p16基因甲基化与表达在子宫内膜癌中的意义

肿瘤抑制基因p16定位于9号染色体短臂2区1带,编码细胞周期调节蛋白p16,p16基因失活将导致细胞增殖失控。研究证实肿瘤抑制基因启动子区域5CpG岛甲基化是导致转录水平上基因失活的重要机制。为了研究p16基因甲基化状态及其表达异常与子宫内膜癌发生的关系,采用甲基化特异性PCR(MSP)、免疫组化及PCR方法检测62例子宫内膜癌及相应癌旁组织、10例相应年龄正常子宫内膜中p16基因5′cpG岛甲基化状态、p16蛋白表达及p16基因外显子E,和E：表达缺失情况。结果表明癌旁及正常子宫内膜p16基因无甲基化,且无p16蛋白、外显子1和2的表达异常。62例子宫内膜癌中,15例甲基化,占24、2％;33例p16蛋白表达下降或无表达,占54．8％;p16基因外显子1缺失率16．1％(10／62),外显子2缺失率为30．6％(19／62),两者均缺失9．68％(6／62),至少其中1种缺失46、6％(29／62)。提示P16基因失活在子宫内膜癌中多见且与病理分级、临床分期密切相关。D16基因甲基化在子宫内膜癌的发生中起着重要作用。MSP法测定基因甲基化状态准确且简便可行。     

p16基因甲基化状态与散发性大肠癌的相关性研究

为探讨p1 6基因甲基化状态与散发性大肠癌发生发展的关系 ,用甲基化特异性的聚合酶链反应 (methylati omspecificPCR ,MSP)结合测序检测散发性大肠癌及相应癌旁组织p1 6基因甲基化状态。研究发现p1 6基因在散发性大肠癌中甲基化率为 2 8 9% (1 3 4 5 ) ,有 8例癌及癌旁组织都发生了甲基化 ;有淋巴结及远处转移的甲基化率为5 0 % (8 1 6 ) ,高于无转移的甲基化率 2 0 8(5 2 4 ) (P <0 0 5 )。p1 6基因高甲基化是散发性大肠癌中常见的分子改变之一 ,大肠癌中p1 6基因高甲基化可能发生在癌变早期并与大肠癌的恶性进展有相关性     

宫颈癌p16基因甲基化及表达的研究

为了探讨p16基因甲基化及异常表达在宫颈癌中的意义,分别采用甲基化特异性PCR（MSP）方法检测不同病理类型和临床分期的60例宫颈癌组织中p16基因启动子区域5´CpG岛甲基化状态;采用PCR方法检测p16基因外显子1（E1)和外显子2(E2)纯合缺失情况;采用免疫组化的方法分析p16蛋白的表达缺失和减弱情况。结果显示正常对照组织及癌旁p16基因无甲基化,且无E1和E2缺失和p16蛋白表达异常。60例宫颈癌标本的甲基化率为21.67%（13/60）;p16 基因缺失率为15.00%（9/60）;p16蛋白表达下降或无表达为51.67%（31/60）。可见p16基因蛋白的阳性表达率随着临床分期升高呈明显下降趋势。结果提示p16基因失活在宫颈癌中多见且与病理分级密切相关。p16 基因甲基化在宫颈癌发生中起着一定作用。Abstract： To detect hypermethylation and aberrant expression of the p16 gene in cervical carcinoma (CC), methylation-specific PCR (MSP) was used to determine the methylation status of 5´CpG islands of the p16 gene, loss or decrease of p16 expression was analyzed by immunohistochemistry (IHC), and homozygous deletion of exon 1 (E1) and/or exon 2 (E2) was determined by PCR. in 60 cases of CC at different pathological grades and clinical stages. The results showed absence of methylation and presence of normal expression of the p16 gene in the control and adjacent tissues of CC. Hypermethylation, loss or decrease of expression and deletion of the p16 gene were detected in 21.67%(13/60), 51.67%(31/60) and 15.00%(9/60) of the tumor tissues, respectively. The rate of p16 expression markedly reduced with the increase of clinical stages. Our data suggested that inactivation of the p16 gene was a frequent event and positively correlated with pathological grades in CC, and that methylation of the p16 gene was an important event in carcinogenesis of CC.     

DACT2基因启动子甲基化与宫颈癌细胞化疗敏感性的相关性研究

摘要 目的：探讨与研究DACT2基因启动子甲基化与宫颈癌细胞化疗敏感性的相关性。方法：人宫颈癌顺铂耐药细胞系SIHA/DDP根据实验目的分为三组-对照组、DACT 1组与DACT 2组,组分别加入含0.0 μmol/L、1.0 μmol/L、10.0 μmol/L DACT2基因启动子甲基化抑制剂-5-aza-dC进行治疗,采用MTT法检测细胞增殖指数,流失细胞法检测细胞凋亡指数,PCR法检测甲基化水平,流式细胞仪检测胞周期,Western Blot检测Wnt蛋白与TGF-β1蛋白表达情况。结果：治疗后24 h、36 h的DACT 1组与DACT 2组DACT2基因启动子甲基化相对水平低于对照组(P<0.05),DACT 2组低于DACT 1组(P<0.05)。治疗后24 h、36 h的DACT 1组与DACT 2组细胞增殖指数低于对照组(P<0.05),细胞凋亡指数高于对照组(P<0.05),DACT 2组与DACT 1组对比差异都有统计学意义(P<0.05)。治疗后24 h、36 h的DACT 1组与DACT 2组G2/M期细胞比例高于对照组(P<0.05),G0/G1期细胞比例低于对照组(P<0.05),DACT 1组与DACT 2组对比差异有统计学意义(P<0.05)。治疗后24 h、36 h的DACT 1组与DACT 2组的Wnt蛋白与TGF-β1蛋白相对表达水平低于对照组(P<0.05),DACT 2组低于DACT 1组(P<0.05)。结论：抑制DACT2基因启动子甲基化能抑制宫颈癌细胞的Wnt/TGF-β1信号通路的激活,能调节宫颈癌细胞周期平衡,能抑制顺铂耐药性宫颈癌细胞增殖,促进细胞凋亡,并增强化疗敏感性,且在本研究设置范围内,作用剂量越高,效果越显著。     

反义p73基因诱导人肝癌细胞HepG2的凋亡

目的：构建表达重组反义p73基因的重组逆转录病毒,观察其对人肝癌细胞HepG2的凋亡诱导活性,并进一步探讨其作用机制。方法：克隆p73基因的反义片段,重组法构成逆转录病毒载体pBabe-p73（pBP73）,以脂质体Lipofectamine2000将其转染293A细胞进行病毒包装;将逆转录病毒感染人肝癌细胞HepG2,用MTT法检测细胞生长抑制情况,Western blotting检测p73的表达;再分别用琼脂糖凝胶电泳和流式细胞仪检测肿瘤细胞的凋亡;最后检测p53,caspase-3和bcl-2蛋白的表达变化。结果  重组质粒pBP73经鉴定连接正确,其转染293A细胞后上清液中可得到病毒,滴度达5×107pfu;MTT检测见pBP73病毒组48和72h细胞抑制率高于对照组（45.1% vs. 5.3%,69.5% vs.17.3%,均p<0.05）。琼脂糖凝胶电泳出现典型梯形条带;流式细胞仪检测出现凋亡峰,于转染48h后达最高峰,其凋亡百分率高达20.47%;p73蛋白高表达组p53和caspase-3蛋白的表达亦有显著升高（p<0.05）,但bcl-2蛋白未见表达差异。结论：成功构建了p73逆转录病毒,反义p73基因在体外能够有效地诱导人肝癌细胞HepG2的凋亡,其可能机制是通过激活caspase-3而发生作用。     

痰液脱落细胞中p16 基因和RASSF1A 基因甲基化与周边型非小细胞 肺癌关系的研究

目的:探讨p16基因和RASSF1A基因甲基化与肺癌发生发展的关系和应用于诊断的意义。方法:采用甲基化特异性PCR(Methylation Specific PCR,MSP)检测120例周边型非小细胞肺癌患者癌组织、痰液脱落细胞和120例非肺癌人群的痰液脱落细胞中p16基因和RASSF1A基因甲基化,分析它们与临床特征的关系以及非肺癌人群与肿瘤患者之间的差异。结果:(1)120例周边型非小细胞肺癌组织中,p16基因甲基化率46.7%(56例),RASSF1A基因甲基化率53.3%(64例)。P16和RASSF1A基因甲基化与吸烟程度、肿瘤大小和临床分期正相关(P<0.05)。(2)肺癌痰液脱落细胞中有28例p16基因出现甲基化(23.3%),20例RASSF1A基因出现甲基化(16.7%),其中32例至少存在一个基因的甲基化(26.7%);66例重度吸烟者中只有4例痰液脱落细胞出现p16基因甲基化(6%),4例出现RASSF1A基因甲基化(6%);54例非重度吸烟正常人中仅有2例出现p16基因甲基化(3.7%),RASSF1A基因无甲基化。(3)液基痰细胞病理学检查与痰脱落细胞p16和RASSF1a基因甲基化检测结合起来可有效提高诊断的灵敏度(P<0.05)。结论:烟草可能具有潜在的诱导抑癌基因p16和RASSF1A发生甲基化的作用;p16和RASSF1A基因甲基化可能参与肺癌的生长过程。痰脱落细胞p16和RASSF1a基因甲基化检测结合液基痰细胞病理学诊断,可提高非小细胞肺癌诊断的灵敏度。     

细胞凋亡过程中bcl-2基因的甲基化

为探讨凋亡过程中,ｂｃｌ－２基因下调与该基因甲基化状态的关系,用５－氟尿嘧啶（５－Ｆｕ）诱导小鼠成纤维细胞ＮＣ３Ｈ１０,ＴＣ３Ｈ１０及人乳腺癌细胞ＭＣＦ－７的凋亡,分别检测了这三种细胞凋亡过程中ｂｃｌ－２的表达变化,与其调控区及编码区的甲基化状况．我们曾观察到５－Ｆｕ作用２４～４８ｈ出现细胞存活率下降,ＤＮＡ梯状断裂及细胞周期凋亡峰显现等典型凋亡现象．Ｎｏｒｔｈｅｒｎ杂交显示,在５－Ｆｕ作用１２ｈ时ｂｃｌ－２ｍＲＮＡ水平已明显降低．由此,我们用小鼠ｂｃｌ－２（ｍｂｃｌ－２）及人ｂｃｌ－２（ｈｂｃｌ－２）基因调控区ＰＣＲ扩增片段及ｂｃｌ－２编码区（ｃＤＮＡ）片段作为探针,与５－Ｆｕ作用１２ｈ的细胞ＤＮＡ的ＭｓｐⅠ／ＨｐａⅡ酶切产物进行Ｓｏｕｔｈｅｒｎ杂交,以未作用的细胞ＤＮＡ同样酶切杂交为对照．通过杂交带谱的变化,分析ｂｃｌ－２基因的甲基化状况．结果显示：ｍｂｃｌ－２及ｈｂｃｌ－２在５－Ｆｕ作用１２ｈ后调控区甲基化水平增高,但其编码区甲基化状态皆未出现可检出的变化．上述结果提示：ｂｃｌ－２基因调控区甲基化水平升高可能与该基因下调有关     

低剂量顺铂通过p38MAPK介导的DNMT1下调降低p21与p16启动子甲基化上调p21与p16表达

低剂量顺铂可通过诱导p21与p16表达而诱导肿瘤细胞早衰,但其机制不明。本研究探讨了低剂量顺铂诱导的HeLa细胞衰老过程中p21与p16的上调机制。低剂量顺铂（4 μmol/L）处理HeLa细胞后,DNA甲基转移酶DNMT1蛋白水平降低;p21与p16启动子甲基化水平降低,二者mRNA及蛋白质水平升高;顺铂对DNMT1蛋白水平的降低作用与其激活p38MAPK有关,用SB203580抑制p38MAPK可部分逆转顺铂对DNMT1蛋白水平以及p21与p16启动子甲基化的降低作用,从而部分逆转顺铂对p21与p16表达的诱导;抑制p38MAPK 也可部分逆转低剂量顺铂诱导的HeLa细胞早衰。上述结果表明,低剂量顺铂可通过p38MAPK信号通路下调p21与p16启动子甲基化水平,进而上调二者的表达。这些结果为解析低剂量顺铂诱导肿瘤细胞早衰的信号转导机制提供了实验依据。     

微流控芯片检测肺癌患者血浆中p16基因异常甲基化在临床应用的评价

肺癌是常见的恶性肿瘤之一,其死亡率和发病率在世界范围的肿瘤性疾病中均居高不下.p16基因启动子区异常甲基化被认为是肺癌发生中的一起早期事件.为了提高检测异常甲基化方法的灵敏度及特异性,利用微流控芯片检测p16基因的异常甲基化,通过对肺癌患者血浆标本的检测,使病人血浆中的p16基因甲基化的异常改变可能成为辅助肺癌早期诊断和高危人群筛选的分子标记物,以期建立一种崭新而可靠的早期肺癌临床诊断方法.     

脑胶质瘤组织中p16基因启动子区CpG岛甲基化检测及其临床意义研究

目的：研究脑胶质瘤中p16基因启动子区甲基化情况及其临床意义。方法：用甲基化特异性PCR技术检测42例脑胶质瘤组织和癌旁正常脑组织中p16基因启动子甲基化,并分析该基因启动子甲基化与临床病理特征之间的关系。结果：脑胶质瘤组织中p16基因异常甲基化率（38.27%）显著高于癌旁正常脑组织中p16基因的异常甲基化率（8.8%,P=0.000）。发生甲基化的肿瘤组织或者正常脑组织中p16基因mRNA和蛋白表达显著降低。此外,p16基因异常甲基化和肿瘤病理分级有相关性（P=0.007）,而与患者性别、年龄及肿瘤类型等临床特征无关（P=0.669,0.869和0.944）。结论：p16基因启动子区CpG岛高甲基化与p16表达下调相关,推测p16启动子区CpG岛高甲基化是导致p16基因在脑胶质瘤中表达下调的重要因素,有望成为脑胶质瘤早期辅助诊断的分子标志物之一。     

The RASSF6 Tumor Suppressor Protein Regulates Apoptosis and the Cell Cycle via MDM2 Protein and p53 Protein

Ras association domain family (RASSF) 6 is a member of the C-terminal RASSF proteins such as RASSF1A and RASSF3. RASSF6 is involved in apoptosis in various cells under miscellaneous conditions, but it remains to be clarified how RASSF6 exerts tumor-suppressive roles. We reported previously that RASSF3 facilitates the degradation of MDM2, a major E3 ligase of p53, and stabilizes p53 to function as a tumor suppressor. In this study, we demonstrate that RASSF6 overexpression induces G₁/S arrest in p53-positive cells. Its depletion prevents UV- and VP-16-induced apoptosis and G₁/S arrest in HCT116 and U2OS cells. RASSF6-induced apoptosis partially depends on p53. RASSF6 binds MDM2 and facilitates its ubiquitination. RASSF6 depletion blocks the increase of p53 in response to UV exposure and up-regulation of p53 target genes. RASSF6 depletion delays DNA repair in UV- and VP-16-treated cells and increases polyploid cells after VP-16 treatment. These findings indicate that RASSF6 stabilizes p53, regulates apoptosis and the cell cycle, and functions as a tumor suppressor. Together with the previous reports regarding RASSF1A and RASSF3, the stabilization of p53 may be the common function of the C-terminal RASSF proteins.     

Phenformin Induces Cell Cycle Change,Apoptosis, and Mesenchymal-Epithelial Transition and Regulates the AMPK/mTOR/p70s6k and MAPK/ERK Pathways in Breast Cancer Cells

Breast cancer remains a world-wide challenge, and additional anti-cancer therapies are still urgently needed. Emerging evidence has demonstrated the potent anti-tumor effect of biguanides, among which phenformin was reported to potentially be a more active anti-cancer agent than metformin. However, little attention has been given to the role of phenformin in breast cancer. In this study, we reveal the role of phenformin in cell death of the MCF7, ZR-75-1, MDA-MB-231 and SUM1315 breast cancer cell lines. The respective IC₅₀ values of phenformin in MCF7, ZR-75-1, MDA-MB-231 and SUM1315 cells were 1.184±0.045 mM, 0.665±0.007 mM, 2.347±0.010 mM and 1.885±0.015 mM (mean± standard error). Phenformin induced cell cycle change and apoptosis in breast cancer cells via the AMPK/mTOR/p70s6k and MAPK/ERK pathways. Interestingly, phenformin induced MET (mesenchymal-epithelial transition) and decreased the migration rate in breast cancer cell lines. Furthermore, our results suggest that phenformin inhibits breast cancer cell metastasis after intracardiac injection into nude mice. Taken together, our study further confirms the potential benefit of phenformin in breast cancer treatment and provides novel mechanistic insight into its anti-cancer activity in breast cancer.     

CHD1L Regulates Cell Cycle,Apoptosis, and Migration in Glioma

Chromodomain helicase/ATPase DNA binding protein 1-like (CHD1L) gene is a newly identified oncogene located at Chr1q21 and it is amplified in many solid tumors. In this study, we intended to investigate the clinical significance of CHD1L expression in human glioma and its biological function in glioma cells. Western blot and immunohistochemistry analysis showed that CHD1L was overexpressed in glioma tissues and glioma cell lines. In addition, the expression level of CHD1L was positively correlated with glioma pathological grade and Ki-67 expression. Kaplan–Meier curve indicated that high expression of CHD1L may result in poor prognosis of glioma patients. Accordingly, suppression of CHD1L in glioma cells was shown to induce cell cycle arrest and increase apoptosis. In addition, knockdown of CHD1L significantly accelerated migration and invasion ability of glioma cells. Together our findings suggest that CHD1L is involved in the progression of glioma and may be a novel target for further therapy.     

Nephronophthisis-Associated CEP164 Regulates Cell Cycle Progression,Apoptosis and Epithelial-to-Mesenchymal Transition

We recently reported that centrosomal protein 164 (CEP164) regulates both cilia and the DNA damage response in the autosomal recessive polycystic kidney disease nephronophthisis. Here we examine the functional role of CEP164 in nephronophthisis-related ciliopathies and concomitant fibrosis. Live cell imaging of RPE-FUCCI (fluorescent, ubiquitination-based cell cycle indicator) cells after siRNA knockdown of CEP164 revealed an overall quicker cell cycle than control cells, although early S-phase was significantly longer. Follow-up FACS experiments with renal IMCD3 cells confirm that Cep164 siRNA knockdown promotes cells to accumulate in S-phase. We demonstrate that this effect can be rescued by human wild-type CEP164, but not disease-associated mutants. siRNA of CEP164 revealed a proliferation defect over time, as measured by CyQuant assays. The discrepancy between accelerated cell cycle and inhibited overall proliferation could be explained by induction of apoptosis and epithelial-to-mesenchymal transition. Reduction of CEP164 levels induces apoptosis in immunofluorescence, FACS and RT-QPCR experiments. Furthermore, knockdown of Cep164 or overexpression of dominant negative mutant allele CEP164 Q525X induces epithelial-to-mesenchymal transition, and concomitant upregulation of genes associated with fibrosis. Zebrafish injected with cep164 morpholinos likewise manifest developmental abnormalities, impaired DNA damage signaling, apoptosis and a pro-fibrotic response in vivo. This study reveals a novel role for CEP164 in the pathogenesis of nephronophthisis, in which mutations cause ciliary defects coupled with DNA damage induced replicative stress, cell death, and epithelial-to-mesenchymal transition, and suggests that these events drive the characteristic fibrosis observed in nephronophthisis kidneys.     

HBV影响XRN2基因在HepG2-H7细胞中表达的机制研究

目的利用稳定表达HBV的HepG2-H7细胞,研究HBV对XRN2基因表达的调控,并对其作用机制进行初步探讨。方法用RT—PCR和Real-time PCR的方法检测HepG2细胞及稳定表达HBV的HepG2-H7细胞中XRN2在mRNA水平的表达差异。构建XRN2启动子的萤火虫荧光素酶报告质粒,分别转染HepG2细胞及HepG2-H7细胞,检测HBV对XRN2启动子的影响。将XRN2启动子质粒与HBV4种蛋白的真核表达质粒共转染HepG2细胞,寻找对启动子影响较大的HBV蛋白。结果RT—PCR和Real-time PCR的结果显示XRN2在HepG2-H7细胞中的表达较HepG2细胞有所下降。荧光素酶活性分析显示HBV能抑制XRN2启动子的活性,且HBx和HBp蛋白在这一过程中起主要作用。结论HBV蛋白可以通过抑制XRN2启动子活性调节其在HepG2-H7细胞中的表达。     

Phytometabolite Dehydroleucodine Induces Cell Cycle Arrest,Apoptosis, and DNA Damage in Human Astrocytoma Cells through p73/p53 Regulation

Accumulating evidence supports the idea that secondary metabolites obtained from medicinal plants (phytometabolites) may be important contributors in the development of new chemotherapeutic agents to reduce the occurrence or recurrence of cancer. Our study focused on Dehydroleucodine (DhL), a sesquiterpene found in the provinces of Loja and Zamora-Chinchipe. In this study, we showed that DhL displayed cytostatic and cytotoxic activities on the human cerebral astrocytoma D384 cell line. With lactone isolated from Gynoxys verrucosa Wedd, a medicinal plant from Ecuador, we found that DhL induced cell death in D384 cells by triggering cell cycle arrest and inducing apoptosis and DNA damage. We further found that the cell death resulted in the increased expression of CDKN1A and BAX proteins. A marked induction of the levels of total TP73 and phosphorylated TP53, TP73, and γ-H2AX proteins was observed in D384 cells exposed to DhL, but no increase in total TP53 levels was detected. Overall these studies demonstrated the marked effect of DhL on the diminished survival of human astrocytoma cells through the induced expression of TP73 and phosphorylation of TP73 and TP53, suggesting their key roles in the tumor cell response to DhL treatment.     

Gatifloxacin Induces S and G2-Phase Cell Cycle Arrest in Pancreatic Cancer Cells via p21/p27/p53

Pancreatic cancer, despite being the most dreadful among gastrointestinal cancers, is poorly diagnosed, and further, the situation has been aggravated owing to acquired drug resistance against the single known drug therapy. While previous studies have highlighted the growth inhibitory effects of older generation fluoroquinolones, the current study aims to evaluate the growth inhibitory effects of newer generation fluoroquinolone, Gatifloxacin, on pancreatic cancer cell lines MIA PaCa-2 and Panc-1 as well as to elucidate the underlying molecular mechanisms. Herein, we report that Gatifloxacin suppresses the proliferation of MIA PaCa-2 and Panc-1 cells by causing S and G₂-phase cell cycle arrest without induction of apoptosis. Blockade in S-phase of the cell cycle was associated with increased TGF-β1 expression and translocation of Smad3-4 complex to the nucleus with subsequent activation of p21 in MIA PaCa-2 cells, whereas TGF-β signalling attenuated Panc-1 cells showed S-phase arrest by direct activation of p27. However, Gatifloxacin mediated G₂–phase cell cycle arrest was found to be p53 dependent in both the cell lines. Our study is of interest because fluoroquinolones have the ability to penetrate pancreatic tissue which can be very effective in combating pancreatic cancers that are usually associated with loss or downregulation of CDK inhibitors p21/p27 as well as mutational inactivation of p53. Additionally, Gatifloxacin was also found to synergize the effect of Gemcitabine, the only known drug against pancreatic cancer, as well as the broad spectrum anticancer drug cisplatin. Taken together our results suggest that Gatifloxacin possesses anticancer activities against pancreatic cancer and is a promising candidate to be repositioned from broad spectrum antibiotics to anticancer agent.