cyclinB1、p34cdc2在卵巢上皮性肿瘤中的表达及临床意义

目的探讨细胞周期调控因子cyclinB1、p34cdc2在卵巢肿瘤发生、发展及预后中的作用。方法应用免疫组化SP法对正常卵巢、卵巢良性上皮性肿瘤及恶性肿瘤中cyclinB1、p34cdc2的表达进行检测。结果cy-clinB1和p34cdc2在正常卵巢、良性肿瘤和恶性肿瘤中的阳性表达呈递增趋势,在恶性肿瘤的阳性表达率显著高于正常卵巢和良性肿瘤(P<0.05);并且cyclinB1和p34cdc2的表达与肿瘤的分化程度、临床分期及预后明显相关(P<0.05)。结论cyclinB1和p34cdc2在卵巢肿瘤的进展、诊断和判断预后方面有一定的意义。     

cyclinB1、p34cdc2在卵巢上皮性肿瘤中的表达及临床意义

目的：探讨细胞周期调控因子cyclinB1、p34^cdc2在卵巢肿瘤发生、发展及预后中的作用。方法：应用免疫组化SP法对正常卵巢、卵巢良性上皮性肿瘤及恶性肿瘤中cyclinB1、p34^cdc2的表达进行检测。结果：cyclinB1和p34^cdc2在正常卵巢、良性肿瘤和恶性肿瘤中的阳性表达呈递增趋势，在恶性肿瘤的阳性表达率显著高于正常卵巢和良性肿瘤（P＜0．05）；并且cyclinB1和p34^cdc2的表达与肿瘤的分化程度、临床分期及预后明显相关（P＜0．05）。结论：cyclinB1和p34^cdc2在卵巢肿瘤的进展、诊断和判断预后方面有一定的意义。     

p27和CyclinE在卵巢上皮性肿瘤中的表达及其临床意义

目的 :研究p2 7、CyclinE与卵巢上皮性肿瘤发生及发展的关系。方法 :采用SP免疫组织化学方法检测了 4 0例卵巢恶性上皮肿瘤、6例交界性肿瘤及 18例良性肿瘤中p2 7、CyclinE蛋白的表达情况。结果 :p2 7和CyclinE在良性肿瘤与交界性肿瘤中表达差异无显著意义。p2 7在恶性肿瘤中的表达率 (35 0 % )显著低于交界性肿瘤和良性肿瘤表达率 (77 78%、4 6 ) ,P <0 0 1;CyclinE在卵巢上皮恶性肿瘤中的表达率显著高于良性肿瘤及交界性肿瘤 ,P <0 0 1。p2 7和CyclinE蛋白表达与卵巢癌的临床分期、病理分级、淋巴结转移有关。p2 7阴性 CyclinE阳性者 ,其生物学行为极差。结论 :p2 7、CyclinE与卵巢癌的发生及发展密切相关 ,其异常表达提示卵巢肿瘤预后差     

磷脂酰肌醇3激酶-蛋白质丝氨酸苏氨酸激酶途径与肿瘤的关系

磷脂酰肌醇3激酶(PI3K)-蛋白质丝氨酸苏氨酸激酶(Akt)途径是细胞内重要的信号传导途径,在细胞增殖分化中起重要作用。PI3K-Akt途径的失调控对于多种肿瘤的发生是一种刺激信号,途径中任何激酶表达的异常都可能诱导肿瘤的发生。现综述PI3K-Akt途径中PI3K、Akt、磷脂酰肌醇依赖性蛋白激酶(PDK)、与张力蛋白同源的第10号染色体上丢失的磷酸酶基因 (PTEN)在肿瘤发生发展中的作用。     

磷脂酰肌醇3激酶-蛋白质丝氨酸苏氨酸激酶途径与肿瘤的关系

磷脂酰肌醇3激酶（PI3K）-蛋白质丝氨酸苏氨酸激酶（Akt）途径是细胞内重要的信号传导途径,在细胞增殖分化中起重要作用。PI3K-Akt途径的失调控对于多种肿瘤的发生是一种刺激信号,途径中任何激酶表达的异常都可能诱导肿瘤的发生。现综述PI3K-Akt途径中PI3K、Akt、磷脂酰肌醇依赖性蛋白激酶（PDK）、与张力蛋白同源的第10号染色体上丢失的磷酸酶基因（PTEN）在肿瘤发生发展中的作用。     

卵巢上皮性肿瘤组织中核转录因子E2F3蛋白的表达及其临床意义

目的:通过检测核转录因子E2F3蛋白在卵巢上皮性癌(卵巢癌)、卵巢交界性肿瘤、良性肿瘤和正常卵巢组织中的表达,探讨E2F3在卵巢上皮恶性肿瘤的发病机制中可能起到的作用,并为卵巢癌的早期筛查及基因治疗提供新思路.方法:采用免疫组化SP法检测33例卵巢上皮性癌,11例卵巢交界性肿瘤,13例卵巢良性肿瘤和12例正常卵巢组织中E2F3蛋白的表达,并分析其临床意义.结果:在卵巢癌、卵巢交界性肿瘤、良性肿瘤和正常卵巢组织中,E2F3蛋白的平均光密度值(MOD)分别为0.454±0.053、0.143±0.047、0.124±0.028、0.134±0.040.E2F3蛋白在卵巢癌组中的表达水平明显高于卵巢交界性肿瘤组,其差异具有统计学意义(P<0.01); 而交界性肿瘤、良性肿瘤与正常卵巢三组间相比,差异不具有统计学意义(P>0.05).在卵巢癌组中,E2F3蛋白的表达水平与手术病理分期、病理分级相关(P<0.01;P<0.01).而与淋巴结转移的发生无关(P>0.05).结论:核转录因子E2F3蛋白表达上调多见于卵巢癌组织,其表达水平与手术分期、病理分级相关.E2F3可能通过参与细胞周期调控,在卵巢癌的发生发展中起到促进作用.     

PLK1小分子抑制剂的肿瘤治疗新策略

Polo样激酶1（polo-like kinase 1,PLK1）是一类广泛存在的丝氨酸／苏氨酸蛋白激酶,其结构和功能高度保守。PLK1在肿瘤的发生及发展中起重要作用,使其成为肿瘤治疗的重要靶点。目前,已发现的PLK1小分子抑制剂有几十种,通过不同分子机制抑制PLK1功能,进而产生肿瘤抑制作用。本文针对PLK1小分子抑制剂在肿瘤治疗中的研究进展作一综述。     

TOPK与肿瘤关系的研究进展

TOPK是一个新近发现的丝-苏氨酸蛋白激酶,是一个重要的信号分子.在生理情况下,TOPK仅表达于睾丸和胸腺中,与机体生殖细胞的成熟和免疫细胞激活有关.近年来研究显示,TOPK在多种恶性肿瘤细胞中呈高表达,不仅调控着肿瘤细胞的有丝分裂和细胞周期,并且参与了肿瘤细胞增殖、迁移、侵袭和凋亡过程.关于TOPK与肿瘤关系的研究正日益被人们关注,其特异性阻断剂也已被应用于肿瘤学研究中.     

Pim-2基因与造血系统肿瘤

Pim-2原癌基因属于丝氨酸苏氨酸激酶家族,具有抗凋亡以及在生长因子与细胞因子刺激下维持造血细胞生存、调节造血细胞生长及分化的特性。Pim-2过表达可以协同c-myc基因促进鼠及人类淋巴瘤的形成,深入研究Pim-2基因及其抑制剂可望为造血系统恶性肿瘤的治疗开辟新途径。     

Pim-2基因与造血系统肿瘤

Pim-2原癌基因属于丝氨酸苏氨酸激酶家族,具有抗凋亡以及在生长因子与细胞因子刺激下维持造血细胞生存、调节造血细胞生长及分化的特性。Pim-2过表达可以协同c—myc基因促进鼠及人类淋巴瘤的形成,深入研究Pim-2基因及其抑制剂可望为造血系统恶性肿瘤的治疗开辟新途径。     

Increased expression of p34cdc2 and its kinase activity in human gastric and colonic carcinomas

We examined the expression of p34^cdc2 and its kinase activity in human gastric and colonic carcinoma cell lines and carcinoma tissues and studied its relation with a tumor-suppressor gene product, p53. All the gastric and colonic cancer cell lines expressed p34^cdC2 and showed its kinase activity at various levels. When the cells were arrested in mitotic metaphase by the use of nocodazole, p34^cdC2 kinase activity was induced and p53 was apparently phosphorylated. Of 12 gastric carcinoma cases, 11 (91.7%) showed higher p34^cdC2 kinase activity in tumor tissues than in corresponding non-neoplastic mucosa. The protein kinase activities in the individual cases were well correlated with the levels of p34^cdc2 protein expression. A good correlation was also found between the expression of p34^cdc2 and proliferating cell nuclear antigen (PCNA). Almost all the colonic carcinomas showed higher cdc2 kinase activity and increased p34 expression when compared with non-neoplastic mucosa. Interestingly, most of the gastric and colonic carcinomas having high cdc2 kinase activity expressed high levels of p53. These findings suggest that the increased p34^cdc2 kinase activity might cause the development and proliferation of gastric and colonic carcinomas, partly through abnormal p53 accumulation.     

Inhibition of p34cdc2 kinase activation, p34cdc2 tyrosine dephosphorylation, and mitotic progression in Chinese hamster ovary cells exposed to etoposide.

p34cdc2 kinase, an enzyme essential for mitosis in mammalian cells, may play a role in etoposide-induced G2 phase arrest of Chinese hamster ovary cells. In this study, etoposide is shown to cause inhibition of a specific p34cdc2 kinase activation pathway, that of tyrosine dephosphorylation. Exposure of asynchronously dividing cells to etoposide caused a simultaneous rapid decline of both mitotic index and p34cdc2 kinase activity, suggesting that the kinase was not activated and that the arrest point was in late G2 phase. Using synchronized cells, p34cdc2 kinase exhibited maximal activity at the G2/M transition. Activation of the kinase and the onset of mitosis were accompanied by increased electrophoretic mobility and tyrosine dephosphorylation of the p34cdc2 protein. A 1-h exposure to etoposide during early G2 phase inhibited p34cdc2 kinase activation, its shift in electrophoretic mobility, and its tyrosine dephosphorylation, all of which correlated with a delay in mitotic progression. The interaction between the p34cdc2 and cyclin B proteins appeared unaffected under etoposide exposure conditions which resulted in greater than 70% inhibition of p34cdc2 kinase activity and almost complete cessation of transition into mitosis. These data suggest that mammalian cells express a DNA damage-responsive mechanism which controls mitotic progression at the level of p34cdc2 tyrosine dephosphorylation.     

The p53 nuclear localisation signal is structurally linked to a p34cdc2 kinase motif

We have identified a region of human p53 protein with striking homology to a sequence motif on Simian Virus 40 T antigen which includes the nuclear localisation signal. Mutation of basic amino acid residues in this region of p53 (residues 312 to 323; SSSPQPKKKP) compromises transport of p53 protein to the nucleus. The sequence functions efficiently as a nuclear localisation signal when fused to E. coli beta galactosidase. Serine 315 within this p53 structural motif is phosphorylated in vitro by the cell cycle kinase p34cdc2. Thus in both T antigen and p53, nuclear localisation signal and p34cdc2 kinase acceptor residue map to a contiguous region of primary amino acid sequence.     

CIS-diamminedichloroplatinum(II) inhibits p34cdc2 protein kinase in human lung-cancer cells

cis-Diamminedichloroplatinum(II) (CDDP) induced G₂-phase arrest in PC-9 human cancer cells. To elucidate how CDDP acts on cell-cycle regulation, we analyzed the effect of CDDP on cell-cycle regulators such as p34^cdc2 protein kinase. p34^cdc2 protein kinase activity was maximum in G₂ phase and decreased after G₂/M transition in synchronized PC-9 human lung cancer cells. Evidence for a phosphorylated p34^cdc2 protein kinase complexed with cyclin B was obtained from cells in G₂ phase and the p34^cdc2 protein kinase appeared to be dephosphorylated at M phase. After exposure to CDDP in G, phase, PC-9 cells were arrested in G₂ phase. The activation of p34^cdc2 protein kinase was inhibited by CDDP. Cyclin A and wee-1 kinase were not affected by the exposure to CDDP. Cyclin B was degraded in M phase in PC-9 cells. Exposure to CDDP did not affect the degradation of cyclin B. Our data suggest that the effect of CDDP on cell-cycle phase might be regulated by the dephosphorylation of p34^cdc2 protein kinase. To determine whether the p34cdc2 protein kinase is a primary target for CDDP, we examined the direct effect of CDDP on tyrosine dephosphorylation of p34^cdc2 protein kinase in cellular extracts. Cell lysates from synchronized PC-9 in G₂ phase were immunoprecipitated with p 13-Sepharose beads. In vitro dephosphorylation of phosphotyrosine of p34^cdc2 protein kinase was observed after exposure to okadaic acid in a concentration-dependent manner. The dephosphorylation of p34^cdc2 protein kinase by okadaic acid was inhibited by CDDP. We hypothesize that inhibition of p34^cdc2 dephorphorylation by CDDP is important for its growth-inhibiting properties.     

Effect of melphalan and hyperthermia on p34cdc2 kinase activity in human melanoma cells.

We previously reported that combined treatment with melphalan and mild hyperthermia (1 h at 42 degrees C) caused a synergistic cytotoxic effect in JR8 melanoma cells, paralleled by a stabilisation of a melphalan-induced G2-phase cell block. In this study, we investigated the effect of melphalan and hyperthermia on proteins that regulate G2-M transition. Neither hyperthermia nor melphalan at a concentration of 2.5 micrograms ml-1, which had no antiproliferative effect at 37 degrees C, interfered with cyclin B1 expression or p34cdc2 kinase activity. At a concentration of 8.5 micrograms ml-1, which reduced cell growth by 50% at 37 degrees C, melphalan inhibited p34cdc2 kinase activity as a consequence of an increased tyrosine phosphorylation of the protein. A similar inhibitory effect on p34cdc2 kinase was obtained when the lowest melphalan concentration (2.5 micrograms ml-1) was used under hyperthermic conditions. Our results indicate that thermal enhancement of melphalan cytotoxicity could be mediated at least in part by an inhibition of p34cdc2 kinase activity, which prevents cell progression into mitosis.     

Expression patterns of polo-like kinase 1 in human gastric cancer

Polo-like kinase 1 (PLK1) is centrally involved in the regulation of mitosis in normal and malignant cells. It is known that inhibition of PLK1 expression in vitro and in vivo leads to mitotic arrest, induction of apoptosis and suppression of tumor growth. In the present study, expression of PLK1 was investigated in paraffin tissue of 135 cases of gastric adenocarcinoma and in 46 corresponding lymph node metastases by immunohistochemistry. Expression data were correlated with clinicopathological parameters and patient survival. Seventy-three (54.1%) of 135 carcinomas showed an overexpression of PLK1 compared to normal gastric mucosa. Overexpression of PLK1 correlated positively with tumor stage, nodal status and diffuse growth pattern. PLK1 expression in the primary tumor did not differ from PLK1 expression in the corresponding lymph node metastases. PLK1 expression was a significant prognostic factor in univariate but not in multivariate survival analysis. As a conclusion, upregulated PLK1 expression in gastric cancer correlates with a malignant tumor phenotype and has impact on patient prognosis. These data underscore the importance of PLK1 in gastric carcinogenesis and present a translational link for functional data into potential clinical use by defining PLK1 as an attractive protein for novel targeted chemotherapeutic approaches in gastric cancer.     

Possible role for p34cdc2 kinase in etoposide-induced cell death of Chinese hamster ovary cells

In an effort to shed light upon the processes of antitumor drug-induced cell death, we have carried out a systemic study of the effects of the anti-topoisomerase II agent, etoposide, on Chinese hamster ovary cells. Treatment of Chinese hamster ovary cells for 1 h with a 2-log cell-killing concentration of etoposide induces a high incidence of DNA single-strand breaks which are rapidly repaired upon drug removal. p34cdc2 kinase activity is inhibited within 1 h of addition of etoposide. Following removal of drug, cells accumulate transiently in G2. Upon recovery of p34cdc2 kinase activity (between 12 and 24 h posttreatment), approximately 50% of cells progress through mitosis which results in micronucleation. Examination of mitotic figures at various posttreatment incubation times indicates that micronucleation of daughter cells could be attributed to abnormal segregation of chromosomes during mitosis. Unexpectedly, p34cdc2 kinase activity remains elevated relative to untreated controls until 36 h post-etoposide treatment, a point where no further cell division takes place. This activity decreases by 48 h posttreatment, concomitant with a decrease in cell viability as estimated by the ability to exclude trypan blue. These results indicate that etoposide may induce cytotoxicity via gross chromosomal fragmentation, and that p34cdc2 kinase may be involved in this process.     

Expression of polo-like kinase in ovarian cancer is associated with histological grade and clinical stage

Polo-like kinase (PLK), a cell cycle-regulated, cyclin-independent serine/threonine protein kinase, has been shown in recent reports to play a critical role during tumorigenesis. To investigate whether PLK plays a general role as a tumor marker of ovarian cancers, we examined the expression of PLK protein in ovarian cancers, and analyzed the relationship between PLK protein expression and histological grade. Immunohistochemically, the majority of PLK was found in the cytoplasm (around the nucleus), and a portion was found in the nucleus of ovarian cancer glands and also in the fluid secreted from these glands. PLK was expressed at the basement membrane of cancer glands and partly expressed in the head portion of papillary cancer tissues. A significant correlation was found between percentages of PLK-positive cells and histological grade of ovarian cancer (P<0.001). However, the expression of proliferating cell nuclear antigen, Ki-67, and cyclin B1 was independent of PLK expression. Taken together, these findings suggest that PLK expression may reflect the degree of malignancy rather than the degree of proliferation in ovarian cancer. Thus, in addition to being of diagnostic value, PLK activity in ovarian tumors may be modulated by chemotherapeutic agents or gene therapy to therapeutic effect.