The CXCL12/CXCR7 signalling axis promotes proliferation and metastasis in cervical cancer.

C-X-C chemokine receptor 7 (CXCR7), a novel receptor of C-X-C motif chemokine ligand 12 (CXCL12), is associated with the occurrence and metastasis of various malignant tumours. However, the role, function and underlying mechanisms of CXCR7 expression in cervical cancer remain undefined. The expression level of CXCR7 was evaluated in cervical cancer samples by immunohistochemistry and real-time PCR analyses. Western blot analysis was used to examine the expression level of CXCR7 in cervical cancer cell lines. HeLa cells were genetically silenced or pharmacologically inhibited for CXCR7 or CXCR4. Transwell and CCK-8 assays were used to examine cell migration and proliferation. The expression levels of MMP2, MMP9, TIMP-1 and TIMP-2 in HeLa cells were assessed by western blot or real-time PCR. HeLa cells silenced for CXCR7 were subcutaneously injected into nude mice to form tumours. The expression of CXCR7 in nude mice was investigated by immunohistochemical staining. Tumour volumes and weights were measured. The in vivo expression levels of MMP2, MMP9, TIMP-1 and TIMP-2 were determined by western blot analysis and real-time PCR. CXCR7 was overexpressed in cervical cancer tissues and cell lines. CXCL12 was highly expressed in cervical cancer lines. CXCR7 silencing or CCX733 treatment rather than CXCR4 silencing or AMD3100 treatment suppressed the proliferation, migration and invasion of cervical cancer cells stimulated by CXCL12. In a xenograft tumour model, CXCR7 silencing or CCX733 treatment inhibited the volumes and weights of xenograft tumours. In addition, downregulation of CXCR7 decreased the expression levels of MMP2 and MMP9 but increased the expression levels of TIMP-1 and TIMP-2 in vivo. These data support the finding that the downregulation of CXCR7 suppresses the proliferation and metastasis of cervical cancer cells. Inhibition of CXCR7 may be a potential targeted therapy for cervical cancer.