title: Biased Expression of the FOXP3Δ3 Isoform in Aggressive Bladder Cancer Mediates Differentiation and Cisplatin Chemotherapy Resistance.
abstract: OBJECTIVE
  The transcriptional regulation mediating cancer cell differentiation into distinct molecular subtypes and modulating sensitivity to existing treatments is an enticing therapeutic target. Our objective was to characterize the ability of the forkhead/winged transcription factor FOXP3 to modulate the differentiation of bladder cancer.
  
  
  METHODS
  Expression of FOXP3 was analyzed by immunohistochemistry in a tumor microarray of 587 samples and overall survival in a subset of 187 patients following radical cystectomy. Functional assays were performed in SW780 and HT1376 cell lines in vitro and in vivo and gene expression profiling performed by RNA-Seq. Validation was undertaken using gene expression profiles of 131 patients from The Cancer Genome Atlas (TCGA) consortium in bladder cancer.
  
  
  RESULTS
  FOXP3 expression correlates with bladder cancer stage and inversely with overall survival, with biased expression of the FOXP3Δ3 isoform. Functional assays of FOXP3Δ3 demonstrated resistance to chemotherapy in vitro, whereas subcutaneous xenografts overexpressing FOXP3Δ3 developed larger and more poorly differentiated bladder cancers. RNA expression profiling revealed a unique FOXP3Δ3 gene signature supporting a role in chemotherapy resistance. Accordingly, knockdown of Foxp3 by siRNA in HT1376 cells conferred sensitivity to cisplatin- and gemcitabine-induced cytotoxicity. Validation in TCGA dataset demonstrated increased expression of FOXP3 in subtypes II to IV and skewing of molecular subtypes based on FOXP3Δ3-specific gene expression.
  
  
  CONCLUSIONS
  (i) Biased expression of the FOXP3Δ3 isoform in bladder cancer inversely correlates with overall survival, (ii) FOXP3Δ3 induces a unique gene program that mediates cancer differentiation, and (iii) FOXP3Δ3 may augment chemotherapy resistance. Clin Cancer Res; 22(21); 5349-61. ©2016 AACR.
authors.affiliation: Department of Urology, UCLA, Los Angeles, California.|Broad Stem Cell Research Center, UCLA, Los Angeles, California.
authors.forename: Hanwei
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Urology, UCLA, Los Angeles, California.
authors.forename: Kris
authors.initials: K
authors.lastname: Prado
authors.affiliation: Department of Biological Chemistry, UCLA, Los Angeles, California.
authors.forename: Kelvin X
authors.initials: KX
authors.lastname: Zhang
authors.affiliation: Molecular Biology Institute, UCLA, Los Angeles, California.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Peek
authors.affiliation: Department of Urology, UCLA, Los Angeles, California.
authors.forename: Jane
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Biostatistics, UCLA, Los Angeles, California.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Pathology, UCLA, Los Angeles, California.
authors.forename: Jiaoti
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Biostatistics, UCLA, Los Angeles, California.|Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Broad Stem Cell Research Center, UCLA, Los Angeles, California.|Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California.|Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, California.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pellegrini
authors.affiliation: Department of Urology, UCLA, Los Angeles, California. arnoldchin@mednet.ucla.edu.|Broad Stem Cell Research Center, UCLA, Los Angeles, California.|Molecular Biology Institute, UCLA, Los Angeles, California.|Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California.
authors.forename: Arnold I
authors.initials: AI
authors.lastname: Chin
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002460:Cell Line; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D015653:Cystectomy / Q000379:methods; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics*; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D020033:Protein Isoforms / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D001743:Urinary Bladder / Q000187:drug effects; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy / Q000235:genetics*; D000093542:Gemcitabine
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D003841:Deoxycytidine; D002945:Cisplatin; D000093542:Gemcitabine