title: Mutational analysis of hedgehog signaling pathway genes in human malignant mesothelioma.
abstract: BACKGROUND
  The Hedgehog (HH) signaling pathway is critical for embryonic development and adult homeostasis. Recent studies have identified regulatory roles for this pathway in certain cancers with mutations in the HH pathway genes. The extent to which mutations of the HH pathway genes are involved in the pathogenesis of malignant mesothelioma (MMe) is unknown.
  
  
  RESULTS
  Real-time PCR analysis of HH pathway genes PTCH1, GLI1 and GLI2 were performed on 7 human MMe cell lines. Exon sequencing of 13 HH pathway genes was also performed in cell lines and human MMe tumors. In silico programs were used to predict the likelihood that an amino-acid substitution would have a functional effect. GLI1, GLI2 and PTCH1 were highly expressed in MMe cells, indicative of active HH signaling. PTCH1, SMO and SUFU mutations were found in 2 of 11 MMe cell lines examined. A non-synonymous missense SUFU mutation (p.T411M) was identified in LO68 cells. In silico characterization of the SUFU mutant suggested that the p.T411M mutation might alter protein function. However, we were unable to demonstrate any functional effect of this mutation on Gli activity. Deletion of exons of the PTCH1 gene was found in JU77 cells, resulting in loss of one of two extracellular loops implicated in HH ligand binding and the intracellular C-terminal domain. A 3-bp insertion (69_70insCTG) in SMO, predicting an additional leucine residue in the signal peptide segment of SMO protein was also identified in LO68 cells and a MMe tumour.
  
  
  CONCLUSIONS
  We identified the first novel mutations in PTCH1, SUFU and SMO associated with MMe. Although HH pathway mutations are relatively rare in MMe, these data suggest a possible role for dysfunctional HH pathway in the pathogenesis of a subgroup of MMe and help rationalize the exploration of HH pathway inhibitors for MMe therapy.
authors.affiliation: Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia.
authors.forename: Chuan Bian
authors.initials: CB
authors.lastname: Lim
authors.forename: Cecilia M
authors.initials: CM
authors.lastname: Prêle
authors.forename: Hui Min
authors.initials: HM
authors.lastname: Cheah
authors.forename: Yuen Yee
authors.initials: YY
authors.lastname: Cheng
authors.forename: Sonja
authors.initials: S
authors.lastname: Klebe
authors.forename: Glen
authors.initials: G
authors.lastname: Reid
authors.forename: D Neil
authors.initials: DN
authors.lastname: Watkins
authors.forename: Svetlana
authors.initials: S
authors.lastname: Baltic
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Thompson
authors.forename: Steven E
authors.initials: SE
authors.lastname: Mutsaers
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D053823:Hedgehog Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008654:Mesothelioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D053823:Hedgehog Proteins