Transcriptomic Analysis Of Folic Acid-treated Cells And Studies Of Folic Acid Intervention In Prevention Of Hepatocellular Carcinoma

HCC is one of the most common malignant cancer,and it has high occurrence and death rate.The accurrancy clinical diagnosis is in late stage.So the early prevention was very impotant.The studies showed that epigenetic modification played an important role on hepatocellular carcinogenesis.However,folic acid could modulate genes expression through epigenetic modification as methy-donor.Relationship between folic acid supplementation and tumor initiation was controversial,it deserves our further study on whether folic acid has chemopreventive effect on hepatocarcinogenesis.In our study,we first examined the effect of different concentrations of folic acid on human normal liver cells cultured for six months.On the condition that folic acid deficiency promoted cell proliferation,cell transformation from static to cell division,cell migration and invision.Our studies elucidated that folic acid deficiency promoted cells from normal state to malignant transformation once again.However,it's not clear how folic acid modulate the genes behind the above phenomenon.So we selected RNA-Seq to help.We finally got the target gene LCN2 by RNA-Seq technology from human normal liver cells QSG-7701,which were cultured by three different concentrations of folic acid for 6 months.The oncogene LCN2 promoted cell proliferation,cell cycle progression arrest and tumor formation.However,cells cultured with high folic acid could dramatically inhibited the expression of LCN2,and inhibited tumor formation.And cells with LCN2 knockdown in no folic acid group,could inhibit cell proliferation.In animal models,tumor formation rate of the nude mice injected with cells treated by high folic acid was the lowest in three mice groups.And nude mice injected with cells cultured by high folic acid with stable transfection of pcDNA3.1-LCN2 had the similar effect as mice injected with cells cultured without folic acid.Last,Chromatin immunoprecipitation showed that histone H3 lysine 9 di-methylation(H3K9Me2),an epigenetic mark associated with transcriptional repression,was the highest abundant in the promoter region of LCN2 in cells cultured with high folic acid.In HCC patients,LCN2 expression was higher in tumors than adjacent tissues,and folic acid levels was lower in tumors than adjacent tissues.We suspect that folic acid deficiency promoted hepatocellular carcinogenesis.In conclusion,our study demonstrates that folic acid supplementation has the chemopreventive effect on hepatocarcinogenesis.This protective effect of folic acid due to its ability to inhibit the expression of the oncogene LCN2 by regulation of histone methylation.We expect that our study will provide a better service for the clinical,and reduce the incidence of HCC.