Epidermal growth factor induces HCCR expression via PI3K/Akt/mTOR signaling in PANC-1 pancreatic cancer cells

Zekuan Xu,Jin W Kim,Guoxin Zhang,Jiakai Jiang,Zhihong Zhang,Yang Yang,Yi Zhang,Ruihua Shi,Zuhu Huang,Bo Hao

doi:10.1186/1471-2407-10-161

Abstract

BackgroundHuman cervical cancer oncoprotein 1 (HCCR-1), reported as a negative regulator of p53, is over-expressed in a variety of human cancers. However, it is yet unknown whether HCCR-1 plays any role in pancreatic cancer development. The aim of this study was to investigate the effect of epidermal growth factor on the expression of HCCR in pancreatic cancer cells, and to explore if PI3K/Akt/mTOR signaling pathway mediated this expression.MethodsA polyclonal antibody against HCCR protein was raised by immunizing Balb/c mice with the purified recombinant protein pMBPc-HCCR. Tissue samples were constructed on a tissue chip, and the expression of HCCR was investigated by immunohistochemistry assay and Western blotting. Pancreatic cell line, PANC-1 cells were stably transfected with plasmids containing sense-HCCR-1 fragment and HCCR siRNA fragment. MTT and transwell assay were used to investigate the proliferation and invasion of stable tansfectants. The specific inhibitor of PI3K and mTOR was used to see if PI3K/mTOR signal transduction was involved in the induction of HCCR gene expression. A Luciferase assay was used to see if Akt can enhance the HCCR promoter activity.ResultsHCCR was up-regulated in pancreatic tumor tissues (mean Allred score 4.51 ± 1.549 vs. 2.87 ± 2.193, P < 0.01), especially with high expression in poorly differentiated pancreatic cancer. The growth of cells decreased in HCCR-1 siRNA transfected cells compared with vector transfectants. The number of invasion cells was significantly lower in HCCR-1 siRNA transfected cells (24.4 ± 9.9) than that in vector transfectants (49.1 ± 15.4). Treatment of PANC-1 cells with epidermal growth factor increased HCCR protein level in a dose- and time-dependent manner. However, application of LY294002 and rapamycin caused a dramatic reduction of epidermal growth factor-induced HCCR expression. Over-expression of exogenous constitutively active Akt increased the HCCR promoter activity; in contrast, dominant negative Akt decreased the promoter activity.ConclusionsEGF-induced HCCR-1 over-expression is mediated by PI3K/AKT/mTOR signaling which plays a pivotal role in pancreatic tumor progression, suggesting that HCCR-1 could be a potential target for cancer therapeutics.

Highlights

Human cervical cancer oncoprotein 1 (HCCR-1), reported as a negative regulator of p53, is overexpressed in a variety of human cancers
To investigate whether Human cervical cancer oncogene (HCCR)-1 plays any role in pancreatic cancer development, we firstly examined the pancreatic cancer cell growth in vitro after transfecting PANC-1 cells with HCCR-1 expressing DNA constructs
Our result reveals that HCCR-1 enhances the growth of PANC-1 cells in vitro by 1.5 fold over 3-day incubation period (Fig. 2B)

Summary

Introduction

Human cervical cancer oncoprotein 1 (HCCR-1), reported as a negative regulator of p53, is overexpressed in a variety of human cancers It is yet unknown whether HCCR-1 plays any role in pancreatic cancer development. A large number of Recent molecular investigations have elucidated complex genetic mechanisms of cancer that especially involve multiple signal transduction pathways. These findings enable us to develop molecular medicines targeting specific genetic molecules in the pathways. Sor genes play crucial roles in the development and progression of the disease Many of these dysfunctioning molecules comprise signaling pathways, which indicates that cancer is a signaling disorder. This extent of dependence upon aberrant signaling systems in cancer implies that shutting down the signaling would cause the cancer to vanish

Objectives

Methods

Results

Discussion

Conclusion