Differential expression of the 150-kd oxygen-regulated protein (ORP150) in benign, pre-malignant and malignant breast tissue

Abstract

10770 Background: Heat shock protein, ORP150, plays a role in hypoxia/ischemia and angiogenesis. Preliminary studies demonstrate increased ORP 150 expression in human cancer, and associate its over expression with aggressive tumor biology. This study further evaluates ORP150 expression in different stages of breast cancer, such as benign, pre-malignant and malignant breast lesions and correlates it with clinical-pathological data. Methods: Sixty-six prospectively collected paraffin-embedded breast tissue sections were reviewed for diagnostic confirmation (normal, n=25; DCIS, n=20; invasive breast cancer (Ca), n=21) and stained using ORP150 antibody immunohistochemistry (IHC). Antibody-staining levels in the benign, DCIS and invasive component of each lesion were reviewed independently by two pathologists and scored: 0 (lowest) to 3+ (highest). Clinical-pathological data was compared with ORP150 staining using ANOVA or T-Test as appropriate with significance determined by p<0.05. Results: Significant differential ORP150 staining was detected in benign-normal versus benign adjacent to invasive cancer, as well as in benign adjacent to DCIS versus benign adjacent to invasive cancer. ORP150 expression in the invasive portion of the breast cancer correlated significantly with tumor grade and absence of hormone receptor expression, presence of lymphovascular invasion and lymph node metastasis. Conclusions: ORP150 expression in breast cancer is associated with poor prognostic histological factors. As ORP150 is differentially expressed in benign tissue adjacent to invasive cancer, further study is warranted to determine its utility in detecting occult invasive cancer within benign biopsy specimens, as well as its putative role in tumor-stromal cell interactions. [Table: see text] No significant financial relationships to disclose.