The expression of CXCR4, CXCL12 and CXCR7 in malignant pleural mesothelioma

The chemokine CXCL12 and its receptors, CXCR4 and CXCR7, are involved in tumour progression, metastasis, and survival. We investigated the expression of CXCR4, CXCL12, and CXCR7 in malignant pleural mesothelioma to determine if they are possible biomarkers and potential therapeutic targets. Forty-one mesothelioma tumour tissues, ten normal human pleural tissues, and two mesothelioma cell lines were stained with anti-CXCR4, anti-CXCL12, anti-CXCR7, and anti-p-Akt antibodies. RT-PCR was performed to determine the expression of CXCR4, CXCL12, and CXCR7 in six human mesothelioma cell lines (H28, 211H, H2052, ms-1, H290, and H513) and one human normal mesothelial cell line, LP9. These seven cell lines were also stained with anti-CXCR7. We found that CXCR4 and CXCL12 were expressed in 97.6% and 78.0% mesothelioma tissue samples, concurrently with strong expression of p-Akt (R(2) = 0.739 and 0.620, respectively). In addition, CXCR7 expression was weaker than CXCR4 expression in mesothelioma tissues. Furthermore, RT-PCR showed that CXCR4 and CXCL12 were overexpressed in 5/6 mesothelioma cell lines (211H, H2052, ms-1, H290, and H513), whereas CXCR7 was overexpressed in only 2/6 (H513 and H2052). Moreover, we found that the CXCR4 antagonist AMD3100 inhibited the growth of all five mesothelioma cell lines that overexpress CXCR4 and CXCL12. Our results suggest that the Akt-mTOR pathway is involved during the interruption of the CXCL12/CXCR4 axis in these five mesothelioma cell lines. In conclusion, CXCR4 and CXCL12 are highly expressed in most mesothelioma cell lines and tumour tissues, suggesting that CXCR4 and CXCL12 may be used as biomarkers for patients with mesothelioma. The CXCL12-CXCR4 interaction may be a potential therapeutic target for mesothelioma.