Clinical significance of HuR expression, an mRNA-binding protein in non-small cell lung cancer (NSCLC)

Abstract

10098 Background: HuR is a nucleo-cytoplasmic shuttling protein that specifically binds to mRNA that has AU rich (ARE) sites at the 3’end and transports the RNA to the cytoplasm for protein translation. In addition to mRNA transportation, HuR plays a role in mRNA stabilization and protein translation. Preclinical studies have shown mRNA’s of several growth factors, cell-cycle regulators, and transcription-regulating proteins have ARE’s at the 3’end and bound by HuR. However, there has been reported no clinical data on HuR expression in NSCLC. Thus, in the present study, we assessed clinical significance of HuR expression in NSCLC. Patients and Methods: A total of 236 patients with completely resected p-stage I-IIIA, NSCLC, were reviewed, and HuR expression was evaluated immunohistochemically. Results (Table): HuR expression was seen in the nucleus and cytoplasm of tumor cells. Cytoplasmic HuR expression was positively correlated with tumor progression (p-stage, P<0.01), especially nodal metastasis, microvessel density (MVD), and COX-2 expression. Enhanced nuclear HuR expression was also correlated with tumor progression and COX-2 expression, but not with MVD. Positive cytoplasmic HuR expression was a significant factor to predict a poor prognosis in all patients (5-year survival rates: 85% for HuR-negative and 43% for HuR-positive patients; P<0.01) and in any p-stage/histology subset patients. Nuclear HuR expression status was also a significant prognostic factor in all patients, but not in all subsets. A multivariate analysis confirmed that cytoplasmic HuR status was an independent prognostic factor (hazard ratio [95% CI], 4.261 [2.109–8.609]; P<0.001). Conclusions: Cytoplasmic HuR expression was correlated with tumor progression, and was a significant and independent prognostic factor in correlation with enhanced COX-2 expression and increased tumor angiogenesis. [Table: see text] No significant financial relationships to disclose.