title: The MyD88+ phenotype is an adverse prognostic factor in epithelial ovarian cancer.
abstract: The prognosis of epithelial ovarian cancer is poor in part due to the high frequency of chemoresistance. Recent evidence points to the Toll-like receptor-4 (TLR4), and particularly its adaptor protein MyD88, as one potential mediator of this resistance. This study aims to provide further evidence that MyD88 positive cancer cells are clinically significant, stem-like and reproducibly detectable for the purposes of prognostic stratification. Expression of TLR4 and MyD88 was assessed immunohistochemically in 198 paraffin-embedded ovarian tissues and in an embryonal carcinoma model of cancer stemness. In parallel, expression of TLR4 and MyD88 mRNA and regulatory microRNAs (miR-21 and miR-146a) was assessed, as well as in a series of chemosensitive and resistant cancer cells lines. Functional analysis of the pathway was assessed in chemoresistant SKOV-3 ovarian cancer cells. TLR4 and MyD88 expression can be reproducibly assessed via immunohistochemistry using a semi-quantitative scoring system. TLR4 expression was present in all ovarian epithelium (normal and neoplastic), whereas MyD88 was restricted to neoplastic cells, independent of tumour grade and associated with reduced progression-free and overall survival, in an immunohistological specific subset of serous carcinomas, p<0.05. MiR-21 and miR-146a expression was significantly increased in MyD88 negative cancers (p<0.05), indicating their participation in regulation. Significant alterations in MyD88 mRNA expression were observed between chemosensitive and chemoresistant cells and tissue. Knockdown of TLR4 in SKOV-3 ovarian cells recovered chemosensitivity. Knockdown of MyD88 alone did not. MyD88 expression was down-regulated in differentiated embryonal carcinoma (NTera2) cells, supporting the MyD88+ cancer stem cell hypothesis. Our findings demonstrate that expression of MyD88 is associated with significantly reduced patient survival and altered microRNA levels and suggest an intact/functioning TLR4/MyD88 pathway is required for acquisition of the chemoresistant phenotype. Ex vivo manipulation of ovarian cancer stem cell (CSC) differentiation can decrease MyD88 expression, providing a potentially valuable CSC model for ovarian cancer.
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Charles J
authors: CJ
authors: d'Adhemar
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Cathy D
authors: CD
authors: Spillane
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Michael F
authors: MF
authors: Gallagher
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Mark
authors: M
authors: Bates
authors: Department of Pathology, Coombe Women's & Infants University Hospital, Dublin, Ireland.
authors: Katie M
authors: KM
authors: Costello
authors: Department of Pathology, Coombe Women's & Infants University Hospital, Dublin, Ireland.
authors: Jacqui
authors: J
authors: Barry-O'Crowley
authors: Department of Obstetrics and Gynaecology, Trinity College Dublin, Dublin, Ireland.
authors: Kathryn
authors: K
authors: Haley
authors: Department of Pathology, Coombe Women's & Infants University Hospital, Dublin, Ireland.
authors: Niamh
authors: N
authors: Kernan
authors: Department of Pathology, Coombe Women's & Infants University Hospital, Dublin, Ireland.
authors: Ciara
authors: C
authors: Murphy
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Paul C
authors: PC
authors: Smyth
authors: Translational Research Institute, Princess Alexandra Hospital, Brisbane, Australia.
authors: Ken
authors: K
authors: O'Byrne
authors: College of Health Sciences, University College Dublin, Belfield, Dublin, Ireland.
authors: Stephen
authors: S
authors: Pennington
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Aoife A
authors: AA
authors: Cooke
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Brendan
authors: B
authors: Ffrench
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Cara M
authors: CM
authors: Martin
authors: Department of Medical Oncology, St. James's Hospital, Dublin, Ireland.
authors: Dearbhaile
authors: D
authors: O'Donnell
authors: Department of Medical Oncology, Royal College of Surgeons, Dublin, Ireland.
authors: Bryan
authors: B
authors: Hennessy
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Britta
authors: B
authors: Stordal
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Stephen
authors: S
authors: Finn
authors: College of Health Sciences, University College Dublin, Belfield, Dublin, Ireland.
authors: Amanda
authors: A
authors: McCann
authors: Department of Obstetrics and Gynaecology, Trinity College Dublin, Dublin, Ireland.
authors: Noreen
authors: N
authors: Gleeson
authors: Department of Obstetrics and Gynaecology, Trinity College Dublin, Dublin, Ireland.
authors: Tom
authors: T
authors: D'Arcy
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Brian
authors: B
authors: Flood
authors: Department of Biochemistry, Trinity College Dublin, Ireland.
authors: Luke A J
authors: LA
authors: O'Neill
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland.
authors: Orla
authors: O
authors: Sheils
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland; Department of Obstetrics and Gynaecology, Trinity College Dublin, Dublin, Ireland.
authors: Sharon
authors: S
authors: O'Toole
authors: Department of Histopathology, Trinity College Dublin, Dublin, Ireland; Department of Pathology, Coombe Women's & Infants University Hospital, Dublin, Ireland.
authors: John J
authors: JJ
authors: O'Leary
mesh_terms: D000368:Aged; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D000077216:Carcinoma, Ovarian Epithelial; D045744:Cell Line, Tumor; D018284:Cystadenocarcinoma, Serous / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics* / Q000378:metabolism; D009375:Neoplasms, Glandular and Epithelial / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D010051:Ovarian Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality; D017239:Paclitaxel / Q000494:pharmacology; D010641:Phenotype; D011379:Prognosis; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016019:Survival Analysis; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C542542:MIRN146 microRNA, human; C524940:MIRN21 microRNA, human; C507779:MYD88 protein, human; D035683:MicroRNAs; D053594:Myeloid Differentiation Factor 88; D034741:RNA, Small Interfering; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D017239:Paclitaxel