Elevated Platelets Enhance Cancer Cell Migration, Promote Hematogenous Metastasis and Associate with a Poor Prognosis in Advanced Non-small Cell Lung Cancer Cases

Although correlations between platelets and lung cancer has been recognized, effects on non-small cell lungcancer (NSCLC) metastasis remain to be determined in detail. In the present study, wound healing assays revealeda role of platelets in NSCLC cell migration . Thus the mean migration rate of lung adenocarcinoma A549 cellswas significantly elevated after co-culture with platelets (81.7±0.45% vs 41.0±3.50%, P<0.01). Expression ofGAPDH was examined by reverse transcription-polymerase chain reaction to study the effect of platelets onNSCLC cell proliferation. The result showed that the proliferation of A549 and SPC-A1 cells was not affected.Mouse models were established by transfusing A549 cells and SPC-A1 cells into mice lateral tail veins. Wefound tumor metastasis nodules in lungs to be increased significantly after co-transfusion with platelets (inA549, 4.33±0.33 vs 0.33±0.33, P=0.01; in SPC-A1, 2.67±0.33 vs 0.00±0.00, P=0.01). In addition, consecutiveinoperable patients with newly diagnosed NSCLC (TNM stage III or IV) between January 2009 and December2011 were retrospectively reviewed. Using the Kaplan-Meier method, NSCLC patients with a high platelet countsdemonstrated a significantly shorter progression free survival compared with those with a low platelet count(>200×109/L, 3 months versus ≤200×109/L, 5 months, P=0.001). An elevated platelet count was also identified asan independent prognostic factor by Cox regression analysis for prgression free survival (adjusted hazard ratio:1.69; 95% CI: 1.16, 2.46; P=0.006). This study suggested that platelets might contribute to the hematogenousmetastatic process by promoting cancer cell migration, which eventually affects the prognosis of NSCLC.