Role of TAM Family Kinases in t(6;9)-positive Acute Myeloid Leukemia

Abstract

Leukemia refers to the cancer of white blood cells in which aberrant proliferation of immature blasts is seen due to the differentiation blockage. Acute myeloid leukemia (AML), the most common acute leukemia, is characterized by rapid growth of immature white blood cells in the bone marrow due to genetic mutations like t(6;9) leading to DEK/CAN fusion proteins. This high-risk subtype has a poor prognosis, with limited treatments beyond standard chemotherapy. TAM kinases, including AXL, TYRO3, and MER, promote cancer cell growth and drug resistance in various cancer types. The current study aimed to look the expression of TAM family kinases and explore their role in DEK/CAN-positive high-risk AML along with their pharmacological targeting with TAM kinases inhibitors. FKH-1, an AML cell line was used to investigate the expression of TAM Kinases and also treated with varying concentrations of these inhibitors R428 for AXL-RTK, LDC1267 for TYRO3-RTK, and UNC2250 for MERTK to observe their effects on cell proliferation. MTT assays were utilized to quantify cell viability and determine the optimal inhibitory dosages. The study investigated the combinatorial effect of these inhibitors with the standard line of treatment, Imatinib. Moreover, the expression of c-Myc and Eya3, as well as tumor suppressor genes (p16, p21 and p53) were examined via qPCR. Lastly, DNA fragmentation assay was performed to identify either inhibition of proliferation was related to induction of apoptosis or not. TAM family kinases are highly expressed in FKH-1 cell line (p<0.0001), the only available DEK/CAN positive AML model and pharmacological targeting of TAM family kinases reduce the proliferation of FKH-1 cell line in dose dependent manner (p<0.0001). Further, co-targeting of ETV6/ABL1 Abstract 2 with imitinib and TAM family kinases AXL-RTK with R428, MerTK with UNC2250 and TYRO3 with LDC1267 showed additive antiproliferative effect(p<0.001). The inhibition of proliferation was not related to induction of apoptosis but related to down regulation of c-Myc, Eya3 (p<0.0001) and the up regulation of cell cycle inhibitors including p16, p53and p21 (p<0.0001). Our results provide clear evidence of the involvement of TAM family kinases in the leukemogenic potential of the DEK/CANpositive AML and suggest TAM family kinases as potential candidate targets for therapeutic intervention in future