The Mechanism Of Ras Oncogene Induced Mitochondrial Dysfunction In The Development Of Hepatic Tumor

Objective: To investigate the mechanisms of Ras oncogene induced mitochondrial dysfunction in the development of hepatic tumor.Methords: 1.The hepatic tumor tissues and tumor adjacent tissues of H-ras12 V transgenic mice and hepatic tissues of normal mice were collected.The activity of mitochondrial respiratory chain complex I was measured by quantitative colorimetric detection kit.The m RNA expression levels of Bcl-2,Ucp2,and key enzymes of mitochondrial respiratory chain complexes were detected by transcriptome sequencing and RT-q PCR.The ROS levels were detected by high quality oxidative stress ROS fluorescence assay kit.2.ERK inhibitor AZD6244 were used to inhibit transgenic male mice,and the effects of inhibition of ERK on mitochondrial function were detected.Results: 1.Compared to the hepatic tissues of normal mice,in hepatic tumor tissues and tumor adjacent tissues of transgenic mice,the activity of mitochondrial respiratory chain complex I was significantly reduced(F=14.26,P=0.003)and the m RNA expression levels of key enzymes of mitochondrial respiratory chain complex I/III/IV(Ndufa12,Ndufs6,Uqcrb,Cox7a2)were significantly decreased(F=18.55,P=0.001;F=7.06,P=0.014;F=12.81,P=0.002;F=10.51,P=0.004 respectively).Compared to the hepatic tissues of normal mice and hepatic tumor tissues,the ROS levels in tumor adjacent tissues were significantly increased,F=31.35,P=0.001.Compared to the hepatic tissuesof normal mice and tumor adjacent tissues,the m RN A levels of Bcl-2 and Ucp2 in tumor adjacent tissues were significantly increased(F=20.29,P=0.002;F=15.51,P=0.001 respectively).2.Inhibition experiments showed that,in tumor adjacent tissues of transgenic mice,after using AZD6244,the levels of p-ERK was significantly reduced when compared with the control group(F=42.99,P=0.022);in hepatic tumor tissues of transgenic mice,after using AZD6244,the levels of p-ERK was significantly reduced when compared with the control group(F=43.34,P=0.002).in tumor adjacent tissues of transgenic mice,after using AZD6244,the m RN A expression levels of key enzymes of mitochondrial respiratory chain complex I/III/IV(Ndufa12,Uqcrb,Cox7a2)were significantly increased when compared with the control group(F=4.05,P=0.084;F=11.25,P=0.015;F=31.007,P=0.001);in hepatic tumor tissues of transgenic mice,after using AZD6244,the m RNA expression levels of key enzymes of mitochondrial respiratory chain complex I/III/IV(Ndufa12,Uqcrb,Cox7a2)were significantly increased when compared with the control group(F=5.81,P=0.042;F=5.79,P=0.043;F=15.17,P=0.008).Conclusion: Ras oncogene may through the ERK signaling pathway directly reduces the transcriptional levels of the key enzymes of mitochondrial resp iratory chain complexes in hepatocytes which lead to mitochondrial dysfunction and high intracellular ROS levels.In hepatic tumor cells,the elevated expression levels of Bcl-2 and Ucp2 contribute to the reduction of mitochondrial ROS levels and the promotion of tumorigenesis and development.