Expression of axl in lung adenocarcinoma and correlation with tumor progression. Neoplasia 7:1058–1064

We used the Transwell system to select highly invasive cell lines from minimally invasive parent cells, and we compared gene expression in paired cell lines with high and low invasive potentials. Axl was relatively over-expressed in the highly invasive cell lines when compared with their minimally invasive counterparts. However, there is only limited information about the role of Axl in cancer invasion. The biologic function of Axl in tumor invasion was investigated by over-expression of full-length Axl in minimally invasive cells and by siRNA knockdown of Axl expression in highly invasive cells. Overexpression of Axl in minimally inva-sive cells increased their invasiveness. siRNA reduced cell invasiveness as Axl was downregulated in highly invasive cells. We further investigated the protein ex-pression of Axl by immunohistochemistry and its cor-relation with clinicopathologic features. Data from a study of 58 patient specimens showed thatAxl immuno-reactivity was statistically significant with respect to lymph node status (P <.0001) and the patient’s clinical stage (P <.0001). Our results demonstrate that Axl protein kinase seems to play an important role in the invasion and progression of lung cancer