Serine protease inhibitor Kazal type 1(SPINK1) downregulates E-cadherin and induces EMT of hepatoma cells to promote hepatocellular carcinoma metastasis via the MEK/ERK signaling pathway

Objective To investigate serine protease inhibitor Kazal type 1(SPINK1) expression and its influence on the prognosis of human hepatocellular carcinoma(HCC) and to explore the underlying molecular mechanisms involved. Methods Eighty patients with HCC who underwent curative resection were followed-up with a median observation time of 58.6 months.SPINK1expression was detected in the primary HCC samples by immunohistochemistry . Its role in tumor invasion and metastasis was evaluated in vitro by gene silence using siRNA-mediated approach, rSPINK1 and U0126(an inhibitor of MEK/ERK). The proteins in the MEK/ERK signaling pathway were detected by Western blotting. Results Patients expressing high levels of SPINK1showed poor overall survival (P < 0.0001) and recurrence-free survival (P < 0.001)compared with those of patients with low levels of SPINK1. SPINK1 suppression resulted in reduced cell migrationand invasion. SPINK1 overexpression was significantly associated with increased cell migrationand invasion in vitro. Furthermore, SPINK1 promoted cancer cells motility and epithelial-mesenchymal transition(EMT) via the mitogen-activated protein kinase kinase(MEK)/extracellular regulated kinase(ERK) pathway,resulting in increased vimentin expression and decreased E-cadherin expression. Conclusions Based on our results, SPINK1 might be an oncogene that induces EMT via the MEK/ERK pathway and a potential target for HCC therapy.