PRL-3 facilitates angiogenesis and metastasis by increasing ERK phosphorylation and up-regulating the levels and activities of Rho-A/C in lung cancer

Aims: The aim of this study was to investigate the mechanism of PRL-3 in inducing angiogenesis and lymphangiogenesis to promote distant and lymph node metastasis in human lung cancer tissues and cells. Methods: We investigated the expression of PRL-3, VEGF, and VEGF-C from 94 patients with non-small cell lung cancer (NSCLC) using immunohistochemical staining. The relationship between PRL-3 expression and microvessel density (MVD), lymphatic vessel density (LVD), clinicopathological factors, and surgical treatment outcome was also studied. Following this, we studied the effect on A549 by blocking PRL-3. Results: PRL-3 expression in NSCLC was high, and this over-expression is correlated with advanced clinical stage (p=0.019), distant metastasis (p=0.001), lymph node metastasis (p=0.001), and poor post-operative survival. PRL-3 over-expression was associated with vascular endothelial growth factor (VEGF; p=0.000) and VEGF-C (p=0.008) expressions, MVD and LVD (p=0.000 and p=0.000). Blocking PRL-3 expression in A549 cell resulted in decreased cellular proliferative, migratory, and invasive abilities, and VEGF, VEGF-C, pERK, Rho-A, and Rho-C expression was inhibited. Following inhibition of either Rho or pERK, VEGF expression was down-regulated. Conclusions:PRL-3 induces microvascular and lymphatic vessel formation by facilitating VEGF and VEGF-C expression in lung cancer tissues, thus promoting distant and lymph node metastasis of lung cancer. PRL-3 up-regulates pERK and Rho expression and activity, facilitating VEGF expression, and accelerating angiogenesis and distant metastasis. How to regulate VEGF-C expression needs to be further studied.