CCR2 Expression Promotes Diffuse Large B Lymphoma Cell Survival and Invasion

Objective: Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma world wide. It is a phenotypically and genetically heterogeneous disease, accounting for 30-40% of all cases. 50%-70% of patients can be cured by the R-CHOP regimen, but nearly one-third of patients develop relapsed or refractory disease. CC chemokine receptor 2 (CCR2), the high affinity receptor of CC-Chemokine Ligand 2 (CCL2), which is the most representative of the CC chemokine family members, has be regarded to involve in tumor growth, angiogenesis, epithelial mesenchymal transition, metastasis and immune escape etc.. In recent years, the role and mechanism in DLBCL has not been reported yet. Our preliminary study showed that high expression of CCR2 was correlated with clinicopathological characteristics, and an adverse prognostic factor for overall survival (OS) and progression-free survival (PFS) of DLBCL patients. The purpose of this study is to investigate the role of CCR2 expression in DLBCL cells proliferation and migration by in vitro and in vivo.

Methods: CCR2 expression were analyzed in human DLBCL cell lines (SUDHL-2, SUDHL-4, SUDHL-6, OCI-Ly8 and OCI-Ly10) by Western blot (WB). SUDHL-2 and OCI-Ly8 cells were incubated with CCR2 antagonist SC-202525 (Santa Crutz Biotechnology), and control cells were left untreated. The proliferation, migration, apoptosis and signaling pathway were detected by CCK8, transwell, flow cytometry (FC) and WB, respectively in vitro. The engraftment, tumor growth, dissemination and survival time were observed in BALB/c nude mice.

Results: CCR2 were expressed in all human DLBCL cell lines (relative CCR2 expression was higher in SUDHL-2, SUDHL-4 and OCI-Ly8 than in SUDHL-6 and OCI-Ly10 cell lines). Blockade of CCR2 expression signaling with CCR2 antagonist inhibited tumor cell proliferation, migration and anti-apoptosis ability. The signaling involved in the proliferation and migration of DLBCL cells by activating PI3K/Akt signaling pathway, and induced apoptosis through activation of P38MARK signaling pathway. Expression of CCR2 was also associated with increased engraftment, tumor growth and dissemination, and decreased survival time in xenograft mice. Furthermore, administration of CCR2 antagonist decreased tumor growth and dissemination of DLBCL cells, and increased survival time in the xenograft model.

Conclusions: Our study demonstrates that CCR2 plays an important role in the development of DLBCL by stimulating cell proliferation, migration and anti-apoptosis. The inhibition of CCR2 may, therefore, be a potential target for anticancer therapy in DLBCL.