title: miRNA-135a promotes breast cancer cell migration and invasion by targeting HOXA10.
abstract: BACKGROUND
  miRNAs are a group of small RNA molecules regulating target genes by inducing mRNA degradation or translational repression. Aberrant expression of miRNAs correlates with various cancers. Although miR-135a has been implicated in several other cancers, its role in breast cancer is unknown. HOXA10 however, is associated with multiple cancer types and was recently shown to induce p53 expression in breast cancer cells and reduce their invasive ability. Because HOXA10 is a confirmed miR-135a target in more than one tissue, we examined miR-135a levels in relation to breast cancer phenotypes to determine if miR-135a plays role in this cancer type.
  
  
  METHODS
  Expression levels of miR-135a in tissues and cells were determined by poly (A)-RT PCR. The effect of miR-135a on proliferation was evaluated by CCK8 assay, cell migration and invasion were evaluated by transwell migration and invasion assays, and target protein expression was determined by western blotting. GFP and luciferase reporter plasmids were constructed to confirm the action of miR-135a on downstream target genes including HOXA10. Results are reported as means ± S.D. and differences were tested for significance using 2-sided Student"s t-test.
  
  
  RESULTS
  Here we report that miR-135a was highly expressed in metastatic breast tumors. We found that the expression of miR-135a was required for the migration and invasion of breast cancer cells, but not their proliferation. HOXA10, which encodes a transcription factor required for embryonic development and is a metastasis suppressor in breast cancer, was shown to be a direct target of miR-135a in breast cancer cells. Our analysis showed that miR-135a suppressed the expression of HOXA10 both at the mRNA and protein level, and its ability to promote cellular migration and invasion was partially reversed by overexpression of HOXA10.
  
  
  CONCLUSIONS
  In summary, our results indicate that miR-135a is an onco-miRNA that can promote breast cancer cell migration and invasion. HOXA10 is a target gene for miR-135a in breast cancer cells and overexpression of HOXA10 can partially reverse the miR-135a invasive phenotype.
authors.affiliation: Key Laboratory of Molecular Medicine, Ministry of Education, Shanghai Medical College, Fudan University, China.
authors.forename: Yating
authors.initials: Y
authors.lastname: Chen
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Huijun
authors.initials: H
authors.lastname: Wang
authors.forename: Jiayi
authors.initials: J
authors.lastname: Zhao
authors.forename: Cheng
authors.initials: C
authors.lastname: Xu
authors.forename: Yingying
authors.initials: Y
authors.lastname: Du
authors.forename: Xin
authors.initials: X
authors.lastname: Luo
authors.forename: Fengyun
authors.initials: F
authors.lastname: Zheng
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhang
authors.forename: Duan
authors.initials: D
authors.lastname: Ma
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D005260:Female; D005786:Gene Expression Regulation; D000080905:Homeobox A10 Proteins; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000502:physiology*; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000080905:Homeobox A10 Proteins; D018398:Homeodomain Proteins; C544965:MIRN135 microRNA, human; D035683:MicroRNAs; D009363:Neoplasm Proteins; C069634:HOXA10 protein, human