Document Type : Original Article
Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Autophagy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
Autophagy Research Center, Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Objective: Endoplasmic reticulum-metallopeptidase 1 (ERMP1) is involved in cellular response to oxidative stress.
However, its functional role in proliferation and progression of cancer cells remains unknown. The focus of this study
was to investigate the molecular-mechanisms in which ERMP1 modulates the proliferation and progression of colorectal
cancer (CRC) cells under normal and environment stress conditions.
Materials and Methods: In this experimental study, ERMP1 expression was evaluated using reverse transcriptionquantitative
polymerase chain reaction (RT-qPCR) in CRC cells. ERMP1 was knocked down using lentiviral transduction
of ERMP1-specific shRNA into HCT116 cells. ERMP1 was also upregulated using lipofectamine transfection of
ERMP1-overexpressing vector into SW48 cells. To evaluate the role of ERMP1 in the cellular and environmental stress
conditions, ERMP1-downregulated cells were exposed to stressful conditions including starvation, serum free medium,
and treatment with redox or chemotherapy agents for 72 hours. The expression of AKT, p-AKT, phospho-mammalian
target of rapamycin (p-mTOR), β-catenin, p-β-catenin, E-cadherin, and Glucose-regulating protein 78 (GRP78) proteins
was evaluated by western blotting. The expression of ERMP1, CYCLIN D, and c-MYC was evaluated by RT-qPCR. The
cell surface localization of GRP78, cell cycle distribution, and apoptosis were determined by Flow cytometry.
Results: ERMP1 knock-down reduced the cellular proliferation, inactivated the PI3K/AKT pathway, prompted the
G1 arrest, and attenuated the free β-catenin and CYCLIN D expression. Opposite results were obtained in ERMP1-
overexpressed cells. Knock-down of ERMP1 also reduced the GRP78 localization at the cell surface. Various
environmental stress conditions differently affected the ERMP1-downregulated cells.
Conclusion: ERMP1 functioned as an oncogene in CRC cells by promoting malignant characteristics. The
phosphoinositide 3-kinases (PI3K)/AKT/β-catenin pathway and localization of GRP78 were closely related to the effects
of ERMP1. Consequently, ERMP1 might be regarded as a promising target in therapeutic strategies related to CRC.