Serum Nardilysin, a Surrogate Marker for Epithelial-Mesenchymal Transition, Predicts Prognosis of Intrahepatic Cholangiocarcinoma after Surgical Resection.

Abstract

Few studies have investigated prognostic biomarkers in patients with intrahepatic cholangiocarcinoma (ICC). Nardilysin (NRDC), a metalloendopeptidase of the M16 family, has been suggested to play important roles in inflammation and several cancer types. We herein examined the clinical significance and biological function of NRDC in ICC.<b>Experimental Design:</b> We measured serum NRDC levels in 98 patients with ICC who underwent surgical resection in two independent cohorts to assess its prognostic impact. We also analyzed <i>NRDC</i> mRNA levels in cancerous tissue specimens from 43 patients with ICC. We investigated the roles of NRDC in cell proliferation, migration, gemcitabine sensitivity, and gene expression in ICC cell lines using gene silencing. High serum NRDC levels were associated with shorter overall survival and disease-free survival in the primary (<i>n</i> = 79) and validation (<i>n</i> = 19) cohorts. A correlation was observed between serum protein levels and cancerous tissue mRNA levels of <i>NRDC</i> (Spearman <i>ρ</i> = 0.413; <i>P</i> = 0.006). The gene knockdown of <i>NRDC</i> in ICC cell lines attenuated cell proliferation, migration, and tumor growth in xenografts, and increased sensitivity to gemcitabine. The gene knockdown of <i>NRDC</i> was also accompanied by significant changes in the expression of several epithelial-mesenchymal transition (EMT)-related genes. Strong correlations were observed between the mRNA levels of <i>NRDC</i> and EMT-inducing transcription factors, <i>ZEB1</i> and <i>SNAI1</i>, in surgical specimens from patients with ICC. Serum NRDC, a possible surrogate marker reflecting the EMT state in primary tumors, predicts the outcome of ICC after surgical resection.