Inhibition of cell proliferation in head and neck squamous cell carcinoma cell lines with antisense cyclin D1

Cyclin D1 and cyclin G are essential regulatory factors in the progression of the cell cycle from G0 through G1 and S phase. Aberrations in expression of these cyclins may lead to dysregulated cellular proliferation that could result in neoplasia. Amplification and overexpression of cyclin D1 have been observed in many human cancers, whereas cyclin G is a new cyclin recently described in osteosarcoma cells. This study was performed to determine whether these cyclins were amplified in head and neck squamous cell carcinoma (HNSCC) tumors. Polymerase chain reaction of DNA extracted from 22 HNSCC primary tumors and three HNSCC cell lines did not reveal amplification of cyclin D1 in any of the tumor samples. Southern blot analysis identified amplification of cyclin D1 in a single tumor. Amplification of cyclin G was not observed in any of the tumors by Southern blot hybridization with a cyclin G probe. HNSCC cell lines transfected with antisense cyclin D1 were tested for cell proliferation by the incorporation of ³ H-thymidine into cells grown in serum-free media. By 72 hours of incubation, there was a greater than 30% reduction in proliferation of cells transfected with antisense cyclin D1 as compared with nontransfected control cells. The results indicate that cyclin D1 may play an important role in the growth and proliferation of HNSCC cells. (Otolaryngol Head Neck Surg 1998;119:593-9.)     

Intestinal cell cycle regulations. Interactions of cyclin D1, Cdk4, and p21Cip1.

OBJECTIVE: The p21Cip1 protein is a potent stoichiometric inhibitor of cyclin-dependent kinase activity, and p21Cip1 mRNA expression is localized to the nonproliferative compartment of the intestinal villus, suggesting an in vivo growth-inhibitory role in the gut. The authors determined whether nontransformed rat intestinal epithelial cells (IECs) underwent reversible cell cycle arrest by contact inhibition, and determined whether increases in the relative amount of p21 associated with cyclin D/Cdk4 protein complexes were associated with cell growth arrest. METHODS: Density arrest was achieved by prolonged culture IEC-6 in confluent conditions (5 or more days). Release from density arrest was achieved by detaching the cells from the culture plate and reseeding them at a 1:4 ratio. The DNA synthesis was estimated by [3H]-thymidine incorporation and expressed as mean plus or minus standard error of the mean (n = 4). Cyclin D1, Cdk4, and p21 mRNA and protein levels were determined by standard Northern and Western blot analyses, respectively. Cyclin D1, Cdk4, and p21 protein complex formation was analyzed by immunoprecipitating the complexes from cell lysates with an antibody to one of the constituents, followed by SDS polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis of the precipitated complexes using antibodies to the other proteins. The kinase activity of the immunoprecipitated Cdk4 was determined using recombinant Rb as substrate. RESULTS: The IEC-6[3H]-thymidine incorporation was decreased 7.5-fold from day 1 confluence to day 7 of confluence. Twenty-four hours after release from density arrest, there was a 43-fold increase in [3H]-thymidine incorporation. Cyclin D1 and Cdk4 mRNA levels remained relatively constant during contact inhibition, whereas immunoblotting showed that the levels of cyclin D1 and Cdk4 proteins decreased by 70.9% and 68.7%, respectively, comparing day 3 with day 9 during density arrest. The levels of cyclin D1 increased 5.8-fold and Cdk4 increased by 4.4-fold by 24 hours after reseeding the day 9 density-arrested cultures, coincident with the increase in DNA synthesis. The amount of p21 associated with the cyclin D1 and Cdk4 complex in the density-arrested cells was 170% of that observed in the reseeded, proliferating cells. More important, the p21::Cdk4 ratio was 6.4-fold higher in the density-arrested (quiescent) cells as compared with rapidly proliferating cells by 24 hours after release from growth arrest. Recovery of Cdk4-dependent kinase activity occurred by 4 hours after release from growth arrest, coincident with decreased binding of p21 to the complex. CONCLUSIONS: Intestinal epithelial cells in culture can undergo density-dependent growth arrest. This process involves downregulation of cyclin D1 and Cdk4 at the level of protein expression, whereas the mRNA levels remain relatively unchanged. Further, during contact inhibition, there is more p21 associated with cyclin D1/Cdk4, which further contributes to the inhibition of the kinase complex. The authors also have shown that the process of contact inhibition is reversible, which may explain partly the ability of the intestinal epithelium to increase proliferative activity in response to injury.     

热打击对培养肠黏膜上皮细胞IEC-6细胞活性和增殖的影响

目的：研究梯度热打击对体外培养肠黏膜上皮细胞活性和增殖的影响。方法：肠黏膜上皮细胞株IEC-6经培养后分为正常对照组（37℃、5％CO2培养箱培养）及39℃、41℃、43℃热打击组（分别在相应温度培养箱中培养）,相差显微镜观察各组细胞培养1h的形态学改变,CCK8法比较各组细胞培养0、1、3、5、7h的细胞活性和24h增殖率,流式细胞术研究细胞周期的改变。结果：与正常对照组比较,各热打击组各个时相细胞形态变圆,伪足变短,细胞间隙增大,活力下降（P〈0．01）。24h细胞增殖实验显示,与正常对照组比较,39℃组7h及41℃和43℃组各时相增殖率显著下降（P〈0．01）,呈时间及温度依赖关系。流式细胞术检查显示,热打击组细胞呈现细胞周期G0／G1和G2／M期阻滞。结论：热打击对IEC-6细胞具有细胞毒效应,可抑制IEC-6细胞的增殖,造成细胞周期G0／G1和G2／M期阻滞。     

胰高血糖素样肽-2对烧伤大鼠肠粘膜细胞增殖的影响

目的　探讨胰高血糖素样肽 2 (GLP 2 )对烧伤大鼠肠粘膜细胞增殖及肠粘膜结构的影响。　方法　 5 5只Wistar大鼠随机分为烧伤组、GLP 2组 (烧伤后经GLP 2处理 ,2 0 0 μg/kg ,2次 /d腹腔注射 )与正常对照组。前两组动物于 30 %TBSAⅢ度烧伤后 6、12h及 1、3、5d分别处死 ,另处死正常对照组大鼠。检测各组增殖细胞核抗原 (PCNA)、细胞周期蛋白CyclinD的表达情况以及血浆二胺氧化酶 (DAO)的活性 ,并行肠粘膜组织学观察。　结果　与正常对照组比较 ,烧伤组伤后 6、12hPCNA表达稍有增强 ,伤后 1d减弱 ,3d时最低 ,5d时仍低于正常 ;GLP 2组PCNA表达的变化在伤后早期与烧伤组基本一致 ,但伤后 3、5d时强于烧伤组。烧伤组大鼠肠粘膜CyclinD蛋白在伤后 6、12h略有升高 ,但 1d时迅速下降至伤前的 4 0 % ,而GLP 2组CyclinD蛋白表达在伤后 1、3、5d高于烧伤组。大鼠烧伤后血浆DAO活性明显升高 ,经GLP 2治疗 5d后该指标明显降低 (P <0 .0 1)。组织学观察见GLP 2组肠绒毛排列较为规则 ,长短较一致 ,未见明显的上皮脱落。　结论　大鼠烧伤后腹腔给予外源性GLP 2能减轻肠粘膜损伤 ,其机制可能与GLP 2使PCNA、ClyclinD表达增加、促进受损肠粘膜细胞增殖有关。     

Mechanisms involved in resveratrol-induced apoptosis and cell cycle arrest in prostate cancer-derived cell lines

Resveratrol is a polyphenol found at high concentrations in grapes and red wine with reported anticarcinogenic effects. We studied the molecular mechanism of resveratrol-induced apoptosis and proliferation arrest in prostate derived cells PZ-HPV-7 (nontumorigenic line), LNCaP (androgen-sensitive cancer line), and PC-3 (androgen-insensitive cancer line). Apoptosis and cell cycle distribution were evaluated by flow cytometry and proliferation by MTT assay and direct cell counting. Caspases, bax, bcl-2, cyclins, Cdks, p53, p21, and p27 were measured by Western blot and kinase activities of cyclin/Cdk complexes by immunoprecipitation followed by kinase assays with appropriate substrates. Resveratrol induced a decrease in proliferation rates and an increase in apoptosis in cancer cell lines in a dose- and time-dependent manner. These effects were coincident with cell accumulation at the G0/G1 phase. In LNCaP and PC-3, the apoptosis induced by resveratrol was mediated by activation of caspases 9 and 3 and a change in the ratio of bax/bcl-2. Expressions of cyclin D1, E, and Cdk4 as well as cyclin D1/Cdk4 kinase activity were reduced by resveratrol only in LNCaP cells. In contrast, cyclin B and Cdk1 expression and cyclin B/Cdk1 kinase activity were decreased in both cell lines in the presence of resveratrol. However, modulator proteins p53, p21, and p27 were increased by resveratrol only in LNCaP cells. These effects probably result in the observed proliferation arrest and disruption of cell cycle control. In addition, the specific differences found between LNCaP and PC-3 suggest that resveratrol acts through different mechanisms upon the androgen or estrogen receptor cell status.     

Taurodeoxycholate increases intestinal epithelial cell proliferation through c-myc expression

BACKGROUND: Bile salts have been shown to modulate gastrointestinal epithelial restitution, differentiation, and other functions. Prior studies have shown that the bile salt taurodeoxycholate increases cell migration after injury. The purpose of this experiment was to determine the effect that taurodeoxycholate has on intestinal epithelial cell growth, c-myc expression and function. METHODS: IEC-6 or Caco-2 cells were treated with varying concentrations of taurodeoxycholate (.05 to 1 mmol/L) and proliferation determined. Apoptosis was measured by use of DNA fragmentation assay and nuclear staining. Cell phase was determined with propidium iodide flow cytometry. C-myc expression was determined by Northern and Western blot analysis, and c-myc function was inhibited by specific c-myc antisense. RESULTS: There was no change in cell structure. Apoptosis was not induced. Six days after exposure to taurodeoxycholate, IEC-6 cell proliferation was significantly increased. Flow cytometry showed a significant increase in S-phase concentration and a significant decrease in G1-phase concentration of the cell cycle. Taurodeoxycholate also increased c-myc protein and mRNA expression, and inhibition of c-myc function prevented taurodeoxycholate-induced cell proliferation. CONCLUSIONS: Exposure to physiological concentrations of the bile salt taurodeoxycholate increases intestinal epithelial cell proliferation. This effect is at least partially mediated through a c-myc-dependent mechanism. Bile salts can have a beneficial effect on the intestinal mucosa.     

Baohuoside-1 inhibits activated T cell proliferation at G(1)-S phase transition

BACKGROUND: The effect of baohuoside-1 (B1), a novel flavonoid, on cell proliferation and the cell cycle was evaluated in this study. METHODS: The antiproliferative properties of B1 were evaluated by proliferation assay. Western blotting and flow cytometric analysis were employed to investigate the expression of cyclins and cyclin-dependent kinase proteins. RESULTS: The major findings were (1) B1 effectively inhibited the cell proliferation activated by mitogenic antigen, with a 50% inhibitory concentration in low muM and in a dose- and time-dependent manner. (2) B1 resulted in G(1)-S phase cells arrest. (3) It down-regulated the expression of cyclin A, D and p33 cyclin-dependent kinase-2 (p33cdk2) proteins. (4) B1 suppressed the growth of several tumor cell lines. (5) B1 prevented rat heart allograft rejection in vivo. CONCLUSIONS: B1 immunosuppression of mitogen-activated T cell proliferation occurs in G(1)-S transition. It may be associated with the expression of cyclin A, D and p33cdk2 proteins. B1 prevents rat heart allograft rejection in vivo. The mechanism of B1 is different from tacrolimus and sirolimus.     

Role of keratinocyte growth factor in the pathogenesis of autosomal dominant polycystic kidney disease.

BACKGROUND: Previous studies have shown that the expression and distribution of keratinocyte growth factor (KGF), also known as FGF-7 (fibroblast growth factor-7) or HBGF-7 (heparin-binding growth factor-7), may be implicated in kidney cyst formation and expansion. However, there are no data on KGF expression in human autosomal dominant polycystic kidney disease (ADPKD) tissue, and it is unknown whether it affects ADPKD cyst-lining epithelial cell epithelial cell proliferation. METHODS: The expression and distribution of KGF and KGF receptor (KGFR) mRNA in ADPKD cystic and normal kidney tissues were examined using quantitative real-time polymerase chain reaction (PCR) and in situ hybridization. KGF and KGFR protein expression in the above tissues was analysed by immunohistochemistry and western blot. The effect of KGF on cyst-lining epithelial cell proliferation was assessed by MTT assay, and its effect on the cyst-lining epithelial cell cycle was analysed by flow cytometry. The effect of KGF on cyclin D1 and P21(wafl) gene expression in cyst-lining epithelial cells was also determined. RESULTS: KGF and KGFR mRNA expression in ADPKD cysts was higher than in normal kidney tissues. KGF and KGFR protein expression was also higher in ADPKD cysts and was localized to cyst-lining epithelial cells, tubular and interstitial cells. In vitro experiments revealed that KGF promoted cyst-lining epithelial cell proliferation, and decreased the ratio of G0/G1 phase but increased that of S phase. In response to KGF, the expression of the cyclin D1 gene in cyst-lining epithelial cells increased markedly while P21(wafl) expression decreased. CONCLUSIONS: KGF and KGFR expression was upregulated in ADPKD kidney tissues. KGF stimulated the proliferation of cyst-lining epithelial cell in vitro by regulating the expression of cyclin D1 and P21(wafl) genes. KGF may play a role in pathogenesis of ADPKD.     

TRIM55对大鼠系膜细胞增殖的调控作用

目的系膜增殖性肾炎是世界范围内高发的肾小球疾病,其发病与系膜细胞异常增殖有关,但调控系膜细胞增殖的内在分子机制尚不明确。本研究旨在探索TRIM55对大鼠系膜细胞(RMCs)增殖的调控作用及机制。 方法向8周龄雄性SD大鼠尾静脉注射2.5 mg/kg抗Thy-1抗体建立抗Thy-1肾炎模型。PAS染色观察肾脏病理表现,qPCR检测大鼠肾小球TRIM55 mRNA表达量;利用质粒及siRNA转染分别得到TRIM55过表达及低表达的RMCs,利用流式细胞仪检测其细胞周期;Western印迹检测p27及Cyclin D1的蛋白表达量。 结果TRIM55在抗Thy-1肾炎模型系膜增殖期高表达(P<0.01,T＝3.625)。体外RMCs中,TRIM55过表达可促进RMCs细胞周期由G1期向G2/S期转化,诱导系膜细胞增殖(P<0.01,T＝13.1);TRIM55低表达可引起RMCs的G1期阻滞,抑制RMCs增殖(P<0.01,T＝5.31)。此外,TRIM55过表达可下调p27表达、上调Cyclin D1;反之,TRIM55低表达可上调p27表达、下调Cyclin D1。 结论TRIM55可通过调节p27及Cyclin D1表达水平影响细胞由G1期到G2/S期的转化,进而调控RMCs的增殖。     

β-连环蛋白介导流体剪切力对成骨细胞增殖影响的实验研究

目的探讨β-连环蛋白(β-catenin)和细胞周期素D1(cyclinD1)在流体剪切力促进小鼠胚胎成骨细胞系MC3T3-E1细胞增殖过程中的作用。方法通过流体小室系统对体外培养成骨细胞爬片施加不同强度及时间梯度的流体剪切力,应用免疫荧光双标记法检测不同大小及时间流体剪切力作用下体外培养MC3T3-E1细胞中β-catenin及cyclinD1的表达;利用流式细胞技术检测增殖指数,分析β-catenin介导下流体剪切力对MC3T3-E1细胞G1→S期转化的影响。结果中等大小的流体剪切力(12dyn/cm2)作用下MC3T3-E1细胞中β-catenin及cyclinD1的表达较静置组、低应力组(6dyn/cm2)和高应力组(18dyn/cm2)明显增多(F=4.26,P=0.022;F=6.59,P=0.004),增殖指数也显著升高(F=5.84,P=0.037),且β-catenin与cyclinD1的表达呈正相关关系(r=0.65,P0.05)。结论流体剪切力通过引起β-catenin在胞浆内积聚,进而核转位发挥转录因子的作用,引起目标蛋白cyclinD1表达增加,在G1→S期转化过程中发挥了重要作用。中等大小的流体剪切力有显著促进细胞增殖作用。     

Prominent induction of cyclin B1 in G2/M renal cancer cells with butyrolactone 1

BACKGROUND: Butyrolactone 1 (BL) is a cyclin dependent kinase (CDK) inhibitor derived from Aspergillus terreus. None of the present drugs are effective for the treatment of renal cell carcinoma. The use of BL is expected to promote a new type therapy of renal cancer. METHODS: We investigated three human renal cancer cell lines: ACHN, OS-RC-2 and RCC10RGB, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and two-color flow cytometry. Simultaneous measurements of DNA content and cyclin expression allowed us to perform cell cycle specific analysis. Western blot analysis was performed using ACHN to represent cell lines. RESULTS: BL inhibited cell proliferation and caused cell accumulation at G2/M phase associated with the emergence of the third peak. Moreover, BL induced cyclin B1 over-expression in G2/M cells. These changes were quite definite, whereas cyclins D1, E and A showed no changes at all. Cyclin B1 accumulation was confirmed by western blot analysis. The chronological observation revealed that the emergence of the third peak preceded the regression of the increased cyclin B1 positive G2/M cells. These results suggested that BL accelerated cyclin B1 accumulation in G2/M cells, which then shifted to G1 phase without cell division. New G1 cells started DNA synthesis most likely as endoreduplication to form the third peak and the mechanism of cyclin B1 accumulation converted into down-regulation. CONCLUSION: BL induced significant cell kinetic interference in the tested human renal carcinoma cell lines. This might indicate the possibility of a new medical treatment modality for renal cancer.     

Cyclins and breast cancer

Recent advances in the understanding of cell cycle control by cyclins and cyclin-dependent kinases provide a basis for delineating the molecular mechanisms of proliferation control by steroids and the development and progression of hormone-dependent cancers. Cyclin D1 is necessary, rate-limiting and sufficient for G₁ progression in breast cancer cells and regulation of cyclin D1 expression or function is an early response to steroid and steroid antagonist regulation of proliferation. The cyclin D1 gene is amplified in 15%, and its product overexpressed in 40–50%, of primary breast carcinomas. The strong evidence that cyclin D1 plays a major role in cell cycle control in breast epithelial cells suggests that its deregulated expression may have effects on disease progression and phenotype including sensitivity to endocrine therapies.     

Osteoclast differentiation by RANKL requires NF-kappaB-mediated downregulation of cyclin-dependent kinase 6 (Cdk6).

This study investigated the involvement of cell cycle factors in RANKL-induced osteoclast differentiation. Among the G1 cell cycle factors, Cdk6 was found to be a key molecule in determining the differentiation rate of osteoclasts as a downstream effector of the NF-kappaB signaling. INTRODUCTION: A temporal arrest in the G1 phase of the cell cycle is a prerequisite for cell differentiation, making it possible that cell cycle factors regulate not only the proliferation but also the differentiation of cells. This study investigated cell cycle factors that critically influence differentiation of the murine monocytic RAW264.7 cells to osteoclasts induced by RANKL. MATERIALS AND METHODS: Growth-arrested RAW cells were stimulated with serum in the presence or absence of soluble RANKL (100 ng/ml). Expressions of the G1 cell cycle factors cyclin D1, D2, D3, E, cyclin-dependent kinase (Cdk) 2, 4, 6, and Cdk inhibitors (p18 and p27) were determined by Western blot analysis. Involvement of NF-kappaB and c-jun N-terminal kinase (JNK) pathways was examined by overexpressing dominant negative mutants of the IkappaB kinase 2 (IKK(DN)) gene and mitogen-activated protein kinase kinase 7 (MKK7(DN)) gene, respectively, using the adenovirus vectors. To determine the direct effect of Cdk6 on osteoclast differentiation, stable clones of RAW cells transfected with Cdk6 cDNA were established. Osteoclast differentiation was determined by TRACP staining, and cell cycle regulation was determined by BrdU uptake and flow cytometric analysis. RESULTS AND CONCLUSION: Among the cell cycle factors examined, the Cdk6 level was downregulated by RANKL synchronously with the appearance of multinucleated osteoclasts. Inhibition of the NF-kappaB pathway by IKK(DN) overexpression, but not that of the JNK pathway by MKK7(DN) overexpression, caused the decreases in both Cdk6 downregulation and osteoclastogenesis by RANKL. RAW cells overexpressing Cdk6 resist RANKL-induced osteoclastogenesis; however, cell cycle regulation was not affected by the levels of Cdk6 overexpression, suggesting that the inhibitory effect of Cdk6 on osteoclast differentiation was not exerted through cell cycle regulation. These results indicate that Cdk6 is a critical regulator of RANKL-induced osteoclast differentiation and that its NF-kappaB-mediated downregulation is essential for efficient osteoclast differentiation.     

不同营养支持途径对烧伤大鼠肠粘膜上皮细胞周期的影响

目的：探讨肠道喂养及静脉营养对烧伤早期肠粘膜上皮细胞周期的影响。方法：66只烧伤大鼠随机分为肠道喂养组（EF组）及静脉营养组（PN组），分别采用灌喂和颈外静脉输入方法给予等氮、等热卡的营养液。每组设伤后6、12、24、48、72h5个观察时相点，每时相点6只大鼠，并设正常对照（6只）。采用流式细胞技术进行空、回肠粘膜上皮细胞周期分析，以Western blot法检测肠粘膜细胞周期蛋白D1、E及细胞周期蛋白依赖性激酶（CDK）2、4的表达。结果：（1）肠粘膜上皮GO／G1期细胞百分比的变化：在空肠粘膜，伤后72h时EF组明显低于PN组（P＜0．05）；在回肠粘膜，6、12、48、72h时EF组与PN组比较，差异有显性意义（P＜0．05）；（2）伤后48．72h时EF组S期细胞百分比均显高于PN组（P＜0．05－0．01）；（3）肠粘膜细胞周期蛋白D1表达的变化：与对照值比较，EF组在伤后24h及PN组在伤后48h明显增高（P＜0．05），72h时EF组显高于PN组（P＜0．05）；（4）EF组肠粘膜细胞周期蛋白E的表达在伤后72h显高于对照值和PN组（P＜0．05）；（5）PN、EF组肠粘膜CDK2的表达与对照值比较以及PN、EF两组间比较，差异均无显性意义（P＞0．05），EF组CDK4的表达在72h明显增高（P＜0．05）。结论：烧伤后早期肠道喂养能加速肠粘膜上皮细胞周期的进程以及受损肠粘膜的修复与更新。细胞周期蛋白及CDK在其中起重要作用。     

Immediate early genes and p21 regulation in liver of rats with acute hepatic failure

It has been observed that liver regeneration in acute hepatic failure (AHF) is suppressed [Eguchi et al. Hepatology 1996;24(6):1452-9]. The molecular mechanism regulating this inhibition is not known. We previously reported that in AHF rats, hepatocyte proliferation was significantly impaired with elevation in serum IL-6, TGF-beta1, and HGF [Kamohara et al. Biochem Biophys Res Commun 2000;273(1):129-35]. Following either 70% partial hepatectomy (PH) or liver injury, quiescent mature hepatocytes are "primed" to re-enter the cell cycle. The process of "priming" appears to be triggered by extracellular cytokines (IL-6 and TNF-alpha) and is characterized by expression of immediate early genes. Under the stimulation of growth factors such as HGF, "primed" hepatocytes exit the G1 phase of the cell cycle. G1-associated cyclins and their inhibitors play a pivotal role in G1/S cell cycle transition. Here, we demonstrate that immediate early gene (i.e. c-myc, c-fos) expression and AP-1 activity are preserved in AHF rat livers despite absence of hepatocyte proliferation. In contrast, p21 mRNA and protein are both over-expressed in AHF livers compared to livers from rats undergoing PH; this elevation leads to inhibition in Cdk2 activity, resulting in G1 cell cycle arrest and inhibition of regeneration.