OBJECTIVE: To investigate the effect of CDK1 interference regulation of PLK1, Aurora B and TRF1 on the proliferation of leukemia cells. METHODS: The human myelogenous leukemia cell line HL-60 was selected as the research object, and the effect of TRF1 expression and its changes on cell proliferation and cycle was investigated by regulating intracellular CDK1 expression. The objects were divided into 5 groups, including control group, shRNA-NC group, CDK1-shRNA group, pcDNA group and pcDNA-CDK1 group. RT-PCR was used to detect the CDK1 expression of cells in each group; colony formation was used to detect the proliferation of the cells. Western blot was used to detect the expression of CDK1, PLK1, Aurora B, TRF1, and cyclin p53, p27, cyclinA. RESULTS: The phosphorylation level of PLK1, Aurora B and the expression of TRF1 in the CDK1-shRNA group were significantly down-regulated as compared with those in the control group (P<0.05). Compared with the control group, the cells in CDK1-shRNA group showed lower clone formation rate, the increasing of cycle-associated proteins p53 and p27 and the decreasing of cyclinA expression (P<0.05). It was shown that interfered CDK1 expression could inhibit the proliferation of HL-60 cells and prolong the time that they enter mitosis, thereby extending the cell cycle. Compared with the control group, the overexpressed CDK1 in the pcDNA-CDK1 group made the phosphorylation level of PLK1, Aurora B, and TRF1 expression increase significantly (P<0.05), also the colony formation rate (P<0.05). The cycle-related proteins p53 and p27 was down-regulated, while cyclinA expression was up-regulate significantly (P<0.05). The results indicted that overexpressed CDK1 could stimulate adverse reactions, thereby promoting the proliferation of HL-60 cells and shortening the cell cycle. CONCLUSION Knocking out CDK1 can inhibit the phosphorylation of PLK1 and Aurora B and negatively regulate TRF1, thereby inhibiting the proliferation of leukemia cells.
CDC2 Protein Kinase ; Cell Cycle Proteins/genetics* ; Cell Proliferation ; Humans ; Leukemia ; Mitosis ; Phosphorylation ; Proto-Oncogene Proteins/genetics*

OBJECTIVETo investigate the content and activity of M-phase promoting factor (MPF) in pleomorphic adenoma, mucoepidermoid carcinoma, buccal carcinoma and normal tissue, in order to evaluate the role of MPF in the development of tumor and the relationship between MPF and malignant degree.

METHODSThe content and activity of MPF were assessed by immunobloting and Gollicano method.

RESULTSThe cdc2 and cyclinB (two subunits of MPF) were found both in normal and tumor tissues, and their content in tumor was higher than normal tissues. Buccal carcinoma was 64% higher than normal tissues. The activity of MPF in carcinoma was higher than normal tissue and had positive relation with the malignant extent.

CONCLUSIONSThe content and activity of MPF in tumor are higher than normal tissue. PKC can activate MPF. These results show PKC may promote tumor proliferation by activating MPF and also, the activity of MPF has some relation with malignant extent.

CDC2 Protein Kinase ; analysis ; Cyclin B ; analysis ; Humans ; Immunoblotting ; Maturation-Promoting Factor ; analysis ; Mouth ; chemistry ; Mouth Neoplasms ; chemistry ; Protein Kinase C ; physiology

WEE1 is an important factor for histone transcription, chromosome condensation and regulation of cell cycle progression. WEE1 kinase can phosphorylate Cdc2 and down-regulate Cdc2 kinase activity. It can regulate G2 to M phase transition and cell mitosis. It plays a key role in chromosome condensation delay and histone synthesis, suggesting the important functions of WEE1 in the occurrence and development in cancer. At present, a multiple WEE1 inhibitors have been discovered. A great progress has been made in combination of WEE1 inhibitors with DNA damage treatment (chemotherapy or radiotherapy), which makes WEE1 an important target in cancer treatment.
CDC2 Protein Kinase ; metabolism ; Cell Cycle ; Cell Cycle Proteins ; metabolism ; DNA Damage ; Histones ; metabolism ; Humans ; Neoplasms ; metabolism ; Nuclear Proteins ; metabolism ; Phosphorylation ; Protein-Tyrosine Kinases ; metabolism

PURPOSE: The cyclin-dependent kinase 1 (Cdk1) and cyclin B complex performs important roles in the transition from the G2 to M phase in the cell cycle through removal of inhibitory phosphates on Cdk1, and Cdc25B, which is a dual-specific phosphatase, mediates these dephosphorylation events. However, measuring Cdc25B activity by existing methods is hampered by inadequate nonspecific substrates and the need to use a radiolabeled isotope. The present study aimed to develop an improved method with which to properly measure Cdc25B activity using a novel nonradioisotopic assay and Cdc25B overexpression cell lines. MATERIALS AND METHODS: A nonradioisotopic Cdk1 kinase assay, based on Western blotting for retinoblastoma protein and histone H1, was used to analyze Cdc25B activity. Also, stable Cdc25B2 and Cdc25B3 overexpression HeLa cell lines were constructed using the tetracycline-regulated expression system and were applied as a tool for screening for inhibitors of Cdc25B. RESULTS: The present study developed and optimized a nonradioisotopic assay method to properly measure Cdc25B activity. Furthermore, we constructed stable Cdc25B2 and Cdc25B3 overexpression HeLa cell lines for the establishment of a strong assay system with which to evaluate the specificity of Cdc25B inhibitors under conditions similar to the intracellular environment. These methods were confirmed as useful tools for measuring Cdc25B activity. CONCLUSION: The nonradioisotopic Cdk1 kinase assay and Cdc25B overexpression cell lines developed in this study can be conveniently used as tools for screening inhibitors of Cdc25B phosphatase as anticancer drugs.
Blotting, Western ; CDC2 Protein Kinase ; cdc25 Phosphatases ; Cell Cycle ; Cell Division ; Cell Line* ; Cyclin B ; HeLa Cells ; Histones ; Humans ; Mass Screening* ; Methods ; Phosphates ; Retinoblastoma Protein ; Sensitivity and Specificity

OBJECTIVE: To investigate the expression of eIF3P170, cdc2, cyclinB1 and cyclinD1 in developing cardiac myocytes, and the correlation between eIF3P170 with cdc2, cyclin D1, and cyclin B1 in mice. METHODS: Mouse cardiac myocytes were obtained at different time points. RT-PCR was employed to detect the expression of eIF3P170, cdc2, cyclin D1 and cyclin B1 mRNA. RESULTS: Expressions of eIF3P170, cdc2, cyclinD1 and cyclinB1 mRNA were higher in the embryonic Day 13, 15, 18 and postnatal Day 1, 2, 3, 5. Expressions at postnatal Day 5 reached the highest (all P values<0.05 vs other time points), and then the expressions of these genes gradually decreased to the weakest at postnatal Day 30 (all P values<0.05 vs other time points). The mRNA expression of eIF3P170 was positively correlated with cdc2, cyclin D1 and cyclin B1 mRNA expression respectively. CONCLUSION The mRNA expressions of eIF3 P170, cdc2, cyclin D1 and cyclin B1 in the embryo and the early life after birth are high. They reach the maximum at postnatal Day 5, then gradually decreased.
Animals ; CDC2 Protein Kinase ; metabolism ; Cell Cycle ; Cyclin B1 ; metabolism ; Cyclin D1 ; metabolism ; Eukaryotic Initiation Factor-3 ; metabolism ; Mice ; Myocytes, Cardiac ; cytology ; metabolism ; RNA, Messenger

OBJECTIVE: To investigate the clinical characteristics, diagnosis and treatment of 1 case EBV negative extranodal NK/T cell lymphoma (ENKTL) patients. METHODS: The clinical manifestations, diagnosis and treatment of one case ENKTL patients with EBV negative were analyzed retrospectively. RESULTS: A 46-year-old woman diagnosed as positive for exosanal NK/T cell lymphoma (EBER CONCLUSION EBV negative ENKTL is rare in clinic and easy to be misdiagnosed, so it should be distinguished from peripheral T cell lymphoma. This case was treated with EBV positive ENKTL regimen, with good short-term efficacy.
CDC2 Protein Kinase ; Cell Proliferation ; Female ; Humans ; Leukemia ; Lymphoma, Extranodal NK-T-Cell ; Middle Aged ; Positron Emission Tomography Computed Tomography ; Retrospective Studies

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: Recent studies have suggested that p53 regulates the G2 checkpoint in the cell cycle and this function is required for the maintenance of genomic integrity. In this study, we addressed a role of p53 in escaping from cell cycle G2 arrest following DNA damage. MATERIALS AND METHODS: Cell cycle checkpoint arrest in the human colon cancer cell line HCT116 and its derivatives carry p53 or p21 deletions, were examined by FACS analysis, immunoprecipitation, Western blot and IP-kinase assay. RESULTS: While the cells with functional p53 were arrested at both the G1 and G2 checkpoints, the p53-deficient cells failed to arrest at G1, but they were arrested at G2. However, the p53-deficient cells failed to sustain G2 checkpoint arrest and they entered mitosis earlier than did the p53-positive cells and so this resulted in extensive cell death. Cdc2 kinase becomes reactivated in p53-deficient cells in association with entry into mitosis, but not in the p53-positive cells. Upon DNA damage, the p21-deficient cells, like the p53-negative cells, not only failed to repress cdk2- dependent NF-Y phosphorylation, but they also failed to repress the expression of such cell cycle G2-regulatory genes as cdc2, cyclin B, RNR-R2 and cdc25C, which have all been previously reported as targets of NF-Y transcription factor. CONCLUSION: p53 is essential to prevent immature escaping from cell cycle G2 checkpoint arrest through p21-mediated cdk2 inactivation, and this leads to inhibition of cdk2-dependent NF-Y phosphorylation and NF-Y dependent transcription of the cell cycle G2-rgulatory genes, including cdc2 and cyclin B.
Blotting, Western ; CCAAT-Binding Factor ; CDC2 Protein Kinase ; Cell Cycle Checkpoints ; Cell Cycle* ; Cell Death ; Cell Line ; Colonic Neoplasms ; Cyclin B ; DNA Damage ; G2 Phase ; Humans ; Immunoprecipitation ; Mitosis ; Phosphorylation* ; Phosphotransferases ; Transcription Factors ; Tumor Suppressor Protein p53 ; United Nations*

OBJECTIVE: The BCL2 family proteins are critical mediators of cellular apoptosis and, as such, have been implicated as determinants of cancer cell chemo-sensitivity. Recently, it has been demonstrated that the phosphorylation status of the BCL2 antagonist of cell death (BAD) protein may influence ovarian cancer (OVCA) cell sensitivity to cisplatin. Here, we sought to evaluate how kinase and phosphatase components of the BAD apoptosis pathway influence OVCA chemo-sensitivity. METHODS: Protein levels of cyclin-dependent kinase 1 (CDK1) and protein phosphatase 2C (PP2C) were measured by immunofluorescence in a series of 64 primary advanced-stage serous OVCA patient samples. In parallel, levels of cAMP-dependent protein kinase (PKA), AKT, and PP2C were quantified by Western blot analysis in paired mother/daughter platinum-sensitive/resistant OVCA cell lines (A2008/C13, A2780S/A2780CP, Chi/ChiR). BAD pathway kinase CDK1 was depleted using siRNA transfection, and the influence on BAD phosphorylation and cisplatin-induced apoptosis was evaluated. RESULTS: OVCA patient samples that demonstrated complete responses to primary platinum-based therapy demonstrated 4-fold higher CDK1 (p<0.0001) and 2-fold lower PP2C (p=0.14) protein levels than samples that demonstrated incomplete responses. Protein levels of PP2C were lower in the platinum-resistant versus that shown in the platinum-sensitive OVCA cell line sub-clones. Levels of PKA were higher in all platinum-resistant than in platinum-sensitive OVCA cell line sub-clones. Selective siRNA depletion of CDK1 increased sensitivity to cisplatin-induced apoptosis (p<0.002). CONCLUSION: BAD pathway kinases and phosphatases, including CDK1 and PP2C, are associated with OVCA sensitivity to platinum and may represent therapeutic opportunities to enhance cytotoxic efficacy.
Apoptosis ; Blotting, Western ; CDC2 Protein Kinase ; Cell Death ; Cell Line ; Cisplatin ; Cyclic AMP-Dependent Protein Kinases ; Fluorescent Antibody Technique ; Humans ; Ovarian Neoplasms ; Phosphoprotein Phosphatases ; Phosphoric Monoester Hydrolases ; Phosphorylation ; Phosphotransferases ; Platinum ; Proteins ; RNA, Small Interfering ; Transfection

PURPOSE: Cell cycle progression is regulated by interactions of specific cyclins and cyclin dependent kinases (CDKs) at the G1-S and G2-M checkpoints and cell cycle deregulation plays a major role in carcinogenesis of human cancers. PATIENTS AND METHODS: To investigate the role of cell cycle regulators in the pathogenesis and progression of human gastric cancers, 23 cases of gastric carcinomas were examined for the expression of cyclin B1, p34cdc2, p27(Kip1) and p53 by immunohistochemical methods, and gene expression was correlated with various clinicopathologic findings. RESULTS: Out of 23 cases studied, cyclin B1 was diffusely expressed in 20 cases (87.0%), p34cdc2 in 14 cases (60.9%) and p53 in 12 cases (52.2%), whereas in normal gastric tissues, cyclin B1 and p34cdc2 were weakly expressed and p53 was not expressed. In contrast, p27(Kip1) was expressed in only 8.7% of gastric carcinomas compared with 78.3% of normal gastric tissues. There was correlation between the expression of cyclin B1 and expression of p34cdc2 (p=0.002), between the expression of cyclin B1 and loss of p27(Kip1) (p=0.025), and between the expression of p34cdc2 and loss of p27(Kip1) (p=0.065). In addition, expression of cyclin B1 was correlated with regional lymph node metastasis (p=0.032). CONCLUSION: Our results indicate that cyclin B1 and p34cdc2 are involved in the genesis or progression of gastric cancers. Furthermore, overexpression of cyclin B1 may play an important role in lymph node metastatic potential of gastric cancer. Thus, abnormal expression of cyclin B1 and CDKs, overexpression of p53 and loss of p27(Kip1) expression may play important roles in human gastric carcinogenesis.
Adult ; Aged ; CDC2 Protein Kinase/*metabolism ; Cyclin B/*metabolism ; Female ; Humans ; Intracellular Signaling Peptides and Proteins/*metabolism ; Male ; Middle Aged ; Prognosis ; Stomach Neoplasms/*diagnosis/metabolism ; Tumor Suppressor Protein p53/*metabolism