Abstract 5012: Nuclear expression of lysyl oxidase enzyme is an independent prognostic factor in rectal cancer patients

Abstract

Abstract Emerging evidence implies that the complex and seemingly paradoxical role of lysyl oxidase (LOX) in cancer may depend on its subcellular localization. LOX expression has been reported extracellularly, as well as intracellularly in both the cytoplasmic and nuclear compartments. In this study we analyze previously unreported LOX expression patterns in the nucleus of rectal cancer patient samples and determine the clinical significance of this expression. LOX expression was examined by immunohistochemistry in 137 primary rectal cancer patients who participated in the randomized Swedish rectal cancer trial of preoperative radiotherapy between 1987 and 1990. Location and expression of LOX protein were detected by confocal microscopy and Western blot in three colon cancer cell lines. LOX nuclear expression was high in normal mucosal and showed a significant decrease in primary rectal cancer (P<0.001). Furthermore, a significant increase was observed from primary cancer to lymph node metastasis (P<0.01). High nuclear LOX expression was correlated with a high rate of distant metastasis and total recurrence (P = 0.046, P = 0.048, respectively). It was also confirmed that LOX (50-kDa and 32-kDa isoforms) are located in the nucleus of in vitro colon cancer cells. High nuclear LOX expression was found in the metastatic cell line SW620 compared to the parental primary cancer cell line SW480. Radiotherapy had no effect on LOX expression and localization in cancer tissues as well as in in vitro culture. Moreover, multivariable analysis showed that high nuclear LOX expression correlated with poor overall survival (P = 0.003) and disease free survival (P = 0.006), independent of age, gender, TNM stage, differentiation and radiotherapy treatment. Nuclear LOX also correlated with other biological factors (such as NF-κB) known to be associated with patient survival suggesting a possible mechanism. Cytoplasmic LOX is high in primary cancer and metastasis compared with normal tissue, but not prognostic. So here we firstly proved the nuclear expression of LOX enzyme both in patient rectal cancer tissues and in in vitro colon cancer cells. The strong correlation of nuclear LOX expression to survival offers a promising prognostic biomarker in rectal cancer. Citation Format: Na Liu, Thomas R. Cox, Weiyingqi Cui, Gunnar Adell, Birgitta Holmlund, Janine T. Erler, Xiaofeng Sun. Nuclear expression of lysyl oxidase enzyme is an independent prognostic factor in rectal cancer patients. [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 5012.