Expression of NgBR Is Highly Associated with Estrogen Receptor Alpha and Survivin in Breast Cancer

Bei Wang,Baofeng Zhao,Amanda Kong,Qing Robert Miao,Paula North,Jian Huang,Adriano Angelucci

doi:10.1371/journal.pone.0078083

Abstract

NgBR is a type I receptor with a single transmembrane domain and was identified as a specific receptor for Nogo-B. Our recent findings demonstrated that NgBR binds farnesylated Ras and recruits Ras to the plasma membrane, which is a critical step required for the activation of Ras signaling in human breast cancer cells and tumorigenesis. Here, we first use immunohistochemistry and real-time PCR approaches to examine the expression patterns of Nogo-B and NgBR in both normal and breast tumor tissues. Then, we examine the relationship between NgBR expression and molecular subtypes of breast cancer, and the roles of NgBR in estrogen-dependent survivin signaling pathway. Results showed that NgBR and Nogo-B protein were detected in both normal and breast tumor tissues. However, the expression of Nogo-B and NgBR in breast tumor tissue was much stronger than in normal breast tissue. The statistical analysis demonstrated that NgBR is highly associated with ER-positive/HER2-negative breast cancer. We also found that the expression of NgBR has a strong correlation with the expression of survivin, which is a well-known apoptosis inhibitor. The correlation between NgBR and survivin gene expression was further confirmed by real-time PCR. In vitro results also demonstrated that estradiol induces the expression of survivin in ER-positive T47D breast tumor cells but not in ER-negative MDA-MB-468 breast tumor cells. NgBR knockdown with siRNA abolishes estradiol-induced survivin expression in ER-positive T47D cells but not in ER-negative MDA-MB-468 cells. In addition, estradiol increases the expression of survivin and cell growth in ER-positive MCF-7 and T47D cells whereas knockdown of NgBR with siRNA reduces estradiol-induced survivin expression and cell growth. In summary, these results indicate that NgBR is a new molecular marker for breast cancer. The data suggest that the expression of NgBR may be essential in promoting ER-positive tumor cell proliferation via survivin induction in breast cancer.

Highlights

Breast cancer is the most common carcinoma in women and the second most common cause of cancer death in females [1]
Specificity of Nogo-B and NgBR IHC Staining To confirm the specificity of NgBR and Nogo-B IHC, we performed IHC staining in human invasive ductal carcinoma (IDC) tissue sections and used primary antibodies preabsorbed with their corresponding epitope peptide-conjugated beads as negative controls
Ectopic expression of the Nogo-B/ASY gene led to extensive apoptosis, in cancer cells [22]

Summary

Introduction

Breast cancer is the most common carcinoma in women and the second most common cause of cancer death in females [1]. 80% of all diagnosed in situ and invasive breast cancers are of ductal origin [1,6]. In 2012, an estimated 229,060 new cases of breast cancer were expected to be diagnosed and approximately 39,920 deaths were expected to occur in the United States alone [7]. Breast cancer is the most common malignant disease in Western women, and distant metastasis are the main cause of death [6]. We reveal a new potential diagnosis marker for breast invasive ductal carcinoma (IDC)

Methods

Results

Conclusion