307P - G-CSF induces production of Bv8 in murine bone marrow neutrophils and promotes tumor growth and angiogenesis of U14 murine cervical cancer cell line

Abstract

Background: To investigate the effect of G-CSF inducing murine bone marrow neutrophils Bv8 production in vitro and its effect of promoting tumor growth and angiogenesis of U14 murine cervical cancer cell line in vivo. Methods: Naïve murine bone marrow neutrophils were separated and cultured in vitro and randomly divided into four groups: control group, G-CSF 50ng/ml stimulation group, G-CSF 50ng/ml + DMSO group and G-CSF 50ng/ml + PD98059 (ERK signal pathway inhibitor) 20μmol group. RT-PCR method was used to evaluate the mRNA level of Bv8 of neutrophils. Western blot was applied to test the phosphorylation levels of ERK pathway in neutrophils. In the animal co-inoculating experiment, U14 cervical cancer cell line and mouse bone marrow neutrophils were co-inoculated into mice with the use of G-CSFR and anti-Bv8 antibody to interfere the G-CSF and Bv8. The tumor burden and angiogenesis were calculated. Immunohistochemical staining was used to detect the microvessel density. Results: Compared with control group, the administration of G-CSF enhanced the mRNA expression of Bv8 (P=0.0050); The p-ERK levels in neutrophils was increased (P=0.0067). After the PD98059 was added, the mRNA expression of Bv8 and the p-ERK levels in neutrophils were decreased significantly than those in the G-CSF group (P=0.0089 and 0.098, respectively). The bone marrow neutrophils from the naïve mouse (NBM-PMN) could suppress tumor growth and angiogenesis, whereas the bone marrow neutrophils from the tumor-bearing mice (TBM-PMN) promoted tumor growth and angiogenesis of U14 cervical cancer cell line; both the G-CSFR plasmid and the anti-Bv8 antibody could attenuate the promotion of neutrophils. Conclusions: G-CSF induces the production of Bv8 in mice bone marrow neutrophils and the effect may be induced by the activation of ERK pathway. The U14 tumor environment could change the mouse bone marrow neutrophils to act in a way that favors tumor angiogenesis and tumor growth, and either to interfere G-CSF or Bv8 may reduce the pro-tumor function of mouse bone marrow neutrophils. Legal entity responsible for the study: Wu Xufeng Funding: None Disclosure: All authors have declared no conflicts of interest.