Expression and targeting of the apoptosis inhibitor, survivin, in human melanoma

Survivin: a new target for anti-cancer therapy

Survivin is one of the most cancer-specific proteins identified to date, being upregulated in almost all human tumors. Biologically, survivin has been shown to inhibit apoptosis, enhance proliferation and promote angiogenesis. Because of its upregulation in malignancy and its key role in apoptosis, proliferation and angiogenesis, survivin is currently attracting considerable attention as a new target for anti-cancer therapies. In several animal model systems, downregulation of survivin or inactivation of its function has been shown to inhibit tumor growth. Strategies under investigation to target survivin include antisense oligonucleotides, siRNA, ribozymes, immunotherapy and small molecular weight molecules. The translation of these findings to the clinic is currently ongoing with a number of phase I/II clinical trials targeting survivin in progress. These include use of the antisense oligonucleotide LY2181308, the low molecular weight molecule inhibitor YM155 and survivin-directed autologous cytotoxic T lymphocytes. The optimum use of survivin antagonists in the treatment of cancer is likely to be in combination with conventional cancer therapies.

Latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus (KSHV) upregulates survivin expression in KSHV-Associated B-lymphoma cells and contributes to their proliferation

Survivin is a master regulator of cell proliferation and cell viability and is highly expressed in most human tumors. The molecular network linked to survivin expression in tumors has not been completely elucidated. In this study, we show that latency-associated nuclear antigen (LANA), a multifunctional protein of Kaposi's sarcoma-associated herpesvirus (KSHV) that is found in Kaposi's sarcoma tumors, upregulates survivin expression and increases the proliferation of KSHV-infected B cells. Analysis of pathway-specific gene arrays showed that survivin expression was highly upregulated in BJAB cells expressing LANA. The mRNA levels of survivin were also upregulated in HEK 293 and BJAB cells expressing LANA. Similarly, protein levels of survivin were significantly higher in LANA-expressing, as well as KSHV-infected, cells. Survivin promoter activity assays identified GC/Sp1 and p53 cis-acting elements within the core promoter region as being important for LANA activity. Gel mobility shift assays revealed that LANA forms a complex with Sp1 or Sp1-like proteins bound to the GC/Sp1 box of the survivin promoter. In addition, a LANA/p53 complex bound to the p53 cis-acting element within the survivin promoter, indicating that upregulation of survivin expression can also occur through suppression of p53 function. Furthermore, immunohistochemistry analyses revealed that survivin expression was upregulated in KSHV-associated Kaposi's sarcoma tissue, suggesting that LANA plays an important role in the upregulation of survivin expression in KSHV-infected endothelial cells. Knockdown of survivin expression by lentivirus-delivered small hairpin RNA resulted in loss of cell proliferation in KSHV-infected cells. Therefore, upregulation of survivin expression in KSHV-associated human cells contributes to their proliferation.

Construction of a survivin promoter-mediated adeno-associated virus expression vector carrying a fusion gene constituted with cytosine deaminase and survivin mutant

AIM: To construct a recombinant survivin promoter (SurP)-mediated adeno-associated virus expression vector carrying a fusion gene constituted with cytosine deaminase (CD) gene and glycin-linked survivin mutant (glySurMut), and to examine the expression of CDglySurMut fusion protein in cancer cells transfected with this vector.

METHODS: The CD gene and glySurMut fragments were amplified by polymerase chain reaction (PCR), and cloned into the adeno-associated virus expression vector PAM with survivin promoter (PAM/SurP). The recombinant vector was transformed into E.coli DH5α. and the positive clones were selected. The plasmid DNA was identified using restriction enzyme analysis and sequencing. The recombinant vector pAM/SurP-CDglySurMut was transfected into gastric cancer cells MKN45. The expression of fusion protein in cancer cells was detected using Western blot.

RESULTS: The CD gene and glySurMut were cloned from E.coli and gastric cancer cells, respectively. The restrictive enzyme analysis and sequencing showed that the fusion gene of CD and glySurMut was successfully inserted into the PAM/SurP vector. Western blot showed that the recombinant vector expressed the CDglySurMut fusion protein in gastric cancer cells.

CONCLUSION: Our results show the pAM/SurP-CDglySurMut vector can efficiently express the recombinant CDglySurMut fusion protein in gastric cancer cells, thus provides experiment evidence for targeting cancer gene therapy using this pAM/SurP-CDglySurMut vector.

Melanoma biomarkers: current status and vision for the future

Melanoma is the leading cause of death from skin cancer in industrialized countries. Clinical and histological variables such as primary tumor invasion, ulceration, and lymph node status might fail to identify early-stage disease that will eventually progress. Tumor biomarkers might help to identify patients with early-stage melanoma who are likely to develop advanced disease and would benefit from additional therapies. These biomarkers offer the possibility of improved tumor staging through the molecular detection of microscopic lymph node metastases that are not visible on routine histological examination. We focus on biomarkers localized to the tumor tissue and those of prognostic value. We give an overview of the melanoma biomarkers that are most helpful for prediction of patients' outcomes, and discuss the primary melanoma biomarkers that have been shown to be of prognostic significance independent of primary tumor thickness and other common clinical prognostic indicators. Although such tumor-associated biomarkers are thought to have the greatest potential, a lack of reliable data makes their true clinical utility difficult to determine. We conclude that several biomarkers show promise in early studies; however, additional large-scale studies are warranted. We suggest cautious optimism for the field of melanoma biomarkers, which we expect to be translated into clinical practice over the next few years.

Prognostic value of survivin in locally advanced prostate cancer: study based on RTOG 8610

PURPOSE

To examine the prognostic value of nuclear and cytoplasmic survivin expression in men with locally advanced prostate cancer who were enrolled in Radiation Therapy Oncology Group (RTOG) protocol 8610.

METHODS AND MATERIALS

RTOG 8610 was a Phase III randomized study comparing the effect of radiotherapy plus short-term androgen deprivation with radiotherapy alone. Of the 456 eligible patients, 68 patients had suitably stained tumor material for nuclear survivin analysis and 65 patients for cytoplasmic survivin.

RESULTS

Compared with patients with nuclear survivin intensity scores of <or=191.2, those with intensity scores >191.2 had significantly improved prostate cancer survival (hazard ratio [HR], 0.45; 95% confidence interval [CI], 0.20-1.00, p = 0.0452). On multivariate analysis, nuclear survivin intensity scores >191.2 were significantly associated with improved overall survival (HR, 0.46; 95% CI, 0.25-0.86; p = 0.0156) and prostate cancer survival (HR, 0.36; 95% CI, 0.16-0.84; p = 0.0173). On univariate analysis, compared with patients with cytoplasmic survivin integrated optical density <or=82.7, those with an integrated optical density >82.7 showed a significantly increased risk of local progression (HR, 2.49; 95% CI, 1.03-6.01; p = 0.0421).

CONCLUSION

Nuclear overexpression of survivin was associated with improved overall and prostate cancer survival on multivariate analysis, and cytoplasmic overexpression of survivin was associated with increased rate of local progression on univariate analysis in patients with locally advanced prostate cancer treated on RTOG 8610. Our results might reflect the different functions of survivin and its splice variants, which are known to exist in distinct subcellular compartments.

Survivin: key regulator of mitosis and apoptosis and novel target for cancer therapeutics

Survivin, a member of the family of inhibitor of apoptosis proteins, functions as a key regulator of mitosis and programmed cell death. Initially, survivin was described as an inhibitor of caspase-9. However, over the last years, research studies have shown that the role of survivin in cancer pathogenesis is not limited to apoptosis inhibition but also involves the regulation of the mitotic spindle checkpoint and the promotion of angiogenesis and chemoresistance. Survivin gene expression is transcriptionally repressed by wild-type p53 and can be deregulated in cancer by several mechanisms, including gene amplification, hypomethylation, increased promoter activity, and loss of p53 function. This article reviews the multiple functions of survivin in the regulation of apoptosis, the promotion of tumorigenesis, and the development of survivin inhibitors as a novel anticancer therapeutic strategy.

Efficient generation of survivin-specific cytotoxic T lymphocytes from healthy persons in vitro: quantitative and qualitative effects of CD4+ T cells

For the adoptive immunotherapy and the study of cytotoxic T lymphocytes (CTLs) in human, efficient in vitro generation of CTLs is needed. However, it is still difficult to induce T cells specific for naïve antigens in vitro even though dendritic cells (DCs) as potent APCs are used. In this study, we investigated quantitative and qualitative effects of CD4+ T cells during in vitro stimulation of CD8+ T cells from healthy donors using DCs transduced with adenovirus vector expressing human survivin (Adv-survivin). CTLs were not efficiently induced in the absence of CD4+ T cells or in CD25+ depleted CD4+ T cells. When the ratio of CD4+:CD8+ T cells was quantitatively decreased from 2:1 to 1:2, proliferation of CTLs specific for survivin was gradually increased. Because DCs pulsed with HCMV pp65 protein could activate CD4+ T cells to secrete Th1 cytokines, the use of pp65 protein as an adjuvant induced higher numbers and frequencies of CTLs. Furthermore, Th1 conditioning of CD4+ T cells augmented this generation of CTLs. These results suggest that both quantitative and qualitative modulation of CD4+ T cells including the number and Th1 polarization may be required for the efficient induction of CTLs specific for tumor antigens in vitro.

Nuclear expression of survivin portends a poor prognosis in Merkel cell carcinoma

Inhibition of apoptosis is a critical step in tumorigenesis in many cancers, including Merkel cell carcinoma; however, the exact regulatory mechanisms are not fully understood. Survivin is an inhibitor of apoptosis that is undetectable in most terminally differentiated normal human tissues, strongly expressed in embryonic and fetal organs and is strongly expressed in many different human cancers. In this study, we investigated the expression of survivin in cutaneous Merkel cell carcinoma using immunohistochemistry and correlated the findings with long-term clinical follow-up. We collected and immunostained 19 cases of Merkel cell carcinoma with antibodies to survivin. The median patient age was 79 years, with an average follow-up of 17 months, and a male/female ratio of 7:11. All but one sample represented primary lesions and two cases were obtained from one patient. Clinical follow-up was obtained in 15 cases (79%). All 19 cases of Merkel cell carcinoma demonstrated strong immunoreactivity for survivin. Survivin protein was localized and classified into predominately nuclear (N=8) or cytoplasmic (N=4) compartments. A mixed pattern of survivin expression was also seen in three cases. Cases with a nuclear staining pattern were distinguished by an aggressive clinical course, with seven of eight patients developing metastases or dead of disease on follow-up. Furthermore, all of the cases with predominately cytoplasmic survivin localization (N=4) were free of disease on follow-up. Merkel cell carcinomas represent aggressive malignancies regulated by apoptotic pathways. We demonstrate that survivin, a protein with a dual role in inhibition of apoptosis and regulation of cellular proliferation is expressed in Merkel cell carcinoma. Moreover, nuclear subcellular localization of survivin in Merkel cell carcinomas may portend a poor prognosis and identification of these cases may assist clinical management.

Comparison of pHH3, Ki-67, and survivin immunoreactivity in benign and malignant melanocytic lesions

Differentiating malignant melanoma from benign melanocytic lesions can be challenging. We undertook this study to evaluate the use of the immunohistochemical mitosis marker phospho-Histone H3 (pHH3) and the proliferation markers Ki-67 and survivin in separating malignant melanoma from benign nevi. Sixty-six melanocytic lesions (18 malignant melanomas, 8 Spitz nevi, 20 dysplastic nevi, and 20 compound nevi) were stained with antibodies to pHH3, Ki-67, and survivin. No pHH3 expression was detected in the dermis of compound and dysplastic nevi. Rare mitoses were observed in the superficial dermis in 3 of 8 Spitz nevi (37%). Staining for pHH3 was higher in malignant melanomas [average 25 per 10 high-power field (HPF), range 2-75 per 10 HPF] than in Spitz nevi (average 0.5 per 10 HPF, range 0-2 per 10 HPF) and was heterogeneously distributed in the malignant melanomas compared with a superficial dermal location in Spitz nevi. There was no cytoplasmic staining for survivin in any of the 66 melanocytic lesions and no nuclear staining in any of the benign ones. Survivin nuclear staining was present in 12 of 18 cases of malignant melanoma (67%) with an average index of 7% (range 0%-15%). In benign melanocytic lesions, the Ki-67 index was less than 5% (range 0%-4%) and staining was present close to the dermo-epidermal junction compared with an average index of 27% in melanomas (range 5%-50%) and a generally heterogeneous pattern of staining throughout the dermis. pHH3 and Ki-67 can be useful adjuncts to histopathology to separate malignant melanoma from benign nevi. pHH3 is especially useful to highlight mitoses and to rapidly assess the mitotic activity in melanocytic lesions.

Apoptosis pathways and oncolytic adenoviral vectors: promising targets and tools to overcome therapy resistance of malignant melanoma

In the last decades melanoma incidence has been increasing worldwide, while mortality remained on a high level. Until now, there is no suitable therapy for metastasized melanoma, which could lead to a significant increase in overall survival. Apoptosis deficiency is supposed to be a critical factor for therapy resistance, and previous work has characterized the basic mechanisms of apoptosis regulation in melanoma. Genes and strategies suitable for efficient induction of apoptosis in melanoma cells were identified, which are based on proapoptotic Bcl-2 proteins (Bcl-x(S), Bcl-x(AK), Bik/Nbk and Bax) as well as on tumor necrosis factor (TNF)-related death ligands (CD95L/Fas ligand and TNF-related apoptosis-inducing ligand, TRAIL). Proapoptotic genes may be employed in improved gene therapeutic strategies, based on conditional oncolytic adenoviral vectors.

Protective role of the inhibitor of apoptosis protein, survivin, in toxin-induced acute renal failure

Acute renal failure (ARF) is a major worldwide cause of morbidity and mortality, lacking specific targeted, effective therapies. Renal tubular cell apoptosis has been recognized to play a critical role in the pathogenesis of ARF, yet few studies have evaluated whether intervention in apoptotic pathways can ameliorate the deterioration in renal function associated with ARF. Using transgenic mice with diminished levels of the inhibitor of apoptosis protein, survivin, we show that survivin is required to protect the kidney from apoptosis, to suppress renal expression of p53, and to ameliorate renal dysfunction in two models of ARF. Gene delivery of survivin to wild-type mice and mice with 50% levels of survivin, prior to or at the time of induction of ARF, interferes with the deterioration of renal function and preserves the integrity of the kidneys and the renal tubular cells by inhibiting activation of apoptotic pathways in the kidneys and suppressing expression of p53. These results encourage further evaluation of survivin, its active structural domains, and other inhibitors of apoptosis proteins, for preventing and/or treating acute renal failure.

Bim Expression Is Reduced in Human Cutaneous Melanomas

Bim is a BH3-only protein belonging to the Bcl-2 family of apoptotic regulators. Upon activation, Bim can antagonize all the prosurvival Bcl-2 proteins, leading to apoptosis. To investigate whether Bim plays a role in melanoma progression, we used tissue microarray and immunohistochemistry to measure Bim expression in 52 cases of dysplastic nevi, 159 cases of primary melanomas and 52 cases of melanoma metastases, and evaluated the prognostic value of Bim expression. Our results showed that Bim expression is reduced as melanoma progresses. Significant differences for Bim staining pattern were observed between dysplastic nevi and metastatic melanomas (P<0.001, chi2 test), and between primary melanomas and metastatic melanomas (P<0.001, chi2 test). Moreover, reduced Bim expression is significantly correlated with poor 5-year survival of melanoma patients but failed to be an independent prognostic factor by Cox regression analysis. Our data suggest that Bim loss may play an important role in melanoma progression.

The universal character of the tumor-associated antigen survivin

Survivin is expressed in most human neoplasms, but is absent in normal, differentiated tissues. Survivin is a bifunctional inhibitor of apoptosis protein that has been implicated in protection from apoptosis and regulation of mitosis. Several clinical trials targeting survivin with a collection of different approaches from small molecule antagonists to immunotherapy are currently under way. With regard to the latter, spontaneous anti-survivin T-cell reactivity has been described in cancer patients suffering from a huge range of cancers of different origin, e.g., breast and colon cancer, lymphoma, leukemia, and melanoma. Thus, survivin may serve as a universal target antigen for anticancer immunotherapy. Accordingly, down-regulation of survivin as a means of immune escape would severely inflict the survival capacity of tumor cells, which highlights this protein as a prime target candidate for therapeutic vaccinations against cancer. Data from several ongoing phase I/II trials targeting survivin for patients with advanced cancer will provide further information about this idea.

N-acetylcysteine protects melanocytes against oxidative stress/damage and delays onset of ultraviolet-induced melanoma in mice

PURPOSE

UV radiation is the major environmental risk factor for melanoma and a potent inducer of oxidative stress, which is implicated in the pathogenesis of several malignancies. We evaluated whether the thiol antioxidant N-acetylcysteine (NAC) could protect melanocytes from UV-induced oxidative stress/damage in vitro and from UV-induced melanoma in vivo.

EXPERIMENTAL DESIGN

In vitro experiments used the mouse melanocyte line melan-a. For in vivo experiments, mice transgenic for hepatocyte growth factor and survivin, shown previously to develop melanoma following a single neonatal dose of UV irradiation, were given NAC (7 mg/mL; mother's drinking water) transplacentally and through nursing until 2 weeks after birth.

RESULTS

NAC (1-10 mmol/L) protected melan-a cells from several UV-induced oxidative sequelae, including production of intracellular peroxide, formation of the signature oxidative DNA lesion 8-oxoguanine, and depletion of free reduced thiols (primarily glutathione). Delivery of NAC reduced thiol depletion and blocked formation of 8-oxoguanine in mouse skin following neonatal UV treatment. Mean onset of UV-induced melanocytic tumors was significantly delayed in NAC-treated compared with control mice (21 versus 14 weeks; P = 0.0003).

CONCLUSIONS

Our data highlight the potential importance of oxidative stress in the pathogenesis of melanoma and suggest that NAC may be useful as a chemopreventive agent.

A phase II study of ispinesib (SB-715992) in patients with metastatic or recurrent malignant melanoma: a National Cancer Institute of Canada Clinical Trials Group trial

To assess the response rate and toxicity of the kinesin spindle protein (KSP) inhibitor, ispinesib, in malignant melanoma. Seventeen patients were enrolled from April to November 2005. Ispinesib was administered as a 1-hour infusion at a dose of 18 mg/m2 once every 3 weeks until disease progression. No objective responses were seen. Six patients (35%) had a best response of stable disease for a median duration of 2.8 months. Disease progression was documented in 9 (53%) after 1 or 2 cycles. Eighty-eight percent of patients received > or =90% of planned dose intensity. Grade 3 non-hematologic toxicities included dizziness (1) and blurred vision (1). There was one episode of febrile neutropenia, but no grade 3 or 4 biochemical adverse events. Pharmacokinetics was consistent with prior studies. KSP immunoreactivity was seen in 14 of 16 available archival tissue samples (88%). Ispinesib can be safely administered using the dose and schedule employed, with mild hematologic and non-hematologic toxicity. No objective responses were observed, and further development of single-agent ispinesib in malignant melanoma is not recommended. Although KSP expression appears to be common in melanoma, KSP may not be a suitable target for its treatment.

Survivin repression by p53, Rb and E2F2 in normal human melanocytes

The inhibitor of apoptosis protein survivin is a dual mediator of apoptosis resistance and cell cycle progression and is highly expressed in cancer. We have shown previously that survivin is up-regulated in melanoma compared with normal melanocytes, is required for melanoma cell viability, and that melanocyte expression of survivin predisposes mice to ultraviolet-induced melanoma and metastasis. The mechanism of survivin up-regulation in the course of melanocyte transformation and its repression in normal melanocytes, however, has not been clearly defined. We show here that p53 and retinoblastoma (Rb), at basal levels and in the absence of any activating stimuli, are both required to repress survivin transcription in normal human melanocytes. Survivin repression in melanocytes does not involve alterations in protein stability or promoter methylation. p53 and Rb (via E2Fs) regulate survivin expression by direct binding to the survivin promoter; p53 also affects survivin expression by activating p21. We demonstrate a novel role for E2F2 in the negative regulation of survivin expression. In addition, we identify a novel E2F-binding site in the survivin promoter and show that mutation of either the p53- or E2F-binding sites is sufficient to increase promoter activity. These studies suggest that compromise of either p53 or Rb pathways during melanocyte transformation leads to up-regulation of survivin expression in melanoma.

Understanding spitzoid tumours: new insights from molecular pathology

Spitzoid tumours are a morphologically diverse group of lesions that share histological similarity to the Spitz naevus, a benign melanocytic skin tumour. Distinguishing classic Spitz naevi from cutaneous malignant melanoma is usually achievable on standard histology sections, but occasionally equivocal lesions are encountered that show features intermediate between these two entities and consequently generate considerable clinical and histopathological concern. The nomenclature and diagnostic criteria for spitzoid lesions are not standardized and this article begins by considering the adverse effect this has on our understanding of spitzoid tumour biology. Investigations of some of the hallmark features of cancer and neoplasia in spitzoid tumours are described, and the contribution of these studies to our understanding of spitzoid tumour biology is considered, along with their potential diagnostic utility. These studies compare spitzoid tumours with better-characterized melanocytic lesions, and from such comparisons assumptions concerning the biological nature of different spitzoid tumours can be made. In contrast, investigations of the mitogen-activated protein kinase (MAPK) pathway and DNA gains and losses have suggested that Spitz naevi may be genetically distinct from other melanocytic tumours. The studies that led to this conclusion are reviewed, as well as subsequent work examining whether the same applies to all spitzoid tumours. Possible explanations for the considerable inconsistencies within some of these data are explored. Finally, potential pathways of tumour progression within spitzoid lesions are considered, with an emphasis placed upon insights gained from investigations of MAPK genes and DNA gains and losses.

Oncogenic c-H-ras deregulates survivin expression: An improvement for survival

Survivin protein accomplishes two basic functions: cell cycle regulation and control of apoptosis. It is only expressed in G2/M phase and it influences rescue pathways in apoptosis-induced cells. Overexpression of constitutive active c-H-ras in HeLa, or induction of c-H-ras in a stable HeLaDiR cell line, led to sustained survivin expression in all cell cycle phases and even protected cells from drug induced apoptosis. siRNA-mediated silencing of survivin reversed this protection. Here we link the anti-apoptotic property of survivin to its cell cycle (in)dependent regulation via the activity of oncogenic c-H-ras.

Induction of G2/M arrest and apoptosis by sesquiterpene lactones in human melanoma cell lines

Malignant melanoma is a highly aggressive tumor which frequently resists chemotherapy, therefore, the search for new agents for its treatment is of great importance. In this study, we purified the sesquiterpene lactones (SLs), Tomentosin and Inuviscolide from Inula viscosa (Compositae) leaves and studied their anti-cancer potency against human melanoma cell lines in order to develop new agents for melanoma treatment. SLs inhibited the proliferation of three human melanoma cell lines: SK-28, 624 mel and 1363 mel in a dose-dependent manner. We further investigated SLs mechanism of action using SK-28 as a representative cell line model. SLs caused cell-cycle arrest at G(2)/M, accompanied by the appearance of a sub-G0 fraction, indicative of apoptotic cell death. Induction of apoptosis was further confirmed by changes in membrane phospholipids, changes in mitochondrial membrane potential (DeltaPsi) and by detection of Caspase-3 activity. Rapid inhibitory phosphorylation of Cdc2 (Thr14 and Tyr15) was seen early after treatment, followed by a later decrease in the expression level of both Cyclin b1 and Cdc2. Induction of p53 and p21(waf1) proteins and phosphorylation of p53 at Ser15 were also detected early after treatment. The anti-apoptotic proteins, p65 subunit of nuclear factor kappaB (NF-kappaB), and Survivin were reduced in a dose-dependent manner. Taken together, these changes partially explain the ability of the SLs to induce G(2)/M arrest and apoptosis. Induction of apoptosis by Tomentosin and Inuviscolide in human aggressive melanoma cell lines has high pharmacological value and implies that SLs might be developed as new agents for melanoma treatment.

Melanocyte expression of survivin promotes development and metastasis of UV-induced melanoma in HGF-transgenic mice

We previously found the apoptosis inhibitor Survivin to be expressed in melanocytic nevi and melanoma but not in normal melanocytes. To investigate the role of Survivin in melanoma development and progression, we examined the consequences of forced Survivin expression in melanocytes in vivo. Transgenic (Tg) mouse lines (Dct-Survivin) were generated with melanocyte-specific expression of Survivin, and melanocytes grown from Dct-Survivin mice expressed Survivin. Dct-Survivin melanocytes exhibited decreased susceptibility to UV-induced apoptosis but no difference in proliferative capacity compared with melanocytes derived from non-Tg littermates. Induction of nevi in Dct-Survivin and non-Tg mice by topical application of 7,12-dimethylbenz(a)anthracene did not reveal significant differences in lesion onset (median, 10 weeks) or density (4 lesions per mouse after 15 weeks). Dct-Survivin mice were bred with melanoma-prone MH19/HGF-B6 Tg mice, and all progeny expressing either individual, neither, or both (Survivin/HGF) transgenes were UV-treated as neonates and then monitored for 43 weeks. Melanocytes in neonatal Survivin+/HGF+ mouse skin were less susceptible to UV-induced apoptosis than those from Survivin-/HGF+ mice. Onset of melanocytic tumors was earlier (median, 18 versus 24 weeks; P = 0.01, log-rank test), and overall tumor density was greater (7.7 versus 5.2 tumors per mouse; P = 0.04) in Survivin+/HGF+ compared with Survivin-/HGF+ mice. Strikingly, melanomas arising in Survivin+/HGF+ mice showed a greater tendency for lymph node (35% versus 0%; P = 0.04) and lung (53% versus 22%) metastasis and lower rates of spontaneous apoptosis than those in Survivin-/HGF+ mice. These studies show a role for Survivin in promoting both early and late events of UV-induced melanoma development in vivo.

Nuclear survivin is associated with disease recurrence and poor survival in patients with cutaneous malignant melanoma

AIMS

Survivin is expressed in neoplastic cells and appears to be associated with resistance to therapy and shorter survival in various types of tumours. The aim of the present study was to determine whether nuclear or cytoplasmic expression of survivin is related to disease recurrence and overall survival of patients with Stage I and II melanoma according to the American Joint Committee on Cancer (AJCC) staging system.

METHODS AND RESULTS

Immunohistochemistry was performed on formalin-fixed paraffin-embedded sections of primary cutaneous melanoma from 50 patients. Survival rates were estimated using the Kaplan-Meier method and compared using the log rank test. Association of clinical variables (gender, age, tumour location, thickness, Clark level and AJCC stage) with survivin expression was analysed by Fisher's exact test. Patients with nuclear immunoreactivity for survivin had an increased risk of disease recurrence during the first three postoperative years (P < 0.05) and of death (P < 0.05). Cytoplasmic immunoreactivity was not correlated with either survival or clinical variables.

CONCLUSIONS

Nuclear presence of survivin may be an independent biomarker for disease recurrence and overall survival in patients with Stage I and II melanoma.

Roles of survivin isoforms in the chemopreventive actions of NSAIDS on colon cancer cells

NSAIDs downregulate survivin (an apoptosis inhibitor), increase apoptosis and reduce growth of colon polyps and cancers. Recently, anti- and pro-apoptosis isoforms of survivin were identified. The roles of these isoforms in NSAID-induced colon cancer cell death have not been examined, and is the focus of this study. The anti-apoptosis isoforms, wild-type (WT) survivin and survivin-DeltaEx3, and the pro-apoptosis isoform, survivin-2b, were present in HT-29 and RKO cells. Indomethacin treatment significantly decreased WT survivin and survivin-DeltaEx3 (30.5+/-10.4% and 20.3+/-6.7%, respectively) but not survivin-2b mRNA in RKO cells. In HT-29 cells, all three isoform mRNAs were slightly decreased by indomethacin treatment. Consistently, indomethacin treatment dramatically reduced WT survivin protein in RKO but not HT-29 cells. Indomethacin treatment increased apoptosis and general cell death more significantly in RKO cells (75.7+/-1.1% cell death at 48 h) than in HT-29 cells (25.4+/-3.7% cell death at 48 h). Anti-sense suppression of survivin-2b mRNA increased resistance of both RKO and HT-29 cells to indomethacin. These data support a role for survivin isoforms in colon cancer cell apoptosis, and thus in prevention of colon cancer growth by NSAIDs.

Effects of JC virus infection on anti-apoptotic protein survivin in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system resulting from the productive infection of oligodendrocytes by the opportunistic polyomavirus JC virus (JCV). Apoptosis is a host defense mechanism to dispose of damaged cells; however, certain viruses have the ability to deregulate apoptotic pathways to complete their life cycles. One such pathway involves survivin, a member of the inhibitor of apoptosis family, which is abundantly expressed during development in proliferating tissues but should be absent in normal, terminally differentiated cells. Immunohistochemistry performed in 20 cases of PML revealed the presence of survivin in JCV-infected oligodendrocytes and bizarre astrocytes within demyelinated plaques. Survivin up-regulation was also found in oligodendroglial and astrocytic cultures infected with JCV. Cell cycle analysis and DNA laddering demonstrated a significantly lower number of cells undergoing apoptosis on JCV infection compared with noninfected cultures; small interfering RNA inhibition of survivin resulted in a dramatic increase in apoptotic cells in JCV-infected cultures. This is the first report describing the activation of survivin by JCV infection in vitro and in PML clinical cases. These observations provide new insights into the anti-apoptotic mechanisms used by JCV to complete its lytic cycle and may suggest new therapeutic targets for PML.

Nonspecific cellular accumulation of 99mTc-labeled oligonucleotides in culture is influenced by their guanine content

Specific accumulation of radiolabeled antisense oligonucleotides as a result of binding by an antisense mechanism to target mRNAs in tumor has been repeatedly observed. However, the mechanisms responsible for nonspecific cellular accumulation remain almost completely unexplored. We have occasionally observed in cell culture nonspecific accumulations of 99mTc-labeled sense, scrambled or random control oligonucleotides in tumor cells comparable to or even higher than those of the corresponding antisense oligonucleotides. We have also observed that these nonspecific accumulations of control oligonucleotides are sequence dependent. To explore the influence of base composition on nonspecific accumulation, we used MCF-7 breast cancer cells, along with 10 uniform phosphorothioates and 5 uniform phosphodiesters oligonucleotides. Three of the phosphorothioates were antisense against different sites within the survivin mRNA, and two were the corresponding sense and scrambled controls. In addition, the accumulations in MCF-7 cells of radiolabeled poly A, poly C, poly T and poly GGGA phosphorothioate oligonucleotides were also studied to explore the influence of each nitrogenous base on the nonspecific cell accumulations of phosphorothioate oligonucleotides. Our results show that guanine content is an important determinant of nonspecific cellular accumulations under the conditions of this investigation. If this observation can be shown to be universally applicable to other cell types, then the selection of control sequences in studies of antisense tumor targeting should avoid those that are guanine rich, if possible.

Inhibition of signal transducer and activator of transcription 3 activity results in down-regulation of Survivin following irradiation

Signal transducer and activator of transcription 3 (Stat3) and Survivin are constitutively up-regulated in various human tumor cells. We previously found Survivin to be significantly reduced in response to radiation in human umbilical vein endothelial cells (HUVEC) but not in tumor cell lines. In this study, we examined the effect of Stat3 on Survivin expression in irradiated HUVECs and breast cancer cells. We also studied how inhibition of Stat3 and Survivin activity affects cell survival and angiogenesis following irradiation. We determined that Survivin was significantly increased by overexpression of an active Stat3 (Stat3-C). Following irradiation, the level of phospho-Stat3 Tyr(705), but not phospho-Stat3 Ser(727), was reduced in HUVECs, whereas it remained unchanged in irradiated breast cancer cells. Correspondingly, Stat3 DNA-binding activity following irradiation was specifically down-regulated in HUVECs but not in breast cancer cells. Mutation of Tyr(705) abolished radiation-induced down-regulation of Survivin. Clonogenic and endothelial cell morphogenesis assays suggested that DN-Stat3 and DN-Survivin together resulted in the greatest radiosensitization of MDA-MB-231, decreasing angiogenesis and cell survival. In summary, Stat3 modulates Survivin, and both are potential therapeutic targets for radiation sensitization in breast cancer.

Characterization of the 12C4 survivin monoclonal antibody and insight into the expression of survivin in human adult tissues

AIMS

To elucidate the expression and regulation of survivin in normal tissues.

METHODS AND RESULTS

A novel monoclonal antibody (12C4) to survivin was generated. Application of this antibody to determine survivin expression in human normal adult tissues revealed that most adult tissues do not express survivin and, where it is present, survivin is largely restricted to a small subset of epithelial cells and cells with proliferative potential such as thymus. Survivin expression among positive tissues showed individual variations, ranging from zero to < 5% positive cells in epithelial cell populations. Testis is the only human adult tissue highly expressing survivin, with 60-70% positivity in the nuclei of spermatogonia. Consistent with deregulated expression of survivin associated with oncogenesis, we found that certain ligands and transcription factors differentially modulate survivin promoter activity in cancer cells versus normal/untransformed cells.

CONCLUSION

Deregulation of survivin transcription controls in individual epithelial cells may contribute to oncogenesis in various human adult tissues.

Antisense-mediated melanoma inhibitor of apoptosis protein downregulation sensitizes G361 melanoma cells to cisplatin

Malignant melanoma is an aggressive form of skin cancer that is highly resistant to conventional therapies. The melanoma inhibitor of apoptosis protein is a potent inhibitor of apoptosis and is overexpressed in melanoma cells, but undetectable in most normal tissues including melanocytes. We designed 20-mer phosphorothioate antisense oligonucleotides complementary to five putatively single-stranded sites on the melanoma inhibitor of apoptosis protein mRNA and investigated their ability to sensitize G361 melanoma cells to cisplatin. Inhibition of melanoma inhibitor of apoptosis protein mRNA and protein expression were measured by real-time polymerase chain reaction and immunoblotting. Cell viability and apoptosis were quantitated by colorimetric viability assays and by annexin V staining, respectively. Oligonucleotide M706 was identified as the most efficient antisense sequence which downregulated melanoma inhibitor of apoptosis protein mRNA and protein levels in G361 cells by 68 and 78%, respectively. The specificity of target downregulation was confirmed using scrambled sequence control oligonucleotides that only marginally decreased melanoma inhibitor of apoptosis protein expression. Whereas downregulation of melanoma inhibitor of apoptosis protein moderately inhibited cell growth by 26%, in combination with cisplatin, this resulted in a supra-additive effect with almost 57% reduction in G361 cell viability compared with cisplatin alone (17%) (P<0.05). Cell death was mainly due to apoptosis as demonstrated by a 3- to 4-fold increase in annexin V-positive cells and typical morphological changes compared with controls. In summary, we describe a new antisense oligonucleotide that efficiently downregulates melanoma inhibitor of apoptosis protein expression and sensitizes melanoma cells to cisplatin.

Effect of downregulation of survivin expression on radiosensitivity of human epidermoid carcinoma cells

PURPOSE

The expression of survivin, a member of the inhibitor-of-apoptosis protein family, is elevated in many types of human cancer. High survivin expression has been associated with poor patient prognosis and tumor resistance to chemotherapy and radiotherapy. The purpose of this study was to compare the radiosensitizing effects of five agents that target survivin on their relative ability to downregulate survivin expression.

METHODS AND MATERIALS

The human epidermoid carcinoma cell line A431 was treated with adenoviral-mediated wild-type p53, antisense to survivin, the mitogen-activated protein kinase inhibitor PD98059, the cyclin-dependent kinase inhibitor Purvalanol A, or the histone deacetylase inhibitor trichostatin A. The radiosensitizing effects of these treatments were determined by clonogenic survival curve analysis and their abilities to suppress survivin expression by Western blot analysis.

RESULTS

All the strategies were shown to radiosensitize A431 cells. This effect correlated with their abilities to downregulate survivin.

CONCLUSION

Expression of survivin appears to confer a radioresistant phenotype that can be overcome using several clinically achievable strategies that target survivin either specifically or nonspecifically.

Enhanced Killing of Melanoma Cells by Simultaneously Targeting Mcl-1 and NOXA

By deciphering the dysregulation of apoptosis in melanoma cells, new treatment approaches exploiting aberrant control mechanisms regulating cell death can be envisioned. Among the Bcl-2 family, a BH3-only member, NOXA, functions in a specific mitochondrial-based cell death pathway when melanoma cells are exposed to a proteasome inhibitor (e.g., bortezomib). Some therapeutic agents, such as bortezomib, not only induce proapoptotic Bcl-2 family members and active conformational changes in Bak and Bax but also are associated with undesirable effects, including accumulation of antiapoptotic proteins, such as Mcl-1. To enhance the bortezomib-mediated killing of melanoma cells, the apoptotic pathway involving NOXA was further investigated, leading to identification of an important target (i.e., the labile Bcl-2 homologue Mcl-1 but not other survival proteins). To reduce Mcl-1 levels, melanoma cells were pretreated with several different agents, including Mcl-1 small interfering RNA (siRNA), UV light, or the purine nucleoside analogue fludarabine. By simultaneously triggering production of NOXA (using bortezomib) as well as reducing Mcl-1 levels (using siRNA, UV light, or fludarabine), significantly enhanced killing of melanoma cells was achieved. These results show binding interactions between distinct Bcl-2 family members, such as NOXA and Mcl-1, in melanoma cells, paving the way for novel and rational therapeutic combination strategies, which target guardians of the proapoptotic Bak- and Bax-mediated pathways, against this highly aggressive and often fatal malignancy.

HLA-A24 and survivin: possibilities in therapeutic vaccination against cancer

Recently, it was described that an HLA-A24 restricted peptide derived from the survivin splice variant survivin-2B can be recognized by CD8(+) cytotoxic T-cells. The identification of an HLA-A24 epitope is critical for survivin-based immunotherapy as HLA-24 is the most frequent HLA allele in Asia. Consequently, this survivin-2B epitope is already a target in a clinical study in patients with advanced or recurrent colorectal cancer expressing survivin. However, the splice variant survivin-2B has been described to be pro-apoptotic, and is only expressed at low levels in most malignant tissues. Furthermore, survivin-2B expression are significantly decreased in later tumor stages and inversely correlated with tumor differentiation and invasion. Consequently, survivin is a more general vaccination candidate than the splice variant survivin-2B. Here, we on the basis of spontaneous immune responses in HLA-A24+ cancer patients describes that a HLA-A24-restricted survivin epitopes does indeed exist. Consequently, this epitope is an attractive target for the ongoing survivin-based peptide immunotherapy against cancer.

Survivin, a cancer target with an emerging role in normal adult tissues

Survivin, an inhibitor of apoptosis protein, is highly expressed in most cancers and associated with chemotherapy resistance, increased tumor recurrence, and shorter patient survival, making antisurvivin therapy an attractive cancer treatment strategy. However, growing evidence indicates that survivin is expressed in normal adult cells, particularly primitive hematopoietic cells, T lymphocytes, polymorphonuclear neutrophils, and vascular endothelial cells, and may regulate their proliferation or survival. In preclinical animal models, targeted antisurvivin therapies show efficacy without overt toxicity. However, consequences of prolonged survivin disruption in normal cells, particularly those associated with continuous renewal, have not been clearly determined. Understanding the role of survivin in normal versus malignant cells will be important in identifying strategies that maximally disrupt survivin in cancer cells with minimal effect on normal tissues. In this review, we summarize the prognostic relevance of survivin in cancer that justifies the pursuit of antisurvivin therapies and discuss differences in survivin expression between normal and cancer cells. We subsequently review expression of survivin in normal adult tissues and evaluate preclinical antisurvivin therapies reported to date in light of emerging roles for survivin in normal physiology, particularly hematopoiesis, angiogenesis, and immune function.

Downregulation of survivin expression enhances sensitivity of cultured uveal melanoma cells to cisplatin treatment

The purpose of this study is to evaluate the effect of a novel anti-apoptotic gene, survivin, on the resistance and susceptibility of human uveal melanoma cells to apoptosis induced by cisplatin. The sensitivity of human uveal melanoma cell lines to apoptosis induced by cisplatin was analyzed by caspase-3 assays. The expression of the anti-apoptotic protein, survivin, was examined by flow cytometry. Melanoma cells were transfected with either survivin cDNA or survivin anti-sense cDNA and examined for susceptibility to cisplatin-induced apoptosis. Six human uveal melanoma cell lines were incubated with or without cisplatin and cellular proliferation was determined by MTT assays. Significant growth inhibition was observed in 3 melanoma cell lines (OMM1, OCM3, and MEL 270). By contrast, 3 cell lines (OMM2.5, OMM2.3, and 92-1) were resistant to cisplatin-induced apoptosis. However, a positive association was observed between resistance to cisplatin-induced apoptosis and high expression of the anti-apoptotic protein, survivin. Up-regulation of survivin by gene transfer enhanced resistance to cisplatin-induced apoptosis, while transfection with survivin anti-sense rendered resistant melanoma cells susceptible to cisplatin. The combination of cisplatin and actinomycin D significantly decreased survivin expression and enhanced the cisplatin-induced apoptosis of uveal melanoma cells in vitro. These data indicate that resistance of some uveal melanoma cells to cisplatin-induced apoptosis is controlled by anti-apoptotic proteins, such as survivin, that are sensitive to actinomycin D treatment.

Proteolytic cleavage of Livin (ML-IAP) in apoptotic melanoma cells potentially mediated by a non-canonical caspase

BACKGROUND

Several inhibitor of apoptosis proteins (IAPs) are cleaved during apoptosis. Studies of the melanoma-associated IAP (ML-IAP) Livin, using recombinant molecules, have implicated both caspases 3/7 and the serine protease Omi/HtrA2 in its proteolytic cleavage.

OBJECTIVE

To characterize the apoptotic cleavage of Livin in melanocytic cells, and evaluate the role of known proteases.

METHODS

We assessed the capacity of a variety of stimuli to induce Livin cleavage in human melanoma cell lines and normal human melanocytes. The role of caspases and Omi was examined using caspase inhibitors and RNAi, respectively. A potential caspase substrate was further examined by site-directed mutagenesis. Deletion mapping was used to identify the cleavage site.

RESULTS

Livin cleavage was observed in multiple human melanoma cell lines in response to a variety of apoptotic stimuli (UVB, 4-TBP, cisplatin, TNF, Bax), and not affected by the addition of various protease inhibitors or RNAi-mediated silencing of Omi/HtrA2. Livin cleavage induced by 4-TBP, but not UVB or cisplatin, was blocked by the pan-caspase inhibitor zVAD-fmk. Mutation of Asp52 to Glu in Livin did not affect cleavage, while either mutation of Asp52 to Ala, deletion of Asp52, or deletion of the adjacent region (residues 53-61) abrogated cleavage.

CONCLUSION

Livin cleavage, induced by multiple apoptotic stimuli in melanoma cells, likely occurs in an Omi-independent fashion at residue 52 within its potential caspase substrate (DHVD52). However, relative insensitivity of the apoptotic cleavage to zVAD-fmk, or Asp52 to Glu mutation, suggests the involvement of a non-canonical caspase.

Bladder cancer diagnosis and recurrence prognosis: Comparison of markers with emphasis on survivin

Expression of the anti-apoptotic protein survivin is hardly detectable or even absent in many differentiated adult tissues, but is upregulated in almost any type of cancer. Furthermore, high survivin mRNA or protein expression generally correlates with an adverse disease course. Both these important features of survivin expression have been investigated for diagnostic and prognostic purposes in many human cancers, including bladder cancer. In this review, the role of survivin in the detection of bladder tumors and the prediction of tumor recurrence in patients with superficial bladder cancer will be discussed and compared to that of other markers/tests. The most promising marker(s) will be outlined. Also, important requirements for a successful implementation of such markers in a hospital setting are discussed. Finally, future directions for the discovery of new diagnostic or prognostic candidate markers will be mentioned.

Activation of dual apoptotic pathways in human melanocytes and protection by survivin

Apoptosis resistance in melanoma is a primary cause of treatment failure. Apoptotic pathways in melanocytes, from which melanoma arises, are poorly characterized. Human melanocytes were susceptible to apoptosis following exposure to UV radiation (UVB, 24-48 hours), 4-tert-butylphenol (4-TBP, 1-4 hours), and cisplatin (24-48 hours). These responses were associated with Bid cleavage, caspase activation (caspases 3, 8, and 9), mitochondrial depolarization and release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor (AIF), but not endonuclease G. The apoptotic responses and AIF release were caspase-independent, as they were not blocked by zVal-Ala-Asp(OMe)-fluoromethyl ketone (zVAD-fmk). While RNA interference-mediated knockdown of AIF protected melanocytes against apoptosis induced by serum withdrawal, apoptotic responses to UVB, cisplatin, and 4-TBP were not compromised by AIF knockdown, even in the presence of zVAD-fmk. Finally, adenoviral-mediated expression of Survivin, an inhibitor of apoptosis expressed in melanoma but not melanocytes, protected melanocytes against UVB-induced apoptosis. Survivin expression in melanocytes partially blocked caspase activation and release of mitochondrial release of AIF, cytochrome c, and Smac induced by UVB. These data indicate that multiple stimuli can activate both caspase-dependent and caspase-independent apoptotic pathways in melanocytes, and that endogenous expression of Survivin in melanoma may contribute to apoptosis resistance by multiple mechanisms.

Induction of melanoma cell apoptosis and inhibition of tumor growth using a cell-permeable Survivin antagonist

The inhibitor of apoptosis gene family member Survivin is highly expressed in most tumors, and appears to be a promising target for cancer therapy. Although a variety of Survivin antagonists have been shown to induce apoptosis in malignant cells, the potential utility of these agents is limited by inefficient delivery and cell impermeability. We generated recombinant fusion proteins containing the TAT protein transduction domain and either wild-type Survivin (TAT-Surv-WT) or a dominant-negative mutant (TAT-Surv-T34A). The TAT-Surv proteins were purified by sequential affinity and ion-exchange chromatography, and at 30 nM concentration demonstrated rapid entry into cells at 30 min. Whereas TAT-Surv-WT had minimal effect on YUSAC2 or WM793 melanoma cells, TAT-Surv-T34A induced cell detachment, DNA fragmentation, caspase-3 activation and mitochondrial release of apoptosis-inducing factor at low microM concentrations. Intraperitoneal (i.p.) injection of mice bearing subcutaneous YUSAC2 xenografts with TAT-Surv-T34A (10 mg/kg) was associated with rapid tumor accumulation at 1 h, and increased tumor cell apoptosis and aberrant nuclei formation in situ. Repeated i.p. injection of TAT-Surv-T34A resulted in a 40-50% reduction in growth and mass of established tumors, compared to those similarly injected with saline buffer or TAT-Surv-WT. These studies demonstrate the feasibility of systemic tumor treatment using a cell-permeable Survivin antagonist.

Apoptosis inhibitor, survivin, in posterior uveal melanoma: comparison among primary tumors, tumors resistant to brachytherapy, tumors with liver metastases, and liver metastases

PURPOSE

To study the expression of survivin, an apoptosis inhibitor protein, in human posterior uveal melanoma.

METHODS

Specimens were divided according to eyes with tumors that were enucleated primarily, those resistant to brachytherapy, eyes from patients with known liver metastases, and liver metastases.

RESULTS

There was only low expression of survivin in uveal melanoma. No difference in survivin positive cell counts per high power field (PCC/HPF) were found among tumors that were enucleated primarily (n = 33), tumors with previous brachytherapy (n = 29), tumors with liver metastases (n = 12) or liver metastases (n = 18). Corresponding counts were 11.8 (+/-14.3), 11.8 (+/-16.8), 7.1 (+/-11.2), and 4.7 (+/-8.8) in the four groups, respectively (p > 0.05). Half of the liver metastases showed no staining for survivin. Twenty patients (24%) had tumor-related death at the end of follow-up.

CONCLUSIONS

Survivin is expressed in posterior uveal melanomas that were treated by enucleation, as well as in tumors that were previously treated with brachytherapy or liver metastases; however, its expression by immunostaining did not seem with correlate with the tumor biological activity.

Prognostic value of Survivin and Livin in nasopharyngeal carcinoma

BACKGROUND AND OBJECTIVES

Survivin and Livin are new members from the family of anti-apoptotic factors. Increased levels of Survivin and Livin have been observed in many malignancies and correlated with poor prognosis. Survivin is expressed almost exclusively in proliferating cells, including various kinds of cancers, but Livin expression is relatively rare in cancer cells. Therefore, the present study examines the expressions of Survivin and Livin in nasopharyngeal carcinoma (NPC) and investigates whether their expression contributes to the prognosis of NPC.

METHODS

We investigated the expression of Survivin and Livin in 80 NPC samples using immunohistochemistry stain and correlated it with the survival of these patients using log-rank test and Cox multifactor regression analysis.

RESULTS

All the patients were followed up at least for 60 months. During the following period, 21 cases developed distant metastasis, 9 cases developed local-regional recurrence, and 5 developed both distant metastasis and local-regional recurrence. Among them, 30 patients died of recurrence of tumor. In addition, the expression of Survivin was related with distant metastasis. Patients with low Survivin expression had better overall survival, disease-free survival and distant metastasis-free survival rates than the group with high Survivin expression (P = .0086, .0097, and .0318, respectively). Cox regression analysis confirmed that high Survivin expression was related to worse prognosis in NPC patients. However Livin expression level was not related with the survival of patients with NPC.

CONCLUSION

NPC expresses high levels of Survivin and Livin, which may play an important role in the oncogenesis and tumor development. Over-expression of Survivin was related with poor prognosis. We suggest that the determination of Survivin expression may provide predictive information on NPC patients.

Regulation of survivin by ErbB2 signaling: therapeutic implications for ErbB2-overexpressing breast cancers

In breast cancer, overexpression of ErbB2 or aberrant regulation of survivin, a member of the inhibitor of apoptosis family, is associated with resistance to chemo/hormone therapy and predicts for a poor clinical outcome. A functional link between the two predictive factors has not been previously shown. Here, using genetic and pharmacologic approaches to block ErbB2 signaling, we show that ErbB2 regulates survivin protein expression in ErbB2-overexpressing breast cancer cells. Selective knockdown of ErbB2 using small interfering RNA markedly reduced survivin protein, resulting in apoptosis of ErbB2-overexpressing breast cancer cell lines such as BT474. Alternatively, inhibition of ErbB2 signaling using lapatinib (GW572016), a reversible small-molecule inhibitor of ErbB1/ErbB2 tyrosine kinases, at pharmacologically relevant concentrations, leads to marked inhibition of survivin protein with subsequent apoptosis. The effect of lapatinib on survivin seems to be predominantly posttranslational, mediated by ubiquitin-proteosome degradation as lactacystin, a proteosome inhibitor, reverses these effects. Furthermore, lapatinib down-regulated the expression of His-tagged survivin, which was under the transcriptional control of a heterologous promoter, providing additional evidence supporting a posttranslational mechanism of regulation. In contrast, trastuzumab and gefitinib failed to down-regulate survivin in ErbB2-overexpressing breast cancer cells. Importantly, the clinical relevance of these findings was illustrated in patients with ErbB2-overexpressing breast cancer whose clinical response to lapatinib was associated with marked inhibition of survivin in their tumors. These findings shed new light on the mechanism by which ErbB2 overexpression protects against apoptotic stimuli in breast cancer and identifies therapeutic interventions to improve clinical outcomes in these aggressive tumors.

Adenovirus-mediated TA-p73β gene transfer increases chemosensitivity of human malignant melanomas

Malignant melanoma is the most aggressive form of skin cancer and has proven to be highly resistant to conventional chemotherapy. Intriguingly, the p53 tumor suppressor, a main mediator of chemoresistance in other tumor types, is rarely mutated in melanoma. However, we have previously shown that anti-apoptotic isoforms of p73 (deltaTA-p73), another member of the p53 family, are overexpressed in metastatic melanomas. DeltaTA-p73 can oppose the pro-apoptotic functions of p53 and full length p73, and thus it could contribute to melanoma chemoresistance. In this study, we use an efficient adenoviral-based gene transfer approach to introduce a transcriptionally active form of p73 (TA-p73beta) in melanoma cells, with the objective of overcoming drug resistance. Interestingly, TA-p73beta significantly sensitized 5 out of 7 aggressive melanoma cell lines to the standard therapeutic agents adriamycin and cisplatin. More importantly, TA-p73beta displayed a synergistic effect in vivo allowing adriamycin or cisplatin to block melanoma cell growth in mouse xenograft models (p < 0.05). In summary, our data show that Ad-mediated TA-p73beta gene expression can markedly sensitize a subset of melanoma cell lines to adriamycin and cisplatin in vitro and in vivo, suggesting a new chemosensitization strategy for malignant melanomas.

Nuclear expression of the antiapoptotic protein survivin in malignant melanoma

BACKGROUND

Expression of the antiapoptotic protein survivin has been demonstrated in some melanocytic lesions and is believed to be required for melanoma cell viability. However, its diagnostic value in differentiating melanomas from nevi has not yet been examined.

METHODS

Tissue microarray blocks were constructed with paraffin-fixed tissue of 19 nevi, 18 dysplastic nevi, 24 malignant melanomas, and 31 metastatic melanomas. Sections were then reacted with three antisurvivin antibodies (two monoclonal and one polyclonal) assessing labeling intensity (absent or weak, and moderate to strong) as well as the percentage of cells labeled (< 25%, > or = 25%).

RESULTS

Of the antibodies evaluated, the polyclonal one was found to be the most sensitive. Nuclear immunoreactivity for survivin (i.e., > or = 25% of cells exhibiting and/or at least moderately intense staining) was seen in a subset of melanomas but not in nevi or dysplastic nevi (P < 0.05).

CONCLUSIONS

Survivin is variably expressed in the cytoplasm in the entire spectrum of melanocytic lesions, with nuclear expression detectable only in melanomas. These data may underscore the importance of nuclear survivin in progression to melanoma and may prove useful in the differential diagnosis of melanoma versus nevus.

Naked DNA immunization as an approach to target the generic tumor antigen survivin induces humoral and cellular immune responses in mice

Survivin, a 16.5 kDa tumor associated antigen, is the smallest member of the inhibitor of apoptosis family that is abundantly expressed during development but essentially absent in normal adult tissues. Interestingly, survivin expression is up-regulated in virtually all types of cancers studied, as well as in vascular endothelial cells during tumor associated angiogenesis. Survivin links apoptosis to cell cycle progression and plays a pivotal role in regulation of cell proliferation. These characteristics make survivin a potentially promising generic target for cancer immunotherapy. Hence, a genetic immunization strategy to induce tumor-specific immune responses against human survivin in a pre-clinical animal model was developed. In initial studies, BALB/c mice were immunized by intramuscular injection with DNA coding for human survivin (pcDNA3.1/hSurv). In addition, a construct encoding a secreted version of survivin (pSecTag2B/hSurv) was designed. A plasmid coding for murine granulocyte-macrophage colony-stimulating factor (GM-CSF) was co-injected in both cases as a molecular adjuvant. Expression of survivin following transfection in mouse cells was corroborated. Humoral responses against human survivin were detected in mice sera using two immunization protocols (injections at 2- or 3-week intervals). The humoral response was markedly improved by secretion of survivin and co-expression of GM-CSF. The predominant antibody subclass detected in responsive mice was IgG2a, suggesting that a Th1-CD4+ cellular response had been induced. Furthermore, DNA immunization with survivin encoding vectors generated an effective CD8+ T cell response measured as an increase of cytotoxic Interferon-gamma (IFN-gamma) secreting CD8+ T cells. In conclusion, intramuscular genetic immunization of mice with human survivin encoding plasmids induced a survivin-specific humoral as well as cellular immune response in recipient mice. Secretion of survivin and co-injection of GM-CSF as a genetic adjuvant appear to be more important in generating an humoral than a cellular immune response.