title: microRNA-145 modulates epithelial-mesenchymal transition and suppresses proliferation, migration and invasion by targeting SIP1 in human cervical cancer cells.
abstract: OBJECTIVE
  Previously, it has been reported that microRNA-145 (miR-145) is lowly expressed in human cervical cancers and that its putative tumour suppressive role may be attributed to epithelial-mesenchymal transition (EMT) regulation. Here, we aimed to assess whether miR-145 may affect EMT-associated markers/genes and suppress cervical cancer growth and motility, and to provide a mechanistic basis for these phenomena.
  
  
  METHODS
  The identification of the SMAD-interacting protein 1 (SIP1) mRNA as putative miR-145 target was investigated using a 3' untranslated region (3'UTR) luciferase assay and Western blotting, respectively. The functional effects of exogenous miR-145 expression, miR-145 suppression or siRNA-mediated SIP1 expression down-regulation in cervical cancer-derived C33A and SiHa cells were analysed using Western blotting, BrdU incorporation (proliferation), transwell migration and invasion assays. In addition, the expression levels of miR-145 and SIP1 were determined in primary human cervical cancer and non-cancer tissue samples using qRT-PCR.
  
  
  RESULTS
  We found that miR-145 binds to the wild-type 3'UTR of SIP1, but not to its mutant counterpart, and that, through this binding, miR-145 can effectively down-regulate SIP1 expression. In addition, we found that exogenous miR-145 expression or siRNA-mediated down-regulation of SIP1 expression attenuates the proliferation, migration and invasion of C33A and SiHa cells and alters the expression of the EMT-associated markers CDH1, VIM and SNAI1, whereas inhibition of endogenous miR-145 expression elicited the opposite effects. The expression of miR-145 in cervical cancer tissue samples was found to be low, while that of SIP1 was found to be high compared to non-cancerous cervical tissues. An inverse expression correlation between the two was substantiated through the anlaysis of data deposited in the TCGA database.
  
  
  CONCLUSIONS
  Our data indicate that low miR-145 expression levels in conjunction with elevated SIP1 expression levels may contribute to cervical cancer development. MiR-145-mediated regulation of SIP1 provides a novel mechanistic basis for its tumour suppressive mode of action in human cervical cancer cells.
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India.
authors.forename: Anusha
authors.initials: A
authors.lastname: Sathyanarayanan
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India.
authors.forename: Karthik Subramanian
authors.initials: KS
authors.lastname: Chandrasekaran
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India. karuna@iitm.ac.in.
authors.forename: Devarajan
authors.identifier: http://orcid.org/0000-0001-9331-8947
authors.initials: D
authors.lastname: Karunagaran
mesh_terms: D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000235:genetics* / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; C108381:GEMIN2 protein, human; C541010:MIRN145 microRNA, human; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins
keywords: Epithelial-mesenchymal transition; Human cervical cancer; Invasion; Migration; Proliferation; SIP1; microRNA-145