替莫唑胺联合干扰素α/β治疗胶质瘤移植瘤的实验研究

IFN-α/β Enhance Temozolomide Cytotoxic Activity Against Human Glioma in vivo

背景与目的:6-氧甲基鸟嘌呤-DNA甲基转移酶(O6-methylguanine-DNA-methyl transferase,MGMT)是肿瘤对甲基化类药物耐药的重要原因之一。替莫唑胺(temozolomide,TMZ)常规方案对MGMT阳性胶质瘤的化疗效果不理想。本实验在动物体内观察干扰素α/β(interferonα/β,IFNα/β)联合替莫唑胺对MGMT阳性胶质瘤的治疗作用,并进一步探讨了IFNα/β对MGMT、核因子NF-κB(nuclear factor kappa B,NF-κB)表达的影响。方法:建立MGMT阳性胶质瘤干细胞SKMG-4G、U251G裸鼠皮下移植瘤模型,成瘤后将裸鼠随机分为空白对照组、TMZ组、IFNα组、IFNβ组、TMZ+IFNα组和TMZ+IFNβ组,每组各5只荷瘤鼠,成瘤后7天分别给予药物治疗,观察动物体重、肿瘤的生长情况;同时采用免疫组织化学法及蛋白免疫印记法检测瘤组织中MGMT蛋白和NF-κB蛋白的表达。结果:药物处理对动物体重没有明显的影响。TMZ组、IFNα组、IFNβ组、TMZ+IFNα组和TMZ+IFNβ组肿瘤生长均低于空白对照组,差异有统计学意义(P﹤0.05)。TMZ对SKMG-4G、U251G移植瘤的抑瘤率分别为35.2%±2.28%、16.7%±1.96%。当TMZ与IFNα或IFNβ联合应用时,能够更为显著地抑制肿瘤的生长,TMZ+IFNα组和TMZ+IFNβ组对SKMG-4G移植瘤的抑瘤率分别为58.4%±4.34%和63.4%±1.08%,对U251G移植瘤的抑瘤率分别为41.1%±8.66%和44.5%±1.90%,与相应的单独用药组比较,差异存在统计学意义(P﹤0.05)。TMZ+IFNα组和TMZ+IFNβ组的MGMT、NF-κB蛋白表达明显低于TMZ组,且MGMT与NF-κB表达呈正相关。结论:IFNα/β联合TMZ有协同的抗肿瘤作用,其机制可能与干扰素α/β下调胶质瘤内NF-κB继而下调MGMT的表达相关。

BACKGROUND OBJECTIVE： DNA repair gene,O6-methylguanine-DNA methyltransferase（MGMT） is one of the important causes committed alkylating agent resistance in human cancers.Temozolomide（TMZ）,an alkylating agent,has become the first-line chemotherapy for malignant gliomas but usually the results were unsatisfactory for MGMT positive gliomas.The aim of the present study was to evaluate the efficacy and mechanism of TMZ combined with IFNα/β in MGMT-positive glioma xenografts.METHODS： Xenograft models with subcutaneous implantation of MGMT-positive glioma stem cells（GSCs）,SKMG-4G and U251G,were treated with TMZ,IFNα or IFNβ alone,or TMZ in combination with IFNα/β,respectively.The expression of MGMT as well as nuclear factor kappa B（NF-κB）proteins correlated withTMZ resistance was detected by immunohistochemistry and Western blot analysis.RESULTS：There were no body weight change in all treated mice.All the treatments were significantly inhibited tumor growth as compared with sham group（Ρ0.05）.The tumor growth inhibit rate（IR）of TMZ to SKMG-4G and U251G was 35.2%±2.28%and 16.7%±1.96%,respectively.When TMZ combined with IFNαor IFNβ,the IR to SKMG-4G was 58.4%±4.34%and 63.4%±1.08%;while to U251G,it was 41.1%±8.66%and 44.5%±1.90%,respectively（Ρ0.05）.IFNα/βalso significantly decreased the expression levels of NF-κB and MGMT in the glioma samples.In addition,the expression of MGMT positively correlated with that of NF-κB in the glioma tissues.CONCLUSION：IFNα/βenhance the anticancer effect of TMZ in gliomas,which could be through down-regulating NF-κB as well as MGMT expression.