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

ABSTRACT: BACKGROUND:Imatinib mesylate (imatinib) is the first-line treatment for newly diagnosed chronic myeloid leukemia (CML) due to its remarkable hematologic and cytogenetic responses. We previously demonstrated that the imatinib-resistant CML cells (Myl-R) contained elevated Lyn activity and intracellular creatine pools compared to imatinib-sensitive Myl cells. METHODS:Stable isotope metabolic labeling, media creatine depletion, and Na+/K+-ATPase inhibitor experiments were performed to investigate the origin of creatine pools in Myl-R cells. Inhibition and shRNA knockdown were performed to investigate the specific role of Lyn in regulating the Na+/K+-ATPase and creatine uptake. RESULTS:Inhibition of the Na+/K+-ATPase pump (ouabain, digitoxin), depletion of extracellular creatine or inhibition of Lyn kinase (ponatinib, dasatinib), demonstrated that enhanced creatine accumulation in Myl-R cells was dependent on uptake from the growth media. Creatine uptake was independent of the Na+/creatine symporter (SLC6A8) expression or de novo synthesis. Western blot analyses showed that phosphorylation of the Na+/K+-ATPase on Tyr 10 (Y10), a known regulatory phosphorylation site, correlated with Lyn activity. Overexpression of Lyn in HEK293 cells increased Y10 phosphorylation (pY10) of the Na+/K+-ATPase, whereas Lyn inhibition or shRNA knockdown reduced Na+/K+-ATPase pY10 and decreased creatine accumulation in Myl-R cells. Consistent with enhanced uptake in Myl-R cells, cyclocreatine (Ccr), a cytotoxic creatine analog, caused significant loss of viability in Myl-R compared to Myl cells. CONCLUSIONS:These data suggest that Lyn can affect creatine uptake through Lyn-dependent phosphorylation and regulation of the Na+/K+-ATPase pump activity. GENERAL SIGNIFICANCE:These studies identify kinase regulation of the Na+/K+-ATPase as pivotal in regulating creatine uptake and energy metabolism in cells.

SUBMITTER: Okumu DO 

PROVIDER: S-EPMC7055176 | biostudies-literature |

REPOSITORIES: biostudies-literature