miR-579-3p controls hepatocellular carcinoma formation by regulating the PI3K-AKT pathway in chronically inflamed liver (miRNA expression)

Background & Aims: Chronic liver inflammation causes continuous liver damage with progressive liver fibrosis and cirrhosis, which may eventually lead to hepatocellular carcinoma (HCC). Whereas, the ten-year incidence for HCC in cirrhotic patients is approximately 20%, many cirrhotic patients remain tumor-free for their entire lives. Therefore, we wanted to clarify the mechanisms defining the different outcomes of chronic liver inflammation. Methods: We designed a longitudinal study comparing the mRNA and miRNA expression profiles in matched non-tumoral liver tissue from patients developing HCC (n = 30) versus patients remaining tumor-free (n = 27). The liver parenchyma was analyzed before and after HCC development in the same patient. Cirrhotic patients remaining tumor-free within a similar time frame served as a control cohort. mRNA expression of genes associated with cancer development and miRNAs were examined by the nCounterNanostring technology. The role of the identified genes involved in HCC development was evaluated by immunohistochemistry and in vitro assays. Results: Comparison of the two cohorts revealed that liver tissue from patients developing HCC displayed activation of NF-B, Insulin receptor and PI3K-AKT pathways, in parallel with increased hepatocyte proliferation and damage. Furthermore, downregulation of miR-579-3p was found as an early step in HCC development. MiR-579-3p directly attenuated PIK3CA expression and consequently AKT and pAKT. In vitro analyses confirmed that miR-579-3p controlled cell proliferation, migration and colony formation. Conclusions: Liver tissues from patients developing HCC revealed a more severe damage to the parenchyma with elevated hepatocyte proliferation. Moreover, miR-579-3p was identified as a potential novel tumor suppressor regulating PI3K-AKT signalling at the early stages of HCC development. In the study we analyzed miRNA expression in sequential liver biopsies from the same patient at two points in time: once when no hepatocellular carcinoma was present in the liver (1st biopsy) and once a hepatocellular tumor was present in the liver (2nd biopsy), in parallel we analyzed sequential biopsies from cirrhotic patients which remained tumor-free over a similar time free. 23 patients which developed hepatocellular carcinoma and 26 patients which remained tumor-free were included.