The Mechanism Research Of Contactless Water-cooled Microwave Radiation On Lung Carcinoma Bearing Mice

Objectives:To explore the relationship between the radiation power-time and the temperature change of the local tissues of mice under the non-contact water-cooled circulating microwave radiation,and to explore the safe radiation power and the heat conversion efficiency ratio compared with normal microwave.To study the effects of single microwave radiation and multiple microwave radiation on apoptosis of tumor cells in tumor-carrying mice of Lewis lung cancer,and the expression changes of apoptotic proteins and immune-related proteins in the process of apoptosis.Methods:The lung of male SD rats was exposed during surgery,and the left lung was uniformly radiated at the level of 1cm above the carina.The microwave ablation needle was placed in the tracheal cavity 1cm above the carina,and the temperature measuring probe was placed 1mm,3mm,5mm and 10 mm outside the tube cavity at the level of the ablation needle to measure the temperature.The power of 40 W,60W and 80 W was irradiated for 5 minutes,and the temperature of the probe was recorded at 1 minute,3 minutes and 5 minutes respectively.Repeat the experiment three times.A subcutaneous tumor-bearing model of Balb/C mice with lung cancer was established,and 40 tumor-bearing mice were randomly divided into 4 groups with 10 mice in each group.The four groups were sham operation group,single microwave irradiation group,multiple microwave irradiation group(once per week,4 times in total),and blank control group.The weight change and tumor length and diameter of mice were measured regularly,and tumor volume was obtained by calculating formula.Finally,the change curve was drawn according to the corresponding data.The tumor was taken one month later,and the histopathological morphology of the tumor was observed.The expression levels of apoptosis related proteins bcl-2,Bax,Caspase-3 and tumor immunorelated protein(PDL1)were detected by immunohistochemical staining,and confirmed by Western Blot.Results:When the microwave radiation power was 40 W and the radiation time was 5 minutes,the treatment effect was found in the lung parenchyma 5mm under the probe,and the effect on the surrounding normal tissues was minimal.Using this power density for microwave irradiation,it was found that the average tumor volume of the single and multiple microwave irradiation group was significantly smaller than that of the sham group(280.19±28.95mm3,178.67±38.54mm3,338.41±35.16mm3)(P<0.05).Continuous microwave irradiation upregulation of Bax protein expression(IOD 0.1123±0.023,SOD 1.3640±0.312)(P<0.05),Caspase3 protein expression upregulation(IOD 0.2733±0.024,SOD 2.9940±0.340)(P<0.05).The non-thermal effect of continuous microwave radiation has a cumulative effect,which can induce LLC apoptosis,accompanied by the increased expression levels of Caspase 3,Bax and other proteins.Western blot again verified the increased expression levels of Caspase 3,Bax and other proteins.Conclusions:Low power and short time of non-contact microwave irradiation lead to limited temperature increase of local normal tissues,which is safe.The non-thermal effect of microwave can effectively induce tumor cell apoptosis by upregulation of pro-apoptotic proteins,but has little effect on surrounding normal lung tissues.The application of low microwave intensity continuous radiation of water circulation under non-contact is expected to be used in the clinical treatment of non-small cell lung cancer.