Loss of the xeroderma pigmentosum group B protein binding site impairs p210 BCR/ABL1 leukemogenic activity

DNA repair pathways as guardians of the genome: Therapeutic potential and possible prognostic role in hematologic neoplasms

DNA repair pathways, which are also identified as guardians of the genome, protect cells from frequent damage that can lead to DNA breaks. The most deleterious types of damage are double-strand breaks (DSBs), which are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). Single strand breaks (SSBs) can be corrected through base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Failure to restore DNA lesions or inappropriately repaired DNA damage culminates in genomic instability and changes in the regulation of cellular functions. Intriguingly, particular mutations and translocations are accompanied by special types of leukemia. Besides, expression patterns of certain repair genes are altered in different hematologic malignancies. Moreover, analysis of mutations in key mediators of DNA damage repair (DDR) pathways, as well as investigation of their expression and function, may provide us with emerging biomarkers of response/resistance to treatment. Therefore, defective DDR pathways can offer a rational starting point for developing DNA repair-targeted drugs. In this review, we address genetic alterations and gene/protein expression changes, as well as provide an overview of DNA repair pathways.

Association of MDR1 G2677T polymorphism and leukemia risk: evidence from a meta-analysis

In the light of the relationship between the MDR1 G2677T polymorphism and the risk of leukemia remains inclusive or controversial. For better understanding of the effect of MDR1 G2677T polymorphism on leukemia risk, we performed a meta-analysis. Eligible studies were identified through a search of electronic databases such as PubMed, Excerpta Medica Database (Embase), Cochrane Library, and Chinese Biomedical Literature Database (CBM). The association between the MDR1 G2677T polymorphism and leukemia risk was conducted by odds ratios (ORs) and 95% confidence intervals (95% CI). A total of seven publications including eight studies with 1,229 cases and 1,097 controls were included in the meta-analysis. There was no association between MDR1 G2677T polymorphism and leukemia risk in all of five models in overall populations (T vs. G: OR = 1.00, 95% CI = 0.88-1.12, P = 0.914; TT vs. GG: OR = 0.97, 95% CI = 0.75-1.26, P = 0.812; TG vs. GG: OR = 1.00, 95% CI = 0.92-1.08, P = 0.939; TT vs.

TG/GG

OR = 0.98, 95% CI = 0.67-1.43, P = 0.906; TT/TG vs. GG: OR = 1.00, 95% CI = 0.95-1.06, P = 0.994). However, the significant association was found in others (Table 2) under the homozygote model (TT vs. GG: OR = 0.68, 95% CI = 0.48-0.94, P = 0.020) and recessive model (TT vs.

TG/GG

OR = 0.63, 95% CI = 0.43-0.92, P = 0.016). In the subgroup analysis, according to the type of leukemia, significant association was found between MDR1 G2677T polymorphism and myeloid leukemia but not lymphoblastic leukemia (TT vs. GG: OR = 0.66, 95% CI = 0.46-0.95, P = 0.026; TT vs.

TG/GG

OR = 0.56, 95% CI = 0.38-0.84, P = 0.005). The results suggested that there was no association between MDR1 G2677T polymorphism and leukemia risk in overall populations, but significant association was found in others populations (Asians and Africans), and myeloid leukemia indicated that G2677T polymorphism might be a protective factor in the susceptibility of myeloid leukemia and in Asians and Africans.

Association of XRCC3 Thr241Met polymorphism and leukemia risk: evidence from a meta-analysis

The relationship between the X-ray repair cross-complementing group 3 (XRCC3) Thr241Met (rs861539) polymorphism and the risk of leukemia remains inclusive or controversial. For a better understanding of the effect of XRCC3 Thr241Met (rs861539) polymorphism on leukemia risk, we performed a meta-analysis. All eligible studies were identified through a search of PubMed, Excerpta Medica Database (Embase) and the Chinese Biomedical Literature Database (CBM) up to August 2013. The association between the XRCC3 Thr241Met (rs861539) polymorphism and leukemia risk was analyzed by means of odds ratios (ORs) and 95% confidence intervals (CI). Ultimately, seven studies with 1070 cases and 1850 controls were included in the meta-analysis. There was no association between Thr241Met polymorphism and leukemia risk in any of the five models in the overall populations (T vs. C: OR = 1.43, 95% CI = 0.95-2.13, p = 0.086; TT vs. CC: OR = 1.71, 95% CI = 0.88-3.33, p = 0.112; TC vs. CC: OR = 1.35, 95% CI = 0.96-1.91, p = 0.089; TT vs.

TC/CC

OR = 1.59, 95% CI = 0.87-2.89, p = 0.132; TT/TC vs. CC: OR = 1.37, 95% CI = 0.98-1.94, p = 0.070). In subgroup analysis according to ethnicity, a significant association was found between XRCC3 Thr241Met (rs861539) polymorphism and leukemia risk in Asian but not in Caucasian or mixed populations. In conclusion, the results suggest no association between XRCC3 Thr241Met (rs861539) polymorphism and leukemia risk in the overall populations but a significant association between XRCC3 Thr241Met (rs861539) polymorphism and leukemia risk in the Asian population. Considering the limited sample size and ethnicities included in the meta-analysis, further large-scale, well-designed studies are needed to confirm our results.