Aspafilioside B induces G2/M cell cycle arrest and apoptosis by up-regulating H-Ras and N-Ras via ERK and p38 MAPK signaling pathways in human hepatoma HepG2 cells.

We recently establish that aspafilioside B, a steroidal saponin extracted from Asparagus filicinus, is an active cytotoxic component. However, its antitumor activity is till unknown. In this study, the anticancer effect of aspafilioside B against HCC cells and the underlying mechanisms were investigated. Our results showed that aspafilioside B inhibited the growth and proliferation of HCC cell lines. Further study revealed that aspafilioside B could significantly induce G2 phase cell cycle arrest and apoptosis, accompanying the accumulation of reactive oxygen species (ROS), but blocking ROS generation with N-acetyl-l-cysteine (NAC) could not prevent G2/M arrest and apoptosis. Additionally, treatment with aspafilioside B induced phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAP kinase. Moreover, both ERK inhibitor PD98059 and p38 inhibitor SB203580 almost abolished the G2/M phase arrest and apoptosis induced by aspafilioside B, and reversed the expression of cell cycle- and apoptosis-related proteins. We also found that aspafilioside B treatment increased both Ras and Raf activation, and transfection of cells with H-Ras and N-Ras shRNA almost attenuated aspafilioside B-induced G2 phase arrest and apoptosis as well as the ERK and p38 activation. Finally, in vivo, aspafilioside B suppressed tumor growth in mouse xenograft models, and the mechanism was the same as in vitro study. Collectively, these findings indicated that aspafilioside B may up-regulate H-Ras and N-Ras, causing c-Raf phosphorylation, and lead to ERK and p38 activation, which consequently induced the G2 phase arrest and apoptosis. This study provides the evidence that aspafilioside B is a promising therapeutic agent against HCC.

Curcumin Protects against 1-Methyl-4-phenylpyridinium Ion- and Lipopolysaccharide-Induced Cytotoxicities in the Mouse Mesencephalic Astrocyte via Inhibiting the Cytochrome P450 2E1.

Curcumin is extracted from the rhizomes of the ginger family plant Curcuma longa L., which has a good protection for liver, kidney, and immune system. However, there is little information about its contribution in protection of astrocytes recently. The present study was undertaken to elucidate the protective effect of curcumin, an herbal antioxidant, on 1-methyl-4-phenylpyridinium ion- (MPP(+)-) and lipopolysaccharide- (LPS-) induced cytotoxicities, as well as the underlying mechanisms by using primary mouse mesencephalic astrocytes. The results showed that curcumin protected the mesencephalic astrocytes from MPP(+)- and LPS-induced toxicities along with reducing reactive oxygen species (P < 0.05) and maleic dialdehyde (P < 0.05) sufficiently. Moreover, curcumin significantly inhibited the cytochrome P450 2E1 (CYP2E1) expression (P < 0.01 at mRNA level, P < 0.05 at protein level) and its activity (P < 0.05) sufficiently induced by MPP(+) and LPS in the mouse mesencephalic astrocytes. And curcumin as well as diallyl sulphide, a CYP2E1 positive inhibitor, ameliorated MPP(+)- and LPS-induced mouse mesencephalic astrocytes damage. Accordingly, curcumin protects against MPP(+)- and LPS-induced cytotoxicities in the mouse mesencephalic astrocyte via inhibiting the CYP2E1 expression and activity.

Fluoxetine induces hepatic lipid accumulation via both promotion of the SREBP1c-related lipogenesis and reduction of lipolysis in primary mouse hepatocytes.

AIMS: In this study, we investigated the peripheral mechanisms underlying the metabolic side effects of fluoxetine (FLX) by focusing on hepatic lipid metabolism. METHODS: Primary mouse hepatocytes were prepared from male mice by the two-step perfusion method. The lipid accumulation in primary mouse hepatocytes was analyzed via neutral oil staining. And the lipid metabolism enzymes were determined with RT-PCR and Western blot. RESULTS: Fluoxetine significantly induced the lipid accumulation in primary mouse hepatocytes. Moreover, FLX increased the acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FAS) expression, which are important enzymes in lipogenesis. Oppositely, Fluoxetine significantly decreased the carboxylesterase 3 (CES3) and carboxylesterase 1 (CES1) expression, which are related to lipolysis. Further study demonstrated FLX-activated SREBP1c, which is one of the most important transcription factors conducting coordinated transcriptional regulation of lipogenesis gene such as ACC1 and FAS. And the increase of lipogenesis gene (ACC1) was abolished by SB203580 but not by pyrrolidine dithiocarbamate (PDTC), suggesting through p38-MAPK pathway. CONCLUSION: Fluoxetine induces hepatic lipid accumulation via both promotion of the SREBP1c-related lipogenesis and reduction of lipolysis in primary mouse hepatocytes.

Down regulation of differentiated embryonic chondrocytes 1 (DEC1) is involved in 8-methoxypsoralen-induced apoptosis in HepG2 cells.

8-Methoxypsoralen (8-MOP), a naturally occurring compound, is a potent modulator of epidermal cell growth and differentiation in combination with ultraviolet light. However, there is little information on 8-MOP contribution to cell apoptosis alone. In the study, we evaluated 8-MOP, independently of its photoactivation, induced apoptosis in human hepatocellular carcinoma HepG2 cells. And we provide a molecular explanation linking 8-MOP to induce apoptosis. In HepG2 cells, treatment with 8-MOP induced the cell apoptosis in both dose-dependent and time-dependent manners. IC(50) values of 8-MOP were 8.775, 5.398 µM for 48 and 72 h, respectively. Further study showed that 8-MOP decreased the procaspase-3, procaspase-8, and procaspase-9, increased the ratio of Bax/Bcl-2 and decreased the survivin. Moreover, 8-MOP decreased differentiated embryonic chondrocyte gene1 (DEC1). Overexpression of DEC1 antagonized partially apoptosis induced by 8-MOP. And overexpression of DEC1 abolished the decrease of survivin and the activation of caspase-3 induced by 8-MOP partially. So, down regulation of DEC1 is involved in 8-MOP-induced apoptosis in HepG2 cells. Here, it is demonstrated that DEC1 possesses anti-apoptotic effects in 8-MOP-treated HepG2 cells. The findings provide more of a basis for 8-MOP as an anti-tumor agent in cancer therapy.