The elevated level of CXCR4 is correlated with nodal metastasis of human breast cancer

CXCR4, the receptor for stromal cell-derived factor-1(SDF-1), belongs to the chemokine receptor family and has been shown to play an important role in regulating the directional migration of breast cancer cells to sites of metastasis. In the present study, we evaluated the expression of CXCR4 and its association with pathological features and clinical outcome in human breast cancer. Expression of CXCR4 in eight breast cancer cell lines and breast cancer tissues was investigated using conventional PCR. Levels of CXCR4 transcript and protein were examined in human breast cancer tissues (n=120) and corresponding normal tissues (n=32) using real-time quantitative PCR and immunohistochemistry, respectively. The level of CXCR4 expression was analyzed against tumour types, grade, nodal status, recurrence, metastasis, and survival over a median 120 month follow-up period. The expression of CXCR4 was detected in all breast cancer cell lines examined, as well as in breast cancer tissues and breast normal tissues. Breast cancer tissues highly expressed CXCR4 compared with corresponding normal tissues (P=0.029). The level of CXCR4 expression showed a significant difference between node-positive group and node-negative group (19±13 vs. 49.7±9, respectively, P=0.03). The level of CXCR4 expression was marginal, yet statistically insignificant, higher in tumours from patients with metastatic disease compared with those who remained disease free. No correlation was seen between levels of CXCR4 and the overall survival, although at higher levels of CXCR4 linked to shorter disease free survival (113.0 vs. 136.7 months in patients with low CXCR4, P=0.14, Cox proportional test). The level of CXCR4 expression is significantly correlated with lymph node metastasis. The elevated levels of CXCR4 suggest that the patient has high possibility of lymph node metastasis. CXCR4 may be a useful prognostic indicator and a potential therapeutic target in cancer therapies in patients with breast cancer.