PKMYT1 EXPRESSION PREDICTS GENOMIC INSTABILITY AND POOR SURVIVAL IN CHRONIC LYMPHOCYTIC LEUKEMIA

Chronic lymphocytic leukemia (CLL) is a hematologic malignancy marked by genomic instability and substantial clinical heterogeneity. Although genetic and epigenetic alterations have been linked to disease progression, the precise molecular mechanisms driving these processes remain poorly understood. Given the critical role of cell cycle regulation and genome maintenance in cancer biology, kinases involved in these pathways are of particular interest. One such kinase, PKMYT1, is known to regulate cell cycle checkpoints and preserve genomic integrity. Notably, PKMYT1 overexpression has been associated with aggressive clinical behavior and poor prognosis in several solid tumors, including triple-negative breast and prostate cancers. Despite this, the role of PKMYT1 in CLL has not yet been systematically explored. This study aimed to investigate PKMYT1 expression in CLL patient samples and its association with cytogenetic abnormalities, clinical features, and overall survival. We further evaluated the functional relevance of PKMYT1 as a potential therapeutic target in CLL cells. PKMYT1 expression was quantified by RT-qPCR in peripheral blood samples from 55 CLL patients and 10 healthy donors. Cytogenetic abnormalities were assessed by G-banding. Public RNA-seq data from 1,148 CLL patients (via cBioPortal) were used for differential expression analysis, pathway enrichment (DAVID, GSEA), and survival modeling. Functional validation was performed in the MEC1 CLL cell line using the selective PKMYT1 inhibitor GSK-1520489A. Importantly, elevated PKMYT1 expression was significantly associated with high-risk cytogenetic features, including complex karyotypes, and increased leukocyte counts, highlighting its potential link to disease aggressiveness. Transcriptomic analysis revealed that PKMYT1-high cases were enriched for pathways involved in DNA repair, chromatin remodeling, and mitotic control—key processes underlying genomic instability and malignant progression. Interestingly, although PKMYT1 overexpression was linked to aggressive molecular features, low PKMYT1 expression was paradoxically associated with significantly shorter overall survival, suggesting a complex and possibly context-dependent role in CLL pathobiology. Furthermore, pharmacological inhibition of PKMYT1 in MEC1 cells led to a marked reduction in cell viability, reinforcing its functional importance in CLL cell survival and underscoring its potential as a therapeutic target. Our findings identify PKMYT1 as a novel biomarker of genomic instability and disease outcome in CLL. The dual prognostic implications and functional significance of PKMYT1 expression support its potential as a valuable therapeutic target, particularly in high-risk CLL subsets. Supported by the University of Brasília (UnB), Flow Diagnósticos, and CNPq.