ABSTRACT
Objective High mobility group box-1 protein ( HMGB1) plays an essential role in regulating energy metabolism of tumor cells via affecting mitochondrial autophagy .The aim of this study was to explore the effect of HMGB 1 on mitochondrial biogene-sis and cell energy metabolism in anoxia environment . Methods HepG2 cells were divided into normoxia control group ( cells were cultured in a culture box containing 5%CO2) , hypoxia control group ( cells were cultured in a culture box containing 1%O2+5%CO2+94%N2 ) , hypoxia HMGB1 siRNA group ( cells were cultured in a culture box containing 1% O2+5% CO2+94% N2 after transfected with HMGB1 siRNA) and hypoxia NC siRNA group ( cells were cultured in a culture box containing 1%O2+5%CO2+94%N2 after trans-fected with negative control siRNA ) .MTS assay was carried out to measure cell proliferation rate .The alterations of mitochondrial bio-genesis associated proteins were detected by RT-PCR and western blot.Mitochondrial density and morphology were determined by transmission electron microscopy (TEM).The ATP content in whole cell extracts was determined with a colorimetric ATP detection kit . Results Compared with the hypoxia control and hypoxia NC siR-NA group, the proliferationof hypoxia HMGB1 siRNA group was significantly inhibited, especially in 48 h and 72 h(P<0.05).Com-pared with hypoxia control group and hypoxia NC siRNA group , the expression of PGC 1α, NRF1and TFAM in hypoxia HMGB1 siRNA group were decreased significantly ( P<0.05) .Western blot results showed that , compared with normoxia control group , the expressions of PGC1α(0.494±0.210 vs 0.090±0.020), NRF1(1.080±0.470 vs 0.581±0.190)and TFAM(1.585±0.340 vs 0.792±0.350) protein in hypoxia 24 h group were increased obviously ( P<0.05) .Compared with hypoxia control group and hypoxia NC siRNA group , the expres-sions of PGC 1α, NRF1 and TFAM protein in hypoxia HMGB1 siRNA group were significantly decreased (P<0.05).Compared with hypoxia control group , the content of ATP in the HMGB 1 siRNA hypoxia group was significantly decreased , and hypoxia 12 h and 24 h were the most obvious ( P<0.05) . Conclusion HMGB1 could maintain cell energy metabolism by regulating mitochondrial biogene-sis so that cells could continue to proliferate in adverse anoxia environment .
ABSTRACT
AIM:To investigate the expression of microRNA-141 (miR-141) in human hepatocellular carcino-ma (HCC) cell line SMMC-7721 and normal hepatocyte line HL-7702, and to analyze the effect of abnormal expression of miR-141 on the malignant biological behaviors of human hepatocarcinoma cells.METHODS:The RNA from SMMC-7721 cells and HL-7702 cells was extracted.SYBR Green real-time PCR was performed to detect the expression of miR-141. Synthetic miR-141 mimic and its negative control were transfected into the SMMC-7721 cells, and miR-141 inhibitor and its negative control were transfected into the HL-7702 cells by the method of Lipofectamine.After transfection, MTS assay and BrdU-ELISA were employed to evaluate the effect of miR-141 on the cell proliferation.Flow cytometry was used to detect cell cycle and apoptosis.The changes of migration ability were investigated by Transwell invasion assay.RESULTS:The expression of miR-141 in the SMMC-7721 cells was significantly lower than that in the HL-7702 cells ( P<0.05 ) .Com-pared with blank group, Lipofectamine group and negative control group, the proliferation of the SMMC-7721 cells trans-fected with 25 nmol/L miR-141 mimic was significantly inhibited in a time-dependent manner (P<0.05).The percenta-ges of G1 phase cells and early apoptotic rate were significantly increased when miR-141 was up-regulated, but the migra-tion ability was inhibited (P<0.05).Compared with blank group, Lipofectamine group and negative control group, the proliferation of HL-7702 cells transfected with 50 nmol/L miR-141 inhibitor was significantly increased in a time-dependent manner (P<0.05).When miR-141 was down-regulated, the percentages of G1 phase cells and early apoptotic rate were significantly decreased, but the migration ability was enhanced (P<0.05).CONCLUSION:miR-141 is down-regulated in human hepatocarcinoma cell line.Up-regulation of miR-141 will not only inhibit cell proliferation and migration ability, but also affect the cell cycle and apoptosis of SMMC-7721 cells.miR-141 may function as a tumor suppressor gene during HCC development.