Expression and Clinicopathological Implications of the Vitamin C Transporters SVCT-1 and SVCT-2 in Colon Cancer

Abstract

Most of the colon cancer patient tumors progress to metastases, despite undergoing surgical resection or adjuvant chemotherapy. Predicting which patients will progress to metastases has been extremely challenging. There is an urgent need to identify early novel prognostic biomarkers that can early on predict the patient outcome. Vitamin C has been shown to have a pro-oxidant effect on cancer that enhances tumor growth and survival. Vitamin C is transported into mammalian cells via two isoforms of sodium-dependent vitamin C transporters (SVCTs), SVCT1 and SVCT2. The expression and clinical implications of SVCTs in tumor tissues could help us investigate its prognostic value in predicting patient outcome. In this report, we performed immunohistochemistry to determine SVCT1 and SVCT2 expression on primary tumors of 178 colon cancer patients. Colon cancer cells selectively expressed SVCT2 but not SVCT1. Moreover, poorly differentiated and metastatic tumors correlated with higher SVCT2 expression. Furthermore, increased SVCT2 expression was associated with shorter progression-free survival in patients with no or little lymph node invasion. We confirmed that SVCT2 could be an early stage prognostic biomarker that can predict colon cancer disease progression and survival.