Prognostic significance of survivin expression in renal cell cancer and its correlation with radioresistance

Survivin, an important inhibitor of apoptosis, has been found to play an important role in the initiation, progression, and chemoradioresistance of human malignancies. Previously, we have reported that upregulation of survivin in oral squamous cell carcinoma correlates with poor prognosis and chemoresistance. The aim of this study was to assess prognostic significance of survivin protein expression in RCC and analyze its correlation with radiosensitivity of RCC cells. RT-PCR and Western blot assays were performed to detect survivin mRNA and protein expression in normal human kidney epithelial cell line (HKEC) or RCC cell lines. The expression of survivin mRNA in RCC and corresponding nontumor kidney tissues was also detected by RT-PCR. Immunohistochemistry was performed to determine survivin protein expression in 75 cases of RCC tissue samples. Moreover, the association of survivin protein expression with clinicopathogical factors and prognosis of RCC patients was statistically analyzed. Small interfering RNA was used to knockdown the endogenous survivin expression in RCC cell line (ACHN) and evaluate the effects of survivin knockdown on proliferation, apoptosis, and radiosensitivity of RCC cell line. RCC cells showed sufficient expression of survivin mRNA and protein, but the expression of survivin gene was not detected in normal HKEC. Moreover, the expression level of survivin mRNA in RCC tissues was significantly higher than that in corresponding nontumor kidney tissues. The immunostaining of survivin protein was mainly located in cytoplasm of RCC tumor cells. Tumor pathological stage (P = 0.028), grade (P = 0.004), and lymph node metastasis (P = 0.017) of RCC patients were significantly correlated with survivin protein expression. In addition, patients with high survivin levels had a significantly shorter overall survival than those with low levels (P < 0.001), and the expression of survivin protein was an independent prognostic factor for RCC patients (P = 0.008). The expression of survivin gene could be reduced in RCC cell line and survivin knockdown could inhibit growth and enhance in vivo radiosensitivity of RCC cell line by inducing apoptosis enhancement. Taken together, the status of survivin protein expression may be an independent factor for predicting the prognosis of RCC patients and tumor-specific survivin knockdown combined with radiotherapy will be a potential strategy for RCC therapy.     

Hsp60 regulation of tumor cell apoptosis

Molecular chaperones may promote cell survival, but how this process is regulated, especially in cancer, is not well understood. Using high throughput proteomics screening, we identified the cell cycle regulator and apoptosis inhibitor survivin as a novel protein associated with the molecular chaperone Hsp60. Acute ablation of Hsp60 by small interfering RNA destabilizes the mitochondrial pool of survivin, induces mitochondrial dysfunction, and activates caspase-dependent apoptosis. This response involves disruption of an Hsp60-p53 complex, which results in p53 stabilization, increased expression of pro-apoptotic Bax, and Bax-dependent apoptosis. In vivo, Hsp60 is abundantly expressed in primary human tumors, as compared with matched normal tissues, and small interfering RNA ablation of Hsp60 in normal cells is well tolerated and does not cause apoptosis. Therefore, Hsp60 orchestrates a broad cell survival program centered on stabilization of mitochondrial survivin and restraining of p53 function, and this process is selectively exploited in cancer. Hsp60 inhibitors may function as attractive anticancer agents by differentially inducing apoptosis in tumor cells.     

Inhibitors of apoptosis proteins (IAPs) as potential molecular targets for therapy of hematological malignancies

Apoptosis, a programmed cell death, plays a key role in the regulation of tissue homeostasis. However, impairment of its regulation may promote formation and progression of malignancy. An important part of the apoptotic machinery are the inhibitor of apoptosis protein (IAP) family, regulating caspase activity, cell division or cell survival pathways through binding to their baculovirus AIP repeat (BIR) domains and/or by their ubiquitin-ligase RING zinc finger (RZF) activity. The following IAPs have been described so far: NAIP (neuronal apoptosis inhibitory protein; BIRC1), cIAP1 and cIAP2 (cellular inhibitor of apoptosis 1 and 2; BIRC2 and BIRC3, respectively), XIAP (X-chromosome binding IAP; BIRC4), survivin (BIRC5), BRUCE (Apollon; BIRC6), livin (BIRC7) and Ts-IAP (testis-specific IAP; BIRC8). Several studies suggested a potential contribution of IAPs to oncogenesis and resistance to anti-tumor treatment. Increased IAP expression was found in variety of human cancers, including hematological malignancies, such as leukemias and B-cell lymphomas. A correlation between the progression of those diseases and high levels of survivin or XIAP has been reported. Overexpression of XIAP in acute myeloid leukemia or survivin in acute lymphoblastic leukemia and diffuse large B-cell lymphoma have been indicated as an unfavorable prognostic factors. Elevated cellular levels of cIAP1, cIAP2, XIAP and survivin correlated with a progressive course of chronic lymphocytic leukemia. Thus, targeting IAPs with small-molecule inhibitors by their antisense approaches or natural IAP antagonist mimetics, may be an attractive strategy of anti-cancer treatment. Such agents can either directly induce apoptosis of tumor cells or sensitize them to other cytotoxic agents, hence overcoming drug-resistance. This review demonstrates the current knowledge on IAP molecular biology, as well as the mechanisms of action and the development of IAP-targeting agents for treatment of hematological malignancies.     

Nuclear survivin promoted by acetylation is associated with the aggressive phenotype of oral squamous cell carcinoma

Defects in apoptotic pathway contribute to development and progression of oral cancer. Survivin, a member of the inhibitors of apoptosis protein (IAP) family, is increased in many types of cancers. However, it is unclear whether increased survivin is associated with oral squamous cell carcinomas (OSCC), and what mechanisms may involve in. In this study, we examined survivin expression in OSCC compared with normal oral tissues via immunohistochemical staining. The results showed that, not only total survivin is increased in OSCCs, but also the subcellular location of survivin is changed in OSCCs compared with normal oral tissues. In most of normal oral tissues, survivin staining was either negative, or cytoplasmic positive/nuclear negative; whereas in most of OSCC tissues, survivin staining was nuclear positive. Statistic analysis indicates that nuclear survivin, rather than total or cytoplasmic one, correlates with tumor TNM stage and differentiation grade. Consistently, in vitro analysis showed that survivin is in cytoplasm in normal human oral kinotinocyte (HOK) cells; whereas it is in nucleus in OSCC HN6 cells. Importantly, treatment of HOK cells with HDAC inhibitor Trichostatin A (TSA) induces survivin acetylation and promotes its nuclear localization. Moreover, nuclear survivin in OSCC cells was acetylated at K129 in its C-terminal, suggesting that the acetylation is important for nuclear location of survivin. Our study demonstrates that it is nuclear survivin, rather than total or cytoplasmic one, associates with TNM stage and tumor grade of OSCC. Thus, we propose nuclear survivin as a prognostic marker for the progression of OSCC.     

Scutellarin inhibits the glioma cell proliferation by downregulating BIRC5 to promote cell apoptosis

The expression changes of baculovirus inhibitor of apoptosis repeat-containing protein5 in brain glioma after administration of Scutellarin was detected. To explore the effort of scutellarin on anti-glioma by downregulating BIRC5.The effect of scutellarin on tumour growth and animal survival was detected by administering scutellarin to nude mice subcutaneous tumour formation and SD rats in situ tumour formation models. A significantly different gene BIRC5 was found by using the combination of TCGA databases and network pharmacology. And then qPCR was performed to detect the expression of BIRC5 in glioma tissues, cells and normal brain tissues and glial cells. CCK-8 was used to detect the IC50 of scutellarin on glioma cells. The wound healing assay, flow cytometry and MTT test were used to detect the effect of scutellarin on the apoptosis and proliferation of glioma cells. The expression of BIRC5 in glioma tissues was significantly higher than that in normal brain tissues. Scutellarin can significantly reduce tumour growth and improve animal's survival. After scutellarin was administered, the expression of BIRC5 in U251 cells was significantly reduced. And after same time, apoptosis increased and cell proliferation was inhibited. This original research showed that scutellarin can promote the apoptosis of glioma cells and inhibit the proliferation by downregulating the expression of BIRC5.     

肿瘤中与survivin有关的信号通路及分子以及靶向survivin的治疗前景

Survivin在细胞内环境稳定和肿瘤的形成中起重要的作用,在肿瘤的治疗中,survivivin的靶向治疗调节与一些典型的信号通路和一系列生长因子有关。众所周知,survivin是一个小的凋亡蛋白抑制因子,也是一个主要的抗癌靶标,与细胞分裂和凋亡抑制有关,它在大部分正常组织中缺失但在大部分癌组织中过表达。Survivin是一个与众多细胞信号通路有关的节点蛋白,这些通路协调各种细胞因子、转录网络和修饰基因,通过调节癌细胞内环境稳定直接或间接促进细胞增殖。临床前研究数据表明,survivin的抑制可以降低细胞增殖促进凋亡,增加细胞对细胞毒药物和放疗的敏感性,其过表达与不良预后和治疗耐受有关。因此对于癌症治疗,survivin是一个潜在的靶标。     

Antitumor effects of a xenogeneic survivin bone marrow derived dendritic cell vaccine against murine GL261 gliomas

Survivin is a member of the inhibitor of apoptosis protein family. Gliomas and many other tumors express survivin at high levels; whereas, normal fully differentiated cells generally do not. Therefore, survivin represents a tumor-specific target for cancer vaccine therapy. It has been shown that it is possible to produce a MHC-I-restricted cellular immunologic response to survivin vaccines. To study differences in immunogenicity between murine and human survivin proteins, we vaccinated C57BL/6 mice with bone marrow dendritic cells (BMDC) transfected with expression vectors containing the murine and human survivin genes. Mice vaccinated with BMDCs expressing a truncated human survivin protein developed cytotoxic T lymphocyte to subcutaneous GL261 glioma cells and exhibited prolonged tumor-free survival compared to mice vaccinated with BMDCs transfected with vector alone (P<0.01). While mice challenged with intracerebral GL261 cells had increased survival, no cures were observed. In contrast, vaccinated mice that fully resisted subcutaneous tumor challenge were rendered resistant to intracerebral GL261 re-challenge. BMDCs transfected with the full-length human survivin molecule were significantly more effective at prolonging survival than BMDCs expressing the full-length murine survivin gene (P=0.0175). Therefore, xenogeneic differences between human and murine sequences might be exploited to develop more immunogenic tumor vaccines.     

Apoptosis-related gene expression in glioblastoma (LN-18) and medulloblastoma (Daoy) cell lines

The expression of apoptosis genes in a commercial pre-designed low-density array from Applied Biosystems was evaluated in two human brain cancer cell models, LN-18 and Daoy (HTB-186?) in comparison to the reference human primary endothelial cells under basic conditions. Analysis of the gene expression in the cancer cell lines compared to the normal control revealed features reflecting anti-apoptotic and inflammatory characteristics of the former. There was an overall downregulation of apoptosis-stimulating genes in both cancer cell lines, along with an upregulation of certain apoptosis inhibitors. A number of genes demonstrated statistically significant changes in their expressions, including BAX (BCL2-associated X protein); the CARD4/NLR family, CARD domain containing 4; CASP10 (caspase 10, apoptosis-related cysteine peptidase); DAP1 (death-associated protein kinase 1), and BIRC5 (baculoviral IAP repeat-containing 5). Anti-apoptotic potential in both cell lines was demonstrated by changes in the Bax:Bcl-2 ratio and downregulation of the APAF1 gene in LN18 cells. There was also significant downregulation of extrinsic signals and the TNF/FADD/inflammatory cascade, and upregulation of caspase inhibitors (IAPs). These results provided a novel molecular characterization of important human cancer cell lines, which might provide a useful research tool for investigating the experimental model of the CNS cell.     

Polo-like kinase and survivin are esophageal tumor-specific promoters

For developing successful cancer gene therapy strategies, tumor-specific gene delivery is essential. In this study, we used esophageal cancer (EC) cells to identify and evaluate esophageal tumor-specific gene promoters. Four genes (polo-like kinase-1/PLK, survivin/BIRC5, karyopherin alpha 2/KPNA2, and pituitary tumor transforming gene protein 1/PTTG1) were identified by a microarray analysis as highly expressed in EC cell lines vs. five normal organ tissues (liver, lung, kidney, brain, and heart). By quantitative RT-PCR, the average mRNA expression levels of these four genes in 20 primary ECs were 2.7-fold (PLK), 6.1-fold (survivin), 2.6-fold (KPNA2), and 2.4-fold (PTTG1) higher than that of each gene in 24 different normal organs. By dual luciferase assay, the promoter activity of PLK and survivin in EC cell lines was 18.9-fold and 28.5-fold higher, respectively, than in normal lung and renal cells. The promoters of PLK and survivin could be useful tools for developing EC-specific gene therapy vectors.     

Inhibition of CDK1 as a potential therapy for tumors over-expressing MYC

Tumor cells have a dysregulated cell cycle that may render their proliferation especially sensitive to the inhibition of cyclin-dependent kinases (CDKs), important regulators of cell cycle progression. We examined the effects of CDK1 inhibition in the context of different oncogenic signals. Cells transformed with MYC, but not cells transformed by a panel of other activated oncogenes, rapidly underwent apoptosis when treated with small-molecule CDK1 inhibitors. The inhibitor of apoptosis protein BIRC5 (survivin), a known CDK1 target, is required for the survival of cells overexpressing MYC. Inhibition of CDK1 rapidly downregulates survivin expression and induces MYC-dependent apoptosis. CDK1 inhibitor treatment of MYC-dependent mouse lymphoma and hepatoblastoma tumors decreased tumor growth and prolonged their survival. As there are no effective small-molecule inhibitors that selectively target the MYC pathway, we propose that CDK1 inhibition might therefore be useful in the treatment of human malignancies that overexpress MYC.     

Down-regulation of survivin in nitric oxide-induced cell growth inhibition and apoptosis of the human lung carcinoma cells

Survivin is expressed in most tumor cells and has been associated with both anti-apoptosis and mitotic progression. However, the mechanism of regulation of the survivin expression remains unclear. In this study we investigated the expression and regulation of survivin in the nitric oxide (NO)-exposed human lung carcinoma cells. The lung carcinoma cell lines CL3, H1299, and A549 but not normal lung fibroblast expressed high levels of survivin proteins. NO donors S-nitroso-N-acetyl-penicillamine (SNAP) and sodium nitroprusside (SNP) decreased the survivin expression. SNAP (0.4 mm, 24h)and SNP (1 mm, 24 h) significantly induced cytotoxicity and apoptosis in lung carcinoma cells. Furthermore, SNAP inhibited the cell growth and increased the fractions of G(2)/M phase. The levels of cyclin B1 and phospho-cdc2-(Thr-161) proteins were inhibited in the NO-exposed cells. The cdc25 phosphatase inhibitors (Cpd 5 and NSC 663284) and the cdc2 kinase inhibitors (alsterpaullone and purvalanol A) enhanced SNP-induced cytotoxicity and the decrease in survivin expression. However, overexpression of survivin by a pOTB7-survivin vector reduced SNP-induced cell growth inhibition and cytotoxicity. In addition, SNP activated the phosphorylation of p38 mitogen-activated protein (MAP) kinase. The specific p38 MAP kinase inhibitor, SB202190, significantly decreased the cytotoxicity and increased the survivin levels in NO donor-treated and inducible NOS-transfected cells. Conversely, anticancer agents including quercetin, arsenite, and cisplatin but not genistein increased the levels of survivin protein. Our results indicated for the first time that NO inhibited the expression of survivin, which was down-regulated by the p38 MAP kinase pathway.     

X连锁凋亡抑制蛋白的功能及其在肿瘤中的作用

X连锁凋亡抑制蛋白(X-linked inhibitor of apoptosis,XIAP)是目前发现的最具特征性与作用最强的内源性凋亡抑制蛋白质.XIAP特征性结构是其BIR结构域和RING结构域,它们都是XIAP发挥抗凋亡作用的重要结构.多种内源性抑制蛋白质(XAF1、Smac和Omi)能通过不同的方式抑制XIA...     

Arf6, RalA and BIRC5 protein expression in non small cell lung cancer

Evaluation of tumor markers expression pattern which determines individual progression parameters is one of the major topics in molecular oncopathology research. This work presents research on expression analysis of several Ras-Ral associated signal transduction pathway proteins (Arf6, RalA and BIRC5) in accordance with clinical criteria in non small cell lung cancer patients. Using Western-blot analysis and RT-PCR Arf6, RalA and BIRC5 expression has been analyzed in parallel in 53 non small cell lung cancer samples of different origin. Arf6 protein expression was elevated in 55% non small cell lung cancer tumor samples in comparison with normal tissue. In the group of squamous cell lung cancer Arf6 expression elevation was observed more often. RalA protein expression was decreased in comparison to normal tissue samples in 64% of non small cell lung cancer regardless to morphological structure. Correlation between RalA protein expression decrease and absence of regional metastases was revealed for squamous cell lung cancer. BIRC5 protein expression in tumor samples versus corresponding normal tissue was 1.3 times more often elevated in the squamous cell lung cancer group (in 76% tumor samples). At the same time elevation of BIRC5 expression was fixed only in 63% of adenocarcinoma tumor samples. A statistically significant decrease (p = 0.0158) of RalA protein expression and increase (p = 0.0498) of Arf6 protein expression in comparison with normal tissue was found for T1-2N0M0 and T1-2N1-2M0 groups of squamous cell lung cancer correspondingly.     

Survivin expression in the stomach: implications for mucosal integrity and protection

Survivin, an apoptosis inhibitor, is highly expressed in a majority of human cancers and is required during embryonic development. Our present studies show that survivin is also expressed in normal gastric mucosa of adult humans and rats. In both human and rat gastric mucosa, survivin is expressed predominantly in the nuclei of mucosal surface epithelial cells. In rats, survivin is also detected in the nuclei of some neck cells, whereas in the humans, survivin is expressed in both nuclei and cytoplasm of chief and parietal cells. Furthermore, survivin is expressed at higher levels in the nuclei of cultured gastric mucosal epithelial cells than in gastric microvascular endothelial cells, which supports the expression pattern in intact tissues. Based on these expression studies, and the known role of survivin as an anti-apoptosis protein, survivin may play a role in maintaining gastric mucosal integrity and regulating cell renewal in the gastric mucosa.     

PML与基因组稳定性

基因组稳定性同肿瘤的发生、发展密切相关,维护基因组稳定性对于细胞行使正常的生理功能是至关重要的.早幼粒细胞白血病蛋白PML(promyelocytic leukemia)主要借助分子中RBCC结构,同近50种有重要功能的蛋白相互作用而形成PML-NBs(PML nuclear bodies).PML-NBs是与核基质结合的、动态的、亚核多蛋白复合物,它作为区室化核结构(compartmentalized nuclear architecture)——染色质间区室(interchromatin compartment)的功能单位,满足了真核基因高层次表达调控模式的时空要求.最新的研究证明：PML是基因组稳定性“守门人”——p53分子的搭档分子,同样在基因组稳定性调控中发挥着重要的功能作用.它协同p53参与了DNA损伤反应所诱发的细胞凋亡,还可组织多种DNA修复分子参与DNA损伤修复,在DNA损伤反应中具有重要作用;此外,PML还通过调控aurora A的活性参与中心体复制检查点调控,借助调控survivin的表达参与有丝分裂纺锤体组装检查点调控,在染色体复制和细胞分裂中均显示了重要的调控作用.而当PML表达缺失或不足时则与多种肿瘤的发生、发展相关联,因此PML分子在维护基因组稳定性中具有重要功能作用,本文仅就相关的最新研究进展予以概述     

Apollon ubiquitinates SMAC and caspase-9, and has an essential cytoprotection function

Apollon (also known as BRUCE or BIRC6) is a large protein containing baculoviral-IAP-repeat (BIR) and ubiquitin-conjugating enzyme (UBC) domains at the amino- and carboxy termini, respectively. Apollon inhibits apoptosis, but its molecular and physiological function remains unclear. Here we report that Apollon binds to, ubiquitinates and facilitates proteasomal degradation of SMAC and caspase-9, which both contain IAP-binding motifs. Targeted disruption of Apollon in mice caused embryonic and neonatal lethality. Notably, SMAC induced apoptosis in Apollon-deficient cells, but not in Apollon-expressing cells. Furthermore, the IAP-binding motif of SMAC was required to induce apoptosis in Apollon-deficient cells. These results suggest that Apollon has an essential function in preventing SMAC-induced apoptosis.     

MageA2 restrains cellular senescence by targeting the function of PMLIV/p53 axis at the PML-NBs

MAGE-A genes are a subfamily of the melanoma antigen genes (MAGEs), whose expression is restricted to tumor cells of different origin and normal tissues of the human germline. Although the specific function of individual MAGE-A proteins is being currently explored, compelling evidence suggest their involvement in the regulation of different pathways during tumor progression. We have previously reported that MageA2 binds histone deacetylase (HDAC)3 and represses p53-dependent apoptosis in response to chemotherapeutic drugs. The promyelocytic leukemia (PML) tumor suppressor is a regulator of p53 acetylation and function in cellular senescence. Here, we demonstrate that MageA2 interferes with p53 acetylation at PML-nuclear bodies (NBs) and with PMLIV-dependent activation of p53. Moreover, a fraction of MageA2 colocalizes with PML-NBs through direct association with PML, and decreases PMLIV sumoylation through an HDAC-dependent mechanism. This reduction in PML post-translational modification promotes defects in PML-NBs formation. Remarkably, we show that in human fibroblasts expressing RasV12 oncogene, MageA2 expression decreases cellular senescence and increases proliferation. These results correlate with a reduction in NBs number and an impaired p53 response. All these data suggest that MageA2, in addition to its anti-apoptotic effect, could have a novel role in the early progression to malignancy by interfering with PML/p53 function, thereby blocking the senescence program, a critical barrier against cell transformation.