Evaluation of antiulcer agents with a human adenocarcinoma cell line (AGS)

Gastroprotective mechanisms of action of semisynthetic carnosic acid derivatives in human cells

Carnosic acid (CA) and its semisynthetic derivatives display relevant gastroprotective effects on HCl/ethanol induced gastric lesions in mice. However, little is known on the mechanisms of action of the new compounds. The aim of the present work was to assess the gastroprotective action mechanisms of CA and its derivatives using human cell culture models. A human gastric adenocarcinoma cell line (AGS) and lung fibroblasts (MRC-5) were used to reveal the possible mechanisms involved. The ability of the compounds to protect cells against sodium taurocholate (NaT)-induced damage, and to increase the cellular reduced glutathione (GSH) and prostaglandin E₂ (PGE₂) content was determined using AGS cells. Stimulation of cell proliferation was studied employing MRC-5 fibroblasts. Carnosic acid and its derivatives 10–18 raised GSH levels in AGS cells. While CA did not increase the PGE₂ content in AGS cells, all derivatives significantly stimulated PGE₂ synthesis, the best effect being found for the 12-O-indolebutyrylmethylcarnosate 13. A significant increase in MRC-5 fibroblast proliferation was observed for the derivatives 7 and 16–18. The antioxidant effect of the compounds was assessed by the inhibition of lipid peroxidation in human erythrocyte membranes, scavenging of superoxide anion and DPPH discoloration assay. The new CA derivatives showed gastroprotective effects by different mechanisms, including protection against cell damage induced by NaT, increase in GSH content, stimulation of PGE₂ synthesis and cell proliferation.

Identification and functional validation of caldesmon as a potential gastric cancer metastasis-associated protein

In this study, we aim to identify biomarkers for gastric cancer metastasis using a quantitative proteomics approach. The proteins extracted from a panel of 4 gastric cancer cell lines, two derived from primary cancer (AGS, FU97) and two from lymph node metastasis (AZ521, MKN7), were labeled with iTRAQ (8-plex) reagents and analyzed by 2D-LC-MALDI-TOF/TOF MS. In total, 641 proteins were identified with at least a 95% confidence. Using cutoff values of >1.5 and <0.67, 19 proteins were found to be up-regulated and 34 were down-regulated in the metastatic versus primary gastric cancer cell lines respectively. Several of these dysregulated proteins, including caldesmon, were verified using Western blotting. It was found that caldesmon expression was decreased in the two metastasis-derived cell lines, and this was confirmed by further analysis of 7 gastric cancer cell lines. Furthermore, immunohistochemical staining of 9 pairs of primary gastric cancer and the matched lymph node metastasis tissue also corroborated this observation. Finally, knockdown of caldesmon using siRNA in AGS and FU97 gastric cancer cells resulted in an increase in cell migration and invasion, while the overexpression of caldesmon in AZ521 cells led to a decrease in cell migration and invasion. This study has thus established the potential role of caldesmon in gastric cancer metastasis, and further functional studies are underway to delineate the underlying mechanism of action of this protein.

Development of novel nanoparticles shelled with heparin for berberine delivery to treat Helicobacter pylori

Various approaches have been proposed to overcome the unpleasant side-effects associated with antibiotic treatment for Helicobacter pylori. The limited effectiveness of such approaches has forced researchers to consider alternative strategies to eliminate H. pylori infection. The plant alkaloid berberine is known to significantly reduce proliferation of H. pylori. To localize berberine to the site of H. pylori infection, this study developed a novel nanoparticle berberine carrier with a heparin shell. Analysis of a simulated gastrointestinal medium indicated that the proposed in vitro drug carrier system effectively controlled the release of berberine, which interacted specifically with the intercellular space at the site of H. pylori infection. Furthermore, the prepared nanoparticles significantly increased the suppressive effect of berberine on H. pylori growth while efficiently reducing cytotoxic effects in H. pylori-infected cells.

Development of novel nanoparticles shelled with heparin for berberine delivery to treat Helicobacter pylori

Various approaches have been proposed to overcome the unpleasant side-effects associated with antibiotic treatment for Helicobacter pylori. The limited effectiveness of such approaches has forced researchers to consider alternative strategies to eliminate H. pylori infection. The plant alkaloid berberine is known to significantly reduce proliferation of H. pylori. To localize berberine to the site of H. pylori infection, this study developed a novel nanoparticle berberine carrier with a heparin shell. Analysis of a simulated gastrointestinal medium indicated that the proposed in vitro drug carrier system effectively controlled the release of berberine, which interacted specifically with the intercellular space at the site of H. pylori infection. Furthermore, the prepared nanoparticles significantly increased the suppressive effect of berberine on H. pylori growth while efficiently reducing cytotoxic effects in H. pylori-infected cells.