谷氨酰胺对过氧化氢诱导氧化应激人结肠癌HT-29细胞损伤和凋亡的影响

本试验旨在通过研究谷氨酰胺对过氧化氢(H_2O_2)诱导氧化应激人结肠癌HT-29细胞损伤和凋亡的影响,阐明谷氨酰胺的抗氧化效果和作用机理。HT-29细胞经不同浓度0(对照组)、0.5、2.0、10.0 mmol/L]谷氨酰胺和0.35 mmol/L H_2O_2分别处理12、24、32 h后,测定细胞的超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,并采用荧光定量PCR方法分析谷氨酰胺对H_2O_2诱导的细胞凋亡相关基因的mRNA相对表达量,以及采用膜联蛋白V-异硫氰酸荧光素/碘化丙啶双染法对HT-29细胞染色,并用流式细胞仪检测细胞的凋亡情况。结果表明:1)处理24 h后,0.5、2.0 mmol/L Gln组SOD活性显著高于对照组(P0.05);处理32 h后,0.5、2.0 mmol/L Gln组SOD活性显著高于对照组(P0.05),MDA含量显著低于对照组(P0.05)。2)处理12 h后,各组天冬氨酸蛋白水解酶-3(Caspase-3)和B淋巴细胞瘤-2相关X蛋白(Bax)mRNA相对表达量无显著差异(P0.05)。与对照组比较,0.5 mmol/L Gln组核转录因子κB(NF-κB)mRNA相对表达量显著降低(P0.05),0.5与2.0 mmol/L Gln组B淋巴细胞瘤-2(Bcl-2)mRNA相对表达量显著提高(P0.05)。处理24 h后,与对照组比较,0.5、2.0和10.0 mmol/L Gln组Caspase-3、NF-κB和Bax mRNA相对表达量均显著降低(P0.05),Bcl-2mRNA相对表达量显著升高(P0.05)。处理32 h后,与对照组比较,2.0 mmol/L Gln组细胞表面诱导凋亡分子(FAS)、Caspase-3、NF-κB、Bax mRNA相对表达量均显著降低(P0.05),Bcl-2mRNA相对表达量显著升高(P0.05);10.0 mmol/L Gln组FAS、Caspase-3、NF-κB、Bax mRNA相对表达量均显著升高(P0.05)。3)处理24 h后,与对照组比较,Gln处理使活细胞数量提高了5.32%~11.97%,坏死细胞数量降低了6.75%~12.66%。处理32 h后,与对照组比较,Gln处理使活细胞数量提高了1.39%~7.63%,坏死细胞数量降低了3.40%~4.57%。由此可见,谷氨酰胺可抑制氧化应激反应,降低H_2O_2诱导的HT-29细胞凋亡。

Effects of Glutamine on Oxidative Damage and Apoptosis of Human Enterocyte-Like HT-29 Cells Induced by Hydrogen Peroxide

This experiment was conducted to study effects of glutamine ( Gln) on oxidative damage and apop-tosis of human enterocyte-like HT-29 cells induced by hydrogen peroxide (H2O2), and to explore the antioxi-dant function of Gln and its mechanisms. HT-29 cells I were induced by different concentrations 0 ( control group), 0.5, 2.0 and 10.0 mmol/L] Gln and 0.35 mmol/L H2O2 for 12, 24 and 32 h, the superoxide dis-mutase ( SOD) activity and malondialdehyde ( MDA) content in cells were measured, and the mRNA relative expression of related to cell apoptosis gene were also assessed by RT-qPCR. Furthermore, the HT-29 cells were dyed with the Annexin V-FITC/PI double staining method, and the apoptosis of cells was determined by the flow cytometer. The results showed as follows:1) after treated 24 h, the SOD activity in 0.5 and 2.0 mmol/L Gln groups was significantly higher than that in control group ( P<0.05); after treated 32 h, the SOD activity in 0.5 and 2.0 mmol/L Gln groups was significantly higher than that in control group (P<0.05), and the MDA content was significantly lower than that in control group ( P<0.05) . 2) After treated 12 h, there were no significant differences on the mRNA relative expressions of cysteinyl aspartate specific proteinase-3 (Caspase-3) and B cell lymphoma/leukemia-2 associated X protein (Bax) among all groups (P>0.05). Compared with the control group, the mRNA relative expression of nuclear factor kappa B ( NF-κB ) in 0.5 mmol/L Gln group was significantly decreased (P<0.05), the mRNA relative expression of B cell lym-phoma/leukemia-2 (Bcl-2) in 0.5 and 2.0 mmol/L Gln groups was significantly increased (P<0.05). After treated 24 h, compared with the control group, the mRNA relative expressions of Caspase-3, NF-κB and Bax in 0.5, 2.0 and 10.0 mmol/L Gln groups were significantly decreased (P<0.05), while the mRNA relative expression of Bcl-2 was significantly increased ( P<0. 05 ) . After treated 32 h, compared with the control group, the mRNA relative expressions of FAS, Caspase-3, NF-κB and Bax in 2.0 mmol/L Gln group were significantly decreased (P<0.05), while the mRNA relative expression of Bcl-2 was significantly increased (P<0.05); the mRNA relative expressions of FAS, Caspase-3, NF-κB and Bax in 10.0 mmol/L Gln group were significantly decreased (P<0.05). 3) After treated 24 h, compared with the control group, the living cells number in Gln groups increased by 5.32% to 11.97%, and the necrotic cells number decreased by 6.75%to 12.66%. After treated 32 h, compared with the control group, the living cells number in Gln groups in-creased by 1.39% to 7.63%, and the necrotic cells number decreased by 3.40% to 4.57%. It is concluded that glutamine can restrain the oxidant damage of HT-29 induced by H2O2 and decrease the cells apoptosis.