Expression of survivin in astrocytic tumors: correlation with malignant grade and prognosis

Survivin enhances radiation resistance in primary human glioblastoma cells via caspase-independent mechanisms

The observed radioresistance of human glioblastoma multiforme (GBM) poses a major challenge, which, if overcome, may lead to significant advances in the management of this patient population. There is accumulating evidence from correlative studies that Survivin expression is associated with increased malignant potential of human gliomas. The purpose of this study was to investigate whether Survivin plays a direct role in mediating radiation resistance in primary human glioma cell lines, and, if so, investigating the underlying mechanisms. Our panel of GBM cell lines included two that were relatively radiation resistant (GM20 and GM21) and two that were more radiation sensitive (GM22 and GM23), which demonstrated differential levels of Survivin expression between the two groups. Through the use of adenoviral vectors containing either dominant-negative (pAd-S(T34A)) or wild-type Suvrivin (pAd-S(WT)), we were able to inactivate or overexpress Survivin, respectively. Our findings suggest that Survivin plays a critical role in mediating radiation resistance in primary GBM cells, in part through suppression of apoptotic cell death via a caspase-independent manner. We have identified novel mechanisms by which Survivin may enhance tumor cell survival upon radiation exposure such as regulation of double-strand DNA break repair and tumor cell metabolism, which were most evident in the radiation-resistant cell lines. These differences in Survivin function both in radiation-resistant vs radiation-sensitive cell lines and in the presence vs absence of radiation exposure warrant further investigation and highlight potentially important mechanisms of radiation resistance in these tumors.

Survivin is an independent prognostic marker for risk stratification of breast cancer patients

BACKGROUND

Results in previous qualitative studies of the association of the apoptosis inhibitor survivin with prognosis of breast cancer patients have been contradictory.

METHODS

Survivin mRNA was measured by quantitative TaqMan reverse transcription-PCR in 275 breast cancer tissues from patients with operable tumors and was correlated with established clinicopathologic factors, relapse-free survival [(RFS); 102 events], and overall survival [(OS); 81 events].

RESULTS

High survivin mRNA concentrations were found mainly in tissues from younger patients and in high-grade cancer tissues. High survivin concentrations were most strongly associated with estrogen receptor- or progesterone receptor-negative tumors. In univariate Cox regression analysis for RFS, survivin concentrations were significantly associated with poor prognosis with a hazard ratio (HR) of 1.99 (95% confidence interval, 1.31-3.02; P = 0.001) for every 10-fold increase in expression. For OS, a significant contribution of survivin to poor prognosis was found with a HR of 2.76 (1.67-4.55; P <0.001). Multivariate analyses were performed including established clinicopathologic factors. For RFS, age (P = 0.027), nodal category (P <0.001), and survivin [HR = 1.78 (1.18-2.68); P = 0.006] contributed significantly to the model. For OS, only nodal category (P <0.001) and survivin [HR = 3.05 (1.83-5.10); P <0.001] were significant.

CONCLUSION

Survivin demonstrates a strong, independent, association with poor prognosis. Survivin might be used as a new marker to stratify breast cancer patients for more optimal treatment modalities, or it could be a promising new target for therapy.

Ca2+ homeostasis and apoptotic resistance of neuroendocrine-differentiated prostate cancer cells

Neuroendocrine (NE) differentiation is a hallmark of advanced, androgen-independent prostate cancer, for which there is no successful therapy. NE tumor cells are nonproliferating and escape apoptotic cell death; therefore, an understanding of the apoptotic status of the NE phenotype is imperative for the development of new therapies for prostate cancer. Here, we report for the first time on alterations in intracellular Ca(2+) homeostasis, which is a key factor in apoptosis, caused by NE differentiation of androgen-dependent prostate cancer epithelial cells. NE-differentiating regimens, either cAMP elevation or androgen deprivation, resulted in a reduced endoplasmic reticulum Ca(2+)-store content due to both SERCA 2b Ca(2+) ATPase and luminal Ca(2+) binding/storage chaperone calreticulin underexpression, and to a downregulated store-operated Ca(2+) current. NE-differentiated cells showed enhanced resistance to thapsigargin- and TNF-alpha-induced apoptosis, unrelated to antiapoptotic Bcl-2 protein overexpression. Our results suggest that targeting the key players determining Ca(2+) homeostasis in an attempt to enhance the proapoptotic potential of malignant cells may prove to be a useful strategy in the treatment of advanced prostate cancer.

Expression of survivin and X chromosome-linked inhibitor of apoptosis protein in ameloblastomas

To clarify the role of apoptosis in oncogenesis and cytodifferentiation of odontogenic epithelium, expression of survivin and X chromosome-linked inhibitor of apoptosis protein (XIAP), inhibitor of apoptosis protein (IAP) family proteins, was examined in tooth germs and in benign and malignant ameloblastomas by means of immunohistochemistry and reverse-transcription polymerase chain reaction. Immunoreactivity for survivin and XIAP was detected in developing and neoplastic odontogenic epithelium. In tooth germs, survivin expression was evident in inner enamel epithelium. Follicular, plexiform and metastasizing ameloblastomas showed survivin reactivity chiefly in neoplastic cells neighboring the basement membrane, and most neoplastic cells in basal cell and desmoplastic ameloblastomas and ameloblastic carcinomas were positive for survivin. Survivin mRNA levels were slightly higher in ameloblastomas than in tooth germs, suggesting that elevation of survivin expression might be involved in oncogenesis of odontogenic epithelium. Immunoreactivity for XIAP was detected in most odontogenic epithelial cells in tooth germs and in benign and malignant ameloblastomas, and XIAP mRNA levels were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. The expression of survivin and XIAP in odontogenic tissues suggests that these IAP family proteins contribute to the biological properties of ameloblastomas, such as cell survival, proliferation, differentiation and tissue structuring, as well as to cellular regulation during tooth development.

Nuclear expression of Survivin in paediatric ependymomas and choroid plexus tumours correlates with morphologic tumour grade

Survivin is a gene that is widely expressed throughout the development of the normal mammalian embryo. Subcellular localisation of Survivin to both the nucleus and cytoplasm has suggested multiple functional roles, including inhibition of cell death, especially as demonstrated within a variety of malignant cell types, as well as regulation of the mitotic spindle checkpoint. The expression of Survivin has been associated with an adverse clinical outcome in a large number of malignancies. However, nuclear Survivin expression has been described as an independent variable of favourable prognosis in two large clinical studies of breast and gastric carcinomas. Reports of Survivin expression in normal postnatal, differentiated tissues have been restricted to cell types with high proliferative capacities, including vascular endothelium, endometrium, colonic epithelium, and activated lymphocytes. Prior to this report, expression within the normal human brain had not been characterised. Here, we analyse the expression of Survivin in human brain sections obtained from perinatal and paediatric autopsy cases. We report a strikingly high level of expression of Survivin within normal ependyma and choroid plexus (CP). Analysis of corresponding neoplastic tissue in paediatric ependymomas and CP tumours shows that expression of the nuclear form of Survivin correlates with morphologic tumour grade, with a loss of nuclear expression associated with progressive cytologic anaplasia. This pattern of expression supports a hypothesis that Survivin plays a functional role in normal ependymal growth and/or neural stem cell differentiation, and that abnormally low levels of expression of the nuclear form of this protein may be a marker of more aggressive disease and/or higher morphologic grade in ependymal and CP tumours.

Survivin, versatile modulation of cell division and apoptosis in cancer

Survivin is a member of the inhibitor of apoptosis (IAP) gene family that has attracted attention from several viewpoints of basic and translational research. Its cell cycle-regulated expression at mitosis and association with the mitotic apparatus have been of interest to cell biologists studying faithful segregation of sister chromatids and timely separation of daughter cells. Investigators interested in mechanisms of apoptosis have found survivin an evolving challenge: while survivin inhibits apoptosis in vitro and in vivo, this pathway may be more selective as compared to cytoprotection mediated by other IAPs. Finally, basic and translational researchers in cancer biology have converged on survivin as a pivotal cancer gene, not simply for its sharp expression in tumors and not in normal tissues, but also for the potential exploitation of this pathway in cancer diagnosis and therapy. The objective of the present contribution is to line up current evidence and emerging concepts on the multifaceted functions of survivin in cell death and cell division, and how this pathway is being pursued for novel cancer therapeutic strategies.

Survivin study: what is the next wave?

Survivin, a novel member of inhibitor of apoptosis (IAP) protein family, is aberrantly expressed in cancer but undetectable in normal, differentiated adult tissues. Current studies suggest that survivin is implicated in both control of apoptosis and regulation of cell division. However, due to some inconsistent observations on survivin subcellular localization, there is debate about survivin's function in regulating apoptosis, cell division, or both. This review will discuss concepts, experimental methods, and interesting results that unify the different notions about survivin localization and function or point out gaps of knowledge about controversial issues. The author also intends to review various aspects of survivin studies, which were not emphasized or sufficiently discussed in previous reviews on survivin, and update recent developments that may reveal new applications of disease-oriented therapeutics in the coming years.