title: microRNA-133a regulates the cell cycle and proliferation of breast cancer cells by targeting epidermal growth factor receptor through the EGFR/Akt signaling pathway.
abstract: microRNAs are small, highly conserved, non-coding RNAs that regulate gene expression of target mRNAs through cleavage or translational inhibition, and are widely involved in carcinogenesis and cancer development. In this study, the expression profile of microRNA-133a (miR-133a) was examined in breast cancer cells and breast cancer tissues. The results showed that expression of miR-133a in both breast cancer cells and breast cancer tissues was significantly down-regulated. Over-expression of miR-133a in tumor cells arrested the cell cycle by drastically decreasing the G2 /S phase and retarded the newly synthesized DNA, suggesting a regulatory role for miR-133a in proliferation of breast cancer cells. Bioinformatics prediction showed that epidermal growth factor receptor (EGFR) is a potential target for miR-133a. A dual luciferase reporter gene assay showed that miR-133a bound to the 3' UTR of EGFR but not a mutated 3' UTR, thereby down-regulating the protein expression level. Accordingly, we found that expression of EGFR protein decreased with increased expression of miR-133a in MCF-7 and MDA-MB-231 cells. Over-expression of miR-133a in breast cancer cells resulted in suppression of the level of phosphorylated Akt protein (p-Akt) and inhibition of p-Akt nuclear translocation. These results demonstrate that miR-133a, which may act as a tumor suppressor in breast cancer, regulates the cell cycle and proliferation in tumorigenesis by targeting EGFR through the downstream signal molecule Akt. Overall, these results show that miR-133a may be used as biomarker and/or therapeutic target for diagnosis and therapy of breast cancer.
authors.affiliation: Key Laboratory of Industrial Biotechnology (Ministry of Education), School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Cui
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Changliang
authors.initials: C
authors.lastname: Shan
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: Zhemin
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D020413:3' Untranslated Regions; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D015536:Down-Regulation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D042361:Mammary Glands, Human / Q000378:metabolism / Q000473:pathology; D035683:MicroRNAs / Q000378:metabolism*; D009154:Mutation; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D020413:3' Untranslated Regions; C548234:MIRN133 microRNA, human; D035683:MicroRNAs; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt
keywords: breast cancer; cell cycle; cell proliferation; epidermal growth factor receptor; microRNA