The Relationship Between NADPH Oxidase And The Radiosensitivity Of Three Tumor Cells

Radiotherapy is one of three treatment means of cancer therapy.The mechanism of radiation-induced tumor cell death is often described in terms of indirect and direct effects.The indirect effect of radiation,play a main role,induce DNA breaks with the reactive species produced upon radiolysis of water molecules.The radiosensitivity of tumor cells are different,the difference may come from their own.In this study we use three kinds of tumor cell that have different radiosensitivity.We used immunofluorescence and western blot to detect the activity of NADPH oxidase and expression of gp91^phox and p47^phox after X-ray and ¹²C heavy ion irradiation.The results provide a new basis for the relationship between NADPH oxidase and the radiosensitivity.There is a novel way for the use of gene therapy to change the radiosensitivity of tumor cells.The results:1.The human hepatoma cell line HepG2,the human cervical carcinoma cell line HeLa and the human lung adenocarcinoma cell line GLC-82 were selected and the survival fraction at two grey of each cell line was detected with the method of MTT. The result showed that the SF2 of the three types of cells have discrepancy, suggesting that the three types of cell have different radiosensitivity.The hepatoma cell line were lowest,the cervical carcinoma cell line were middle,the lung adenocarcinoma cell line were highest.2.In this study,we found that the level of the total intracellular ROS was significantly increased in the three types of tumor cells after exposing to X-ray and the increase could be blocked by diphenyleneiodonium(DPI),an inhibitor of NADPH oxidase. This result imply that NADPH oxidase play an essential role in ROS production induced by X-ray in tumor cells.3.Detecting the activity of NADPH oxidase after X-ray and ¹²C heavy ion irradiation with the method of immunofluorescence,we found that radiation with different linear energy can activate NADPH oxidase,but have different effection on the activation. The effection of ¹²C heavy ion was higher than X-ray. 4.Using western blot to detect the changes in expression of the cytosolic subunit p47^phox and the the catalytic subunit gp91^phox,the result showed that irradiation can induced the increase of the gp91^phox expression,but not p47^phox,suggesting that the function of p47^phox has nothing to do with the expression.We radiated three types of tumor cell with the same dose of X-ray(12Gy),we found that gp91^phox expression of the three types of tumor cells with different radiosensitivity were different,implied that NADPH oxidase have relationship with radiosensitivity of tumor cells.