TOPKi-NBD: a fluorescent small molecule for tumor imaging

Area of Science:

• Biochemistry
• Molecular Imaging
• Oncology

Background:

• Lymphokine-activated killer T cell-originated protein kinase (TOPK) is a potential molecular target in various cancers.
• Developing targeted imaging agents can significantly improve cancer diagnosis and treatment planning.

Purpose of the Study:

• To develop and validate a fluorescently labeled inhibitor of TOPK (lymphokine-activated killer T cell-originated protein kinase) for potential use in tumor imaging.
• To assess the specificity, tumor uptake, and detectability of the fluorescent TOPK inhibitor in vitro, in vivo, and ex vivo models.

Main Methods:

• Conjugation of the TOPK inhibitor OTS514 with a fluorescent molecule (NBD) to create TOPKi-NBD.
• In vitro, in vivo (using HCT116 colorectal cancer xenografts in NSG mice), and ex vivo imaging studies.
• Confocal microscopy, IVIS Spectrum imaging, and binding affinity assays (EC50) were employed.

Main Results:

• TOPKi-NBD was synthesized with high yield (67%) and purity (97%).
• The fluorescent inhibitor exhibited comparable target affinity to the parent compound OTS514.
• Specific tumor uptake and intracellular detection of TOPKi-NBD were observed in vivo and ex vivo, confirmed by blocking studies.

Conclusions:

• The development of TOPKi-NBD represents a significant advancement in creating TOPK-specific fluorescent imaging agents.
• TOPK is a viable molecular target for developing novel cancer-specific imaging agents with broad in vitro and in vivo applications.