Análise da expressão de genes envolvidos na síntese de translesão e na integridade do DNA em pacientes com leucemia mieloide crônica em uso de inibidores de tirosina-quinase

Abstract

Introduction: Chronic Myeloid Leukemia (CML) is a hematologic neoplasm characterized by the presence of the Philadelphia chromosome (Ph), resulting from the t(9;22)(q34;q11) translocation, which generates the BCR-ABL fusion gene. This gene encodes an oncoprotein with constitutive tyrosine kinase activity that drives CML pathogenesis by promoting DNA damage and compromising genomic integrity. Tyrosine kinase inhibitors (TKIs), such as imatinib, dasatinib, and nilotinib, are fundamental in the treatment of CML; however, concerns remain regarding their genotoxic effects and the role of DNA damage repair and damage tolerance mechanisms under therapeutic pressure. Objective: This study aimed to investigate the expression of genes involved in translesion synthesis and maintenance of genomic integrity (REV1, SETD2, APEX1, and POLB) in patients with CML receiving first- or second-generation TKIs, and to explore their implications for genomic stability and treatment response. Methods: A cross-sectional study was conducted involving 71 patients with chronic-phase CML and 25 healthy individuals as the control group. Clinical and laboratory data were collected from medical records. Peripheral blood samples were obtained, and gene expression was quantified by RT-qPCR. Differences in gene expression between groups and prognostic variables were evaluated using Mann-Whitney and Kruskal-Wallis tests with Dunn/Bonferroni post hoc analysis. Multivariate logistic regression (stepwise method) and ROC curve analyses were employed to assess the predictive value of genes for the absence of complete cytogenetic response (CCyR) and molecular response (MR). Additionally, a MANOVA was performed, adjusted for therapeutic response (CCyR, MR) and type of TKI, to identify joint effects on gene expression. Results: In the initial comparison, a significant reduction in POLB and APEX1 expression was observed in CML patients compared to controls (p < 0.0001), indicating impairment of the base excision repair (BER) pathway. Patients with an altered karyotype showed higher expression of APEX1 (p < 0.0001), and those classified as low-risk according to the EUTOS score exhibited higher POLB levels (p = 0.049). Stratification by type of TKI demonstrated that dasatinib or nilotinib use was associated with increased expression of REV1 and SETD2 (p < 0.005) compared to imatinib. MANOVA indicated a statistically significant effect on REV1 (p = 0.001) and SETD2 (p = 0.045) expression, reflecting the influence of treatment type and clinical response. In ROC curve analyses, REV1 showed an AUC of 0.733 for absence of CCyR (95% CI: 0.564–0.909) and 0.721 for absence of MR (95% CI: 0.564–0.877). In multivariate logistic regression, REV1 overexpression increased the odds of absence of CCyR by approximately 16-fold (OR = 15.9; p = 0.039), while high SETD2 expression exerted a protective effect (OR = 0.358; p = 0.022). Additionally, low APEX1 expression was more pronounced in patients refractory to achieving CCyR, underscoring the essential role of BER in maintaining genomic stability. Conclusion: The results indicate that deficiency of POLB and APEX1, combined with activation of REV1 and SETD2, is strongly associated with genomic instability and therapeutic resistance in CML. The use of second-generation TKIs further reinforced the reliance on damage tolerance mechanisms, highlighting the importance of the REV1-mediated TLS pathway. REV1 overexpression emerged as an independent predictor of poor prognosis, whereas SETD2 exerted a protective effect, suggesting their potential as molecular biomarkers for risk stratification and optimization of therapeutic strategies. In this context, an integrated understanding of DNA repair and damage tolerance pathways provides critical insights for preventing clonal evolution and improving the clinical management of CML patients.