UCHL1 Promotes Chemoresistance to 5-Fluoruracil Based Adjuvant Chemotherapy and is a Prognostic Marker for Stage II Colon Cancer Patients

Abstract

Background: 5-Fluoruracil based adjuvant chemotherapy after radical resection is recommended for stage II colon cancer patients with high risk of recurrence. Up to now, novel biomarkers still needed for better stratification for improving prognosis. Methods: Here we report that UCHL1 is an independent prognostic factor for stage II colon cancer patients and promotes chemoresistance both in vitro and in vivo. Results: Our study indicated that UCHL1 is significant up regulated in 96 pairs of stage II colon cancer patients who received postoperative 5-FU based chemotherapy. Stage II colon cancer patients with high UCHL1 expression showed high recurrence rate after chemotherapy. Multivariate Cox regression analysis showed that UCHL1 is an independent prognostic factor for overall survival (P=0.008) and disease-free survival (P=0.001). 5-FU based chemoresistance is examined in colon cancer cell lines (RKO and LoVo) with down regulation of UCHL1 by cytotoxicity test. Down regulation of UCHL1 exhibited decreased cell viability, elevated cell apoptosis rate, increased G2/M-phase and elevated level of cleaved caspase 3 and PARP when treated with 5-FU. Furthermore, the results in xenograft model are consistent with results in vitro.Conclusions: UCHL1 potentially contributing to identify recurrence risk and predict the benefit for postoperative 5-FU based adjuvant chemotherapy in stage II colon cancer patients.