Protumoral effect of macrophage through Axl activation on mucoepidermoid carcinoma

Pharmaceutical inhibition of AXL suppresses tumor growth and invasion of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common type of cancer in a number of regions of the world, including East Asia, South Africa and Iran. It is often associated with poor prognosis rates. Tyrosine-protein kinase receptor UFO (AXL) is overexpressed in a subset of ESCC tumors, therefore the present study aimed to determine the effect of R428, a selective inhibitor of AXL, on ESCC tumor cells. TE1 and KYSE150 cell lines were used as models to investigate the effects of R428 treatment. The proliferative rate of the tumor cells was analyzed using MTT and colony formation assays. In addition, cell migration and invasion rates were analyzed using wound healing and Matrigel assays, respectively. The expression levels of matrix metalloproteinase (MMP)2 and MMP9, and the activation of protein kinase B (AKT), extracellular signal-regulated kinase (ERK) and AXL signaling were analyzed using gelatin zymography and western blotting. The results revealed that R428 inhibited the proliferative and invasive abilities of both cell lines. Furthermore, AXL, AKT and ERK signaling were all decreased in response to R428 treatment, alongside the expression levels of MMP2 and MMP9. In conclusion, the results of the present study suggested that R428 treatment may suppress ESCC tumor cell proliferation and invasion, representing a potential therapeutic target for ESCC.

Does Axl have potential as a therapeutic target in pancreatic cancer?

INTRODUCTION

Pancreatic cancer is a leading cause of cancer-related death. Metastasis, therapy resistance, and immunosuppression are dominant characteristics of pancreatic tumors. Strategies that enhance the efficacy of standard of care and/or immune therapy are likely the most efficient route to improve overall survival in this disease. Areas covered: Axl, a member of the TAM (Tyro3, Axl, MerTK) family of receptor tyrosine kinases, is involved in cell plasticity, chemoresistance, immune suppression, and metastasis in various cancers, including pancreatic cancer. This review provides an overview of Axl and its function in normal conditions, summarizes the regulation and function of Axl in cancer, and highlights the contribution of Axl to pancreatic cancer as well as its potential as a therapeutic target. Expert opinion: Axl is an attractive therapeutic target in pancreatic cancer because it contributes to many of the roadblocks that hamper therapeutic efficacy. Clinical evidence supporting Axl inhibition in pancreatic cancer is currently limited; however, multiple clinical trials have been initiated or are in the planning phase to test the effect of inhibiting Axl in conjunction with standard therapy in pancreatic cancer patients. We anticipate that these studies will provide robust validation of Axl as a therapeutic target in pancreatic cancer.

IQGAP1 binds the Axl receptor kinase and inhibits its signaling

Axl is a tyrosine kinase receptor that is important for hematopoiesis, the innate immune response, platelet aggregation, engulfment of apoptotic cells and cell survival. Binding of growth arrest-specific protein 6 (Gas6) activates Axl signaling, but the mechanism of inactivation of the Axl receptor is poorly understood. In the present study, we show that IQGAP1 modulates Axl signaling. IQGAP1 is a scaffold protein that integrates cell signaling pathways by binding several growth factor receptors and intracellular signaling molecules. Our in vitro analysis revealed a direct interaction between the IQ domain of IQGAP1 and Axl. Analysis by both immunoprecipitation and proximity ligation assays demonstrated an association between Axl and IQGAP1 in cells and this interaction was decreased by Gas6. Unexpectedly, reducing IQGAP1 levels in cells significantly enhanced the ability of Gas6 to stimulate both Axl phosphorylation and activation of Akt. Moreover, IQGAP1 regulates the interaction of Axl with the epidermal growth factor receptor. Our data identify IQGAP1 as a previously undescribed suppressor of Axl and provide insight into regulation of Axl function.

Function of Axl receptor tyrosine kinase in non-small cell lung cancer

Axl receptor tyrosine kinase (hereafter Axl) is a member of the tyrosine-protein kinase receptor Tyro3, Axl and proto-oncogene tyrosine-protein kinase Mer family of receptor tyrosine kinases, possessing multiple different functions in normal cells. Axl is overexpressed and activated in numerous different human cancer types, triggering several signaling pathways and enhancing tumor progression. The present review assesses previous studies on the function of Axl in non-small cell lung cancer (NSCLC). Axl is overexpressed in the tumor tissues of a number of patients with NSCLC and is associated with poorer clinical outcomes; it promotes NSCLC tumor growth, invasion/metastasis, drug resistance and the epithelial-mesenchymal transition, thus providing a survival advantage to tumor cells. Therefore, Axl may be a promising target in NSCLC treatment.