Environment-Sensitive Fluorescent Probe Enables Assessment of Anaplastic Lymphoma Kinase Activity in Nonsmall Cell Lung Cancer.

Anaplastic lymphoma kinase ( ALK ) rearrangements have been identified as key oncogenic drivers of a subset of nonsmall cell lung cancer (NSCLC). The final chimeric protein of the fusion gene can be constitutively activated, which accounts for the growth and proliferation of ALK-rearranged tumors and thus strongly associates with cancer invasion and metastasis. Diagnostic tools enabling the visualization of ALK activity in a structure-function-based approach are highly desirable to determine ALK status and guide ALK tyrosine kinase inhibitor (ALK-TKI) treatment making. Here, we describe the design, synthesis, and application of a new environment-sensitive fluorescent probe HX16 by introducing an environment-sensitive fluorophore 4-sulfonamidebenzoxadiazole to visualize ALK activity in living cancer cells and tumor tissue slices (mouse model and human biopsy sample). HX16 is a multifunctional chemical tool based on the pharmacophore of ALK-TKI (ceritinib) and can specifically target the kinase domain of ALK with a high sensitivity. Using flow cytometry and confocal microscopy, HX16 enables visualization of ALK activity in various cancer cells with distinct ALK fusion genes, as well as xenograft mouse models. Importantly, HX16 was also applied to visualize ALK activity in a tumor biopsy from a NSCLC patient with ALK- echinoderm microtubule-associated protein-like-4 fusion gene for prediction of ALK-TKI sensitivity. These results demonstrate that strategically designed ALK-TKI-based probe allows the assessment of ALK activity in tumor tissues and hold promise as a useful diagnostic tool in predicting ALK-TKI therapy response.