OBJECTIVETo investigate the expressions of cyclin E, cyclin dependent kinase 2 (CDK-2) and cyclin-dependent kinase inhibitor p57(KIP2) in human gastric cancer, and to evaluate the relationships between protein levels and clinicopathological parameters.

METHODSWestern blot was used to measure the expressions of cyclin E, CDK-2 and p57(KIP2) proteins in the surgically resected gastric carcinoma, adjacent normal mucosa and metastatic lymph nodes from 36 patients.

RESULTSCyclin E and CDK-2 protein levels were higher in gastric cancer tissues in comparison with normal tissues (P < 0.05). Overexpression of cyclin E was correlated with lymph node involvement, poor histological grade and serosa invasion (P < 0.05). Overexpression of CDK-2 was correlated with lymph nodes involvement (P < 0.05). No statistically significant difference between cyclin E and CDK-2 expression was found when samples were stratified according to tumor size (P > 0.05). Expression of cyclin E and CDK-2 showed a positive linear correlation (r = 0.451, P = 0.01). Protein levels of p57(KIP2) were lower in gastric cancer tissues than in the normal mucosa (P < 0.05). Decreased expression of p57(KIP2) was correlated with lymph node involvement (P < 0.05). No statistically significant difference in p57(KIP2) expression was found when sample were stratified according to tumor size, histological grade or serosa invasion (P > 0.05). In metastatic lymph nodes, expression of cyclin E was increased and the expression of p57(KIP2) decreased.

CONCLUSIONOverexpressions of cyclin E, CDK-2 and downregulated expression of p57(KIP2) may play important roles in tumorigenesis and metastatic potential of gastric cancer.

Blotting, Western ; CDC2-CDC28 Kinases ; Cyclin E ; analysis ; physiology ; Cyclin-Dependent Kinase 2 ; Cyclin-Dependent Kinase Inhibitor p57 ; Cyclin-Dependent Kinases ; analysis ; physiology ; Humans ; Lymphatic Metastasis ; Nuclear Proteins ; analysis ; physiology ; Protein-Serine-Threonine Kinases ; analysis ; physiology ; Stomach Neoplasms ; chemistry ; pathology

PURPOSE: p27Kip1 protein is an inhibitor of cyclin-dependent kinases and is thought to be a potential prognostic indicator for numerous human cancers. We investigated the expression of p27Kip1 in gastric cancer in order to estimate its clinical utility. METHODS: Immunohistochemical assay for p27Kip1 protein was performed in 64 patients with primary gastric cancer. The correlation between p27Kip1 and clinical-biological parameters including patient survival was analyzed. RESULTS: p27Kip1 expression was suppressed in 40 (62.5%) of 64 gastric cancer patients. Expression of p27Kip1 was significantly reduced in poorly differentiated cancers (82.1%, 23/28; P=0.015) and was also reduced in tumors with a high S-phase fraction as compared with tumors showing a low S-phase fraction (86.7%, 26/30, 41.2%, 14/34; P=0.0002). In univariate analysis, the extent of the disease (P<0.001), and reduced expression of p27Kip1 (P=0.0006) were statistically significant to predict the patient's outcome, however depth of invasion (P=0.008) and pathologic stage (P=0.009) emerged as significant prognostic indicators in the multivariate analysis. CONCLUSION: The expression of p27Kip1 is closely linked with cell proliferation and differentiation of human gastric cancer. p27Kip1 appears to have potential as a prognostic marker in the management of gastric cancer patients.
Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor p27* ; Cyclin-Dependent Kinases ; Humans* ; Immunohistochemistry ; Multivariate Analysis ; Prognosis ; Stomach Neoplasms*

OBJECTIVES: The molecular mechanisms that regulate cardiomyocyte cell cycle and terminal differentiation in humans remain largely unknown. To determine which cyclins, cyclin dependent kinases (CDKs) and cyclin kinase inhibitors (CKIs) are important for cardiomyocyte proliferation, we have examined protein levels of cyclins, CDKs and CKIs during normal atrial development in humans. METHODS: Atrial tissues were obtained in the fetus from inevitable abortion and in the adult during surgery. Cyclin and CDK proteins were determined by Western blot analysis. CDK activities were determined by phosphorylation amount using specific substrate. RESULTS: Most cyclins and CDKs were high during the fetal period and their levels decreased at different rates during the adult period. While the protein levels of cyclin D1, cyclin D3, CDK4, CDK6 and CDK2 were still detectable in adult atria, the protein levels of cyclin E, cyclin A, cyclin B, cdc2 and PCNA were not detectable. Interestingly, p27KIP1 protein increased markedly in the adult period, while p21CIP1 protein in atria was detectable only in the fetal period. While the activities of CDK6, CDK2 and cdc2 decreased markedly, the activity of CDK4 did not change from the fetal period to the adult period. CONCLUSION: These findings indicate that marked reduction of protein levels and activities of cyclins and CDKs, and marked induction of p27KIP1 in atria, are associated with the withdrawal of cardiac cell cycle in adult humans.
Adult ; Age Factors ; Animal ; Blotting, Western ; Cell Cycle ; Cells, Cultured ; Comparative Study ; Cyclin A/analysis ; Cyclin B/analysis ; Cyclin D1/analysis ; Cyclin E/analysis ; Cyclin-Dependent Kinases/analysis* ; Cyclins/analysis* ; Female ; Fetal Development ; Heart Atrium/growth & development* ; Heart Atrium/embryology ; Heart Atrium/cytology* ; Heart Atrium/chemistry ; Human ; Male ; Middle Age ; Myocardium/chemistry* ; Rats ; Rats, Sprague-Dawley ; Substances: Cyclin D1 ; Substances: Cyclins ; Substances: Cyclin-Dependent Kinases ; Substances: Cyclin E ; Substances: Cyclin B ; Substances: Cyclin A

The ability of viral oncoproteins to subvert cell cycle checkpoints may constitute a mechanism by which viral oncoproteins induce genetic instability. HPV 16 E6 and E7 disrupt cell cycle checkpoints, particularly affecting nearly all cyclin-dependent kinase inhibitors linked to the G1- and G2- checkpoints, in each case by means of a different mechanism. HPV 16 E7 shows homology with the pRb binding sites of cyclin D1, which consequently releases E2F. In addition, E7 directly binds to p21, and releases PCNA and other S-phase promoting genes. In turn, released E2F activates cyclin E, and cyclin E accelerates p27 proteolysis as a function of the antagonistic reaction of its own inhibitor. The induction of p16 expression is assumed to be indirectly associated with E7, which is upregulated only after prolonged inactivation of Rb. HPV 16 E6 decreased the fidelity of multiple checkpoints controlling both entry into and exit from mitosis, with the mechanism of p53 inactivation. In addition, HPV 16 E6 increased the sensitivity to chemically induced S-phase premature mitosis and decreased mitotic spindle assembly checkpoint function. Alongside the impressive advances made in the understanding of the molecular mechanisms, which HPV disrupts, the validity of these conclusions should be evaluated in the diagnostic and prognostic fields.
Cervix Neoplasms/*pathology/virology ; Cyclin-Dependent Kinases/*antagonists & inhibitors ; Cyclins/analysis ; Female ; *G1 Phase ; *G2 Phase ; Human ; Microfilament Proteins/analysis ; Papillomavirus Infections/*pathology ; *Papillomavirus, Human ; Proliferating Cell Nuclear Antigen/analysis ; Protein p16/analysis ; Tumor Virus Infections/*pathology

BACKGROUNDPulmonary artery smooth muscle cell (PASMC) proliferation plays an important role in pulmonary vessel structural remodelling. At present, the mechanisms related to proliferation of PASMCs are not clear. Focal adhesion kinase (FAK) is a widely expressed nonreceptor protein tyrosine kinase. Recent research indicates that FAK is implicated in signalling pathways which regulate cytoskeletal organization, adhesion, migration, survival and proliferation of cells. Furthermore, there are no reports about the role of FAK in human pulmonary artery smooth muscle cells (HPASMCs). We investigated whether FAK takes part in the intracellular signalling pathway involved in HPASMCs proliferation and apoptosis, by using antisense oligodeoxynucleotides (ODNs) to selectively suppress the expression of FAK protein.

METHODSCultured HPASMCs stimulated by fibronectin (40 microg/ml) were passively transfected with ODNs, sense FAK, mismatch sense and antisense-FAK respectively. Expression of FAK, Jun NH2-terminal kinase (JNK), cyclin-dependent kinase 2 (CDK 2) and caspase-3 proteins were detected by immunoprecipitation and Western blots. Cell cycle and cell apoptosis were analysed by flow cytometry. In addition, cytoplasmic FAK expression was detected by immunocytochemical staining.

RESULTSWhen compared with mismatch sense group, the protein expressions of FAK, JNK and CDK 2 in HPASMCs decreased in antisense-FAK ODNs group and increased in sense-FAK ODNs group significantly. Caspase-3 expression upregulated in HPASMCs when treated with antisense ODNs and downregulated when treated with sense ODNs. When compared with mismatch sense ODNs group, the proportion of cells at G1 phase decreased significantly in sense ODNs group, while the proportion of cells at S phase increased significantly. In contrast, compared with mismatch sense ODNs group, the proportion of cells at G1 phase was increased significantly in antisense-FAK ODNs group. The level of cell apoptosis in antisense-FAK group was higher than in the mismatch sense group and the latter was higher than sense-FAK group. In addition, the sense-FAK ODNs group was strongly stained by immunocytochemistry, whereas the antisense-FAK ODNs group was weakly stained.

CONCLUSIONSThe results suggest that FAK relates to the proliferation of HPASMCs. Antisense-FAK ODNs inhibit HPASMCs proliferation and facilitate their apoptosis. It is possible that FAK via JNK, CDK 2 signalling pathways enhances HPASMCs proliferation and via caspase-3 inhibits HPASMCs apoptosis.

Apoptosis ; CDC2-CDC28 Kinases ; analysis ; Caspase 3 ; Caspases ; analysis ; Cell Cycle ; Cell Proliferation ; drug effects ; Cells, Cultured ; Cyclin-Dependent Kinase 2 ; Focal Adhesion Kinase 1 ; Focal Adhesion Protein-Tyrosine Kinases ; Humans ; Immunohistochemistry ; JNK Mitogen-Activated Protein Kinases ; analysis ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; physiology ; Oligodeoxyribonucleotides, Antisense ; pharmacology ; Protein-Tyrosine Kinases ; analysis ; physiology ; Pulmonary Artery ; cytology

To explore the mechanism of transforming growth factor-beta1 (TGF-beta1) effect on umbilical cord blood mononuclear cells proliferation and apoptosis, 5-bromo-2'-deoxyurine (BrdU) incorporation assay was adopted to detect effect of TGF-beta1 on synthesis of DNA in cells. Western blot method was used to examine effect of TGF-beta1 on expression of cyclin A, Cyclin D1, CDK2 and CDK4 in G1 phase of cell cycle. Giemsa staining and flow cytometry (FCM) were performed to detected effect of TGF-beta1 on cell apoptosis. The results showed that (1) after culture of cells with IMDM containing 10% FBS, 10% FBS + 1 ng/ml TGF-beta1, 10% FBS + 2 ng/ml TGF-beta1 or 10% FBS + 5 ng/ml TGF-beta1 for 12 hours the OD values of TGF-beta1 group were significantly lower than control group (P <0.01); after culture for 24 hours the OD values of 1 ng/ml TGF-beta1 group had no significant difference compared with control group (P >0.05), but the OD values of 2 ng/ml and 5 ng/ml TGF-beta1 groups were significantly lower than control group (P <0.05). (2) 2 ng/ml TGF-beta1 could significantly inhibit the production of cyclin A, cyclin D1, CDK2 and CDK4, the protein levels were significantly lower than control group. (3) when the cells were co-cultured with 2 ng/ml TGF-beta1 for 12 and 24 hours, Giemsa staining and FCM detection could display typical apoptosis, the apoptosis rates were 14.42% and 31.98%, while apoptosis rate in control were 4.71% and 5.76%. It is concluded that TGF-beta1 can inhibit production of G1 cyclins and CDKs of umbilical cord blood mononuclear cells, arrest cells in the G1 phase of cell cycle and induce cell apoptosis. Thus, TGF-beta1 may be an important negative modulator in hematopoiesis.
Apoptosis ; drug effects ; CDC2-CDC28 Kinases ; analysis ; Cell Proliferation ; drug effects ; Cells, Cultured ; Cyclin A ; analysis ; Cyclin D1 ; analysis ; Cyclin-Dependent Kinase 2 ; DNA ; biosynthesis ; Fetal Blood ; cytology ; Humans ; Leukocytes, Mononuclear ; drug effects ; Transforming Growth Factor beta ; pharmacology ; Transforming Growth Factor beta1

OBJECTIVETo reveal the role of Phosphatidylinositol 3-kinases (PI3Ks) in regulating human diploid fibroblast (2BS cell) senescence as well as the possible mechanisms involved.

METHODSUsing a PI3Ks specific inhibitor, LY294002, cell cycle, apoptosis, proliferation, senescence association beta-galactosidase staining as well as senescence association CKIs, p16(INK4) and p21(Cip1) protein expressions were all measured in the low passages of 2BS cells.

RESULTSBoth 25 micro mol/L and 50 micro mol/L concentrations of LY294002 could cause a significant decrease in cells entering into S phase, and this cell cycle of G(1) phase arrest was dose-dependent. Meanwhile, LY294002 contributed to apoptosis, caused 2BS cell growth arrest, and activated senescence association beta-galactosidase (P < 0.05). In addition, LY294002 could induce time-course expressions of p16(INK4) and p21(Cip1) in 2BS cell lines.

CONCLUSIONSPI3Ks inhibitor LY294002 could induce senescence-like changes in 2BS cell lines. Two senescence associated CKIs, p16(INK4) and p21(Cip1), might be involved in this senescence phenotype proceeding in 2BS cell lines.

Cells, Cultured ; Cellular Senescence ; drug effects ; Chromones ; pharmacology ; Cyclin-Dependent Kinase Inhibitor p16 ; analysis ; Cyclin-Dependent Kinase Inhibitor p21 ; Cyclins ; analysis ; Dose-Response Relationship, Drug ; Enzyme Inhibitors ; pharmacology ; Fibroblasts ; drug effects ; physiology ; G1 Phase ; drug effects ; Humans ; Morpholines ; pharmacology ; Phosphatidylinositol 3-Kinases ; antagonists & inhibitors

OBJECTIVETo design DNA microarray and investigate the molecular anti-tumor mechanism of herbs of traditional Chinese medicine.

METHODcDNA microarrays consisting of 56 probes representing 24 human cell cycle genes were constructed, Four anti-hepatocarcinoma herbs including Radix Linderae, Hebra Artemisiae Annuae, Radix Amebiae, Radix Astragli, were chosen. Effects of herbs on SMMC-7721 cell cycle were observed by flow cytometry assay. Effects of herbs on cell cycle gene expression in SMMC-7721 cells were analyzed by comparing hybridization of Dig-Labeled cDNAs from herb-treated cells and cDNAs from untreated cells.

RESULTExpressions of cell cycle geneswere changed in different degrees after herbs treated. Some genes were down-regulated and some genes were up-regulated. The changes in gene expression agreed with the results of flow cytometry assay.

CONCLUSIONThe results suggest that these herbs may have effects on cell cycle and DNA damage checkpoint genes which may be the mechanism of the herbs, and DNA microarray can be used to investigate the biological function of extracts of traditional Chinese medicine.

Antineoplastic Agents, Phytogenic ; isolation & purification ; pharmacology ; Artemisia ; chemistry ; Astragalus membranaceus ; chemistry ; Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Line, Tumor ; Cyclin-Dependent Kinase 4 ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Cyclin-Dependent Kinases ; genetics ; metabolism ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Gene Amplification ; Gene Expression Profiling ; Genes, cdc ; drug effects ; Humans ; Lindera ; chemistry ; Lithospermum ; chemistry ; Liver Neoplasms ; metabolism ; pathology ; Oligonucleotide Array Sequence Analysis ; methods ; Plants, Medicinal ; chemistry ; Proliferating Cell Nuclear Antigen ; genetics ; metabolism ; Proto-Oncogene Proteins ; genetics ; metabolism ; cdc25 Phosphatases ; genetics ; metabolism

Cyclin-dependent kinase inhibitors (CDKI) are negative regulators of cell cycle progression by binding the cyclin-CDK complex and inhibiting the CDK activity. Genetic alteration in the CDKI genes has been implicated for carcinogenesis. To test the genetic alteration in the p27 and p57 genes, KIP family CDKI genes, 30 gastric tumor-normal pairs and 8 gastric cancer cell lines were analyzed for mutations by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). No mutation was detected in these genes although length polymorphisms in the proline-alanine repeat of the p57 gene were detected. When the p27 and p57 mRNAs were analyzed in gastric cancer cell lines by RT-PCR, the p27 mRNA was expressed considerably high in tumor cells but expression of the p57 mRNA was much low in gastric cancer cell lines compared to that of normal cells. The result suggests that inactivation of gene expression rather than mutations in the p57 gene accounts possibly for the involvement of this gene in tumorigenesis of gastric cancer. However, expression of the p27 gene seems to be essential for cell survival.
Cyclin-Dependent Kinases/antagonists & inhibitors* ; DNA Mutational Analysis ; DNA, Neoplasm/analysis ; Enzyme Inhibitors ; Human ; Microtubule-Associated Proteins/metabolism ; Microtubule-Associated Proteins/genetics* ; Nuclear Proteins/metabolism ; Nuclear Proteins/genetics* ; Polymorphism, Single-Stranded Conformational ; RNA, Neoplasm/biosynthesis ; RNA, Neoplasm/analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Stomach Neoplasms/metabolism ; Stomach Neoplasms/genetics* ; Tumor Cells, Cultured

OBJECTIVETo screen and evaluate the active constituents of Chinese medicinal herbs as potent inhibitors of Cdc25 phosphatase.

METHODSThe affinity chromatography purified glutashione-S-transferase/Cdc25A phosphatase fusion protein and Cdc2/cyclin B from the extracts of starfish M phase oocytes are used as the cell cycle-specific targets for screening the antimitotic constituents. We tested 9 extracts isolated from the Chinese medicinal herbs and vegetables including the agents currently used in cancer treatment by measuring the inhibition of Cdc25A phosphatase and Cdc2 kinase activity. The antitumor activity of the extracts was also evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry.

RESULTSCdc25A inhibitory activity and antitumor activity are detected in the extracts isolated from three Chinese medicinal herbs Agrimona pilosa; Herba solani lyrati; Galla chinesis.

CONCLUSIONWe found three extracts isolated from Chinese medicinal herbs have potential inhibitory activity of Cdc25 phosphatase using a highly specific mechanism-based screen assay for antimitotic drug discovery.

Apoptosis ; drug effects ; Cell Cycle Proteins ; antagonists & inhibitors ; metabolism ; Cell Line, Tumor ; Cyclin-Dependent Kinases ; metabolism ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; analysis ; chemistry ; pharmacology ; Humans ; Lethal Dose 50 ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; enzymology ; pathology ; Medicine, Chinese Traditional ; methods ; Mitosis ; drug effects ; Phytotherapy ; methods ; Plants, Medicinal ; chemistry ; cdc25 Phosphatases ; antagonists & inhibitors ; metabolism