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XPD DNA nucleotide excision repair gene polymorphisms associated with DNA repair deficiency predict better treatment outcomes in secondary acute myeloid leukemia.

ABSTRACT: Pharmacogenetic studies in DNA repair pathway have consistently demonstrated correlations between the XRCC1 Arg399Gln, XPD Lys751Gln and XPD Asp312Gln genotypes, previously associated with suboptimal DNA repair, and differential cancer treatment outcomes. We evaluated these polymorphisms and XPD haplotypes in adult de novo (n=214) and secondary (n=79) acute myeloid leukemia (AML) patients treated with cytarabine and anthracycline chemotherapy. Genotyping was performed by MALDI-TOF mass spectrometry. Logistic and proportional hazards regression models were used to evaluate relationships. Differential responses were observed in secondary, but not de novo, AML. Among secondary AML patients, the odds of achieving complete remission (CR) were higher for the XPD 312Asn/Asn (OR= 11.23; 95% CI, 2.23-56.63) and XPD 751Gln/Gln (OR= 7.07; 95% CI, 1.42-35.18) genotypes. The XPD diplotypes were coded as the combination of two of the following haplotypes: haplotype A=(Lys)751A/(Asp) 312G; B=(Gln)751C/(Asn)312A; C=(Lys)751A/(Asn)312A; and D=(Gln)751C/(Asp)312G. The BB diplotype was associated with CR attainment [OR=18.31; 95% CI: 2.08-283.57] and longer survival [HR=0.31; 95% CI: 0.14-0.73] compared to the referent AA diplotype. The XPD 751 CC, 312GA, 312AA genotypes and the XPD DC diplotype were also associated with longer overall survival (OS).Thus, XPD codon 312 and 751 variant genotypes and haplotypes containing at least one variant allele may predict better treatment responses. If validated, these findings could support stratification of chemotherapy in secondary AML.

SUBMITTER: Kuptsova-Clarkson N

PROVIDER: S-EPMC3049908 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:The causative link between UV exposure and melanoma development is well known, however the mechanistic relationship remains incompletely characterised. UVA and UVB components of sunlight are implicated in melanomagenesis; however the majority of studies have focused on the effects of UVB and UVC light. Interestingly, melanoma tumour sequencing has revealed an overrepresentation of mutations signature of unrepaired UV-induced DNA damage. Repair of UVA-induced DNA damage is thought to occur primarily through the Nucleotide Excision Repair (NER) pathway, which recognises and repairs damage either coupled to transcription (Transcription Coupled Repair; TCR), or through global genome scanning (Global Genome Repair; GGR). Current literature suggests NER is deficient in melanoma, however the cause of this remains unknown; and whether reduced NER activity in response to UVA may be involved in melanoma development remains uncharacterised. In this study we aimed to determine if melanoma cells exhibit reduced levels of NER activity in response to UVA. METHODS:Melanocyte and melanoma cell lines were UVA-irradiated, and DNA damage levels assessed by immunodetection of Cyclobutane Pyrimidine Dimer (CPD) and (6-4) Photoproduct [(6-4)PP] lesions. Expression of NER pathway components and p53 following UVA treatment was quantified by qPCR and western blot. RESULTS:UVA did not induce detectable induction of (6-4)PP lesions, consistent with previous studies. Repair of CPDs induced by UVA was initiated at 4 h and complete within 48 h in normal melanocytes, whereas repair initiation was delayed to 24 h and >40 % of lesions remained in melanoma cell lines at 48 h. This was coupled with a delayed and reduced induction of GGR component XPC in melanoma cells, independent of p53. CONCLUSION:These findings support that NER activity is reduced in melanoma cells due to deficient GGR. Further investigation into the role of NER in UVA-induced melanomagenesis is warranted and may have implications for melanoma treatment.

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XPD DNA nucleotide excision repair gene polymorphisms associated with DNA repair deficiency predict better treatment outcomes in secondary acute myeloid leukemia.

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