Long non-coding RNA CDKN2B-AS1 promotes hepatocellular carcinoma progression via E2F transcription factor 1/G protein subunit alpha Z axis

BACKGROUND A series of long non-coding RNAs(lncRNAs)have been reported to play a crucial role in cancer biology.Some previous studies report that lncRNA CDKN2B-AS1 is involved in some human malignancies.However,its role in hepatocellular carcinoma(HCC)has not been fully deciphered.AIM To decipher the role of CDKN2B-AS1 in the progression of HCC.METHODS CDKN2B-AS1 expression in HCC was detected by quantitative real-time polymerase chain reaction.The malignant phenotypes of Li-7 and SNU-182 cells were detected by the CCK-8 method,EdU method,and flow cytometry,respectively.RNA immunoprecipitation was executed to confirm the interaction between CDKN2B-AS1 and E2F transcription factor 1(E2F1).Luciferase reporter assay and chromatin immunoprecipitation were performed to verify the binding of E2F1 to the promoter of G protein subunit alpha Z(GNAZ).E2F1 and GNAZ were detected by western blot in HCC cells.RESULTS In HCC tissues,CDKN2B-AS1 was upregulated.Depletion of CDKN2B-AS1 inhibited the proliferation of HCC cells,and the depletion of CDKN2B-AS1 also induced cell cycle arrest and apoptosis.CDKN2B-AS1 could interact with E2F1.Depletion of CDKN2B-AS1 inhibited the binding of E2F1 to the GNAZ promoter region.Overexpression of E2F1 reversed the biological effects of depletion of CDKN2B-AS1 on the malignant behaviors of HCC cells.CONCLUSION CDKN2B-AS1 recruits E2F1 to facilitate GNAZ transcription to promote HCC progression.

Upregulation of miR-34c after silencing E2F transcription factor 1 inhibits paclitaxel combined with cisplatin resistance in gastric cancer cells

BACKGROUND MicroRNA 34c(miR-34c)has been reported to be associated with malignant types of cancer,however,it remains unknown whether miR-34c is involved in chemoresistance in gastric cancer(GC).AIM To investigate the effect of miR-34c and its upstream transcription factor E2F1 on paclitaxel combined with cisplatin resistance in GC cells.METHODS Paired GC tissues and adjacent normal tissues were randomly sampled from 74 GC patients.miR-34c and E2F1 were detected by real-time quantitative PCR(qPCR)and Western blot.In addition,the drug resistance of GC cells to paclitaxel and cisplatin was induced by concentration gradient increasing methods,and changes in miR-34c and E2F1 during this process were measured.Furthermore,E2F1 and miR-34c overexpression or underexpression vectors were constructed and transfected into drug-resistant GC cells.MTT was employed to test the sensitivity of cells to paclitaxel combined with cisplatin,qPCR was adopted to detect the expression of miR-34c,Western blot was applied to detect the expression levels of E2F1,drug resistance-related proteins and apoptosis-related proteins,and flow cytometry was used for the determination of cell apoptosis and cell cycle status.RESULTS E2F1 was overexpressed while miR-34c was underexpressed in GC.After inducing GC cells to be resistant to paclitaxel and cisplatin,E2F1 expression increased while miR-34c expression decreased.Both silencing E2F1 and overexpressing miR-34c could increase the sensitivity of drug-resistant GC cells to paclitaxel combined with cisplatin,promote cell apoptosis and inhibit cell proliferation.Among which,silencing E2F1 could reduce the expression of drug resistance-related proteins and apoptosis-related proteins,while over-expression of miR-34c could upregulate the expression of apoptosis-related proteins without affecting the expression of MDR-1,MRP and other drug resistance-related proteins.Rescue experiments demonstrated that inhibiting miR-34c could significantly weaken the sensitization of drug resistant cells,and Si E2F1 to paclitaxel combined with cisplatin.CONCLUSION E2F1 inhibits miR-34c to promote the proliferation of GC cells and enhance the resistance to paclitaxel combined with cisplatin,and silencing E2F1 is conducive to improving the efficacy of paclitaxel combined with cisplatin in GC cells.

MND1通过与KLF6结合形成MND1-KLF6-E2F1正反馈环加速细胞周期进程促进肺腺癌进展

背景与目的在全球范围内,肺腺癌(lung adenocarcinoma,LUAD)在肺癌患者中所占比例不断升高,肺腺癌在癌症相关死亡中所占比例很高。本研究旨在筛选出新的癌基因,为肺腺癌治疗提供潜在靶点,探究肺腺癌发生发展的机制。方法我们通过分析基因表达综合数据库(Gene Expression Omnibus,GEO)和癌症基因组图谱(The Cancer Genome Atlas,TCGA)的数据,并进行转录组筛选和生存分析,获得了一个潜在的肺腺癌风险生物标志物——减数分裂核分裂1(meiotic nuclear divisions 1,MND1)。我们通过细胞活力检测和皮下异种移植瘤模型验证MND1在肺腺癌细胞增殖和肿瘤生长中的致癌作用。通过质谱、免疫共沉淀(co-immunoprecipitation,Co-IP)和染色质免疫共沉淀(chromatin immunoprecipitation,ChIP)等实验探讨其潜在分子机制。结果通过组织芯片染色和第三方数据分析评估,MND1高表达是肺腺癌患者总生存期的独立风险因素。体内和体外试验结果表明,MND1通过加速细胞周期进程促进肺腺癌细胞增殖。Co-IP、ChIP和双荧光素酶报告基因实验结果显示,MND1竞争性地与肿瘤抑制基因KLF6(kruppel-like factor 6,KLF6)结合,从而保护E2F转录因子1(E2F transcription factor 1,E2F1)免受KLF6诱导的转录抑制。荧光素酶报告基因和ChIP分析发现,E2F1通过反馈方式与MND1启动子结合,进而激活MND1转录。结论在肺腺癌中,MND1、KLF6和E2F1形成正反馈环调控细胞周期,导致肺腺癌顺铂耐药。MND1对肿瘤恶性进展至关重要,可能是肺腺癌潜在的治疗靶点。

Identification of a novel pathway involving a GATA transcription factor in yeast and possibly in plant Zn uptake and homeostasis

To gain a better understanding of the regulation of Zn homeostasis in plants and the degree of conservation of Zn homeostasis between plants and yeast, a cDNA library from the Zn/Cd hyperaccumulating plant species, Noccaea caerulescens, was screened for its ability to restore growth under Zn limiting conditions in the yeast mutant zaplA. ZAP1 is a transcription factor that activates the Zn dependent transcription of yeast genes involved in Zn uptake, including ZRT1, the yeast high affinity Zn transporter. From this screen two members of the E2F family of transcription factors were found to activate ZRT1 expression in a Zn independent manner. The activation of ZRTI by the plant E2F proteins involves E2F- mediated activation of a yeast GATA transcription factor which in turn activates ZRT1 expression. A ZRT1 promoter region necessary for activation by E2F and GATA proteins is upstream of two zinc responsive elements previously shown to bind ZAP1 in ZRT1. This activation may not involve direct binding of E2F to the ZRT1 promoter. The expression of E2F genes in yeast does not replace function of ZAP1; instead it appears to activate a novel GATA regulatory pathway involved in Zn uptake and homeostasis that is not Zn responsive.

Meiotic nuclear divisions 1(MND1)fuels cell cycle progression by activating a KLF6/E2F1 positive feedback loop in lung adenocarcinoma

Background:Considering the increase in the proportion of lung adenocarcinoma(LUAD)cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide,we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD.Methods:The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus(GEO)datasets and The Cancer Genome Atlas(TCGA)data were combined,and a promising risk biomarker called meiotic nuclear divisions 1(MND1)was selectively acquired.Cell viability assays and subcutaneous xenograftmodelswere used to validate the oncogenic role ofMND1 in LUADcell proliferation and tumor growth.Aseries of assays,including mass spectrometry,co-immunoprecipitation(Co-IP),and chromatin immunoprecipitation(ChIP),were performed to explore the underlying mechanism.Results:MND1 up-regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis.In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle.The results of the Co-IP,ChIP and dual-luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel-like factor 6(KLF6),and thereby protecting E2F transcription factor 1(E2F1)from KLF6-induced transcriptional repression.Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner.Conclusions:MND1,KLF6,and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD.MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.

TGF-β1-regulated miR-3691-3p targets E2F3 and PRDM1 to inhibit prostate cancer progression

Transforming growth factor-β1(TGF-β1)acts as a tumor promoter in advanced prostate cancer(PCa).We speculated that microRNAs(miRNAs)that are inhibited by TGF-β1 might exert anti-tumor effects.To assess this,we identified several miRNAs downregulated by TGF-β1 in PCa cell lines and selected miR-3691-3p for detailed analysis as a candidate anti-oncogene miRNA.miR-3691-3p was expressed at significantly lower levels in human PCa tissue compared with paired benign prostatic hyperplasia tissue,and its expression level correlated inversely with aggressive clinical pathological features.Overexpression of miR-3691-3p in PCa cell lines inhibited proliferation,migration,and invasion,and promoted apoptosis.The miR-3691-3p target genes E2F transcription factor 3(E2F3)and PR domain containing 1,with ZNF domain(PRDM1)were upregulated in miR-3691-3p-overexpressing PCa cells,and silencing of E2F3 or PRDM1 suppressed PCa cell proliferation,migration,and invasion.Treatment of mice bearing PCa xenografts with a miR-3691-3p agomir inhibited tumor growth and promoted tumor cell apoptosis.Consistent with the negative regulation of E2F3 and PRDM1 by miR-3691-3p,both proteins were overexpressed in clinical PCa specimens compared with noncancerous prostate tissue.Our results indicate that TGF-β1-regulated miR-3691-3p acts as an anti-oncogene in PCa by downregulating E2F3 and PRDM1.These results provide novel insights into the mechanisms by which TGF-β1 contributes to the progression of PCa.

E2F4 regulates the cell cycle and DNA replication in the silkworm,Bombyx mori

The E2F family of transcription factors is crucial for cell cycle progression and cell fate decisions.Although E2Fs have been widely studied in mammals,there have been few studies performed in insects.Here,we determined the function of E2F4 in the silkworm,Bombyx mori.We demonstrate that E2F proteins are highly conserved among species from lower animals to higher mammals.Overexpression of the BmE2F4 gene led to cell cycle arrest in the G1 phase,whereas interfering with the BmE2F4 mRNA led to accumulation of cells in the S phase.These results indicate that BmE2F4 is important in cell cycle regulation.We also demonstrate that the BmE2F4 gene is involved in DNA replication of BmN-SWU1 cells and DNA synthesis in the silk gland.Furthermore,we identified a protein called Bm14-3-3ζthat can interact with BmE2F4 and allow it to localize in the nucleus.Overexpression of the Bm14-3-3ζgene led to cell cycle arrest in the G1 phase,while knocking down the gene increased the proportion of cells in S phase.These findings provide important insights into the function of E2F transcription factors and increase our understanding of their involvement in cell cycle regulation.

A Combined Computational and Experimental Study on the Structure-Regulation Relationships of Putative Mammalian DNA Replication Initiator GINS

GINS, a heterotetramer of SLD5, PSF1, PSF2, and PSF3 proteins, is an emerging chromatin factor recognized to be involved in the initiation and elongation step of DNA replication. Although the yeast and Xenopus GINS genes are well documented, their orthologous genes in higher eukaryotes are not fully characterized. In this study, we report the genomic structure and transcriptional regulation of mammalian GINS genes. Serum stimulation increased the GINS mRNA levels in human cells. Reporter gene assay using putative GINS promoter sequences revealed that the expression of mammalian GINS is regulated by 17β-Estradiolstimulated estrogen receptor a, and human PSF3 acts as a gene responsive to transcription factor E2F1. The goal of this study is to present the current data so as to encourage further work in the field of GINS gene regulation and functions in mammalian cells.