Abstract B26: iNOS expression and lethal prostate cancer in patients with localized disease

Abstract

Abstract Inducible nitric oxide synthase (iNOS) has demonstrated both tumor-promoting and tumor-inhibiting effects in prostate cancer. However, the relationship between iNOS protein expression and long-term prostate cancer outcomes is unclear. We evaluated iNOS expression in tumor epithelia and stroma in 300 men with localized tumors diagnosed incidentally by transurethral resection of the prostate (TURP) in Sweden. In this extreme case-control design, cases (N=132) died of prostate cancer and controls (N=168) survived at least 8 years following diagnosis without death from prostate cancer or a competing cause. Immunohistochemistry was undertaken with a polyclonal rabbit anti-human NOS2 antibody (Abcam) and the Ventana (Roche) semi-automated staining system. Two observers individually scored the staining according to intensity and number of positive cells from 0-3. The median value across cores in each patient were then categorized as <1, >1-<2, and >2, separately for epithelial and stromal compartments. Odds ratios for lethal prostate cancer were estimated with logistic regression controlling for the matching factors (age, calendar year of diagnosis), as well as tumor stage, Gleason score, and percent tumor. iNOS was expressed by stromal-associated M1 macrophages and fibroblasts, as well as tumor cells. Gleason score was positively associated with both stromal and epithelial iNOS staining. In the stroma, there was no statistically significant association between iNOS expression and lethal prostate cancer after adjustment for clinical covariates. However, the odds of lethal prostate cancer increased with tumor expression of iNOS in the fully adjusted model. Compared to patients with the lowest category of iNOS expression, the odds ratios for lethal prostate cancer were 2.96 (95% CI: 1.26-6.96) for patients in the second category and 3.80 (95% CI: 1.45-9.97) for patients in the top category. These results suggest that iNOS may help to identify patients with aggressive prostate cancer at the time of diagnosis, or may be a therapeutic target. Given previously reported in vitro data suggesting that iNOS promotes proliferation of androgen-independent prostate tumors, future analyses will investigate association between iNOS expression and time to castration-resistant prostate cancer in this patient population. Citation Format: Jennifer R. Rider, Ann Erlandsson, Chirag Vyas, Sabina Davidsson, Jessica Carlsson, Swen-Olof Andersson, Ove Andren. iNOS expression and lethal prostate cancer in patients with localized disease [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B26.