α-pinene regulates miR-221 and induces G2/M phase cell cycle arrest in human hepatocellular carcinoma cells.

Qiuxiang Xu,Jingjing Xie,Jiebo Yang,Ming Li,Fang Wang,Weiqiang Chen,Mengdie Yang,Xinshuo Lu

doi:10.1042/bsr20180980

Abstract

The naturally occurring compound α-pinene induces cell cycle arrest and antitumor activity. We examined effects of α-pinene on cell cycle regulation in hepatocellular carcinoma cells (HepG2) cells to establish a foundation for its development as a novel treatment for hepatocellular carcinoma (HCC). HepG2 cells treated with α-pinene exhibited dose-dependent growth inhibition as a result of G2/M-phase cell cycle arrest. Cell cycle arrest was associated with down-regulated cyclin-dependent kinase 1 (CDK1) and miR-221 levels and up-regulated levels of CDKN1B/p27, γ-H2AX, phosphorylated ATM, phosphorylated Chk2 and phosphorylated p53. Our observations are consistent with a model in which α-pinene inhibits miR221 expression, which leads to G2/M-phase arrest and activation of CDKN1B/p27-CDK1 and ATM-p53-Chk2 pathways that suppress human hepatoma tumor progression. Additionally, α-pinene was found to trigger oxidative stress and induce apoptosis of HepG2 cells. α-pinene, therefore, represents a potential chemotherapeutic compound for the treatment of HCC.

Highlights

The incidence of hepatocellular carcinoma (HCC), a highly malignant cancer, is increasing dramatically with annual new cases estimated at 600,000 worldwide [1,2]
We examined effects of α-pinene on cell cycle regulation in hepatocellular carcinoma cells (HepG2) cells to establish a foundation for its development as a novel treatment for hepatocellular carcinoma (HCC)
Our observations are consistent with a model in which α-pinene inhibits miR221 expression, which leads to G2/M-phase arrest and activation of CDKN1B/p27-cyclin-dependent kinase 1 (CDK1) and Ataxia Telangiectasia Mutated (ATM)-p53-Chk2 pathways that suppress human hepatoma tumor progression

Summary

Introduction

The incidence of hepatocellular carcinoma (HCC), a highly malignant cancer, is increasing dramatically with annual new cases estimated at 600,000 worldwide [1,2]. We examined whether α-pinene might act to regulate the expression of miR-221 and relevant signaling pathways impacting cell cycle dynamics in response to DNA damage involved in HCC development. Reactive oxigen species (ROS) play an important role in redox regulation during normal physiological functions but are highly reactive molecules that have the potential to cause cellular damage, including damaging DNA, RNA, and proteins and degrading essential cellular molecules [18], which will lead to cells death. We performed experiments with DCFH-DA method and Annexin V-FITC/PI to examine whether the increasing of intracellular ROS levels would lead to the apoptosis of HepG2 cells. These studies provide novel molecular insights into the biological basis of potential anticancer efficacy of α-pinene

Materials and methods

Findings

Discussion