| Background: Lung cancer is one of the most important factors that endanger human health.According to the latest statistics of the World Health Organization,the incidence and mortality of lung cancer in malignant tumors in all populations are second and first respectively.In 2020,there were be 2.2 million new cases of lung cancer and1.79 million deaths,accounting for nearly one-fifth(18%)of cancer deaths.Traditional treatment(surgery,radiation therapy,and chemotherapy)are still the standard treatment for lung cancer.Improving the tumor control rate and survival period of patients,and reducing the toxic and side effects of treatment are the goals pursued by scientific researchers.Objective: This study utilizes the high heterogeneity of tumor cell metabolism and reprogramming,and uses a modified ketogenic diet combined with radiotherapy.From the perspective of energy metabolism and tumor microenvironment,this study explored and analyzed the radiotherapy of the modified ketogenic diet on LLC tumor-bearing mice sensitivity research.Methods: Chosen 6-8 weeks old female C57BL/6J mice of about 18 g to establish a lung cancer model,and given different glycolipid ratios(48%: 15%,35%: 30%,20%:45%,5%: 60%)feed combined with radiotherapy,monitored and observed mouse volume,tumor size,blood glucose level,blood ketone level,survival and safety studies;CCK8 detected different glucose concentrations(2.78 m M,5.56 m M,12.5m M and25 m M)and β-hydroxybutyrate(βHB,0m M,5m M,10 m M)combined with radiotherapy on the proliferation of LLC cells;flow cytometry to detected tumor cell cycle and apoptosis;immunofluorescence to detect radiotherapy-induced DNA damage markerγH2AX and tumors the distribution of immune cells in the tumor tissues;immunohistochemistry and VG staining to detect the expression of tumor-related angiogenesis CD34 and collagen fibers;western blot to detect the expression and activation of AMPK.Results:(1)The 45F+RT group was screened out of LLC tumor-bearing mice fed with a diet with different glycolipid energy ratios,and the 45F+RT group had the best tumor control and longer survival time,while the median survival time of the PT group was 38 Days,55 days for the PT+RT group,41 days for the 45 F group,but not for the45F+RT group;HE staining showed no tumor metastasis and liver and kidney toxic side effects.(2)The effects of different concentrations of glucose and β-hydroxybutyrate(βHB)on the proliferation of LLC cells,the results showed that: The glucose concentration was 5.56 m M and 2.78 m M,respectively,with the increase of radiation dose,the survival rate of LLC cells significantly decreases;However,the cell survival rate in the low-sugar medium with βHB was significantly lower than that in the control group,and the survival rate of LLC decreased significantly with the extension of the culture time after irradiation(p <0.001).Compared with the control group,the LG(low glucose)group,LG+βHB 5m M group,LG+βHB 10 m M group had a significant increase in the proportion of G2 phase,and the proportion of early and late apoptosis.(3)By detecting the formation of γH2AX foci after radiotherapy,the results showed that the LG group,LG + βHB 5m M group and LG + βHB 10 m M group had more γH2AX foci formation than the control group after 2h and 24 h after radiotherapy,and there was a statistical difference(P <0.05).(4)Through changes in tumor microenvironment,the results of this study showed that the modified ketogenic diet combined with radiotherapy could down-regulate the expression of collagen fiber and CD34,up-regulate the expression of CD8 and down-regulate the expression of PD1 in tumor tissues.Conclusion: The modified ketogenic diet could enhance the antitumor effect of radiotherapy in LLC tumor-bearing mice by reducing glucose and increasing the fat-to-energy ratio.The addition of βHB in low-glucose medium could enhance the radiotherapy sensitivity by affecting cell cycle and tumor cell apoptosis,increasing DNA damage and inhibiting LLC proliferation.The combination of modified ketogenic diet and radiotherapy can regulate the microangiogenesis of tumor microenvironment and enhance the killing effect of immune effect on tumor cells. |
