title: Overexpression of the secretory small GTPase Rab27B in human breast cancer correlates closely with lymph node metastasis and predicts poor prognosis.
abstract: BACKGROUND
  The secretory small GTPase Rab27b was recently identified as an oncogene in breast cancer (BC) in vivo and in vitro studies. This research was designed to further explore the clinical and prognostic significance of Rab27B in BC patients.
  
  
  METHODS
  The mRNA/protein expression level of Rab27B was examined by performing Real-time PCR, western blot, and immunohistochemistry (IHC) assays in 12 paired BC tissues and matched adjacent noncancerous tissues (NAT). Then we carried out IHC assay in a large cohort of 221 invasive BC tissues, 22 normal breast tissues, 40 fibroadenoma (FA), 30 ductual carcinoma in situ (DCIS) and 40 metastatic lymph nodes (LNs). The receiver operating characteristic curve method was applied to obtain the optimal cutoff value for high Rab27B expression. Epithelial-mesenchymal transition (EMT) marker expression levels were detected in relation to Rab27B expression.
  
  
  RESULTS
  We observed that the increased expression of Rab27B was dependent upon the magnitude of cancer progression (P < 0.001). The elevated expression of Rab27B was closely correlated with lymph node metastasis, advanced clinical stage, ascending pathology classification, and positive ER status. Furthermore, patients with high expression of Rab27B had inferior survival outcomes. Multivariate Cox regression analysis proved that Rab27B was a significantly independent risk factor for patients' survival (P < 0.001). Furthermore, a significant positive relationship was observed between Rab27B expression and elevated mesenchymal EMT markers.
  
  
  CONCLUSIONS
  Our findings suggest that overexpression of Rab27B in BC coincides with lymph node metastasis and acquisition of a poor prognostic phenotype.
authors.affiliation: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, 651# Dongfeng Road East, Guangzhou 510060, China.
authors.forename: Jia-Xing
authors.initials: JX
authors.lastname: Zhang
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Huang
authors.forename: Man-Bo
authors.initials: MB
authors.lastname: Cai
authors.forename: Zhu-Ting
authors.initials: ZT
authors.lastname: Tong
authors.forename: Jie-Wei
authors.initials: JW
authors.lastname: Chen
authors.forename: Dong
authors.initials: D
authors.lastname: Qian
authors.forename: Yi-Ji
authors.initials: YJ
authors.lastname: Liao
authors.forename: Hai-Xia
authors.initials: HX
authors.lastname: Deng
authors.forename: Ding-Zhun
authors.initials: DZ
authors.lastname: Liao
authors.forename: Ma-Yan
authors.initials: MY
authors.lastname: Huang
authors.forename: Yi-Xin
authors.initials: YX
authors.lastname: Zeng
authors.forename: Dan
authors.initials: D
authors.lastname: Xie
authors.forename: Shi-Juan
authors.initials: SJ
authors.lastname: Mai
mesh_terms: D001483:Base Sequence; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D015331:Cohort Studies; D017931:DNA Primers; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D011379:Prognosis; D060888:Real-Time Polymerase Chain Reaction; D015996:Survival Rate; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; C512960:Rab27B protein, human; D020691:rab GTP-Binding Proteins