子宫颈癌组织p16基因突变及其蛋白表达研究

目的研究子宫颈癌患者p16蛋白表达和p16基因缺失突变及点突变情况.方法利用免疫组织化学方法(SP法)、聚合酶链反应(PCR)和聚合酶链反应-单链构象多态性(PCR-SSCP)分析技术,分别检测正常子宫颈组织30例、子宫颈癌前病变组织10例及原发性子宫颈癌组织28例,观察其p16蛋白表达和p16基因缺失突变及点突变状况.结果 1)在原发性子宫颈癌组织中为67.85%(19/28),明显低于正常子宫颈组织和子宫颈癌前病变组织(P<0.05);2)28例原发性子宫颈癌组织中有11例发生p16基因缺失突变,2例发生p16基因点突变,突变率为46.42%,正常子宫颈组织和子宫颈癌前病变组织未发现p16基因缺失突变和点突变.结论 1)p16蛋白缺乏与子宫颈细胞增殖失控及分化不良紧密相关.2)原发性子宫颈癌存在p16基因点突变,以低分化癌多见,但不是较频繁的事件;原发性子宫颈癌存在p16基因缺失突变,以低分化癌多见,是较频繁的事件.3)未发现p16蛋白表达与p16基因突变有相关性.     

人原发性肝癌中p16,p15基因CpG岛甲基化研究

目的　检测人原发性肝癌中 p16和 p15基因 5’启动子区CpG岛的异常甲基化 ,并分析其与人原发性肝癌发生发展的关系 ,探索其在临床早期基因诊断和治疗中的意义 .方法　用敏感的甲基化特异性PCR检测 2 0例人原发性肝癌患者癌组织、癌旁组织和远癌正常组织中p16 ,p15基因5’CpG岛的甲基化状况 ,统计分析这两个基因 5’CpG岛甲基化与肝癌病理特征的相关性 .结果　2 0例原发性肝癌肝癌组织中 p16和 p15基因 5’CpG岛分别有 6 5 %(13/2 0 )和 5 0 %(10 /2 0 )异常甲基化 ;癌旁组织中 p16和 p15基因 5’CpG岛分别有 6 0 %(12例 )和 4 0 %(8例 )异常甲基化 ;远癌正常组织中p16和 p15基因 5’CpG岛分别有 35 %(7例 )和 2 5 %(5例 )异常甲基化 .p16 ,p15基因 5’CpG岛甲基化在癌组织和癌组织旁、癌组织和远癌组织中均有相关性 .两个基因 5’CpG岛异常甲基化与临床病理特征无显著相关性 .结论　p16和 p15基因 5’CpG岛异常甲基化在人原发性肝癌中频率很高 ,可能在肝癌发生发展中扮演了重要角色 ;而...     

原发性子宫内膜癌与p16基因突变及蛋白表达关系的研究

目的研究p16蛋白表达与原发性子宫内膜癌发生发展的关系和p16基因缺失突变及点突变在原发性子宫内膜癌发生发展中的地位.方法利用免疫组织化学方法、聚合酶链反应和聚合酶链反应-单链构象多态性分析技术,分别检测正常子宫内膜组织、子宫内膜癌前病变组织及原发性子宫内膜癌组织,观察p16蛋白和p16基因缺失突变及点突变.结果1)p16蛋白阳性表达率在正常子宫内膜组织和子宫内膜癌前病变组织中表达率分别为92.78%和90.00%,两者相比无差异性;在原发性子宫内膜癌组织中为66.67%,明显低于正常子宫组织及癌前病变组织;2)在42例原发性性子宫内膜癌组织中有14例发生p16基因缺失突变,4例发生了p16基因点突变,突变率为分别为33.33%和9.6%,正常子宫颈组织和子宫内膜癌前病变组织未发现p16基因缺失突变和点突变.结论1)在原发性子宫内膜癌发生发展过程中,p16蛋白的表达在高分化癌明显低于低分化癌,表明p16蛋白缺乏与子宫颈细胞增殖失控及分化不良紧密相关.2)原发性子宫内膜癌存在p16基因点突变,以低分化癌多见,但不是较频繁的事件;原发性子宫内膜癌存在p16基因缺失突变,以低分化癌多见,是较频繁的事件.3)p16蛋白表达与p16基因突变的相关性未被发现.     

毛冠鹿p16INK4基因第二外显子序列分析

采用PCR扩增技术首次克隆毛冠鹿p16INK4基因第二外显子,DNA杂交和序列分析发现，在307个碱基的第二外显子中仅有5个碱基的差异，同源性达98.4%.p16INK4基因的第二外显子是高度保守的区域，在其功能中起重要作用.     

p16和HPV基因分型对宫颈上皮内瘤变的诊断价值研究

采用基因芯片技术及免疫组化法,对62例CIN组织(30例CINⅠ、17例CINⅡ、15例CINⅢ)进行HPV基因分型及p16基因表达检测.提示p16基因和HPV基因在宫颈CIN组织中的阳性表达率与对照组相比均有显著差异(P<0.01);p16在正常宫颈中无表达,而随着宫颈病变的进展,p16的表达率显著升高(P<0.01),且与HPV有相关性.表明p16在一定程度上可反映HPV的感染程度,可作为宫颈病变及宫颈癌筛查敏感的客观性指标;HPV联合p16基因检测能显著提高宫颈病变的准确性.     

人p16~(INK4) cDNA探针在非小细胞肺癌研究中的应用

制备总RNA ,RT PCR克隆p16 INK4 cDNA ,测序验证 ,制备探针 .进行PCR产物Southern杂交检测非小细胞肺癌组织标本中p16 INK4 基因第二外显子阴性杂交率为 12 .9% (4 / 31) .原位杂交显示p16 INK4 基因转录阴性率为2 2 .6 % (7/ 31) .结果说明克隆的p16 INK4 cDNA是正确的 ,可用于临床基因诊断 ,p16 INK4 基因变异及表达在非小细胞肺癌的发生、发展中起作用     

甲状腺癌组织端粒酶激活与p16基因失活的关系

目的探讨甲状腺癌细胞增殖、分化与端粒酶激活及抑癌基因p16失活（缺失突变）之间可能存在的关系。方法应用TRAP、多重PCR、免疫组化法检测42例甲状腺癌与16例癌旁组织端粒酶活性、P16基因外显子2缺失、P16蛋白表达。结果甲状腺癌组端粒酶活性90．48％,高于癌旁组织（P〈0．01）;甲状腺癌p16基因外显子2纯合缺失率28．57％,相应癌旁组未检出（P〈0．01）;甲状腺癌P16蛋白表达缺失率40．48％,高于癌旁组（P〈0．05）;甲状腺癌P16蛋白表达缺失率高于p16基因外显子2缺失率。结论端粒酶激活与p16基因失活以及P16蛋白表达下调可能是甲状腺癌变过程中的重要分子事件,甲状腺癌中p16基因失活可能是端粒酶激活的一种途径。     

视黄酸及干扰素对胃癌细胞系MKN45中p16,p21,c-myc基因表达的影响

目的探讨全反式视黄酸及干扰素两种因子对胃癌MKN45细胞的影响.方法将视黄酸及干扰素同时加入胃癌细胞系MKN45中进行细胞培养,用MTT法测定细胞的生长状况,并通过Northern blot和免疫组化测定p16,p21及c-myc的表达情况.结果干扰素(IFN)协同全反式视黄酸(ATRA)可有效地抑制MKN45细胞生长,癌细胞经联合用药诱导后p16和p21基因的表达水平提高,c-myc基因表达水平下降.视黄酸受体RARα基因在MKN45细胞中呈低水平表达,经ATRA和IFN诱导后表达水平提高.结论 ATRA联合IFN诱导可调节p16和p21基因的表达水平,抑制胃癌MKN45细胞生长,这可能与细胞中RARα基因高水平表达有一定关系.     

血浆p16基因甲基化在原发性肝细胞癌诊断中的作用

用甲基化特异性-多聚酶链反应（MSP）方法, 检测原发性肝细胞癌（HCC）、 肝硬 化、 慢性肝炎病人及健 康人各30例的血浆DNA甲基化的p16基因. 结果显示, HCC病人血浆p16 基因甲基化率为67%, 慢性肝炎、 肝硬化及健康者未发生甲基化.     

子宫颈癌抑癌基因P16第一外显子CpG岛异常甲基化

利用限制性核酸内切酶-PCR方法分析33例肿瘤组织和15例正常组织抑癌基因p16第一外显子SacⅡ和SmaⅠ酶切位点甲基化,应用SPSS软件进行统计分析。结果显示,18例子宫颈癌在抑癌基因p16第一外显子SacⅡ位点甲基化,8例子宫颈癌在SmaⅠ位点甲基化。正常组织仅有两例在抑癌基因p16第一外显子SacⅡ位点甲基化,正常组织在SmaⅠ位点没有甲基化。另外,抑癌基因p16第一外显子SacⅡ和SmaⅠ酶切位点甲基化易发生在肿瘤的早期。抑癌基因p16第一外显子SacⅡ和SmaⅠ酶切位点甲基化与子宫颈癌相关。     

抑癌基因p27在肿瘤细胞MCF7中的表达

抑癌基因p27是一个细胞周期依赖性激酶抑制子CKI(CDK inhibitor),对细胞周期起着负调控的作用,将p27基因克隆到表达载体pcDNA,转染到肿瘤细胞MCF7中,筛选到稳定表达株．p27基因的过量表达确实对肿瘤细胞的生长产生了抑制作用,并且引发了部分肿瘤细胞的凋亡．     

Triggering of cyclin degradation in interphase extracts of amphibian eggs by cdc2 kinase

The cell cycles of early Xenopus embryos consist of a rapid succession of alternating S and M phases. These cycles are controlled by the activity of a protein kinase complex (cdc2 kinase) which contains two subunits. One subunit is encoded by the frog homologue of the fission yeast cdc2+ gene, p34cdc2 and the other is a cyclin. The concentration of cyclins follows a sawtooth oscillation because they accumulate in interphase and are destroyed abruptly during mitosis. The association of cyclin and p34cdc2 is not sufficient for activation of cdc2 kinase, however; dephosphorylation of key tyrosine and threonine residues of p34cdc2 is necessary to turn on its kinase activity. The activity of cdc2 kinase is thus regulated by a combination of translational and post-translational mechanisms. The loss of cdc2 kinase activity at the end of mitosis depends on the destruction of the cyclin subunits. It has been suggested that this destruction is induced by cdc2 kinase itself, thereby providing a negative feedback loop to terminate mitosis. Here we report direct experimental evidence for this idea by showing that cyclin proteolysis can be triggered by adding cdc2 kinase to a cell-free extract of interphase Xenopus eggs.     

Dephosphorylation and activation of a p34cdc2/cyclin B complex in vitro by human CDC25 protein.

Oocytes arrested in the G2 phase of the cell cycle contain a p34cdc2/cyclin B complex which is kept in an inactive form by phosphorylation of its p34cdc2 subunit on tyrosine, threonine and perhaps serine residues. The phosphatase(s) involved in p34cdc2 dephosphorylation is unknown, but the product of the fission yeast cdc25+ gene, and its homologues in budding yeast and Drosophila are probably positive regulators of the transition from G2 to M phase. We have purified the inactive p34cdc2/cyclin B complex from G2-arrested starfish oocytes. Addition of the purified bacterially expressed product of the human homologue of the fission yeast cdc25+ gene (p54CDC25H) triggers p34cdc2 dephosphorylation and activates H1 histone kinase activity in this preparation. We propose that the cdc25+ gene product directly activates the p34cdc2-cyclin B complex.     

Distinct nuclear and spindle pole body population of cyclin-cdc2 in fission yeast.

Cyclins, as subunits of the protein kinase encoded by the cdc2 gene are major controlling elements of the eukaryotic cell cycle. The fission yeast Schizosaccharomyces pombe has a B-type cyclin, which is a nuclear protein encoded by the cdc13 gene. Here we demonstrate the presence of two spatially distinct cdc13 cyclin populations in the nucleus of S. pombe, one of which is associated with the mitotic spindle poles. Both populations colocalize with the product of the cdc2 gene (p34cdc2). Treatment of cells with the antimicrotubule drug thiabendazole prevents cyclin degradation and blocks the tyrosine dephosphorylation and activation of cdc2. These results suggest a key regulatory role of the cdc2-cyclin complex in the initiation of mitotic spindle formation and also that mitotic microtubule function is required for cdc2 activation.     

Loss of p16Ink4a with retention of p19Arf predisposes mice to tumorigenesis.

The cyclin-dependent kinase inhibitor p16INK4a can induce senescence of human cells, and its loss by deletion, mutation or epigenetic silencing is among the most frequently observed molecular lesions in human cancer. Overlapping reading frames in the INK4A/ARF gene encode p16INK4a and a distinct tumour-suppressor protein, p19ARF (ref. 3). Here we describe the generation and characterization of a p16Ink4a-specific knockout mouse that retains normal p19Arf function. Mice lacking p16Ink4a were born with the expected mendelian distribution and exhibited normal development except for thymic hyperplasia. T cells deficient in p16Ink4a exhibited enhanced mitogenic responsiveness, consistent with the established role of p16Ink4a in constraining cellular proliferation. In contrast to mouse embryo fibroblasts (MEFs) deficient in p19Arf (ref. 4), p16Ink4a-null MEFs possessed normal growth characteristics and remained susceptible to Ras-induced senescence. Compared with wild-type MEFs, p16Ink4a-null MEFs exhibited an increased rate of immortalization, although this rate was less than that observed previously for cells null for Ink4a/Arf, p19Arf or p53 (refs 4, 5). Furthermore, p16Ink4a deficiency was associated with an increased incidence of spontaneous and carcinogen-induced cancers. These data establish that p16Ink4a, along with p19Arf, functions as a tumour suppressor in mice.     

CDK16在食管鳞癌中的表达及其对肿瘤发生发展的影响

目的研究发现,细胞周期素依赖性激酶(cyclin dependent kinases,CDKs)家族成员与食管鳞癌的发病密切相关,但细胞周期素依赖性激酶16(CDK16)对食管鳞癌发病的影响尚不清楚.本研究旨在探讨CDK16在人食管鳞癌组织中的表达及生物学意义.方法应用组织芯片技术结合免疫组织化学技术检测45例食管鳞癌组织、45例癌旁组织中CDK16蛋白的表达情况,并使用统计分析软件研究CDK16蛋白的表达与食管鳞癌临床病理特征之间的关系.结果 CDK16在食管鳞癌组织中呈阳性表达,且表达强度与肿瘤分化程度呈负相关.另外,CDK16在食管鳞癌细胞中的表达位置与肿瘤的分化程度紧密相关.CDK16的表达与食管鳞癌的分化程度、淋巴结转移及TNM临床分期均具有显著的相关性(P<0.05),而与患者的年龄、性别以及肿瘤的部位、最大径、病理形态没有显著的相关性(P>0.05).结论 CDK16在食管鳞癌中的高表达与食管鳞癌的发生发展及转移密切相关.检测CDK16的表达有助于食管鳞癌的临床诊断和预后评估.     

Phosphorylation of Erp1 by p90rsk is required for cytostatic factor arrest in Xenopus laevis eggs

Until fertilization, the meiotic cell cycle of vertebrate eggs is arrested at metaphase of meiosis II by a cytoplasmic activity termed cytostatic factor (CSF), which causes inhibition of the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase that targets mitotic cyclins-regulatory proteins of meiosis and mitosis-for degradation. Recent studies indicate that Erp1/Emi2, an inhibitor protein for the APC/C, has an essential role in establishing and maintaining CSF arrest, but its relationship to Mos, a mitogen-activated protein kinase (MAPK) kinase kinase that also has an essential role in establishing CSF arrest through activation of p90 ribosomal S6 kinase (p90rsk), is unclear. Here we report that in Xenopus eggs Erp1 is a substrate of p90rsk, and that Mos-dependent phosphorylation of Erp1 by p90rsk at Thr 336, Ser 342 and Ser 344 is crucial for both stabilizing Erp1 and establishing CSF arrest in meiosis II oocytes. Semi-quantitative analysis with CSF-arrested egg extracts reveals that the Mos-dependent phosphorylation of Erp1 enhances, but does not generate, the activity of Erp1 that maintains metaphase arrest. Our results also suggest that Erp1 inhibits cyclin B degradation by binding the APC/C at its carboxy-terminal destruction box, and this binding is also enhanced by the Mos-dependent phosphorylation. Thus, Mos and Erp1 collaboratively establish and maintain metaphase II arrest in Xenopus eggs. The link between Mos and Erp1 provides a molecular explanation for the integral mechanism of CSF arrest in unfertilized vertebrate eggs.     

Chk1 prevents abnormal mitosis of S-phase HeLa cells containing DNA damage

To explore effects of DNA damage on cell-cycle progression in p53-deficient tumor cells, synchronized HeLa cells at G1, S and G2/M phases were treated with methyl methanesulfnate （MMS）. The results showed that the MMS treatment resulted in the cell-cycle arrest or delay in all 3 phases, while the S-phase cells were the most sensitive to MMS. Further studies demonstrated that ATM-Chk2 and p38 MAPK signaling pathways were activated in all 3 phases when the cells were treated with MMS; whereas Chk1 was activated only in S phase under the drug treatment, indicating that Chk1 specifically participated in S-phase checkpoints. To analyze the role of Chk1 in S-phase checkpoints, we administered a specific Chk1 inhibitor, UCN-01, to the S-phase cells. The results showed that the S-phase cells treated with MMS＋UCN-01 could enter aberrant mitosis without finishing DNA replication, indicating that Chk1 mainly functions in the DNA damage checkpoint rather than in the replication checkpoint. In addition, MMS treatment alone inhibited the accumulation of cyclin B1, a key component of M-phase CDK-cyclin complex, in the S-phase cells, whereas the inhibition of Chk1 activation resulted in the accumulation of cyclin B1 in the MMS-treated S-phase cells. This observation further supports the view that DNA-damaged S-phase cells enter abnormal mitosis when Chk1 activation is inhibited. Our results demonstrate that Chk1 is a specific kinase that plays an important role in the MMS-induced S-phase DNA damage checkpoint. As p53 is not involved in this process, Chk1 may be a potential target for p53-deficient tumor therapy.     

毛冠鹿p16^INK4基因第二外显子序列分析

采用PCR扩增技术首次克隆毛冠鹿p16^INK4基因第二外显子，DNA杂交和序列分析发现，在307个碱基的第二外显子中仅有5个碱基的差异，同源性达98．4％，p16^INK4基因的第二外显子是高度保守的区域，在其功能中起重要作用。