Quantitative RT-PCR demonstrated a gradual ascension of miR-155 expression in cirrhotic liver tissues and in HCC tumor tissues compared with low expression levels in normal liver tissues.
We found that microRNA-155 expression levels were high in tumor tissues in patients with post-OLT HCC recurrence (n = 45) compared with those in patients with non-recurrence (n = 55) (P = 0.001) and correlated with micro-vascular invasion of HCC tissue samples (P = 0.001).
Intriguingly, all these normalization strategies indicated that circulating miRNA-155 is greatly upregulated in patients with HCC and GC, but downregulated in benign hepatic disease.
Comparing miRNA fold changes in the HCC group vs the non HCC groups, there was significant fold decrease in miR-126 (P= 0.034), miR-129 (P= 0.006), miR-155 (P= 0.011), miR-203 (<0.001) and miR-223 (P= 0.013).
Calculated expression of miRNA155 revealed that relative quantity (RQ) miR 155 was overexpressed in sera of HCC patients when compared to patients with liver cirrhosis and controls (p <0.0001).
Further, the overexpression of miR-155 in HCC cell line Huh-7 led to increased levels of cell invasion and migration compared with untreated control Huh-7 cells.
JPX and XIST expression was significantly decreased in HCC pathologic specimens, compared to adjacent tissue, which correlated with HCC progression and increased miR-155-5p expression.
These results suggest that exosomes derived from HCC cells under hypoxia induce tube formation of HUVECs and that exosomal miR-155 may affect angiogenic activity in HCC.