Interleukin 7/interleukin 7 receptor induce c-Fos/c-Jun-dependent vascular endothelial growth factor-D up-regulation: A mechanism of lymphangiogenesis in lung cancer

Interleukin 7 (IL-7) is known to promote lymphangiogenesis. To study the relationship between IL-7 and the lymphangiogenic factor, vascular endothelial growth factor (VEGF)-D, in human lung cancer cells and its impact on the prognosis of lung cancer patients, we investigated how IL-7 regulates VEGF-D. We found that, in lung cancer cell lines, IL-7/IL-7 receptor (IL-7R) increase the expression of VEGF-D and phosphorylation of c-Fos/c-Jun, induce c-Fos and c-Jun heterodimer formation, and enhance c-Fos/c-Jun DNA binding activity to regulate VEGF-D. In addition, the expression levels of IL-7 and IL-7R correlated well with that of VEGF-D, lymphatic vessels density (LVD), clinical stages, lymph node metastasis, and poor prognosis in 100 human non-small cell lung cancer (NSCLC) specimens analysed. Taken together, our results provide evidence that IL-7/IL-7R induce VEGF-D up-regulation and promote lymphangiogenesis via c-Fos/c-Jun pathway in lung cancer.