Mingyi Li

Dihydromyricetin Reduced Bcl-2 Expression via p53 in Human Hepatoma HepG2 Cells

Dihydromyricetin (DHM) is a major active ingredient of flavonoids compounds. It exhibited anticancer activity and induced apoptosis in human hepatocellular carcinoma HepG2 cells according to our previous data. In this study, we investigated whether p53 is involved in DHM-triggered viability inhibition and apoptosis induction in cancer cells. MTT [3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay was employed to evaluate the viability of HepG2 cells after DHM treatment. Meanwhile, p53 small interfering RNA (siRNA) was adopted to silence p53 expression. Protein level of p53 and Bax/Bcl-2 were evaluated by western blot analysis. Cell counting assay showed that DHM inhibited HepG2 cell growth effectively in a time- and dose-dependent manner. P53 expression was significantly increased after DHM treatment, whereas Bcl-2 was reduced potently. Furthermore, after co-treatment with Pifithrin-α (PFT-α, p53 inhibitor), Bcl-2 expression was reversed. The expression of Bax was no significant change, which was also observed after p53 silence. These findings defined and supported a novel function that DHM could induce human hepatocellular carcinoma HepG2 cells apoptosis by up-regulating Bax/Bcl-2 expression via p53 signal pathway.

Dihydromyricetin promotes hepatocellular carcinoma regression via a p53 activation-dependent mechanism

The development of antitumor chemotherapy drugs remains a key goal for oncologists, and natural products provide a vast resource for anti-cancer drug discovery. In the current study, we found that the flavonoid dihydromyricetin (DHM) exhibited antitumor activity against liver cancer cells, including primary cells obtained from hepatocellular carcinoma (HCC) patients. In contrast, DHM was not cytotoxic to immortalized normal liver cells. Furthermore, DHM treatment resulted in the growth inhibition and remission of xenotransplanted tumors in nude mice. Our results further demonstrated that this antitumor activity was caused by the activation of the p53-dependent apoptosis pathway via p53 phosphorylation at serine (15Ser). Moreover, our results showed that DHM plays a dual role in the induction of cell death when administered in combination with cisplatin, a common clinical drug that kills primary hepatoma cells but not normal liver cells.

Resveratrol inhibits proliferation in human colorectal carcinoma cells by inducing G1/S‑phase cell cycle arrest and apoptosis through caspase/cyclin‑CDK pathways

The present study compared the effect of resveratrol on HCT116 and Caco-2 human colon cancer cells. Annexin V/propidium iodide staining, MTT assay and western blot analysis revealed that resveratrol induced cycle arrest in the two cell lines, which was evidenced by cell cycle analysis and changes in the expression of the cell cycle proteins cyclin-dependent kinase (CDK) 2, CDK4, cyclin D1, proliferating cell nuclear antigen and P21. Furthermore, resveratrol was found to have a strong apoptosis-inducing effect, which was evidenced through the high percentage of annexin V positive cells and high protein expression of cleaved-caspase-7, cleaved-caspase-9 and cleaved-poly(ADP-ribose) polymerase in the resveratrol-treated cancer cells. In conclusion, these results demonstrated that resveratrol had greater growth inhibitory and cell cycle arrest effects on Caco-2 cells than HCT116 cells, through caspase-dependent and cyclin-CDK pathways.

MicroRNA-520c-3p inhibits hepatocellular carcinoma cell proliferation and invasion through induction of cell apoptosis by targeting glypican-3

Glypican‐3 (GPC3) is a membrane‐associated heparan sulfate proteoglycan involved in regulation of cell proliferation, cell survival, cell migration and differentiation process. MicroRNAs (miRNAs) are single‐stranded, non‐coding functional RNAs that are important in many biological processes. GPC3 and miRNAs have been found to play essential roles in the development and progression of hepatocellular carcinoma (HCC). However, little information about the relationship between GPC3 and miRNAs is available nowadays. Therefore, this study aims to examine the relationship between GPC3 and miRNAs.

Dihydromyricetin induces autophagy in HepG2 cells involved in inhibition of mTOR and regulating its upstream pathways.

Dihydromyricetin (DHM), a bioactive flavonoid compound extracted from the stems and leaves of Ampelopsis grossedentata, has oxidation resistance, anti-tumor and free radical scavenging capabilities. In this study, we found that DHM-induced autophagy inhibited the cell proliferation in HepG2 cells. The transmission electron microscopy results showed that DHM induced significantly autophagosome characteristics like autophagolysosome containing degraded cellular content. GFP labled LC3 plasma transfection showed that LC3 largely diffused to punctate structures with DHM treatment, while lysosomal-rich/acidic compartments detected using LysoTracker Red staining. In addition, DHM promoted the expressions of LC3-II and Beclin-1 in a dose- and time-dependent manner. Further study showed that DHM suppressed the activation of mTOR (mammalian targets of rapamycin) involved in regulating its upstream signaling pathways including extracellular signal-regulated kinase 1/2 (ERK1/2), AMPK (AMP-activated kinase) and class III phosphatidylinositol 3-kinase/phosphoinositide-dependent protein kinase 1/protein kinase B (PI3K/PDK 1/Akt) pathways. Taken together, all the results demonstrated that DHM-induced autophagy inhibited the cell proliferation in HepG2 cells, the possible mechanism involved in inhibition of mTOR activation and regulating the related upstream signaling pathways.

Dihydromyricetin induces cell cycle arrest and apoptosis in melanoma SK-MEL-28 cells.

Dihydromyricetin (DHM) exhibits multiple pharmacological activities; however, the role of DHM in anti-melanoma activities and the underlying molecular mechanisms are unclear. The aim of the present study was to evaluate the effects of DHM on cell proliferation, cell cycle distribution and apoptosis in the human melanoma SK-MEL-28 cell line, and to explore the related mechanisms. The effect of DHM on cell proliferation was investigated by MTT assay, and cell cycle distribution was determined by flow cytometry. TUNEL assay was used to evaluate DHM-mediated apoptosis, and western blotting was applied to examine expression levels of p53, p21, Cdc25A, Cdc2, P-Cdc2, Bax, IKK-α, NF-κB p65, p38 and P-p38 proteins. The results revealed that DHM suppressed cell proliferation of SK-MEL-28 cells in a concentration- and time-dependent manner, and caused cell cycle arrest at the G1/S phase. DHM increased the production of p53 and p21 proteins and downregulated the production of Cdc25A, Cdc2 and P-Cdc2 proteins, which induced cell cycle arrest. Additionally, DHM significantly induced the apoptosis of SK-MEL-28 cells, and enhanced the expression levels of Bax proteins and decreased the protein levels of IKK-α, NF-κB (p65) and P-p38. The results suggest that DHM may be a novel and effective candidate agent to inhibit the growth of melanoma.

Dihydromyricetin induces apoptosis and inhibits proliferation in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a life-threatening disease that is known to exhibit a poor prognosis. Therefore, it is important to identify an effective drug therapy for the treatment of HCC. Dihydromyricetin (DHM) is a flavonoid compound, isolated from the classical Chinese herb Ampelopsis grossedentata, which exhibits multiple pharmacological activities, including anticancer effects. In this study, the anticancer effect of DHM was investigated in nine different types of HCC cell lines via cell proliferation and immunoassays, as well as apoptosis detection. Two immortalized normal human liver cell lines were utilized to determine hepatotoxicity. The results revealed that DHM significantly inhibited cell proliferation and induced cell apoptosis in the HCC cell lines. However, DHM exhibited no cytotoxicity to normal human hepatic cell lines. Furthermore, it was found that DHM induced cell apoptosis in a p53-dependent manner. DHM upregulated p53 expression, and the upregulation of p53 increased the levels of the cleaved caspase-3 protein, directly inducing cell apoptosis. These results indicate that DHM is a promising candidate for the treatment of HCC.

Mir-152 inhibits cell proliferation and colony formation of CD133+ liver cancer stem cells by targeting KIT

AbstractmiR152 is involved in diverse biological functions and development of disease. This study investigates the role of mir-152 in cell proliferation and colony formation of liver cancer stem cells. We show that exogenous overexpression of mir-152 suppresses cell proliferation and colony formation in CD133+ hep3B cells. We also show that KIT is a direct target of miR-152 and miR-152 downregulates protein expression of KIT by directly binding to 3′ untranslated region of KIT. Downregulation of KIT by specific siRNAs inhibits proliferation and colony formation of CD133+ hep3B cells, which is similar to inhibitory effects of miR-152. Moreover, exogenous expression of KIT compromises inhibitory effects of miR-152 on cell proliferation and colony formation. Our findings suggest that mir-152 inhibits cell proliferation and colony formation of CD133+ hep3B cells by targeting KIT.

Dihydromyricetin inhibits migration and invasion of hepatoma cells through regulation of MMP-9 expression

AIM To investigate the effects of dihydromyricetin (DHM) on the migration and invasion of human hepatic cancer cells. METHODS The hepatoma cell lines SK-Hep-1 and MHCC97L were used in this study. The cells were cultured in RPIM-1640 medium supplemented with 10% fetal bovine serum at 37 °C in a humidified 5% CO2 incubator. DHM was dissolved in dimethyl sulfoxide and diluted to various concentrations in medium before applying to cells. MTT assays were performed to measure the viability of the cells after DHM treatment. Wound healing and Boyden transwell assays were used to assess cancer cell motility. The invasive capacity of cancer cells was measured using Matrigel-coated transwell chambers. Matrix metalloproteinase (MMP)-2/9 activity was examined by fluorescence analysis. Western blot was carried out to analyze the expression of MMP-2, MMP-9, p-38, JNK, ERK1/2 and PKC-δ proteins. All data were analyzed by Students t tests in GraphPad prism 5.0 software and are presented as mean ± SD. RESULTS DHM was found to strongly inhibit the migration of the hepatoma cell lines SK-Hep-1 (without DHM, 24 h: 120 ± 8 μmol/L vs 100 μmol/L DHM, 24 h: 65 ± 10 μmol/L, P < 0.001) and MHCC97L (without DHM, 24 h: 126 ± 7 μmol/L vs 100 μmol/L DHM, 24 h: 74 ± 6 μmol/L, P < 0.001). The invasive capacity of the cells was reduced by DHM treatment (SK-Hep-1 cells without DHM, 24 h: 67 ± 4 μmol/L vs 100 μmol/L DHM, 24 h: 9 ± 3 μmol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 117 ± 8 μmol/L vs 100 μmol/L DHM, 24 h: 45 ± 2 μmol/L, P < 0.001). MMP2/9 activity was also inhibited by DHM exposure (SK-Hep-1 cells without DHM, 24 h: 600 ± 26 μmol/L vs 100 μmol/L DHM, 24 h: 100 ± 6 μmol/L, P < 0.001; MHCC97L cells without DHM, 24 h: 504 ± 32 μmol/L vs 100 μmol/L DHM 24 h: 156 ± 10 μmol/L, P < 0.001). Western blot analysis showed that DHM decreased the expression level of MMP-9 but had little effect on MMP-2. Further investigation indicated that DHM markedly reduced the phosphorylation levels of p38, ERK1/2 and JNK in a concentration-dependent manner but had no impact on the total protein levels. In addition, PKC-δ protein, a key protein in the regulation of MMP family protein expression, was up-regulated with DHM treatment. CONCLUSION These findings demonstrate that DHM inhibits the migration and invasion of hepatoma cells and may serve as a potential candidate agent for the prevention of HCC metastasis.

Dihydromyricetin induces mouse hepatoma Hepal-6 cell apoptosis via the transforming growth factor-β pathway

Dihydromyricetin (DHM) is a flavonoid compound which possesses potent antitumor activity. In the present study, it was demonstrated that DHM significantly inhibited proliferation and induced apoptosis in mouse hepatocellular carcinoma Hepal-6 cells. Transforming growth factor β (TGF-β) is recognized as a major profibrogenic cytokine and is therefore a common target for drugs in the treatment of liver disease. The present study aimed to investigate whether TGF-β was involved in DHM-triggered cell-viability inhibition and apoptosis induction. An MTT assay was used to evaluate the viability of Hepal-6 cells following DHM treatment. TGF-β signalling is mediated by Smads and nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a crucial regulator of reactive oxygen species ROS production. TGF-β, Smad3, phosphorylated (p)-Smad2/3 and NOX4 protein expression levels were evaluated by western blot analysis. TGF-β and NOX4 gene expression levels were determined by quantitative polymerase chain reaction. The results indicated that DHM downregulated TGF-β, Smad3, p-Smad2/3 and NOX4 in a concentration-dependent manner. A cell counting assay indicated that DHM also inhibited Hepal-6 cell growth in a concentration-dependent manner. TGF-β expression was significantly decreased following DHM treatment. In conclusion, the results of the present study defined and supported a novel function for DHM, indicating that it induced cell apoptosis by downregulating ROS production via the TGF-β/Smad3 signaling pathway in mouse hepatocellular carcinoma Hepal-6 cells.