Bemcentinib and Gilteritinib Inhibit Cell Growth and Impair the Endo-Lysosomal and Autophagy Systems in an AXL-Independent Manner

Abstract

AXL, a receptor tyrosine kinase from the TAM (TYRO3 AXL and MER) subfamily, and its ligand growth arrest-specific 6 (GAS6) are implicated in pathogenesis of a wide array of cancers, acquisition of resistance to diverse anticancer therapies and cellular entry of viruses. The continuous development of AXL inhibitors for treatment of patients with cancer and COVID-19 underscores the need to better characterize the cellular effects of AXL targeting. In the present study, we compared the cellular phenotypes of CRISPR–Cas9-induced depletion of AXL and its pharmacological inhibition with bemcentinib, LDC1267 and gilteritinib. Specifically, we evaluated GAS6–AXL signaling, cell viability and invasion, the endo-lysosomal system and autophagy in glioblastoma cells. We showed that depletion of AXL but not of TYRO3 inhibited GAS6-induced phosphorylation of downstream signaling effectors, AKT and ERK1/2, indicating that AXL is a primary receptor for GAS6. AXL was also specifically required for GAS6-dependent increase in cell viability but was dispensable for viability of cells grown without exogenous addition of GAS6. Furthermore, we revealed that LDC1267 is the most potent and specific inhibitor of AXL activation among the tested compounds. Finally, we found that, in contrast to AXL depletion and its inhibition with LDC1267, cell treatment with bemcentinib and gilteritinib impaired the endo-lysosomal and autophagy systems in an AXL-independent manner. Implications: Altogether, our findings are of high clinical importance as we discovered that two clinically advanced AXL inhibitors, bemcentinib and gilteritinib, may display AXL-independent cellular effects and toxicity.

AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma

“…Another study reported that AXL kinase inhibition by small molecule inhibitor bemcentinib inhibited the autophagic flux and induced immunogenic cell death in drugresistant non-small cell lung cancer in vitro (15). However, a prior study revealed that cell treatment with bemcentinib suppressed autophagy in an AXL-independent mechanism in glioblastoma cells (16). Although these studies clearly demonstrate that AXL positively regulates autophagy, the underlying molecular mechanism remains poorly understood in cancer cells.…”

Endocytic trafficking of GAS6–AXL complexes is associated with sustained AKT activation

“…Since LN229 cells express two TAMs, AXL and TYRO3 [ 31 , 58 ], and GAS6 was proposed to function as a ligand for all three TAMs [ 5 – 7 ], we first assessed the involvement of AXL and TYRO3 in internalization of GAS6. To discriminate which of these receptors is required for GAS6 endocytosis, we measured its accumulation in the previously generated AXL and TYRO3 knockout (KO) LN229 cells [ 31 ].…”

Comprehensive analysis of the novel omicron receptor AXL in cancers

“…AXL could bind to GAS6 and activate multiple pathways and participate in multiple processes of tumorigenesis, including regulating tumor cell growth, proliferation, migration, invasion and enhancement angiogenesis, etc [24] . Studies also showed that AXL was associated with resistance in patients to antitumor chemotherapy drugs (such as paclitaxel and cisplatin) or molecularly targeted drugs (such as erlotinib and gefitinib) [25] , [26] , [27] . AXL was also widely concerned as a drug target and the inhibitors against AXL mainly include small molecule inhibitors and monoclonal antibody drugs [28] .…”