title: MicroRNA-21 targets tumor suppressor genes in invasion and metastasis.
abstract: MicroRNAs (miRNAs) are a class of naturally occurring small non-coding RNAs that target protein-coding mRNAs at the post-transcriptional level. Our previous studies suggest that mir-21 functions as an oncogene and has a role in tumorigenesis, in part through regulation of the tumor suppressor gene tropomyosin 1 (TPM1). Given that TPM1 has been implicated in cell migration, in this study we further investigated the role of mir-21 in cell invasion and tumor metastasis. We found that suppression of mir-21 in metastatic breast cancer MDA-MB-231 cells significantly reduced invasion and lung metastasis. Consistent with this, ectopic expression of TPM1 remarkably reduced cell invasion. Furthermore, we identified two additional direct mir-21 targets, programmed cell death 4 (PDCD4) and maspin, both of which have been implicated in invasion and metastasis. Like TPM1, PDCD4 and maspin also reduced invasiveness of MDA-MB-231 cells. Finally, the expression of PDCD4 and maspin inversely correlated with mir-21 expression in human breast tumor specimens, indicating the potential regulation of PDCD4 and maspin by mir-21 in these tumors. Taken together, the results suggest that, as an oncogenic miRNA, mir-21 has a role not only in tumor growth but also in invasion and tumor metastasis by targeting multiple tumor/metastasis suppressor genes. Therefore, suppression of mir-21 may provide a novel approach for the treatment of advanced cancers.
authors.affiliation: Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, 825 N. Rutledge, PO Box 19626, Springfield, IL 62794, USA.
authors.forename: Shuomin
authors.initials: S
authors.lastname: Zhu
authors.forename: Hailong
authors.initials: H
authors.lastname: Wu
authors.forename: Fangting
authors.initials: F
authors.lastname: Wu
authors.forename: Daotai
authors.initials: D
authors.lastname: Nie
authors.forename: Shijie
authors.initials: S
authors.lastname: Sheng
authors.forename: Yin-Yuan
authors.initials: YY
authors.lastname: Mo
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000556:secondary; D008297:Male; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009857:Oncogenes; D012333:RNA, Messenger / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D015843:Serpins / Q000096:biosynthesis / Q000235:genetics; D014335:Tropomyosin / Q000096:biosynthesis / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; C114487:PDCD4 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C085344:SERPIN-B5; D015843:Serpins; C490775:TPM1 protein, human; D014335:Tropomyosin; D025521:Tumor Suppressor Proteins