No abstract

Leptin, a hormone mainly produced from adipose tissue, has been shown to induce proliferation of cancer cells. However, the molecular mechanisms underlying leptin-induced tumor progression have not been clearly elucidated. In the present study, we investigated the role of autophagy in leptin-induced cancer cell proliferation using human hepatoma (HepG2) and breast cancer cells (MCF-7), and tumor growth in a xenograft model. Herein, we showed that leptin treatment caused autophagy induction as assessed by increase in expression of autophagy-related genes, including beclin-1, Atg5 and LC3 II, further induction of autophagosome formation and autophagic flux. Interestingly, inhibition of autophagic process by treatment with inhibitors and LC3B gene silencing blocked leptin-induced increase in cell number and suppression of apoptosis, indicating a crucial role of autophagy in leptin-induced tumor progression. Moreover, gene silencing of p53 or FoxO3A prevented leptin-induced LC3 II protein expression, suggesting an involvement of p53/FoxO3A axis in leptin-induced autophagy activation. Leptin administration also accelerated tumor growth in BALB/c nude mice, which was found to be autophagy dependent. Taken together, our results demonstrate that leptin-induced tumor growth is mediated by autophagy induction and autophagic process would be a promising target to regulate development of cancer caused by leptin production.

Punica granatum is commonly used in Korea as a traditional medicine for the treatment of pathogenic bacteria. In this study, we investigated the in vitro and in vivo antimicrobial activity of P. granatum peel EtOH extract (PGPE) against 16 strains of Salmonella. The minimal inhibitory concentrations of PGPE were in the range of 62.5–1000 x03BCg mL−1. In addition, the in vivo antibacterial activity of the PGPE extract was examined in a S. typhimurium infection mouse model. Mice were initially infected with S. typhimurium and then with PGPE. The extract was found to have significant effects on mortality and the numbers of viable S. typhimurium recovered from feces. Although clinical signs and histological damage were rarely observed in the treated mice, the untreated controls showed signs of lethargy and histological damage in the liver and spleen. Taken together, the results of this study indicate that PGPE has the potential to provide an effective treatment for salmonellosis.

No abstract

Ecklonia cava is a brown alga (Laminariales, Phaeophyta) growing on the subtidal rocky shores of Korea. It has antioxidant, antidiarrhea, and anticoagulant effects. In this study, the antimicrobial activity of E. cava EtOH extract and its fractions (n-hexane, CH2Cl2, EtOAc, n-BuOH, and H2O) were investigated against methicillin-resistant Staphylococcus aureus and Salmonella spp. The E. cava EtOAc fraction showed good antibacterial activity against all bacteria. Eckol isolated from E. cava EtOAc fraction showed antimicrobial activity against all the tested strains. The minimum inhibitory concentration of eckol against S. aureus strains ranged from 125 to 250 microg/mL and 125 to 250 microg/mL for Salmonella strains. The fraction inhibitory concentration index of eckol in combination with ampicillin ranged from 0.31 to 0.5, indicating remarkable synergism against S. aureus. However, against Salmonella gallinarum ATCC 9184 and Salmonella typhimurium, it ranges from 0.75 to 1.0. The combinations of eckol + ampicillin exhibited improved inhibition of S. aureus and Salmonella with synergy or additive effect. We suggest that eckol ingredients of the E. cava against S. aureus and Salmonella have antibacterial activity.