Differential expression of Axl and correlation with invasion and multidrug resistance in cancer cells.

Dysregulation of Axl receptor tyrosine kinases is implicated in the pathogenesis of several sensitive and refractory cancers. In this study we showed that Axl expression was upregulated in drug-resistant cancer cells, as compared to those in parental cells. Downregulation of Axl expression by RNAi led to a decrease of K562/ADR and MCF-7/ADR cells invasion, proliferation in soft agar, and increased cells chemosensitivity in vitro. In nude mice bearing xenografts, downregulation of Axl in MDR cells enhanced the anticancer activity of intraperitoneally applied chemotherapeutic drugs. Our observations suggest that Axl represents a promising gene for overcoming MDR in cancer therapy.