Abstract P2-07-06: Periostin is associated with breast tumor progression and epithelial periostin expression is correlated with poor survival in patients with invasive breast carcinoma

Background: Invasion and metastasis are the direct causes of mortality in patients with breast cancer and require reciprocal interactions between cancer cells and the extracellular matrix (ECM). Periostin, a fasciclin-containing adhesive ECM glycoprotein, is frequently overexpressed in various types of human cancer, and its overexpression in cancer-associated stroma and/or cancer cells is usually associated with poor clinical outcomes. However, the expression of periostin in the successive steps of breast tumorigenesis and its association with outcome variables have not been well established in breast carcinoma. The purposes of the present study were to assess the role of periostin alteration in breast tumorigenesis and evaluate the putative prognostic value of periostin as a function of its compartmentalization. Materials and Methods: Immunohistochemical staining with anti-periostin antibody was performed in a total of 300 patients (26 patients with normal breasts, 76 patients with ductal carcinoma in situ [DCIS], and 198 patients with invasive breast carcinoma [IBC]) using tissue microarray. Periostin immunoreactivity was assessed in both epithelial tissue and the surrounding stromal compartment. In addition, the mRNA and protein expression of periostin was analyzed in 10 paired normal/invasive cancer frozen specimens by quantitative real time-polymerase chain reaction and western blot analysis, respectively. Results: Periostin mRNA and protein expression in cancer tissues was increased compared with that in adjacent normal tissues. Both epithelial and stromal periostin staining scores were significantly increased with disease progression in a stepwise manner to DCIS and IBC compared with those in normal breast tissues (P = 0.000 and 0.000, respectively). High epithelial and stromal periostin expression was observed in 109 of 189 (57.7%) and 158 of 189 (83.6%) cases of IBC, respectively. High epithelial periostin expression was more frequently observed in the distant metastatic relapse-positive group than in the distant metastatic relapse-negative group (41 [80.4%] of 51 cases versus 68 [49.3%] of 138 cases [P = 0.000]). Furthermore, high epithelial periostin expression was associated with reduced disease-free and overall survival on univariate and multivariate analyses. Conclusion: Periostin might play an important role in the progression of breast tumor, and epithelial periostin expression may serve as a new parameter for prognostic prediction in patients with IBC. Further study of periostin expression and its potential as a target of therapy for IBC appears warranted. Citation Format: Lee JS, Kim G-E, Park MH, Yoon JH. Periostin is associated with breast tumor progression and epithelial periostin expression is correlated with poor survival in patients with invasive breast carcinoma. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-07-06.