OBJECTIVETo explore the core mechanism of cell cycle compensation using a mathematical model.

METHODSA set of ordinary differential equations were used to describe the interactions between the core cell cycle molecules. Continuous and cyclic changes of the concentrations of these molecules were computed to capture the discrete events of molecular interactions.

RESULTSThe calculated molecule concentrations and captured signaling events agreed with the experimental results.

CONCLUSIONE2F transcription factor 1 is the pivotal element linking the positive and negative feedbacks and regulating G1/S and G2/M phase compensation.

Animals ; Cell Cycle ; Drosophila ; cytology ; E2F1 Transcription Factor ; Feedback, Physiological ; Models, Theoretical

OBJECTIVETo investigate the expression of E2F1 gene in patients with acute leukemia(AL) and its clinical significance.

METHODSSeventy-two AL patients treated in March 2015 -March 2016 in our hospital were selected, and 24 healthy people were selected as controls. RT-PCR and Western blot were applied to determine the level of E2F1 gene transcription and expression, and the statistical analysis was performed to reveal the clinical value of E2F1 gene.

RESULTSThe relative expression levels of E2F1 gene and protein in bone marrow of AL patients was higher than that in control group (P<0.05). The levels of WBC, β-MG and LDH in the patients with high expression of E2F1 gene were higher than those in patients with low expression of E2F1 gene(P<0.05), but the E2F1 gene expression did not correlate with sex, fever, fatigue, bone marrow blast ratio, peripheral blood blasts ratio (P>0.05). The complete remission (CR) of patients with low expression of E2F1 was significantly higher than that of patients with high expression of E2F1(P<0.05). And the drug resistance in the patients with low expression of E2F1 gene was lower than that of patients with high expression of E2F1 gene (P<0.05). The expression level of E2F1 gene decreased significantly in patients with symptomatic remission after treatment (P<0.05). The expression levels of E2F1 gene in M1, M2 and M5 patients decreased significantly after treatment (P<0.05). Kaplan-Meier survival analysis showed that OS and DFS in the patients with low expression of E2F1 gene were higher than those in patients with high expression (P<0.05). Multivariate Cox regression analysis showed that the age and E2F1 gene were the independent influencing factors of OS (P<0.05); the sex and E2F1 gene were the dependent factors of DFS (P<0.05).

CONCLUSIONThe expression level of E2F1 gene in patients with AL has been found to be higher, the higher level of E2F1 gene closely relates with AL patients, E2F1 gene can be used as a biological target for the clinical treatment of AL.

Acute Disease ; Blood Cell Count ; Bone Marrow ; E2F1 Transcription Factor ; Humans ; Leukemia ; Prognosis ; Remission Induction

Previously, we have reported that transcription factor E2F1 expression is up-regulated in approximately 95% of small cell lung cancer tissue samples and closely associated with invasion and metastasis, but few studies have investigated specific target genes regulated by E2F1 in this disease. The aim of this study was to clarify the target genes controlled by E2F1 in the small cell lung cancer cell line H1688. The results of chromatin immunoprecipitation sequencing (ChIP-seq) showed that total 5 326 potential target genes were identified, in which 4 700 were structural genes and 626 long non-coding RNAs (lncRNAs). Gene Ontology (GO) and enrichment map analysis results indicated that these target genes were associated with three main functions: (1) cell cycle regulation, (2) chromatin and histone modification, and (3) protein transport. MEME4.7.0 software was used to identify the E2F1 binding DNA motif, and six motifs were discovered for coding genes and lncRNAs. These results clarify the target genes of E2F1, and provide the experimental basis for further exploring the roles of E2F1 in tumorigenesis, development, invasion and metastasis, recurrence, and drug resistance in small cell lung cancer.
Chromatin ; E2F1 Transcription Factor ; Gene Expression Regulation, Neoplastic ; Humans ; Lung Neoplasms ; Small Cell Lung Carcinoma ; Up-Regulation

OBJECTIVETo investigate the correlations between p14(ARF) and E2F-1, and the role of their alterations in the tumorigenesis of the lung cancer in Gejiu and Xuanwei regions in Yunnan Province for providing the important experiment basis in revealing the molecular mechanism and looking for new markers for early diagnosis of lung cancer.

METHODSThe expression of p14(ARF) and E2F-1 was detected at theirs protein level by Immunohistochemistry S-P method in 30 specimens of lung cancer of Gejiu tin miners, 30 specimens of lung cancer of Xuanwei peasants and 20 specimens of normal lung tissue. E2F-1 mRNA was detected by ISH in 25 specimens of lung cancer of Gejiu tin miners, 25 specimens of lung cancer of Xuanwei peasants and 10 specimens of normal lung tissue. The positive signals were quantitatively analysed by HPIAS-100.

RESULTSThe positive unit (PU) of p14(ARF) and E2F-1 was 16.44 +/- 4.85 and 47.39 +/- 5.43 in Gejiu group, and 16.79 +/- 3.55 and 48.15 +/- 9.11 in Xuanwei group. Expression of p14(ARF) and E2F-1 protein in lung cancer of Gejiu and Xuanwei were statistically different compared with that in the normal lung (P < 0.01) respectively; The PU of E2F-1 mRNA was 48.58 +/- 7.75 in Gejiu group, and 49.41 +/- 8.53 in Xuanwei group, which was higher than that in normal tissue group. The differences were significant (P < 0.01). There was positive correlation between the expression of E2F-1 protein and E2F-1 mRNA in Gejiu group, Xuanwei group and normal group (P < 0.01, r = 0.833). The expression of p14(ARF) protein was significantly negatively correlated with the expression of E2F-1 protein (P < 0.01, r = -0.830).

CONCLUSIONThere is the over-expression of E2F-1 gene and the deletion of p14(ARF) gene in the tumorigenesis of the lung cancer in Gejiu and Xuanwei regions in Yunnan Province. Over-expression of E2F-1 protein in lung cancer may be caused by enhanced transcription.

China ; E2F1 Transcription Factor ; genetics ; metabolism ; Female ; Humans ; Lung Neoplasms ; metabolism ; Male ; RNA, Messenger ; genetics ; Tumor Suppressor Protein p14ARF ; metabolism

OBJECTIVETo investigate the roles of activated protein 1 (AP-1) in cell cycle changes on human embryo lung fibroblasts (HELF) induced by benzo (a) pyrene [B (a) P], and relationships between AP-1 and cyclin D1/CDK4-E2F-1/4.

METHODSCells transfected with AP-1 luciferase reporter plasmid (AP-H) were cultured with serum-free RPMI1640 for 48 h, and treated with 2 micromol/L B (a) P for 24 h. AP-1 relative activity was detected by luciferase assay. Changes of cell cycle and the expression of cyclin D1, CDK4 and E2F-1/4 were checked using the flow cytometer and Western blot assay.

RESULTSAfter B (a) P was treated for 24 h, the ratio of G1 phase cells (71 +/- 2)% was decreased to (48 +/- 3)% (P < 0.05), and an increase was observed in the ratio of S phase. AP-1 activity and cyclin D1/E2F-1 expression were increased significantly, but CDK4/E2F-4 expression did not change after B (a) P treatment. When AP-1 activity was inhibited by curcumin, decreases of G1 phase in response to B (a) P treatment were blocked, and overexpression of cyclin D1/E2F-1 was attenuated, but CDK4/E2F-4 expression was not changed significantly.

CONCLUSIONAP-1 is involved in B (a) P induced cell cycle changes, and is the upstream signals of cyclin D1/E2F-1, but not CDK4/E2F-4.

Benzo(a)pyrene ; toxicity ; Cell Cycle ; drug effects ; Cells, Cultured ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 4 ; metabolism ; E2F1 Transcription Factor ; metabolism ; E2F4 Transcription Factor ; metabolism ; Fibroblasts ; cytology ; metabolism ; Humans ; Transcription Factor AP-1 ; genetics ; metabolism ; Transfection

BACKGROUND: Disturbances of the cell cycle regulatory proteins are key events underlying the development and/or progression of human malignancies. The aim of this study was to evaluate the expression of G1/S cell cycle regulatory proteins in ovarian epithelial tumor. METHODS: We simultaneously evaluated the expression of cyclin D1, cyclin E, CDK4, CDK2, p16, Rb, E2F1, p53 and the Ki67 labelling index (LI) by immunohistochemical methods in 148 cases of ovarian epithelial tumor of the benign (n=47), borderline (n=29), and malignant type (n=72). RESULTS: The expression of cyclin E, CDK2, p16, Rb, E2F1, p53 and the Ki67 LI gradually increased from the benign type, through the borderline type, to the malignant tumors. Between the borderline and malignant tumors, the increased expression of cyclin E, E2F1, and p53, and the decreased expression of Rb were significantly associated with malignancy. The reduced Rb expression and the increased E2F1 expression were correlated with the FIGO stage and the histologic grade in the malignant ovarian epithelial tumors. CONCLUSIONS: Cyclin E, E2F1, and p53 overexpressions and the loss of Rb are the important components during carcinogenesis of ovarian epithelial tumors. Our results suggest that in- creased expression of E2F1 should be considered as a new parameter for the prognosis of patients with malignant ovarian epithelial tumors.
Carcinogenesis ; Cell Cycle Proteins* ; Cell Cycle* ; Cyclin D1 ; Cyclin E ; Cyclins ; E2F1 Transcription Factor ; Female ; Humans ; Neoplasms, Glandular and Epithelial ; Ovary ; Prognosis

OBJECTIVETo study the role of transcription factor E2F1 in the transcription of KIR3DL1 promoter, and to identify its molecular mechanism of regulation of KIR3DL1 gene expression.

METHODSThe mutant promoter fragment of KIR3DL1 gene was amplified from genomic DNA of K562 cells by PCR. The PCR product was cloned into pGL3-basic reporter vector to construct KIR3DL1 promoter-luciferase reporter plasmid (PLRP). The binding of E2F1 to KIR3DL1 promoter was detected by chromatin immunoprecipitation (CHIP) assays. The KIR3DL1 PLRP construction was transfected into K562 cells using cationic liposome SuperFect. The binding of E2F1 to the construction was detected by CHIP assays and reporter activity was quantitated by the dual-luciferase reporter assay system. The mammalian expression vector containing E2F1 cDNA was co-transfected into K562 cells with wild-type KIR3DL1 PLR construction and reporter activity was quantitated.

RESULTSThe mutant KIR3DL1 PLR recombinant was constructed successfully and a naturally point mutation (TTTGGCGC-->TTCGGCGC) within a putative E2F1 binding site in the KIR3DL1 promoter region was authenticated by DNA sequencing. E2F1 absolutely could not bind to the mutant KIR3DL1 promoter in K562 cells, but could bind to the wild-type one in NK-92MI cells. The binding of E2F1 to the mutant KIR3DL1 PLR construction was partially reserved, however, its relative luciferase activity was decreased by 50% than that of wild-type. On the other hand, when co-transfected with E2F1 mammalian expression vector, the relative luciferase activity of wild-type construction was increased, over 2-fold higher than that of control group.

CONCLUSIONE2F1 participates in the regulation of the transcriptional activation of KIR3DL1 gene. The number of CpG dinucleotide and methylation pattern within the E2F1 binding site probably influence the binding of E2F1 to target sequence.

E2F1 Transcription Factor ; genetics ; Gene Expression Regulation ; Genetic Vectors ; Humans ; K562 Cells ; Promoter Regions, Genetic ; genetics ; Receptors, KIR3DL1 ; genetics ; Transcriptional Activation ; Transfection

OBJECTIVE: To determine the dynamic expression of E2F1 in lung of premature rats with hyperoxia-induced chronic lung disease and the relation between E2F1 and pulmonary fibrosis. METHODS: Premature Wistar rats at 21 days gestation were randomly and equally divided into a hyperoxia group and a room air group. The hyperoxia group was continuously exposed to hyperoxia (90%) while the air group in room air. Lung tissues in the 2 groups were obtained at 3, 7 and 14 days after exposing to either room air or hyperoxia. The changes of pulmonary histopathology at different time points were observed by hematoxylin and eosin staining; the severity of pulmonary fibrosis was evaluated; and the expression of E2F1 in lung tissue was detected by immunohistochemistry and Western blot. RESULTS: After 3 days of hyperoxia, no significant interstitial fibrosis was observed; while after 7 days in the hyperoxia group, interstitial fibrosis was observed. These changes became more obvious after 14 days of prolonged hyperoxia exposure. No significant difference in the expressions of E2F1 protein was found between the hyperoxia group and the room air group 3 days postnatally (P>0.05). The expression of E2F1 in the hyperoxia group significantly increased 7 days and 14 days postnatally (P<0.05, P<0.01). CONCLUSION Abnormality of E2F1 expression is involved in the pathological process of the proliferation of lung fibroblasts in hyperoxia-induced chronic lung disease neonatal rats, and it plays an important role in lung fibrosis.
Animals ; Animals, Newborn ; E2F1 Transcription Factor ; metabolism ; Hyperoxia ; metabolism ; pathology ; Immunohistochemistry ; Lung ; pathology ; Lung Diseases ; metabolism ; pathology ; Pulmonary Fibrosis ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar

OBJECTIVETo study the role of E2F1/4 pathway in vitamin C reversing benzo (a) pyrene [B (a) P]-induced changes of cell cycle in human embryo lung fibroblasts (HELF) and the relationship between E2F1 and cyclin D1/CDK4.

METHODSThe stable transfectants, HELF transfected with antisense cyclin D1 and antisense CDK4, were established to detect the relationship of signaling pathway. Cells were cultured and pretreated with vitamin C before stimulation with B (a) P for 24 hours. The expression levels of cyclin D1, CDK4, E2F1 and E2F4 were determined by Western blot and the band intensity was analysed as the relative value to control by using the Gel-Pro 3.0 software. Flow Cytometric Analysis was employed to detect the distributions of cell cycle.

RESULTSB (a) P significantly elevated the expression levels of cyclin D1, CDK4, E2F1 and E2F4 in HELF cells. Vitamin C decreased the expression levels of above proteins in B (a) P-stimulated HELF cells. The expression levels of these proteins in B (a) P-treated above transfectants were lower than those in B (a) P-treated HELF cells. The expression levels of above proteins with vitamin C combined with antisense cyclin D1 were decreased as compared to those with antisense cyclin D1 alone. B (a) P increased the percentage of S phase as compared to the controls [(41.1 +/- 0.2)% vs (33.5 +/- 3.2)%, P < 0.05]. Both vitamin C [(33.2 +/- 0.6)% vs (41.1 +/- 0.2)%, P < 0.05] and antisense cyclin D1 [(31.2 +/- 1.3)% vs (41.1 +/- 0.2)%, P < 0.05] suppressed the changes of cell cycle induced by B (a) P. Vitamin C combined with antisense CDK4 markedly suppressed B (a) P-induced changes of cell cycle as compared to those with antisense CDK4 alone.

CONCLUSIONVitamin C might reserve the B (a) P-induced changes of cell cycle via intracellular signaling pathway of cyclin D1-CDK4/E2F-1/4.

Ascorbic Acid ; pharmacology ; Benzo(a)pyrene ; antagonists & inhibitors ; toxicity ; Cell Cycle ; drug effects ; Cyclin D1 ; metabolism ; E2F1 Transcription Factor ; metabolism ; E2F4 Transcription Factor ; metabolism ; Humans ; Lung ; cytology ; embryology ; Signal Transduction

OBJECTIVETo investigate the variation in expression of ARHI, STAT3 and E2F1 and the correlation among them during carcinogenesis of ovarian serous carcinoma.

METHODSImmunohistochemical staining was used to detect the expression of ARHI, STAT3 and E2F1 in samples of 25 normal ovaries, 35 ovarian serous cystadenomas, 18 borderline serous cystadenomas and 56 ovarian serous carcinomas. The variation in expression of the three genes and relationship among them were analyzed.

RESULTSARHI expression was detected in 22 of 25 (88.0%) normal ovaries and 30 of 35 (85.7%) cystadenomas, but only in 10 of 18 (55.6%) borderline serous cystadenomas and 22 of 56 (39.3%) ovarian serous carcinomas, significantly lower than that in the normal ovaries and ovarian serous cystadenomas (P < 0.05). STAT3 expression was found in 14 of 18 (77.8%) borderline serous cystadenomas and 49 of 56 (87.5%) ovarian serous carcinomas, significantly higher than that in the normal ovaries and ovarian serous cystadenomas (P < 0.05). To compare with E2F1 expression in the normal ovaries, serous cystadenomas and borderline serous cystadenomas, E2F1 expression in 46 of 56 (82.1%) ovarian serous carcinomas was significantly higher (P < 0.05). It was found that the expression of ARHI was inversely correlated with that of STAT3 and E2F1.

CONCLUSIONOur findings indicate that ARHI expression is down-regulated, but STAT3 and E2F1 expressions are up-regulated, with an inverse correlation between ARHI and STAT3 in the carcinogenesis of ovarian serous carcinoma.

Adult ; Aged ; Cystadenocarcinoma, Serous ; metabolism ; pathology ; Cystadenoma, Serous ; metabolism ; pathology ; E2F1 Transcription Factor ; metabolism ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Immunohistochemistry ; Middle Aged ; Ovarian Neoplasms ; metabolism ; pathology ; Ovary ; metabolism ; pathology ; STAT3 Transcription Factor ; metabolism ; rho GTP-Binding Proteins ; metabolism