Mitochondrial Targeting of a Catalase Transgene Product by Plasmid Liposomes Increases RadioresistanceIn VitroandIn Vivo

Abstract

To determine whether increased mitochondrially localized catalase was radioprotective, a human catalase transgene was cloned into a small pSVZeo plasmid and localized to the mitochondria of 32D cl 3 cells by adding the mitochondrial localization sequence of MnSOD (mt-catalase). The cell lines 32D-Cat and 32D-mt-Cat had increased catalase biochemical activity as confirmed by Western blot analysis compared to the 32D cl 3 parent cells. The MnSOD-overexpressing 32D cl 3 cell line, 2C6, had decreased baseline catalase activity that was increased in 2C6-Cat and 2C6-mt-Cat subclonal cell lines. 32D-mt-Cat cells were more radioresistant than 32D-Cat cells, but both were radioresistant relative to 32D cl 3 cells. 2C6-mt-Cat cells but not 2C6-Cat cells were radioresistant compared to 2C6 cells. Intratracheal injection of the mt-catalase-plasmid liposome complex (mt-Cat-PL) but not the catalase-plasmid liposome complex (Cat-PL) increased the resistance of C57BL/6NHsd female mice to 20 Gy thoracic irradiation compared to MnSOD-plasmid liposomes. Thus mitochondrially targeted overexpression of the catalase transgene is radioprotective in vitro and in vivo.

Superoxide Dismutase Mimics: Chemistry, Pharmacology, and Therapeutic Potential

“…Along with our in vitro data (346) on cytoxic effects of MnPs through H 2 O 2 production when combined with ascorbate, several other groups reported that overexpression of MnSOD kills tumors through H 2 O 2 production (101,130,152,190). We hope that future studies will provide deeper insight into anti-vs. prooxidative actions of compounds (endogenous or exogenous) that are presently primarily considered antioxidants.…”

“…A mechanism whereby H 2 O 2 was produced suggested a prooxidative mode of anticancer action of MnPs in the presence of cellular reductants (346). A prooxidative mode of action has been proposed to explain the anticancer effects of the MnSOD enzyme itself by several groups (101,190). A prooxidative action of metalloporphyrins was also reported by others (161,234,253).…”

Receptor-interacting Protein 1 Increases Chemoresistance by Maintaining Inhibitor of Apoptosis Protein Levels and Reducing Reactive Oxygen Species through a microRNA-146a-mediated Catalase Pathway

“…Suppressing this RIP1-mediated catalase expression pathway may sensitize chemotherapy. Indeed, ectopic catalase expression increases radioresistance in vitro and in vivo (34), and targeting tumor cell-protective catalase has been proposed for anticancer therapy (35).…”

Global analysis of CpG methylation reveals epigenetic control of the radiosensitivity in lung cancer cell lines

“…Recent study revealed that overexpression of CAT increased radioresistance (Epperly et al, 2009). In addition, BNC1 is known to be involved in cell proliferation of keratinocytes (Tseng and Green, 1994), but the function of this gene has not yet been clearly defined.…”

“…Antioxidants such as CAT, superoxide dismutase, glutathione peroxidase and glutathione reductase were activated on exposure to ionizing radiation. Upregulation of antioxidant proteins led to radioresistance (Epperly et al, 2009) and resistance to the antitumor agent cisplatin (Wang et al, 2008). Hypomethylation of the CAT gene at exon 2 was detected in colon tumor specimens (Ribieras et al, 1994).…”