Platycodin D, a bioactive component of Platycodon grandiflorum, induces cancer cell death associated with extreme vacuolation.

Platycodin D (PD) is a major active component of the roots of Platycodon grandiflorum (Jacq.) A.DC. and possesses multiple biological and pharmacological properties, including anti-cancer activity. The aim of this study was to characterize PD-induced cytoplasmic vacuolation in human cancer cells and investigate the underlying mechanisms. PD-induced cancer cell death was associated with cytoplasmic pinocytic and autophagic vacuolation. Cellular energy levels were decreased by this compound, leading to the activation of AMP-activated protein kinase (AMPK). Additionally, compound C, an inhibitor of AMPK, completely prevented PD-induced vacuolation. These results suggest that PD induces cancer cell death, associated with excessive vacuolation through AMPK activation when cellular energy levels are low. Therefore, our findings provide a mechanistic rationale for a novel combinatorial approach using PD to treat cancer.

Protein S-glutathionylation induced by hypoxia increases hypoxia-inducible factor-1α in human colon cancer cells.

Hypoxia is a common characteristic of many types of solid tumors. Intratumoral hypoxia selects for tumor cells that survive in a low oxygen environment, undergo epithelial-mesenchymal transition, are more motile and invasive, and show gene expression changes driven by hypoxia-inducible factor-1α (HIF-1α) activation. Therefore, targeting HIF-1α is an attractive strategy for disrupting multiple pathways crucial for tumor growth. In the present study, we demonstrated that hypoxia increases the S-glutathionylation of HIF-1α and its protein levels in colon cancer cells. This effect is significantly prevented by decreasing oxidized glutathione as well as glutathione depletion, indicating that S-glutathionylation and the formation of protein-glutathione mixed disulfides is related to HIF-1α protein levels. Moreover, colon cancer cells expressing glutaredoxin 1 are resistant to inducing HIF-1α and expressing hypoxia-responsive genes under hypoxic conditions. Therefore, S-glutathionylation of HIF-1α induced by tumor hypoxia may be a novel therapeutic target for the development of new drugs.

Anti-inflammatory evaluation of the methanolic extract of Taraxacum officinale in LPS-stimulated human umbilical vein endothelial cells.

BACKGROUND: Atherosclerosis is a chronic vascular inflammatory disease. Since even low-level endotoxemia constitutes a powerful and independent risk factor for the development of atherosclerosis, it is important to find therapies directed against the vascular effects of endotoxin to prevent atherosclerosis. Taraxacum officinale (TO) is used for medicinal purposes because of its choleretic, diuretic, antioxidative, anti-inflammatory, and anti-carcinogenic properties, but its anti-inflammatory effect on endothelial cells has not been established. METHODS: We evaluated the anti-inflammatory activity of TO filtered methanol extracts in LPS-stimulated human umbilical vein endothelial cells (HUVECs) by monocyte adhesion and western blot assays. HUVECs were pretreated with 100 µg/ml TO for 1 h and then incubated with 1 µg/ml LPS for 24 h. The mRNA and protein expression levels of the targets (pro-inflammatory cytokines and adhesion molecules) were analyzed by real-time PCR and western blot assays. We also preformed HPLC analysis to identify the components of the TO methanol extract. RESULTS: The TO filtered methanol extracts dramatically inhibited LPS-induced endothelial cell-monocyte interactions by reducing vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, and pro-inflammatory cytokine expression. TO suppressed the LPS-induced nuclear translocation of NF-κB, whereas it did not affect MAPK activation. CONCLUSIONS: Our findings demonstrated that methanol extracts of TO could attenuate LPS-induced endothelial cell activation by inhibiting the NF-κB pathway. These results indicate the potential clinical benefits and applications of TO for the prevention of vascular inflammation and atherosclerosis.

Testosterone Regulates NUCB2 mRNA Expression in Male Mouse Hypothalamus and Pituitary Gland.

Nesfatin-1/NUCB2 is known to take part in the control of the appetite and energy metabolism. Recently, many reports have shown nesfatin-1/NUCB2 expression and function in various organs. We previously demonstrated that nesfatin-1/NUCB2 expression level is higher in the pituitary gland compared to other organs and its expression is regulated by 17ß-estradiol and progesterone secreted from the ovary. However, currently no data exist on the expression of nesfatin-1/NUCB2 and its regulation mechanism in the pituitary of male mouse. Therefore, we examined whether nesfatin-1/NUCB2 is expressed in the male mouse pituitary and if its expression is regulated by testosterone. As a result of PCR and western blotting, we found that a large amount of nesfatin-1/NUCB2 was expressed in the pituitary and hypothalamus. The NUCB2 mRNA expression level in the pituitary was decreased after castration, but not in the hypothalamus. In addition, its mRNA expression level in the pituitary was increased after testosterone treatment in the castrated mice, whereas, the expression level in the hypothalamus was significantly decreased after the treatment with testosterone. The in vitro experiment to elucidate the direct effect of testosterone on NUCB2 mRNA expression showed that NUCB2 mRNA expression was significantly decreased with testosterone in cultured hypothalamus tissue, but increased with testosterone in cultured pituitary gland. The present study demonstrated that nesfatin-1/NUCB2 was highly expressed in the male mouse pituitary and was regulated by testosterone. This data suggests that reproductive-endocrine regulation through hypothalamus-pituitary-testis axis may contribute to NUCB2 mRNA expression in the mouse hypothalamus and pituitary gland.