title: Expression of estrogen receptors-alpha and -beta in bladder cancer cell lines and human bladder tumor tissue.
abstract: BACKGROUND
  Estrogen receptors (ERs) are known to mediate important physiologic responses as well as the growth of some tumors in response to estradiol stimulation. In a previous study the selective ER modulator raloxifene was shown to induce apoptosis in an ERbeta-positive bladder cancer cell line. However, the expression of ERbeta in human bladder cancer has not been thoroughly investigated.
  
  
  METHODS
  ERalpha and ERbeta expression in 224 bladder tumor samples was evaluated using tissue microarray and immunohistochemistry. Levels of ERalpha and ERbeta protein and mRNA expression were determined in several bladder cancer cell lines using quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis. The effect of estradiol and antiestrogen treatments on RT4 bladder cancer cell growth was determined by cell proliferation assays.
  
  
  RESULTS
  Analyses revealed that only 2 human bladder cancers weakly expressed ERalpha. In contrast, the expression of ERbeta was detected in 141 tumors (63%). ERbeta was expressed in 58% of WHO Grade 1 and 2 tumors, whereas 70% of Grade 3 tumors demonstrated expression (P = .085). Importantly, although only 53% and 55% of Ta and T1 tumors demonstrated ERbeta expression, 80% of T2, 81% of T3, and 75% of T4 tumors showed ERbeta expression. The differences in ERbeta expression between Ta/T1 and T2/T3/T4 tumors were found to be highly significant (P < .001). Metastatic transitional cell carcinomas had ERbeta expression (80%) comparable to that of muscle invasive bladder cancers. Western blot analysis detected ERbeta protein expression in each of the 5 bladder cancer cell lines tested, whereas no or very low levels of ERalpha were found. Quantitative RT-PCR revealed that higher levels of ERbeta than ERalpha mRNA were present in 5637, T-24, TSU-Pr1, and TCC-Sup bladder cancer cells, whereas ER-alpha mRNA levels were greater than ERbeta in RT4 cells. Treatment with 17beta-estradiol modestly increased RT4 cell growth, whereas the antiestrogens, 4-hydroxtamoxifen, raloxifene, or ICI 182,780 inhibited the growth of RT4 cells.
  
  
  CONCLUSIONS
  ERbeta is the dominant receptor expressed in bladder cancer cell lines and in the majority of human bladder tumors. Moreover, the degree of ERbeta expression increases with increasing stage and grade of differentiation. Antiestrogens have an inhibitory effect on the growth of bladder cancer cells in vitro.
authors.affiliation: Department of Pathology, The Methodist Hospital and Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Steven S
authors.initials: SS
authors.lastname: Shen
authors.forename: Carolyn L
authors.initials: CL
authors.lastname: Smith
authors.forename: Jer-Tsong
authors.initials: JT
authors.lastname: Hsieh
authors.forename: Jiang
authors.initials: J
authors.lastname: Yu
authors.forename: Isaac Y
authors.initials: IY
authors.lastname: Kim
authors.forename: Weiguo
authors.initials: W
authors.lastname: Jian
authors.forename: Guru
authors.initials: G
authors.lastname: Sonpavde
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Ayala
authors.forename: Mamoun
authors.initials: M
authors.lastname: Younes
authors.forename: Seth P
authors.initials: SP
authors.lastname: Lerner
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002295:Carcinoma, Transitional Cell / Q000737:chemistry* / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D047629:Estrogen Receptor beta / Q000032:analysis / Q000235:genetics / Q000502:physiology; D000077267:Fulvestrant; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D046228:Microarray Analysis; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020849:Raloxifene Hydrochloride / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology; D001749:Urinary Bladder Neoplasms / Q000737:chemistry* / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology
chemical_list: D000970:Antineoplastic Agents; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D013629:Tamoxifen; D000077267:Fulvestrant; D020849:Raloxifene Hydrochloride; D004958:Estradiol