脂联素抑制糖尿病小鼠结直肠癌生长转移及机制研究

Adiponectin inhibits growth and metastasis of colorectal cancer in diabetic mice and its mechanism

目的研究脂联素对糖尿病小鼠结直肠癌的作用及其作用靶点和分子机制。方法通过注射MCA38细胞构建结直肠癌皮下成瘤、肝转移模型。将32只糖尿病小鼠分为皮下成瘤治疗(SA)组、皮下成瘤对照(SC)组、肝转移治疗(LA)组和肝转移对照(LC)组,每组8只。SA组、LA组注射小鼠重组脂联素,SC组、LC组注射0.9%氯化钠注射液,定期测量瘤体积、血糖浓度;处死前采集血液及肿瘤组织标本;计数转移性结节数,并在光镜下观察肿瘤组织,采用ELISA法检测血清中糖尿病相关指标脂联素(ADPN)、瘦素(Leptin)、胰岛素样生长因子-1(IGF-1)、胰岛素(Insulin)和炎症相关指标肿瘤坏死因子-α(TNF-α)、IL-6、IL-1β浓度;采用Western blot法测定肿瘤组织中相关通路蛋白胰岛素生长因子受体-2(IGF-2R)、Ras、c-Myc、β-catenin、过氧化物酶体增殖剂激活受体抗体γ(PPARγ)及p21活化激酶(PAK-1)表达水平。结果SA组肿瘤体积较SC组小(P<0.05),LA组肝转移性结节数较LC组少(P<0.01),SA组、LA组血糖浓度、Leptin、IGF-1、Insulin、TNF-α、IL-6、IL-1β浓度均较SC组、LC组为低(均P<0.01),ADPN浓度较SC组、LC组为高(P<0.01),相关通路蛋白IGF-2R、Ras、c-Myc、β-catenin、PPARγ及PAK-1表达水平均较SC组、LC组下调(均P<0.05)。肿瘤病理切片显示注射脂联素后肿瘤细胞减少。结论脂联素能够抑制糖尿病小鼠结直肠癌的增殖和转移,可通过改善胰岛素抵抗,抑制炎症相关标志物的表达,其作用与下调肿瘤相关通路蛋白的表达相关。

Objective To investigate the effects of adiponectin on colorectal cancer in treatment of diabetic mice,and to clarify the target and molecular mechanism of adiponectin on tumor inhibition.Methods The models of Subcutaneous tumor and liver metastasis were established by injection cells MCA38.32 diabetic mice were randomly divided into 4 groups with 8 animals in each group.Normal saline were given by intraperitoneal injection into subcutaneous tumor mice(group SC)and liver?metastasis mice(group LC),adiponectin were given by intraperitoneal injection into subcutaneous tumor mice(group SA)and liver?metastasis mice(group LA),respectively.The tumor size and blood glucose concentration were recorded regularly.Blood and tumor tissue samples were obtained before execution.Metastatic nodules were measured,and tumor tissue were examined by HE stain.The concentration of adiponectin,Leptin,insulin-like growth factor(IGF)-1,Insulin,tumor necrosis factor(TNF)-α,interleukin(IL)-6 and IL-1βin serum were determined by ELISA.The expression of tumor-associated pathway proteins IGF-2 R,Ras,c-Myc,β-catenin,PPARγand PAK-1 in tumor tissue were determined by Western blot.Results The sizes of tumors in group SC were decreased than group SC,the numbers of metastatic nodules in group LA were decreased than group LC.The concentration of ADPN were increased,whereas the concentration of Leptin,IGF-1,Insulin,TNF-α,IL-6,IL-1βwere decreased,and the expression of IGF-2 R、Ras、c-Myc、β-catenin、PPARγand PAK-1 were down-regulated in group SA and LA compared with group SC and LC(all P<0.05).Histopathologic showed tumor cells were decreased after adiponectin injection.Conclusion Adiponectin can inhibit the proliferation and metastasis of colorectal cancer cells,which might be associated with the improvement of insulin resistance,down-regulation of inflammatory markers and tumor-associated pathway proteins.