SYNERGISTIC EFFECTS OF PIP4K2 INHIBITOR AND VENETOCLAX ON APOPTOSIS INDUCTION IN LEUKEMIA CELLS

Abstract

Venetoclax, a selective inhibitor of BCL2, has been introduced in clinical practice for the treatment of patients with acute myeloid leukemia (AML). PIP4K2s comprise a family of lipid kinases responsible to produce phosphoinositides (PtdIns4,5P2) with structural and signal transduction functions. The combined expression of PIP4K2A and PIP4K2C has been identified as an independent prognostic factor in AML. Recently, a selective pharmacological inhibitor of PIP4K2s was developed (THZ-P1-2). The present study aimed to characterize the antineoplastic potential of THZ-P1-2 in combination with venetoclax in a cellular model of AML. OCI-AML3 leukemia cell line that is resistant to venetoclax was used. Cell viability was evaluated by MTT assay and apoptosis by annexin V/PI and flow cytometry. OCI-AML3 were treated with graded doses of THZ-P1-2 (0, 1.6, 3.2, 6.4, 12.5, and 25 μM) and/or venetoclax (0, 3.2, 6.4, 12.5, 25, and 50 μM) for 48 hours. The data obtained from at least three independent experiments were analyzed by linear regression for the determination of IC50, and statistical analysis was performed by ANOVA and Bonferroni post-test using GraphPad Prism software. A p-value < 0.05 was considered significant. The combination of THZ-P1-2 and venetoclax synergistically reduced the viability of OCI-AML3 cells. The IC50 values for venetoclax, venetoclax plus 6.4 μM THZ-P1-2, and venetoclax plus 12.5 μM THZ-P1-2 were 7.3, 4.4, and 1.2 μM, respectively. Apoptosis assays corroborate these findings, the levels of apoptotic OCI-AML3 cells treated with vehicle, 6.4 μM venetoclax, 6.4 μM THZ-P1-P2, 12.5 μM THZ-P1-P2, 6.4 μM venetoclax plus 6.4 μM THZ-P1-2, and 6.4 μM venetoclax plus 12.5 μM THZ-P1- 2 were 3.8 ± 0.7%, 33.3 ± 4.8%, 18.5 ± 2.8%, 64.3 ± 4.3%, 78.3 ± 1.2% and 97.4 ± 0.3%, respectively (all p < 0.05). The pharmacological inhibition of PIP4K2 potentiates venetoclax-induced apoptosis in acute myeloid leukemia cells. These findings represent new opportunities for overcoming venetoclax resistance and improving therapeutic interventions in AML. Supported by FAPESP, CNPq, and CAPES.