MALAT1通过竞争miR-124上调SMYD3并促进乳腺癌细胞增殖与迁移

MALAT1 upregulates SMYD3 by competition with miR-124 and promotes proliferation and migration of breast cancer cells

为了探究lncRNA MALAT1是否会通过与组蛋白甲基化酶SMYD3间的相互调控对乳腺癌细胞的增殖和迁移产生影响,采用siRNA敲低MCF-7、MDA-MB-231乳腺癌细胞中的内源性MALAT1后,然后应用划痕和MTT法检测细胞迁移和增殖情况;实时定量PCR(RealtimePCR)、免疫蛋白印迹(Westernblot)等方法检测si-MALAT1对miRNA-124、SMYD3及其下游基因mRNA及蛋白质水平的影响。结果显示:siRNA靶向敲低MALAT1后可降低乳腺癌细胞的迁移和增殖速度,同时抑制SMYD3及其下游靶基因N-cadherin、MYL9、MMP9、CYR61等的转录表达,并上调miR-124。miR-124的过表达可降低SMYD3在乳腺癌细胞中的表达,且MALAT1的敲低可以缓解miR-124抑制剂对SMYD3蛋白质水平表达的促进作用。此外,转染外源质粒使SMYD3过表达可激活MALAT1转录,反之siRNA干扰SMYD3后则会下调MALAT1。研究结果表明:lncRNAMALAT1可以作为miR-124的ceRNA调控SMYD3,同时SMYD3可反馈性激活MALAT1的转录,这一相互调控作用将影响到乳腺癌细胞的增殖与迁移能力。

To investigate whether lncRNA MALAT1 affects the migration and proliferation of breast cancer cells through the regulation with histone methyltransferase SMYD3,the endogenous MALAT1 in the MCF-7 and MDA-MB-231 breast cancer cells were knocked down by siRNA,and then the migration and proliferation of cells were detected by wound healing migration and MTT assay.The effects of si-MALAT1 on the mRNA and protein levels of miRNA-124,SMYD3 and its downstream genes were detected by Real time PCR and Western blot.The results showed that siRNA-targeted knockdown of MALAT1 reduced the migration and proliferation of breast cancer cells,and inhibited the transcriptional expression of SMYD3 and its downstream genes,including N-cadherin,MYL9,MMP9 and CYR61,and up-regulated miR-124.Overexpression of miR-124 reduced the expression of SMYD3 in breast cancer cells,and knockdown of MALAT1 attenuated the promotion of SMYD3 protein expression by miR-124 inhibitors.In addition,SMYD3 overexpression activated MALAT1 transcription,whereas siRNA interference with SMYD3 downregulated MALAT1.These results indicate that LncRNA MALAT1 acted as a competing endogenous RNA (ceRNA) of miR-124 to regulate expression of SMYD3 in breast cancer cells,and SMYD3 can activate the transcription of MALAT1,which will affect the proliferation and migration of breast cancer cells.