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Inhibition of Src, SIRT1 or HDAC6 Reduces Transendothelial Migration of Acute Lymphoblastic Leukemia B cells
Author(s) -
Camacho Karina Elizabeth Jimenez,
Martinez Ramon Castellanos,
Schnoor Michael
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.02452
Subject(s) - cortactin , lamellipodium , invadopodia , microbiology and biotechnology , proto oncogene tyrosine protein kinase src , cell migration , podosome , biology , cancer research , phosphorylation , cell , cancer cell , cytoskeleton , cancer , biochemistry , genetics
B‐cell acute lymphoblastic leukemia (B‐ALL) is the most common leukemia in children. B‐ALL cells have the ability to extravasate and infiltrate bone marrow and organs such as lungs, testis and central nervous system. Dynamic actin cytoskeletal remodeling is needed to accomplish transendothelial migration. Cortactin is an actin‐binding protein which accumulates in lamellipodia and invadopodia and regulates neutrophil transendothelial migration during inflammation. Cortactin is overexpressed in B‐cells of B‐ALL patients, and significantly correlates with bone marrow colonization, organ infiltration, drug resistance and disease relapse. Cortactin is a target of Src kinase, and the deacetylases SIRT1 and HDAC6 and as such is prone for post‐translational modifications that regulate its function and localization. Phosphorylation of cortactin at residue Y421 supports lamellipodia and invadopodia formation, whereas acetylation of cortactin diminishes its affinity for F‐actin and decreases cell migration. However, it remains to be explored whether these modifications are required for the migratory advantage that cortactin overexpression bestows on B‐ALL cells. Thus, in this project, we investigate: first, whether pharmacological inhibition of Src, HDAC6 and SIRT1 in leukemic B‐cells reduce transendothelial migration and bone marrow colonization; and second, whether these effects depend on cortactin overexpression. We found that cortactin is constitutively phosphorylated at Y421 in the pre‐B ALL cell line REH and that this phosphorylation is increased after CXCL12 stimulation over time. Of note, Src kinase inhibition with PP2 in leukemic B cells reduced phospho‐cortactin levels and impaired leukemic cell transmigration across HUVEC monolayers and BM organoid colonization. These data suggest that src‐mediated cortactin phosphorylation is required to trigger transmigration. This idea will be further corroborated using cortactin‐depleted REH cells. Moreover, SIRT1 inhibition with EX‐527 and HDAC6 inhibition with Tubastatin‐A also significantly reduced transendothelial migration and bone marrow organoid colonization suggesting that cortactin activation is also regulated by its acetylation status. Taken together, these findings highlight the importance of post‐translational modifications for the regulation of migratory processes of leukemic B cells. Future analysis of the underlying exact molecular mechanisms will contribute to a better understanding of B‐ALL disease progression.