Kinases and Phosphatases

Acute myeloid leukemia (AML) is one of the most aggressive types of leukemia, represented by the clonal proliferation of hematopoietic precursors, which mainly promotes quantitative and differentiation alterations, as well as normal hematopoiesis suppression. Throughout leukemogenesis, modifications may occur in several elements that make up cellular signaling pathways; among these, AURKA, AURKB, and PLK1 are key related regulators of mitotic progression and cellular proliferation. This study investigated the hematological profile and the expression of the AURKA, AURKB, and PLK1 genes in a cohort of individuals with AML, in order to understand their roles in the pathophysiology of the disease. The analyses revealed a significant hypoexpression of AURKA in the bone marrow of AML individuals compared to the control group (p = 0.0254) and AURKB showed no significant difference in bone marrow and peripheral blood samples. It was also observed a hyperexpression of PLK1 in bone marrow (p < 0.0001) and in peripheral blood (p = 0.0144). Our results also point to PLK1 as a potential biomarker for AML, since its hyperexpression did not differ with respect to gender, risk stratification, or age of the individuals. Finally, survival analyses indicate that AURKA expression in the bone marrow is associated with a protective factor and increased survival, and that those with higher expression of the three target genes had a lower mortality rate (p = 0.043).

Eukaryotic phosphorylation of serine and threonine residues is a central regulatory mechanism in cell signalling, carried out by more than 500 kinases and a diverse array of phosphatases. Traditionally understood as a two-component system driven by writers (kinases) and erasers (phosphatases), this regulatory network is now appreciated to involve additional proteins that modulate or interpret phosphorylation-dependent changes. Among them, the 14-3-3 protein family has emerged as a prominent example due to its ability to bind phosphorylated serine/threonine motifs—typically located within intrinsically disordered regions—and influence the activity, stability, or localization of its partners. In this review, we discuss the importance, evolution, structure, and dynamics of 14-3-3 proteins, as well as their interactions with small molecules—both natural and designed—that bind to them. We highlight several underexplored aspects of their molecular behaviour, integrate recent discoveries, and emphasize how these insights contribute to a broader understanding of phosphorylation-dependent regulation across eukaryotes.

Polo-like kinase 1 (PLK1) is a serine/threonine kinase that orchestrates multiple critical events during mitosis, including centrosome maturation, spindle assembly, kinetochore–microtubule attachment, and cytokinesis. Dysregulation and overexpression of PLK1 are frequently observed in various cancers, correlating with increased proliferation, metastatic potential, and poor prognosis, which highlights its potential as a therapeutic target. Traditional small-molecule inhibitors have predominantly focused on the ATP-binding site of the N-terminal kinase domain, effectively inducing mitotic arrest and apoptosis in tumor cells; however, these compounds often suffer from limited selectivity and off-target toxicity. The C-terminal Polo-box domain (PBD), responsible for substrate recognition and subcellular localization, has emerged as an alternative and highly selective target for inhibitor design, enabling the disruption of protein–protein interactions critical for PLK1 function. Here, we present a comprehensive review demonstrating the potential inhibition of several compounds against PLK1. This work establishes a foundation for future preclinical development of small molecule-based therapeutics against PLK1-dependent malignancies.