DNA Hypermethylation Modification Promotes the Development of Hepatocellular Carcinoma by Depressing the Tumor Suppressor Gene ZNF334

Background: DNA methylation plays a pivotal role in the development and progression of tumors, but studies focused on the dynamic changes of DNA methylation in the development of hepatocellular carcinoma (HCC) are rare. This manuscript is aimed to construct pre- and early DNA methylation maps of liver cancer of the same genetic background, as well as to reveal the mechanism of epigenetics regulating gene expression during the development of liver cancer, thus providing new targets and clinical evidence for early diagnosis and shedding lights on the precise treatment for liver cancer. Methods: The study includes 5 patients who were chronic hepatitis B virus infected, clinically diagnosed as primary liver cancer and pathologically diagnosed as early liver cancer with liver dysplastic nodules. Liver fibrosis tissues, dysplastic nodules and early HCC tissues from these patients have been used to measure DNA methylation. Results: We report significant differences in the DNA methylation spectrum of three types of tissues. In the early stage of HCC, DNA hypermethylation of tumor suppressor genes is predominant. Additionally, DNA hypermethylation in the early stage of HCC changes the binding of transcription factor P53 to the promoter of tumor suppressor gene ZNF334, and inhibits the expression of ZNF334 at the transcription level. Furthermore, through a series of in vivo and in vitro experiments, we have clarified the exacerbation effect of tumor suppressor gene ZNF334 deletion in the occurrence of HCC. Combined with clinical data, we found that the overall survival and disease-free survival of patients with high ZNF334 expression are longer than the lower one. Conclusions: We constructed a sequential map of DNA methylation modification during the occurrence of HCC, and clarified the biological function and regulatory mechanism of the tumor suppressor gene ZNF334, which is regulated by related DNA methylation sites, and also provide new targets and clinical evidence for the early diagnosis and precise treatment of liver cancer.