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.

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.

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。

Oncogene goosecoid is transcriptionally regulated by E2F1 and correlates with disease progression in prostate cancer

Background:Although some well-established oncogenes are involved in cancer initiation and progression such as prostate cancer(PCa),the long tail of cancer genes remains to be defined.Goosecoid(GSC)has been implicated in cancer development.However,the comprehensive biological role of GSC in pan-cancer,specifically in PCa,remains unexplored.The aim of this study was to investigate the role of GSC in PCa development.Methods:We performed a systematic bioinformatics exploration of GSC using datasets from The Cancer Genome Atlas,Genotype-Tissue Expression,Gene Expression Omnibus,German Cancer Research Center,and our in-house cohorts.First,we evaluated the expression of GSC and its association with patient prognosis,and identified GSC-relevant genetic alterations in cancers.Further,we focused on the clinical characterization and prognostic analysis of GSC in PCa.To understand the transcriptional regulation of GSC by E2F transcription factor 1(E2F1),we performed chromatin immunoprecipitation quantitative polymerase chain reaction(qPCR).Functional experiments were conducted to validate the effect of GSC on the tumor cellular phenotype and sensitivity to trametinib.Results:GSC expression was elevated in various tumors and significantly correlated with patient prognosis.The alterations of GSC contribute to the progression of various tumors especially in PCa.Patients with PCa and high GSC expression exhibited worse progression-free survival and biochemical recurrence outcomes.Further,GSC upregulation in patients with PCa was mostly accompanied with higher Gleason score,advanced tumor stage,lymph node metastasis,and elevated prostate-specific antigen(PSA)levels.Mechanistically,the transcription factor,E2F1,stimulates GSC by binding to its promoter region.Detailed experiments further demonstrated that GSC acted as an oncogene and influenced the response of PCa cells to trametinib treatment.Conclusions:GSC was highly overexpressed and strongly correlated with patient prognosis in PCa.We found that GSC,regulated by E2F1,acted as an oncogene and impeded the therapeutic efficacy of trametinib in PCa.

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.

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.