The Effects Of Different Exercise On DEN-induced Liver Tumor And Liver Lactate Metabolism

Background: The type of tumor cell metabolism is different from the normal cell metabolism.In an oxygen-rich environment,the metabolism of tumor cells is switched to glycolysis to produce a large amount of lactate.This phenomenon is called aerobic glycolysis or Warburg effect.Lactate is not only a metabolite during exercise,but also an important signaling molecule for the body regulation,especially in the process of tumor growth.Lactate acidifies the tumor microenvironment,providing a greenhouse environment for tumor growth,promoting tumor cell proliferation,immune escape,invasion and metastasis,and angiogenesis.The increase in lactate production during exercise is a normal physiological stress,but does the lactate produced by exercise further acidify the tumor microenvironment to promote tumorigenesis? It is well known that endurance exercise and high-intensity intermittent exercise start the body's energy supply system is very different,endurance exercise mainly relies on aerobic oxidation system to supply energy,lactate production is less,and high-intensity interval exercise mainly depends on ATP-phosphate creatine system and anaerobic breathing system,causing a large accumulation of lactate,endurance exercise and high-intensity interval exercise can improve the body's ability to clear lactate,but the effects of endurance exercise and high-intensity intermittent exercise on tumor lactate metabolism and its anti-tumor effect and mechanism are still unclear,still need to be further explore.Objective: The aim of this study was to investigate the effects of different exercise on diethylnitrosamine(DEN)-induced liver tumorigenesis.From the perspective of liver lactate metabolism,the mechanism of exercise anti-tumor and the difference between different exercises were revealed.It provide a strategy or basis for exercise anti-tumor.Methods: A total of 40 Male C57BL/6 mice were selected(3 weeks old),mice were randomly divided into 4 groups: NC group,control group;DEN group,diethyl nitrosamine injection control group;ET group,diethylnitrosamine injection group + moderate intensity endurance exercise group;HIT group,diethylnitrosamine injection group + high intensity interval exercise group.NC group: mice were intraperitoneally injected with saline at 3 weeks of age,25mg/kg.DEN group,ET group,HIT group: mice were injected intraperitoneally with diethylnitrosamine(DEN)at 3 weeks of age,25mg/kg.The ET group took endurance exercise at 8 weeks of age.The endurance exercise speed was 0.8 km/h,the exercise intensity was 65%-75% VO2 max,and the exercise time was 40 minutes,5 days/week.The HIT group took high-intensity interval exercise at 8 weeks of age.The high-intensity interval exercise speed was 1.5km/h,the exercise intensity was 90-100% VO2 max,the exercise time was 2min,and the rest time was 2min,alternating 8-10 times,5 days / week.Each group of mice underwent GTT test and ITT test at 12 weeks and 14 weeks of age,respectively.Each group of mice was tested for body composition at 23 weeks of age using a relaxation analysis and magnetic resonance-bulk magnetic resonance imaging analyzer.At the age of 27 weeks,mice in each group were anesthetized with isoflurane.Immediately,the blood was collected from the heart cavity of the mice and the liver tissues were taken.Elisa was used to detect the content of insulin in serum.The content of lactate,pyruvic acid and glucose in serum,the activity of lactate dehydrogenase in serum,the content of cytoplasmic lactate and mitochondrial lactate in liver,the activity of cytoplasmic lactate dehydrogenase,mitochondrial lactate dehydrogenase and phosphoenolpyruvate carboxykinase(PEPCK)in liver were detected by enzyme-labeled colorimetry.Realtime PCR was used to detect m RNA levels of LDHa,LDHd,LDH6 b,G6pase,Pck,Pcx,c GPD,m GPD,Pdha2,Pdk4,Pklr,Mpc2,Gpt2 in liver.Protein expression of LDHA,PCK1,G6 pase,P-AMPK/AMPK in the liver was detected by Western Blottig.Results:(1)The liver tumor incidence rate was 0% in the NC group,66.7% in the DEN group,62.5% in the HIT group,and 20% in the ET group.The liver tumor incidence rate showed that the liver tumor incidence rate was the lowest in the liver injury mice of the endurance exercise group.(2)Compared with the NC group,the fat percentage in the DEN group was significantly lower(p<0.001),and the fat percentage in the HIT group was significantly lower(p<0.05).Compared with the DEN group,the fat percentage in the ET group was significantly increased(p<0.01).Compared with the NC group,the lean body mass in the HIT group was significantly increased(p<0.05),the lean body weight in the ET group was significantly increased(p<0.05).(3)Compared with the DEN group,the serum lactate content in the HIT group was significantly increased(p<0.05),and there was no significant difference between the other groups.Compared with the DEN group,the serum pyruvate content in the HIT group was significantly increased(p<0.05),and there was no significant difference between the other groups.(4)Compared with the NC group,the m RNA levels of LDHa(p<0.05),LDH6b(p<0.001),and LDHd(p<0.01)in the mice liver of DEN group were significantly increased.Compared with the DEN group,the m RNA levels of LDHa(p<0.05),LDH6b(p<0.001)and LDHd(p<0.05)in the mice liver of HIT group were significantly decreased.The m RNA level of LDHa in the mice liver of ET group showed a trend of decrease,but no significant difference was observed.However,the m RNA levels of LDH6b(p<0.001)and LDHd(p<0.01)in the mice liver of ET group was significantly decreased.(5)Compared with the NC group,the m RNA levels of COXI(p<0.001),ND1(p<0.05),and CYTb(p<0.05)in the mice liver of ET group were significantly increased.Compared with the DEN group,the m RNA levels of COXI(p<0.01),ND1(p<0.01)and CYTb(p<0.05)in the mice liver of ET group were significantly increased.Compared with the HIT group,the m RNA level of COXI in the liver mice of ET group was significant increased(p < 0.05).(6)There was no significant difference in protein expression of LDHA,PCK1,G6 pase,P-AMPK /AMPK in each group.Conclusion:(1)Compared with high intensity interval exercise,moderate intensity endurance exercise reduce the incidence of DEN-induced liver tumors.This indicates that moderate intensity endurance exercise has a better anti-liver tumor effect.(2)High intensity interval exercise significantly increased the lactate content in serum of mice,indicating that higher concentrations of static lactate are not conducive to the anti-tumor effect of exercise.(3)Both moderate intensity endurance exercise and high intensity interval exercise can reduce the gene expression of LDH subunits,suggesting that the LDH subunits play a role in exercise anti-tumor.(4)Moderate intensity endurance exercise increase the expression of mitochondrial respiratory chain complex subunit gene,possibly improve the function of mitochondrial respiratory chain,inhibit the aerobic glycolysis of liver tumor cells,and thus reduce the incidence of liver tumor.Significance: This aim of this study was to compare the anti-cancer effects of moderate intensity endurance exercise and high intensity interval exercise and its mechanism.Taking the lactate metabolism pathway as the breakthrough point.It was found that endurance exercise reduce the cancer incidence compared with high intensity interval exercise.It was also preliminarily revealed that the mechanism of moderate intensity endurance exercise to reduce liver tumorigenesis may be related to the increase of mitochondrial respiratory chain function.The results of the study will provide theoretical support for the selection of a reasonable exercise regimen for antitumor.