title: Restoring expression of miR-16: a novel approach to therapy for malignant pleural mesothelioma.
abstract: BACKGROUND
  Malignant pleural mesothelioma (MPM) is recalcitrant to treatment and new approaches to therapy are needed. Reduced expression of miR-15/16 in a range of cancer types has suggested a tumour suppressor function for these microRNAs, and re-expression has been shown to inhibit tumour cell proliferation. The miR-15/16 status in MPM is largely unknown.
  
  
  METHODS
  MicroRNA expression was analysed by TaqMan-based RT-qPCR in MPM tumour specimens and cell lines. MicroRNA expression was restored in vitro using microRNA mimics, and effects on proliferation, drug sensitivity and target gene expression were assessed. Xenograft-bearing mice were treated with miR-16 mimic packaged in minicells targeted with epidermal growth factor receptor (EGFR)-specific antibodies.
  
  
  RESULTS
  Expression of the miR-15 family was consistently downregulated in MPM tumour specimens and cell lines. A decrease of 4- to 22-fold was found when tumour specimens were compared with normal pleura. When MPM cell lines were compared with the normal mesothelial cell line MeT-5A, the downregulation of miR-15/16 was 2- to 10-fold. Using synthetic mimics to restore miR-15/16 expression led to growth inhibition in MPM cell lines but not in MeT-5A cells. Growth inhibition caused by miR-16 correlated with downregulation of target genes including Bcl-2 and CCND1, and miR-16 re-expression sensitised MPM cells to pemetrexed and gemcitabine. In xenograft-bearing nude mice, intravenous administration of miR-16 mimics packaged in minicells led to consistent and dose-dependent inhibition of MPM tumour growth.
  
  
  CONCLUSIONS
  The miR-15/16 family is downregulated and has tumour suppressor function in MPM. Restoring miR-16 expression represents a novel therapeutic approach for MPM.
authors.affiliation: Asbestos Diseases Research Institute, University of Sydney, Sydney, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Reid
authors.forename: M E
authors.initials: ME
authors.lastname: Pel
authors.forename: M B
authors.initials: MB
authors.lastname: Kirschner
authors.forename: Y Y
authors.initials: YY
authors.lastname: Cheng
authors.forename: N
authors.initials: N
authors.lastname: Mugridge
authors.forename: J
authors.initials: J
authors.lastname: Weiss
authors.forename: M
authors.initials: M
authors.lastname: Williams
authors.forename: C
authors.initials: C
authors.lastname: Wright
authors.forename: J J B
authors.initials: JJ
authors.lastname: Edelman
authors.forename: M P
authors.initials: MP
authors.lastname: Vallely
authors.forename: B C
authors.initials: BC
authors.lastname: McCaughan
authors.forename: S
authors.initials: S
authors.lastname: Klebe
authors.forename: H
authors.initials: H
authors.lastname: Brahmbhatt
authors.forename: J A
authors.initials: JA
authors.lastname: MacDiarmid
authors.forename: N
authors.initials: N
authors.lastname: van Zandwijk
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D015972:Gene Expression Regulation, Neoplastic; D005971:Glutamates / Q000494:pharmacology; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D008654:Mesothelioma / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D000086002:Mesothelioma, Malignant; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009368:Neoplasm Transplantation; D000068437:Pemetrexed; D010997:Pleural Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D034622:RNA Interference; D014162:Transfection; D047368:Tumor Burden; D000093542:Gemcitabine
chemical_list: D005971:Glutamates; C505361:MIRN15 microRNA, human; C505362:MIRN16 microRNA, human; D035683:MicroRNAs; D000068437:Pemetrexed; D003841:Deoxycytidine; D006147:Guanine; D000093542:Gemcitabine
keywords: mesothelioma; miR-16; microRNA; minicells