Study On The Biomolecular Network Of Genomic Copy Number Variation And Drug Response In Human Hepatocellular Carcinom

As one of the cancers with the highest mortality rate in China and the world,liver cancer has attracted extensive attention from researchers in the 21st century.Hepatocellular carcinoma(HCC)is the most common primary liver cancer.Its occurrence and development result from the complex interaction between many genetic and non-genetic factors.These factors will cause genetic and epigenetic carcinogenic changes in liver cells,induce various biological abnormalities of liver cells,and then lead to malignant transformation of adverse nodules in patients,and eventually even make tumors progress to advanced stages under evolutionary pressure selection.The pathological process in this process is extremely complex,so it still needs a lot of efforts to overcome the end point of liver cancer.With the development of sequencing technology,scientists are paying more and more attention to the relationship between genome variation and disease.As a submicroscopic genomic structural variation,copy number variation is closely related to the evolution of organisms and the occurrence of many complex diseases.In cancer,copy number variation is associated with different molecular,immunological and clinical characteristics,and is a key factor in the genetic variation of tumors.Through reviewing a large number of literatures,this study found that genomic variation in hepatocellular carcinoma may affect the chemotherapy effect and prognosis of patients with hepatocellular carcinoma.However,how copy number variation in hepatocellular carcinoma affects gene expression of cancer cells,response to chemotherapy drugs and prognosis remains unclear.In Chapter 3,this study first detected the copy number variation of human hepatoma cell lines HepG2 and Huh7 using optical genome mapping technology,first analyzed the function of the gene with copy number variation,and mapped the protein interaction network according to the gene corresponding to the enrichment pathway.At the same time,key genes in the core network of two cell lines were selected to analyze the relationship between copy number variation,gene expression and clinical survival of patients with hepatocellular carcinoma combined with RNA-seq assay and GEPIA database.The results showed that the copy number variation of HepG2 and Huh7 genomes differed greatly in the number of variants and chromosome distribution,among which the copy number,expression level and clinical prognosis of the copy number variant genes such as SRC and MAP3K7 showed cell specificity.The results not only supported the key role of SRC and MAP3K7 in hepatocellular carcinoma research.It also suggests that hepatocellular carcinoma is highly heterogeneous,and the heterogeneity of hepatocellular carcinoma may affect the occurrence,development,evolution of tumor cells and the clinical therapeutic effect of patients.The variation of HepG2 and Huh7 genomes may affect the sensitivity of cancer cells to chemotherapy drugs.Chapter 4 further explores the relationship between the heterogeneity of hepatocellular carcinoma and sensitivity to chemotherapy drugs.In this study,HepG2 and Huh7 cells were treated with different concentrations of cisplatin for 12h.The toxicity of cisplatin was detected by CCK8,the damage and senescence of cells were observed by immunofluorescence,mRNA levels were detected by RNA-seq,and the functional and concentration dependent trends of differentially expressed genes in the two cells were analyzed.The results showed that their cell vitality,cell aging damage,gene expression trend,and response were both consistent and different.With the increase of cisplatin concentration,the cell vitality of both kinds of cells decreased,while the cell damage and senescence increased.At the transcriptome level,with the increase of cisplatin concentration,DNA damage repair of the two types of cells increased,and gene expression showed dynamic changes,and the trend of gene expression was also related to the variation of cell copy number.Gene function analysis showed that epigenetic modification was inhibited,while energy and substance metabolism were significantly increased,reflecting the consistent response of HCC cells to cisplatin.Huh7 may be more sensitive to cisplatin when the concentration of cisplatin is the highest,and the expression of genes corresponding to metabolic,energy and material supply pathways of cells is significantly decreased.The results of this study reflect the specificity of hepatocellular carcinoma cell lines,which is also consistent with the high heterogeneity of clinical hepatocellular carcinoma.Such heterogeneity may be related to cisplatin resistance and poor prognosis of clinical hepatocellular carcinoma patients.In summary,through the gene expression profile analysis of copy number variation and cisplatin response in hepatocellular carcinoma,this study found that copy number variation was significantly correlated with gene expression and clinical prognosis,and also revealed the important influence of copy number variation on the development and heterogeneity of hepatocellular carcinoma.The difference in the gene expression response of the two cells to the chemotherapy drug cisplatin also enables us to understand the biological process of hepatocellular carcinoma response to cisplatin at the molecular level.However,whether the differences in cellular responses of HepG2 and Huh7 are related to genomic copy number variation,and whether copy number variation can affect cisplatin resistance in hepatocellular carcinoma patients,remains to be further studied.