Association of p53 gene alterations with the expression of antiapoptotic survivin splice variants in breast cancer

Survivin Splice Variant 2β Enhances Pancreatic Ductal Adenocarcinoma Resistance to Gemcitabine

Background

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with poor prognosis, as it is difficult to predict or circumvent, and it develops chemoresistance quickly. One cellular mechanism associated with chemoresistance is alternative splicing dysfunction, a process through which nascent mRNA is spliced into different isoforms. Survivin (Baculoviral IAP Repeat-Containing Protein 5 (BIRC5)), a member of the inhibitor of apoptosis (IAP) protein family and a cell cycle-associated oncoprotein, is overexpressed in most cancers and undergoes alternative splicing (AS) to generate six different splicing isoforms.

Methods

To determine if survivin splice variants (SSV) could be involved in PDAC chemoresistance, a Gemcitabine (Gem) resistant (GR) cell line, MIA PaCa-2 GR, was created and assessed for its SSV levels and their potential association with GR. Cross-resistance was assessed in MIA-PaCa-2 GR cells to FIRINOX (5-fluorouracil (5-FU), irinotecan, and oxaliplatin). Once chemoresistance was confirmed, RT-qPCR was used to assess the expression of survivin splice variants (SSVs) in PDAC cell lines. To confirm the effect of SSVs on chemoresistance, we used siRNA to knockdown all SSVs or SSV 2β.

Results

The MIA PaCa-2 GR cell line was 40 times more resistant to Gem and revealed increased resistance to FIRINOX (5-fluorouracil (5-FU), irinotecan, and oxaliplatin); when compared to the parental MIA-PaCa-2 cells. RT-qPCR studies revealed an 8-fold relative expression increase in SSV 2β and a 2- to 8-fold increase in the other five SSVs in the GR cells. Knockdown of all SSV or SSV 2β only, using small inhibitory RNA (siRNA), sensitized the GR cells to Gem, indicating that these SSVs play a role in PDAC chemoresistance.

Conclusion

These findings provide evidence for the potential role of SSV 2β and other SSVs in innate and acquired PDAC chemoresistance. We also show that the expression of SSVs is not affected by the type of chemoresistance, therefore targeting survivin splice variants in combination with chemotherapy could benefit a wide range of patients.

Survivin in Breast Cancer: A Review

Breast cancer is the most frequently diagnosed cancer in women and ranks second among causes for cancer-related death in women. Gene technology has led to the recognition that breast cancer is a heterogeneous disease composed of different biological subtypes, and genetic profiling enables the response to chemotherapy to be predicted. This fact emphasizes the importance of selecting sensitive diagnostic and prognostic markers in the early disease stage and more efficient targeted treatments for this disease. One such prognostic marker appears to be survivin. Many studies have shown that survivin is strongly expressed in different types of cancers. Its overexpression has been demonstrated in breast cancer, and high activity of the survivin gene has been associated with a poor prognosis and worse survival rates.

Survivin is critically involved in VEGFR2 signaling-mediated esophageal cancer cell survival

Vascular endothelial growth factor (VEGF) signaling promotes angiogenesis by stimulating the migration and proliferation of endothelial cells. The aim of this study was to investigate the expression of Survivin and VEGF receptor 1/2/3 (VEGFR 1/2/3) in esophageal carcinoma tissues (ECTs), and to explore the therapy effect of the suppression of VEGFR2 signaling. Here, we found that VEGFR2 and Survivin had high expressions and a significant correlation (r = 0.874, P < 0.002) in ECTs. Further, we found that VEGFR2 signaling could activate the AKT1/MDM2/Survivin pathway. The inhibition of VEGFR2 signaling with the XL184 treatment downregulated the phosphorylation of AKT1 and MDM2, and then, increased the activation of Caspase 3/7, resulting in the reduction of cell viability and the apoptosis of HUVECs. Additionally, in the esophageal tumor model, the tumor growth was significantly suppressed by blocking Survivin and the suppression of tumor growth was more effective in the combined treatment by blocking Survivin and Bcl-xl/Bcl-2. Our data thus revealed that Survivin in the signal downstream of VEGFR2 played an important role in esophageal cancer cell survival and might be a potential candidate target for the combined therapy for esophageal cancer.

Screening for Multiple Autoantibodies in Plasma of Patients with Breast Cancer

BACKGROUND/AIM

Autoantibodies have potential as circulating biomarkers for early cancer detection. This study aimed to screen for known autoantibodies in human plasma using an Autoantibody Profiling System (APS) and quantify the levels in plasma of donors with/without breast cancer.

MATERIALS AND METHODS

Plasma from nine female donors diagnosed with breast cancer (test group) and nine matched donors with no personal history of cancer (reference group) were screened with an APS containing probes for 30 autoantibodies. Autoantibody levels ≥1.5 times the mean concentration of the group were considered elevated, and test/reference ratios ≥1.3 were considered higher in the test group compared to the reference group.

RESULTS

Twenty percent of the probes detected elevated levels of autoantibodies against proteins involved in different cancer mechanisms. Amongst these, the levels of autoantibodies against interleukin 29 (IL29), osteoprotegerin (OPG), survivin (SUR), growth hormone (GRH) and resistin (RES) were significantly higher in the cancer group compared to the reference group (p<0.05), whereas the level of autoantibody against cytotoxic T-lymphocyte associated antigen-4 (CTLA4) was not significantly different between the two groups (p=0.38).

CONCLUSION

Disease-relevant autoantibodies were detected in the plasma of patients with breast cancer and donors without breast cancer. This means that identifying the type and level of autoantibodies in samples will be important in determining their significance in the disease process. A microtiter plate-based array system could be a fast and inexpensive screening method for identifying and quantifying autoantibodies in human plasma.

Bayesian nonparametric discovery of isoforms and individual specific quantification

Most human protein-coding genes can be transcribed into multiple distinct mRNA isoforms. These alternative splicing patterns encourage molecular diversity, and dysregulation of isoform expression plays an important role in disease etiology. However, isoforms are difficult to characterize from short-read RNA-seq data because they share identical subsequences and occur in different frequencies across tissues and samples. Here, we develop biisq, a Bayesian nonparametric model for isoform discovery and individual specific quantification from short-read RNA-seq data. biisq does not require isoform reference sequences but instead estimates an isoform catalog shared across samples. We use stochastic variational inference for efficient posterior estimates and demonstrate superior precision and recall for simulations compared to state-of-the-art isoform reconstruction methods. biisq shows the most gains for low abundance isoforms, with 36% more isoforms correctly inferred at low coverage versus a multi-sample method and 170% more versus single-sample methods. We estimate isoforms in the GEUVADIS RNA-seq data and validate inferred isoforms by associating genetic variants with isoform ratios.

Alternative splicing leads to transcript isoform diversity. Here, Aguiar et al. develop biisq, a Bayesian nonparametric approach to discover and quantify isoforms from RNA-seq data.

Clinical Significance and Biological Role of HuR in Head and Neck Carcinomas

Background

Hu-antigen R (HuR) is a posttranscriptional regulator of several target mRNAs, implicated in carcinogenesis. This review aims to present the current evidence regarding the biological role and potential clinical significance of HuR in head and neck carcinomas.

Methods

The existing literature concerning HuR expression and function in head and neck carcinomas is critically presented and summarised.

Results

HuR is expressed in the majority of the examined samples, showing higher cytoplasmic levels in malignant or premalignant cases. Moreover, HuR modulates several genes implicated in biological processes important for malignant transformation, growth, and invasiveness. HuR seems to be an adverse prognosticator in patients with OSCCs, whereas a correlation with a more aggressive phenotype is reported in several types of carcinomas.

Conclusions

A consistent role of HuR in the carcinogenesis and progression of head and neck carcinomas is suggested; nevertheless, further studies are warranted to expand the present information.

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.

Splicing imbalances in basal-like breast cancer underpin perturbation of cell surface and oncogenic pathways and are associated with patients' survival

Despite advancements in the use of transcriptional information to understand and classify breast cancers, the contribution of splicing to the establishment and progression of these tumours has only recently starting to emerge. Our work explores this lesser known landscape, with special focus on the basal-like breast cancer subtype where limited therapeutic opportunities and no prognostic biomarkers are currently available. Using ExonArray analysis of 176 breast cancers and 9 normal breast tissues we demonstrate that splicing levels significantly contribute to the diversity of breast cancer molecular subtypes and explain much of the differences compared with normal tissues. We identified pathways specifically affected by splicing imbalances whose perturbation would be hidden from a conventional gene-centric analysis of gene expression. We found that a large fraction of them involve cell-to-cell communication, extracellular matrix and transport, as well as oncogenic and immune-related pathways transduced by plasma membrane receptors. We identified 247 genes in which splicing imbalances are associated with clinical patients’ outcome, whilst no association was detectable at the gene expression level. These include the signaling gene TGFBR1, the proto-oncogene MYB as well as many immune-related genes such as CCR7 and FCRL3, reinforcing evidence for a role of immune components in influencing breast cancer patients’ prognosis.

Survivin splice variants and their diagnostic significance

Survivin plays a crucial role in cell division particularly during the development of the fetus, in the onset and progression of most tumors and is found expressed in a few terminally differentiated cells. Altogether, there are ten splice variants of survivin, some of which are not yet satisfactorily characterized. Several isoforms may undergo homo/heterodimerization, particularly with the wild-type survivin to elicit a variety of biological functions. The detection of survivin and its splice variants not only suggests the onset, maintenance, and progression of cancer, but also the stage of certain cancers. Recent studies demonstrate that the presence of survivin in urine and blood samples of patients may suggest urogenital and bladder cancer hematologic malignancies, respectively. The expression of the survivin-3α splice variant is indicative of the onset and progression of breast cancer. Several companies have developed cancer diagnostic kits using survivin for detection of cancer. Some are also engaged in fine-tuning the type and stage-specific diagnosis of cancer based on survivin, its splice variants with and without other markers, such as hyaluronidase. Briefly, survivin and its splice variants hold a great biological significance, particularly in the diagnosis of cancer.

Survivin family proteins as novel molecular determinants of doxorubicin resistance in organotypic human breast tumors

Introduction

The molecular determinants of breast cancer resistance to first-line anthracycline-containing chemotherapy are unknown.

Methods

We examined the response to doxorubicin of organotypic cultures of primary human breast tumors ex vivo with respect to cell proliferation, DNA damage and modulation of apoptosis. Samples were analyzed for genome-wide modulation of cell death pathways, differential activation of p53, and the role of survivin family molecules in drug resistance. Rational drug combination regimens were explored by high-throughput screening, and validated in model breast cancer cell types.

Results

Doxorubicin treatment segregated organotypic human breast tumors into distinct Responder or Non Responder groups, characterized by differential proliferative index, stabilization of p53, and induction of apoptosis. Conversely, tumor histotype, hormone receptor or human epidermal growth factor receptor-2 (HER2) status did not influence chemotherapy sensitivity. Global analysis of cell death pathways identified survivin and its alternatively spliced form, survivin-ΔEx3 as uniquely overexpressed in Non Responder breast tumors. Forced expression of survivin-ΔEx3 preserved cell viability and prevented doxorubicin-induced apoptosis in breast cancer cell types. High-throughput pharmacologic targeting of survivin family proteins with a small-molecule survivin suppressant currently in the clinic (YM155) selectively potentiated the effect of doxorubicin, but not other chemotherapeutics in breast cancer cell types, and induced tumor cell apoptosis.

Conclusions

Survivin family proteins are novel effectors of doxorubicin resistance in chemotherapy-naive breast cancer. The incorporation of survivin antagonist(s) in anthracycline-containing regimens may have improved clinical activity in these patients.

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.

Transcriptional regulation of the survivin gene

Survivin, a small member of the inhibitors of the apoptosis protein family, is highly deregulated in cancer. It is weakly expressed in normal tissues but very strongly expressed in malignant lesions. Survivin is involved in cell-cycle progression, especially in the G2/M transition, and has anti-apoptotic activity, which correlates with its strong expression in cases with a poor cancer treatment response and poor outcomes. Several therapies that target the survivin transcript or protein are currently being tested in clinical trials. However, focusing new therapies on the origins of survivin overexpression and targeting these upstream deregulations could be more effective. For this reason, it seems important to make an inventory of the transcriptional (de)regulation of survivin. This review will gather the important points concerning the regulation of survivin mRNA expression: structure of the survivin promoter, epigenetic modifications and genetic abnormalities, transcription factors, and signalling pathways that affect survivin mRNA expression.

Survivin-3B potentiates immune escape in cancer but also inhibits the toxicity of cancer chemotherapy

Dysregulation in patterns of alternative RNA splicing in cancer cells is emerging as a significant factor in cancer pathophysiology. In this study, we investigated the little known alternative splice isoform survivin-3B (S-3B) that is overexpressed in a tumor-specific manner. Ectopic overexpression of S-3B drove tumorigenesis by facilitating immune escape in a manner associated with resistance to immune cell toxicity. This resistance was mediated by interaction of S-3B with procaspase-8, inhibiting death-inducing signaling complex formation in response to Fas/Fas ligand interaction. We found that S-3B overexpression also mediated resistance to cancer chemotherapy, in this case through interactions with procaspase-6. S-3B binding to procaspase-6 inhibited its activation despite mitochondrial depolarization and caspase-3 activation. When combined with chemotherapy, S-3B targeting in vivo elicited a nearly eradication of tumors. Mechanistic investigations identified a previously unrecognized 7-amino acid region as responsible for the procancerous properties of survivin proteins. Taken together, our results defined S-3B as an important functional actor in tumor formation and treatment resistance.

Clinico-pathologic relevance of Survivin splice variant expression in cancer

Survivin is a member of the inhibitor of apoptosis (IAP) family and has multifunctional properties that include aspects of proliferation, invasion and cell survival control. Survivin is a promising candidate for targeted cancer therapy as its expression is associated with poor clinical outcome, more aggressive clinico-pathologic features, and resistance to radiation and chemotherapy. In the present review the different properties of the Survivin splice variants are discussed and their activities correlated with different aspects of cancer cell biology, to include subcellular location. Special emphasis is placed on our current understanding of these Survivin splice variants influence on each other and on the phenotypic responses to therapy that they may control.

Polypeptide chain release factor eRF3 is a novel molecular partner of survivin

The eukaryotic class II polypeptide chain release factor (eRF3) is an eRF1- and ribosome-dependent GTPase involved in translation termination of protein biosynthesis. eRF3 is a multifunctional protein that is also involved in chromosomal segregation and cytokinesis during mitosis. Survivin is a member of the inhibitor of apoptosis protein (IAP) family that is involved in the organisation of spindle and cell apoptosis. Interaction between survivin and eRF3a-F3 or eRF3b, encoded by the GSPT1 and GSPT2 genes, respectively, was confirmed using yeast two-hybrid (Y2H) and pull-down assays in vitro, and co-immunoprecipitation in vivo. The domains involved in the formation of the survivin-eRF3s complex have been identified. The sites on survivin that interact with eRF3 are located in the baculovirus IAP repeat domain (residues 65-76), which forms a beta-strand structure with an overall negative charge. The sites on eRF3 that interact with survivin were localised to the N-terminal domain(NTD; residues 131-200). Cell localisation experiments indicate that both factors are in the nucleus, suggesting that they cooperatively function in nuclear processes.

microRNA-16 represses colorectal cancer cell growth in vitro by regulating the p53/survivin signaling pathway

Dysregulated expression of microRNAs (miRNA) is a hallmark of cancer. miR-16 has been reported to be downregulated and to act as a tumor suppressor in different cancer types. In the present study, we sought to investigate the possible roles and mechanisms of miR-16 and its relationship with p53 and survivin in CRC cells. We showed that miR-16 was downregulated in 67% of CRC tissues and was correlated with the degree of histological differentiation. Experiments in vitro showed that overexpression of miR-16 inhibited the proliferation and induced apoptosis of CRC cells through the intrinsic apoptosis pathway. We further showed that miR-16 repressed survivin expression at both the mRNA and protein levels and the survivin gene was a direct target of miR-16. In addition, miR-16 reduced p53 expression and p53 increased miR-16 levels, with downregulation of miR-16 targets survivin, cyclin D1 and CDK6. Our findings suggest that miR-16 represses colorectal cancer cell growth in vitro by regulating the p53/survivin signaling pathway. Our findings provide further evidence for the involvement of dysregulated miRNAs in CRC, and miR-16 could serve as a molecular target for CRC therapy.

Only missense mutations affecting the DNA binding domain of p53 influence outcomes in patients with breast carcinoma

The presence of a TP53 gene mutation can influence tumour response to some treatments, especially in breast cancer. In this study, we analysed p53 mRNA expression, LOH at 17p13 and TP53 mutations from exons 2 to 11 in 206 patients with breast carcinoma and correlated the results with disease-free and overall survival. The observed mutations were classified according to their type and location in the three protein domains (transactivation domain, DNA binding domain, oligomerization domain) and correlated with disease-free and overall survival. In our population, neither p53 mRNA expression nor LOH correlated with outcome. Concerning TP53 mutations, 27% of tumours were mutated (53/197) and the presence of a mutation in the TP53 gene was associated with worse overall survival (p = 0.0026) but not with disease-free survival (p = 0.0697), with median survival of 80 months and 78 months, respectively. When alterations were segregated into mutation categories and locations, and related to survival, tumours harbouring mutations other than missense mutations in the DNA binding domain of P53 had the same survival profiles as wild-type tumours. Concerning missense mutations in the DNA binding domain, median disease-free and overall survival was 23 months and 35 months, respectively (p = 0.0021 and p<0.0001, respectively), compared with 78 and 80 months in mutated tumours overall. This work shows that disease-free and overall survival in patients with a frameshift mutation of TP53 or missense mutation in the oligomerization domain are the same as those in wild-type TP53 patients.

The rebel angel: mutant p53 as the driving oncogene in breast cancer

Breast cancer is the most frequent invasive tumor diagnosed in women, causing over 400 000 deaths yearly worldwide. Like other tumors, it is a disease with a complex, heterogeneous genetic and biochemical background. No single genomic or metabolic condition can be regarded as decisive for its formation and progression. However, a few key players can be pointed out and among them is the TP53 tumor suppressor gene, commonly mutated in breast cancer. In particular, TP53 mutations are exceptionally frequent and apparently among the key driving factors in triple negative breast cancer -the most aggressive breast cancer subgroup-whose management still represents a clinical challenge. The majority of TP53 mutations result in the substitution of single aminoacids in the central region of the p53 protein, generating a spectrum of variants ('mutant p53s', for short). These mutants lose the normal p53 oncosuppressive functions to various extents but can also acquire oncogenic properties by gain-of-function mechanisms. This review discusses the molecular processes translating gene mutations to the pathologic consequences of mutant p53 tumorigenic activity, reconciling cell and animal models with clinical outcomes in breast cancer. Existing and speculative therapeutic methods targeting mutant p53 are also discussed, taking into account the overlap of mutant and wild-type p53 regulatory mechanisms and the crosstalk between mutant p53 and other oncogenic pathways in breast cancer. The studies described here concern breast cancer models and patients-unless it is indicated otherwise and justified by the importance of data obtained in other models.

Marked upregulation of Survivin and Aurora-B kinase is associated with disease progression in the myelodysplastic syndromes

BACKGROUND

Myelodysplastic syndromes are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis. Survivin is a member of the inhibitor of apoptosis family and suppresses apoptosis. Survivin also functions as a subunit of the chromosomal passenger complex for regulating mitosis with Aurora-B. Survivin and Aurora-B play an important role in maintaining genome stability. The aim of this study was to determine the role of Survivin and Aurora-B kinase in disease progression and prognosis of myelodysplastic syndromes.

DESIGN AND METHODS

We evaluated the expression levels of these two genes in CD34(+) cells prepared from 64 patients with myelodysplastic syndrome or leukemic blasts from 50 patients with de novo acute myeloid leukemia using quantitative real-time PCR.

RESULTS

Survivin and Aurora-B expression levels were highly correlated with the type of myelodysplastic syndrome, were much higher in refractory anemia with excess blasts-1, refractory anemia with excess blasts-2, and secondary acute myeloid leukemia following myelodysplastic syndrome than in normal control, and increased during disease progression. There was a significant correlation between these expression levels and the International Prognostic Scoring System. Interestingly, these levels were remarkably higher in patients with secondary acute myeloid leukemia following myelodysplastic syndromes than in those with de novo acute myeloid leukemia.

CONCLUSIONS

This is the first report showing that high levels of Survivin and Aurora-B kinase expression in CD34(+) cells are distinctive molecular features of high-risk myelodysplastic syndromes and secondary acute myeloid leukemia following myelodysplastic syndrome. Marked upregulation of Survivin and Aurora-B kinase may contribute to genetic instability and disease progression of myelodysplastic syndromes. Our data may explain why patients with high-risk myelodysplastic syndromes frequently show complex chromosomal abnormality.

An identical, complex TP53 mutation arising independently in two unrelated families with diverse cancer profiles: the complexity of interpreting cancer risk in carriers

Most inherited TP53 mutations have been identified in individuals with a family cancer predisposition syndrome, in which the activity of p53 mutants is severely reduced. However, germline p53 mutants in children with 'sporadic' adrenocortical or choroid plexus tumors exhibit a wide range of functional activity. Here, we demonstrate the occurrence of a complex germline TP53 mutation in two unrelated families with different cancer phenotypes, neither fulfilling the classic criteria for Li-Fraumeni syndrome. The TP53 mutation consists of a duplication of 7 bp in exon 4, resulting in a frame shift and premature stop signal. Haplotype analysis indicated that the mutation arose independently in the two families. Analysis of the DNA secondary structure predicts the TP53 mutation occurred within a hairpin loop. Additional germline complex mutations occurring within the same region of exon 4 have been identified in the IARC database. Our findings suggest that certain TP53 regions are prone to intrinsic genetic alterations, possibly through defects in DNA replication or repair. Further, carriers of the same TP53 mutation can have diverse cancer profiles, illustrating the complexity of genetic counseling and risk prediction.

Regulation of monocarboxylate transporter MCT1 expression by p53 mediates inward and outward lactate fluxes in tumors

The monocarboxylate transporter (MCT) family member MCT1 can transport lactate into and out of tumor cells. Whereas most oxidative cancer cells import lactate through MCT1 to fuel mitochondrial respiration, the role of MCT1 in glycolysis-derived lactate efflux remains less clear. In this study, we identified a direct link between p53 function and MCT1 expression. Under hypoxic conditions, p53 loss promoted MCT1 expression and lactate export produced by elevated glycolytic flux, both in vitro and in vivo. p53 interacted directly with the MCT1 gene promoter and altered MCT1 mRNA stabilization. In hypoxic p53(-/-) tumor cells, NF-κB further supported expression of MCT1 to elevate its levels. Following glucose deprivation, upregulated MCT1 in p53(-/-) cells promoted lactate import and favored cell proliferation by fuelling mitochondrial respiration. We also found that MCT1 expression was increased in human breast tumors harboring p53 mutations and coincident features of hypoxia, with higher MCT1 levels associated with poorer clinical outcomes. Together, our findings identify MCT1 as a target for p53 repression and they suggest that MCT1 elevation in p53-deficient tumors allows them to adapt to metabolic needs by facilitating lactate export or import depending on the glucose availability.

Survivin splice variants are not essential for mitotic progression or inhibition of apoptosis induced by doxorubicin and radiation

Survivin is a critical regulator of mitosis, and an inhibitor of apoptosis which is overexpressed in almost all cancers. In the current study, cell cycle profiles of normal proliferating human umbilical vein endothelial cells, prostate cancer, and lung cancer cell lines expressing varying levels of survivin and its splice variants were compared using a novel functional complementation assay. Defects in chromosome segregation and cytokinesis that were observed after depletion of endogenous survivin were not complemented by any of the survivin splice variants: survivin-2B, survivin-3B, survivin-ΔEx3, or survivin-2A when expressed exogenously at a level comparable to endogenous full-length survivin. Survivin variants were not detectable at the endogenous protein level. Cancer cells with higher levels of full-length survivin and survivin-2B expression, exhibited reduced caspase-3 activation following doxorubicin treatment and radiation. Whereas earlier studies focused on function and expression levels of survivin specific to cancer cells, the current study brings forward the essential role of survivin in normal dividing cells. Full-length survivin was found to be associated with Aurora-B kinase in the chromosomal passenger complex and depletion of survivin mimics mitotic phenotypes observed after Aurora-B kinase inhibition, in cancer as well as normal proliferating cells. Thus, our study establishes survivin as a marker of proliferation, rather than a cancer specific marker. Therefore, systemic therapeutic interventions targeting survivin will affect cancer as well as normal proliferating cells.

Association between survivin -31G > C promoter polymorphism and cancer risk: a meta-analysis

Survivin is an inhibitor of apoptosis protein and has a crucial role in the development of cancer. The survivin -31G>C (rs9904341) promoter polymorphism influences survivin expression and has been implicated in cancer risk. However, conflicting results have been published from studies on the association between survivin -31G>C polymorphism and the risk of cancer. To clarify the role of this polymorphism in cancer, we performed a meta-analysis of all available and relevant published studies, involving a total of 3485 cancer patients and 3964 control subjects. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations. The overall results indicated that the variant genotypes were associated with a significantly increased cancer risk (CC vs GG: OR=1.58, 95% CI=1.20-2.10; CC/GC vs GG: OR=1.23, 95% CI=1.00-1.51; CC vs GG/GC: OR=1.51, 95% CI=1.23-1.85). In the stratified analyses, significantly increased risk was associated with the Asian populations (CC vs GG: OR=1.67, 95% CI=1.16-2.40; CC vs GG/GC: OR=1.50, 95% CI=1.17-1.91). We also performed the analyses by cancer type, and no statistical association was observed. The results suggest that the survivin -31G>C promoter polymorphism might be associated with an increased risk of cancer, especially in the Asian populations.

Apoptosis gene signature of Survivin and its splice variant expression in breast carcinoma

Survivin, an anti-apoptotic protein, was described as strongly expressed in human cancers including breast cancer. However, little is known about the association between Survivin variants (Survivin-2B, Survivin-ΔEx3, Survivin-3B, and Survivin-2α) and the other apoptotic-related genes. In this study, we analyzed the apoptosis gene signature of Survivin and its variant expression in breast cancer. Human Apoptosis Gene Arrays were used to screen genes that could be associated with Survivin variants. Expression of the five transcripts was measured by RT-PCR in 135 breast carcinomas and Cox survival analysis was analyzed according to the patient outcome. Significant associations between Survivin transcripts and apoptotic genes were found. Interestingly, Survivin-3B variant showed major inverse correlations with pro-apoptotic genes. In addition, in vitro results indicated that overexpression of Survivin-3B strongly inhibits 5-fluorouracil/epirubicin/cyclophosphamide-induced apoptosis in breast tumor cell lines. In breast carcinomas, uni- and multivariate analysis showed patients with high level of Survivin-3B expression had a shorter overall (P=0.030 and P=0.042 respectively), and disease-free (P=0.024 and P=0.009) survival. Our data suggest that Survivin-3B contributes to cell survival through the anti-apoptotic pathway and that its expression level could be an important factor in determining therapeutic strategies for breast carcinoma.

Nuclear survivin expression is a positive prognostic factor in taxane-platinum-treated ovarian cancer patients

Background

Survivin is an inhibitor of apoptosis and a regulator of mitotic progression. TP53 protein is a negative transcriptional regulator of survivin. The aim of our study was to evaluate the clinical significance of survivin expression in advanced stages ovarian cancer with respect to the TP53 status.

Methods

Survivin and TP53 expression was evaluated immunohistochemically in 435 archival samples of ovarian carcinomas (244 patients were treated with platinum/cyclophosphamide-PC/PAC; 191-with taxane-platinum (TP) agents). Univariate and multivariate statistical analyses were performed in patients groups divided according to the administered chemotherapeutic regimen, and in subgroups with and without TP53 accumulation (TP53+ and TP53-, respectively).

Results

Nuclear and cytoplasmic survivin expression was observed in 92% and 74% of the carcinomas, respectively. In patients treated with TP, high nuclear survivin expression decreased the risk of disease recurrence and death, and increased the probability of high platinum sensitivity (p < 0.01), but only in the TP53(+) group, and not in the TP53(-) group.

Conclusions

It appears that TP53 status determines the clinical importance of nuclear survivin expression in taxane-platinum treated ovarian cancer patients.

VPA inhibits breast cancer cell migration by specifically targeting HDAC2 and down-regulating Survivin

Cell migration plays major roles in human breast cancer-related death, but the molecular mechanisms remain unclear. Valproic acid (VPA) is a broad-spectrum inhibitor of class I and II histone deacetylases and shows great anticancer activity in a variety of human cancers including breast cancer. In this study, we found that VPA significantly inhibited cell migration but not proliferation of human breast cancer MDA-MB-231 cells. Mechanistic studies found that VPA significantly inhibited the expression of Survivin. Knockdown of Survivin could obviously inhibited cell migration, while over-expression of Survivin markedly rescued the inhibition of VPA on cell migration. Further studies found that knockdown of HDAC2 completely mimicked the effects of VPA on Survivin and cell migration, and over-expression of Survivin could also rescue the effects of HDAC2 knockdown on cell migration. Collectively, these results indicated that HDAC2 may be the specific target of VPA in breast cancer cells, and specific inhibition of HDAC2, especially by small molecular chemicals may lead to less side-effects and provide a better strategy than VPA application for human breast cancer treatment.

The RNA-binding protein HuR stabilizes survivin mRNA in human oesophageal epithelial cells

Overexpression of survivin, a member of the IAP (inhibitor of apoptosis) family, has been correlated with poorer outcomes in multiple malignancies, including oesophageal cancer. The regulatory mechanisms, particularly at the post-transcriptional level, involved in survivin overexpression are not well understood. Previous work from our group has shown that the RNA-binding protein HuR (Hu antigen R), which is also overexpressed in several malignancies, stabilizes the mRNA of XIAP (X-linked IAP), another IAP family member. In the present study, we demonstrate the binding of HuR to a 288 bp fragment in the 3'-UTR (untranslated region) of survivin mRNA in human oesophageal epithelial cells. Unexpectedly, overexpression of HuR led to a decrease in survivin expression. This was associated with decreased survivin mRNA and promoter activity, suggesting a decrease in transcription. Levels of p53, a negative transcriptional regulator of survivin, increased following HuR overexpression, in conjunction with enhanced p53 mRNA stability. Silencing p53 prior to HuR overexpression resulted in increased survivin protein and mRNA stability. These results demonstrate that, in the absence of p53, HuR overexpression results in increased survivin mRNA stability and protein expression. This provides an additional explanation for the increased survivin expression observed in oesophageal cancer cells that have lost p53.

Targeting survivin in cancer: the cell-signalling perspective

Survivin, a prominent anticancer target, is ubiquitously expressed in a plethora of cancers and the evolving complexity in functional regulation of survivin is yet to be deciphered. However, pertaining to the recent studies, therapeutic modulation of survivin is critically regulated by interaction with prominent cell-signalling pathways [HIF-1α, HSP90, PI3K/AKT, mTOR, ERK, tumour suppressor genes (p53, PTEN), oncogenes (Bcl-2, Ras)] and a wide range of growth factors (EGFR, VEGF, among others). In our article we discuss, in detail, an overview of the recent developments in the pharmacological modulation of survivin via cell-signalling paradigms and antisurvivin therapeutics, along with an outlook on therapeutic management of survivin in drug-resistant cancers.

Survivin expression and targeting in breast cancer

INTRODUCTION

Survivin a multifunctional protein that controls cell division, inhibition of apoptosis and promotion of angiogenesis. It is expressed in most human neoplasm, but is absent in normal and differentiated tissues. The purpose of this article is to overview the expression of survivin, effect of its expression in response to treatment, correlation with other markers and newer advancement in targeting survivin.

METHODS

A detailed search of Medline was carried out using the following search strategy: "((survivin) OR ((apoptosis) AND (inhibitor OR inhibitors))) AND ((breast) AND (neoplasm OR neoplasms OR tumor OR tumor OR cancer OR carcinoma))". Abstract of all articles thus identified were reviewed to identify the relevant studies, full articles of studies thus identified were then obtained and reviewed. All relevant data was extracted and tabulated.

RESULTS

Survivin expression by Immunohistochemistry was identified in 65.3% (55.2-90.0%) of the breast cancer patients among the identified studies while survivin mRNA by RT-PCR was identified in 93.6% (90-97%). Survivin expression has been reported to be associated with over expression of HER 2, vascular endothelial growth factor (VEGF), urokinase plasminogen activator (uPA)/PAI-1.

CONCLUSION

Survivin is over expressed in majority of breast cancers. The over expression of survivin is found to correlate with HER 2 and EGFR expression. Survivin expression has been found to confer resistance to chemotherapy and radiation. Targeting survivin in experimental models improves survival. More studies are needed on the role of survivin in multi drug resistance (MDR) in the presence of Pgp/uPA/PAI-1 and the impact of survivin over expression in triple negative breast cancer.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tithonia diversifolia and its main active component tagitinin C induce survivin inhibition and G2/M arrest in human malignant glioblastoma cells

We investigated the antitumour activity of Tithonia diversifolia (TD) on malignant glioblastoma cells. Our results suggested that tagitinin C was the main component in viability inhibition on malignant glioblastoma cells, and also accounted to be the most abundant component (>65%) in TD extract. Both TD extract and tagitinin C exhibited vigorous potential to produce in vitro viability inhibition, autophagic cell death and G2/M arrest. Furthermore, the activity of survivin, a critical resistant-factor in cancer therapy, could be downregulated significantly by TD extract and tagitinin C. These findings suggested that TD extract and tagitinin C were effective for treating malignant glioblastoma.

Isolation and characterization of DUSP11, a novel p53 target gene

p53 regulates the expression of genes involved in cell cycle control, apoptosis and DNA damage repair. Here we demonstrate that DUSP11 (dual specificity phosphatase 11), a member of the protein tyrosine phosphatase family that binds to RNA-RNP complexes and RNA splicing factors, is a p53 target gene. Consistent with this, the expression of DUSP11 is induced in a p53-dependent manner after treatment with DNA damaging agents. Chromatin immunoprecipitation analysis showed that p53 binds to 2 putative p53 DNA binding sites in the promoter region of DUSP11. Colony formation and proliferation assays demonstrated that the ectopic expression of wildtype, but not catalytical inactive, DUSP11 leads to growth arrest. Furthermore inhibition of DUSP11 expression by shRNA increases the proliferation of normal and DNA damaged cells in tissue culture. Finally we show that the splicing factor SAM68 (Src-associated protein in mitotic cells) binds to DUSP11 in vitro and in vivo. Taken together these results suggest that DUSP11 contributes to p53-dependent inhibition of cell proliferation and that it might be involved in regulating RNA splicing through SAM68.

Expression of major guidance receptors is differentially regulated in spinal commissural neurons transfated by mammalian Barh genes

During development, commissural neurons in the spinal cord project their axons across the ventral midline, floor plate, via multiple interactions among temporally controlled molecular guidance cues and receptors. The transcriptional regulation of commissural axon-associated receptors, however, is not well characterized. Spinal dorsal cells are transfated into commissural neurons by misexpression of Mbh1, a Bar-class homeobox gene. We examined the function of another Bar-class homeobox gene, Mbh2, and how Mbh1 and Mbh2 modulate expression of the receptors, leading to midline crossing of axons. Misexpression of Mbh1 and Mbh2 showed the same effects in the spinal cord. The competence of spinal dorsal cells to become commissural neurons was dependent on the embryonic stage, during which misexpression of the Mbh genes was able to activate guidance receptor genes such as Rig1 and Nrp2. Misexpression of Lhx2, which has been recently shown to be involved in Rig1 expression, activated Rig1 but not Nrp2, and was less effective in generating commissural neurons. Moreover, expression of Lhx2 was activated by and required the Mbh genes. These findings have revealed a transcriptional cascade, in which Lhx2-dependent and -independent pathways leading to expression of guidance receptors branch downstream of the Mbh genes.

Gene expression profile and response to trastuzumab-docetaxel-based treatment in breast carcinoma

Background:

Resistance to trastuzumab is often observed in women with human epidermal growth factor receptor 2 (HER2)-positive breast cancer and has been shown to involve multiple potential mechanisms. We examined the ability of microarray analyses to determine the potential markers of pathological complete response (pCR).

Methods:

We conducted an analysis of tumours from 38 patients with locally advanced HER2-positive breast cancer who had received trastuzumab combined with docetaxel. Quantitative reverse transcriptase (RT)–PCR was used to assess the expression of 30 key genes; microarray analyses were carried out on 25 tumours to identify a prognostic gene expression profile, with 13 blinded samples used to validate the identified profile.

Results:

No gene was found to correlate with response by RT–PCR. The microarray analysis identified a gene expression profile of 28 genes, with 12 upregulated in the pCR group and 16 upregulated in non-pCR. The leave-one-out cross-validation test exhibited 72% accuracy, 86% specificity, and 55% sensitivity. The 28-gene expression profile classified the 13 validation samples with 92% accuracy, 89% specificity, and 100% sensitivity.

Conclusion:

Our results suggest that genes not involved in classical cancer pathways such as apoptosis or DNA repair could be involved in responses to a trastuzumab–docetaxel-based regimen. They also describe for the first time a gene expression signature that predicts trastuzumab response.

Survivin expression in esophageal cancer: correlation with p53 mutations and promoter polymorphism

Survivin is an inhibitor of apoptosis protein, which is selectively up-regulated in various cancers including esophageal cancer. The underlying mechanism of survivin overexpression in cancers is still unclear. We investigated resected tumor specimens from 100 esophageal cancer patients. Reverse transcription polymerase chain reaction was performed to evaluate survivin gene expression. Polymerase chain reaction-single strand conformation polymorphism was performed to investigate mutations of p53. We found that the survivin expression in tumors with mutant p53 is higher than that in tumors with wild type p53. Furthermore, the distribution of three polymorphisms in survivin promoter region in esophageal cancer patients was studied. The result indicated that the survivin expression was caused by a C allele in the survivin promoter polymorphism -625G/C in some degree. The methylation profile of survivin exon1 was also evaluated using bisulfite sequencing PCR. Our result indicated that survivin mRNA overexpression in cancer was not caused by its dysmethylation status. Therefore, our results suggested that the survivin expression depended on the p53 status and the C allele in the survivin promoter polymorphism -625G/C might increase the possibility of the survivin overexpression in esophageal cancer patients.

Influence of SiRNA Targeting Survivin on Chemosensitivity of H460/cDDP Lung Cancer Cells

We investigated the difference in survivin expression between a multidrug-resistant lung cancer cell line (H460/cDDP) and its parental counterpart (H460) and the influence of siRNA targeting survivin on the chemosensitivity of H460/cDDP. SiRNA targeting survivin was transfected into H460/cDDP cells using a liposome approach. Survivin mRNA and protein expression were significantly higher in H460/cDDP than H460 cells. The median inhibitory concentrations (IC50s) for cisplatin and paclitaxol in vitro against H460/cDDP cells were significantly lower in cells treated with survivin-specific siRNA than in control cells. Apoptosis and cleaved caspase-3 expression were analysed using annexin V and Western blotting, respectively, and showed a significant increase in apoptosis after treatment with the chemotherapeutic agents plus specific siRNA. Specific siRNA sensitized H460/cDDP cells to both cisplatin and paclitaxol. Thus, survivin appears to participate in the multidrug resistance mechanism of H460/cDDP cells and siRNA targeting survivin has the potential to increase the sensitivity of drug-resistant cancer cells to anticancer drugs.

Clinical and immunological evaluation of anti-apoptosis protein, survivin-derived peptide vaccine in phase I clinical study for patients with advanced or recurrent breast cancer

BACKGROUND

We previously reported that survivin-2B, a splicing variant of survivin, was expressed in various types of tumors and that survivin-2B peptide might serve as a potent immunogenic cancer vaccine. The objective of this study was to examine the toxicity of and to clinically and immunologically evaluate survivin-2B peptide in a phase I clinical study for patients with advanced or recurrent breast cancer.

METHODS

We set up two protocols. In the first protocol, 10 patients were vaccinated with escalating doses (0.1-1.0 mg) of survivin-2B peptide alone 4 times every 2 weeks. In the second protocol, 4 patients were vaccinated with the peptide at a dose of 1.0 mg mixed with IFA 4 times every 2 weeks.

RESULTS

In the first protocol, no adverse events were observed during or after vaccination. In the second protocol, two patients had induration at the injection site. One patient had general malaise (grade 1), and another had general malaise (grade 1) and fever (grade 1). Peptide vaccination was well tolerated in all patients. In the first protocol, tumor marker levels increased in 8 patients, slightly decreased in 1 patient and were within the normal range during this clinical trial in 1 patient. With regard to tumor size, two patients were considered to have stable disease (SD). Immunologically, in 3 of the 10 patients (30%), an increase of the peptide-specific CTL frequency was detected. In the second protocol, an increase of the peptide-specific CTL frequency was detected in all 4 patients (100%), although there were no significant beneficial clinical responses. ELISPOT assay showed peptide-specific IFN-gamma responses in 2 patients in whom the peptide-specific CTL frequency in tetramer staining also was increased in both protocols.

CONCLUSION

This phase I clinical study revealed that survivin-2B peptide vaccination was well tolerated. The vaccination with survivin-2B peptide mixed with IFA increased the frequency of peptide-specific CTL more effectively than vaccination with the peptide alone, although neither vaccination could induce efficient clinical responses. Considering the above, the addition of another effectual adjuvant such as a cytokine, heat shock protein, etc. to the vaccination with survivin-2B peptide mixed with IFA might induce improved immunological and clinical responses.

The expression of BIRC5 is correlated with loss of specific chromosomal regions in breast carcinomas

Expression of BIRC5 (survivin), a member of the inhibitor of apoptosis protein (IAP) family, is elevated in fetal tissues and in various human cancers. Mechanisms up-regulating BIRC5 in cancer are poorly understood. Here, we show that overexpression of BIRC5 induces a high proliferation level in MCF-7 breast tumor cells. In a population of 191 breast carcinomas, BIRC5 expression is not affected by BIRC5 promoter polymorphism at -31, or BIRC5 gene copy number. However, a significant correlation was found between expression of demethylase (dMTase) and expression of BIRC5. In addition, among 13 chromosomal regions tested for allelic loss [loss of heterozygosity (LOH)], two regions close to D3S1478 and D6S264 were related to BIRC5 expression. In tumors with LOH at D3S1478 and/or D6S264, BIRC5 expression was significantly increased. These regions have been suggested to harbor tumor suppressor genes and/or common fragile sites that may play a role in increasing genetic instability. These results suggest that genes located near D3S1478 and D6S264 might work by inhibiting, directly or indirectly, BIRC5 expression and thus their loss leads to its up-regulation. In addition, BIRC5 expression may induce breast tumor proliferation by promoting genetic instability. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Evidence of the modulation of mRNA splicing fidelity in humans by oxidative stress and p53

The majority of human genes generate mRNA splice variants and while there is little doubt that alternative splicing is an important biological phenomenon, it has also become apparent that some splice variants are associated with disease. To elucidate the molecular mechanisms responsible for generating aberrant splice variants, we have investigated alternative splicing of the human genes HPRT and POLB following oxidative stress in different genetic backgrounds. Our study revealed that splicing fidelity is sensitive to oxidative stress. Following treatment of cells with H2O2, the overall frequency of aberrant, unproductive splice variants increased in both loci. At least in POLB, splicing fidelity is p53 dependent. In the absence of p53, the frequency of POLB splice variants is elevated but oxidative stress does not further increase the frequency of splice variants. Our data indicate that mis-splicing following oxidative stress represents a novel and significant genotoxic outcome and that it is not simply DNA lesions induced by oxidative stress that lead to mis-splicing but changes in the alternative splicing machinery itself.