In Vitro Anti-hepatoma Activities of Notoginsenoside R1 Through Downregulation of Tumor Promoter miR-21

Background: Notoginsenoside R1 (NG-R1) is the predominant active ingredient and a novel triterpene saponin compound extracted from the roots of Panax notoginseng. To date, to the best of our knowledge, there are no previous studies concerning the effect of NG-R1 on hepatocellular carcinoma (HCC).

Aims: To investigate the effects of NG-R1 on HCC cell growth, apoptosis, and invasion and to explore the underlying mechanisms.

Methods: Cell viability and lactate dehydrogenase (LDH) release were evaluated by cell counting kit-8 and LDH assay, respectively. Apoptosis was assessed using flow cytometry analysis and caspase-3/7 activity assay. Cell invasion was detected by Transwell invasion assay and western blot analysis of matrix metallopeptidase (MMP)-2 and MMP-9. The effects of NG-R1 on miR-21 expression and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway were examined by qRT-PCR and western blot, respectively.

Results: NG-R1 inhibited the viability, increased LDH release and caspase-3/7 activity, induced apoptosis, and suppressed invasion in HCC cells. NG-R1 reduced miR-21 expression in HCC cells. miR-21 overexpression significantly attenuated the effects of NG-R1 on the viability, LDH release, apoptosis, caspase-3/7 activity, and invasion of HCC cells. We further demonstrated that NG-R1 inhibited the activation of the PI3K/Akt pathway in HCC cells, which was abolished by miR-21 overexpression.

Conclusions: NG-R1 exerted anti-hepatoma activity through inactivation of the PI3K/Akt pathway by downregulating miR-21, contributing to further understanding of the anti-tumor activities of NG-R1 in HCC.