OBJECTIVETo explore the role of CXCR4/SDF-1alpha axis in organ-specific metastasis of nasopharyngeal carcinoma (NPC) by assessment of CXCR4 expression in NPC cells and SDF-1alpha expression in distant target organs of NPC.

METHODSThirty patients with NPC and fifteen normal subjects were recruited in this study. The expressions of CXCR4 in NPC and normal cases were identified by RT-PCR and immunohistochemistry (IHC), then the relationship between CXCR4 expression and clinicopathological factors was analyzed. IHC was also used to analyze the SDF-1alpha protein expression in normal cervical lymph nodes (including normal superior and inferior deep cervical lymph nodes), bone marrow, lung, liver, kidney and colon tissues of NPC patients (5 cases/each group).

RESULTSThe relative expression level of CXCR4 mRNA in NPC (0.71 +/- 0.22) was significantly higher than that of normal nasopharynx tissues (0.14 +/- 0.07, F = 27.94, P < 0.05). The relative expression level of CXCR4 protein in NPC (1.58 +/- 0.59) was significantly higher than that of normal nasopharynx tissues (0.51 +/- 0.22, F = 17.75, P < 0.05). The high expression levels of CXCR4 mRNA and protein in NPC were closely related to clinical stage, cervical lymph node metastasis and cancer cell differentiation (P < 0.05). SDF-1alpha protein was strongly expressed in normal superior deep cervical lymph nodes, bone marrow, lung and liver (2.35 +/- 0.67), but absent or very poor expression in inferior deep cervical lymph nodes, kidney and colon tissues (0.68 +/- 0.23), and the differences between them were statistically significant (t = 10.13, P < 0.01).

CONCLUSIONCXCR4 is closely correlated to metastasis of nasopharyngeal carcinoma. CXCR4/SDF-1alpha axis may play an important role in organ-specific metastasis of NPC.