title: YAP expression in normal and neoplastic breast tissue: an immunohistochemical study.
abstract: OBJECTIVE
  Yes-associated protein (YAP) is a transcriptional factor involved in normal cell proliferation, apoptosis and carcinogenesis; however, its contribution to breast cancer (BC) is still controversial. We undertook this study to compare the expression of YAP by immunohistochemistry (IHC) in normal breast tissue of women without breast cancer (BC) (controls), non-neoplastic breast tissue in women with cancer (internal controls) and in four different subtypes of invasive ductal carcinoma.
  
  
  METHODS
  There were 17 controls and 105 tumor cases (53 luminal A, 15 luminal B, 20 overexpression of HER2 and 17 triple negative cases) studied by IHC. Statistical analysis included χ(2) for linear trend (Extended Mantel-Haenszel).
  
  
  RESULTS
  There were 40% of internal controls that showed expression of YAP in myoepithelial cells, whereas in controls expression was 100%. In controls, 3/17 (17.6%) showed cytoplasmic staining in luminal cells. There was a significant difference in nuclear expression between the ductal BC subtypes. Luminal A had 4% of positive cases with <10% of cells affected in each case; in contrast, there were 17-20% of positive cases in the other groups with 50% or more of stained cells. YAP expression in stromal cells was not observed in controls or in triple-negative cases, and luminal B pattern had the highest YAP nuclear expression (20%).
  
  
  CONCLUSIONS
  YAP showed decreased expression in tumor cells compared with normal breast tissue. These findings are consistent with a role of YAP as a suppressor gene in BC and show differences in YAP expression in different patterns of ductal BC.
authors.affiliation: Instituto de Medicina Forense, Juan Pablo II, Esq, Reyes Heroles Fracc. Costa Verde, Boca del Río, Veracruz, Mexico.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Jaramillo-Rodríguez
authors.affiliation: Facultad de Enfermería, Universidad Autónoma de Nuevo León, Monterrey, NL, Mexico.
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Cerda-Flores
authors.affiliation: Instituto de Medicina Forense, Universidad Veracruzana, Boca del Río, Veracruz, Mexico.
authors.forename: Ruben
authors.initials: R
authors.lastname: Ruiz-Ramos
authors.affiliation: Centro de Investigación Biomédica de la Facultad de Medicina, Universidad Autónoma de Coahuila, Torréon, Coahuila, Mexico.
authors.forename: Francisco C
authors.initials: FC
authors.lastname: López-Márquez
authors.affiliation: Instituto de Medicina Forense, Universidad Veracruzana, Boca del Río, Veracruz, Mexico. Electronic address: acald911@hotmail.com.
authors.forename: Ana Laura
authors.initials: AL
authors.lastname: Calderón-Garcidueñas
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000328:Adult; D000368:Aged; D001940:Breast / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010750:Phosphoproteins / Q000378:metabolism*; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D010750:Phosphoproteins; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human
keywords: Breast cancer; Immunohistochemistry; Yes-associated protein