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Tumor-Extrinsic Axl Expression Shapes an Inflammatory Microenvironment Independent of Tumor Cell Promoting Axl Signaling in Hepatocellular Carcinoma
oleh: Kristina Breitenecker, Denise Heiden, Tobias Demmer, Gerhard Weber, Ana-Maria Primorac, Viola Hedrich, Gregor Ortmayr, Thomas Gruenberger, Patrick Starlinger, Dietmar Herndler-Brandstetter, Iros Barozzi, Wolfgang Mikulits
Format: | Article |
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Diterbitkan: | MDPI AG 2024-04-01 |
Deskripsi
The activation of the receptor tyrosine kinase Axl by Gas6 is a major driver of tumorigenesis. Despite recent insights, tumor cell-intrinsic and -extrinsic Axl functions are poorly understood in hepatocellular carcinoma (HCC). Thus, we analyzed the cell-specific aspects of Axl in liver cancer cells and in the tumor microenvironment. We show that tumor-intrinsic Axl expression decreased the survival of mice and elevated the number of pulmonary metastases in a model of resection-based tumor recurrence. Axl expression increased the invasion of hepatospheres by the activation of Akt signaling and a partial epithelial-to-mesenchymal transition (EMT). However, the liver tumor burden of Axl<sup>+/+</sup> mice induced by diethylnitrosamine plus carbon tetrachloride was reduced compared to systemic Axl<sup>−/−</sup> mice. Tumors of Axl<sup>+/+</sup> mice were highly infiltrated with cytotoxic cells, suggesting a key immune-modulatory role of Axl. Interestingly, hepatocyte-specific Axl deficiency did not alter T cell infiltration, indicating that these changes are independent of tumor cell-intrinsic Axl. In this context, we observed an upregulation of multiple chemokines in Axl<sup>+/+</sup> compared to Axl<sup>−/−</sup> tumors, correlating with HCC patient data. In line with this, Axl is associated with a cytotoxic immune signature in HCC patients. Together these data show that tumor-intrinsic Axl expression fosters progression, while tumor-extrinsic Axl expression shapes an inflammatory microenvironment.