Thymoquinone potentiates miR-16 and miR-375 expressions in hepatocellular carcinoma.

Aims: MicroRNAs (miRNAs) are non-coding RNAs that control post-transcriptional gene expression. Recently, miRNAs were confirmed to be promising biomarkers for different pathological conditions. This study assessed the role of serum miR-16 and miR-375 in HCC development in chronic liver disease patients such as cirrhosis. Moreover, miR-16 and miR-375 levels were estimated in HCC cell lines (HepG2 and Huh7) after treatment with doxorubicin (DOX), thymoquinone (TQ) and their combination.

Main Methods: Serum miR-16 and miR-375 were analyzed in 30 HCC patients, 20 cirrhosis patients and 10 healthy volunteers using RT-PCR. Moreover, HepG2 and Huh7 cells were incubated with DOX, TQ or TQ/DOX combination for 24 h and the levels of miR-16, miR-375 and gene expression of anti-apoptotic protein BCL-2 were determined in cell lysates using RT- PCR. Moreover, the ability of DOX, TQ and TQ/DOX combination to induce apoptosis were analyzed by measuring caspase-3 expression using ELISA method.

Key Findings: Serum miR-16 and miR-375 levels were significantly decreased in HCC patients as compared to cirrhosis and healthy control group. Also, combined use of serum miR-16 and miR-375 showed a better predictive ability than each alone. Moreover, the expression level of miR-16 and miR-375 in HepG2 and Huh7 cells increased significantly after treatment with DOX and TQ. Also, TQ/DOX combination improved apoptosis by increasing caspase-3 expression and decreasing of BCL-2 expression.

Significance: This study proved that the combined use of serum miR-16 and miR-375 was better than each alone for HCC detection. Moreover, TQ induced apoptosis and upregulatedmiR-16 and miR-375 expression in HCC cells that may explain its anticancer activity.