JAK2/STAT3 signaling pathway activation mediates tumor angiogenesis by upregulation of VEGF and bFGF in non-small-cell lung cancer

We investigated the clinical significance of Janus Kinase 2/Signal Transducer and Activator of Transcription 3 (JAK2/STAT3), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) during angiogenesis in non-small-cell lung carcinoma. JAK2, phospho-JAK2 (pJAK2), STAT3, and phospho-STAT3 (pSATA3) were observed in 40/68 (58.8%), 39/68 (57.4%), 49/68 (72.1%) and 40/68 (58.8%) of the cases. The high expression levels of molecules involved in the JAK2/STAT3 signaling pathway were associated with a decreased survival rate. Of the total number of cases, 73.5% were positive for VEGF and 80.9% for bFGF. Microvessel density (MVD), as determined by CD34 staining and morphology, was higher in NSCLC samples with high pJAK2 and pSTAT3 expression, and the patients with high MVD had poor survival status. In addition, the expression of pSTAT3 correlated with VEGF (r = 0.593) and bFGF (r = 0.519) (p < 0.05). Inhibiting JAK2 and knocking down STAT3 both suppressed STAT3 activation and reduced the expression of VEGF and bFGF in A549 and NCI-H292 cells, demonstrating that STAT3 activation was associated with VEGF and bFGF expression in the two human lung carcinoma cell lines. Therefore, STAT3 may be a critical molecular target for powerful intervention in NSCLC anti-angiogenesis therapy.