Granulin epithelin precursor promotes colorectal carcinogenesis by activating MARK/ERK pathway

Yi Pan,Hui Li,Siu Tim Cheung,Wei Kang,Joanna Hung Man Tong,Raymond Wai Ming Lung,Ka Fai To,Ka Yee Tin,Tony Wing Chung Mak,Anthony Wing Hung Chan,Feng Wu,Simon Siu Man Ng

doi:10.1186/s12967-018-1530-7

Yi Pan, Hui Li + Show 10 more

Open Access

https://doi.org/10.1186/s12967-018-1530-7

Copy DOI

Abstract

BackgroundGranulin epithelin precursor (GEP) is reported to function as a growth factor stimulating proliferation and migration, and conferring chemoresistance in many cancer types. However, the expression and functional roles of GEP in colorectal cancer (CRC) remain elusive. The aim of this study was thus to investigate the clinical significance of GEP in CRC and reveal the molecular mechanism of GEP in CRC initiation and progression.MethodsThe mRNA expression of GEP in CRC cell lines were detected by qRT-PCR. The GEP protein expression was validated by immunohistochemistry in tissue microarray (TMA) including 190 CRC patient samples. The clinicopathological correlation analysis were achieved by GEP expression on TMA. Functional roles of GEP were determined by MTT proliferation, monolayer colony formation, cell invasion and migration and in vivo studies through siRNA/shRNA mediated knockdown assays. The cancer signaling pathway identification was acquired by flow cytometry, western blot and luciferase activity assays.ResultsThe mRNA expression of GEP in CRC was significantly higher than it in normal colon tissues. GEP protein was predominantly localized in the cytoplasm and most of the CRC cases demonstrated abundant GEP protein compared with non-tumorous tissues. GEP overexpression was associated with non-rectal location, advanced AJCC stage, regional lymph node and distant metastasis. By Kaplan–Meier survival analysis, GEP abundance served as a prognostic marker for worse survival in CRC patients. GEP knockdown exhibited anti-cancer effect such as inhibiting cell proliferation, monolayer colony formation, cell invasion and migration in DLD-1 and HCT 116 cells and decelerating xenograft formation in nude mice. siGEP also induced G1 cell cycle arrest and apoptosis. Luciferase activity assays further demonstrated GEP activation was involved in MAPK/ERK signaling pathway.ConclusionIn summary, we compressively delineate the oncogenic role of GEP in colorectal tumorigenesis by activating MAPK/ERK signaling pathway. GEP might serve as a useful prognostic biomarker and therapeutic target for CRC.

Highlights

Granulin epithelin precursor (GEP) is reported to function as a growth factor stimulating proliferation and migration, and conferring chemoresistance in many cancer types
Granulin epithelin precursor (GEP), known as progranulin, acrogranin, proepithelin, and GP88/PC-cell derived growth factor, is a secreted glycoprotein composed of 7.5 repeats of cysteine-rich motif [6, 7]
GEP is overexpressed in CRCGEP mRNA expression was up-regulated in 6/8 colorectal cancer (CRC) cell lines compared with the normal colon epithelium by quantitative real-time polymerase chain reaction (qRT-PCR) (Fig. 1a)

Summary

Introduction

Granulin epithelin precursor (GEP) is reported to function as a growth factor stimulating proliferation and migration, and conferring chemoresistance in many cancer types. Granulin epithelin precursor (GEP), known as progranulin, acrogranin, proepithelin, and GP88/PC-cell derived growth factor, is a secreted glycoprotein composed of 7.5 repeats of cysteine-rich motif [6, 7]. It is expressed in immune cells [8, 9], neurons [10], epithelial cells [11] and chondrocytes [12], mediating wound healing, neurodegeneration and cartilage development [7, 10,11,12]. Functional studies reveals GEP acts as a growth factor to stimulate proliferation and migration, and confer chemoresistance in many types of cancers including breast cancer [16, 17], ovarian cancer [18, 19], liver cancer [20, 21] and bile duct cancer [22]

Objectives

Methods

Results

Conclusion