MicroRNA-375-3p Suppresses Upper Tract Urothelial Carcinoma Cell Migration and Invasion via Targeting Derlin-1

SIMPLE SUMMARY: The Derlin-1 protein, encoded by DERL1, is located in the endoplasmic reticulum membrane and is responsible for the unfolded protein response. Derlin-1 has recently drawn lots of attention with regard to cancer pathogenesis. The purpose of this study is to examine its role and molecular mechanism in upper tract urothelial carcinoma (UTUC). The protein levels of Derlin-1 in human UTUC specimens are observed by immunohistochemistry. Derlin-1 overexpression is evidently associated with cancer stage, distant metastasis, recurrence, and poor prognosis in patients with UTUC. In an in vitro study, the knockdown of Derlin-1 represses, while over-expression of Derlin-1 increases migration and invasion of UTUC cells significantly. We identify the microRNA-375-3p (miR-375-3p) as one of the potential candidate microRNAs and then examine the relationship between Derlin-1 and miR-375-3p. The dual-luciferase reporter assay confirms that miR-375-3p directly targets Derlin-1. Furthermore, we reveal that miR-375-3p modulate Derlin-1 and epithelial–mesenchymal transition (EMT) marker protein levels. However, the above effects are reversed by the restoration of Derlin-1. Our study clarifies that miR-375-3p represses invasion and migration by directly targeting Derlin-1 and regulating the expression of EMT-associated proteins in UTUC cells, suggesting Derlin-1 may act as a useful predictor of prognosis and that both Derlin-1 and miR-375-3p could be potential therapeutic targets in UTUC. ABSTRACT: Little is known regarding the molecular characterization of upper tract urothelial carcinoma (UTUC). Novel therapeutic targets and prognostic predictors are imminent. In the present study, we aim to examine the oncogenic function and molecular mechanism of Derlin-1 in UTUC. Derlin-1 overexpression is significantly associated with poor prognosis in patients with UTUC. In vitro, knockdown or over-expression of Derlin-1 markedly regulated UTUC cell invasion and migration. We further discovered miR-375-3p suppresses cell invasion and migration by inversely regulating Derlin-1 and blocking EMT in UTUC cells. Taking this together, miR-375-3p functions as a tumor suppressive microRNA by directly targeting Derlin-1 and blocking epithelial–mesenchymal transition (EMT) in UTUC.