Plasminogen activator inhibitor 2 (PAI2) inhibits invasive potential of hepatocellular carcinoma cells in vitro via uPA- and RB/E2F1-related mechanisms
Plasminogen activator inhibitor 2 (PAI2) has been shown to be associated with invasive phenotypes and prognosis in hepatocellular carcinoma (HCC). However, its biological roles and underlying mechanisms in invasion of HCC have not been explored. The present study aimed to address the issues.
First, sub-lines in that PAI2 was stably overexpressed and silenced were established based on MHCC97H and BEL7402 cell lines, respectively. Wound-healing and transwell assays were applied to evaluate cell migration and invasion. Urokinase-type plasminogen activator (uPA) activity was measured using an ELISA kit. Real-time RT-PCR and western blotting were used to show gene expression at mRNA and protein levels. E2F1 expression in human specimens was determined by tissue microarray-based immunohistochemical staining.
The sub-lines, MHCC97H-PAI2 and BEL7402-siPAI2, were successfully established. The two sub-lines carried much lower and higher migration and invasion powers, respectively, in contrast to the controls. In MHCC97H-PAI2 sub-line, intra-medium uPA activity was significantly decreased, while RB expression was obviously elevated, compared with the controls. The BEL7402-siPAI2 sub-line presented the opposite trend. To identify the role of RB/E2F1 pathway, we transiently overexpressed E2F1 in MHCC97H-PAI2 sub-line, and largely reversed the inhibitory effects of PAI2 on cell migration and invasion, through regulating multiple matrix metalloproteinases and epithelial–mesenchymal transition. In HCC specimens, E2F1 expression was much higher in tumor than in non-tumor tissues, and was significantly related to Edmondson–Steiner grade, overall as well as tumor-free survival.
Our data suggest that PAI2 inhibits invasive potential of HCC cells via uPA- and RB/E2F1-related mechanisms.
KeywordsHepatocellular carcinoma Plasminogen activator inhibitor 2 Urokinase-type plasminogen activator RB/E2F1 Prognosis
This study was supported by the National Natural Science Foundation of China (81301845).
Compliance with ethical standards
Conflict of interest
Ye Jin, Zhi-Yong Liang, Wei-Xun Zhou and Li Zhou declare that they have no conflict of interest.
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (Institutional and National) and with the Helsinki Declaration of 1975, as revised in 2008. This study was approved by the institutional ethics committee and informed consent was obtained from all patients.
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