Role of SOD in malignant tumor by anti cancer drugs

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Recently, many anti cancer drugs have been shown to produce super oxide anion (O_2^-) and seem to involve O_2^- in their mode of action. Ionizing radiation provokes the decomposition reaction of water, producing a variety of reactive oxygen species including O_2^-. The finding that cancer cells are generally low in SOD activity may offer a theoretical base for radiation therapy and chemotherapy. Thus, intracellular SOD level may be an important factor determining the resistance of cancer cells against anti cancer drugs or radiation.For this purpose, we analyzes the activity of tumor tissue SOD that probed tumor sample form patient at the first time visit, and at the operation. Treatment with anti cancer drugs or radiation a few increasea of SOD activity in tumor tissue. To analyzes the mechanisms of resistance of cancer cells against anti cancer drugs or radiation, xanthin and xanthin oxidase were employed to some tumor cell line as an O_2^- generating system, and treatment with 5-FU or CDDP or ionizing radiation. Treatment with anti cancer drugs or radiation a few increases of SOD activity in tumor cells. The treatment with TNF or INF-gamma did a small reduction of SOD activity in tumor cells. CuZnSOD, catalase and GSH-px mRNAs were up regulated by O_2^- exposure with in 20 minus.