Overexpression of p27^(KIP1)induced cell cycle arrest in G_1 phase and subsequent apoptosis in HCC-9204 cell line

AIM We have previously reported that inducible over-expresaion of Bak may prolong cell cycle in G1 phase and lead to apoptosis in HCC-9204 cells. This study is to investigate whether p27KIP1 plays an important role in this process. MEHODS In order to elucidate the exact function of p27KIP1 in this process, a zinc inducible p27KIP1 stable transfectant and transient p27KIP1- GFP fusion transfectant were constructed. The effects of inducible p27KIP1 on cell growth, cell cycle arrest and apoptosis were examined in the mock, control pMD vector, and pMD-KIP1 transfected HCC-9204 cells. RESULTS This p27KIP1-GFP transfectant may transiently express the fusion gene. The cell growth was reduced by 35% at 48 h of p27KIP1 induction with zinc treatment as determined by trypan blue exclusion assay. These differences remained the same after 72 h of p27KIP1 expression, p27KIP1 caused cell cycle arrest after 24 h of induction, with 40% increase in G1 population. Prolonged p27KIP1 expression in this cell line induced apoptotic cell death reflected by TUNEL assay. Fourty-eight h and 72 h of p27KIP1 expression showed a characteristic DNA ladder on agarose gel electrophoresis.

Effect of 5-Aza-2'-deoxycytidine on the P16 tumor suppressor gene in hepatocellular carcinoma cell line HepG2

INTRODUCTIONHepatocellular carcinoma (HCC) is one of the mostcommon human malignancies worldwide[1,2], and isclosely associated with infection of HBV and HCVand contamination of aflatoxin B1[3-6]. Althoughthe molecular mechanisms of hepatocarcinogenesisremain poorly understood, an increasing number ofgenetic abnormalities have been recognized[7-10],for example, the p16 gene[11,12] the p53gene[13-18], the E-cadherin gene[19], and the c-mycgene[20].

细胞周期抑制蛋白p27的研究进展

p27基因位于人类染色体12p13,其编码的蛋白对cyclinsCDKs具有广泛的抑制活性,是细胞周期调控的抑制蛋白。它以化学剂量的方式调节细胞周期的进程,参与细胞的生长、分化等过程。对p27基因的发现、基因结构、对细胞周期和细胞分化的调控机制以及与肿瘤的关系作一介绍。

Expression of positive and negative regulators of cell cycle during wound healing

OBJECTIVE: To detect the expression of cell cycle positive regulators cyclin D(1), cyclin E, CDK(2), CDK(4) and negative regulators p21(cip1), p27(kip1), p16(ink4a) and p15(ink4b) during wound healing in rats. METHODS: Open wounds of full-thickness skin, diameter 1.8 cm, on rat backs were used as the wound model. Wound tissues were harvested on postwounding days 3, 5, 7, 9, 11, 14, 21 and 30. Ki67 expression in granulation tissue was detected by immunohistochemical assay. The patterns of the expression of cyclin D(1), cyclin E, CDK(2), CDK(4) and p21(cip1), p27(kip1), p16(ink4a), p15(ink4b) were detected by Western blot. RESULTS: Cell proliferation in granulation tissue took place predominantly within the first week after injury, with the proliferation peak occurring at postwounding day 5. There were no dramatic variations in the expression of cyclin D(1), CDK(2) and CDK(4) during wound healing. Up-regulated cyclin E was maintained from day 3 to 11 after injury, and then was down-regulated. No expression of p16(ink4a) and p15(ink4b) was found. p21(cip1) was expressed only from day 7 to 14, with peak expression observed on day 9. Constitutive p27(kip1) was expressed throughout wound healing with low levels in the proliferating period of day 3 to 5 and with increased levels in the post-mitotic and remodeling stage. The expression of p21(cip1) and p27(kip1) showed an inverse gradient to that of Ki67. CONCLUSION: p21(cip1) and p27(kip1) play a supervising role in preventing the hyperproliferative tendency in tissue repair.

SKA2/FAM33A:A novel gene implicated in cell cycle,tumorigenesis,and psychiatric disorders

SKA2(spindle and KT associated 2),also referred to as FAM33A(family with sequence similarity 33,member A),is a recently identified gene involved in cell cycle regulation,and growing evidence is implicating its roles in tumorigenesis and psychiatric disorders.It has been demonstrated that SKA2,along with its coworkers SKA1 and SKA3,constitutes the SKA complex which plays a critical role in the maintenance of the metaphase plate and/or spindle checkpoint silencing during mitosis.SKA2 is over-expressed both in cancer cell lines and clinical samples including small cell lung cancer and breast cancer,whereas downregulation of SKA2 is associated with depression and suicidal ideation.The expression of SKA2 is regulated by transcription factors including NF-kB and CREB,miRNAs as well as DNA methylation.In this review,we provide an overview of studies that reveal SKA2 gene and protein characteristics as well as physiological function,with a special focus on its transcription regulatory mechanisms,and also provide a summary regarding the translational opportunity of the SKA2 gene as a clinical biomarker for cancers and psychiatric disorders.

The effect of adenovirus expressing wild-type p53 on 5-fluorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

AIM:There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU). Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53 gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status. METHODS:Human pancreatic cancer cell lines Capan-1^(p53mut), Capan-2^(p53wt),FAMPAC^(p53mut),PANC1^(p53mut),and rat pancreatic cancer cell lines AS^(p53wt) and DSL6A^(p53null) were used for in vitro studies.Following infection with different ratios of Ad- p53-particles (MOI) in combination with 5-FU,proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining).In addition,DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies. Tumor size,apoptosis (TUNEL) and survival were determined. RESULTS:Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53.In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU.Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU. CONCLUSION:Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function.These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

miR-505-5p在膀胱癌细胞中靶向调控PLK1抑制细胞增殖和迁移

目的探究miR-505-5p在膀胱癌细胞中对细胞增殖和迁移能力的影响。方法用qRT-PCR在膀胱癌及癌旁正常组织(n=18)中检测miR-505-5p和Polo样激酶1(Polo-like-kinase 1,PLK1)的表达量。用生物信息学预测miR-505-5p和PLK1的靶向匹配关系,并用双荧光素酶报告基因实验验证。在膀胱癌细胞中用Lipo3000转染miR-505-5p模拟物和抑制剂后,Western blot法检测PLK1蛋白表达;CCK-8法检测细胞增殖;Transwell法检测细胞迁移。结果 miR-505-5p在膀胱癌组织中低表达,PLK1在膀胱癌组织中高表达,与癌旁正常组织比较,差异均具有统计学意义(均P<0.01)。miR-505-5p能与PLK1 mRNA 3′-非翻译区结合,并抑制其表达。上调miR-505-5p,PLK1蛋白水平降低,细胞增殖能力下降,迁移减弱,与对照组比较,差异均具有统计学意义(均P<0.05)。结论 miR-505-5p通过靶向作用于PLK1 mRNA 3′-UTR负向调控PLK1的表达及负向调控细胞增殖和迁移。

P^(27)的研究概况

目的 :综述P27的研究进展。方法 :光盘检索有关文献 ,归纳综合整理。结果 :P27是细胞周期的相关蛋白 ,P27蛋白过度表达可抑制细胞周期的进程 ,阻断细胞生长于G1 期。结论 :P27是细胞周期中重要的负性调控因子 。

软骨肉瘤中P^(27)和P^(16)蛋白表达的临床意义

目的：探讨P27和P16表达对软骨肉瘤诊断，分级和预后的临床意义。方法：分析P27和P16蛋白表达与良、恶性软骨肿瘤和软骨肉瘤病理分级间以及与软骨肉瘤不同临床病理因素间的关系。结果：①P27和P16表达与软骨肉瘤组织学分级显著相关（P＜0．05）。②P27表达在良、恶性软骨肿瘤间及Ⅰ级软骨肉瘤和软骨瘤间差异均有显著性（P＜0．05）。③P27和P16表达在软骨肉瘤体积，复发方面差异有显著性（P＜0．05）。结论：①P27蛋白表达可能作为软骨肉瘤诊断和鉴别诊断标记物。②P27和P16蛋白表达对软骨肉瘤组织学分级，恶性进展和预后判断有指导意义。

P^(27)、cyclinE在子宫内膜腺癌中的表达及其意义

应用免疫组化SP法检测12例正常子宫内膜、41例子宫内膜增殖症(其中14例单纯型增生,19例复合型增生,8例不典型增生)、45例子宫内膜腺癌组织中P^(27)、细胞周期素(cyclinE)的表达情况。结果显示,P^(27)在正常子宫内膜、子宫内膜增殖症和子宫内膜腺癌中表达率分别为100.0％、65.9％、42.2％,三者差异有显著性(P<0.05);在单纯型增生(SH)、复合型增生(CH)、不典型增生(AH)中的表达率分别为85.7％、68.4％、25.0％,SH与AH差异有显著性(P<0.05)。。cyclinE在正常子宫内膜、子宫内膜增殖症和子宫内膜腺癌中的表达率分别为0、26.8％和73.3％,前两者与后者差异均有显著性(P<0.05);在SH、CH和AH中的表达率分别为7.1％、26.3％、62.5％,SH与AH差异有显著性(P<0.05)。认为子宫内膜腺癌组织中P^(27)与cyclinE蛋白表达存在负相关,P^(27)蛋白缺乏、cyclinE蛋白过表达引起的细胞周期失控与子宫内膜腺癌发生密切相关。

多聚腺苷酸结合蛋白相互作用蛋白1与肿瘤关系的研究进展

多聚腺苷酸结合蛋白相互作用蛋白1[Poly(A)-binding protein-interacting protein 1,Paip1]是哺乳动物特有的蛋白质,可有效参与真核生物基因表达及细胞周期调控,并与肿瘤演进及预后密切相关。近年来Paip1成为肿瘤研究热点,Paip1与肿瘤细胞增殖、迁移、侵袭和上皮间质转化进程密切相关,可能是肿瘤进展及预后不良的潜在生物标志和新的治疗靶点。但其具体作用机制尚未阐明。本文就Paip1的结构、功能、泛素化和降解及其与肿瘤的关系等方面作一综述,为其在肿瘤中的研究提供新思路。

Ska2/FAM33A:一个参与细胞周期调控与肿瘤发生的新基因

Ska2(spindle and KT associated 2),也称FAM33A(family with sequence similarity 33,member A),是一个最近鉴定的参与细胞周期调控与肿瘤发生发展的新基因。现有研究初步证实,Ska2参与组成Ska复合体,在有丝分裂中期纺锤体检验点关闭中起重要作用;Ska2在小细胞肺癌和乳腺癌中呈现表达上调,可通过糖皮质激素受体等途径参与细胞增殖调节和肿瘤发生发展;NF-κΒ和CREB等转录因子可能参与Ska2的表达调控。Ska2有望成为一个恶性肿瘤诊断和靶向治疗的新靶点。