Anti-proliferative effects of recombinant iron superoxide dismutase on HepG2 cells via a redox-dependent PI3k/Akt pathway

• Published in: Applied microbiology and biotechnology Vol. 76; no. 1; pp. 193 - 201
• Main Authors: Lu, Min, Bi, Chong-shan, Gong, Xing-guo, Chen, Han-min, Sheng, Xie-huang, Deng, Tong-le, Xu, Ke-di
• Format: Journal Article
• Language: English
• Published: Berlin Berlin/Heidelberg : Springer-Verlag 01.08.2007; Springer; Springer Nature B.V
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Anions; antibodies; antineoplastic agents; Antitumor agents; bacterial proteins; Biological and medical sciences; biosynthesis; Biotechnology; Cell activation; Cell cycle; cell growth; Cell Line, Tumor; Cell Line, Tumor - cytology; Cell Proliferation; Cell Proliferation - drug effects; chromatography; Column chromatography; cytology; Dephosphorylation; drug effects; E coli; Enzymes; Escherichia coli; Fundamental and applied biological sciences. Psychology; G1 phase; genetics; genome; Glutathione; Hepatocytes; human cell lines; Humans; Hydrogen peroxide; interphase; Iron; Iron superoxide dismutase; Kinases; Liver cancer; liver neoplasms; metabolism; neoplasm cells; Nostoc; Nostoc commune; Nostoc commune - metabolism; Oxidation; Oxidation-Reduction; Oxidative Stress; Oxidative Stress - physiology; pharmacology; Phosphatidylinositol; phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; physiology; PI3k/Akt pathway; Protein Serine-Threonine Kinases; Protein-Serine-Threonine Kinases - metabolism; Protein-serine/threonine kinase; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-akt - metabolism; Reactive Oxygen Species; Reactive Oxygen Species - metabolism; Recombinant Proteins; Recombinant Proteins - biosynthesis; Recombinant Proteins - pharmacology; Signal Transduction; superoxide anion; Superoxide anions; Superoxide dismutase; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Superoxide Dismutase - pharmacology; Tumor cells; Tumors; Superoxide dismutase; Iron; Oxidoreductases; Enzyme
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-007-0939-3

The coding sequence for an iron superoxide dismutase (fe-sod) was amplified from the Nostoc commune genome. Recombinant Fe-SOD was overexpressed in Escherichia coli, accounting for ~76% of total bacterial protein. Fe-SOD was purified from bacterial lysate by Ni-NTA column chromatography and used to generate an anti-SOD antibody. The purified Fe-SOD was encapsulated in liposomes and delivered to HepG2 liver tumor cells to eliminate cellular superoxide anions. The SOD-loaded cells exhibited lower reactive oxygen species (ROS) levels and higher reduced glutathione (GSH) levels. In Fe-SOD-treated cells, the cell cycle was delayed in the G₁ phase, and HepG2 cell growth slowed in association with dephosphorylation of the serine-threonine kinase Akt. Low-dose H₂O₂ stimulated Akt phosphorylation, implying that Akt activation in HepG2 cells is redox-sensitive. Akt phosphorylation was abrogated by phosphatidylinositol 3-kinase (PI3K) inhibitors, suggesting that PI3K is an upstream mediator of Akt activation in HepG2 cells. This study provides insight into recombinant Fe-SOD-induced signaling mechanisms in liver tumor cells and suggests the feasibility of using Fe-SOD as an antitumor agent.