OBJECTIVETo explore the possible mechanism(s) of taurine-inhibiting the proliferation of hepatic stellate cells (HSC), this study investigated the effect of taurine on the HSC cell cycle and its regulatory protein expression.

METHODSCell proliferation was assessed by MTT assay. Cell cycle was analyzed by flow cytometry. Cell cycle regulatory protein Cyclin D1 and P21waf1 expression were determined by immunocytochemistry and image-analysis system, and real-time quantitative PCR.

RESULTSHSC proliferation was markedly inhibited when HSC were treated with taurine at concentrations of 5, 10, 20, 30, 40 and 50 mmol/L for 48 hours, and the inhibition rates were 6.7%, 14.4%, 23.3%, 32.2%, 36.7% and 45.6% respectively (P < 0.05-0.01). In the flow cytometry analysis, it was found that taurine could block HSC in the G0/G1 phase from entering the S phase, resulting in more cells in the G0/G1 phase and fewer in the S phase. The percentage of the cells in the G0/G1 phase and the S phase at the dosage of 40 mmol/L were 68.2%+/-1.4% and 26.2+/-1.3% respectively, which was significantly different in comparison to the controls (56.2%+/-1.7% and 38.5%+/-0.8% respectively, P < 0.01). HSC expressed cyclin D1 and P21waf1. Taurine inhibited cyclin D1 expression and induced P21waf1 expression. The cyclin D1 protein and mRNA in the HSC treated with 40 mmol/L taurine were significantly reduced compared with the controls [protein (optical density value): 0.13+/-0.02 versus 0.18+/-0.02, P < 0.01; mRNA: 5776.7+/-3345.0 versus 18,400.6+/-1374.8 copies/10(6) GAPDH, P < 0.01]; and the P21waf1 protein and mRNA were markedly increased compared with the controls [protein (optical density value): 0.19+/-0.02 versus 0.14+/-0.01, P < 0.01; mRNA: 44,866.7+/-3910.7 versus 16,933.3+/-960.9 copies/10(6) GAPDH, P less than 0.05].

CONCLUSIONSCyclin D1 and P21waf1 were cell cycle regulatory proteins in HSC, and taurine can inhibit the HSC cyclin D1 expression and stimulate P21waf1 expression, facilitate arresting cells in G0/G1 phase, and suppress cell proliferation.

Animals ; Cell Cycle Proteins ; biosynthesis ; genetics ; Cell Line ; Cell Proliferation ; Cyclin D1 ; biosynthesis ; genetics ; Cyclin-Dependent Kinase Inhibitor p21 ; biosynthesis ; genetics ; Depression, Chemical ; Hepatocytes ; cytology ; Rats ; Taurine ; pharmacology

To examine the effects of ischemia and anoxia on cell activation and cell cycle of astrocytes in vitro, the cell cycles and the proliferation of astrocytes in different time points after ischemia and anoxia were studied by flow cytometry and BrdU labeling and the expression of GFAP and cyclin D1 was detected by the fluorescence immunochemistry. After ischemia and anoxia in vitro, the astrocytes in S phase were significantly increased as compared with those in the normal group and the proliferating ability of the astrocytes was highest 6 h after the treatment as revealed by BrdU pulse labeling, but the astrocytes in S phase and proliferating ability were decreased after 6 h. At the early stages of ischemia and anoxia, the positive staining intensity of GFAP was increased, peaked at 6th h, while 12 h after the ischemia and anoxia, the positive staining intensity of GFAP became weak, and the expression of cyclin D1 was gradually increased after the ischemic and anoxic damage. It is concluded that astrocytes are activated to proliferate and enter new cycle events by ischemia and anoxia, and cyclin D1 is implicated in the proliferation and repair of astrocytes. The cell cycle events are closely associated with the proliferation and activation of astrocytes.
Animals, Newborn ; Astrocytes/*cytology ; Cell Cycle ; Cell Hypoxia ; Cell Proliferation ; Cells, Cultured ; Cyclin D1/biosynthesis ; Cyclin D1/genetics ; Glial Fibrillary Acidic Protein/*biosynthesis ; Glial Fibrillary Acidic Protein/genetics ; Rats, Wistar

OBJECTIVETo study the role of cyclin D1 in malignant transformation of human embryonic lung diploid fibroblasts (HELF) induced by quartz.

METHODSpXJ41-cyclin D1 expressing sense and antisense cyclin D1 RNA were transinfected into malignant transformed HELF induced by quartz with DNA recombination and gene transduction. The expression of cyclin D1 was detected with hybridization in situ and immunohistochemistry methods to analyze changes in cell growth, double multiplication time, distribution of cell cycles, colony forming ability on soft agar, etc., before and after cyclin D1 transduction.

RESULTSDuring the process of malignant transformation of HELF induced by quartz, cyclin D1 gene was overexpressed. Antisense pXJ41-cyclin D1 RNA could suppress the growth and proliferation of malignant transformed cells induced by quartz. Growth speed of antisense pXJ41-cyclin D1 transinfected cells decreased by 58.69% on the 8th day in culture, as compared to malignant transformed cells induced by quartz, and its double multiplication time prolonged from 21.0 h to 31.4 h. Antisense cyclin D1 RNA led to cell cycle arrest, resulting in lengthened G1 phase (proportion of cells in phase G1 increased to 52.7% from 45.1% and that of cells in phase S decreased to 33.1% from 40.3%). Colony forming rate reduced significantly and size of colony became smaller.

CONCLUSIONSAbnormal expression of cyclin D1 in cells related to their malignant transformation induced by quartz. Highly expressed cyclin D1 could play an important role in maintaining the transformed phenotype of malignant cells.

Cell Transformation, Neoplastic ; Cells, Cultured ; Cyclin D1 ; biosynthesis ; genetics ; Embryo, Mammalian ; Fibroblasts ; cytology ; Humans ; Lung ; cytology ; Quartz ; toxicity

OBJECTIVETo examine the expressions of E-cadherin, beta-catenin and cyclin D1 in the skin lesions of patients with psoriasis vulgaris, and understand their possible roles in keratinocyte hyperproliferation in these patients.

METHODSImmunohistochemistry was performed to detect the expressions of E-cadherin, beta-catenin and cyclin D1 in the normal skin tissues and psoriatic lesions.

RESULTSIn normal skin tissues, positive staining for E-cadherin and beta-catenin was detected in all layers of the normal epidermis at the sites of cell-cell junctions, and downregulation of E-cadherin and beta-catenin expression was found in the granular layer and basal layer of the psoriatic lesions. Cyclin D1 overexpression was observed mainly in the basal layer of the lesions, which was correlated to abnormal expression of beta-catenin.

CONCLUSIONDownregulation of E-cadherin and beta-catenin expression and cyclin D1 overexpression in psoriatic skin are probably involved in keratinocyte hyperproliferation in psoriasis vulgaris.

Adult ; Cadherins ; biosynthesis ; Cyclin D1 ; biosynthesis ; Down-Regulation ; Epidermis ; metabolism ; pathology ; Female ; Humans ; Immunohistochemistry ; Male ; Psoriasis ; metabolism ; pathology ; beta Catenin ; biosynthesis

Carcinoma, Hepatocellular ; metabolism ; pathology ; Cyclin D1 ; biosynthesis ; Hepatitis B virus ; Humans ; Liver ; pathology ; Liver Cirrhosis ; metabolism ; pathology ; NF-kappa B ; biosynthesis ; Trans-Activators ; biosynthesis

OBJECTIVETo explore the effect of transforming growth factor alpha (TGFalpha) on the expression of cyclin E and D1 in gastric carcinoma cells.

METHODSHuman gastric adenocarcinoma SGC7901 cells were cultured routinely and synchronized at G(0)/G(1) phase in serum-free RPMI-1640. The percentage of the cells at G(0)/G(1) phase was detected by propidium iodide staining and flow cytometry (FCM), and the synchronized cells were cultured in RPMI-1640 supplemented with 2.5% calf serum and treated with 10, 30, and 50 microg/L TGFalpha for 5 h. The expression of cyclin E and D1 in SGC7901 cells was detected by immunofluorescent staining and FCM.

RESULTSThe percentage of the cells at G(0)/G(1) phase increased from 54% in routine culture to 72% in the serum-free RPMI-1640 culture. TGFalpha treatment of the cells synchronized at G(0)/G(1) phase induced significant increment of cyclin E and D1 expressions (P<0.001), and at the dose of TGFalpha of 50 microg/L, their expressions increased by 25.18% and 27.52%, respectively (P<0.001).

CONCLUSIONTGFalpha can increase the expression of cyclin E and D1 in gastric carcinoma cells to promote their cell cycle progress.

Adenocarcinoma ; metabolism ; pathology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cyclin D1 ; biosynthesis ; Cyclin E ; biosynthesis ; Flow Cytometry ; Fluorescent Antibody Technique ; Humans ; Stomach Neoplasms ; metabolism ; pathology ; Transforming Growth Factor alpha ; pharmacology

The effects of retinoic acid on the beta-catenin/TCF pathway in cultured porcine tracheobronchial epithelial cells (TBEC) were investigated. After TBEC were treated with retinoic acid at various concentrations, mRNA and protein changes of beta-catenin in cytoplasm, nucleus and whole cell of the TBEC were observed by immunocytochemical stain, RT-PCR and Western blotting. And the changes of the target gene cyclinD1 of beta-catenin/TCF pathway were also observed. It was found that there was no significant difference in beta-cat mRNA level after retinoic acid treatment. However, the expression of beta-catenin in the whole cell and cytoplasm was elevated with the increase of retinoic acid concentration (P<0. 01). The nuclear protein beta-catenin and target gene cyclinD1 of beta-catenin/TCF pathway was decreased (P<0.05). It was indicated that retinoic acid could increase beta-catenin level of the whole cell protein and decrease nuclear beta-catenin, downregulating beta-cat/TCF signaling activity and reducing target gene cyclinD1 protein level. As a result, retinoic acid can downregulate beta-catenin/TCF pathway in porcine tracheobronchial epithelial cell, suggesting that retinoic acid can inhibit the proliferation and accelerate differentiation of tracheobronchial epithelial cells.
Animals ; Bronchi ; cytology ; metabolism ; Cells, Cultured ; Cyclin D1 ; biosynthesis ; genetics ; Epithelial Cells ; cytology ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; Swine ; TCF Transcription Factors ; biosynthesis ; genetics ; Trachea ; cytology ; metabolism ; Tretinoin ; pharmacology ; beta Catenin ; biosynthesis ; genetics

OBJECTIVETo investigate the effect of ionizing radiation on the expression of p16, CyclinD1, and CDK4 in mouse thymocytes and splenocytes.

METHODSFluorescent staining and flow cytometry analysis were employed for the measurement of protein expression.

RESULTSIn time course experiments, it was found that the expression of p16 protein was significantly increased at 8, 24, and 48 h for thymocytes (P < 0.05, P < 0.01, and P < 0.05, respectively) and at 24 h for splenocytes (P < 0.05) after whole body irradiation (WBI) with 2.0 Gy X-rays. However, the expression of CDK4 protein was significantly decreased from 8 h to 24 h for thymocytes (P < 0.05-P < 0.01) and from 8 h to 72 h for splenocytes (P < 0.05-P < 0.01). In dose effect experiments, it was found that the expression of p16 protein in thymocytes and splenocytes was significantly increased at 24 h after WBI with 1.0, 2.0, and 4.0 Gy (P < 0.05-P < 0.01), whereas the expression of CDK4 protein was significantly decreased with 2.0 Gy for thymocytes (P < 0.05) and 0.5-6.0 Gy for splenocytes (P < 0.05-P < 0.01). Results also showed that the expression of CyclinD1 protein decreased markedly in both thymocytes and splenocytes after exposure.

CONCLUSIONThe results indicate that the expression of p16 protein in thymocytes and splenocytes can be induced by ionizing radiation, and the p16-CyclinD1/CDK4 pathway may play an important role for G1 arrest of thymocytes induced by X-rays.

Animals ; Cyclin D1 ; biosynthesis ; Cyclin-Dependent Kinase 4 ; Cyclin-Dependent Kinase Inhibitor p16 ; biosynthesis ; Cyclin-Dependent Kinases ; biosynthesis ; Dose-Response Relationship, Radiation ; Flow Cytometry ; Male ; Mice ; Mice, Inbred Strains ; Proto-Oncogene Proteins ; Radiation Dosage ; Spleen ; cytology ; metabolism ; radiation effects ; Thymus Gland ; cytology ; metabolism ; radiation effects ; X-Rays

Carcinoma, Hepatocellular ; microbiology ; pathology ; Cell Line, Tumor ; Cyclin D1 ; biosynthesis ; genetics ; Helicobacter pylori ; physiology ; Humans ; Liver Neoplasms ; microbiology ; pathology ; Proliferating Cell Nuclear Antigen ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics

OBJECTIVETo construct the eukaryotic expression vectors of human cyclin D1 gene and express them in poorly differentiated nasopharyngeal carcinoma cells (CNE-2Z cells).

METHODSThe full-length cyclin D1 was cloned from CNE-2Z cells by RT-PCR. The cDNA fragments were inserted into pIRES2-EGFP plasmids and pEGFP-C2 plasmids and confirmed by restriction enzyme digestion, PCR and sequencing. The recombinant vectors were transfected into CNE-2Z cells via Lipofectamine 2000, and the expression of cyclin D1 in the cells was examined by immunofluorescence and Western blotting.

RESULTSAgarose gel electrophoresis showed a 918 bp band of the RT-PCR products, which matched the expected size. Restriction enzyme digestion, PCR and sequencing demonstrated successful construction of the recombinant vectors. CNE-2Z cells transfected with the recombinant vectors expressed cyclin D1 protein or cyclin D1-GFP protein as were verified by immunofluorescence and Western blotting.

CONCLUSIONWe have cloned cyclin D1 gene and constructed its eukaryotic expression vectors that can be expressed in nasopharyngeal carcinoma cells, which may facilitate the study of the role of cyclin D1 in the development of nasopharyngeal carcinoma.

Cell Line, Tumor ; Cloning, Molecular ; Cyclin D1 ; biosynthesis ; genetics ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; biosynthesis ; genetics ; Humans ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Plasmids ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Transfection