DNA Repair Expression Profiling to Identify High-Risk Cytogenetically Normal Acute Myeloid Leukemia and Define New Therapeutic Targets

RAD51 and RAD50 genetic polymorphisms from homologous recombination repair pathway are associated with disease outcomes and organ toxicities in AML

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous malignancy that responds to various therapies. The sensitivity of leukemia cells to chemotherapy is affected by the DNA damage response (DDR). In this study, we examined the association between RAD51 rs1801320, XRCC3 rs861539, NBS1 rs1805794, MRE11 rs569143, and RAD50 rs2299014 variants of the homologous recombination repair (HRR) pathway and AML outcomes.

MATERIAL AND METHODS

PCR-RFLP was applied for the genotyping of 67 newly diagnosed cases. We performed Sanger sequencing to confirm the results of RFLP genotyping. Outcomes and organ toxicities were collected and χ2 testing was performed for association analysis.

RESULTS

RAD50 variant allele carriers were protected from renal and hepatic toxicities (p = 0.024 and p = 0.045, respectively), and were associated with resistant disease (p = 0.001). RAD51 variant alleles were protected from liver toxicity (p = 0.031) and correlated with disease resistance (p = 0.012).

CONCLUSION

RAD50 rs2299014 and RAD51 rs1801320 polymorphisms may be useful for drug adjustment in AML.

APEX1 Polymorphisms Affect Acute Myeloid Leukemia Risk, and Its Expression Is Involved in Cell Proliferation and Differentiation

INTRODUCTION

The link between DNA repair gene polymorphisms and cancer susceptibility has gained significant attention. Thus, we investigated the impact of base excision repair (BER) gene polymorphisms on acute myeloid leukemia (AML) risk and pathogenesis.

METHODS

In total, 106 patients with AML and 191 healthy controls were included in the study, wherein polymorphisms in four BER genes (APEX1, MUTYH, OGG1, and XRCC1) were examined.

RESULTS

Notably, the APEX1-656 T>G polymorphism exhibited a significant association with AML risk in the recessive (TT vs. TG + GG) (p = 0.046) and co-dominant models (TT vs. GG) (p = 0.02). Assessing APEX1 expression levels, APEX1 expression was elevated in the bone marrow of patients with AML compared with that in controls (p = 0.02). Subsequently, we compared the percentages of CD34+ cells between the APEX1 high or low expression groups, revealing a significant difference (high vs. low = 29.9% vs. 11.5%, p = 0.01). Additionally, we observed reduced APEX1 expression in HL60 cells differentiated with all-trans retinoic acid (p < 0.001). We hypothesized that APEX1 expression could correlate with stemness and analyzed its expression in stem and differentiated cells.

CONCLUSIONS

In the GSE48558 dataset, AML cells and normal CD34+ cells expressed APEX1 at higher levels than did granulocytes (p < 0.01). Functional experiments revealed that APEX1 knockdown led to a reduction in AML cell proliferation. These findings indicated that APEX1 polymorphisms were a potential risk factor for AML and highlighted the important role of APEX1 in regulating AML cell differentiation and proliferation.

DNA damage accumulation and repair defects in FLT3-ITD acute myeloid leukemia: Implications for clonal evolution and disease progression

Acute myeloid leukemia is a group of hematological diseases that have a high mortality rate. During the development of this pathology, hematopoietic cells acquire chromosomal rearrangements and multiple genetic mutations, including FLT3-ITD. FLT3-ITD is a marker associated with a poor clinical prognosis and involves the activation of pathways such as PI3K/AKT, MAPK/ERK, and JAK/STAT that favor the survival and proliferation of leukemic cells. In addition, FLT3-ITD leads to overproduction of reactive oxygen species and defective DNA damage repair, both implicated in the appearance of new mutations and leukemic clones. Thus, the purpose of this review is to illustrate the molecular mechanisms through which FLT3-ITD generates genetic instability and how it facilitates clonal evolution with the generation of more resistant and aggressive cells. Likewise, this article discusses the feasibility of combined therapies with FLT3 inhibitors and inhibitors of DNA repair pathways.

High Expression of DC-STAMP Gene Predicts Adverse Outcomes in AML

Acute myeloid leukemia (AML) is a genetically heterogeneous hematological malignancy with poor prognosis. We explored the RNA sequence data and clinical information of AML patients from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database to search for the core molecule for prognosis. The DC-STAMP expression was significantly higher in AML patients, which was linked to old age, unfavorable cytogenetic risk, and death (all p < 0.05). Furthermore, it was revealed that high DC-STAMP expression was an independent unfavorable factor for overall survival (OS) by univariate analysis [hazard ratio (HR): 2.683; 95% confidence interval (CI): 1.723–4.178; p < 0.001] and multivariate analysis (HR: 1.733; 95% CI: 1.079–2.781; p = 0.023). The concordance index (C-index 0.734, 95% CI: 0.706–0.762), calibration curves, and decision curve analysis showed the certain predictive accuracy of a nomogram model based on multivariate analysis for OS. In addition, we found that the differentially expressed gene (DEG) enrichment pathways of high- and low-DC-STAMP expression group enrichment pathways were focused on channel activity and platelet alpha granule by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), while gene set enrichment analysis (GSEA) pathways were mainly involved in mTORC1 signaling and TNF-α signaling via the NF-kB pathway. Moreover, a protein–protein interaction (PPI) network demonstrated that DC-STAMP interacted with two hub genes (PPBP and PF4), which were highly regulated and associated with poor survival. Finally, high DC-STAMP expression showed a significantly positive correlation with four immune cell [NK CD56 (dim) cells, macrophages, cytotoxic cells, and CD8 (+) T cells] infiltration and high level of immune checkpoint genes (PDCD1, CD274, CTLA-4, and TIGIT). Therefore, our results suggest that high expression of DC-STAMP predicts adverse outcomes for AML patients.