title: Microcell-mediated chromosome transfer identifies EPB41L3 as a functional suppressor of epithelial ovarian cancers.
abstract: We used a functional complementation approach to identify tumor-suppressor genes and putative therapeutic targets for ovarian cancer. Microcell-mediated transfer of chromosome 18 in the ovarian cancer cell line TOV21G induced in vitro and in vivo neoplastic suppression. Gene expression microarray profiling in TOV21G(+18) hybrids identified 14 candidate genes on chromosome 18 that were significantly overexpressed and therefore associated with neoplastic suppression. Further analysis of messenger RNA and protein expression for these genes in additional ovarian cancer cell lines indicated that EPB41L3 (erythrocyte membrane protein band 4.1-like 3, alternative names DAL-1 and 4.1B) was a candidate ovarian cancer-suppressor gene. Immunoblot analysis showed that EPB41L3 was activated in TOV21G(+18) hybrids, expressed in normal ovarian epithelial cell lines, but was absent in 15 (78%) of 19 ovarian cancer cell lines. Using immunohistochemistry, 66% of 794 invasive ovarian tumors showed no EPB41L3 expression compared with only 24% of benign ovarian tumors and 0% of normal ovarian epithelial tissues. EPB41L3 was extensively methylated in ovarian cancer cell lines and primary ovarian tumors compared with normal tissues (P = .00004), suggesting this may be the mechanism of gene inactivation in ovarian cancers. Constitutive reexpression of EPB41L3 in a three-dimensional multicellular spheroid model of ovarian cancer caused significant growth suppression and induced apoptosis. Transmission and scanning electron microscopy demonstrated many similarities between EPB41L3-expressing cells and chromosome 18 donor-recipient hybrids, suggesting that EPB41L3 is the gene responsible for neoplastic suppression after chromosome 18 transfer. Finally, an inducible model of EPB41L3 expression in three-dimensional spheroids confirmed that reexpression of EPB41L3 induces extensive apoptotic cell death in ovarian cancers.
authors.affiliation: EGA Institute for Women's Health, Gynaecological Cancer Research Laboratories, University College London, London, UK.
authors.forename: Dimitra
authors.initials: D
authors.lastname: Dafou
authors.forename: Barbara
authors.initials: B
authors.lastname: Grun
authors.forename: John
authors.initials: J
authors.lastname: Sinclair
authors.forename: Kate
authors.initials: K
authors.lastname: Lawrenson
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Benjamin
authors.forename: Estrid
authors.initials: E
authors.lastname: Hogdall
authors.forename: Susanne
authors.initials: S
authors.lastname: Kruger-Kjaer
authors.forename: Lise
authors.initials: L
authors.lastname: Christensen
authors.forename: Heidi M
authors.initials: HM
authors.lastname: Sowter
authors.forename: Ahmed
authors.initials: A
authors.lastname: Al-Attar
authors.forename: Richard
authors.initials: R
authors.lastname: Edmondson
authors.forename: Stephen
authors.initials: S
authors.lastname: Darby
authors.forename: Andrew
authors.initials: A
authors.lastname: Berchuck
authors.forename: Peter W
authors.initials: PW
authors.lastname: Laird
authors.forename: C Leigh
authors.initials: CL
authors.lastname: Pearce
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Ramus
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Jacobs
authors.forename: Simon A
authors.initials: SA
authors.lastname: Gayther
mesh_terms: D017209:Apoptosis / Q000235:genetics; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D018014:Gene Transfer Techniques; D016147:Genes, Tumor Suppressor / Q000502:physiology; D056726:Genetic Association Studies; D006801:Humans; D006822:Hybrid Cells / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D046228:Microarray Analysis; D008840:Microfilament Proteins; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics*; D018874:Spheroids, Cellular / Q000378:metabolism / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: C116887:EPB41L3 protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D025521:Tumor Suppressor Proteins