CXCR4 promotes cisplatin-resistance of non-small cell lung cancer in a CYP1B1-dependent manner

Chemoresistance is the main cause of treatment failure and high mortality in advanced lung cancer. Cisplatin, an important chemotherapeutic agent for lung cancer, has been observed to show enormously reduced chemotherapeutic efficacy owing to the development of chemoresistance. CXCR4, a stromal-derived-factor-1 specific chemokine receptor, is highly expressed in non-small cell lung cancer (NSCLC) tissues and participates in cancer progression by regulating cell growth, apoptosis or invasion. In this study, we therefore investigated whether CXCR4 plays a role in the cisplatin associated resistance in NSCLC. We detected the expression of CXCR4 in tissue specimens from 64 NSCLC patients by immunohistochemistry. Cisplatin-resistant NSCLC cells A549/DDP and its parental A549 cells were employed in this study. RNA interference was performed to silence the CXCR4. The influence of CXCR4 on tumor cell chemoresistance, apoptosis and growth, as well as the relationship between CXCR4 and the expression of cytochrome p450 associated molecule CYP1B1 in NSCLC were evaluated. Finally, we found CXCR4 was significantly highly expressed in cisplatin-resistant NSCLC patients and the A549/DDP cell line. CXCR4 inhibition by siRNA reversed chemoresistance and decreased tumor cell proliferation. Bioinformatics analysis showed that the expression of CYP1B1 had a positive correlation with CXCR4, the CYP1B1 silencing significantly decreased CXCR4 expression levels and cisplatin resistance. Immunohistochemistry also verified that CYP1B1 was upregulated in NSCLC tissues of cisplatin-resistant patients. In conclusion, our results indicate that overexpression of CXCR4 in NSCLC promotes cisplatin resistance via CXCR4-mediated CYP1B1 upregulation. Thus, it can be used as a potential therapeutic target in NSCLC chemoresistance patients and be used as a clinical predictor of cisplatin response.