Dong-Yun Shi

As a phytochemical derived from the roots of Salvia miltiorrhiza Bunge, Tanshinone IIA has been reported to possess anti-inflammatory and antioxidant activity. Studies in breast, colon, prostate and lung cancer indicate that Tanshinone IIA may exhibit a promising antitumor activity. However, systemic studies of the cytotoxic effects of Tanshinone IIA on gastric cancer have not been described. The present study offers a comprehensive evaluation of the antitumor effects of Tanshinone IIA in gastric cancer cells in vitro and in a mouse xenograft model. Cell viability and apoptosis in vitro were evaluated through the MTT assay and flow cytometry analysis. The results indicate that Tanshinone IIA can induce gastric cancer cell growth inhibition and apoptosis in a time- and concentration-dependent manner. Furthermore, we investigated the mechanism of the apoptotic effects induced by Tanshinone IIA. We found that Tanshinone IIA can not only cause cell cycle arrest in the G2/M phase, but also trigger the intrinsic apoptotic signaling pathway. The results suggest that Tanshinone IIA may serve as an effective adjunctive reagent in the treatment of gastric cancer.

The Warburg effect has been found in a wide spectrum of human cancers, however the underlying mechanisms are still unclear. This study aims to explore the role of cellular oxidative stress in relation to glycolysis and the Warburg effect in hepatoma cells.

This article describes the preparation of the N-tert-butyl-alpha-phenylnitrone (PBN) liposomes and their related characteristics. The PBN liposomes were prepared by film dispersion-supersonic method and the formula of liposomes was optimized by orthogonal uniform design. RP-HPLC was used to qualify the amount of PBN that entered into the hepatoma cells. Necrosis rate was also investigated by fluorescence activated cell sorter (FACS) after PBN liposomes transfection. Result showed that the mean particle size, entrapment efficiency, and polydispersity of the resulting PBN-liposome were 137.5 nm, 71.52% and 0.286, respectively. PBN liposomes can enter into the tumor cell stably and they have higher affinity to hepatoma cell compared with free PBN resulting in a higher necrosis rate after transfection. These results provide a potential method for early diagnosis and treatment of cancer using specific spin trapping probe targeting tumor cells.

In the present study, the relationship between PKB signaling and reactive oxygen species (ROS) during the course of exogenous and endogenous ROS or antioxidants regulating human 7721 hepatoma cell proliferation was studied. To change endogenous ROS levels, 7721 cells were transfected with human manganese superoxide dismutase (MnSOD) construct containing sense or antisense MnSOD cDNA. Low level of exogenous ROS H2O2(1-10 mumol/L) significantly stimulated PKB activity and c-fos/c-jun expression and cell growth, which could be abolished by antioxidant danshensu (40 mg/L). It was observed that overexpression of MnSOD inhibited 7721 cell growth by inhibiting PKB activity and c-fos/c-jun expression; the PKB activity and c-fos/c-jun expression, however, were stimulated by down-regulated MnSOD expression. In addition, PKB-7721 cells (transfected with sense PKB cDNA) promoted c-fos/c-jun expression by stimulating PKB activity. These results suggest that the redox state stimulated hepatoma cell growth through PKB pathway, which modulates AP-1 expression.

Kunming mice inoculated with hepatoma cell (H22) suspension subcutaneously at their right axilla were administered orally with antioxidants such as vitamine E, beta-carotene, glutamine, kappa-selenocarrageenan and polysaccharide-peptide of coriolus (PSP) solution. It was found that the inoculated hepatoma growth was suppressed to various extents. The two kinds of polysaccharide antioxidants improved non-specific immunity, enhanced the nitrogen monoxide (NO) content in plasma and strengthened the inhibition of hepatoma. Above antioxidants added in the culture of 7721 human hepatoma cells inhibited the cell proliferation and inducedits apoptosis. Meanwhile, the activity of glutathione peroxidase (GSH-Px) in the plasma of mice increased and the content of malondialdehyde (MDA) decreased. H(2)O(2) in low concentration improved the cancer cell proliferation and inhanced the expression of Mn-SOD c-fos and c-jun, but led to cells apoptosis or necrosis in high concentration. The mechanism of antioxidants inhibiting tumor growth and improving cancer cells apoptosis might be that, on the one hand, the antioxidants blocked the free radicals signal transduction on cancer cells proliferation, and on the other hand, they improved the release of NO through enhancing the non-specific immunity, so inhibiting the cancer cells proliferation directly.