解偶联蛋白2在结肠肿瘤发生发展中的作用研究

The role of uncoupling protein 2 in occurrence and development of colon tumor

目的 探讨解偶联蛋白2（UCP2）在结肠肿瘤发生、发展中的作用.方法 免疫组织化学检测UCP2在正常结肠组织、增生性息肉、绒毛管状腺瘤、结肠癌中的表达阳性率.雄性UCP2-/-鼠及UCP2＋/＋鼠各12只（模型组）均腹腔注射氧化偶氮甲烷（AOM）造模,UCP2-/-鼠及UCP2＋/＋鼠各6只均腹腔注射0.9％ NaCl溶液作为对照.Western印迹法检测鼠肠肿瘤组织中增殖核抗原Ki67、细胞增殖相关基因[细胞外信号调节激酶（ERK） 1/2、磷酸化ERK1/2（ pERK1/2）、Jun氨基末端激酶（JNK） 1/2、磷酸化JNK1/2（ pJNK1/2）]及鼠脾组织中诱导型一氧化氮合酶（iNOS）表达水平.使用脂质氧化丙二醛（MDA）试剂盒检测鼠近端结肠肿瘤组织中MDA的含量.结果 UCP2在人正常结肠黏膜组织中几乎无表达,在结肠腺瘤和结肠增生性息肉组织中的阳性率分别为11/20和2/10,在结肠癌组织中则为85.9％（67/78）.UCP2-/-鼠成瘤数量[（1.4±0.5）个]少于UCP2＋/＋鼠[（2.5±0.8）个,t=3.351,P=0.005].UCP2-/-鼠近端结肠肿瘤最大径[（1.5±0.7）cm]大于UCP2＋/＋鼠[（0.9±0.4） cm,t=2.650,P=0.021].UCP2-/-鼠近端结肠Ki-67蛋白表达水平（1.30±0.01）高于UCP2＋/＋鼠（0.80±0.09,t=2.895,P=0.015）.UCP2-/-鼠近端结肠肿瘤组织中pERK1/2、pJNK1/2表达水平（分别为1.16±0.12和1.67±0.06）高于UCP2＋/＋鼠（分别为0.37±0.08和1.07±0.17,t值分别=2.821和2.201,P值分别=0.016和0.043）.UCP2-/-鼠近端结肠肿瘤组织中MDA含量[（26.91±2.02） nmol/mg]高于UCP2＋/＋鼠[（15.58±1.42）nmol/mg,t=3.735,P=0.002].UCP2-/-鼠脾脏组织中iNOS表达水平（0.78±0.07）高于UCP2＋/＋鼠（0.48±0.06,t=2.212,P=0.043）.结论 UCP2通过调控活性氧自由基（ROS）产生而参与结肠肿瘤的发生、发展,该过程可能与ROS激活ERK1/2及JNK1/2从而导致肠上皮细胞过度增殖有关.

Objective To explore the role of uncoupling protein 2 （UCP2） in occurrence and development of colon tumor.Methods The positive expression rates of UCP2 in normal colon tissue,hyperplastic polyps,tubular villous adenoma and colon caner were detected by immunohistochemical analysis.Azoxymethane （AOM） was given in male UCP2-/- mice and UCP2＋/＋ mice to induce model.The expressions of proliferating cell nuclear antigen Ki-67,cell proliferation-related genes （extracellular signal-regulated kinase （ERK） 1/2,phosphorylated extracellular signal-regulated kinase （pERK1/2）,Jun N-terminal kinase（JNK） 1/2 and phosphorylated c-Jun N-terminal kinase（pJNK1/2）in mice colon tumor tissues and inductible nitric oxide synthase（iNOS）in spleen tissue were detected by Western blot.The content of malondialdehyde（MDA）in proximal colon tumor tissue was determined with MDA kit.Results There was no expression of UCP2 in normal colon mucosa tissue,however the positive ratio in colon adenoma and hyperplastic polyps was 11/20 and 2/10 respectively,and the positive percentage in colon caner was 85.9% （67/78）.The number of colon tumor formation in UCP2-/- mice （1.4±0.5）was less than that of UCP2＋/＋ mice （2.5±0.8,t=3.351,P=0.005）.The maximum diameter of proximal colon tumor in UCP2 mice （1.5±0.7cm） was greater than that of UCP2＋/＋ mice [（0.9±0.4） cm,t=2.650,P=0.021].The expression of Ki-67 in the UCP2-/ - mice proximal colon （1.30±0.01）was higher than that in UCP2＋/＋ mice （0.80±0.09,t=2.895,P=0.015）.The expression of pERK1/2 and pJNK1/2 in UCP2-/- mice proximal colon tumors （1.16±0.12 and 1.67±0.06） was higher than that in UCP2＋/＋ mice （0.37±0.08 and 1.07±0.17,t=2.821 and 2.201,P =0.016 and 0.043）.The MDA content in UCP2-/- mice proximal colon tumor tissue [（26.91 ± 2.02） nmol/mg] was higher than that in UCP2＋/ ＋ mice [（15.58 ±1.42） nmol/mg,t=3.735,P=0.002].iNOS expression in UCP2- /- mice （0.782±0.07） spleen was higher than that in UCP2＋/＋ mice （0.48±0.06,t=2.212,P=0.043）.Conclusions UCP2 involved in tumor occurrence and development through ROS regulation.This process may be related to ROS activating ERK and JNK1 then result in intestinal epithelium excessive proliferation.