Methylation‑associated inactivation of JPH3 and its effect on prognosis and cell biological function in HCC.

Abstract

In recent years, researchers have found that epigenetics plays an important role in the occurrence and development of hepatocellular carcinoma (HCC). DNA methylation is involved in the proliferation and metastasis of HCC. However, the junctophilin 3 (JPH3) level and the potential regulatory mechanism of its DNA methylation in HCC remain uncertain. In the present study, 73 HCC samples were enrolled to analyze the expression of JPH3. Reverse-transcription quantitative PCR, western blotting and immunohistochemistry were used to detect the expression of JPH3 in HCC. Kaplan-Meier method and Cox regression analysis were applied to evaluate the prognostic impact of JPH3 on HCC patients. DNA methylation-specific PCR and bisulfite Sanger sequencing were used to detect the degree of DNA methylation of JPH3 in HCC. The demethylation drug 5-Aza-2′-deoxycytidine (5-Aza) was used to reduce the DNA methylation of JPH3. The role of JPH3 in the malignant biological behavior of HCC by promoting epithelial-mesenchymal transition (EMT) was confirmed by functional cell experiments. The results showed that JPH3 exhibited low levels in HCC tissues and cell lines. HCC patients with low expression of JPH3 had poor survival outcomes. JPH3 had higher DNA methylation levels in HCC tissues and cell lines. When the demethylation drug 5-Aza was used to reduce the degree of methylation of JPH3, its protein expression level was significantly increased and it significantly inhibited the malignant biological behavior of HCC cells. Additionally, effective increase in the expression of JPH3 through gene regulation technology also inhibited the proliferation, invasion and migration of HCC cells. After altering the DNA methylation level of JPH3, the EMT of HCC cells was also affected. Therefore, our study demonstrated the inactivation of JPH3 by promoter methylation and its function as a tumor suppressor in HCC. JPH3 may serve as a biomarker for early diagnosis and as a potential therapeutic target for HCC.