ObjectiveTo explore effect and mechanism of the carcinoma associated fibroblasts (CAFs) of breast cancer on growth and metastasis of breast cancer induced in nude mice by inoculation of CAFs and breast cancer cells. MethodsBreast cancer cell line of MDA-MB-231 (abbreviated as MDA), CAFs, and normal breast tissue fibroblasts (NFs) of the same breast cancer patient were collected, and mixed with normal saline (NS) or SDF-1 ligand blockers of four nitrogen heterocyclic fourteen alka (AMD3100, abbreviated as AMD) for inoculation of nude mice in vivo. According to the different combination, 36 nude mice were randomly divided into 6 groups:MDA+NS group, NFs+NS group, MDA+NFs+NS group, MDA+NFs+AMD group, MDA+CAFs+AMD group, and MDA+CAFs+NS group. Forty six days after the inoculation and feeding, volume of tumor, metastasis of lymph node, lung or liver were observed. In addition, level of plasma SDF-1 was tested by using ELISA method, and expressions of SDF-1 mRNA and protein in tumor specimens were detected by using real-time PCR and Western blot method respectively. ResultsExcept for NFs+ NS group, implanted tumor could be seen in nude mice of other 5 groups. In MDA+CAFs+NS group, the volume of tumor[(9.092±2.662) cm3], level of plasma SDF-1[(75.25±16.23) ng/L], and expression levels of SDF-1 mRNA (the median level was 14.714) and protein (the median level was 0.673). of tumor tissue were significantly greater or higher than those of the other 5 groups (P < 0.050). In addition, lymph node metastasis were found in 4 mice in MDA+CAFs+NS group, and 2 in MDA+NS group. The tumor metastasis of lung and liver was not found in all nude mice. ConclusionsCAFs can promote growth and lymph node metastasis of breast cancer, whose mechanism is related with SDF-1 secreted by CAFs and SDF-1/CXC chemokine receptor 4 (CXCR4), signal pathway.