miR-125靶向SMAD4抑制脂多糖诱导的人结肠上皮细胞向肿瘤细胞转化

miR-125 attenuates LPS-induced transition of colorectal epithelial cells into cancer cells through targeting SMAD4

目的观察脂多糖(LPS)对正常结肠上皮细胞向肿瘤细胞转化的影响,探索miR-125和SMAD4在细胞转化过程中的作用和机制。方法以人正常结肠上皮细胞系HCoEpiCs为研究对象,用CCK-8法探索LPS的最佳刺激浓度;用LPS连续刺激HCoEpiCs细胞40代并检测细胞周期相关基因cyclinD1、癌基因c-myc、抗凋亡基因Bcl-2、miR-125和TGF-β信号通路下游效应分子SMAD4的表达,平板克隆和软琼脂集落实验形成情况以确定细胞恶转情况;观察转染miR-125 mimic和inhibitor后SMAD4的表达,通过双荧光素酶基因报告实验验证miR-125和SMAD4的靶向关系。结果LPS刺激浓度为10μg/mL时细胞活力开始出现明显抑制(P<0.05)。以该浓度连续刺激40代后HCoEpiCs细胞cyclinD1、c-myc和Bcl-2均出现显著增高(P<0.05),并出现明显的细胞克隆形成现象。发生转化的细胞中miR-125出现明显的升高(P<0.05),而SMAD4出现显著的降低(P<0.05)。过表达miR-125后,SMAD4和c-myc的表达均出现明显的降低(P<0.05),SMAD4的野生型3′-UTR相对荧光素酶活性出现了明显的下降;而SMAD4的3′-UTR区被突变后,相对荧光素酶活性未出现明显的改变。结论miR-125可靶向SMAD4抑制LPS诱导的结肠上皮细胞HCoEpiCs向肿瘤细胞转化。

Objective To investigate potential roles of miR-125 and SMAD4 in lipopolysaccharide(LPS)-induced colorectal epithelial cells transformed to cancer cells.Methods Cell viability of HCoEpiCs cells exposed to LPS for 24 h was evaluated by CCK-8 assay.CyclinD1,c-myc,Bcl-2,miR-125,and SMAD4 were measured by q-PCR in LPS-induced colorectal epithelial cells malignant transformation.Plane cloning and soft agar colony formation assay were used to identify the result of malignant transformation.Synthetic miR-125 mimic and inhibitor were used to mediate the expression of miR-125 in the 40th passage of LPS-induced HCoEpiCs cells.The activity of miR-125 in the region of SMAD43′-UTR was detected by the double luciferase gene report.Results Cell viability was signifi-cantly repressed by 10μg/mL LPS.The expression of miR-125 was increased in the 40th passage of LPS-induced HCoEpiCs cells,but the level of SMAD4 was down-regulated.The level of SMAD4 and c-myc were decreased when miR-125 was over-expressed in HCoEpiCs cells.Meanwhile,compared to the control group,the activity of SMAD43′-UTR-wild was repressed by miR-125 mimic,but no significant change was observed in the 3′-UTR-mut cells.Conclusions LPS-induced colorectal epithelial cells might be inhibited to transform to cancer cells through miR-125 binding to SMAD4.