BACKGROUND

Tumor-associated immune factors are heterogeneous and play an important role in determining outcome in cancer patients. In this study, the expression levels of immune factors in tumor tissue-conditioned media from lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) were analyzed.

METHODS

LUAD and LUSC tissue specimens were collected immediately after surgery for antibody array analysis and real-time quantitative PCR.

RESULTS

Higher levels of chemokines MCP1/CCL2 (21.11-fold increase) and MIP-1β/CCL4 (19.33-fold increase) were identified in LUAD than in LUSC. Western blot and quantitative real-time PCR analyses showed higher co-expression of CCL2 and CCL4 in LUAD tissues compared to LUSC (P < 0.0001). Immunofluorescent co-staining showed a high percentage of CCL2 /CD68 and CCL4 /CD68 tumor-associated macrophages in LUAD compared to LUSC tissues, which might be responsible for the higher expression of CCL2 and CCL4 in LUAD samples. Kaplan-Meier curves showed that CCL2 overexpression in patients with LUSC was associated with beneficial overall survival (OS; P = 0.048) and progression-free survival (PFS; P = 0.012); however, LUAD patients with higher CCL2 expression had unfavorable OS (P = 6.7e-08) and PFS (P = 0.00098). Similarly, CCL4 overexpression predicted favorable PFS (P = 0.021) in patients with LUSC, but patients with high CCL4 levels in LUAD had shorter OS (P = 0.013).

CONCLUSION

Our study revealed that CCL2 and CCL4 expression levels could serve as potential prognostic biomarkers and therapeutic targets for NSCLC patients.