Abstract 5018: Immunohistochemical expression of lysyl oxidase in prostate cancer

Abstract

Abstract Background: Lysyl oxydase (LOX) is a family of enzymes involved in catalyzing the cross-linking of collagen and elastin in the extracellular matrix, playing a crucial role in the building, strengthening and maintenance of tissues. Changes in its expression have been associated with many diseases. In oncology, these changes have been implicated in every step of tumor progression in different organs, with currently little existing data on prostate. The aim of this study is to analyze the nuclear expression of LOX in prostate tumor epithelial cells using a prostate cancer tissue array cohort. Design: PCa tumor samples were obtained from an outcome-based TMA set (5 tissue microarray blocks with 200 paired recurrence (R) and non-recurrence (NR) cases, 400 subjects total, each with quadruplicate 0.6 mm in diameter cores) from the Cooperative Prostate Cancer Tissue Resource (CPCTR). Each case was obtained from a PSA-recurrence subject matched to a non-recurrence subject based on age; race; interval since prostatectomy; Gleason sum-score and pTNM stage. All had at least 5 years follow up, and cases with known metastases were excluded. TMA sections were incubated with rabbit polyclonal anti-human LOX antibody (1:800, NB100-2527, Novus Biologicals) using the Bond™ polymer refine detection HRP (Leica Biosystems, DS9800). Nuclear LOX staining was scored semi-quantitatively as follows: 0, negative; 1+, weak; 2+, moderate; and 3+, strong. Percentage of positively stained cells at each intensity level was recorded to obtain a final h-score The Wilcoxon signed-rank test was used for the statistical analysis of the pair-matched dataset to assess the 2 groups (R vs. NR) for differences in LOX expression. Results: Data generated was available in 168 complete pairs. The Wilcoxon signed rank test showed no statistically significant differences for the h-score between the two groups (R vs. NR) (median = 2.15625 [range 0-3] vs. median = 2.2583333335 [range 0-3], p = 0.24604). Conclusions: The role of LOX in prostate cancer has not been fully established, and inhibitory and stimulatory effects have been reported. This is the first study in a case-control cohort evaluating the expression of LOX in prostate cancer. Based on our results we are now completing the analysis comparing expression of LOX in normal epithelium and cancer associated stroma. Citation Format: Virgilia Macias, Santiago Delgado, Andre A. Kajdacsy-Balla. Immunohistochemical expression of lysyl oxidase in prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5018.