title: PIK3CA dependence and sensitivity to therapeutic targeting in urothelial carcinoma.
abstract: Many urothelial carcinomas (UC) contain activating PIK3CA mutations. In telomerase-immortalized normal urothelial cells (TERT-NHUC), ectopic expression of mutant PIK3CA induces PI3K pathway activation, cell proliferation and cell migration. However, it is not clear whether advanced UC tumors are PIK3CA-dependent and whether PI3K pathway inhibition is a good therapeutic option in such cases.
  
  
  
  We used retrovirus-mediated delivery of shRNA to knock down mutant PIK3CA in UC cell lines and assessed effects on pathway activation, cell proliferation, migration and tumorigenicity. The effect of the class I PI3K inhibitor GDC-0941 was assessed in a panel of UC cell lines with a range of known molecular alterations in the PI3K pathway.
  
  
  
  Specific knockdown of PIK3CA inhibited proliferation, migration, anchorage-independent growth and in vivo tumor growth of cells with PIK3CA mutations. Sensitivity to GDC-0941 was dependent on hotspot PIK3CA mutation status. Cells with rare PIK3CA mutations and co-occurring TSC1 or PTEN mutations were less sensitive. Furthermore, downstream PI3K pathway alterations in TSC1 or PTEN or co-occurring AKT1 and RAS gene mutations were associated with GDC-0941 resistance.
  
  
  
  Mutant PIK3CA is a potent oncogenic driver in many UC cell lines and may represent a valuable therapeutic target in advanced bladder cancer.
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK.
authors.forename: R L
authors.initials: RL
authors.lastname: Ross
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK.
authors.forename: H R
authors.initials: HR
authors.lastname: McPherson
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK.
authors.forename: L
authors.initials: L
authors.lastname: Kettlewell
authors.affiliation: Institute of Cancer Therapeutics, University of Bradford, Richmond Road, Bradford, BD7 1DP, UK.
authors.forename: S D
authors.initials: SD
authors.lastname: Shnyder
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK.
authors.forename: C D
authors.initials: CD
authors.lastname: Hurst
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK.
authors.forename: O
authors.initials: O
authors.lastname: Alder
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Beckett Street, Leeds, LS9 7TF, UK. m.a.knowles@leeds.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: Knowles
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002295:Carcinoma, Transitional Cell / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D058534:Class I Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D064593:Heterografts; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism*
chemical_list: D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human
keywords: Bladder cancer; PI3K signaling; PIK3CA; Urothelium