Expression of E2F1 Gene in Acute Leukemia and Its Clinical Significance / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the expression of E2F1 gene in patients with acute leukemia(AL) and its clinical significance.</p><p><b>METHODS</b>Seventy-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.</p><p><b>RESULTS</b>The 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).</p><p><b>CONCLUSION</b>The 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.</p>

Target genes regulated by transcription factor E2F1 in small cell lung cancer / 生理学报

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.

Total triterpenoids from Ganoderma Lucidum suppresses prostate cancer cell growth by inducing growth arrest and apoptosis / 华中科技大学学报（医学）（英德文版）

In this study, one immortalized human normal prostatic epithelial cell line (BPH) and four human prostate cancer cell lines (LNCaP, 22Rv1, PC-3, and DU-145) were treated with Ganoderma Lucidum triterpenoids (GLT) at different doses and for different time periods. Cell viability, apoptosis, and cell cycle were analyzed using flow cytometry and chemical assays. Gene expression and binding to DNA were assessed using real-time PCR and Western blotting. It was found that GLT dose-dependently inhibited prostate cancer cell growth through induction of apoptosis and cell cycle arrest at G1 phase. GLT-induced apoptosis was due to activation of Caspases-9 and -3 and turning on the downstream apoptotic events. GLT-induced cell cycle arrest (mainly G1 arrest) was due to up-regulation of p21 expression at the early time and down-regulation of cyclin-dependent kinase 4 (CDK4) and E2F1 expression at the late time. These findings demonstrate that GLT suppresses prostate cancer cell growth by inducing growth arrest and apoptosis, which might suggest that GLT or Ganoderma Lucidum could be used as a potential therapeutic drug for prostate cancer.

Reversion of multidrug resistance of human gastric cancer SGC7901/DDP cells by E2F-1 gene silencing / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effects of E2F-1 gene silencing on multidrug resistance of human gastric cancer SGC7901/DDP cells and its possible mechanisms.</p><p><b>METHODS</b>Gastric cancer SGC7901/DDP cells were seeded in 6 well plates and divided into three groups: the experimental group, blank control and the negative control groups. For the experimental group, the SGC7901/DDP cells were transfected with recombinant lentivirus vector (Lv-shRNA-E2F-1), while the negative control with an control lentiviral vector (Lv-shRNA-NC) and the blank control with no treatment. The E2F-1 protein level was analyzed by Western blot. MTT assay was used to detect the half maximal inhibitory concentration (IC50) of three chemotherapy drugs including adriamycin, 5-fluorouracil (5-Fu) and cisplatine (DDP) of the three cell groups. Flow cytometry (FCM) was used to detect the pump-out rate of adriamycin and apoptosis rate of the three cell groups. Semi-quantitative RT-PCR and Western blot were also used to detect the protein and mRNA levels of multidrug resistance-associated genes (MDR1, MRP) and apoptosis-related genes (c-Myc, Skp2, cyclinD1).</p><p><b>RESULTS</b>The expression of E2F-1 protein in the experimental group was significantly lower than that in the negative control and blank control groups (0.794 ± 0.033 vs. 1.487 ± 0.082 vs. 1.511 ± 0.084, P < 0.01). The IC50 of the three chemotherapy drugs (adriamycin, 5-Fu and cisplatine) in the experimental group was significantly lower than that of the negative control and blank control groups, respectively (P < 0.01). Compared with the negative control and blank control groups, the pump-out rate of adriamycin of the experimental group was significantly declined [(0.16 ± 0.01)% vs. (0.37 ± 0.01)% vs. (0.35 ± 0.02)%, P < 0.01]. However, the apoptosis rate of the experimental group was significantly higher than that of the negative control and blank control groups [(33.82 ± 1.26)% vs. (17.34 ± 0.81)% vs. (13.16 ± 1.06)%, P < 0.01]. The results of RT-PCR and Western blot assays showed that mRNA and protein expressions of five genes (MDR1, MRP, CyclinD1, c-Myc, Skp2) in the experimental group were significantly lower than that in the negative control and blank control groups, respectively (P < 0.01).</p><p><b>CONCLUSIONS</b>E2F-1 gene silencing enhances the chemosensitivity of gastric cancer SGC7901/DDP cells to the chemotherapeutic drugs, directly or indirectly downregulated the expression of MDR1 and MRP, and finally reverses the multidrug resistance of the gastric cancer cells. The mechanism may be associated with the suppression of cyclinD1, c-Myc and Skp2.</p>

siRNA-mediated CDK6 knockdown suppresses nasopharyngeal carcinoma cell growth and cell cycle transition in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the effect of small interfering RNA (siRNA)-mediated suppression of CDK6 expression on the proliferation and cell cycles of nasopharyngeal carcinoma (NPC) cells in vitro.</p><p><b>METHODS</b>QRT-PCR was used to examine the differential expression of CDK6 in 30 NPC tissues and 18 normal nasopharyngeal tissues. A siRNA targeting CDK6 was transfected in NPC CNE2 cells, and MTT assay and flow cytometry were used to analyze the changes in cell proliferation and cell cycle distribution. Western blotting was used to examine the expressions of the cell cycle-related factors.</p><p><b>RESULTS</b>Compared with normal nasopharyngeal tissues, NPC tissues showed an increased expression of CDK6 mRNA. Knocking down CDK6 expression obviously inhibited tumor cell growth and cell cycle transition from G1 to S phase and caused reduced expressions of CDK4, CCND1, and E2F1 and enhanced expression of the tumor suppressor p21.</p><p><b>CONCLUSION</b>NPC tissues overexpress CDK6. Knocking down CDK6 expression inhibits the growth and cell cycle transition of NPC cells in vitro by inhibiting the expressions of CDK4, CCND1, and E2F1 and upregulating tumor suppressor p21 expression.</p>

EZH2 gene silenced by siRNA suppresses the growth and invasion of endometrial carcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the effects on cell proliferation and invasion as well as molecular basis after suppressing EZH2 expression in endometrial carcinoma cells by using siRNAs.</p><p><b>METHODS</b>RT-PCR was used to examine the expression of EZH2 in endometrial carcinoma and their paracancerous tissues. SiRNAs targeting to EZH2 were transfected to endometrial carcinoma cells, and MTT, FACS, and boyden assays were utilized to examine cell proliferation, cell cycle change, and cell invasion. Finally, the molecular mechanisms of EZH2 on cell function alteration were investigated.</p><p><b>RESULTS</b>Compared with paracancerous tissues, increased expression trend of EZH2 mRNA was showed in endometrial carcinoma tissues. Further, knocking down EZH2 expression inhibited cell growth, cell cycle transition from G1 to S phase, and cell invasion ability. Molecular basis indicated that suppression of EZH2 downregulated the expression of E2F1 and MMP9 and upregulated tumor suppressor p21 expression.</p><p><b>CONCLUSION</b>EZH2 expression is increased in endometrial carcinoma tissues. Knocking down EZH2 expression suppresses the cell growth, cell cycle transition and cell invasion by downregulated E2F1 and MMP9, and upregulated tumor suppressor p21 expression.</p>

A quantitative investigation of E2F1-regulated cell cycle compensation mechanism / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the core mechanism of cell cycle compensation using a mathematical model.</p><p><b>METHODS</b>A 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.</p><p><b>RESULTS</b>The calculated molecule concentrations and captured signaling events agreed with the experimental results.</p><p><b>CONCLUSION</b>E2F transcription factor 1 is the pivotal element linking the positive and negative feedbacks and regulating G1/S and G2/M phase compensation.</p>

Inhibitory effect of E2F-1-silencing lentivirus vector on chemoresistance of subcutaneous human gastric cancer in nude mice / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the effects of E2F-1-silencing lentivirus vector on the growth and chemoresistance of subcutaneous human gastric cancer in nude mice.</p><p><b>METHODS</b>Thirty-six nude mice were inoculated subcutaneously with chemoresistant SGC-7901/DDP cells to establish subcutaneous tumor models of gastric carcinoma. The mice were randomly divided into E2F-1/RNAi-LV group, LV-scrRNAi group and PBS group (n = 12). E2F-1/RNAi-LV, LV-scrRNAi or PBS (0.1 ml per time) was injected into the mice, respectively, every two days. The nude mice received an intraperitoneal injection of cisplatin (25 mg/kg) every two days. The tumor volume was measured and histopathological changes of the tumors were observed by HE staining. The expressions of E2F-1, c-Myc, survivin, MDR1 and MRP were detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Apoptosis in tumor xenografts was determined by in situ TUNEL labeling technique.</p><p><b>RESULTS</b>The mean tumor growth rate of the E2F-1/RNAi-LV group was significantly slower than that of the LV-scrRNAi and control groups (P < 0.05). The tumor volume of the E2F-1/RNAi-LV group was (745.13 ± 154.42)mm(3), significantly lower than that of the LV-scrRNAi and PBS groups (P < 0.05). Compared with that in the LV-scrRNAi and PBS groups, the expressions of mRNA and protein of E2F-1, c-Myc, survivin, MDR1 and MRP were significantly decreased in the E2F-1/RNAi-LV group (P < 0.05). The apoptotic rate in the E2F-1/RNAi-LV treatment group was (27.5 ± 9.7)%, significantly higher than (7.0 ± 1.1)% in the LV-scrRNAi group and (7.3 ± 1.2)% in the PBS group (P < 0.05).</p><p><b>CONCLUSION</b>Intra-tumoral injection of E2F-1/RNAi-LV shows significantly inhibitory effect on the tumor growth and chemoresistance of subcutaneous human gastric cancer in nude mice.</p>

Effects of E2F-1 gene silencing on cisplatin chemosensitivity of human gastric cancer SGC-7901/DDP cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of E2F-1 gene silencing on the chemosensitivity of human gastric cancer SGC-7901/DDP cells to cisplatin and explore the underlying mechanism.</p><p><b>METHODS</b>Gastric cancer SGC-7901/DDP cells were transfected with the recombinant lentivirirus vector Lv-shRNA-E2F-1 for E2F-1 gene silencing, with cells transfected with the control recombinant lentivirirus vector Lv-shRNA-NC as the negative control. MTT assay was used to evaluate cisplatin chemosensitivity of the cells, and the cell apoptosis rate and cell cycle distribution were detected by flow cytometry. The mRNA and protein expressions of E2F-1 and apoptosis-related genes (survivin and Bcl-2) were detected by RT-PCR and Western blotting.</p><p><b>RESULTS</b>MTT assay showed that the IC50 of cisplatin was significantly lowered in Lv-shRNA-E2F-1-transfected cells compared with the negative and blank control cells (P<0.05). Lv-shRNA-E2F-1 transfection caused significant cell cycle arrest in G0/G1 phase and induced obvious cell apoptosis. Compared with Lv-shRNA-NC group and the blank control group, Lv-shRNA-E2F-1 group showed significantly lowered expressions of E2F-1 mRNA by 45.0% and 41.3% and E2F-1 protein by 66.7% and 70.5%, survivin mRNA by 30.3% and 28.7% and survivin protein by 56.5% and 53.6%, and Bcl-2 mRNA by 76.6% and 76.8% and Bcl-2 protein by 74.6% and 79.9%, respectively. No significant difference was found in the measurements between Lv-shRNA-NC group and the blank control group (P>0.05).</p><p><b>CONCLUSION</b>E2F-1 gene silencing can enhance cisplatin chemosensitivity of gastric cancer SGC-7901/DDP cells possibly by down-regulating survivin and Bcl-2 expressions, suggesting the value of E2F-1 as a new chemotherapeutic target for gastric cancer.</p>

Dynamic expression of E2F1 in lung of premature rats with hyperoxia-induced chronic lung disease and its significance / 中南大学学报(医学版)

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.

Effect of EBV immediate-early protein Zta on the cell cycle of Daudi cells and its mechanisms / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the effect of EBV immediate-early protein Zta on cell cycle of Daudi cells and the involved mechanisms.</p><p><b>METHODS</b>The expression vector encoding Zta was constructed and electroporated into Daudi cells. Flow cytometric analysis was used to detect the cell cycle, Western blot to the protein levels of p21, Rb and E2F-1.</p><p><b>RESULTS</b>The vector was constructed successfully, the expression of Zta protein inhibited the proliferation of Daudi cells and promoted cell cycle from G(0)/G(1) phase \[(30.0 ± 3.4)%\] to S phase \[(47.7 ± 1.1)%\]. Meanwhile, Rb expression was significantly downregulated, E2F-1 and p21 expression upregulated by Zta.</p><p><b>CONCLUSION</b>Zta could promote G(0)/G(1) phase to S phase transition in Daudi cells, which might be associated with the reduced expression of Rb and increased expression of E2F-1 and p21 protein.</p>

Hepatitis B virus X protein regulates the mEZH2 promoter via the E2F1-binding site in AML12 cells / 癌症

Histone lysine methyltransferase EZH2 has been reported to be frequently overexpressed in hepatocellular carcinoma (HCC) tissues and associated with hepatocarcinogenesis. However, the exact mechanism of EZH2 up-regulation in HCC has not been determined. In this study, we used murine hepatocyte AML12 cells to investigate the role of hepatitis B virus X protein (HBx) in regulating the expression of mEZH2. Western blot analysis demonstrated that the expression level of mEZH2 protein in AML12 cells was up-regulated by HBx in a dose-dependent manner. To further investigate the mechanism of mEZH2 overexpression, the 2500 bp regulatory sequence upstream from the first exon of the mEZH2 gene was amplified from AML12 genomic DNA and constructed into a luciferase reporter plasmid. The luciferase activity of the mEZH2 promoter significantly increased in AML12 cells co-transfected with HBx plasmid, and deleting the -486/-214 promoter region decreased HBx-induced mEZH2 promoter activation by nearly 50%. The -486/-214 region was then analyzed in the TRANSFAC 6.0 database and a typical E2F1-binding site was found. Mutation of this E2F1-binding site or knockdown of E2F1 expression by RNAi led to a dramatic decrease in HBx-induced activation of the mEZH2 promoter and mEZH2 overexpression in AML12 cells. These results provide evidence that HBx up-regulates mEZH2 expression by transactivating the mEZH2 promoter through E2F1 transcription factor, thereby providing new epigenetic evidence for the carcinogenic effect of HBx.

Lentivirus-mediated RNA interference targeting E2F-1 inhibits human gastric cancer MGC-803 cell growth in vivo

The E2F-1 transcription factor is post-translationally modified and stabilized in response to various forms of DNA damage to regulate the expression of cell-cycle and pro-apoptotic genes. The sustained overexpression of E2F-1 is a characteristic feature of gastric cancer. In this study, we investigated the role of short hairpin RNA (shRNA) targeting E2F-1 gene on human gastric cancer MGC-803 cell growth in vivo, and preliminarily revealed the mechanism. Thus, we constructed recombinant pGCSIL-GFP-shRNA-E2F-1 lentiviral vector to knock down E2F-1 expression in human gastric cancer MGC-803 cells in vivo, and studied the effect of E2F-1 shRNA on growth of MGC-803 tumor and evaluated its treatment efficacy. Our data demonstrated that in a mouse model of established gastric cancer, intratumor injection of lentiviral shRNA targeting E2F-1 definitely decreased the endogenous E2F-1 mRNA and protein expression in MGC-803 tumor, and inhibited tumor growth and promoted tumor cells apoptosis. Moreover, we found that E2F-1 shRNA increased the expression of phosphatase and tensin homolog (PTEN), activated caspase-3 and caspase-9, and suppressed nuclear factor (NF)-kappaB expression in tumor tissue as determined by reverse transcription (RT)-PCR and western blotting. In summary, shRNA targeting of E2F-1 can effectively inhibits human gastric cancer MGC-803 cell growth in vivo and may be a potential therapeutic strategy for gastric cancer.

Pseudomonas aeruginosa Exotoxin A Reduces Chemoresistance of Oral Squamous Carcinoma Cell via Inhibition of Heat Shock Proteins 70 (HSP70)

PURPOSE: Oral squamous carcinoma (OSCC) cells exhibit resistance to chemotherapeutic agent-mediated apoptosis in the late stage of malignancy. Increased levels of heat shock proteins 70 (HSP70) in cancer cells are known to confer resistance to apoptosis. Since recent advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers, we investigated the effect of Pseudomonas aeruginosa exotoxin A (PEA) on HSP70 expression and induction of apoptosis in chemoresistant OSCC cell line (YD-9). MATERIALS AND METHODS: The apoptotic effect of PEA on chemoresistant YD-9 cells was confirmed by MTT, Hoechst and TUNEL stains, DNA electrophoresis, and Western blot analysis. RESULTS: While YD-9 cells showed high resistance to chemotherapeutic agents such as etoposide and 5-fluorouraci (5-FU), HSP70 antisense oligonucelotides sensitized chemoresistant YD-9 cells to etoposide and 5-FU. On the other hand, PEA significantly decreased the viability of YD-9 cells by deteriorating the HSP70-relating protecting system through inhibition of HSP70 expression and inducing apoptosis in YD-9 cells. Apoptotic manifestations were evidenced by changes in nuclear morphology, generation of DNA fragmentation, and activation of caspases. While p53, p21, and E2F-1 were upregulated, cdk2 and cyclin B were downregulated by PEA treatment, suggesting that PEA caused cell cycle arrest at the G2/M checkpoint. CONCLUSION: Therefore, these results indicate that PEA reduced the chemoresistance through inhibition of HSP70 expression and also induced apoptosis in chemoresistant YD-9 cells.

ATM modulates transcription in response to histone deacetylase inhibition as part of its DNA damage response

Chromatin structure has a crucial role in a diversity of physiological processes, including development, differentiation and stress responses, via regulation of transcription, DNA replication and DNA damage repair. Histone deacetylase (HDAC) inhibitors regulate chromatin structure and activate the DNA damage checkpoint pathway involving Ataxia-telangiectasia mutated (ATM). Herein, we investigated the impact of histone acetylation/deacetylation modification on the ATM-mediated transcriptional modulation to provide a better understanding of the transcriptional function of ATM. The prototype HDAC inhibitor trichostain A (TSA) reprograms expression of the myeloid cell leukemia-1 (MCL1) and Gadd45alpha genes via the ATM-mediated signal pathway. Transcription of MCL1 and Gadd45alpha is enhanced following TSA treatment in ATM+ cells, but not in isogenic ATM- or kinase-dead ATM expressing cells, in the ATM-activated E2F1 or BRCA1-dependent manner, respectively. These findings suggest that ATM and its kinase activity are essential for the TSA-induced regulation of gene expression. In summary, ATM controls the transcriptional upregulation of MCL1 and Gadd45alpha through the activation of the ATM-mediated signal pathway in response to HDAC inhibition. These findings are important in helping to design combinatory treatment schedules for anticancer radio- or chemo-therapy with HDAC inhibitors.

Expression of p14(ARF) and E2F-1 in lung cancer in Gejiu and Xuanwei regions of Yunnan Province / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>The 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).</p><p><b>CONCLUSION</b>There 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.</p>

The Expressions of E2F1 and p53 in Gastrointestinal Stromal Tumors and Their Prognostic Significance

BACKGROUND: E2F1 plays a critical role in the G1-to-S phase transition by inducing various genes that encode S phase-activating proteins and that modulate such diverse cellular functions as DNA synthesis, mitosis and apoptosis. The purpose of this study was to assess the E2F1 expression in relation to the clinicopathologic parameters and other tumor markers in gastrointestinal stromal tumors. METHODS: Immunohistochemical stainings for obtaining the E2F1, p53, and Ki-67 labeling indices were performed on a tissue microarray of 72 gastrointestinal stromal tumor specimens. The clinicopathologic parameters that were analyzed including the risk grade system by Miettinen et al. and the disease-free survival (DFS) rate. RESULTS: 1) An E2F1 expression was correlated with a larger tumor size, a p53 expression and a shorter period of DFS (p=0.014, p=0.007, and p=0.039). 2) A p53 expression was significantly associated with a high risk grade, a larger tumor size, high mitotic counts and a shorter period of DFS (p=0.003, p=0.044, p<0.001, and p<0.0001). 3) A high-risk grade and the epithelioid type were significantly associated with a shorter period of DFS (p=0.0006 and p=0.0008). CONCLUSIONS: E2F1, as well as p53, may be a potentially novel independent prognostic factor for predicting a worse outcome for those patients suffering with Gastrointestinal stromal tumors.

The effect of p21 on transcription of survivin in hepatocellular carcinoma HepG2 cells and its regulation mechanism / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To observe the inhibitory effect of cyclin-dependent kinase inhibitor p21 on regulation of survivin transcription in human liver cancer HepG cells, and explore the related mechanisms.</p><p><b>METHODS</b>Doxorubicin (DOX) was used to treat HepG cells. Eukaryotic vector pEGFP-C2-p21 was transfected into HepG cells by lipofectamine and positive clones were screened out by G418. The mRNA expression of p21, p53 and survivin were detected by real-time fluorescent quantitative polymerase chain reaction (RQ-PCR). Flow cytometry was used to determine the cell cycle phases, and reverse transcription polymerase chain reaction (RT-PCR) was used to measure the levels of E2F-1 or p300.</p><p><b>RESULTS</b>After treatment with DOX, the expression of p53 and p21 was increased, whereas that of survivin was reduced during 24 hours of the treatment. After transfection the p21 level was 2100.1-fold or 980.9-fold enhanced in comparison with that in HepG2 cells or HepG2-pEGFP cells. Survivin level was markedly down-regulated to 0.5% or 0.6% relative to that in the other two groups, nevertheless, significant p53 changes were not observed. Overexpression of p21 resulted in G1/G0 phase arrest (F = 31.59, P < 0.01), meanwhile, E2F-1 mRNA or p300 mRNA were less expressed compared with that in the other controls (F(E2F-1) = 125.28, P < 0.05; Fp300 = 46.01, P < 0.01).</p><p><b>CONCLUSION</b>p21 could be a potential mediator of survivin suppression at transcription level in HepG2 cells, which might be through the block at G1/G0 phase and down-regulation of transcription factors E2F-1 and p300.</p>

Effects of p53 in benzo (a) pyrene induced p21 and E2F-1 expression and cell cycle changes / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the roles of p53 in cell cycle changes on human embryo lung fibroblasts (HELF) induced by benzo(a) pyrene[ B(a) P], and relationships between p53 and p21, E2F-1.</p><p><b>METHODS</b>Cells transfected with p53 siRNA plasmid (p53-H) and CMV vector (HELF/CMV) were cultured with serum-free R/MINI-1640 for 48 hours, then treated with 2 micromol/L B(a)P for 24 hours. Flow cytometry assay was used for detecting the cell cycle alteration after being exposed to B(a)P. Changes of p53 and p21 expressions were checked using Western blot assay, and the cytoplasmic and nuclear extraction was used to observe the subcellular localizations of p53 and p21. The immunofluorescence assay was used to check changes of E2F-1 expression and the distribution of E2F-1 in nuclear and cytoplasm after exposed to B (a)P. p53siRNA plasmid and the chemical inhibitor of p53 [pifithrin-alpha (PFT)] were used to observe effects of p53 in B(a)P induced cell cycle changes and the relationships of p53 and p21, E2F-1.</p><p><b>RESULTS</b>After 2 micromol/L B(a)P exposure, the ratio of G1 phase cells (71 +/- 5)% was decreased to (39 +/- 4)% (P < 0.05). p53, p21 and E2F-1 expressions were increased significantly, and over expressed proteins were mostly located in nuclear after B(a)P treatment. When p53 expression was inhibited by p53 siRNA or PFT, the decreases of G1 phase in response to B(a)P treatment still existed, and over expression of p21 induced by B(a)P was attenuated, especially in nuclear, but E2F-1 over expression was not changed significantly.</p><p><b>CONCLUSION</b>B(a)P could induce cell cycle changes through p53 independent pathways. And p53 could regulate p21 expression positively, but not E2F-1.</p>

Molecular regulation of KIR3DL1 gene expression by transcription factor E2F1 / 中华血液学杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>E2F1 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.</p>