Induction of Apoptosis by Isoalantolactone in Human Hepatocellular Carcinoma Hep3B Cells through Activation of the ROS-Dependent JNK Signaling Pathway.

Min Yeong Kim,Cheol Park,So Young Kim,Seon Yeong Ji,Hyun Hwangbo,Hyesook Lee,Sun-Hee Leem,Gi-Young Kim,Yung Hyun Choi,Su Hyun Hong,Shin-Hyung Park

doi:10.3390/pharmaceutics13101627

Min Yeong Kim, Cheol Park + Show 9 more

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https://doi.org/10.3390/pharmaceutics13101627

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Abstract

Isoalantolactone (IALT) is one of the isomeric sesquiterpene lactones isolated from the roots of Inula helenium L. IALT is known to possess various biological and pharmacological activities, but its anti-cancer mechanisms are not well understood. The aim of the present study was to investigate the anti-proliferative effects of IALT in human hepatocellular carcinoma (HCC) cells and to evaluate the potential anti-cancer mechanisms. Our results demonstrated that IALT treatment concentration-dependently suppressed the cell survival of HCC Hep3B cells, which was associated with the induction of apoptosis. IALT increased the expression of death-receptor-related proteins, activated caspases, and induced Bid truncation, subsequently leading to cleavage of poly (ADP-ribose) polymerase. In addition, IALT contributed to the cytosolic release of cytochrome c by destroying mitochondrial integrity, following an increase in the Bax/Bcl-2 expression ratio. However, IALT-mediated growth inhibition and apoptosis were significantly attenuated in the presence of a pan-caspase inhibitor, suggesting that IALT induced caspase-dependent apoptosis in Hep3B cells. Moreover, IALT activated the mitogen-activated protein kinases signaling pathway, and the anti-cancer effect of IALT was significantly diminished in the presence of a potent c-Jun N-terminal kinase (JNK) inhibitor. IALT also improved the generation of intracellular reactive oxygen species (ROS), whereas the ROS inhibitor significantly abrogated IALT-induced growth reduction, apoptosis, and JNK activation. Furthermore, ROS-dependent apoptosis was revealed as a mechanism involved in the anti-cancer activity of IALT in a 3D multicellular tumor spheroid model of Hep3B cells. Taken together, our findings indicate that IALT exhibited anti-cancer activity in HCC Hep3B cells by inducing ROS-dependent activation of the JNK signaling pathway.

Highlights

Hepatocellular carcinoma (HCC) is the most commonly diagnosed primary liver cancer that arises from hepatocytes
To investigate the effect of IALT on the proliferation of Hep3B cells, Hep3B cells were treated with various concentrations of IALT for 48 h, and cell viability was measured by the MTT assay
IALT significantly suppressed cell viability in non-liver-derived carcinoma cells, including prostate cancer, breast cancer and lung cancer cell lines (Supplementary Figure S1B). These results suggest that IALT has more potential effect on the suppression of cell proliferation of various human carcinoma, including hepatocellular carcinoma (HCC), than normal cells

Summary

Introduction

Hepatocellular carcinoma (HCC) is the most commonly diagnosed primary liver cancer that arises from hepatocytes. Infection with hepatitis B and C viruses is a major cause of the increased prevalence of HCC, consumption of contaminated food, cirrhosis related to heavy drinking, and nonalcoholic fatty liver disease act as risk factors [3,5]. These patients are usually treated with surgical resection, radiotherapy, and chemotherapy, but the recurrence rate of the tumor after treatment is still very high [3,5]. It is urgent to understand the basic mechanism of HCC development and discover safe and effective therapeutic agents with fewer side effects that can inhibit the proliferation of HCC cells

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