AIM:To clarify the specific roles and mechanisms of long interspersed nuclear element-1 ORF-1 protein [human long interspersed nuclear element-1(LINE-1),ORF-1p] in chemotherapeutic drug resistance and cell proliferati...AIM:To clarify the specific roles and mechanisms of long interspersed nuclear element-1 ORF-1 protein [human long interspersed nuclear element-1(LINE-1),ORF-1p] in chemotherapeutic drug resistance and cell proliferation regulation in hepatocellular carcinoma(HCC) cells.METHODS:MTT assays were performed to identify the effect of the chemotherapeutic drug toxicity on HepG2 cells.Cell proliferation inhibition and the IC 50 were calculated by the Origin 8.0 software.Western blotting assays were performed to investigate whether LINE-1 ORF-1p modulates the expression of some important genes,including p53,p27,p15,Bcl-2,mdr,and p-gp.To corroborate the proliferation and anchor-independent growth results,the HepG2 cells were analyzed by flow cytometry to investigate the effect of LINE-1 ORF1p on the apoptosis regulation.RESULTS:LINE-1 ORF-1p contributed to the resistance to several chemotherapeutic drugs(cisplatin and epirubicin) in HepG2 cells.The IC 50 of the epirubicin and cisplatin increased from 36.04 nmol/L to 59.11 nmol/L or from 37.94 nmol/L to 119.32 nmol/L.Repression of LINE-1 ORF-1p expression by the siRNA could markedly enhance the response of HepG2 cells to the epirubicin and cisplatin.The IC 50 correspondingly decreased from 28.06 nmol/L to 3.83 nmol/L or from 32.04 nmol/L to 2.89 nmol/L.Interestingly,down-regulation of LINE-1 ORF-1p level by siRNA could promote the response of HepG2 cells to the paclitaxel.The IC 50 decreased from 35.90 nmol/L to 7.36 nmol/L.However,overexpression of LINE-1 ORF-1p did not modulate the paclitaxel toxicity in HepG2 cells.Further Western blotting revealed that LINE-1 ORF-1p enhanced mdr and p-gp gene expression.As a protein arrested in the nucleus,LINE-1 ORF-1p may function through modulating transcriptional activity of some important transcription factors.Indeed,LINE-1 ORF-1p promoted HepG2 cell proliferation,anchor-independent growth and protected the cells against apoptosis through modulating the expression of p15,p21,p53,and Bcl-2 genes.CONCLUSION:LINE-1 ORF-1p promotes HepG2 cell proliferation and plays an important role in the resistance of chemotherapeutic drugs.By establishing novel roles and defining the mechanisms of LINE-1 ORF1p in HCC chemotherapeutic drug resistance and cell proliferation regulation,this study indicates that LINE-1 ORF-1p is a potential target for overcoming HCC chemotherapeutic resistance.展开更多
Background： DNA hypomethylation of long interspersed nuclear elements- 1 （LINEs- 1 ） occurs during carcinogenesis, whereas intbmaation addressing LINE-1 methylation in Wilms tumor （WT） is limited. The main purpos...Background： DNA hypomethylation of long interspersed nuclear elements- 1 （LINEs- 1 ） occurs during carcinogenesis, whereas intbmaation addressing LINE-1 methylation in Wilms tumor （WT） is limited. The main purpose of our study was to quantity, LINE-1 methylation levels and evaluate their relationship with relative telomere length （TL） in WT. Methods： We investigated LINE-1 methylation and relative TL using bisulfite-polymerase chain reaction （PCR） pyrosequencing and quantitative PCR, respectively, in 20 WT tissues, 10 normal kidney tissues and a WT cell line. Significant changes were analyzed by t-tests. Results： LINE-1 methylation levels were significantly lower （P 〈 0.05） and relative TLs were sigmificantly shorter （P 〈 0.05） in WT compared with normal kidney. There was a significant positive relationship between LINE- 1 methylation and relative TL in WT （r = 0.671, P = 0.001 ）. LINE- 1 Methylation levels were significantly associated with global DNA methylation （r = 0.332, P 〈 0.01 ）. In addition, relative TL was shortened and LINE- 1 methylation was decreased in a WT cell line treated with the hypomethylating agent 5-aza-2＇-deoxycytidine compared with untreated WT cell line. Conclusion： These results suggest that LINE-1 hypomethylation is common and may be linked to telomere shortening in WT.展开更多
AIM:To determine global DNA methylation in paired hepatocellular carcinoma(HCC) samples using several different assays and explore the correlations between hypomethylation and clinical parameters and biomarkers,includ...AIM:To determine global DNA methylation in paired hepatocellular carcinoma(HCC) samples using several different assays and explore the correlations between hypomethylation and clinical parameters and biomarkers,including that of aflatoxin B 1 exposure.METHODS:Using the radio labeled methyl acceptance assay as a measure of global hypomethylation,as well as two repetitive elements,including satellite 2(Sat2) by MethyLight and long interspersed nucleotide elements(LINE1),by pyrosequencing.RESULTS:By all three assays,mean methylation levels in tumor tissues were significantly lower than that in adjacent tissues.Methyl acceptance assay log(mean ± SD) disintegrations/min/ng DNA are 70.0 ± 54.8 and 32.4 ± 15.6,respectively,P = 0.040;percent methylation of Sat2 42.2 ± 55.1 and 117.9 ± 88.8,respectively,P < 0.0001 and percent methylation LINE1 48.6 ± 14.8 and 71.7 ± 1.4,respectively,P < 0.0001.Aflatoxin B 1 albumin(AFB 1-Alb) adducts,a measure of exposure to this dietary carcinogen,were inversely correlated with LINE1 methylation(r =-0.36,P = 0.034).CONCLUSION:Consistent hypomethylation in tumor compared to adjacent tissue was found by the three different methods.AFB 1 exposure is associated with DNA global hypomethylation,suggesting that chemical carcinogens may influence epigenetic changes in humans.展开更多
AIM: To investigate insulin-like growth factor 2 (IGF2) differentially methylated region (DMR)0 hypomethylation in relation to clinicopathological and molecular features in colorectal serrated lesions.
基金Supported by The Key Scientific and Technological Research Foundation of the National Special Purpose Program,No.2008ZX10002-018
文摘AIM:To clarify the specific roles and mechanisms of long interspersed nuclear element-1 ORF-1 protein [human long interspersed nuclear element-1(LINE-1),ORF-1p] in chemotherapeutic drug resistance and cell proliferation regulation in hepatocellular carcinoma(HCC) cells.METHODS:MTT assays were performed to identify the effect of the chemotherapeutic drug toxicity on HepG2 cells.Cell proliferation inhibition and the IC 50 were calculated by the Origin 8.0 software.Western blotting assays were performed to investigate whether LINE-1 ORF-1p modulates the expression of some important genes,including p53,p27,p15,Bcl-2,mdr,and p-gp.To corroborate the proliferation and anchor-independent growth results,the HepG2 cells were analyzed by flow cytometry to investigate the effect of LINE-1 ORF1p on the apoptosis regulation.RESULTS:LINE-1 ORF-1p contributed to the resistance to several chemotherapeutic drugs(cisplatin and epirubicin) in HepG2 cells.The IC 50 of the epirubicin and cisplatin increased from 36.04 nmol/L to 59.11 nmol/L or from 37.94 nmol/L to 119.32 nmol/L.Repression of LINE-1 ORF-1p expression by the siRNA could markedly enhance the response of HepG2 cells to the epirubicin and cisplatin.The IC 50 correspondingly decreased from 28.06 nmol/L to 3.83 nmol/L or from 32.04 nmol/L to 2.89 nmol/L.Interestingly,down-regulation of LINE-1 ORF-1p level by siRNA could promote the response of HepG2 cells to the paclitaxel.The IC 50 decreased from 35.90 nmol/L to 7.36 nmol/L.However,overexpression of LINE-1 ORF-1p did not modulate the paclitaxel toxicity in HepG2 cells.Further Western blotting revealed that LINE-1 ORF-1p enhanced mdr and p-gp gene expression.As a protein arrested in the nucleus,LINE-1 ORF-1p may function through modulating transcriptional activity of some important transcription factors.Indeed,LINE-1 ORF-1p promoted HepG2 cell proliferation,anchor-independent growth and protected the cells against apoptosis through modulating the expression of p15,p21,p53,and Bcl-2 genes.CONCLUSION:LINE-1 ORF-1p promotes HepG2 cell proliferation and plays an important role in the resistance of chemotherapeutic drugs.By establishing novel roles and defining the mechanisms of LINE-1 ORF1p in HCC chemotherapeutic drug resistance and cell proliferation regulation,this study indicates that LINE-1 ORF-1p is a potential target for overcoming HCC chemotherapeutic resistance.
基金National Natural Science Foundation of China （No. 81301773）.
文摘Background： DNA hypomethylation of long interspersed nuclear elements- 1 （LINEs- 1 ） occurs during carcinogenesis, whereas intbmaation addressing LINE-1 methylation in Wilms tumor （WT） is limited. The main purpose of our study was to quantity, LINE-1 methylation levels and evaluate their relationship with relative telomere length （TL） in WT. Methods： We investigated LINE-1 methylation and relative TL using bisulfite-polymerase chain reaction （PCR） pyrosequencing and quantitative PCR, respectively, in 20 WT tissues, 10 normal kidney tissues and a WT cell line. Significant changes were analyzed by t-tests. Results： LINE-1 methylation levels were significantly lower （P 〈 0.05） and relative TLs were sigmificantly shorter （P 〈 0.05） in WT compared with normal kidney. There was a significant positive relationship between LINE- 1 methylation and relative TL in WT （r = 0.671, P = 0.001 ）. LINE- 1 Methylation levels were significantly associated with global DNA methylation （r = 0.332, P 〈 0.01 ）. In addition, relative TL was shortened and LINE- 1 methylation was decreased in a WT cell line treated with the hypomethylating agent 5-aza-2＇-deoxycytidine compared with untreated WT cell line. Conclusion： These results suggest that LINE-1 hypomethylation is common and may be linked to telomere shortening in WT.
基金Supported by A grant from the National Institute of Health,No. ES005116 and No.P30ES009089
文摘AIM:To determine global DNA methylation in paired hepatocellular carcinoma(HCC) samples using several different assays and explore the correlations between hypomethylation and clinical parameters and biomarkers,including that of aflatoxin B 1 exposure.METHODS:Using the radio labeled methyl acceptance assay as a measure of global hypomethylation,as well as two repetitive elements,including satellite 2(Sat2) by MethyLight and long interspersed nucleotide elements(LINE1),by pyrosequencing.RESULTS:By all three assays,mean methylation levels in tumor tissues were significantly lower than that in adjacent tissues.Methyl acceptance assay log(mean ± SD) disintegrations/min/ng DNA are 70.0 ± 54.8 and 32.4 ± 15.6,respectively,P = 0.040;percent methylation of Sat2 42.2 ± 55.1 and 117.9 ± 88.8,respectively,P < 0.0001 and percent methylation LINE1 48.6 ± 14.8 and 71.7 ± 1.4,respectively,P < 0.0001.Aflatoxin B 1 albumin(AFB 1-Alb) adducts,a measure of exposure to this dietary carcinogen,were inversely correlated with LINE1 methylation(r =-0.36,P = 0.034).CONCLUSION:Consistent hypomethylation in tumor compared to adjacent tissue was found by the three different methods.AFB 1 exposure is associated with DNA global hypomethylation,suggesting that chemical carcinogens may influence epigenetic changes in humans.
基金Supported by The Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for Scientific Research,grant No.23790800(to Nosho K)and 23390200(to Shinomura Y)A-STEP(Adaptable and Seamless Technology Transfer Program through Targetdriven R and D)(to Nosho K)+4 种基金Daiwa Securities Health Foundation(to Nosho K)Kobayashi Foundation for Cancer Research(to Nosho K)Sagawa Foundation for Promotion of Cancer Research(to Nosho K)Suzuken Memorial Foundation(to Nosho K),and Takeda Science Foundation(to Nosho K)USA National Institute of Health,grant number R01 CA151993(to Ogino S)
文摘AIM: To investigate insulin-like growth factor 2 (IGF2) differentially methylated region (DMR)0 hypomethylation in relation to clinicopathological and molecular features in colorectal serrated lesions.
