Accumulation of cell cycle regulatory proteins,p21 and p27, induced after hyperthermia in human glioma cells

It was investigated whether there was a relationship between p53 p21 and p27 induction pathways in the cellular response of glioma cells to hyperthermia. Two glioma cell lines were employed. A-172 cells had the wild-type of p53, and U251 cells had the mutant-type of p53. An adenovirus harbouring wild-type p53 was also used for the overexpression. The protein induction by hyperthermia was monitored by Western blot analysis. In U251 cells, the expression of wild-type p53 and hyperthermia had an additional cytotoxic effect, but did not affect A-172 cells. Significant p21 accumulation by hyperthermia was recognized in A-172 cells, and was also recognized in p53-transduced U251 cells. On the other hand, the accumulation of p27 by hyperthermia was not seen in A-172 or U251 cells, and the exogenous expression of p53 did not affect the accumulation of p27 by hyperthermia in U251 cells. These findings suggest that the p53 p21 pathway is involved in the signal transduction after hyperthermia, rather than the p27 pathway.     

Accumulation of cell cycle regulatory proteins, p21 and p27, induced after hyperthermia in human glioma cells.

It was investigated whether there was a relationship between p53 p21 and p27 induction pathways in the cellular response of glioma cells to hyperthermia. Two glioma cell lines were employed. A-172 cells had the wild-type of p53, and U251 cells had the mutant-type of p53. An adenovirus harbouring wild-type p53 was also used for the overexpression. The protein induction by hyperthermia was monitored by Western blot analysis. In U251 cells, the expression of wild-type p53 and hyperthermia had an additional cytotoxic effect, but did not affect A-172 cells. Significant p21 accumulation by hyperthermia was recognized in A-172 cells, and was also recognized in p53-transduced U251 cells. On the other hand, the accumulation of p27 by hyperthermia was not seen in A-172 or U251 cells, and the exogenous expression of p53 did not affect the accumulation of p27 by hyperthermia in U251 cells. These findings suggest that the p53-p21 pathway is involved in the signal transduction after hyperthermia, rather than the p27 pathway.     

As2O3对人膀胱癌细胞凋亡和MDR1表达及细胞周期的影响

目的 :观察三氧化二砷 (As2 O3 )对人膀胱癌细胞株BIU 87的凋亡诱导作用及对多药耐药基因 (MDR1)蛋白表达、细胞周期的影响。方法 :采用四氮唑蓝 (MTT)法检测As2 O3 不同浓度、不同作用时间对BIU 87细胞的生长抑制率 ;流式细胞术(FCM )检测不同浓度As2 O3 作用 72h后细胞中与凋亡有关蛋白Fas、bcl 2及MDR1蛋白表达、细胞周期变化。结果 :As2 O3 可有效抑制BIU 87细胞的生长增殖 ,与浓度、时间相关 ,P <0 0 5 ;Fas、bcl 2的表达分别与浓度增高呈正、负相关 ,P <0 0 5 ,且二者随浓度增高呈负相关 ,P <0 0 5 ;MDR1蛋白表达与对照组相比As2 O3 1μmol/L作用后升高 ,P <0 0 5 ,2、5 μmol/L作用后降低 ,P <0 0 5 ;随As2 O3 浓度升高 ,细胞周期被阻滞在G0 /G1期。结论 :As2 O3 可有效抑制人膀胱癌细胞的生长增殖 ,诱导细胞凋亡及阻滞细胞周期可能起了重要作用     

三氧化二砷对人肺癌细胞株增殖和凋亡的影响

目的 探讨三氧化二砷（Ａｓ２Ｏ３）对人肺癌的潜在性治疗作用及可能的机制。方法 选用人肺癌细胞株ＧＬＣ－８３,运用细胞培养法、ＭＴＴ法、流式细胞术（ＦＣＭ）检测细胞生长曲线、细胞增殖、细胞周期和细胞凋亡。结果 三氧化二砷可明显抑制ＧＬＣ－８２细胞的增殖,其抑制作用具有时－效和量－效关系。当４．０μｍｏｌ／Ｌ三氧化二砷处理ＧＬＣ－８２细胞９６小时,增殖抑制率达８１．０５％,ＦＣＭ检测肿瘤细胞ＤＮＡ含量,观察到三氧化二砷ＧＬＣ－８２细胞周期阻滞于Ｇ２／Ｍ期,细胞周期进程变慢,同时出现剂量依赖性Ｇ１峰。结论 三氧化二砷能有效地抑制人肺癌细胞株ＧＬＣ－８２的增殖,其可能的机制与三氧化二砷使细胞阻滞于Ｇ２／Ｍ期并诱导其调亡有关。     

亚砷酸诱导人鼻咽癌细胞中p16基因表达的研究

目的 研究亚砷酸( As2O3)诱导鼻咽癌(nasopharyngeal carcinoma,NPC)CNE- 2Z细胞株中抑癌基因p16的表达.方法 体外培养的CNE-2Z细胞分别加入不同浓度的亚砷酸,并作用于不同时间.用终浓度为2μmol/L、1 μmol/L、0.5μmol/L的As2O3加入鼻咽癌CNE-2...     

p21和p27基因多态性与非小细胞肺癌的相关性研究

目的：探讨p21和p27基因多态性与非小细胞肺癌（NSCLC）遗传易感性的关系。方法：应用聚合酶链反应-限制性片段长度多态性分析（PCR—RFLP）方法,分析202例NSCLC患者和265名健康对照人群p21基因3’非翻译区（3’UTR）和p27基因第109密码子多态性位点的基因型。结果：p21基因3’UTR突变型（C／T＋T／T）频率在病例组（72．8％）显著高于对照组（63．8％）,X^2=4．24,P=0．039。携带C／T和T／T基因型可显著增加这一人群NSCLC发病风险（经性别、年龄校正的OR=1．54,95％CI为1．03～2．30）。分层分析发现,p21基因突变型（C／T＋T／T）频率在不吸烟病例组（81．6％）和≥50岁病例组（73．1％）均显著高于对照组,携带C／T和T／T基因型可显著增高不吸烟者和≥50岁人群的NSCLC发病风险（经性别、年龄校正的OR分别为2．78和1．72,95％C1分剐为1．38～5．63和1．09～2．71）。p27基因型总体分布和分层分析在病例组和对照组差异无统计学意义。结论：p21基因3’UTR多态性可能与NSCLC的发病风险有关。p27基因多态性与NSCLC遗传易感性无关。     

三氧化二砷抑制小鼠H22肝癌移植瘤血管生长的实验研究

目的：探讨三氧化二砷（As2O3）对小鼠H22肝癌移植瘤组织血管生成的抑制作用。方法：建立小鼠H22肝癌移植瘤模型，腹腔应用As2O3治疗后，通过瘤体体积及瘤重的比较，病理观察血管分布，VEGF及bFGF免疫组化检测，反映As2O3对小鼠H22肝癌组织血管生成的抑制作用。结果：As2O3高剂量及低剂量组均有效地抑制荷瘤鼠皮下肿瘤的体积及瘤重，瘤重抑瘤率分别为39．32％、44．89％，病理观察发现As2O3治疗组的肿瘤血供较对照组明显减少，免疫组化检测结果为As2O3治疗组肿瘤细胞的VEGF阳性细胞数低于对照组VEGF阳性细胞数，As2O3治疗组bFGF阳性表达率明显低于对照组（P〈0．01），有显著差异。结论：As2O3对小鼠肝癌移植瘤血管生成具有明显的抑制作用，具有治疗肝癌的潜在价值。     

Induction of apoptosis and inhibition of human gastric cancer MGC-803 cell growth by arsenic trioxide

Arsenic trioxide (As2O3), used to treat human diseases for centuries in traditional Chinese medicine, has been identified as a very effective antileukaemic agent, but its effect on solid tumours which could be more suitable for clinical treatment with arsenic compounds is still unknown. In this study, we investigated the in vitro effect of As2O3 at concentrations of 0.01-1 microM against six human malignant cell lines, MGC-803, HIC, MCF-7, HeLa, BEL-7402 and A549 cells. As2O3 inhibited growth and induced apoptosis in these malignant cells at varying degrees, in a time dose-dependent manner. The most marked effects were seen in the gastric cancer cell line, MGC-803. In contrast, minimal growth inhibition and induction of apoptosis occurred in human embryonic pulmonary cells following treatment with As2O3 found at the same concentrations. Changes in intracellular Ca2+, following As2O3 treatment were measured by Ca2+ sensitive fluorescent probe Indo-1/AM in flow cytometric assays. The increase in intracellular Ca2+ correlated with the sensitivity of these cells to As2O3, possibly indicating that a critical intracellular Ca2+ signal transduction pathway could be involved in As2O3-mediated cell-death and its selectivity. The marked sensitivity of MGC-803 cells in vitro suggests that As2O3 may be a potential antigastric cancer agent.     

Exogenous expression of H-cadherin in CHO cells regulates contact inhibition of cell growth by inducing p21 expression

The impact of the cadherins in human cancers is becoming better understood. However, few studies have directly tested the hypothesis that H-cadherin, a tailless cadherin, is actually a tumor suppressor, and no published studies have addressed the question of how H-cadherin suppresses cellular transformation. We report here the influence that exogenous expression of H-cadherin imposes on growth, morphology, clonogenicity and tumorigenicity of Chinese hamster ovarian (CHO) cells. H-cadherin expression in CHO cells resulted in tighter adhesion of multicellular aggregates and reduced cell proliferation. In addition to enhancement of cell-cell adhesion, exogenous H-cadherin expression also inhibited cell proliferation and the ability to form colonies in soft agar. Furthermore, expression of H-cadherin in CHO cells led to complete suppression of subcutaneous tumor growth in nude mice. Seeding the H-cadherin expressing CHO cells on culture plates coated with recombinant H-cadherin amino-terminal fragments resulted in inhibition of cell proliferation that was accompanied by increased expression of the cdk inhibitor p21. These results support the role of H-cadherin as a tumor suppressor participating in contact inhibition of cell growth, possibly by inducing p21 expression.     

Vitamin D analogues up-regulate p21 and p27 during growth inhibition of pancreatic cancer cell lines.

To obtain information regarding the growth-inhibitory effect of 1,25-dihydroxyvitamin D3 and its non-calcaemic analogue 22-oxa-1,25-dihydroxyvitamin D3 on pancreatic cancer cell lines, differences in the effects of G1-phase cell cycle-regulating factors were studied in vitamin D-responsive and non-responsive cell lines. Levels of expression of cyclins (D1, E and A), cyclin-dependent kinases (2 and 4) and cyclin-dependent kinase inhibitors (p21 and p27) were analysed by Western blotting after treatment with these compounds. In the responsive cells (BxPC-3, Hs 700T and SUP-1), our observations were: (1) marked up-regulation of p21 and p27 after 24 h treatment with 10(-7) mol l(-1) 1,25-dihydroxyvitamin D3 and 22-oxa-1,25-dihydroxyvitamin D3; and (2) marked down-regulation of cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors after 7 days'' treatment. In non-responsive cells (Hs 766T and Capan-1), no such changes were observed. In conclusion, vitamin D analogues up-regulate p21 and p27 as an early event, which in turn could block the G1/S transition and induce growth inhibition in responsive cells.     

Cell cycle regulating proteins p21 and p27 in prognosis of oral squamous cell carcinomas

Cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDKIs), such as p21 and p27, exert a direct control on the cell cycle. p21 and p27 are negative regulators of cyclin-dependent kinases and in this function they are negative check-point regulators of the cell cycle. We therefore aimed to evaluate p21 and p27 expression in oral squamous cell carcinomas (OSSC) to determine the value as a prognostic marker. One hundred and ninety-two patients with histologically proven, surgically treated squamous cell carcinoma of the oral cavity were eligible for the study and investigated for the expression of p21 and p27 by means of tissue microarrays (TMAs). Immunohistochemical screening under identical condition were carried out with antibodies against p21 and p27. Correlations between clinical features and the expression of the respective antibodies were evaluated statistically by Kaplan-Meier curves, log-rank and chi(2) tests. The expression of p21 correlated significantly with an increased prognosis in the log-rang test (p=0.01). No significant correlation was found between the expression of p27 and the overall survival rate. In multivariate Cox analysis, p27 was indicated as independent predictor of survival prognosis in the subgroup of nodal positive carcinomas, p27 positive tumours showed a significantly better survival prognosis (p=0.03). p21 and p27 in carcinoma of oral cavity seem to be predictive parameter in regulation and prognosis of squamous cell carcinomas. A p21 negative subgroup of OSCC may benefit from additional radio or radiochemotherapy.     

Caffeic acid phenethyl ester induced cell cycle arrest and growth inhibition in androgen-independent prostate cancer cells via regulation of Skp2, p53, p21Cip1 and p27Kip1

Prostate cancer (PCa) patients receiving the androgen ablation therapy ultimately develop recurrent castration-resistant prostate cancer (CRPC) within 1–3 years. Treatment with caffeic acid phenethyl ester (CAPE) suppressed cell survival and proliferation via induction of G1 or G2/M cell cycle arrest in LNCaP 104-R1, DU-145, 22Rv1, and C4–2 CRPC cells. CAPE treatment also inhibited soft agar colony formation and retarded nude mice xenograft growth of LNCaP 104-R1 cells. We identified that CAPE treatment significantly reduced protein abundance of Skp2, Cdk2, Cdk4, Cdk7, Rb, phospho-Rb S807/811, cyclin A, cyclin D1, cyclin H, E2F1, c-Myc, SGK, phospho-p70S6kinase T421/S424, phospho-mTOR Ser2481, phospho-GSK3α Ser21, but induced p21^Cip1, p27^Kip1, ATF4, cyclin E, p53, TRIB3, phospho-p53 (Ser6, Ser33, Ser46, Ser392), phospho-p38 MAPK Thr180/Tyr182, Chk1, Chk2, phospho-ATM S1981, phospho-ATR S428, and phospho-p90RSK Ser380. CAPE treatment decreased Skp2 and Akt1 protein expression in LNCaP 104-R1 tumors as compared to control group. Overexpression of Skp2, or siRNA knockdown of p21^Cip1, p27^Kip1, or p53 blocked suppressive effect of CAPE treatment. Co-treatment of CAPE with PI3K inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 or Bcl-2 inhibitor ABT737 showed synergistic suppressive effects. Our finding suggested that CAPE treatment induced cell cycle arrest and growth inhibition in CRPC cells via regulation of Skp2, p53, p21^Cip1, and p27^Kip1.     

三氧化二砷对卵巢癌细胞的放射增强作用

目的：探讨三氧化二砷（As2O3）联合放射肿瘤细胞杀灭的影响，方法：以人卵巢癌细胞SKOV－3为实验对象，用四氮唑盐（MTT）比色法和流式细胞仪磷酯酰丝氨酸Ⅴ／PI双重染色法观察不同浓度As2O3与放射联合和单纯As2O3对SKOV－3的杀伤和诱导凋亡作用。采用成克隆分析法观察5mol/L As2O3的放射增强作用。结果：（1）细胞生长抑制随着As2O3剂量的增加而增强；（2）As2O3＋放射组的细胞存活率均低于单纯As2O3组，但随着As2O3剂量的加大，放射组和未放射组的存活率越来越接近；（3）在2Gy下，随着As2O3剂量的加大，凋亡的比例增加；（4）细胞存活曲线显示，放射＋As2O3组的Dq值小于单纯照射组（1．44Gy，2．78Gy），D0值也小于单纯照射组（0．85Gy，1．30Gy，SF2也小于单纯照射（0．42，0．87），根据D0值求出的增强比为1．53，根据SF2求出的增强比为2．07。结论As2O3在临床应用剂量范围内，与常规分割剂量放射治疗联合时，有望对肿瘤有较好的放射增强作用。     

Induction of cell cycle arrest and p21(CIP1/WAF1) expression in human lung cancer cells by isoliquiritigenin

Isoliquiritigenin is a natural flavonoid isolated from licorice, shallot and bean sprouts. The effect of isoliquiritigenin on cell proliferation and cell cycle progression was examined in the A549 human lung cancer cell line. Isoliquiritigenin significantly inhibited the proliferation of lung cancer cells in a dose- and time-dependent manner. Flow cytometric analysis demonstrated that isoliquiritigenin restrained the cell cycle progression at G2/M phase. Further examinations using cDNA arrays and real-time quantitative RT-PCR revealed that isoliquiritigenin enhanced the expression of p21(CIP1/WAF1), a universal inhibitor of cyclin-dependent kinases. These results suggest that isoliquiritigenin will be a promising agent for use in chemopreventive or therapeutics against lung cancer.     

A lipid-soluble iron chelator alters cell cycle regulatory protein binding in breast cancer cells compared to normal breast cells

The lipid-soluble iron chelator desferri-exochelin (D-Exo) causes reversible cell cycle arrest in normal human mammary epithelial cells (NHMEC) but triggers apoptotic cell death in human breast cancer cells. We studied the effects of iron chelation with D-Exo on cell cycle regulatory proteins in cultures of NHMEC and MCF-7 breast cancer cells. In co-immunoprecipitation studies, D-Exo inhibited binding of cyclins A and E to cyclin dependent kinase 2 (CDK2) in NHMEC, but in MCF-7 cells binding of these cyclins to CDK2 was enhanced. D-Exo treatment markedly increased expression of p53 and increased binding of p21 to CDK2 in the MCF-7 cells but not in NHMEC. Therefore differences in effects of iron chelation on cell cycle protein binding in cancer cells compared to normal cells may trigger apoptosis in cancer cells while normal breast cells are spared.     

Arsenic trioxide causes redistribution of cell cycle, caspase activation, and GADD expression in human colonic, breast, and pancreatic cancer cells

Arsenic trioxide is valuable for treatment of promyelocytic leukemia, but less attention has been paid to its therapeutic potential for other cancers. In this study, the effects of arsenic trioxide were tested in human pancreatic (AsPC-1), colonic (HT-29), and breast (MCF-7) cancer cells. In all three cancer cell lines, arsenic trioxide inhibited proliferation in a concentration and time-dependent manner, as measured by ³H-methyl thymidine incorporation and cell counting. Coincident with inhibition of growth, arsenic trioxide induced marked morphologic changes, including reduced cytoplasmic volume, membrane blebbing, and nuclear condensation consistent with apoptosis. Propidium iodide DNA staining at 24 hours revealed cell cycle arrest in the G0/G1 phase and an increase in the S phase, while at 72 hr there was G2/M phase arrest with a marked increase in the sub-G0/G1, apoptotic cell population. The DNA fragmentation induced by arsenic trioxide was confirmed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay in all cell lines. Western blot analysis revealed activation of caspase -3, -7, and -9 by arsenic trioxide. Caspase-3 activity was confirmed by demonstrating cleavage of its downstream target, poly ADP-ribose polymerase (PARP). Expression of the antiapoptosis protein, Bcl-2, was time-dependently decreased. In contrast, arsenic trioxide markedly enhanced the expression of the p21 protein, GADD45 and GADD153, in a time-dependent manner. These findings suggest that arsenic trioxide has potential as a therapeutic agent for these cancers.     

Berberine enhances inhibition of glioma tumor cell migration and invasiveness mediated by arsenic trioxide

Background  

Arsenic trioxide (As₂O₃) exhibits promising anticarcinogenic activity in acute promyelocytic leukemic patients and induces apoptosis in various tumor cells in vitro. Here, we investigated the effect of the natural alkaloid berberine on As₂O₃-mediated inhibition of cancer cell migration using rat and human glioma cell lines.