脐带间充质干细胞恶性分化并促进肺癌A549细胞移植瘤生长及转移

HUCMSCs undergo malignant transformation and promote the growth as well as the metastasis of A549 subcutaneous xenografts in nude mice

目的探讨人脐带来源的间充质干细胞(human umbilical cord mesenchymal stem cells,hUCMSCs)对裸鼠肺癌移植瘤生长及转移的影响。方法将24只裸鼠随机分为4组,分别为A549细胞单独注射组(A549组)、hUCMSCs单独注射组(MSCs组)、A549细胞与正常人皮肤成纤维细胞(skin fibroblasts,SKs)共同注射组(A549+SKs组)、hUCMSCs与A549细胞共注射组(A549+MSCs组)。HE染色和免疫组织化学染色确定hUCMSCs注射裸鼠皮下结节性质;流式细胞分选技术分选出各组移植瘤瘤组织中的A549细胞;实时荧光定量PCR和Westernblot检测A549细胞中上皮-间质转化(epithelial-mesenchymal transition,EMT)相关分子标志物的表达差异。结果 hUCMSCs注射后,hUCMSCs发生恶性分化,hUCMSCs与A549细胞共注射后肺癌移植瘤体积明显大于单独A549注射组和A549与SKs共注射组;2只A549与hUCMSCs共注射组裸鼠出现了肺癌肝脏转移,而A549组与A549+SKs组的全部6只裸鼠均没有发现肝脏转移。A549与MSCs共注射组A549细胞中上皮表型特征分子E-cadherin、β-catenin mRNA相对表达量和β-catenin蛋白表达水平高于A549组与A549+SKs组,E-cadherin蛋白表达水平明显高于A549+SKs组,间质表型特征分子N-cadherin和vimentin蛋白表达水平明显低于A549组与A549+SKs组,EMT转录调控因子twist蛋白表达水平低于A549组与A549+SKs组。结论 hUCMSCs可以自我恶性分化;hUCMSCs能促进肺癌A549细胞移植瘤的生长与转移;hUCMSCs增强A549细胞侵袭、转移的机制不是通过诱导A549细胞发生EMT(上皮-间质转化)。

Objective The present study aimed to investigate the effect of human umbilical cord-derived mesenchymal stemcells(hUCMSCs)on lung cancer xenograft growth and metastasis in nude mice.Methods Twenty-four nude mice were randomly dividedinto four groups:A549cells injection alone(group A549),hUCMSCs injection alone(group MSCs),A549cells co-injection withnormal human skin fibroblasts(group A549and SKs),A549cells co-injection with hUCMSCs(group A549and MSCs).HE stainingand immunohistochemistry were used to characterize subcutaneous nodules in group MSCs.A549cells from tumor tissues were sortedout by flow cytometry.The expression of epithelial-mesenchymal transition(EMT)molecular markers in A549cells was evaluatedby quantitative real-time PCR and Western-blotting.Results HUCMSCs undergo spontaneous malignant transformation after beinginjected into nude mice.The volume of transplanted tumor in group A549and MSCs was significantly higher than that in group A549as well as group A549and SKs.While two nude mice in group A549and MSCs had liver metastases,none was observed in groupA549or group A549and SKs.The expression of E-cadherin,β-catenin at mRNA level andβ-catenin at protein level were significantly higher in group A549and MSCs than in group A549and group A549and SKs.The expression levels of N-cadherin,vimentin and EMTtranscription factor Twist were significantly lower in group A549and MSCs than in group A549and group A549and SKs.ConclusionHUCMSCs undergo spontaneous malignant transformation and promote the growth as well as the metastasis of subcutaneous xenograftsin nude mice,the mechanism of which is unlikely through inducing EMT in A549cells.