Diosmetin inhibits cell proliferation and induces apoptosis by regulating autophagy via the mammalian target of rapamycin pathway in hepatocellular carcinoma HepG2 cells

Abstract

Hepatocellular carcinoma (HCC), which is a type of malignant tumor, is the fifth most common cancer in men and ninth in women worldwide. The aim of the present study was to investigate the antitumor effect of diosmetin (DIOS) in hepatocellular carcinoma HepG2 cells. The proliferation, apoptosis and autophagy rates of HepG2 cells were measured following treatment with DIOS. The effects of DIOS treatment on HepG2 cell proliferation and apoptosis rates were analyzed using MTT assays and Annexin V staining, respectively. The effect of DIOS treatment on autophagy levels was assessed using transmission electron microscopy, green fluorescent protein (GFP)-microtubule-associated protein 1 light chain (LC3) transfection and LysoTracker Red staining. Furthermore, bafilomycin A1 (BA1), an autophagy inhibitor, was used to assess the association between DIOS and cell autophagy, proliferation and apoptosis. In addition, the expression of autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase, P70S6K, phosphoinositide-dependent kinase-1, extracellular signal-regulated kinase, 5′-AMP-activated protein kinase and Akt] and apoptosis-related proteins [B-cell lymphoma (Bcl)-2-associated X protein, Bak, p53, Bcl-2 and caspase-3] were analyzed by western blotting. The results revealed that DIOS significantly inhibited proliferation (P<0.01) and induced apoptosis (P<0.001) in HepG2 cells. It was also demonstrated that DIOS triggered autophagy by regulating the mTOR pathway in HepG2 cells. Notably, following treatment of HepG2 cells with the autophagy inhibitor, BA1, the expression of apoptosis-related proteins, including Bax, Bak and p53, were significantly decreased (P<0.05), and cell viability was recovered to a certain extent. In conclusion, DIOS inhibits cell proliferation and induces apoptosis in HepG2 cells via regulation of the mTOR pathway. Thus, the results of the current study indicate that DIOS may present a potential therapeutic agent for HCC treatment.

Citrus Flavones: An Update on Sources, Biological Functions, and Health Promoting Properties

“…In addition to the increase of p53 protein expression, diosmetin reduces NF-kB activity through the decrease of the expression of Notch3 receptor, a protein highly expressed in tumors [139]. Moreover, the mammalian target of rapamycin (mTOR) pathway seems to be also negatively influenced by diosmetin and this leads to an increase of autophagosomes formation, strictly correlated with an increase of apoptosis and decrease of cell survival rate [140]. Another pathway negatively influenced by diosmetin is BMP (bone morphogenetic proteins) dependent signaling that causes p21 protein upregulation [135].…”

Autophagy suppresses proliferation of HepG2 cells via inhibiting glypican-3/wnt/&beta;-catenin signaling

“… 8 – 10 Induction of autophagy by diosmetin inhibited proliferation of HCC cells and promoted its apoptosis and could be reversed by exposure to autophagy inhibitor, bafilomycin A1. 11 …”

Inhibition of TGF-β Signaling in Gliomas by the Flavonoid Diosmetin Isolated from Dracocephalum peregrinum L.

“…The median survival is generally less than 1 year from the time of diagnosis, and even under the most favorable situations, most patients die within 2 years [7]. Diosmetin has been previously demonstrated to induce cell apoptosis and act as an anticancer compound in several cancers [23][24][25][26]. However, the effects of diosmetin on glioma have not been elucidated, and whether diosmetin can affect glioma development and the underlying mechanisms remains unknown.…”