The mechanism of DNA methylation-regulated oncogene SERPINE2 in hepatocellular carcinoma metastasis

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death. Early HCC is mainly resected by surgery, but some patients have recurrence and metastasis within 5 years after surgery. Therefore, it is essential to explore the mechanism of liver cancer metastasis and find potential intervention methods for liver cancer. DNA methylation is a form of chemical modification of DNA that can alter genetic performance without changing the DNA sequence. A large number of studies have shown that DNA methylation is an important cause of the occurrence and development of liver cancer. SERPINE2, known as PN-1, is a secreted protein with anti-serine protease activity against serine proteases such as thrombin, urokinase, and plasminogen. Previous studies have shown that alterations in SERPINE2 expression contribute to tumorigenesis and participate in tumor metastasis.

The differential expression of SERPINE2 between cancer tissues and normal tissues was analyzed using TCGA database. The correlation between SERPINE2 and clinical data was also analyzed by TCGA database. SERPINE2-knockdown and SERPINE2-overexpression HCC cell lines were constructed using lentiviruses and using transwell assay and wound healing assay to investigate the effect of SERPINE2 on HCC metastasis. Mouse model of lung colonization was established by tail vein injection of lentivirus-stabilized SERPINE2-overexpressing HCC cells.

Firstly, we found that DNA methylation of SERPINE2 is regulated by DNMT1, and the methylation level of SERPINE2 was significantly inhibited and the expression of SERPINE2 was up-regulated after AZA treatment in HCC cell lines. SERPINE2 is highly expressed in HCC and closely associated with prognosis and other clinical features of HCC, patients with high SERPINE2 expression tend to have poor prognosis, and we found that the expression level of SERPINE2 was closely related to tumor stage, the worse the tumor stage and the higher the degree of malignancy, the higher the expression level of SERPINE2. Notably, in patients with microvascular metastasis, those with high SERPINE2 expression tended to have a worse prognosis. Overexpression of SERPINE2 promotes HCC cell metastasis in vitro and in vivo. Furthermore, SERPINE2 also affects tumor cell adhesion and extracellular matrix remodeling.

In conclusion, our study has demonstrated that SERPINE2 expression is regulated by DNA methylation, and its expression is significantly higher in HCC tissues than in normal tissues, and alterations of SERPINE2 expression can significantly affect tumor cell migration, invasion, and lung colonization. In addition, we also demonstrated that SERPINE2 expression can affect cell adhesion ability and extracellular matrix remodeling. SERPINE2 is expected to be a new target for the treatment of HCC metastasis.

The authors.

This study was supported by grants from the National Natural Science Foundation of China (No. 82070652), the Key Research and Development Plan of Zhejiang Province (No. 2020C04003), Research Unit Project of the Chinese Academy of Medical Sciences (2019-I2M-5-030) and the Research Project of Jinan Microecological Biomedicine Shandong Laboratory (JNL-2022007B).

All authors have declared no conflicts of interest.