Overexpression of nuclear NHERF1 in advanced colorectal cancer: association with hypoxic microenvironment and tumor invasive phenotype.

Over 57% of colorectal cancer (CRC) patients have regional or distant spread of their disease at the time of diagnosis. Despite recent advances, there is a compelling need to better characterize prognostic markers for advanced CRC. The present study investigates protein expression of NHERF1, HIF-1α and TWIST1 and their relationship in distant normal mucosa (DNM), tumor (T) and adjacent normal mucosa (ANM), lymph node metastasis (LNM) and liver metastasis (LM), determining their role as potential markers in advanced stages of human CRC. Overexpression of nuclear NHERF1 was shown in 47% of tumors, which exhibited a significant association with poor histological grade (P=0.0346). Nuclear NHERF1 showed a higher expression in T, LNM and LM than both DNM (P<0.0001) and ANM (P<0.05). Nuclear HIF-1α was significantly higher in T, LNM and LM than DNM and ANM (P<0.05, P<0.001, P<0.0001, respectively). A positive correlation between nuclear NHERF1 and nuclear HIF-1α was found in LNM (r=0.331, P=0.020), where an extended co-localization of the two proteins was demonstrated. TWIST1 was more expressed in T than DNM and ANM (P<0.0001) and was higher in T than LNM and LM (P<0.0001). Moreover, nuclear NHERF1 was directly correlated to TWIST1 (r=0.339, P=0.015) in T samples, where a high co-expression of the two proteins was demonstrated both in no longer polarized epithelial cells and in invasive mesenchymal elements adjacent to hypoxic and perinecrotic colonic areas. Overall, nuclear NHERF1 expression was associated with poorer differentiation grade and with higher expression both of HIF-1α in lymphatic metastasis and TWIST1 in invasive front of tumor. Our results support the oncogenic role of NHERF1 and promote nuclear NHERF1 as a potential new biomarker of advanced CRC.