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Background: Daptomycin is a recently introduced, last-resort antibiotic that displays a unique mode of action against Gram-positive bacteria that is not fully understood. Several bacterial targets have been proposed but no human binding partner is known. Methods: In the present study we tested daptomycin in cell viability and proliferation assays against six human cell lines, describe the synthesis of biotinylated and fluorescently labeled analogues of daptomycin. Biotinylated daptomycin was used as bait to isolate the human binding partner by the application of reverse chemical proteomics using T7 phage display of five human tumor cDNA libraries. The interaction between the rescued protein and daptomycin was validated via siRNA knockdown, DARTS assay and immunocytochemistry. Results: We have found that daptomycin possesses selective growth inhibition of some cancer cell lines, especially MCF7. The unbiased interrogation of human cDNA libraries, displayed on bacteriophage T7, revealed a single human target of daptomycin; ribosomal protein S19. Using a drug affinity responsive target stability (DARTS) assay in vitro, we show that daptomycin stabilizes RPS19 toward pronase. Fluorescently labeled daptomycin stained specific structures in HeLa cells and co-localized with a RPS19 antibody. Conclusion: This study provides, for the first time, a human protein target of daptomycin and identifies RPS19 as a possible anticancer drug target for the development of new pharmacological applications and research. [ABSTRACT FROM AUTHOR]

Background: Curcumin, a major active component of turmeric, has previously been reported to alleviate liver damage. Here, we investigated the mechanism by which turmeric and curcumin protect the liver against carbon tetrachloride (CCl4)-induced injury in rats. We hypothesized that turmeric extract and curcumin protect the liver from CCl4-induced liver injury by reducing oxidative stress, inhibiting lipid peroxidation, and increasing glutathione peroxidase activation. Methods: Chronic hepatic stress was induced by a single intraperitoneal injection of CCl4 (0.1 ml/kg body weight) into rats. Turmeric extracts and curcumin were administered once a day for 4 weeks at three dose levels (100, 200, and 300 mg/kg/day). We performed ALT and AST also measured of total lipid, triglyceride, cholesterol levels, and lipid peroxidation. Result: We found that turmeric extract and curcumin significantly protect against liver injury by decreasing the activities of serum aspartate aminotransferase and alanine aminotransferase and by improving the hepatic glutathione content, leading to a reduced level of lipid peroxidase. Conclusions: Our data suggest that turmeric extract and curcumin protect the liver from chronic CCl4-induced injury in rats by suppressing hepatic oxidative stress. Therefore, turmeric extract and curcumin are potential therapeutic antioxidant agents for the treatment of hepatic disease. [ABSTRACT FROM AUTHOR]

Background: Epigenetic modifications play a critical role in the regulation of all DNA-based processes, such as transcription, repair, and replication. Inappropriate histone modifications can result in dysregulation of cell growth, leading to neoplastic transformation and cell death. Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation. Preclinical models have revealed that histone gene modifiers and epigenetic alterations play important roles in renal cell carcinoma (RCC) tumorigenesis. Recently, a novel HDAC inhibitor, N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), has been introduced as an example of a new class of anti-cancer agents. The anti-cancer activity of HNHA and the underlying mechanisms of action remain to be clarified. Methods: The MTS assay using a panel of RCC cells was used to evaluate the anti-proliferative effects of HNHA. The established HDAC inhibitors, SAHA and TSA, were used for comparison. Western blotting analysis was performed to investigate the acetylation of histone H3 and the expression of apoptotic markers in vitro and in vivo. Subcellular fractionation was performed to evaluate expression of Bax and cytochrome c in the cytosol and mitochondria, and also translocation of cytochrome c from the cytoplasm to the nucleus. A confocal microscopic evaluation was performed to confirm inhibition of cell proliferation, induction of apoptosis, and the nuclear translocation of cytochrome c in RCC cells. Results: In this study, we investigated the apoptosis-inducing activity of HNHA in cultured kidney cancer cells. Apoptosis in the HNHA-treated group was induced significantly, with marked caspase activation and Bcl-2 suppression in RCC cells in vitro and in vivo. HNHA treatment caused cytochrome c release from mitochondria, which was mediated by increased Bax expression and caspase activation. HNHA also induced nuclear translocation of cytochrome c, suggesting that HNHA can induce caspase-independent nuclear apoptosis in RCC cells. An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors. Conclusions: HNHA has more potent anti-tumor activity than established HDAC inhibitors. Its activities are mediated by caspase-dependent and cytochrome-c-mediated apoptosis in RCC cells. These results suggest that HNHA may offer a new therapeutic approach to RCC. [ABSTRACT FROM AUTHOR]