Open Access Research

Overexpression of the secretory small GTPase Rab27B in human breast cancer correlates closely with lymph node metastasis and predicts poor prognosis

Jia-Xing Zhang1, Xiao-Xia Huang12, Man-Bo Cai3, Zhu-Ting Tong4, Jie-Wei Chen2, Dong Qian1, Yi-Ji Liao1, Hai-Xia Deng1, Ding-Zhun Liao2, Ma-Yan Huang2, Yi-Xin Zeng1, Dan Xie12* and Shi-Juan Mai1*

Author Affiliations

1 State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-Sen University, 651# Dongfeng Road East, Guangzhou, 510060, China

2 Department of Pathology, Cancer Center, Sun Yat-Sen University, 651# Dongfeng Road East, Guangzhou, 510060, China

3 Cancer Center, The First Affiliated Hospital, University of South China, Hengyang, China

4 Department of Radiotherapy, The First Affiliated Hospital, Anhui Medical University, Hefei, China

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Journal of Translational Medicine 2012, 10:242  doi:10.1186/1479-5876-10-242

Published: 5 December 2012

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.

Conclusion

Our findings suggest that overexpression of Rab27B in BC coincides with lymph node metastasis and acquisition of a poor prognostic phenotype.

Keywords:
Rab27B; Breast cancer; Prognosis; EMT; Metastasis