Survivin enhances telomerase activity via up-regulation of specificity protein 1- and c-Myc-mediated human telomerase reverse transcriptase gene transcription

The Relevance of Telomerase and Telomere-Associated Proteins in B-Acute Lymphoblastic Leukemia

Telomeres and telomerase are closely linked to uncontrolled cellular proliferation, immortalization and carcinogenesis. Telomerase has been largely studied in the context of cancer, including leukemias. Deregulation of human telomerase gene hTERT is a well-established step in leukemia development. B-acute lymphoblastic leukemia (B-ALL) recovery rates exceed 90% in children; however, the relapse rate is around 20% among treated patients, and 10% of these are still incurable. This review highlights the biological and clinical relevance of telomerase for B-ALL and the implications of its canonical and non-canonical action on signaling pathways in the context of disease and treatment. The physiological role of telomerase in lymphocytes makes the study of its biomarker potential a great challenge. Nevertheless, many works have demonstrated that high telomerase activity or hTERT expression, as well as short telomeres, correlate with poor prognosis in B-ALL. Telomerase and related proteins have been proven to be promising pharmacological targets. Likewise, combined therapy with telomerase inhibitors may turn out to be an alternative strategy for B-ALL.

A RUNX1/ETO-SKP2-CDKN1B axis regulates expression of telomerase in t (8;21) acute myeloid leukemia

The fusion oncoprotein RUNX1/ETO which results from the chromosomal translocation t (8;21) in acute myeloid leukemia (AML) is an essential driver of leukemic maintenance. We have previously shown that RUNX1/ETO knockdown impairs expression of the protein component of telomerase, TERT. However, the underlying molecular mechanism of how RUNX1/ETO controls TERT expression has not been fully elucidated. Here we show that RUNX1/ETO binds to an intergenic region 18 kb upstream of the TERT transcriptional start site and to a site located in intron 6 of TERT. Loss of RUNX1/ETO binding precedes inhibition of TERT expression. Repression of TERT expression is also dependent on the destabilization of the E3 ubiquitin ligase SKP2 and the resultant accumulation of the cell cycle inhibitor CDKN1B, that are both associated with RUNX1/ETO knockdown. Increased CDKN1B protein levels ultimately diminished TERT transcription with E2F1/Rb involvement. Collectively, our results show that RUNX1/ETO controls TERT expression directly by binding to its locus and indirectly via a SKP2-CDKN1B-E2F1/Rb axis.

Simultaneous Imaging and Visualizing the Association of Survivin mRNA and Telomerase in Living Cells by Using a Dual-Color Encoded DNA Nanomachine

Simultaneous imaging and especially visualizing the association of survivin mRNA and telomerase in living cells are of great value for the diagnosis and prognosis of cancer because their co-expression facilitates the development of cancer and identifies patients at high risk of tumor-related death. The challenge is to develop methods that enable visualizing the association of multiplex targets and avoid the distorted signals due to the different delivery efficiency of probes. Herein, we engineered a DNA triangular prism nanomachine (DTPN) for simultaneous multicolor imaging of survivin mRNA and telomerase and visualizing their association in living cells. Two recognizing probes targeted survivin mRNA and telomerase, and the reporter probe was assembled on the DTP in equal amounts, ensuring the same delivery efficiency of the probes to the living cells. The results showed that this DTPN could quantify intracellular survivin mRNA expression and telomerase activity. Moreover, it also enabled us to visualize the effect of the down-regulation of one target on the expression of another target under different drug stimulations. The results implied that our DTPN provided a promising platform for cancer diagnosis, prognosis, drug screening, and related biological research.

Mechanism of Human Telomerase Reverse Transcriptase (hTERT) Regulation and Clinical Impacts in Leukemia

The proliferative capacity and continuous survival of cells are highly dependent on telomerase expression and the maintenance of telomere length. For this reason, elevated expression of telomerase has been identified in virtually all cancers, including leukemias; however, it should be noted that expression of telomerase is sometimes observed later in malignant development. This time point of activation is highly dependent on the type of leukemia and its causative factors. Many recent studies in this field have contributed to the elucidation of the mechanisms by which the various forms of leukemias increase telomerase activity. These include the dysregulation of telomerase reverse transcriptase (TERT) at various levels which include transcriptional, post-transcriptional, and post-translational stages. The pathways and biological molecules involved in these processes are also being deciphered with the advent of enabling technologies such as next-generation sequencing (NGS), ribonucleic acid sequencing (RNA-Seq), liquid chromatography-mass spectrometry (LCMS/MS), and many others. It has also been established that TERT possess diagnostic value as most adult cells do not express high levels of telomerase. Indeed, studies have shown that prognosis is not favorable in patients who have leukemias expressing high levels of telomerase. Recent research has indicated that targeting of this gene is able to control the survival of malignant cells and therefore offers a potential treatment for TERT-dependent leukemias. Here we review the mechanisms of hTERT regulation and deliberate their association in malignant states of leukemic cells. Further, we also cover the clinical implications of this gene including its use in diagnostic, prognostic, and therapeutic discoveries.

The Multiple Roles of the IAP Super-family in cancer

The Inhibitor of Apoptosis proteins (IAPs) are a family of proteins that are mainly known for their anti-apoptotic activity and ability to directly bind and inhibit caspases. Recent research has however revealed that they have extensive roles in governing numerous other cellular processes. IAPs are known to modulate ubiquitin (Ub)-dependent signaling pathways through their E3 ligase activity and influence activation of nuclear factor κB (NF-κB). In this review, we discuss the involvement of IAPs in individual hallmarks of cancer and the current status of therapies targeting these critical proteins.

Screening and Identification of Molecular Targets Involved in Preventing Gastric Precancerous Lesions in Chronic Atrophic Gastritis by Qilianshupi Decoction

Chronic atrophic gastritis (CAG) is a common and possibly precancerous digestive tract disease. Development of drugs with effect of preventing precancerous lesions draws the eyes of global researchers. Qilianshupi decoction (QLSP) is a Traditional Chinese Medicine (TCM) that is commonly used to treat CAG, but few studies have explored the mechanism of QLSP on treating CAG. This study investigated the molecular targets of the component herbs of QLSP in preventing precancerous lesions based on network pharmacology. Network pharmacology analysis revealed that the 6 herbs regulated multiple CAG-related genes, among which the most important were cancer-related pathway (apoptosis, p53, and VEGF) and epithelial cell signaling in Helicobacter pylori infection. Further animal experiments showed that the expression of survivin and p53 in precancerous lesions of CAG rats was significantly increased which was suppressed by QLSP. Moreover, telomerase activity was inhibited in precancerous lesions of CAG rats, and telomere length of gastric mucosa was increased, which was reversed by QLSP. Our results suggest that the components of QLSP prevents gastric precancerous lesions through decreasing the expression of survivin and p53 and regulating telomerase activity and telomere length in CAG.

Expression of pluripotency-related genes is highly dependent on trichostatin A-assisted epigenomic modulation of porcine mesenchymal stem cells analysed for apoptosis and subsequently used for generating cloned embryos

The present study sought to examine whether trichostatin A (TSA)-assisted epigenetic transformation of porcine bone marrow (BM)-derived mesenchymal stem cells (BM-MSCs) affects the transcriptional activities of pluripotency-related genes (Oct4, Nanog, c-Myc, Sox2 and Rex1), multipotent stemness-related gene (Nestin) and anti-apoptotic/anti-senescence-related gene (Survivin). Epigenetically transformed or non-transformed BM-MSCs that had been transcriptionally profiled by qRT-PCR and had been analysed for different stages of apoptosis progression provided a source of nuclear donor cells for the in vitro production of cloned pig embryos. TSA-mediated epigenomic modulation has been found to enhance the multipotency extent, stemness and intracellular anti-ageing properties of porcine BM-MSCs. This has been confirmed by the relative abundances for Nanog, c-Myc Rex1, Sox2 and Survivin mRNAs in TSA-exposed BM-MSCs that turned out to be significantly higher than those of TSA-unexposed BM-MSCs. Additionally, TSA-assisted epigenomic modulation of BM-MSCs did not impact the caspase-8 activity, Bax protein expression and the incidence of TUNEL-positive cells. In conclusion, the considerably elevated quantitative profiles of Sox2, Rex1, c-Myc, Nanog and Survivin mRNA transcripts seem to trigger improved reprogrammability of TSA-treated BM-MSC nuclei in cloned pig embryos that thereby displayed remarkably increased blastocyst formation rates as compared to those noticed for embryos derived from TSA-untreated BM-MSCs.

Down regulation of human telomerase reverse transcriptase (hTERT) expression by BIBR1532 in human glioblastoma LN18 cells

Increased telomerase activity can be blocked by targeting the hTERT activity at both RNA and catalytic subunits. Various inhibitors had been used to regulate hTERT activity in glioblastoma cell lines and showed promising results. The present study hypothesized that the telomerase specific inhibitor BIBR1532 can effectively down-regulate the telomerase activity in LN18 glioblastoma cell line. LN18 glioblastoma cell line was treated with various concentrations of BIBR1532 at different time intervals. MTT assay was performed to determine cell viability after BIBR1532 treatment. hTERT mRNA and protein expression were determined by qRT-PCR and western blotting, respectively. Flow cytometry and TRAP assay was performed to detect the rate of apoptosis and telomerase activity in treated and control samples. One-way ANOVA was performed to compare the mean values of variables in control and BIBR1532 treated groups. LN18 cells showed a significant dose dependent cytotoxic effect after treatment with BIBR1532. hTERT mRNA expression in cells treated with 25, 100 and 200 μM BIBR1532 treated groups was decreased ~ 21, ~ 61.2, and ~ 77%, respectively (p < 0.05). We also observed that, BIBR1532 treatment reduced the expression of hTERT protein in LN18 cells in a dose dependent manner. The Flow cytometry data showed that, the drug induced significant increase in the total percentage of apoptotic cells with 200 μM concentration of BIBR1532 at all time points. BIBR1532 exhibited potent inhibition of telomerase activity in a dose-dependent manner in LN18 cells. BIBR1532 could induce apoptosis in LN18 cells through the downregulation of telomerase activity at transcriptional and translational level. We conclude that BIBR1532 may be a therapeutic agent to suppress telomerase activity, however, further efforts are necessary in order to explore this therapeutic strategy.

Leukocyte Telomere Length and Pancreatic Cancer Risk: Updated Epidemiologic Review

Many risk factors have been firmly established for pancreatic cancer (PC), but the molecular processes by which known risk factors influence susceptibility to PC are not clear. There has been a recent upsurge of interest in the role of telomere length (TL), the protective DNA sequence repeats at chromosome ends, in pancreatic carcinogenesis. Given this heightened interest, we performed an in-depth, focused, and up-to-date review of the epidemiological evidence linking leukocyte TL (LTL) with PC risk. We searched MEDLINE, Embase, and the Cochrane Library databases for all published studies on LTL and PC risk, up to May 2017. Five studies were identified for review: 4 nested case-control studies and 1 retrospective case-control study. Two studies found opposite associations between LTL and PC risk: 1 found a dose-response positive association and the other found a dose-response inverse association. Two studies also found a "U-shaped" association, whereas another reported a weak nonlinear relationship. We offer potential reasons for the conflicting findings including variation in study design, biospecimen characteristics, and differences in interlaboratory measurements of TL. Future studies should carefully control for risk factors of PC that are associated also with telomere attrition and investigate the role of genetic variation in TL maintenance.

Establishment of a novel human lymphoblastic cell strain with the long arm of chromosome 11 aberration without MLL rearrangement

At present, all cell strains derived from acute lymphoblastic leukemia (ALL) patients with the long arm of chromosome 11 aberration are accompanied with mixed lineage leukemia (MLL) gene rearrangement. In this study, we established a permanent ALL cell strain CHH-1 with the long arm of chromosome 11 aberration and without MLL rearrangement, hoping that it could be used for the research of ALL with such genetic abnormality. CHH-1 cell strain was certified through morphology, immunophenotype, genetics and immunoglobulin (Ig) gene rearrangement analysis. Cell characteristics including tumorigenic ability, semisolid colony forming ability, telomerase activity, autocrine and invasion were further detected. Cells were with an add(11)(q23) structural abnormality without MLL rearrangement, and were consistent with the genetic abnormality of the patient. In addition, these cells had features of tumor-forming ability, high colony forming capacity, unique cytokine autocrine mode, high telomerase activity, and high invasion ability. CHH-1 may prove to be a useful cell model for the research of human leukemia with genetic aberration in chromosome 11, and help explore the role of such genetic abnormality in the pathogenesis, progression and prognosis of ALL, and in developing new target drugs.

In vitro evaluation of ruthenium complexes for photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) is a promising anti-tumor treatment strategy. Photosensitizer is one of the most important components of PDT. In this work, the anticancer activities of PDT mediated by six new ruthenium porphyrin complexes were screened. The mechanisms of the most efficacious candidate were investigated.

METHODS

Photocytotoxicity of the six porphyrins was tested. The most promising complex, Rup-03, was further investigated using Geimsa staining, which indirectly detects reactive oxygen species (ROS) and subcellular localization. Mitochondrial membrane potential (MMP), cell apoptosis, DNA fragmentation, c-Myc gene expression, and telomerase activities were also assayed.

RESULTS

Rup-03 and Rup-04 had the lowest IC₅₀ values. Rup-03 had an IC₅₀ value of 29.5±2.3μM in HepG2 cells and 59.0±6.1μM in RAW264.7 cells, while Rup-04 had an IC₅₀ value of 40.0±3.8μM in SGC-7901 cells. The complexes also induced cellular morphological changes and impaired cellular ability to scavenge ROS, and accumulated preferentially in mitochondria and endoplasmic reticulum. Rup-03 reduced MMP levels, induced apoptosis, and repressed both c-Myc mRNA expression and telomerase activity in HepG2 cells.

CONCLUSIONS

Among six candidates, Rup-03-mediated PDT is most effective against HepG2 and RAW264.7, with a similar efficacy as that of Rup-04-mediated PDT against SGC-7901 cells. Repression of ROS scavenging activities and c-Myc expression, which mediated DNA damage-induced cell apoptosis and repression of telomerase activity, respectively, were found to be involved in the anticancer mechanisms of Rup-03.

Transcription Regulation of the Human Telomerase Reverse Transcriptase (hTERT) Gene

Embryonic stem cells and induced pluripotent stem cells have the ability to maintain their telomere length via expression of an enzymatic complex called telomerase. Similarly, more than 85%–90% of cancer cells are found to upregulate the expression of telomerase, conferring them with the potential to proliferate indefinitely. Telomerase Reverse Transcriptase (TERT), the catalytic subunit of telomerase holoenzyme, is the rate-limiting factor in reconstituting telomerase activity in vivo. To date, the expression and function of the human Telomerase Reverse Transcriptase (hTERT) gene are known to be regulated at various molecular levels (including genetic, mRNA, protein and subcellular localization) by a number of diverse factors. Among these means of regulation, transcription modulation is the most important, as evident in its tight regulation in cancer cell survival as well as pluripotent stem cell maintenance and differentiation. Here, we discuss how hTERT gene transcription is regulated, mainly focusing on the contribution of trans-acting factors such as transcription factors and epigenetic modifiers, as well as genetic alterations in hTERT proximal promoter.

Influence of a survivin suppressor YM155 on the chemoresistance of canine histiocytic sarcoma cells

Histiocytic sarcoma (HS) in dogs exhibits aggressive biological behaviors and currently few effective treatments are available. Survivin could serve as a potential therapeutic target in several cancers. Sepantronium bromide (YM155) is a potential novel survivin-targeting agent and in this study the influence of survivin expression on clinical outcomes and the effects of YM155 on biological activities in HS cells were investigated. Specimens of HS dogs (n = 30) and four canine HS cell lines were used. The correlation between survivin expression and clinical outcome in the HS dogs was retrospectively assessed using quantitative PCR. Following YM155 treatment of cell lines, apoptosis, cell viability, and drug transporter activities were evaluated using annexin V staining, methylthiazole tetrazolium assays, and Hoechst-33342 staining, respectively. Elevated survivin expression in the HS dogs corresponded with reduced disease-free intervals and survival time, and increased chemoresistance, which led to poor clinical outcomes. Furthermore, YM155 treatment suppressed cell-growth and resistance to lomustine in HS cells by inhibiting the activity of ATP-binding cassette transporters. The evidence presented here supports favorable preclinical evaluation and indicates that survivin-targeted therapies might be effective against HS dogs.

Survivin suppressor (YM155) enhances chemotherapeutic efficacy against canine histiocytic sarcoma in murine transplantation models

Histiocytic sarcoma (HS) in dogs exhibits aggressive clinical and biological behavior. Currently, no effective treatments are available for dogs with HS. Survivin, a member of a family of apoptosis protein inhibitors, could serve as a potential therapeutic target in several canine cancers. Sepantronium bromide (YM155) has recently been established as a novel survivin-targeting agent. The aim of this study was to use YM155 as a tool for evaluating survivin-targeted therapies against dogs with HS, and to investigate how YM155 treatment affects antitumor and chemotherapeutic efficacies in murine xenograft models using canine HS cells. The results showed that in HS cells with lomustine (CCNU) resistance, YM155 treatment suppressed both the cell-growth potential and cell resistance to CCNU, which essentially increases the chemotherapy efficacy in the murine models. The evidence presented here supports the favorable preclinical evaluation that survivin-targeted therapies might be effective against HS in dogs.

Diagnostic relevance of autoantibody detection against inhibitors of apoptosis proteins in colon cancer and colon adenoma

Autoantibodies against cancer-related antigens may be detected in the sera of patients with various types of cancer, although their clinical utility has not yet been established. In this study, we aimed to demonstrate the diagnostic relevance of autoantibody detection against inhibitor of apoptosis protein (IAP) family members in colon cancer, as compared to anti-p53 antibody, carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9. We established an ELISA system using original recombinant proteins of IAP family members (survivin, livin and X-linked IAP) and measured the expression levels in the sera of 62 healthy donors, 250 patients with colon polyps (adenoma) and 176 patients with colon cancer. When the cutoff value was set as the mean value + 2 standard deviations in healthy donors, anti-survivin exhibited the highest positivity rate (24.4%) among IAP autoantibodies in cancer patients. Furthermore, the anti-survivin antibody exhibited a high positivity rate in early-stage carcinoma and adenoma. In the combination assay, reflecting the significantly high positivity rate of CEA in stage IV tumors, the positivity rate was highest when combining the detection of anti-survivin antibody and CEA in cancer patients (50.0%), indicating that this combination may not be useful for the diagnosis of early-stage cancers. By contrast, reflecting the complete independencE of anti-survivin and anti-p53 antibodies, the combination of detecting these two antibodies resulted in the highest positivity rate (35.6%) in early-stage disease (stage 0-I). These results suggest that the combined measurement of anti-survivin and anti-p53 antibodies may be useful for the detection of early-stage colon cancer.

Sp1 and the 'hallmarks of cancer'

For many years, transcription factor Sp1 was viewed as a basal transcription factor and relegated to a role in the regulation of so-called housekeeping genes. Identification of Sp1's role in recruiting the general transcription machinery in the absence of a TATA box increased its importance in gene regulation, particularly in light of recent estimates that the majority of mammalian genes lack a TATA box. In this review, we briefly consider the history of Sp1, the founding member of the Sp family of transcription factors. We review the evidence suggesting that Sp1 is highly regulated by post-translational modifications that positively and negatively affect the activity of Sp1 on a wide array of genes. Sp1 is over-expressed in many cancers and is associated with poor prognosis. Targeting Sp1 in cancer treatment has been suggested; however, our review of the literature on the role of Sp1 in the regulation of genes that contribute to the 'hallmarks of cancer' illustrates the extreme complexity of Sp1 functions. Sp1 both activates and suppresses the expression of a number of essential oncogenes and tumor suppressors, as well as genes involved in essential cellular functions, including proliferation, differentiation, the DNA damage response, apoptosis, senescence and angiogenesis. Sp1 is also implicated in inflammation and genomic instability, as well as epigenetic silencing. Given the apparently opposing effects of Sp1, a more complete understanding of the function of Sp1 in cancer is required to validate its potential as a therapeutic target.

AMPK/mTOR-mediated inhibition of survivin partly contributes to metformin-induced apoptosis in human gastric cancer cell

Recent studies demonstrated that metformin exerts anti-neoplastic effect in a spectrum of malignancies. However, the mechanism whereby metformin affects various cancers, including gastric cancer, is poorly elucidated. Considering apoptosis plays critical role in tumorigenesis, we, in the present study, investigated the in vitro apoptotic effect of metformin on human gastric cancer cell and the underlying mechanism. Three differently-differentiated gastric cancer cell lines, MKN-28, SGC-7901 and BGC-823, along with one noncancerous gastric cell line GES-1 were used. We found that metformin treatment selectively induces apoptosis in the 3 cancer cell lines, but not the noncancerous one, as confirmed by flow cytometry, Caspase-Glo assay and western blotting against PARP and cleaved caspase 3. Moreover, the apoptotic effect of metformin seems to correlate negatively with the differentiation degree of gastric cancer. Metformin-induced apoptosis may be partially mediated through inhibition of anti-apoptotic survivin. Additionally, AMPK and mTOR, 2 important regulatory molecules responsible for metformin action, were investigated for their possible involvements in metformin-induced apoptosis of gastric cancer cell. AMPK knockdown by siRNA restores metformin-inhibited survivin expression and partially abolishes metformin-induced apoptosis. Similarly, forced overexpression of mTOR downstream effector p70S6K1 relieves metformin-induced inhibition of survivin and partly attenuates metformin-induced apoptosis. More importantly, survivin overexpression alleviates metformin-induced apoptosis. Xenograft nude mouse experiment also confirmed that AMPK/mTOR-mediated decrease of suvivin is in vivo implicated in metformin-induced apoptosis. Taken together, these evidences suggest that AMPK/mTOR-mediated inhibition of survivin may partly contribute to metformin-induced apoptosis of gastric cancer cell.

Survivin inhibition via EZN-3042 in canine lymphoma and osteosarcoma

Canine lymphoma (LSA) and osteosarcoma (OS) have high mortality rates and remain in need of more effective therapeutic approaches. Survivin, an inhibitor of apoptosis (IAP) family member protein that inhibits apoptosis and drives cell proliferation, is commonly elevated in human and canine cancer. Survivin expression is a negative prognostic factor in dogs with LSA and OS, and canine LSA and OS cell lines express high levels of survivin. In this study, we demonstrate that survivin downregulation in canine LSA and OS cells using a clinically applicable locked nucleic acid antisense oligonucleotide (EZN-3042, Enzon Pharmaceuticals, Piscataway Township, NJ, USA) inhibits growth, induces apoptosis and enhances chemosensitivity in vitro, and inhibits survivin transcription and protein production in orthotopic canine OS xenografts. Our findings strongly suggest that survivin-directed therapies might be effective in treatment of canine LSA and OS and support evaluation of EZN-3042 in dogs with cancer.

Influence of survivin-targeted siRNA on the biological features of colorectal carcinoma cells

The transient transfection of survivin-targeted siRNA to Lovo cells and its influence on the biological features were studied. Two pairs of 19 base pairs (bp) siRNA-specific targeted survivin gene were designed and synthesized by in vitro transcription (Survivin-1, Survivin-2). After transient transfection of the two survivin-targeted siRNAs to Lovo cells by Lipofectamine™ 2000, the expression of survivin mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). Apoptosis was detected by flow cytometry and cell proliferation was evaluated by MTT assay. We found that the expression levels of survivin mRNA of the two RNAi groups (Survivin-1 group and Survivin-2 group) respectively decreased by 70% and 39.1% compared with the control Lovo's. Seventy-two hours after transfection, apoptosis rates of the two RNAi groups were 21.51% and 26.28%, both of which were higher than control Lovo's (9.03%). The results at 72 h after transfection were that the optical density (OD) at 490 nm of the two RNAi groups was 0.581 ± 0.070 and 0.681 ± 0.104, both of which were much lower than the control Lovo's (2.060 ± 0.272). Based on the results, we can draw a conclusion that the two survivin-targeted siRNAs successfully suppressed the expression of survivin mRNA, inhibited cell growth and induce cell apoptosis. It provides a powerful evidence for colorectal carcinoma gene therapy.

Inhibition of survivin influences the biological activities of canine histiocytic sarcoma cell lines

Canine histiocytic sarcoma (CHS) is an aggressive malignant neoplasm that originates from histiocytic lineage cells, including dendritic cells and macrophages, and is characterized by progressive local infiltration and a very high metastatic potential. Survivin is as an apoptotic inhibitory factor that has major functions in cell proliferation, including inhibition of apoptosis and regulation of cell division, and is expressed in most types of human and canine malignant neoplasms, including melanoma and osteosarcoma. To investigate whether survivin was expressed at high levels in CHS and whether its expression was correlated with the aggressive biological behavior of CHS, we assessed relation between survivin expression and CHS progression, as well as the effects of survivin inhibition on the biological activities of CHS cells. We comparatively analyzed the expression of 6 selected anti-apoptotic genes, including survivin, in specimens from 30 dogs with histiocytic sarcoma and performed annexin V staining to evaluate apoptosis, methylthiazole tetrazolium assays to assess cell viability and chemosensitivity, and latex bead assays to measure changes in phagocytic activities in 4 CHS cell lines and normal canine fibroblasts transfected with survivin siRNA. Survivin gene expression levels in 30 specimens were significantly higher than those of the other 6 genes. After transfection with survivin siRNA, apoptosis, cell growth inhibition, enhanced chemosensitivity, and weakened phagocytic activities were observed in all CHS cell lines. In contrast, normal canine fibroblasts were not significantly affected by survivin knockdown. These results suggested that survivin expression may mediate the aggressive biological activities of CHS and that survivin may be an effective therapeutic target for the treatment of CHS.

Expression of human telomerase reverse transcriptase in vulvar intraepithelial neoplasia and squamous cell carcinoma: an immunohistochemical study with survivin and p53

CONTEXT

Human telomerase reverse transcriptase (hTERT), an enzyme that enables cells to overcome replicative senescence and to divide indefinitely, is overexpressed in many cancers and their precursor lesions.

OBJECTIVE

To test whether hTERT expression is related to neoplastic progression and resistance to apoptosis in vulvar epithelia.

DESIGN

Immunoexpression of hTERT was evaluated in 101 formalin-fixed, paraffin-embedded archival vulvar epithelia consisting of normal squamous vulvar epithelia (n  =  25), lichen sclerosus (n  =  10), high-grade classic vulvar intraepithelial neoplasia (n  =  16), differentiated vulvar intraepithelial neoplasia (n  =  18), and vulvar invasive keratinizing squamous cell carcinoma (n  =  32) and related to survivin and p53 expression. Immunostaining for all factors was scored for moderate and strong intensities with regard to quantity to determine upregulation and overexpression (score 0, 0% immunoreactive cells; score 1+, <5% immunoreactive cells; score 2+, 5% to 50% immunoreactive cells; score 3+, >50% immunoreactive cells). Score 3+ was considered as overexpression.

RESULTS

Nuclear hTERT immunoexpression was closely related to survivin reactivity, increased from normal vulvar squamous epithelia to lichen sclerosus and to high-grade classic vulvar intraepithelial neoplasia, differentiated vulvar intraepithelial neoplasia, and invasive keratinizing squamous cell carcinoma (P < .001), and followed the morphologic distribution of atypical squamous epithelial cells. Overexpression of hTERT was comparable to that seen for p53 in invasive keratinizing squamous cell carcinoma (P  =  .62); significant differences were calculated for differentiated vulvar intraepithelial neoplasia (P  =  .003) and high-grade classic vulvar intraepithelial neoplasia (P  =  .001).

CONCLUSION

Human telomerase reverse transcriptase is upregulated in vulvar intraepithelial neoplasia and invasive keratinizing squamous cell carcinoma compared with nonneoplastic squamous epithelia of the vulva as an apparently early and preinvasive event in the neoplastic transformation, with development of cellular longevity and resistance to apoptosis by survivin activation as associated features, independent of the etiology of vulvar intraepithelial neoplasia.

Discovery of survivin inhibitors and beyond: FL118 as a proof of concept

Survivin, a novel antiapoptotic protein molecule, plays a central role in cancer cell survival/proliferation networks and has therefore become a therapeutic target for cancer drug discovery efforts. There are two strategies for discovering survivin inhibitors. One is based on survivin interactions within the cell and the other strategy is based on blocking survivin expression. Survivin inhibitors developed by the first strategy would disrupt a particular survivin function. These survivin inhibitors could also be useful tools for delineating the mechanism of action of survivin. The second strategy may use a reporter system of the survivin gene to screen drug libraries. To date, two molecules, YM155 and FL118, have been identified using this strategy. These two examples provide a proof of concept that screens for inhibitors of survivin expression using survivin gene reporter assays as surrogate markers will uncover versatile small molecules that not only inhibit survivin but also inhibit other essential cancer survival/proliferation-associated targets and/or signaling pathways. This review provides an overview of current information in the area relevant to survivin inhibitors that may facilitate future studies.

Expression and function of survivin in canine osteosarcoma

Osteosarcoma has a high mortality rate and remains in need of more effective therapeutic approaches. Survivin is an inhibitor of apoptosis family member protein that blocks apoptosis and drives proliferation in human cancer cells where it is commonly elevated. In this study, we illustrate the superiority of a canine osteosarcoma model as a translational tool for evaluating survivin-directed therapies, owing to the striking similarities in gross and microscopic appearance, biologic behavior, gene expression, and signaling pathway alterations. Elevated survivin expression in primary canine osteosarcoma tissue correlated with increased histologic grade and mitotic index and a decreased disease-free interval (DFI). Survivin attenuation in canine osteosarcoma cells inhibited cell-cycle progression, increased apoptosis, mitotic arrest, and chemosensitivity, and cooperated with chemotherapy to significantly improve in vivo tumor control. Our findings illustrate the utility of a canine system to more accurately model human osteosarcoma and strongly suggest that survivin-directed therapies might be highly effective in its treatment.

Survivin and telomerase expression in the uterine cervix of women with human papillomavirus-induced lesions

INTRODUCTION

Infection by human papillomavirus is the most important risk factor in the pathogenesis of uterine cervical cancer. The aims of this study were to evaluate the expression of survivin protein and telomerase enzyme in samples of uterine cervix from women with human papillomavirus-induced lesions and to determine the relationship between survivin and telomerase expression and the different grades of cervical squamous intraepithelial neoplasia and invasive cervical carcinoma.

METHODS

Biopsy samples from the uterine cervix of 105 women aged 18 to 80 years were analyzed. The patients were divided into 5 groups: WN group, 20 patients without neoplasia; CIN-1 group, 24 patients with grade 1 cervical intraepithelial neoplasia (CIN), grade 1; CIN-2 group, 20 patients with CIN grade 2; CIN-3 group, 24 patients with CIN, grade 3; and ICC group, 17 patients with invasive cervical carcinoma. Human papillomavirus detection, telomerase activity, and survivin expression were assessed using polymerase chain reaction (PCR), real-time PCR (RT-PCR), and immunochemistry, respectively.

RESULTS

There was a significant increase in the expression of telomerase and survivin associated with the severity of the lesion.

CONCLUSIONS

The results suggest that mechanisms that promote both cell proliferation (telomerase activity) and cell survival (survivin expression) are active in cervical cancer and its precursor lesions. There was a negative correlation between survivin expression and the number of PCR cycles necessary to detect telomerase activity in the total sample, achieving statistical significance in patients in the CIN-3 group.

Enhanced expression of proproliferative and antiapoptotic genes in ulcerative colitis-associated neoplasia

BACKGROUND

Inflammatory bowel diseases including long-standing ulcerative colitis (UC) have an increased risk of evolving into colorectal cancer (CRC). The overexpression of some proproliferative and antiapoptotic genes, such as survivin, telomerase catalytic subunit (hTERT), integrin-linked kinase (ILK), and regulatory factors c-MYB and Tcf-4, has been implicated in the development and progression of several human malignancies including CRC.

METHODS

In this study we analyzed the expression alterations of these markers and proinflammatory enzymes cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) during the transition of colonic mucosa from chronic inflammation to epithelial neoplasia in biopsies of UC patients using quantitative real-time polymerase chain reaction and immunohistochemistry; additionally, we compared the expression profiles of this gene panel in samples of patients with CRC after tumor resection and in human tumor xenografts of SW620 malignant colonic cells.

RESULTS

The transcript levels of survivin, c-MYB, COX-2, iNOS, and Tcf-4 showed a statistically significant increase during neoplastic transformation of UC patient colonic mucosa, whereas hTERT and ILK were not elevated. In contrast, the specimens of CRC showed upregulated expression of not only survivin, c-MYB, Tcf-4, COX-2, and iNOS but also hTERT. A similar expression profile was observed in human tumor xenografts in which all transcripts with the exception of c-MYB were upregulated.

CONCLUSIONS

These results suggest that telomerase and ILK activation occurs during the later stages of carcinoma progression, whereas upregulation of survivin, c-MYB, and Tcf-4 is a feature of the early stage of development of neoplasia, and thus, they might serve as early indicators for UC-associated colorectal carcinogenesis.

Telomerase regulation in hematological cancers: a matter of stemness?

Human telomerase is a nuclear ribonucleoprotein enzyme complex that catalyzes the synthesis and extension of telomeric DNA. This enzyme is highly expressed and active in most malignant tumors while it is usually not or transiently detectable in normal somatic cells, suggesting that it plays an important role in cellular immortalization and tumorigenesis. As most leukemic cells are generally telomerase-positive and have often shortened telomeres, our understanding of how telomerase is deregulated in these diseases could help to define novel therapies targeting the telomere/telomerase complex. Nonetheless, considering that normal hematopoietic stem cells and some of their progeny do express a functional telomerase, it is tempting to consider such an activity in leukemias as a sustained stemness feature and important to understand how telomere length and telomerase activity are regulated in the various forms of leukemias.

Prognostic relevance of hTERT mRNA expression in ductal adenocarcinoma of the pancreas

Telomerase is thought to play an essential role in tumorigenesis and progression. Its activity is directly correlated with the expression of its catalytic subunit, human telomerase reverse transcriptase (hTERT). A correlation of transcript expression with a poor prognosis has been detected in different human malignancies. However, data on hTERT in pancreatic ductal adenocarcinoma (PDAC) are purely descriptive so far. Therefore, we evaluated the impact of hTERT expression on patients' prognosis. Human telomerase reverse transcriptase mRNA isolates from 56 human microdissected PDAC tissues were analyzed by quantitative reverse transcription-polymerase chain reaction and multivariate Cox regression hazard test. Elevated hTERT transcript levels were measured in 23 of 56 PDAC tissues, 33 patients showed no detectable transcripts. Unexpectedly, a low expression of hTERT mRNA levels was associated with a worse prognosis for overall survival (relative risk = 5.33; P = .013) when compared to high levels, whereas undetectable expression showed an intermediate risk of tumor-related death. These data challenge previous findings outlining hTERT's negative impact on overall survival. The risk pattern obtained in PDAC suggests a more complex regulation of hTERT.

The PPARalpha/p16INK4a pathway inhibits vascular smooth muscle cell proliferation by repressing cell cycle-dependent telomerase activation

Peroxisome proliferator-activated receptor (PPAR)alpha, the molecular target for fibrates used to treat dyslipidemia, exerts pleiotropic effects on vascular cells. In vascular smooth muscle cells (VSMCs), we have previously demonstrated that PPARalpha activation suppresses G(1)-->S cell cycle progression by targeting the cyclin-dependent kinase inhibitor p16(INK4a) (p16). In the present study, we demonstrate that this inhibition of VSMC proliferation by PPARalpha is mediated through a p16-dependent suppression of telomerase activity, which has been implicated in key cellular functions including proliferation. PPARalpha activation inhibited mitogen-induced telomerase activity by repressing the catalytic subunit telomerase reverse transcriptase (TERT) through negative cross-talk with an E2F-1-dependent trans-activation of the TERT promoter. This trans-repression involved the recruitment of the retinoblastoma (RB) family proteins p107 and p130 to the TERT promoter resulting in impaired E2F-1 binding, an effect that was dependent on p16. The inhibition of cell proliferation by PPARalpha activation was lost in VSMCs following TERT overexpression or knockdown, pointing to a key role of telomerase as a target for the antiproliferative effects of PPARalpha. Finally, we demonstrate that PPARalpha agonists suppress telomerase activation during the proliferative response following vascular injury, indicating that these findings are applicable in vivo. In concert, these results demonstrate that the antiproliferative effects of PPARalpha in VSMCs depend on the suppression of telomerase activity by targeting the p16/RB/E2F transcriptional cascade.

Metachronous cancer development in patients with sporadic colorectal adenomas-multivariate risk model with independent and combined value of hTERT and survivin

BACKGROUND AND AIMS

Accurate, long-term risk predictors for colorectal cancer development in patients with sporadic adenomas are lacking. We sought to validate biomarkers predictive of metachronous colorectal cancer (mCRC) in patients with sporadic colorectal adenomas, using 374 consecutive patients from a large defined population.

MATERIALS AND METHODS

Risk evaluation was performed for patient and adenoma risk factors (morphometric longest nuclear axis and immunohistochemical markers survivin, human telomerase reverse transcriptase (hTERT), beta-catenin, p16INK4a, p21CIP1, and cyclin D1). Diagnostic accuracy was assessed by receiver-operating characteristics curve analysis, and uni- and multivariate survival analysis was performed.

RESULTS/FINDINGS

Of the 374 patients, 26 (7%) developed mCRC with a median of 5.6 years (range 2-19) from index adenoma. Independent risk factors included age greater than or equal to 60 years, proximal location, multiplicity (greater than or equal to three adenomas), and high-grade neoplasia, with high-grade intraepithelial neoplasia and proximal location as the strongest on multivariate analysis (hazard ratio [HR] of 4.1 and 5.2, respectively; both p< 0.05). The molecular markers hTERT (HR 11.3, 95% confidence interval [CI] 3.9-33.1; p < 0.001) and survivin (HR 7.0, 95% CI 2.4-20.5; p < 0.001) were independent predictors for mCRC, and proximal location (4 of 16 = 25% with mCRC) was the only clinical one. The value of hTERT and survivin were retained in the validation set. Survivin and hTERT together yielded high mCRC risk when both were positive (15 of 51 = 29%; HR 14.3, 5.6-36.5), modest with one positive (survivin 4 of 90 = 4.4%; hTERT 4 of 60 = 6.7%), and no risk with both negative (0 of 144 = 0%).

INTERPRETATION/CONCLUSION

hTERT and survivin are the best risk predictors for long-term, mCRC development in patients with sporadic colorectal adenomas.

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.

Promotion of cell proliferation by HBXIP via upregulation of human telomerase reverse transcriptase in human mesenchymal stem cells

AIM

We previously found that the hepatitis B X-interacting protein (HBXIP) was able to promote the proliferation of cells. Telomerase activity is known to be critical in cellular senescence and its level is modulated by the regulation of the telomerase catalytic subunit, telomerase reverse transcriptase (TERT), at both the transcriptional and post-transcriptional levels. To investigate the mechanism of promoting proliferation by HBXIP, the effect of HBXIP on human TERT (hTERT) was investigated in human mesenchymal stem cells (hMSC).

METHODS

BMMS-03 cells and hMSC from the bone marrow of a 4-month-old elicited fetus, were transiently transfected with the pcDNA3-hbxip plasmid encoding the HBXIP gene and pSilencer-hbxip plasmid encoding RNA interference (RNAi) targeting HBXIP mRNA, followed by the examination of the hTERT promoter reporter gene by luciferase assay, and the detection of telomerase activity by telomeric repeat amplication protocol, respectively, as well as the expression levels of hTERT, c-Myc, and Bcl-2 by Western blot analysis.

RESULTS

The overexpression of HBXIP led to a significant upregulation of hTERT promoter activity, telomerase activity, and the expression levels of hTERT, c-Myc, and Bcl-2 in BMMS-03 cells. RNAi targeting HBXIP mRNA produced the opposite results completely.

CONCLUSION

Our data demonstrated that HBXIP significantly stimulated the transcription and expression of hTERT and increased the activity of telomerase in BMMS-03 cells, which provides a new insight into the mechanism of promoting cell proliferation by HBXIP.

Inhibition of estrogen receptor β-mediated human telomerase reverse transcriptase gene transcription via the suppression of mitogen-activated protein kinase signaling plays an important role in 15-deoxy-Δ12,14-prostaglandin J2-induced apoptosis in cancer cells

The nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR)-gamma plays a role in cancer development in addition to its role in glucose metabolism. The natural ligand of PPAR-gamma, namely, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), has been shown to possess antineoplastic activity in cancer cells. However, the mechanism underlying its antineoplastic activity remains to be elucidated. Inhibition of the expression of human telomerase reverse transcriptase (hTERT), a major determinant of telomerase activity, reportedly induces rapid apoptosis in cancer cells. In this study, we investigated the effect of 15d-PGJ(2) on hTERT expression. We found that 15d-PGJ(2) induced apoptosis in the MIAPaCa-2 pancreatic cancer cells and dose-dependently decreased hTERT mRNA and protein expression. Down-regulation of hTERT expression by hTERT-specific small inhibitory RNA also induced apoptosis. Furthermore, 15d-PGJ(2) attenuated the DNA binding of estrogen receptor (ER). MIAPaCa-2 expressed only ERbeta, and although its expression did not decrease due to 15d-PGJ(2), its phosphorylation was suppressed. Additionally, a mitogen-activated protein kinase (MAPK) kinase inhibitor decreased ERbeta phosphorylation, and 15d-PGJ(2) attenuated MAPK activity. We conclude that hTERT down-regulation by 15d-PGJ(2) plays an important role in the proapoptotic property of the latter. Furthermore, 15d-PGJ(2) inhibits ERbeta-mediated hTERT gene transcription by suppressing ERbeta phosphorylation via the inhibition of MAP kinase signaling.

Human telomerase is regulated by erythropoietin and transforming growth factor-beta in human erythroid progenitor cells

Telomerase catalytic subunit (hTERT) exerts important cellular functions including telomere homeostasis, genetic stability, cell survival and perhaps differentiation. However, the nature of external or internal signals, which regulate hTERT expression in tissues, remains poorly understood. Thus, whereas it has been described that hTERT gene is regulated along the differentiation of primitive myeloid progenitors, the effect of specific cytokines on telomerase expression in each myeloid lineage is currently unknown. Based on these considerations, we have investigated hTERT expression in erythroid cells treated with erythropoietin (EPO) and transforming growth factor beta (TGFbeta), as putative positive and negative regulators, respectively. We describe here that EPO activates hTERT gene transcription in in vitro-expanded primary erythroid precursors as well as in UT7 erythroleukemia cells. In UT7 cells, this study shows also that EPO acts through a JAK2/STAT5/c-myc axis. In contrast, TGFbeta blocks EPO signaling downstream of c-myc induction through a Smad3-dependent mechanism. Finally, hTERT appears to be efficiently regulated by EPO and TGFbeta in an opposite way in erythropoietic cells, arguing for a role of telomerase in red blood cell production.

Survivin Down-regulation Plays a Crucial Role in 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase Inhibitor-induced Apoptosis in Cancer

3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HRIs) are widely used to reduce serum cholesterol in patients with hypercholesterolemia. Previous studies have shown that HRIs can induce apoptosis in colon cancer cells. In this study, we investigated the mechanisms underlying the apoptosis-inducing effect of HRIs in greater detail. The HRI lovastatin induced apoptosis in the human colon cancer cell line SW480 by blocking the cholesterol synthesis pathway. Immunoblot analysis of antiapoptotic molecules, including survivin, XIAP, cIAP-1, cIAP-2, Bcl-2, and Bcl-X(L), revealed that only survivin expression was decreased by lovastatin. Survivin down-regulation by RNA interference induced apoptosis, and survivin overexpression rendered the cells resistant to lovastatin-induced growth inhibition. These results indicate that survivin down-regulation contributes substantially to the proapoptotic properties of lovastatin. Farnesyl pyrophosphate and geranylgeranyl pyrophosphate, two downstream intermediates in the cholesterol synthesis pathway, simultaneously reversed survivin down-regulation and the blocking of Ras isoprenylation by lovastatin. Ras isoprenylation is important for the activation of Ras-mediated signaling, including the activation of the phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway. The PI3-kinase inhibitor down-regulated survivin in SW480 cells. In addition, lovastatin blocked Ras activation and Akt phosphorylation. We conclude that survivin down-regulation is crucial in lovastatin-induced apoptosis in cancer cells and that lovastatin decreases survivin expression by inhibiting Ras-mediated PI3-kinase activation via the blocking of Ras isoprenylation.