Preparation of the spin trapping probe, N-tert-butyl-alpha-phenylnitrone, nanoparticle and its affinity to hepatoma cells / 药学学报

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.

Redox stress regulates cell proliferation and apoptosis of human hepatoma through Akt protein phosphorylation.

Employing a spin trapping agent combined with electron spin resonance spectroscopy, we were able to capture reactive oxygen species (ROS) in living hepatoma cells and first found that the trapped ROS was superoxide anion (O(2)(z.rad;-)). O(2)(z.rad;-) suppressed by treatment with diphenylene iodonium, a flavoprotein inhibitor, was generated by the flavoprotein-containing NADPH-oxidase complex. Applying endogenous/exogenous pro-oxidant or antioxidant causes different redox states in hepatoma cells. Akt activity and cell growth were significantly stimulated by treating hepatoma cells with low concentration of ROS, which could be abolished by adding antioxidants. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin (0.15 microM) inhibited Akt phosphorylation induced by ROS. Our results indicate that hepatoma cell growth is ROS-dependent, and fluctuation of the intracellular redox state may regulate hepatoma cell growth through Akt phosphorylation and the PI3K/Akt pathway, resulting in a broad array of responses from cellular proliferation to apoptosis.