Differential Expression of CXCR4 Is Associated with the Metastatic Potential of Human Non–Small Cell Lung Cancer Cells

Purpose: To evaluate the relation between CXCR4 expression and the presence of metastatic disease in human non–small cell lung cancer (NSCLC) patients and investigate whether modulation of CXCR4 expression could serve as a potential pathway in preventing metastasis of NSCLC. Experimental Design: CXCR4 expression in 36 patients with NSCLC and 10 normal lung tissues was detected by real-time PCR and immunohistochemistry. CXCR4 expression in two human NSCLC clones (95C and 95D) with different metastatic potential was determined by real-time PCR and flow cytometry. 95C and 95D cells were transfected with the plasmid DNA containing CXCR4 coding gene or CXCR4 antisense nucleotide fragment, respectively, and the effects on in vitro cell migration, invasion, and adhesion and in vivo metastasis were measured. Results: Up-regulated expression of CXCR4 was detected in 34 tumors, which were further divided into 17 high expression cancers and 17 low expression cancers by their staining intensities. High CXCR4 tumors (13 of 17) were more prone to clinical metastasis in comparison with low expression tumors. CXCR4 was differentially expressed in 95C and 95D cells with low or high metastatic potential, and the surface expression of CXCR4 were 50% up-regulated or down-regulated following the stable transfection. The metastatic potential of NSCLC in vitro , such as migration, invasion, and adhesion, were significantly enhanced or impaired. In addition, neutralizing the interactions of stromal cell–derived factor-1/CXCR4 in vitro with CXCR4-specific antibodies inhibited the CXCR4-dependent migration, invasion, and adhesion. Furthermore, s.c. inoculation of lung cancer cells with low expression of CXCR4 in nude mice showed 0- to 2-fold decrease in lung metastatic foci than that with high expression of CXCR4. Conclusions: Differential expression of CXCR4 is associated with the metastatic potential of human NSCLC, raising the possibility that blockade of CXCR4/stromal cell–derived factor-1 interaction may lead the way to design novel therapeutic tools for the treatment of metastatic NSCLC patients.