The loss of NKX3.1 expression in testicular--and prostate--cancers is not caused by promoter hypermethylation

BACKGROUND: Recent studies have demonstrated that the NKX3.1 protein is commonly down-regulated in testicular germ cell tumors (TGCTs) and prostate carcinomas. The homeobox gene NKX3.1 maps to chromosome band 8p21, which is a region frequently lost in prostate cancer, but not in TGCT. Mutations have not been reported in the NKX3.1 sequence, and the gene is hypothesized to be epigenetically inactivated. In the present study we examined the methylation status of the NKX3.1 promoter in relevant primary tumors and cell lines: primary TGCTs (n = 55), intratubular germ cell neoplasias (n = 7), germ cell tumor cell lines (n = 3), primary prostate adenocarcinomas (n = 20), and prostate cancer cell lines (n = 3) by methylation-specific PCR and bisulphite sequencing. RESULTS AND CONCLUSIONS: Down-regulation of NKX3.1 expression was generally not caused by promoter hypermethylation, which was only found in one TGCT. However, other epigenetic mechanisms, such as modulation of chromatin structure or modifications of histones, may explain the lack of NKX3.1 expression, which is seen in most TGCTs and prostate cancer specimens.     

Survivin splice variants regulate the balance between proliferation and cell death

Survivin is an inhibitor of apoptosis protein that also plays critical roles in regulating the cell cycle and mitosis. Its prominent expression in essentially all human malignancies, and low or absent expression in most normal tissues, suggests that it would be an ideal target for cancer-directed therapy. Impeding development of safe and effective survivin antagonists for clinical use is a lack of understanding of the molecular mechanisms by which survivin differentially affects apoptosis and cell division, in normal and malignant cells. We show that the diverse functional roles of survivin can be explained, in part, by its heterodimerization with survivin splice variants in tumor cells. Survivin and survivin-DeltaEx3 interact within the mitochondria where they may inhibit mitochondrial-dependent apoptosis. If the expression of all survivin forms is eliminated by siRNA transfections, cells undergo both apoptosis and defective cell division. Overall, we provide new insights suggesting that targeting specific survivin isoforms, rather than survivin alone, may selectively and effectively destroy tumor cells. These findings are likely to have a significant impact in the design of biologic agents for clinical therapy.     

Survivin an important determinant for prognosis in adult T-cell leukemia: a novel biomarker in practical hemato-oncology

Survivin is a 16.5-kDa protein that belongs to the inhibitor of apoptosis (IAP) family. It is expressed at high levels in the G2/M phase and is rapidly down-regulated after cell-cycle arrest. It was suggested that survivin plays a pivotal role in linking cell death and cell proliferation. Although present during fetal development, survivin disappears in terminally differentiated adult tissues. Its expression is aberrantly enhanced in transformed cell lines, and in all the most common human cancers. Adult T-cell leukemia (ATL), which is abundant with Fas (Apo-1/CD95), has the characteristic feature of high tumor burden, suggesting that ATL cells probably prolong their lives as a result of escape from apoptosis. Survivin is prominently and consistently expressed in all cases of ATL and ATL cell lines. Its mRNA expression levels among the subtypes of ATL and ATL cell lines are characteristic and informative, low in chronic type, low to high in acute type and extremely high in ATL cell lines. In addition, when the survivin mRNA expression is higher, the survival of the patient is shorter. Its overexpression may account for a growth advantage in vivo and subsequently the malignant behavior of ATL. So quantification of survivin mRNA is important for clinical laboratory examinations. Among all of the current clinical tests for survivin mRNA quantification, the real time PCR is desirable. Despite some technological problems of standardization, quantification of survivin mRNA was shown to be a biological marker for clinical stages or minimal residual disease (MRD).     

Nuclear localization of survivin is a positive prognostic factor for survival in advanced non-small-cell lung cancer.

BACKGROUND: Expression of survivin, a member of the inhibitor of apoptosis protein family, is commonly detected in cancers but not in normal differentiated tissues. Survivin is usually localized in the cytoplasm of cancer cells, but nuclear localization has also been described, and we recently reported that survivin is a nuclear-cytoplasmic shuttling protein. PATIENTS AND METHODS: Fifty-three tumor specimens from patients with inoperable non-small-cell lung cancer (NSCLC) (55% stage IIIA, 17% stage IIIB and 28% stage IV) who underwent chemotherapy treatment were evaluated with immunohistochemistry for survivin expression and localization. These two sets of data were processed and tested for correlation with major patient characteristics, response to chemotherapy, and overall and relapse-free survival. RESULTS: Survivin was present only in malignant tissues, and 47/53 (89%) of the specimens were positive. The overall median expression of tumor cells was 40%, and this value was used as a cut-off point for statistical analysis. By dichotomizing the specimens as expressing low or high levels of survivin, a significant association was seen between the expression of survivin and the histology of the tumors (P=0.020), squamous cell carcinoma being the histotype with lower levels of survivin expression. Three patterns of localization were observed: 42% of cases (22/53) showed reactivity confined to the nucleus, 17% (nine of 53) only in the cytoplasm and 30% (16/53) in both the nucleus and the cytoplasm. Interestingly, nuclear survivin levels predicted longer overall and relapse-free survival, in univariate and multivariate analyses. Expression and localization of survivin did not correlate with response to chemotherapy. CONCLUSIONS: Our results indicate that differential localization of survivin may be a prognostic factor for NSCLC. Further studies are warranted.     

survivin在非小细胞肺癌中表达的意义及其与caspase-3、DFF45蛋白之间的相互关系

目的探讨survivin蛋白的表达在非小细胞肺癌(NSCLC)发生、发展方面的作用及其与临床病理特征之间的联系,与caspase3及DFF45表达的相互关系。方法运用免疫组织化学SP法对60例NSCLC、10例淋巴结转移癌、10例正常支气管粘膜上皮石蜡切片组织中survivin、caspase3及DFF45蛋白的表达进行检测。结果NSCLC、淋巴结转移癌中survivin的阳性表达率分别为70%及90%,显著高于正常支气管粘膜上皮的阳性率10%(P<0.01)。survivin在NSCLC中的表达与分化程度(P<0.01)、TNM分期(P<0.05)、淋巴结转移(P<0.05)有关。而与年龄、性别、病理类型无明显相关(P>0.05)。survivin表达与caspase3的表达呈负相关(P<0.01;r=-0.335),而与DFF45的表达却呈正相关(P<0.01;r=0.406)。结论survivin在NSCLC的发生、发展中起重要作用,可作为NSCLC的诊断指标,对NSCLC恶性程度的判断及预后也有一定参考价值。survivin的作用是通过抑制caspase3的表达,从而影响下游凋亡途径而发挥作用的。     

Sensitization for tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by the chemopreventive agent resveratrol

Survivin is a member of the inhibitor of apoptosis proteins that is expressed at high levels in most human cancers and may facilitate evasion from apoptosis and aberrant mitotic progression. Naturally occurring dietary compounds such as resveratrol have gained considerable attention as cancer chemopreventive agents. Here, we discovered a novel function of the chemopreventive agent resveratrol: resveratrol is a potent sensitizer of tumor cells for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis through p53-independent induction of p21 and p21-mediated cell cycle arrest associated with survivin depletion. Concomitant analysis of cell cycle, survivin expression, and apoptosis revealed that resveratrol-induced G(1) arrest was associated with down-regulation of survivin expression and sensitization for TRAIL-induced apoptosis. Accordingly, G(1) arrest using the cell cycle inhibitor mimosine or induced by p21 overexpression reduced survivin expression and sensitized cells for TRAIL treatment. Likewise, resveratrol-mediated cell cycle arrest followed by survivin depletion and sensitization for TRAIL was impaired in p21- deficient cells. Also, down-regulation of survivin using survivin antisense oligonucleotides sensitized cells for TRAIL-induced apoptosis. Importantly, resveratrol sensitized various tumor cell lines, but not normal human fibroblasts, for apoptosis induced by death receptor ligation or anticancer drugs. Thus, this combined sensitizer (resveratrol)/inducer (e.g., TRAIL) strategy may be a novel approach to enhance the efficacy of TRAIL-based therapies in a variety of human cancers.     

Survivin和PTEN蛋白在宫颈鳞状细胞癌中的表达及临床意义

目的：探讨凋亡抑制基因蛋白Survivin与抑癌基因蛋白PTEN在宫颈癌前病变和宫颈鳞状细胞癌组织中的表达及其两者的相关性。方法：选取93例慢性宫颈炎、宫颈糜烂伴鳞化（慢鳞）、宫颈上皮内瘤变（CIN）及宫颈鳞状细胞癌患者，另取10例正常宫颈组织作为对照。应用免疫组化S-P法检测各组宫颈组织中Survivin和PTEN蛋白的表达。结果：（1）从慢鳞-上皮内瘤变-宫颈鳞状细胞癌，Survivin的表达逐渐增强（P〈0．01），而PTEN的表达逐渐减弱（P〈0．01）；（2）Survivin的表达与宫颈癌组织学分级、浸润深度、临床分期有关（P〈0．05），而与年龄无关（P〉0．05）；PTEN蛋白的表达与宫颈癌浸润深度、临床分期有关（P〈0．05），而与年龄、组织学分级无关（P〉0、05）；（3）Survivin与PTEN蛋白的表达在CIN、宫颈鳞状细胞癌组织中的表达呈显著负相关（P〈0．01），而且在宫颈癌中的表达相关性更为密切。结论：Survivin的异常高表达与PTEN的异常低表达参与了宫颈癌的发生、发展，与凋亡抑制和增殖能力增强有关；发生在宫颈癌恶性转化的早期，并且其表达程度可作为预后不良的标志。     

Survivin overexpression correlates with an apoptosis-resistant phenotype in chronic myeloid leukemia cells

Survivin is a member of the inhibitor of apoptosis protein family (IAP) that acts in both inhibition of apoptosis and regulation of the cell cycle. Despite the fact that survivin is overexpressed in almost all human malignancies, its expression is undetectable in most normal adult tissues, which is what makes it a potential target for anticancer interventions. The aim of this work was to investigate whether survivin is involved in resistance to idarubicin (ida), a drug commonly used in leukemia treatment. Cytotoxic assays using MTT showed that 1 μM of ida could inhibit 50% of cell viability in K562, a chronic myeloid leukemia cell line. Western blotting analysis revealed that survivin expression was increased in the cell line after treatment with ida 0.5 and 1 μM concentrations, protecting cells from ida-induced apoptosis. However, the highest ida concentrations tested were able to inhibit survivin levels and induce apoptosis in K562 cells, as evaluated by morphology and caspase-3 and -9 activation. These results indicate that survivin expression is involved in ida resistance in K562 leukemic cells. Flow cytometry analysis of the cell cycle showed that ida induced G2/M arrest in these cells and there was a statistically significant positive correlation between survivin expression and the percentage of cells in G2/M phase. This work supports the idea that survivin may contribute to an apoptosis-resistant phenotype by inhibiting ida-induced apoptosis and preventing cells from progressing in the cell cycle.     

Molecular characterization of hiwi,a human member of the piwi gene family whose overexpression is correlated to seminomas

The piwi family genes are highly conserved during evolution and play essential roles in stem cell self-renewal, gametogenesis, and RNA interference in diverse organisms ranging from Drosophila melanogaster and C. elegans to Arabidopsis. Here we report the molecular characterization of hiwi, a human member of the piwi gene family. hiwi maps to the long arm of chromosome 12, band 12q24.33, a genomic region that displays genetic linkage to the development of testicular germ cell tumors of adolescents and adults (TGCTs), i.e., seminomas and nonseminomas. In addition, gain of this chromosomal region has been found in some TGCTs. hiwi encodes a 3.6 kb mRNA that is expressed abundantly in the adult testis. It encodes a highly basic 861-amino-acid protein that shares significant homology throughout its entire length with other members of the PIWI family proteins in Drosophila, C. elegans and mammals. In normal human testes, hiwi is specifically expressed in germline cells, with its expression detectable in spermatocytes and round spermatids during spermatogenesis. No expresssion was observed in testicular tumors of somatic origin, such as Sertoli cell and Leydig cell tumors. Enhanced expression was found in 12 out of 19 sampled testicular seminomas-tumors originating from embryonic germ cells with retention of germ cell phenotype. In contrast, no enhanced expression was detected in 10 nonseminomas-testicular tumors that originate from the same precursor cells as seminomas yet have lost their germ cell characteristics. Finally, no enhanced expression was detected in four spermatocytic seminomas-testicular tumors that most likely originate from germ cells capable of partial meiosis. Thus, hiwi is specifically expressed in both normal and malignant spermatogenic cells in a maturation stage-dependent pattern, in which it might function in germ cell proliferation.     

Survivin与VEGF在膀胱癌组织中的表达及Survivin ASODN对膀胱癌细胞系的作用

目的检测膀胱癌组织中Survivin、VEGF表达的相关性;观察Survivin反义寡核苷酸（ASODN）对人膀胱癌的作用研究。方法采用免疫组化和蛋白印迹技术,检测41例膀胱癌组织及癌旁非癌组织中Sur-vivin和VEGF的表达;应用SurvivinASODN作用后收集各组细胞。观察细胞形态变化及超微结果变化,检测各组Survivin表达情况、AI和PI及ASODN对细胞的生长抑制率。结果41例患者中29例（67.4%）表达Survivin蛋白,其中25例（61.0%）VEGF表达阳性或弱阳性;在癌周非癌组织中未检测到Survivin蛋白的表达。Survivin与膀胱癌的转移有关,P=0.002;Survivin蛋白的表达与VEGF蛋白的表达有相关性,P=0.001。电镜下ASODN组可见典型凋亡样改变;各ASODN转染组细胞Survivin表达减弱,呈时间与剂量依赖性;ASODN转染组AI和PI与对照组相比差异有统计学意义,P=0.012,而AI和PI在各对照组间差异无统计学意义,P〉0.05。结论Survivin在膀胱癌组织中的表达能促进膀胱癌的发生与发展,并可能通过上调VEGF的表达而促进膀胱癌发展与转移。Survivin ASODN转染后能下调Survivin蛋白表达,诱导癌细胞凋亡,抑制癌细胞增殖。     

存活素siRNA表达质粒的构建及其对MCF-7细胞细胞周期和增殖的调控

背景与目的：存活素特异地在肿瘤组织中过表达,许多报道表明抑制它的功能对肿瘤治疗有利。RNA干扰被证明是一项能有效而特异地抑制基因表达的新技术。本研究的目的在于构建存活素基因的小分子干扰RNA(siRNA)表达质粒,并检测该质粒在乳腺癌细胞中的生物学功能。方法：应用含有u6启动子的mu6pro载体构建存活素siRNA质粒,RT-PCR和Western blot法检测该质粒转染MCF-7细胞后存活素表达的变化,流式细胞仪和MTT法分别检测其对细胞周期和对细胞增殖的影响。结果：存活素siRNA质粒明显下调MCF-7细胞中存活素的表达,阻断细胞周期在G1期,显著抑制细胞增殖,促进细胞凋亡。结论：通过RNA干扰,存活素的表达在mRNA和蛋白质水平上被下调。     

乳腺癌组织Survivin表达与细胞增殖的关系

目的:探讨乳腺癌组织中Survivin表达的临床病理学意义及其与癌细胞增殖的关系.方法:应用免疫组织化学SP法检测Survivin、Ki-67蛋白在96例乳腺癌组织中及20例正常乳腺组织的表达,分析Survivin 表达与Ki-67增殖指数及各临床病理因素的关系.结果:Survivin阳性表达乳腺癌的Ki-67增殖指数(35.32±21.28%)明显高于Survivin阴性者(20.42±11.34%),Survivin表达与肿瘤细胞增殖呈正相关(P<0.01);Survivin在乳腺癌组织中的表达率为70.83%(68/96),正常乳腺组织未见Survivin表达;Survivin蛋白的表达与临床分期、淋巴结转移和5年生存率有关(P<0.05),与年龄、是否绝经、肿瘤大小和组织学分级均无关.结论: Survivin不仅参与凋亡的调控,还促进细胞增殖. Survivin蛋白在乳腺癌中表达上调,提示其通过抑制凋亡在乳腺癌发生、发展中起重要作用,过度表达提示预后不良.     

RNA干扰survivin基因对卵巢癌细胞生长凋亡及药物敏感性的影响

目的 探讨下调survivin基因对卵巢癌顺铂(DDP)耐药细胞株SKOV3/DDP细胞生长、凋亡及药物敏感性的影响.方法 构建survivin基因的小干扰RNA(siRNA)表达载体pSilencer-survivin,用脂质体方法转染SKOV3/DDP细胞株,另设未转染组和转染pSilencer-control组作为对照.显微镜下观察转染前后细胞的变化,逆转录聚合酶链反应(RT-PCR)和Western blot分别检测survivinmRNA及蛋白的表达,二苯基溴化四氮唑蓝(MTT)法检测细胞生长情况,流式细胞仪检测细胞凋亡及周期的变化.各组细胞加入DDP,检测其对DDP药物敏感性的影响.结果 survivin siRNA可明显下调SKOV3/DDP细胞中survivin mRNA及蛋白表达水平.SKOV3/DDP细胞生长受到明显抑制,生长曲线低平.转染48 h后,转染pSilencer-survivin组细胞凋亡率为19.1%,明显高于末转染组(2.6%)和转染pSilencer-control组(3.5%),G1/G0期细胞所占的比例增高,而G2/M期细胞所占的比例降低.转染pSilencer-survivin组细胞的IC50明显降低,为1.16 μg/mi.结论 survivin siRNA可下调SKOV3/DDP细胞中survivin的表达,使细胞生长减慢,凋亡增加,对DDP的药物敏感性增强.