Structural Basis of Inhibition of DCLK1 by Ruxolitinib

Area of Science:

• Oncology
• Biochemistry
• Structural Biology

Background:

• Doublecortin-like kinase 1 (DCLK1) plays a key role in gastrointestinal cancer progression, including tumor growth, invasion, metastasis, and stemness.
• Existing ATP-competitive inhibitors for DCLK1 have limitations in scaffold diversity and understanding binding specificities.
• There is a need for novel DCLK1 inhibitors and structural data to guide drug discovery.

Purpose of the Study:

• To repurpose the Janus kinase 1 (JAK1) inhibitor ruxolitinib as a DCLK1 inhibitor.
• To characterize the binding affinity and inhibitory activity of ruxolitinib against DCLK1.
• To determine the crystal structure of DCLK1 complexed with ruxolitinib to understand its interaction mode.

Main Methods:

• Biochemical assays to measure binding affinity and inhibitory activity of ruxolitinib against DCLK1.
• X-ray crystallography to obtain the structure of the DCLK1-ruxolitinib complex.
• Structural analysis to elucidate the binding mode and interactions.

Main Results:

• Ruxolitinib demonstrated micromolar binding affinity and inhibitory activity against DCLK1.
• The crystal structure of DCLK1 in complex with ruxolitinib was successfully determined.
• Structural analysis provided insights into the interaction of ruxolitinib with DCLK1.

Conclusions:

• Ruxolitinib can function as a nonspecific DCLK1 inhibitor.
• The characterized ruxolitinib-DCLK1 interaction serves as a foundation for structure-guided design of selective DCLK1 inhibitors.
• This repurposing strategy offers a starting point for developing novel therapeutics for gastrointestinal cancers targeting DCLK1.