Knocking-down of CREPT prohibits the progression of oral squamous cell carcinoma and suppresses cyclin D1 and c-Myc expression.

Juntao Ma,Lei Zhang,Xiangpan Kong,Rongfa Bu,Yipeng Ren,Yueyi Shi,Tong Wang,Aamir Ahmad

doi:10.1371/journal.pone.0174309

Abstract

BackgroundAs a regulator essential for many cell cycle-related proteins, the robust expression of Cell cycle-Related and Expression-elevated Protein in Tumor (CREPT) implicates a poor diagnosis of endoderm and mesoderm-derived tumors. Whether CREPT plays the same role in the tumorigenesis derived from ectodermal tissues remains elusive.MethodsTo explore the role of CREPT in ectoderm-derived tumors, cells from 7oral squamous cell carcinoma (OSCC) lines and 84clinical OSCC samples were exploited in this study. Quantitative PCR, Western blot assay and immunohistochemistry were applied in the evaluation of CREPT, cyclin D1 and c-Myc expression. Knocking-down of CREPT was performed by lentivirus delivering specific shRNA of CREPT. The effects of CREPT on OSCC were examined by cell proliferation, colony formation, apoptosis, cell migration and xenograft implantation experiments.ResultsCompared with human normal oral keratinocytes, OSCC cell lines showed a significantly elevated expression of CREPT in both mRNA and protein levels. Consistently, samples from OSCC patients also exhibited a noticeably stronger CREPT expression than the noncancerous samples. In contrast, knocking down of CREPT in OSCC cell lines significantly reduced proliferation, colony formation and migration as well as the expression of cyclin D1 and c-Myc, but promoted apoptosis. Statistical analysis also suggested that CREPT expression was significantly correlated with the T and N classification of OSCC. Furthermore, CAL27 mouse xenograft model confirmed that down-regulation of CREPT prohibited cyclin D1 and c-Myc expression, through which decreased the in vivo tumor growth, but increased the survival ratio of hosts.ConclusionIn OSCC cell lines, up-regulated CREPT expression enhanced cell proliferation, migration and cell cycle as well as promoted cyclin D1 and c-Myc expression as it did in endoderm and mesoderm-origin tumors. Our study strongly suggests that CREPT could be used as a marker for the OSCC prognosis and might work as a potential target in future OSCC therapy.

Highlights

As the most widely spread oral tumor, OSCC accounts for more than 90% of oral neoplasms and affects about 270,000 people throughout the world
Statistical analysis suggested that cycle-Related and Expression-elevated Protein in Tumor (CREPT) expression was significantly correlated with the T and N classification of OSCC
In OSCC cell lines, up-regulated CREPT expression enhanced cell proliferation, migration and cell cycle as well as promoted cyclin D1 and c-Myc expression as it did in endoderm and mesoderm-origin tumors

Summary

Introduction

As the most widely spread oral tumor, OSCC accounts for more than 90% of oral neoplasms and affects about 270,000 people throughout the world. Similar to cyclin D1, the expression of a series of cell cycle-related factors, such as cyclin E, CDK2, CDK4 and CKD6, are promoted by CREPT in the same manner [9]. Besides the enhancement on tumorigenesis, CREPT plays a critical role in the activation of peripheral T cells, keratinocyte differentiation and metastasis by regulating cell cycle-related genes [11]. Since all these effector genes down-stream to CREPT participate in a wide array of biological processes, the interference on CREPT expression is suggested to be an approach regulating multiple cell behaviors and functions [12,13,14,15]. Whether CREPT plays the same role in the tumorigenesis derived from ectodermal tissues remains elusive

Methods

Results

Conclusion