Effects of ER Stress and PUMA on 5-FU-induced Liver Cell Injury and Apoptosis / 中山大学学报(医学科学版)

ABSTRACT

@#【Objective】To investigate the role of ER stress and PUMA in 5-FU-induced liver cells injury and apoptosis.【Methods】We established 5-FU-induced liver injury models by intraperitoneally injecting the isodose 5-FU to 10 PUMA knockout mice(PUMA-KO)and 20 PUMA Wild type mice(PUMA-WT). Meanwhile,10 WT mice were intraperitoneally injected with 4-Phenylbutyric acid,the ER stress inhibitor. In the control group,10 KO mice and 20 WT mice were given the same amount of normal saline.After the modeling,serum and liver tissues of the mice were collected to assess the degree of liver pathological injury,measure the expression levels of ALT and AST in serum,and detect the expression levels of PUMA and GRP78 in liver tissues. The changes of these indicators in different treatment groups were observed and compared.【Results】Compared with the WT control group,serum ALT and AST levels were significantly increased in the 5-FU group,H&E staining showed punctate focal necrosis,accompanied by hemorrhage and inflammation. TUNEL staining showed apoptotic cells were markedly added(Z = 3.78,P < 0.001),and expressions of PUMA and GRP78 were obviously augmented,suggesting that both PUMA and ER stress were involved in 5-FU-induced liver cells injury and apoptosis. Then,in the 4-PBA group,we found that the expression levels of GRP78 and PUMA were down-regulated,and apoptosis of liver cells was reduced under the same dose of 5-FU(χ~2= 32.99,Z = 3.78,P <0.001),further confirming that both PUMA and ER stress were involved in this process. Subsequently,it was found that,when induced by the same dose of 5-FU,cleaved caspase-3 staining showed that the liver apoptosis signal of the PUMA knockout mice was lower than the WT mice(χ~2= 33.99,Z = 3.78,P < 0.001),but the difference in the expression of GRP78 between the two groups was not statistically significant. In summary,the expression of PUMA was reduced and the apoptosis of liver cells was attenuated after the inhibition of ER stress;PUMA knockdown could not influence the activation of ER stress but alleviated apoptosis of liver cells.【Conclusions】PUMA mediates ER stress-up-regulated liver cells apoptosis in 5-FU-induced Chemotherapeutic liver injury.