynamics simulation analyses, in vitro kinase assays, and large-scale mass spectrometry suggested a heterotetrameric survivin-DNA-PKcs complex that results in a conformational change within the DNA-PKcs PI3K domain. Overexpression of survivin resulted in enhanced PI3K enzymatic activity and detection of differentially abundant phosphopeptides and proteins implicated in the DNA damage response. The survivin-DNA-PKcs interaction altered the S/T-hydrophobic motif substrate specificity of DNA-PKcs with a predominant usage of S/T-P phosphorylation sites and an increase of DNA-PKcs substrates including Foxo3. These data demonstrate that survivin differentially regulates DNA-PKcs-dependent radiation survival and DNA double-strand break repair via formation of a survivin-DNA-PKcs heterotetrameric complex. SIGNIFICANCE: These findings provide insight into survivin-mediated regulation of DNA-PKcs kinase and broaden our knowledge of the impact of survivin in modulating the cellular radiation response.See related commentary by Iliakis, p. 2270 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/9/2304/F1.large.jpg.

Unraveling novel survivin mRNA transcripts in cancer cells using an in-house developed targeted high-throughput sequencing approach

The human baculoviral IAP repeat containing 5 (BIRC5), also known as survivin, is a conserved member of the inhibitor of apoptosis protein (IAPs) family, which is normally expressed during embryonic and fetal development. Although the expression levels of survivin are low in terminally differentiated cells and/or tissues, they can be found notably increased in certain pathological conditions including malignant tumors. Conventional cloning and sequencing techniques have already confirmed that alternative splicing events of the survivin pre-mRNA result in five distinct alternative transcript variants. In the present study, however, we implemented an innovative, in-house developed, targeted DNA-seq assay to identify novel survivin alternative transcript variants with increased depth and coverage that high-throughput sequencing approaches offer. Bioinformatics analysis of the derived NGS datasets unveiled several novel splice junctions between annotated exons of survivin gene as well as the existence of a novel exon of 117 nt, spanning between the annotated exons 3 and 3B. Validation of the NGS findings with PCR-based assays, using variant-specific primers, led to the identification of fourteen novel survivin alternative splice variants (BIRC5 v.4 - v.17), which demonstrate wide expression profiles in a broad established panel of human cell lines. Although the presented novel findings provide a crystal-clear overview of the survivin mRNAs that are actually generated from the pre-mRNA, future studies should focus on the impending necessity of characterizing the biological function of all novel alternative transcript variants as well as the putative protein isoforms. Such studies will further contribute to our understanding of how the balance between survivin isoforms regulate malignant cell proliferation and apoptosis, providing novel diagnostic, prognostic and predictive biomarkers as well as therapeutic targets.

Testing of the Survivin Suppressant YM155 in a Large Panel of Drug-Resistant Neuroblastoma Cell Lines

The survivin suppressant YM155 is a drug candidate for neuroblastoma. Here, we tested YM155 in 101 neuroblastoma cell lines (19 parental cell lines, 82 drug-adapted sublines). Seventy seven (77) cell lines displayed YM155 IC₅₀s in the range of clinical YM155 concentrations. ABCB1 was an important determinant of YM155 resistance. The activity of the ABCB1 inhibitor zosuquidar ranged from being similar to that of the structurally different ABCB1 inhibitor verapamil to being 65-fold higher. ABCB1 sequence variations may be responsible for this, suggesting that the design of variant-specific ABCB1 inhibitors may be possible. Further, we showed that ABCC1 confers YM155 resistance. Previously, p53 depletion had resulted in decreased YM155 sensitivity. However, TP53-mutant cells were not generally less sensitive to YM155 than TP53 wild-type cells in this study. Finally, YM155 cross-resistance profiles differed between cells adapted to drugs as similar as cisplatin and carboplatin. In conclusion, the large cell line panel was necessary to reveal an unanticipated complexity of the YM155 response in neuroblastoma cell lines with acquired drug resistance. Novel findings include that ABCC1 mediates YM155 resistance and that YM155 cross-resistance profiles differ between cell lines adapted to drugs as similar as cisplatin and carboplatin.

Identification of potential key genes for HER-2 positive breast cancer based on bioinformatics analysis

BACKGROUNDS

HER-2 positive breast cancer is a subtype of breast cancer with poor clinical outcome. The aim of this study was to identify differentially expressed genes (DEGs) for HER-2 positive breast cancer and elucidate the potential interactions among them.

MATERIAL AND METHODS

Three gene expression profiles (GSE29431, GSE45827, and GSE65194) were derived from the Gene Expression Omnibus (GEO) database. GEO2R tool was applied to obtain DEGs between HER-2 positive breast cancer and normal breast tissues. Gene ontology (GO) annotation analysis and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis was performed by the Database for Annotation, Visualization and Integrated Discovery (David) online tool. Protein-protein interaction (PPI) network, hub gene identification and module analysis was conducted by Cytoscape software. Online Kaplan-Meier plotter survival analysis tool was also used to investigate the prognostic values of hub genes in HER-2 positive breast cancer patients.

RESULTS

A total of 54 upregulated DEGs and 269 downregulated DEGs were identified. Among them, 10 hub genes including CCNB1, RAC1, TOP2A, KIF20A, RRM2, ASPM, NUSAP1, BIRC5, BUB1B, and CEP55 demonstrated by connectivity degree in the PPI network were screened out. In Kaplan-Meier plotter survival analysis, the overexpression of RAC1 and RRM2 were shown to be associated with an unfavorable prognosis in HER-2 positive breast cancer patients.

CONCLUSIONS

This present study identified a number of potential target genes and pathways which might impact the oncogenesis and progression of HER-2 positive breast cancer. These findings could provide new insights into the detection of novel diagnostic and therapeutic biomarkers for this disease.

The Natural-Based Antitumor Compound T21 Decreases Survivin Levels through Potent STAT3 Inhibition in Lung Cancer Models

Lung cancer is the leading cause of cancer-related deaths worldwide; hence novel treatments for this malignancy are eagerly needed. Since natural-based compounds represent a rich source of novel chemical entities in drug discovery, we have focused our attention on tambjamines, natural compounds isolated from marine invertebrates that have shown diverse pharmacological activities. Based on these structures, we have recently identified the novel indole-based tambjamine analog 21 (T21) as a promising antitumor agent, which modulates the expression of apoptotic proteins such as survivin. This antiapoptotic protein plays an important role in carcinogenesis and chemoresistance. In this work, we have elucidated the molecular mechanism by which the anticancer compound T21 exerts survivin inhibition and have validated this protein as a therapeutic target in different lung cancer models. T21 was able to reduce survivin protein levels in vitro by repressing its gene expression through the blockade of Janus kinase/Signal Transducer and Activator of Transcription-3 (JAK/STAT3)/survivin signaling pathway. Interestingly, this occurred even when the pathway was overstimulated with its ligand interleukin 6 (IL-6), which is frequently overexpressed in lung cancer patients who show poor clinical outcomes. Altogether, these results show T21 as a potent anticancer compound that effectively decreases survivin levels through STAT3 inhibition in lung cancer, appearing as a promising therapeutic drug for cancer treatment.

Growth arrest and apoptosis induced by kinesin Eg5 inhibitor K858 and by its 1,3,4-thiadiazoline analogue in tumor cells

Tumors are complex and heterogeneous but, despite this, they share the ability to proliferate continuously, irrespective of the presence of growth signals, leading to a higher fraction of actively growing and dividing cells compared with normal tissues. For this reason, the cytotoxic antimitotic treatments remain an important clinical tool for tumors. Among these drugs, antitubulin compounds constitute one of the most effective anticancer chemotherapies; however, they cause dose-limiting side effects. Therefore, it is still necessary to develop compounds with new targets and new mechanisms of action to reduce side effects or chemoresistance. Mitosis-specific kinesin Eg5 can represent an attractive target for discovering such new anticancer agents because its role is fundamental in mitotic progression. Therefore, we analyzed the effects induced by an inhibitor of kinesin Eg5, K858, and by its 1,3,4-thiadiazoline analogue on human melanoma and prostate cancer cell lines. We found that both compounds have an antiproliferative effect, induce apoptosis, and can determine a downmodulation of survivin.

RNA helicase p68 deploys β-catenin in regulating RelA/p65 gene expression: implications in colon cancer

BACKGROUND

RelA/p65 a crucial member of NF-κB signaling pathway plays diverse role in mediating oncogenesis. Limited knowledge prevails on the mechanistic insights of RelA gene regulation. RNA helicase p68 apart from being a vital player of RNA metabolism acts as a transcriptional coactivator of several oncogenic transcription factors including β-catenin and is highly implicated in cancer progression. In this study, we aim to discern the molecular mechanism of how an RNA helicase, p68 deploys a major oncogenic signaling pathway, Wnt/ β-catenin to regulate the expression of RelA, an indispensable component of NF-κB signaling pathway towards driving colon carcinogenesis.

METHODS

Immunoblotting and quantitative RT-PCR was performed for determining the protein and mRNA expressions of the concerned genes respectively. Luciferase assay was employed for studying the promoter activity of RelA. Chromatin immunoprecipitation was used to evaluate the occupancy of transcription factors on the RelA promoter. Immunohistochemical analysis was conducted using FFPE sections derived from normal human colon and colon cancer patient samples. Finally, a syngeneic colorectal allograft mouse model was used to assess physiological significance of the in vitro findings.

RESULTS

p68, β-catenin and RelA proteins were found to bear strong positive correlation in normal and colon carcinoma patient samples. Both p68 and β-catenin increased RelA mRNA and protein expression. p68, β-catenin and Wnt3a elevated RelA promoter activity. Conversely, p68 and β-catenin knockdown diminished RelA promoter activity and led to reduced RelA mRNA and protein expression. p68 was perceived to occupy RelA promoter with β-catenin at the TCF4/LEF (TBE) sites thereby potentiating RelA transcription. p68 and β-catenin alliance positively modulated the expression of signature NF-κB target genes. Enhanced NF-κB target gene expression by p68 was corroborated by findings in clinical samples. Tumors generated in mice colorectal allograft model, stably expressing p68 further reinforced our in vitro findings.

CONCLUSIONS

We report for the first time a novel mechanism of alliance between p68 and β-catenin in regulating the expression of RelA and stimulating the NF-κB signaling axis towards driving colon carcinogenesis. This study unravels novel modes of p68-mediated colon carcinogenesis, marking it a potential target for therapy.

Comparison of Radiosensitization by HDAC Inhibitors CUDC-101 and SAHA in Pancreatic Cancer Cells

Pancreatic cancer has a poor prognosis. New treatment options are urgently required to improve patient outcomes. One promising new class of anticancer drugs are synthetic histone deacetylase inhibitors (HDACi) which modulate chromatin structure and gene expression by blocking histone deacetylation. In this study, we aimed at comparing the in vitro capacities of the HDACi SAHA and CUDC-101 to increase radiosensitivity of human pancreatic tumor cell lines. Therefore, three pancreatic cancer cell lines (Su.86.86, MIA Paca-2, T3M-4) were treated with SAHA (1.5–5 µM) or CUDC-101 (0.25–3 µM) and after 24 h irradiated. Cell proliferation, clonogenic survival and apoptosis was determined. Additionally, cell lysates were investigated for the expression of apoptosis-related proteins. CUDC-101 and SAHA increased the radiation sensitivity of pancreatic tumor cell lines in a dose-dependent manner. This was evidenced by cell proliferation and clonogenic survival. Furthermore, enhanced radiation sensitivity after CUDC-101 or SAHA treatment was confirmed for Su.86.86 and T3M-4 cells in a 3-D microtissue approach. Increased amounts of subG1 cells and diminished full length PARP-1 suggest increased radiation-induced apoptosis after SAHA or CUDC-101 treatment. The comparison of both inhibitors in these assays manifested CUDC-101 as more potent radiosensitizer than SAHA. In line, western blot quantification of the apoptosis-inhibitory proteins XIAP and survivin showed a stronger down-regulation in response to CUDC-101 treatment than after SAHA application. These proteins may contribute to the synergy between HDAC inhibition and radiation response. In conclusion, these preclinical results suggest that treatment with the HDAC inhibitors CUDC-101 or SAHA can enhance radiation-induced cytotoxicity in human pancreatic cells. However, comparison of both inhibitors identified the multi target inhibitor CUDC-101 as more potent radiosensitizer than the HDAC inhibitor SAHA.

Toward early cancer detection: Focus on biosensing systems and biosensors for an anti-apoptotic protein survivin and survivin mRNA

The development of biosensors for cancer biomarkers has recently been expanding rapidly, offering promising biomedical applications of these sensors as highly sensitive, selective, and inexpensive bioanalytical tools that can provide alternative methodology to that afforded by the advanced hyphenated-instrumental techniques. In this review, we focus particularly on the detection of a member of the inhibitor of apoptosis proteins (IAP) family, protein survivin (Sur), a ubiquitous re-organizer of the cell life cycle with the ability to inhibit the apoptosis and induce an enhanced proliferation leading to the unimpeded cancer growth and metastasis. Herein, we critically evaluate the progress in the development of novel biosensing systems and biosensors for the detection of two survivin (Sur) biomarkers: the Sur protein and its messenger RNA (Sur mRNA), including immunosensors, electrochemical piezo- and impedance-sensors, electrochemi-luminescence biosensors, genosensors based on oligonucleotide molecular beacons (MBs) with fluorescent or electrochemical transduction, as well as the microfluidic and related analytical platforms based on solution chemistry. The in-situ applications of survivin biomarkers' detection technologies to equip nanocarriers of the controlled drug delivery systems with MB-based fluorescence imaging capability, apoptosis control, and mitigation of the acquired drug resistance are also presented and critically evaluated. Finally, we turn the attention to the application of biosensors for the analysis of Sur biomarkers in exosomes and circulating tumor cells for a non-invasive liquid biopsy. The prospect of a widespread screening for early cancers, based on inexpensive point-of-care testing using biosensors and multiplex biosensor arrays, as a means of reducing the high cancer fatality rate, is discussed.

Overexpression of survivin in pediatric Hodgkin lymphoma tumor cells: Characterization of protein expression and splice-variants transcription profile

Survivin is abundantly expressed during fetal development but absent in most differentiated adult tissues; an exception being components of the immune system, such as B and T lymphocytes. Beyond acting as a master regulator of the cell cycle, survivin acts as an inhibitor of apoptosis and is overexpressed in almost all carcinoma types; however, its expression in lymphomas is lesser-explored. Survivin's role in carcinogenesis was subjected to its sub-cellular localization and splice transcripts expression, namely wild-type survivin, survivin-∆Ex3 and survivin-2B. To assess survivin's expression and sub-cellular localization in Epstein Barr virus positive and negative biopsies from treatment naïve pediatric patients with Hodgkin lymphoma (HL), samples were stained for survivin protein by immunofluorescence. The proportion of survivin+ cells was calculated, survivin sub-cellular localization assessed and its fluorescence intensity quantified. Transcription profile of survivin mRNA variants was studied by RT-qPCR. Survivin was overexpressed in the nucleus of tumor cells, and also in a greater proportion of tumor cells, in comparison with the non-tumoral infiltrating cells. Although a higher expression of survivin was observed in advanced clinical stages, no correlation was found between the expression level of survivin and a proliferation marker, or event-free survival. Instead, survivin was related to apoptosis inhibition in tumor cells. Additionally, survivin's transcriptional variants displayed similar expression levels. Present results suggest that although survivin is overexpressed in Hodgkin's tumor cells, it may not play a central role in the progression of classic HL, or act as a suitable progression biomarker, as suggested for most carcinomas.

High Therapeutic Efficacy of a New Survivin LSP-Cancer Vaccine Containing CD4+ and CD8+ T-Cell Epitopes

The efficacy of an antitumoral vaccine relies both on the choice of the antigen targeted and on its design. The tumor antigen survivin is an attractive target to develop therapeutic cancer vaccines because of its restricted over-expression and vital functions in most human tumors. Accordingly, several clinical trials targeting survivin in various cancer indications have been conducted. Most of them relied on short peptide-based vaccines and showed promising, but limited clinical results. In this study, we investigated the immunogenicity and therapeutic efficacy of a new long synthetic peptide (LSP)-based cancer vaccine targeting the tumor antigen survivin (SVX). This SVX vaccine is composed of three long synthetic peptides containing several CD4⁺ and CD8⁺ T-cell epitopes, which bind to various HLA class II and class I molecules. Studies in healthy individuals showed CD4⁺ and CD8⁺ T-cell immunogenicity of SVX peptides in human, irrespective of the individual's HLA types. Importantly, high frequencies of spontaneous T-cell precursors specific to SVX peptides were also detected in the blood of various cancer patients, demonstrating the absence of tolerance against these peptides. We then demonstrated SVX vaccine's high therapeutic efficacy against four different established murine tumor models, associated with its capacity to generate both specific cytotoxic CD8⁺ and multifunctional Th1 CD4⁺ T-cell responses. When tumors were eradicated, generated memory T-cell responses protected against rechallenge allowing long-term protection against relapses. Treatment with SVX vaccine was also found to reshape the tumor microenvironment by increasing the tumor infiltration of both CD4⁺ and CD8⁺ T cells but not Treg cells therefore tipping the balance toward a highly efficient immune response. These results highlight that this LSP-based SVX vaccine appears as a promising cancer vaccine and warrants its further clinical development.

Therapeutic strategies involving survivin inhibition in cancer

Survivin is a small protein that belongs to the inhibitor of apoptosis protein family. It is abundantly expressed in tumors compared with adult differentiated tissues, being associated with poor prognosis in many human neoplasms. This apoptotic inhibitor has a relevant role in both the promotion of cancer cell survival and in the inhibition of cell death. Consequently, aberrant survivin expression stimulates tumor progression and confers resistance to several therapeutic strategies in a variety of tumors. In fact, efficient survivin downregulation or inhibition results in spontaneous apoptosis or sensitization to chemotherapy and radiotherapy. Therefore, all these features make survivin an attractive therapeutic target to treat cancer. Currently, there are several survivin inhibitors under clinical evaluation, although more specific and efficient survivin inhibitors are being developed. Moreover, novel combination regimens targeting survivin together with other therapeutic approaches are currently being designed and assessed. In this review, recent progress in the therapeutic options targeting survivin for cancer treatment is analyzed. Direct survivin inhibitors and their current development status are explored. Besides, the major signaling pathways implicated in survivin regulation are described and different therapeutic approaches involving survivin indirect inhibition are evaluated. Finally, promising novel inhibitors under preclinical or clinical evaluation as well as challenges of developing survivin inhibitors as a new therapy for cancer treatment are discussed.

Radiation Sensitization of Basal Cell and Head and Neck Squamous Cell Carcinoma by the Hedgehog Pathway Inhibitor Vismodegib

Vismodegib, an inhibitor of the Hedgehog signaling pathway, is an approved drug for monotherapy in locally advanced or metastatic basal cell carcinoma (BCC). Data on combined modality treatment by vismodegib and radiation therapy, however, are rare. In the present study, we examined the radiation sensitizing effects of vismodegib by analyzing viability, cell cycle distribution, cell death, DNA damage repair and clonogenic survival in three-dimensional cultures of a BCC and a head and neck squamous cell carcinoma (HNSCC) cell line. We found that vismodegib decreases expression of the Hedgehog target genes glioma-associated oncogene homologue (GLI1) and the inhibitor of apoptosis protein (IAP) Survivin in a cell line- and irradiation-dependent manner, most pronounced in squamous cell carcinoma (SCC) cells. Furthermore, vismodegib significantly reduced proliferation in both cell lines, while additional irradiation only slightly further impacted on viability. Analyses of cell cycle distribution and cell death induction indicated a G1 arrest in BCC and a G2 arrest in HNSCC cells and an increased fraction of cells in SubG1 phase following combined treatment. Moreover, a significant rise in the number of phosphorylated histone-2AX/p53-binding protein 1 (γH2AX/53BP1) foci in vismodegib- and radiation-treated cells was associated with a significant radiosensitization of both cell lines. In summary, these findings indicate that inhibition of the Hedgehog signaling pathway may increase cellular radiation response in BCC and HNSCC cells.

Growth inhibition and chemo-radiosensitization of esophageal squamous cell carcinoma by survivin-shRNA lentivirus transfection

Esophageal cancer is one of the most common types of cancer worldwide, and it has a poor prognosis. Chemo-radiotherapy resistance and cancer relapse are among the most difficult issues in its treatment. Identifying the underlying molecular mechanisms is critical for developing novel therapies. Survivin has been previously suggested to be overexpressed in esophageal cancer cells. The present study identified that down-regulation of survivin sensitized esophageal cancer cells to chemo-radiotherapy. Consistent with previous studies, the present study indicated that survivin was overexpressed in 4 esophageal squamous carcinoma cell lines. Short hairpin RNA delivered by lentivirus successfully knocked down survivin in these cancer cell lines. Consequently, down-regulation of survivin impaired their colony-forming, migratory and invasive capabilities, while the overexpression of survivin in normal human esophagus epithelial cells improved their resistance to cisplatin, paclitaxel and radiation. Survivin knockdown induced apoptosis in esophageal cancer KYSE-150 and ECA-109 cell lines when exposed to the aforementioned chemo-radiotherapy treatments. These results indicate that survivin expression sustains growth in esophageal cancer cells, and confers resistance to chemo-radiotherapy. Targeted survivin ablation may be a promising strategy against esophageal tumor relapse and chemo-radioresistance.

Predicting response to sepantronium bromide (YM155), a survivin suppressant, by PET imaging with [11C]YM155

INTRODUCTION

Sepantronium bromide (YM155) is a survivin suppressant that induces apoptosis in tumor cells. Although YM155 induces tumor regression in various tumor types in vivo, phase I and II studies demonstrated responding and non-responding patient populations. We investigated ¹¹C-labeled YM155 ([¹¹C]YM155) used as a positron emission tomography (PET) tracer to assess whether tumor uptake of [¹¹C]YM155 correlated with its anti-tumor effect, thereby allowing identification of patients who would respond to YM155 treatment.

METHODS

(1) Uptake of YM155 was measured in 39 human cancer cell lines in vitro using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). (2) In vivo tumor uptake was assessed in xenografted mice and total body distribution was evaluated in a cynomolgus monkey using [¹¹C]YM155 with PET/computed tomography (CT) (mice) and PET (monkey) imaging.

RESULTS

Intracellular uptake of YM155 in human cancer cell lines correlated well with its in vitro efficacy measured by GI₅₀ (Pearson's r = -0.5709). Similarly, in vivo studies using tumor xenografted mice showed that tumors sensitive to YM155 demonstrated robust uptake of [¹¹C]YM155, whereas insensitive tumors demonstrated low uptake. In the monkey, the biodistribution of [¹¹C]YM155 indicated low accumulation in lung, breast, head, and neck and was only significant in organs involved with drug clearance: i.e. liver, kidneys, and bladder.

CONCLUSIONS

Robust uptake of [¹¹C]YM155 by a tumor appears to be a positive predictive marker for a good response to YM155. The findings suggest the potential utility of PET/CT imaging with [¹¹C]YM155 for selection of patients whose tumors are likely to respond to YM155.

ADVANCES IN KNOWLEDGE

YM155 efficacy correlated closely with its in vitro intracellular uptake and uptake on [¹¹C]YM155 PET imaging. [¹¹C]YM155 PET may predict tumor sensitivity to YM155.

IMPLICATIONS FOR PATIENT CARE

The concept that tumor response can be accurately predicted prior to chemotherapy should be exploited to improve cancer treatment outcomes through judicious patient selection. The small molecule sepantronium bromide (YM155), a survivin suppressant, has been developed for the treatment of several cancers, including non-Hodgkin lymphoma, lung cancer, and breast cancer. The preferentially high in vitro uptake of YM155 by YM155-sensitive cancer cells and the high in vivo uptake of [¹¹C]YM155 in YM155-sensitive tumors demonstrated by PET imaging suggest the potential utility of performing [¹¹C]YM155 PET to allow the identification of patients with YM155-sensitive tumors.

Hairpin-Hairpin Molecular Beacon Interactions for Detection of Survivin mRNA in Malignant SW480 Cells

Cancer biomarkers offer unique prospects for the development of cancer diagnostics and therapy. One of such biomarkers, protein survivin (Sur), exhibits strong antiapoptotic and proliferation-enhancing properties and is heavily expressed in multiple cancers. Thus, it can be utilized to provide new modalities for modulating the cell-growth rate, essential for effective cancer treatment. Herein, we have focused on the development of a new survivin-based cancer detection platform for colorectal cancer cells SW480 using a turn-on fluorescence oligonucleotide molecular beacon (MB) probe, encoded to recognize Sur messenger RNA (mRNA). Contrary to the expectations, we have found that both the complementary target oligonucleotide strands as well as the single- and double-mismatch targets, instead of exhibiting the anticipated simple random conformations, preferentially formed secondary structure motifs by folding into small-loop hairpin structures. Such a conformation may interfere with, or even undermine, the biorecognition process. To gain better understanding of the interactions involved, we have replaced the classical Tyagi-Kramer model of interactions between a straight target oligonucleotide strand and a hairpin MB with a new model to account for the hairpin-hairpin interactions as the biorecognition principle. A detailed mechanism of these interactions has been proposed. Furthermore, in experimental work, we have demonstrated an efficient transfection of malignant SW480 cells with SurMB probes containing a fluorophore Joe (SurMB-Joe) using liposomal nanocarriers. The green emission from SurMB-Joe in transfected cancer cells, due to the hybridization of the SurMB-Joe loop with Sur mRNA hairpin target, corroborates Sur overexpression. On the other hand, healthy human-colon epithelial cells CCD 841 CoN show only negligible expression of survivin mRNA. These experiments provide the proof-of-concept for distinguishing between the cancer and normal cells by the proposed hairpin-hairpin interaction method. The single nucleotide polymorphism sensitivity and a low detection limit of 26 nM (S/N = 3σ) for complementary targets have been achieved.

Anti-apoptotic Protein BIRC5 Maintains Survival of HIV-1-Infected CD4+ T Cells

HIV-1 infection of CD4⁺ T cells leads to cytopathic effects and cell demise, which is counter to the observation that certain HIV-1-infected cells possess a remarkable long-term stability and can persist lifelong in infected individuals treated with suppressive antiretroviral therapy (ART). Using quantitative mass spectrometry-based proteomics, we showed that HIV-1 infection activated cellular survival programs that were governed by BIRC5, a molecular inhibitor of cell apoptosis that is frequently overexpressed in malignant cells. BIRC5 and its upstream regulator OX40 were upregulated in productively and latently infected CD4⁺ T cells and were functionally involved in maintaining their viability. Moreover, OX40-expressing CD4⁺ T cells from ART-treated patients were enriched for clonally expanded HIV-1 sequences, and pharmacological inhibition of BIRC5 resulted in a selective decrease of HIV-1-infected cells in vitro. Together, these findings suggest that BIRC5 supports long-term survival of HIV-1-infected cells and may lead to clinical strategies to reduce persisting viral reservoirs.

Enhancement of chemosensitivity by simultaneously silencing of Mcl-1 and Survivin genes using small interfering RNA in human myelomonocytic leukaemia

Acute myeloid leukaemia (AML) is a genetically heterogeneous, severe and rapidly progressing disease triggered by blocking granulocyte or monocyte differentiation and maturation. Overexpression of myeloid cell leukaemia-1 (Mcl-1) and Survivin is associated with drug resistance, tumour progression and inhibition of apoptotic mechanisms in leukaemia and several cancers. In the present study, we examined the combined effect of etoposide and dual siRNA-mediated silencing of Mcl-1 and Survivin on U-937 AML cells. The AML cells were co-transfected with Mcl-1 and Survivin-specific siRNAs and genes silencing were confirmed by quantitative real-time PCR and Western blotting. Subsequently, MTT assay was used for the evaluation of cytotoxic effects by dual siRNA and etoposide on their own and in combination. For the studying of apoptosis, DNA-histone ELISA and annexin-V/FITC assays were performed. Co-transfection of Mcl-1 and Survivin siRNA significantly blocked their expression at the mRNA and protein levels, leading to the induction of apoptosis and strong inhibition of growth (p < .05). Besides, combined treatment of etoposide with Mcl-1 and Survivin siRNAs co-transfection leads to synergistically enhance etoposide-induced cytotoxic and apoptotic effects (p < .05). The results showed that Mcl-1 and Survivin play a major role in the U937 cells survival and their resistance relative to etoposide. Thus, Mcl-1 and Survivin can be considered as promising molecular targets for the treatment of AML. The combination treatment with etoposide, and siRNA-mediated silencing of corresponding genes may be a novel strategy in chemoresistance AML treatment.

Dihydromyricetin Induces Apoptosis and Reverses Drug Resistance in Ovarian Cancer Cells by p53-mediated Downregulation of Survivin

Ovarian cancer is one of the leading causes of death in gynecological malignancies, and the resistance to chemotherapeutic agents remains a major challenge to successful ovarian cancer chemotherapy. Dihydromyricetin (DHM), a natural flavonoid derived from Ampeopsis Grossdentata, has been widely applied in food industry and medicine for a long time. However, little is known about the effects of DHM on ovarian cancer and the underlying mechanisms. In this study, we demonstrated that DHM could effectively inhibit the proliferation of ovarian cancer cells and induce cell apoptosis. Survivin, an inhibitor of apoptosis (IAPs) family member, exhibited a decreased expression level after DHM treatment, which may be attributed to the activation of p53. Moreover, DHM markedly sensitized paclitaxel (PTX) and doxorubicin (DOX) resistant ovarian cancer cells to PTX and DOX by inhibiting survivin expression. Collectively, our findings highlight a previously undiscovered effect of DHM, which induces apoptosis and reverses multi-drug resistance against ovarian cancer cells through downregulation of survivin.

HSP90 inhibitor NVP-AUY922 induces cell apoptosis by disruption of the survivin in papillary thyroid carcinoma cells

Heat shock protein 90 (HSP90) is a molecular chaperone required for maintaining the stability and function of signal proteins that plays an important role in promoting the growth and survival of cancer cells. The incidence of papillary thyroid carcinoma (PTC) has been increasing in recent years. The effect of the novel non-geldanamycin HSP90 inhibitor NVP-AUY922 on apoptosis of papillary thyroid carcinoma cells has not been investigated. The influence of AUY922 on the survival of PTC cell lines K1 and IHH4 was evaluated. Cell viability was determined by cell counting kit method. Cell apoptosis was assessed by flow cytometry and western blotting and the potential mechanism was evaluated by western blotting and immunoprecipitation. Overexpression plasmid was transfected by Lipofectamine 2000 method. In K1 and IHH4 cell lines, after the treatment of AUY922, cell viability decreased, and the proportion of apoptosis cells increased. AUY922 caused the cleavage of PARP and caspase-3 proteins, and altered expression of survivin, which was a client protein of HSP90. In AUY922-treated cells, overexpression of survivin attenuated growth inhibition and cell apoptosis. The results indicate that AUY922 induces apoptotic cell death in PTC cells. Moreover, our findings demonstrate that AUY922 induced apoptosis by downregulating the expression of survivin protein in PTC cells.

Survivin downregulation using siRNA nanoliposomes inhibits cell proliferation and promotes the apoptosis of MHCC-97H hepatic cancer cells: An in vitro and in vivo study

At present, survivin is one of the most cancer-specific proteins that has been identified. The present study aimed to investigate the antitumor effects of novel survivin small interfering RNA (siRNA) nanoliposomes targeting survivin in human hepatocellular carcinoma MHCC-97H cells and xenograft mouse models. Survivin-targeted siRNA nanoliposomes were prepared and transfected into MHCC-97H cells and MHCC-97H-bearing nude mice. Survivin expression was analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. Cell viability was analyzed using an MTT assay and apoptosis was evaluated using Hoechst and Annexin V-fluorescein isothiocyanate/propidium iodide staining. Tumor growth in MHCC-97H-bearing mice was monitored following treatment and tumor samples were obtained for survivin expression analysis using RT-qPCR, western blotting and immunohistochemistry staining. Survivin expression levels were significantly downregulated by nanoliposome-mediated survivin siRNA delivery and this was associated with a significant inhibition of cell growth and an increase in the apoptosis of MHCC-97H cells. Downregulation of survivin expression using survivin siRNA nanoliposomes inhibited tumor growth in the MHCC-97H xenograft models without significant treatment-associated toxicity. Therefore, a cationic nanoliposome-based survivin siRNA delivery system was constructed and demonstrated to be efficient for survivin siRNA delivery in in vitro and in vivo studies. These results demonstrate that survivin downregulation was able to significantly attenuate cell proliferation and induce the apoptosis of MHCC-97H cells, as well as inhibit tumor cell growth in MHCC-97H xenograft models, indicating that survivin suppression using siRNA may contribute to the inhibition of tumor development by suppressing cell proliferation and promoting apoptosis.

Silencing of the mRNA-binding protein HuR increases the sensitivity of colorectal cancer cells to ionizing radiation through upregulation of caspase-2

Increased abundance of the mRNA-binding protein human antigen R (HuR) is a characteristic feature of many cancers and frequently associated with a high grade malignancy and therapy resistance. HuR elicits a broad cell survival program mainly by stabilizing or increasing the translation of mRNAs coding for anti-apoptotic effector proteins. Conversally, we previously identified the pro-apoptotic caspase-2 as a novel HuR target which is mainly regulated at the level of translation. In this study, we investigated whether siRNA-mediated HuR knockdown interferes with cell survival and radiation sensitivity by monitoring apoptosis, DNA repair and three-dimensional (3D) clonogenic survival. We observed a significant elevation in caspase-2 upon HuR depletion and in turn, a sensitization of colorectal DLD-1 and HCT-15 cells to radiation-induced apoptosis as implicated by the dose-dependent elevation of sub-G₁ phase cell entry and increased caspase-2, -3 and poly ADP-ribose polymerase (PARP)-cleavage, respectively. Coincidentally, HuR deficiency significantly elevated the number of radiation-induced γH2AX/53BP1-positive foci indicating an increase in DNA damage. Accordingly, the irradiation-dependent reduction in clonogenic cell survival was further impaired after knockdown of HuR. Importantly, HuR knockdown remained ineffective to radiation-induced cell responses after additional knockdown of caspase-2. Furthermore, by using RNA-pull down assay we demonstrate that irradiation (6 Gy) robustly increased HuR binding to caspase-2 mRNA. Collectively, sensitization of colon carcinoma cells to radiation-induced cell death and DNA-damage by HuR knockdown critically depends on caspase-2 and may represent a valuable approach to intervene with therapy resistance of colorectal cancer (CRC).

Fluorescence assay of dihydroorotate dehydrogenase that may become a cancer biomarker

We developed an assay method for measuring dihydroorotate dehydrogenase (DHODH) activity in cultured HeLa cells and fibroblasts, and in stage III stomach cancer and adjacent normal tissues from the same patient. The assay comprised enzymatic reaction of DHODH with a large amount of dihydroorotic acid substrate, followed by fluorescence (FL) detection specific for orotic acid using the 4-trifluoromethyl-benzamidoxime fluorogenic reagent. The DHODH activities in the biologically complex samples were readily measured by the assay method. Our data indicate significantly higher DHODH activity in HeLa cells (340 ± 25.9 pmol/10⁵ cells/h) than in normal fibroblasts (54.1 ± 7.40 pmol/10⁵ cells/h), and in malignant tumour tissue (1.10 ± 0.19 nmol/mg total proteins/h) than in adjacent normal tissue (0.24 ± 0.11 nmol/mg total proteins/h). This is the first report that DHODH activity may be a diagnostic biomarker for cancer.

Death receptor 5 (DR5) and a 5-gene apoptotic biomarker panel with significant differential diagnostic potential in colorectal cancer

High expression of Inhibitor of apoptosis proteins (IAPs) has been related to colorectal cancer (CRC) progression, resistance to treatment and poor prognosis. TRAIL (TNF-related apoptosis-inducing ligand) through its receptors DR4 (TRAIL-R1) and DR5 (TRAIL-R2) can selectively induce cancer cell apoptosis. The mRNA expression of DR4, DR5, c-IAP1, c-IAP2, XIAP and BIRC5/Survivin genes was examined in 100 paired (cancerous-normal) colorectal tissue specimens by real-time PCR, 50 of which were KRAS wild-type and 50 KRAS-mutant. DR5, XIAP and BIRC5/Survivin genes are significantly up-regulated (p < 0.0001, p = 0.012 and p = 0.0003, respectively), whereas c-IAP1 and c-IAP2 genes are significantly down-regulated at mRNA and protein levels in CRC (p < 0.0001 for both). ROC analyses showed that DR5, cIAP1 and cIAP2 expression has discriminatory value between CRC and normal tissue (AUC = 0.700, p < 0.0001 for DR5; AUC = 0.628, p = 0.011 for cIAP1; AUC = 0.673, p < 0.0001 for cIAP2). Combinatorial ROC analysis revealed the marginally fair discriminatory value of 5 genes as a panel (AUC = 0.685, p < 0.0001). Kaplan-Meier survival curves revealed significant association of cIAP2 down-regulation in CRC with lower overall survival probability of CRC patients (p = 0.0098). DR5, BIRC5/Survivin, XIAP, c-IAP1 and c-IAP2 mRNA expression are significantly deregulated in CRC and could provide a panel of markers with significant discriminatory value between CRC and normal colorectal tissue.

Survivin isoform expression in arsenic trioxide-treated acute promyelocytic leukemia cell line and patients: The odd expression pattern of survivin-2α

AIM

Survivin, an inhibitor of apoptosis protein, is overexpressed in most cancers and is associated with chemotherapy resistance, increased tumor recurrence and shorter patient survival. Several survivin splice variants have been described, and none of their expressions have been defined in acute promyelocytic leukemia (APL).

METHODS

Expression of the survivin gene isoforms (survivin, -2α, -2B, -ΔΕx3 and -3B) were analyzed in 50 peripheral blood and 19 bone marrow samples that were collected at different phases of the disease (diagnostic, remission and relapse) in APL patients treated with arsenic trioxide (ATO) as a front-line therapy. In addition, the human APL-derived cell line (NB4) was analyzed for the expression of survivin isoforms and capsase-3 in response to the ATO.

RESULTS

Survivin and its variants were overexpressed significantly in patient's bone marrow samples compared to peripheral blood or normal samples. Their expression was decreased after ATO treatment in both NB4 cells (except survivin-2α) and APL patients along with PML-RARα copy number reduction. Downregulation of survivin isoforms was associated with an increase in both caspase-3 gene expression and its enzymatic activity levels. In a patient who did not respond to ATO treatment, expression of survivin isoforms (except survivin-2α) were highly increased during the induction therapy.

CONCLUSION

Survivin isoforms are upregulated in APL patients, and their expression is diminished during the ATO treatment. In addition, overexpression of survivin and its variants (except survivin-2α) are associated with unfavorable results, suggesting that they may play an important role in mechanisms underlying the resistance of APL cells to ATO.

Role of survivin expression in predicting biochemical recurrence after radical prostatectomy: a multi-institutional study

OBJECTIVE

To assess the association of survivin expression with clinicopathological features and biochemical recurrence (BCR) after radical prostatectomy (RP) in a large multi-institutional cohort.

METHODS

Survivin expression was evaluated by immunohistochemistry on a tissue microarray of RP cores from 3 117 patients. Survivin expression was considered altered when at least 10% of the tumour cells stained positive. The association of altered survivin expression with BCR was evaluated using Cox proportional hazards regression models.

RESULTS

Survivin expression was altered in 1 330 patients (42.6%). Altered expression was associated with higher Gleason score on RP (P = 0.001), extracapsular extension (P = 0.019), seminal vesicle invasion (P < 0.001) and lymph node metastases (P = 0.009). The median (interquartile range) follow-up was 38 (21-66) months. Patients with altered survivin expression had a shorter BCR-free survival time than those with normal expression (5-year BCR-free survival estimates: 74.7 vs 79.0%; P = 0.008). Altered survivin expression did not retain its prognostic value, however, after adjustment for the effect of established clinicopathological factors (P = 0.73). Subgroup analyses also showed no independent prognostic value of survivin.

CONCLUSIONS

Survivin expression is commonly altered in patients undergoing RP. Altered survivin expression is associated with the clinicopathological features of biologically and clinically aggressive PCa. Survivin expression was associated with BCR only in univariable analysis, limiting its value in daily clinical decision-making.

Combination Nanopreparations of a Novel Proapoptotic Drug - NCL-240, TRAIL and siRNA

PURPOSE

To develop a multifunctional nanoparticle system carrying a combination of pro-apoptotic drug, NCL-240, TRAIL [tumor necrosis factor-α (TNF-α)-related apoptosis-inducing ligand] and anti-survivin siRNA and to test the combination preparation for anti-cancer effects in different cancer cells.

METHODS

Polyethylene glycol-phosphoethanolamine (PEG-PE) - based polymeric micelles were prepared carrying NCL-240. These micelles were used in combination with TRAIL-conjugated micelles and anti-survivin siRNA-S-S-PE containing micelles. All the micelles were characterized for size, zeta potential, and drug encapsulation efficiency. Different cancer cells were used to study the cytotoxicity potential of the individual as well as the combination formulations. Other cell based assays included cellular association studies of transferrin-targeted NCL-240 micelles and study of cellular survivin protein downregulation by anti-survivin siRNA-S-S-PE containing micelles.

RESULTS

NCL-240 micelles and the combination NCL-240/TRAIL micelles significantly increased cytotoxicity in the resistant strains of SKOV-3, MCF-7 and A549 as compared to free drugs or single drug formulations. The NCL-240/TRAIL micelles were also more effective in NCI/ADR-RES cancer cell spheroids. Anti-survivin siRNA micelles alone displayed a dose-dependent reduction in survivin protein levels in A2780 cells. Treatment with NCL-240/TRAIL after pre-incubation with anti-survivin siRNA inhibited cancer cell proliferation. Additionally, a single multifunctional system composed of NCL-240/TRAIL/siRNA PM also had significant cytotoxic effects in vitro in multiple cell lines.

CONCLUSION

These results demonstrate the efficacy of a combination of small-molecule PI3K inhibitors, TRAIL, and siRNA delivered by micellar preparations in multiple cancer cell lines.

Survivin and XIAP: two valuable biomarkers in medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) accounts for ∼5% of all thyroid malignancies. To date, surgery is the first-line therapy with curative intention. However, for advanced MTC, conventional chemotherapeutic agents do not provide convincing results. Therefore, the identification of biomarkers that can be antagonised by small-molecule therapeutics may lead to novel encouraging treatment options.

Methods:

Seventy-nine patients with surgically resected and histologically confirmed MTC were included in this study. Tissue microarrays were constructed to assess the relationship between inhibitor of apoptosis proteins (IAPs) survivin or XIAP expression levels and clinicopathological variables as well as overall survival.

Results:

High survivin or XIAP expression was associated with an advanced T-stage and metastatic disease. Whereas tissue expression levels of survivin correlated with serum calcitonin levels, XIAP was overexpressed in the subgroup of patients with sporadic MTC. Both IAPs were negatively associated with patient survival in the multivariate Cox regressions analysis (survivin: hazard ratio (HR) 1.62; 95% confidence interval (CI): 1.21–2.16; P=0.001; XIAP: HR 1.78; 95% CI: 1.16–2.72; P=0.008).

Conclusions:

Survivin and XIAP demonstrate distinct expression patterns in MTCs, which are associated with advanced disease and poor prognosis. We thus provide first evidence that both IAPs might serve as viable targets in patients with MTC.

T-Type Ca2+ Channel Inhibition Sensitizes Ovarian Cancer to Carboplatin

Ovarian cancer is the deadliest gynecologic cancer, due in large part to the diagnosis of advanced stage disease, the development of platinum resistance, and inadequate treatment alternatives. Recent studies by our group and others have shown that T-type calcium (Ca(2+)) channels play a reinforcing role in cancer cell proliferation, cell-cycle progression, and apoptosis evasion. Therefore, we investigated whether T-type Ca(2+) channels affect ovarian tumor growth and response to platinum agents. Inhibition of T-type Ca(2+) channels with mibefradil or by silencing expression resulted in growth suppression in ovarian cancer cells with a simultaneous increase in apoptosis, which was accompanied by decreased expression of the antiapoptotic gene survivin (BIRC5). Analysis of intracellular signaling revealed mibefradil reduced AKT phosphorylation, increased the levels and nuclear retention of FOXO transcription factors that repress BIRC5 expression, and decreased the expression of FOXM1, which promotes BIRC5 expression. Combining carboplatin with mibefradil synergistically increased apoptosis in vitro. Importantly, mibefradil rendered platinum-resistant ovarian tumors sensitive to carboplatin in a mouse model of peritoneal metastasis. Together, the data provide rationale for future use of T-type channel antagonists together with platinum agents for the treatment of ovarian cancer.

Association between survivin genetic polymorphisms and epidermal growth factor receptor mutation in non-small-cell lung cancer

Survivin is an anti-apoptotic protein that is implicated in the regulation of apoptosis and cell cycle in various types of cancers. The current study explored the effect of survivin gene polymorphisms and EGFR mutations in non-small-cell lung carcinoma (NSCLC) patients. A total of 360 participants, including 291 adenocarcinoma lung cancer and 69 squamous cell carcinoma lung cancer patients, were selected for the analysis of three survivin genetic variants (survivin -31, +9194, and +9809) by using real-time PCR genotyping. The results indicated that GC+CC genotypes of survivin -31 were significant association with EGFR mutation in lung adenocarcinoma patients (adjusted odds ratio=3.498, 95% CI = 1.171-10.448; p<0.01). Moreover, The GC+CC genotypes of survivin -31 were associated with EGFR L858R mutation but not in exon 19 in-frame deletions. Furthermore, among patients in exon 19 in-frame deletions, those who have at least one polymorphic G allele of survivin -31 have an increased incidence to develop late-stage when compared with those patients homozygous for C/C (OR, 4.800; 95% CI, 1.305-17.658). In conclusion, our results showed that survivin genetic variants were related to EGFR mutation in lung adenocarcinoma patients and might contribute to pathological development to NSCLC.

Indirect p53-dependent transcriptional repression of Survivin, CDC25C, and PLK1 genes requires the cyclin-dependent kinase inhibitor p21/CDKN1A and CDE/CHR promoter sites binding the DREAM complex

The transcription factor p53 is central to cell cycle control by downregulation of cell cycle-promoting genes upon cell stress such as DNA damage. Survivin (BIRC5), CDC25C, and PLK1 encode important cell cycle regulators that are repressed following p53 activation. Here, we provide evidence that p53-dependent repression of these genes requires activation of p21 (CDKN1A, WAF1, CIP1). Chromatin immunoprecipitation (ChIP) data indicate that promoter binding of B-MYB switches to binding of E2F4 and p130 resulting in a replacement of the MMB (Myb-MuvB) by the DREAM complex. We demonstrate that this replacement depends on p21. Furthermore, transcriptional repression by p53 requires intact DREAM binding sites in the target promoters. The CDE and CHR cell cycle promoter elements are the sites for DREAM binding. These elements as well as the p53 response of Survivin, CDC25C, and PLK1 are evolutionarily conserved. No binding of p53 to these genes is detected by ChIP and mutation of proposed p53 binding sites does not alter the p53 response. Thus, a mechanism for direct p53-dependent transcriptional repression is not supported by the data. In contrast, repression by DREAM is consistent with most previous findings and unifies models based on p21-, E2F4-, p130-, and CDE/CHR-dependent repression by p53. In conclusion, the presented data suggest that the p53-p21-DREAM-CDE/CHR pathway regulates p53-dependent repression of Survivin, CDC25C, and PLK1.

Radio-Immunotherapy-Induced Immunogenic Cancer Cells as Basis for Induction of Systemic Anti-Tumor Immune Responses - Pre-Clinical Evidence and Ongoing Clinical Applications

Radiotherapy (RT) primarily aims to locally destroy the tumor via the induction of DNA damage in the tumor cells. However, the so-called abscopal, namely systemic and immune–mediated, effects of RT move over more and more in the focus of scientists and clinicians since combinations of local irradiation with immune therapy have been demonstrated to induce anti-tumor immunity. We here summarize changes of the phenotype and microenvironment of tumor cells after exposure to irradiation, chemotherapeutic agents, and immune modulating agents rendering the tumor more immunogenic. The impact of therapy-modified tumor cells and damage-associated molecular patterns on local and systemic control of the primary tumor, recurrent tumors, and metastases will be outlined. Finally, clinical studies affirming the bench-side findings of interactions and synergies of radiation therapy and immunotherapy will be discussed. Focus is set on combination of radio(chemo)therapy (RCT) with immune checkpoint inhibitors, growth factor inhibitors, and chimeric antigen receptor T-cell therapy. Well-deliberated combination of RCT with selected immune therapies and growth factor inhibitors bear the great potential to further improve anti-cancer therapies.

F-box protein interactions with the hallmark pathways in cancer

F-box proteins (FBP) are the substrate specifying subunit of Skp1-Cul1-FBP (SCF)-type E3 ubiquitin ligases and are responsible for directing the ubiquitination of numerous proteins essential for cellular function. Due to their ability to regulate the expression and activity of oncogenes and tumour suppressor genes, FBPs themselves play important roles in cancer development and progression. In this review, we provide a comprehensive overview of FBPs and their targets in relation to their interaction with the hallmarks of cancer cell biology, including the regulation of proliferation, epigenetics, migration and invasion, metabolism, angiogenesis, cell death and DNA damage responses. Each cancer hallmark is revealed to have multiple FBPs which converge on common signalling hubs or response pathways. We also highlight the complex regulatory interplay between SCF-type ligases and other ubiquitin ligases. We suggest six highly interconnected FBPs affecting multiple cancer hallmarks, which may prove sensible candidates for therapeutic intervention.

The SMAC mimetic BV6 sensitizes colorectal cancer cells to ionizing radiation by interfering with DNA repair processes and enhancing apoptosis

Background

In the present study, we aimed to investigate the effect of counteracting inhibitor of apoptosis (IAP) proteins using the small molecule Second Mitochondria-derived Activator of Caspase (SMAC) mimetic BV6 in combination with ionizing radiation on apoptosis, cell cycle regulation, DNA double-strand break (DSB) repair, three-dimensional (3D) clonogenic survival and expression of IAPs in colorectal carcinoma cells.

Material and methods

Colorectal cancer cell lines (HCT-15, HT-29, SW480) were subjected to BV6 treatment (0–4 μM) with or without irradiation (2–8 Gy, single dose) followed by MTT, Caspase 3/7 activity, γH2AX/53BP1 foci assays, AnnexinV staining, cell cycle analysis, 3D colony forming assays and Western blotting (cellular IAP1 (cIAP1) and cIAP2, Survivin, X-linked IAP (XIAP)).

Results

BV6 treatment decreased cell viability and significantly increased irradiation-induced apoptosis as analyzed by Caspase 3/7 activity, AnnexinV-positive and subG1 phase cells. While basal 3D clonogenic survival was decreased in a cell line-dependent manner, BV6 significantly enhanced cellular radiosensitivity of all cell lines in a concentration-dependent manner and increased the number of radiation-induced γH2AX/53BP1-positive foci. Western blot analysis revealed a markedly reduced cIAP1 expression at 4 h after BV6 treatment in all cell lines, a substantial reduction of XIAP expression in SW480 and HT-29 cells at 24 h and a slightly decreased cIAP2 expression in HCT-15 cells at 48 h after treatment. Moreover, single or double knockdown of cIAP1 and XIAP resulted in significantly increased residual γH2AX/53BP1-positive foci 24 h after 2 Gy and radiosensitization relative to control small interfering RNA (siRNA)-treated cells.

Conclusion

The SMAC mimetic BV6 induced apoptosis and hampered DNA damage repair to radiosensitize 3D grown colorectal cancer cells. Our results demonstrate IAP targeting as a promising strategy to counteract radiation resistance of colorectal cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-015-0507-4) contains supplementary material, which is available to authorized users.