Anaplastic lymphoma kinase enhances Wnt signaling through R-spondin: A new dimension to ALK-mediated oncogenesis

Anaplastic lymphoma kinase receptor (ALK) is a receptor tyrosine kinase that plays a key role in the progression of several cancers and is activated by ligands such as ALKAL1 and ALKAL2. To identify additional molecules that interact with ALK, we constructed comprehensive genetic and molecular level networks. Notably, our study identified R-spondins, growth factors known to enhance Wnt signaling, as novel interacting partners of ALK. Protein-protein docking studies revealed that R-spondins bind to the TNF-like and EGF-like domains of ALK, which are critical for the interaction of ALK with its known ligand ALKAL2. These docking outcomes were further validated by molecular dynamics simulations, and approximate binding affinity calculations that confirmed the stability and conformational behavior of the ALK and R-spondin complex. These in silico findings indicate a strong interaction between ALK and R-spondins. To investigate whether this interaction influences Wnt signaling in vitro, we conducted a Wnt signaling reporter assay (TOP Flash/FOP Flash) in neuroblastoma cells by introducing Rspo2, Wnt3a, and crizotinib, an ALK inhibitor. The results showed a decrease in the TOP/FOP ratio when ALK was inhibited. Collectively, our study reveals a novel role for ALK in enhancing Wnt signaling via R-spondins, providing new dimension into ALK-mediated oncogenesis.