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Cell Cycle Regulatory Proteins (cell + cycle_regulatory_protein)
Selected Abstractsp16Ink4a is Overexpressed in H. pylori -Associated Gastritis and is Correlated with Increased Epithelial ApoptosisHELICOBACTER, Issue 1 2003Haim Shirin ABSTRACT Background. Cell cycle regulatory proteins may be critical targets during carcinogenesis. We have previously shown that chronic H. pylori infection is associated with decreased expression of the cyclin dependent kinase inhibitor (CDI) p27kip1. Loss of p27kip1 and p16Ink4a (p16) expression, another CDI, has been reported during the progression of gastric tubular adenomas to advanced gastric cancer. The aim of the current study was to examine whether H. pylori infection also affects the expression of p16 in the gastric mucosa of H. pylori- infected patients. Methods. p16 expression was evaluated in gastric antral biopsies by immunohistochemistry in 50 patients with nonulcer dyspepsia (n = 18 uninfected, n = 32 H. pylori infected, 24 by cagA+ strains). Adjacent sections were stained for proliferating epithelial cells (by Ki67) and for apoptotic cells (by TUNEL assay). Results. Both in H. pylori infected and uninfected patients the expression of p16 was higher in the neck and base of the gland than in the foveolar region. Epithelial staining for p16 was increased with H. pylori infection (31.3% vs. 11.1% in the foveolar region, 68.8% vs. 27.8% in the neck and 75% vs. 50% in the glandular base). There was no correlation between the expression of 16 and proliferation but there was a significant positive correlation between apoptosis and 16 immunostaining. Conclusions. The tumor suppressor gene 16 is over expressed in gastric epithelial cells of H. pylori infected patients and this is associated with an increase in apoptosis. These findings suggest a possible role for this cell cycle regulator in the increase in gastric cell turnover that is associated with H. pylori infection. [source] S179D prolactin sensitizes human prostate cancer cells such that physiological concentrations of 1, 25 dihydroxy vitamin D3 result in growth inhibition and cell deathTHE PROSTATE, Issue 14 2007Wei Wu Abstract BACKGROUND S179D Prolactin (PRL) is a molecular mimic of naturally phosphorylated human PRL which has been shown to inhibit the growth of human prostate cancer cells both in vitro and when grown as tumors in nude mice. METHODS In the current study, we have investigated the potential interplay between S179D PRL and 1,25 dihydroxy vitamin D3 (1,25D) in the inhibition of prostate cancer cell growth by incubating cells under circumstances where each hormone alone has no effect. RESULTS Incubation of DU145 or PC3 cells in 100 pM 1,25D or 10 nM S179D PRL for 3 days showed no effect of each alone on expression of the vitamin D receptor (VDR), or the cell cycle regulatory protein p21, or on cell number. Incubation in both together increased expression of the VDR and p21 two to threefold. This co-operative effect was reproduced when activation of the p21 promoter was analyzed using a p21-luciferase (p21-luc) construct. Elimination of the VDR response element from p21-luc eliminated response to the hormone combination, showing that the effect on p21 was through the VDR. Most importantly, S179D PRL sensitized the cells to 1,25D such that there was a concentration-related reduction in cell number versus controls between 40 and 160 pM. At least part of this effect was via the induction of cell death. CONCLUSIONS These results suggest that combined anti-tumor therapy may be very efficacious and that the dose of 1,25D required may be below the range that results in hypercalcemia. Prostate 67: 1498,1506, 2007. © 2007 Wiley-Liss, Inc. [source] Attenuation of Bleomycin-Induced Lung Fibrosis by Oxymatrine Is Associated with Regulation of Fibroblast Proliferation and Collagen Production in Primary CultureBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2008Xiaohong Chen Oxymatrine is an alkaloid extracted from the Chinese herb Sophora japonica (Sophora flavescens Ait.) with capacities of anti-inflammation, inhibition of immune reaction, antivirus, protection against acute lung injury and antihepatic fibrosis. In this study, the effect of oxymatrine on pulmonary fibrosis was investigated using a bleomycin-induced pulmonary fibrosis mouse model. The results showed that bleomycin challenge provoked severe pulmonary fibrosis with marked increase in hydroxyproline content of lung tissue and lung fibrosis fraction, which was prevented by oxymatrine in a dose-dependent manner. In addition, bleomycin injection resulted in a marked increase of myeloperoxidase activity and malondialdehyde level that was attenuated by oxymatrine. Administration of oxymatrine inhibited the proliferation of murine lung fibroblasts, arrested the cells at G0/G1 phase and reduced the expression of cell cycle regulatory protein, cyclin D1 in vitro. Furthermore, the steady-state production of collagen and the expression of ,1(I) pro-collagen and ,2(I) pro-collagen mRNA in fibroblasts were inhibited by oxymatrine in a dose-dependent manner. These results suggested that oxymatrine may attenuate pulmonary fibrosis induced by bleomycin in mice, partly through inhibition of inflammatory response and lipid peroxidation in lung induced by bleomycin and reduction of fibroblast proliferation and collagen synthesis. [source] Level of reactive oxygen species induced by p21WAF(1)/CIP(1) is critical for the determination of cell fateCANCER SCIENCE, Issue 7 2009Takafumi Inoue p21WAF(1)/CIP(1) is a well-known cell cycle regulatory protein which is overexpressed in several cancer cell lines, and known to determine cell fate. We generated three recombinant adenovirus vectors that expressed either the full-length p21 (Ad-p21F), a p21 mutant with a deletion of the C-terminal proliferative cell nuclear antigen (PCNA) binding domain (Ad-p21N), or a p21 mutant with a deletion of the N-terminal cyclin-dependent kinase binding domain (Ad-p21C). We transfected these vectors into five cancer cell lines. Premature senescence was induced in all of the lines only following transfection with Ad-p21N and Ad-p21F. In addition, apoptosis was also induced in LoVo and HCT116 cells that harbored wild-type p53 and the reactive oxygen species (ROS) level was higher than in senescent cells. Finally, the induction of apoptosis was inhibited by using siRNA to downregulate p53. This observation implies that there is a feedback signaling loop involving p21/ROS/p53 in apoptotic responses. It appears to be, at least in part, driven by high levels of p21 protein. Next, we investigated the cell death effect of endogenous p21 protein on cell fate using sodium butyrate (NaB). Treatment with 1 mM NaB or 2 to 5 mM NaB induced senescence or apoptosis, respectively. The level of intracellular ROS in 5 mM NaB treated cells was 2-fold higher, compared with that in 1 mM NaB treated cells. We also demonstrated that DNA damage response signals including ataxia telangiectasia mutated, ,H2AX, and p38 MAPK were involved in NaB-induced cell death. The magnitude of intracellular ROS levels in response to p21 elicited either senescence or apoptosis in the cancer cell lines. (Cancer Sci 2009; 100: 1275,1283) [source] Isothiocyanate E-4IB induces MAPK activation, delayed cell cycle transition and apoptosisCELL PROLIFERATION, Issue 3 2007J. Bodo Methods and results: In the current investigation, we examined the consequence of activating of signalling pathways during the release the cells from the block at G1/S boundary by synthetic isothiocyanate E-4IB. Using synchronized leukaemic HL60 cells, we show that activation of mitogen-activated protein kinases ERK1/2, c-Jun N-terminal kinase and p38 signalling pathways by E-4IB are coupled with delayed transition through the cell cycle and rapid cell cycle arrest resulted in diminished mitochondrial membrane potential culminating in apoptosis. These events were accompanied by histone deacetylase inhibition, increase of double strand DNA breaks detected by histone H2AX phosphorylation and up-regulation of cell cycle regulatory protein p21 and phosphorylation of CDC25C phosphatase. Conclusion: These findings suggest that the activation of mitogen-activated protein kinases signalling pathways, followed by the induction cell cycle arrest and apoptosis, might be responsible for anticancer activities of E-4IB. [source] Resveratrol inhibits proliferation of human epidermoid carcinoma A431 cells by modulating MEK1 and AP-1 signalling pathwaysEXPERIMENTAL DERMATOLOGY, Issue 7 2006Arianna L. Kim Abstract:, Resveratrol (trans -3,4,,5-trihydroxystilbene) is a naturally occurring polyphenolic phytoalexin found in grapes, and has been shown to inhibit the growth of various types of cancer cells. We investigated the mechanism of the antiproliferative effect of resveratrol in A431-transformed keratinocytes harbouring mutant p53, and show that it is accompanied by G1 cell cycle arrest, which coincides with a marked inhibition of G1 cell cycle regulatory proteins, including cyclins A and D1 and cyclin-dependent kinase (CDK)6 and p53-independent induction of p21WAF1. Cell cycle arrest was also associated with the accumulation of hypophosphorylated Rb and p27KIP1. Resveratrol inhibited mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)1 > extracellular signal-regulated protein kinase (ERK)1/2 signalling, downregulated c-Jun, and suppressed activating protein (AP)-1 DNA-binding and promoter activity. In addition, the inhibition of MEK1 > ERK1/2 signalling appears to be independent of retinoblastoma protein (pRb) hypophosphorylation in A431 cells, as PD098059 did not suppress pRb phosphorylation. Our results demonstrate that resveratrol affects multiple cellular targets in A431 cells, and that the downregulation of both AP-1 and pRb contributes to its antiproliferative activity in these cells. [source] High glucose increase cell cycle regulatory proteins level of mouse embryonic stem cells via PI3-K/Akt and MAPKs signal pathwaysJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2006Yun Hee Kim This study examined the effects of high glucose on cell proliferation and its related signal pathways using mouse embryonic stem (ES) cells. Here, we showed that high glucose level significantly increased [3H]thymidine incorporation, BrdU incorporation, the number of cells, [3H]leucine, and [3H]proline incorporation in a time-(>3 hr) and dose-(>25 mM) dependent manner. Moreover, high glucose level increased the cellular reactive oxygen species (ROS), Akt, and mitogen-activated protein kinases (MAPKs) phosphorylation. Subsequently, these signaling molecules involved in high glucose-induced increase of [3H]thymidine incorporation. High glucose level also increased cyclin D1, cyclin E, cyclin-dependent kinase (CDK) 2, and CDK 4 protein levels, which is cell cycle regulatory proteins acting in G1,S phase of cell cycle. Inhibition of phosphatidylinositol 3-kinase (PI3-K) (LY 294002: PI3-kinase inhibitor, 10,6 M), Akt (Akt inhibitor, 10,5 M), and p44/42 MAPKs (PD 98059: MEK inhibitor, 10,5 M) decreased these proteins. High glucose level phosphorylated the RB protein, which was decreased by inhibition of PI3-K and Akt. In conclusion, high glucose level stimulates mouse ES cell proliferation via the PI3-K/Akt and MAPKs pathways. J. Cell. Physiol. 209: 94,102, 2006. © 2006 Wiley-Liss, Inc. [source] Differential expression of periodontal ligament-specific markers and osteogenic differentiation in human papilloma virus 16-immortalized human gingival fibroblasts and periodontal ligament cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2007S.-H. Pi Background and Objective:, Periodontal ligament cells and gingival fibroblasts are important in the remodeling of periodontal tissue, but human papilloma virus (HPV)16-immortalized cell lines derived from human periodontal ligament cells and gingival fibroblasts has not been characterized. The purpose of this study was to establish and differentially characterize the immortalized cell lines from gingival fibroblasts and periodontal ligament by HPV16 transfection. Material and Methods:, Cell growth, cell cycle analysis, western blot for cell cycle regulatory proteins and osteogenic differentiation markers, and reverse transcription,polymerase chain reaction for periodontal ligament-specific markers were performed. Results:, Both immortalized cell lines (immortalized gingival fibroblasts and immortalized periodontal ligament cells) grew faster than primary cultured gingival fibroblasts or periodontal ligament cells. Immortalized gingival fibroblasts and immortalized periodontal ligament cells overexpressed proteins p16 and p21, and exhibited degradation of proteins pRb and p53, which normally cause cell cycle arrest in G2/M-phase. Western blotting and reverse transcription,polymerase chain reaction for periodontal ligament-specific and osteogenic differentiation marker studies demonstrated that a cell line, designated IPDL, mimicked periodontal ligament gene expression for alkaline phosphatase, osteonectin, osteopontin, bone sialoprotein, bone morphogenic protein-2, periostin, S-100A4 and PDLs17. Conclusion:, These results indicate that IPDL and immortalized gingival fibroblast cell lines consistently retain normal periodontal ligament and gingival fibroblast phenotypes, respectively, and periodontal ligament markers and osteogenic differentiation in IPDL are distinct from immortalized gingival fibroblast cells. [source] Cooperative inhibitory effect of ZD1839 (Iressa) in combination with 17-AAG on glioma cell growth,MOLECULAR CARCINOGENESIS, Issue 5 2006Daniel R. Premkumar Abstract ZD1839 ("Iressa") is an orally active, selective epidermal growth factor (EGF) receptor-tyrosine kinase inhibitor. We evaluated the antitumor activity of ZD1839 in combination with HSP90 antagonist, 17-AAG in malignant human glioma cell lines. ZD1839 independently produced a dose-dependent inhibition of cellular proliferation in glioma cells grown in culture with time- and dose-dependent accumulation of cells in G1 phase of the cell cycle on flow cytometric analysis, although the concentrations required for optimal efficacy were at or above the limits of clinically achievable levels. Because the heat shock protein (HSP) is involved in the conformational maturation of a number of signaling proteins critical to the proliferation of malignant glioma cells, we hypothesized that the HSP90 inhibitor 17-AAG would potentiate ZD 1839-mediated glioma cytotoxicity by decreasing the activation status of EGF receptor, as well as downregulating the levels of other relevant signaling effectors. We, therefore, examined the effects of ZD1839 and 17-AAG, alone and in combination, on signal transduction and apoptosis in a series of malignant glioma cell lines. Simultaneous exposure to these inhibitors significantly induced cell death and quantitative analysis revealed that interaction between ZD1839 and 17-AAG-induced cytotoxicity was synergistic, leading to a pronounced increase in active caspase-3 and PARP cleavage. No significant growth inhibition or caspase activation was seen in control cells. The enhanced cytotoxicity of this combination was associated with diminished Akt activation and a significant downregulation of EGFR receptor, Raf-1 and mitogen activated protein kinase (MAPK). Cells exposed to 17-AAG and ZD1839 displayed a significant reduction in cell cycle regulatory proteins, such as CDK4 and CDK6. Taken together, these findings suggest that ZD1839, an EGF receptor tyrosine kinase inhibitor, plays a critical role in regulating the apoptotic response to 17-AAG and that multi-site targeting of growth signaling and cell survival pathways could provide a potent strategy to treat patients with malignant gliomas. © 2006 Wiley-Liss, Inc. [source] Malignant transformation of mature cystic teratoma to squamous cell carcinoma involves altered expression of p53- and p16/Rb-dependent cell cycle regulator proteinsPATHOLOGY INTERNATIONAL, Issue 12 2008Atsuko Iwasa Ovarian mature cystic teratomas (MCT) uncommonly undergo malignant transformation to squamous cell carcinoma (SCC). While alterations in the p53 tumor suppressor gene and protein have been shown, few studies have analyzed other molecular changes leading to this malignant conversion. The purpose of the present study was to investigate 21 samples of SCC arising in MCT for altered expression in known p53- and p16/Rb-dependent cell cycle regulatory proteins, and the association between their expression and cellular proliferation and histological features. Overexpression of the p53 protein was observed in 14 SCC (67%), while four (19%) had point mutations in the p53 gene. Reduced expression of the p16 protein was observed in 18 SCC (86%), while p16 gene alterations (hypermethylation (29%) and point mutation (33%)) were found in 11 (52%). Furthermore, a statistically significant correlation was observed between p53 and Rb overexpression (P = 0.0010), and the overexpression of both p53 and Rb was respectively significantly correlated with increased cellular proliferation. The results indicate that alterations in both the p53 and p16-Rb pathways are associated with SCC arising in MCT. [source] Rosiglitazone Inhibits Cell Proliferation by Inducing G1 Cell Cycle Arrest and Apoptosis in ADPKD Cyst-Lining Epithelia CellsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2010Yawei Liu Many drugs inhibiting cell proliferation have been proved to be effective in slowing the disease progression in ADPKD. Recent evidence has suggested that peroxisome proliferator-activated receptor , (PPAR,) ligands have anti-neoplasm effects through inhibiting cell growth and inducing cell apoptosis in various cancer cells. In the present study, we examined the expression of PPAR, in human ADPKD kidney tissues and cyst-lining epithelial cell line, and found that the expression of PPAR, was greater in ADPKD kidney tissues and cyst-lining epithelial cell line than in normal kidney tissues and human kidney cortex (HKC) cell line. Rosiglitazone inhibited significantly proliferation of cyst-lining epithelial cells in a concentration- and time-dependent manner. These effects were diminished by GW9662, a specific PPAR, antagonist. Cell cycle analysis showed a G0/G1 arrest in human ADPKD cyst-lining epithelial cells with rosiglitazone treatment. Analysis of cell cycle regulatory proteins revealed that rosiglitazone decreased the protein levels of proliferating cell nuclear antigen, pRb, cyclin D1, cyclin D2 and Cdk4 but increased the levels of p21 and p27 in a dose-dependent manner. Rosiglitazone also induced apoptosis in cyst-lining epithelial cells, which was correlated with increased bax expression and decreased bcl-2 expression. These results suggest PPAR, agonist might serve as a promising drug for the treatment of ADPKD. [source] BRCA1 Expression Status in Relation to DNA Methylation of the BRCA1 Promoter Region in Sporadic Breast CancersCANCER SCIENCE, Issue 5 2000Youko Niwa To understand the biological role of BRCA1 in sporadic breast cancers, the relationship between DNA methylation of the BRCA1 Promoter region and BRCA1 expression was studied using molecular biological and immunohistochemical methods. Furthermore, BRCA1 expression was compared with the expression of various cell cycle regulatory proteins and the morphological nuclear grade of cancer cells. Of 32 sporadic breast cancers investigated in this study, 10 (31%) revealed DNA methylation of the BRCA1 promoter region. The expression of BRCA1 was observed in the nuclei of cancer cells and 18 (56%) of 32 cancers were positive for BRCA1 immunoreactivity. Breast cancers with BRCA1 methylation lacked BRCA1 expression, except for only three cancers, and there was a significant inverse relationship between BRCA1 methylation and its expression in sporadic breast cancers (P=0.043). Compared with the expression of various cell cycle regulatory proteins, breast cancers with BRCA1 methylation showed decreased expression of estrogen receptor (P=0.016) and p27 (P=0.018) and increased expression of p21 (P=0.011). Furthermore, breast cancers without BRCA1 expression or with BRCA1 methylation had a tendency to contain nuclei with higher grade. These findings indicate that BRCA1 methylation might greatly influence its expression and BRCA1 expression might play an important role in cell cycle regulation and influence the grade of malignancy of sporadic breast cancers. [source] Short-period hypoxia increases mouse embryonic stem cell proliferation through cooperation of arachidonic acid and PI3K/Akt signalling pathwaysCELL PROLIFERATION, Issue 2 2008S. H. Lee Hypoxia plays important roles in some early stages of mammalian embryonic development and in various physiological functions. This study examined the effect of arachidonic acid on short-period hypoxia-induced regulation of G1 phase cell-cycle progression and inter-relationships among possible signalling molecules in mouse embryonic stem cells. Hypoxia increased the level of hypoxia-inducible factor-1, (HIF-1,) expression and H2O2 generation in a time-dependent manner. In addition, hypoxia increased the levels of cell-cycle regulatory proteins (cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and CDK4). Maximum increases in the level of these proteins and retinoblastoma phosphorylation were observed after 12,24 h of exposure to hypoxic conditions, and then decreased. Alternatively, the level of the CDK inhibitors, p21Cip1 and p27Kip1 were decreased. These results were consistent with the results of [3H]-thymidine incorporation and cell counting. Hypoxia also increased the level of [3H]-arachidonic acid release and inhibition of cPLA2 reduced hypoxia-induced increase in levels of the cell-cycle regulatory proteins and [3H]-thymidine incorporation. The level of cyclooxygenase-2 (COX-2) was also increased by hypoxia and inhibition of COX-2 decreased the levels of cell-cycle regulatory proteins and [3H]-thymidine incorporation. Indeed, the percentage of cells in S phase, levels of cell cycle regulatory proteins, and [3H]-thymidine incorporation were further increased in hypoxic conditions with arachidonic acid treatment compared to normoxic conditions. Hypoxia-induced Akt and mitogen-activated protein kinase (MAPK) phosphorylation was inhibited by vitamin C (antioxidant, 10,3 M). In addition, hypoxia-induced increase of cell-cycle regulatory protein expression and [3H]-thymidine incorporation were attenuated by LY294002 (PI3K inhibitor, 10,6 M), Akt inhibitor (10,6 M), rapamycin (mTOR inhibitor, 10,9 M), PD98059 (p44/42 inhibitor, 10,5 M), and SB203580 (p38 MAPK inhibitor, 10,6 M). Furthermore, hypoxia-induced increase of [3H]-arachidonic acid release was blocked by PD98059 or SB203580, but not by LY294002 or Akt inhibitor. In conclusion, arachidonic acid up-regulates short time-period hypoxia-induced G1 phase cyclins D1 and E, and CDK 2 and 4, in mouse embryonic stem cells through the cooperation of PI3K/Akt/mTOR, MAPK and cPLA2 -mediated signal pathways. [source] | |||||||||||||