Lyn regulates creatine uptake in an imatinib-resistant CML cell line

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Imatinib mesylate (imatinib) is a first-line treatment for chronic myeloid leukemia (CML).
• Imatinib-resistant CML cells (Myl-R) exhibit elevated Lyn kinase activity and intracellular creatine pools compared to sensitive cells (Myl).

Purpose of the Study:

• To investigate the origin of elevated creatine pools in imatinib-resistant CML cells.
• To elucidate the role of Lyn kinase in regulating creatine uptake and Na+/K+-ATPase activity.

Main Methods:

• Stable isotope metabolic labeling and creatine depletion experiments.
• Inhibition and shRNA knockdown of Lyn kinase and Na+/K+-ATPase pump.
• Western blot analysis to assess protein phosphorylation.

Main Results:

• Enhanced creatine accumulation in Myl-R cells is dependent on extracellular uptake, not de novo synthesis or SLC6A8 transporter.
• Lyn kinase activity correlates with Na+/K+-ATPase phosphorylation at Tyr10 (pY10).
• Lyn overexpression increases Na+/K+-ATPase pY10, while Lyn inhibition reduces it and decreases creatine uptake.
• Cyclocreatine, a creatine analog, significantly reduces Myl-R cell viability.

Conclusions:

• Lyn kinase regulates creatine uptake by phosphorylating and modulating Na+/K+-ATPase pump activity.
• Kinase regulation of the Na+/K+-ATPase is crucial for cellular creatine uptake and energy metabolism.