High BMI1 mRNA expression in peripheral whole blood is associated with favorable prognosis in advanced non-small cell lung cancer patients.

Polycomb group member protein BMI1 is involved in maintaining cell identity, proliferation, differentiation and human oncogenesis. In the present study, we determined BMI1 mRNA expression in whole blood and evaluated the impact of the expression level on the treatment response and survival of 96 advanced NSCLC patients treated with first-line platinum-based chemotherapy. We also determined BMI1 mRNA expression in primary tumors from 22 operable NSCLC patients treated with radical surgery. We found that compared with control subjects, BMI1 mRNA expression in whole blood of advanced NSCLC patients was decreased (P<0.001). Similarly, we observed decreased BMI1 mRNA expression in primary tumors compared to normal lungs from operable NSCLC patients (P=0.001). We found high BMI1 mRNA expression in blood was associated with longer progression-free survival (PFS) (P=0.049) and overall survival (OS) (P=0.012) in advanced NSCLC patients treated with first-line platinum-based chemotherapy. However, no association between the BMI1 mRNA level and response to chemotherapy was found (P=0.21). Multivariate Cox proportional hazards regression analysis showed elevated BMI1 mRNA level in whole blood was an independent prognostic factor for longer PFS (P=0.012) and OS (P<0.001). In conclusion, BMI1 mRNA expression in whole blood might represent a new biomarker for the diagnosis and prognosis of NSCLC.