Apoptotic effects of rhein through the mitochondrial pathways, two death receptor pathways, and reducing autophagy in human liver L02 cells

Abstract

Rhein (4,5‐dihydroxyanthraquinone‐2‐carboxylic acid) is a major component of many medicinal herbs such as Rheum palmatum L. and Polygonum multiflorum. Despite being widely used, intoxication cases associated with rhein‐containing herbs are often reported. Currently, there are no available reports addressing the effects of rhein on apoptosis in human liver L02 cells. Thus, the aim of this study is to determine the cytotoxic effects and the underlying mechanism of rhein on human normal liver L02 cells. In the present study, the methyl thiazolyl tetrazolium assay demonstrated that rhein decreased the viability of L02 cells in dose‐dependent and time‐dependent ways. Rhein was found to trigger apoptosis in L02 cells as shown by Annexin V‐fluoresceine isothiocyanate (FITC) apoptosis detection kit and cell mitochondrial membrane potential (MMP) assay, with nuclear morphological changes demonstrated by Hoechst 33258 staining. Detection of intracellular superoxide dismutase activity, lipid oxidation (malondialdehyde) content, and reactive oxygen species (ROS) levels showed that apoptosis was associated with oxidative stress. Moreover, it was observed that the mechanism implicated in rhein‐induced apoptosis was presumably via the death receptor pathway and the mitochondrial pathway, as illustrated by upregulation of TNF‐α, TNFR1, TRADD, and cleaved caspase‐3, and downregulation of procaspase‐8, and it is suggested that rhein may increase hepatocyte apoptosis by activating the increase of TNF‐α level. Meanwhile, rhein upregulates the expression of Bax and downregulates the expression of procaspase‐9 and ‐3, and it is suggested that the mitochondrial pathway is activated and rhein‐induced apoptosis may be involved. In addition, we also want to explore whether rhein‐induced apoptosis is related to the autophagic changes induced by rhein. The results showed that rhein treatment increased P62 and decreased LC3‐II and beclin‐1, which means that autophagy was weakened. The results of our studies indicated that rhein induced caspase‐dependent apoptosis via both the Fas death pathway and the mitochondrial pathway by generating ROS, and meanwhile the autophagy tended to weaken.

miR-155-5p increases the sensitivity of liver cancer cells to adriamycin by regulating ATG5-mediated autophagy

“…In addition, ATG5 could promote proliferation and metastasis and inhibit breast cancer cell apoptosis [49]. A previous study found that rhein inhibited the autophagy of human cancer cells via downregulation of ATG5 [50]. Additionally, Ra EA et al indicated that TRIM31 could promote Atg5/Atg7-independent autophagy in intestinal cells [51].…”

Hydromethanolic root and aerial part extracts from Echium arenarium Guss suppress proliferation and induce apoptosis of multiple myeloma cells through mitochondrial pathway

“…No studies in the broader literature have carried out on E. arenarium Guss plant extract or other species of the genus at this level of investigation. Many plants extracts have been described in the literature as having anti‐cancer properties and which inhibit cell proliferation by inducing the process of apoptosis in different ways depending on the nature of the products and on the kind of tumor cells 34 …”

Induction of Apoptosis by Metabolites of Rhei Radix et Rhizoma (Da Huang): A Review of the Potential Mechanism in Hepatocellular Carcinoma

“…Specifically, rhein increased ROS, tumor necrosis factor-α (TNF-α), tumor necrosis factor receptor (TNFR), and TRADD, cleaved caspase-3, and reduced MMP and pro-caspase-9 and -3. Notably, the decrease in the levels of the autophagy-related proteins LC3-II and Beclin-1 and increase in the expression of P62 indicated that rhein promoted apoptosis of L02 cells by inhibiting autophagy and decreasing their self-scavenging ability ( Li et al, 2019 ).…”