CCL2-CCR2 axis promotes metastasis of nasopharyngeal carcinoma by activating ERK1/2-MMP2/9 pathway

Jing Yang,Weixiong Xia,Jinna Chen,Yanqun Xiang,Hu Liang,Xin-Yuan Guan,Yanfang Ye,Changqing Xie,Xing Lv,Yahui Yu,Chen Jiang,Tingting Zeng,Liangru Ke,Xiang Guo

doi:10.18632/oncotarget.6695

Abstract

Distant metastasis remains the major failure of nasopharyngeal carcinoma (NPC). In this study, the roles of chemokine C-C motif ligand 2 (CCL2), and its receptor chemokine C-C motif receptor type 2 (CCR2) on NPC metastasis were investigated. Serum CCL2 and CCL2/CCR2 expression level were remarkably increased in NPC patients compared to non-tumor patients by ELISA and IHC analyses. High expressions of CCL2/CCR2 were significantly associated with NPC metastasis and poor overall survival (OS). High expression of CCR2 is an independent adverse prognostic factor of OS and distant metastasis free survival (DMFS). Overexpressions of CCL2 and CCR2 were detected in high-metastatic NPC cell lines. Upregulating CCL2 and CCR2 respectively in low-metastatic NPC cell lines could promote cell migration and invasion, and exogenous CCL2 enhanced the motility in CCR2-overexpressing cells. On the other hand, downregulating CCL2 and CCR2 respectively in high-metastatic NPC cell lines by shRNA could decrease cell migration and invasion. However, exogenous CCL2 could not rescue the weaken ability of motility of CCR2-silencing cells. In nude mouse model, distant metastasis was significantly facilitated in either CCL2-overexpressing or CCR2-overexpressing groups, which was more obvious in CCR2-overexpressing group. Also, distant metastasis was considerably inhibited in either CCL2-silencing or CCR2-silencing groups. Dual overexpression of CCL2/CCR2 could activate extracellular signal-regulated kinase (ERK1/2) signaling pathway, which sequentially induced matrix metalloproteinase (MMP) 2 and 9 upregulations in the downstream. In conclusion, CCL2-CCR2 axis could promote NPC metastasis by activating ERK1/2-MMP2/9 pathway. This study helps to develop novel therapeutic targets for distant metastasis in NPC.

Highlights

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in Southeast Asia and southern China with incidences reported as 15–50 per 100,000 [1,2,3].Non-keratinizing carcinoma, the major histologic form of NPC, dominates in these high-incidence areas, with a feature of high distant metastasis rate at the time of diagnosis [4] or after initial treatment [5]
C–C motif ligand 2 (CCL2) and C motif receptor type 2 (CCR2) are frequently upregulated in NPC tissues and highly metastatic NPC cell lines, and CCL2 is remarkably increased in the sera of NPC patients
The results found that high expression level of CCL2 was significantly associated with N stage (P = 0.005), and high expression level of CCR2 was significantly associated with distant metastasis (P = 0.032) and prognosis (P = 0.001, Table 1)

Summary

Introduction

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in Southeast Asia and southern China with incidences reported as 15–50 per 100,000 [1,2,3].Non-keratinizing carcinoma, the major histologic form of NPC, dominates in these high-incidence areas, with a feature of high distant metastasis rate at the time of diagnosis [4] or after initial treatment [5]. CCL2 belongs to the superfamily of secreted proteins of chemokines involved in immunoregulatory and inflammatory processes. It is a monomeric polypeptide contains a signal peptide of 23 amino acids and primarily secreted by monocytes, macrophages and dendritic cells [8]. CCL2 has been implicated in etiopathogeneses of several non-neoplastic diseases including diabetes mellitus, rheumatoid arthritis, and certain neuronal degeneration [9,10,11]. It was reported as an important promoter in the development and progression of many types of tumors by stimulating cell proliferation and migration directly and/or indirectly [12]. One of our previous studies in NPC had shed a light on the relationship between the serum CCL2 (sCCL2) level of patients and their prognosis, suggesting that high sCCL2 level predicts bone invasion, posttreatment distant metastasis and poor overall survival in NPC patients [23]

Methods

Results

Conclusion