ALBERT

Description: Introduction: Src family non-receptor tyrosine kinase regulates diverse cellular responses mainly by activating PI3K signaling, an important pathway that contributes to many cancers pathology. HCK, a Src family member, is restricted expressed in hematopoietic cells; however, high levels of HCK have been reported in solid tumors and hematologic neoplasms and have been associated with a worse prognosis. Identification of unbalanced pathways and upregulated proteins and a better knowledge of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) pathogenesis could help identify potential druggable targets and new prognostic biomarkers. The clinical and biological role of HCK in MDS and AML pathophysiology has not yet been elucidated and may be a novel therapeutic approach. Aims : To evaluate HCK expression in hematopoietic stem cells (HSC/CD34+) and in total bone marrow (BM) cells from healthy donors and MDS and AML patients. We further attempted to analyze the HCK knockdown and drug inhibition on differentiation, proliferation, apoptosis and migration in HSC/CD34+ and in a panel of human leukemia cell lines (KG1a, U937, HL60, P39). Materials and Methods : A total of 34 healthy donors and 139 patients at diagnosis (MDS=75 [low-risk=46, high-risk=29], AML with Myelodysplastic related changes (AML-MRC)=21 and de novo AML=43), were included in the study. HCK gene and protein expression was analyzed by qPCR and Western blot. Results are expressed as median (minimum–maximum) after appropriate statistical analysis. For functional analysis, HCK was inhibited with specific lentiviral vector system in HSC/CD34+ (isolated from umbilical cord blood units and BM), KG1a, U937, HL60 and P39 cells. Apoptosis was evaluated by Annexin-V/PI, cell growth by CellTiter assay, migration by Transwell, CXCR4 expression and actin polymerization by flow cytometry. We also verified the effects of a HCK specific inhibitor, ASN05260065, kindly provided by ASINEX and Dr Maurizzio Bottas. Results : HCK mRNA were significantly increased in HSC/CD34+ from patients with MDS (4.87 [0.03-14.75]; P=.003) and AML (8.36 [0.70-24.47]; P=.003) compared to healthy donors (1.19 [0.06-3.02]). When patients were stratified according to WHO classification, HCK expression was significantly higher in low-risk MDS compared to high-risk and AML-MRC (8.10 [2.30–14.75] vs 3.22 [0.03–6.33] and 1.02 [0.70–2.78], P