Class III Receptor Tyrosine Kinases in Acute Leukemia – Biological Functions and Modern Laboratory Analysis

Abstract

Acute myeloid leukemia (AML) is a complex disease caused by deregulation of multiple signaling pathways. Mutations in class III receptor tyrosine kinases (RTKs) have been implicated in alteration of cell signals concerning the growth and differentiation of leukemic cells. Point mutations, insertions, or deletions of RTKs as well as chromosomal translocations induce constitutive activation of the receptor, leading to uncontrolled proliferation of undifferentiated myeloid blasts. Aberrations can occur in all domains of RTKs causing either the ligand-independent activation or mimicking the activated conformation. The World Health Organization recommended including RTK mutations in the AML classification since their detection in routine laboratory diagnostics is a major factor for prognostic stratification of patients. Polymerase chain reaction (PCR)–based methods are well-validated for the detection of fms-related tyrosine kinase 3 (FLT3) mutations and can easily be applied for other RTKs. However, when methodological limitations are reached, accessory techniques can be applied. For a higher resolution and more quantitative approach compared to agarose gel electrophoresis, PCR fragments can be separated by capillary electrophoresis. Furthermore, high-resolution melting and denaturing high-pressure liquid chromatography are reliable presequencing screening methods that reduce the sample amount for Sanger sequencing. Because traditional DNA sequencing is time-consuming, next-generation sequencing (NGS) is an innovative modern possibility to analyze a high amount of samples simultaneously in a short period of time. At present, standardized procedures for NGS are not established, but when this barrier is resolved, it will provide a new platform for rapid and reliable laboratory diagnostic of RTK mutations in patients with AML. In this article, the biological and physiological role of RTK mutations in AML as well as possible laboratory methods for their detection will be reviewed.

Theoretical Studies Aimed at Finding FLT3 Inhibitors and a Promising Compound and Molecular Pattern with Dual Aurora B/FLT3 Activity

“…It is derived from the Piecewise Linear Potential (PLP), a simplified potential whose parameters are fit with protein-ligand structures and binding data scoring functions [15] and further extended in the GEMDOCK program (Generic Evolutionary Method for molecular DOCK) with a new hydrogen bond term and new charge schemes. The docking scoring function, E score , is defined by the following energy terms: E score = E inter + E intra (1) where the ligand-protein interaction energy, E inter , is given by…”

“…Feline McDonough Sarcoma (FMS)-like tyrosine kinase 3 (FLT3, EC: 2.7.10.1) is a class III receptor protein tyrosine kinase, wherein five immunoglobulin-like domains are present in the extracellular region [1]. Under normal conditions, this enzyme is expressed in the membranes of precursor hematopoietic cells and is important for cellular differentiation, proliferation, and multiplication.…”

“…Justamembranar domain mutations lead to a FLT3/ITD (internal tandem duplication) mutant allele, which has been associated with a decrease in leukemia remission of patients undergoing chemotherapy with a low response to standard cytotoxic agents [4]. Evidence shows that mutations in a justamembranar region interfere with the self-inhibitory mechanism, leading to a conformational modification and constitutive activation of this enzyme [1]. Bavetsias and Moore [5,6] showed that dual Aurora/FLT3 inhibitors might be more effective than selective FLT3 inhibitors in cases of AML mutations.…”

“…In the search for more efficient chemotherapic agents, FLT3/ITD inhibitors [7], such as Sunitinib (IC 50 = 34.0 nM), Quizartinib (IC 50 = 1.1 nM) [8], Midostaurin (IC 50 = 9.3 nM), Lestaurtinib (IC 50 = 8.6 nM), and Sorafenib (IC 50 = 18.5 nM) [9] (Figure 1) have been discovered, and although presenting tolerability and toxicity problems, this has also inspired new studies in the search for new promising anticancer agents. mutations in a justamembranar region interfere with the self-inhibitory mechanism, leading to a conformational modification and constitutive activation of this enzyme [1]. Bavetsias and Moore [5,6] showed that dual Aurora/FLT3 inhibitors might be more effective than selective FLT3 inhibitors in cases of AML mutations.…”

Current trends in targeted therapy of leukaemia and lymphoma

“…Small molecule medicines in the treatment of hematopoietic malignancies include tyrosine kinase inhibitors, histone deacetylase inhibitors, hypermethylation inhibitors, and proteasome inhibitors. The main targets for tyrosine kinase inhibitors (TKI) are PI3K/AKT, MAPK/ERK, JAK-STAT, STAT5, FLT3 and BTK which have been reported to be aberrantly activated in various acute and chronic leukaemias and lymphomas, typically initiating and maintaining cell proliferation [15,16] . The well-known representative of TKIs is the BCR-ABL fusion protein inhibitor used in the treatment of chronic myelogenous leukaemia (CML).…”