Abstract P4-11-28: Clinical significance of adiponectin receptor 1 (AdipoR1) expression in invasive breast cancer
Authors: Lee Younok , Lee Kang Yool , Lim Young Ah , Kim June Ho , Kim Lee Su 
Published: May 2015

Background: Recent studies have demonstrated that obesity is associated with an increased risk of breast cancer, but the mechanisms underlying this relationship remain to be fully elucidated. Adiponectin is one of major adipokines secreted from adipose tissue. Adiponectin serum levels have been shown to be inversely correlated with breast cancer risk. This protein is believed to act through AdipoR1 and has been suggested to play an important role in cancer development. The purpose of this study was to quantitatively evaluate the expression of AdipoR1 in invasive breast cancer tissue compared to normal breast tissue. And then, we analyzed clinical significance of AdipoR1 in invasive breast cancer.

Materials and Methods: Tissues were obtained from 269 patients who underwent curative surgery with no prior treatment for invasive ductal carcinoma from Jan. 2003 to Dec. 2008 in Hallym Sacred Heart Hospital. A tissue microarray (TMA) containing 269 invasive ductal carcinomas as well as 269 adjacent normal breast tissues was established from paraffin-embedded archived tissue for further analysis. AdipoR1 expression was investigated in epithelium and stroma by immunohistochemistry, using 1:1600 dilution of rabbit anti-adiponectin receptor antibody, and correlated with clinical and pathologic tumor parameters.

Results: In 269 patients, median follow-up period was 57 months. AdipoR1 was detected in epithelial and stromal component of both normal breast and invasive ductal carcinoma tissues. In epithelium, immunoreactivity for AdioR1 was much lower in cancer tissue than normal one (24.5% versus 72%). This trend was quite similar in stroma, although the gap between cancer and normal was a bit narrow (48.7% versus 77.6%). AdipoR1 was more expressed in stroma than in epithelium among invasive breast cancer (48.7% versus 24.5%). In clinicopathologic features, mean age at diagnosis of AdipoR1 expression group in both epithelium and stroma was older than negative group. Furthermore, in epithelial component, HER-2/neu overexpression rate was slightly higher in AdipoR1 negative group than in positive one (27.8% versus 15%, p=0.059). And, Ki67 was more expressed in AdipoR1 negative group than in positive one (49.5% versus 34.5%, p=0.051). However, in stroma component, there was no other difference between AdipoR1 expression and clinicopathologic parameters. In survival analysis, AdipoR1 expression group in stroma showed significantly better disease free survival (DFS) than negative group (p=0.02). DFS curve according to AdipoR1 expression in epithelium showed a quite similar trend with ones in stroma (p=0.06).

Conclusions: This study showed that AdipoR1 expression was suppressed in both epithelium and stroma of invasive breast cancer tissue compared to normal breast tissue, and AdipoR1 expression group in stroma showed significantly better DFS than negative group. Although it is earlist days yet to make conclusion, loss of AdipoR1 expression in stroma, possibly epithelium either, appears to play a role of independent risk factor to predict disease progression, somehow.

Citation Format: Younok Lee, Kang Yool Lee, Young Ah Lim, June Ho Kim, Lee Su Kim. Clinical significance of adiponectin receptor 1 (AdipoR1) expression in invasive breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-11-28.