Fig. 1

Elevated expression of CXCR2 is associated with poor prognosis of lung cancer patients. Immunohistochemical staining of CXCR2 was performed on the tumor pathological tissue microarrays of 93 patients with lung adenocarcinoma and 90 patients with lung squamous carcinoma. a, IHC analysis of CXCR2 expression in parenchyma and stroma of lung adenocarcinoma tissues and lung squamous cell carcinoma tissues. Scale bar, 50 μm. b-c, IHC scores of tumor cells and stroma cells of lung adenocarcinoma tissues (b) and lung squamous cell carcinoma tissues (c) (independently interpreted by two researchers, p = 0.046 and p < 0.001, respectively). The percentage of positive cells in tumor stroma was documented as 0 (none), 1 (< 10%), 2 (10–50%), 3 (51–80%) and 4 (> 80%). The intensity of positive cells was scored as 0 (no immunostaining), 1 (weak immunostaining), 2 (moderate immunostaining) and 3 (strong immunostaining). The immunostaining score and the percentage of immunoreactive cells were multiplied to get IRS ranging from 0 to 12. Data was shown as mean ± SEM. d-e, Tumor cells and stromal cells were divided into CXCR2 high-expression group and CXCR2 low-expression group according to the IHC score. The optimum cut-off values of IHC were 5.0 for adenocarcinoma and 5.5 for squamous cell carcinoma which were based on the Youden indexes from receiver operating characteristic (ROC) curves. The overall survival of lung adenocarcinoma (d) and lung squamous cell carcinoma patients (e) were compared by Kaplan-Meier survival curves and the log-rank test. IHC, immunohistochemical. *p < 0.05, **p < 0.01, ***p < 0.001, ns represents p>0.05