FoxM1 Inhibition Sensitizes Resistant Glioblastoma Cells to Temozolomide by Downregulating the Expression of DNA-Repair Gene Rad51

Background: The therapeutically important DNA repair gene O6-methylguanine DNA methyltransferase (MGMT) is silenced by promoter methylation in human brain cancers. The co-players/regulators associated with this process and the subsequent progression of MGMT gene transcription beyond the non-coding exon 1 are unknown. As a follow-up to our recent finding of a predicted second promoter mapped proximal to the exon 2 [Int. J. Mol. Sci.2021, 22(5), 2492], we addressed its significance in MGMT transcription. Methods: RT-PCR, RT q-PCR, and nuclear run-on transcription assays were performed to compare and contrast the transcription rates of exon 1 and exon 2 of the MGMT gene in glioblastoma cells. Results: Bioinformatic characterization of the predicted MGMT exon 2 promoter showed several consensus TATA box and INR motifs and the absence of CpG islands in contrast to the established TATA-less, CpG-rich, and GAF-bindable exon 1 promoter. RT-PCR showed very weak MGMT-E1 expression in MGMT-proficient SF188 and T98G GBM cells, compared to active transcription of MGMT-E2. In the MGMT-deficient SNB-19 cells, the expression of both exons remained weak. The RT q-PCR revealed that MGMT-E2 and MGMT-E5 expression was about 80- to 175-fold higher than that of E1 in SF188 and T98G cells. Nuclear run-on transcription assays using bromo-uridine immunocapture followed by RT q-PCR confirmed the exceptionally lower and higher transcription rates for MGMT-E1 and MGMT-E2, respectively. Conclusions: The results provide the first evidence for transcriptional pausing at the promoter 1- and non-coding exon 1 junction of the human MGMT gene and its activation/elongation through the protein-coding exons 2 through 5, possibly mediated by a second promoter. The findings offer novel insight into the regulation of MGMT transcription in glioma and other cancer types.

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DNA Repair Gene Polymorphism and the Risk of Mitral Chordae Tendineae Rupture

Disease Markers ◽

10.1155/2015/825020 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6

Author(s):

Aysel Kalayci Yigin ◽

Mehmet Bulent Vatan ◽

Ramazan Akdemir ◽

Muhammed Necati Murat Aksoy ◽

Mehmet Akif Cakar ◽

...

Keyword(s):

Dna Repair ◽

Fragment Length Polymorphism ◽

Control Group ◽

Chordae Tendineae ◽

Repair Gene ◽

Repair Capacity ◽

Dna Repair Capacity ◽

Dna Repair Gene ◽

Increased Risk ◽

Polymerase Chain

Polymorphisms in Lys939Gln XPC gene may diminish DNA repair capacity, eventually increasing the risk of carcinogenesis. The aim of the present study was to evaluate the significance of polymorphism Lys939Gln in XPC gene in patients with mitral chordae tendinea rupture (MCTR). Twenty-one patients with MCTR and thirty-seven age and sex matched controls were enrolled in the study. Genotyping of XPC gene Lys939Gln polymorphism was carried out using polymerase chain reaction- (PCR-) restriction fragment length polymorphism (RFLP). The frequencies of the heterozygote genotype (Lys/Gln-AC) and homozygote genotype (Gln/Gln-CC) were significantly different in MCTR as compared to control group, respectively (52.4% versus 43.2%,p=0.049; 38.15% versus 16.2%,p=0.018). Homozygote variant (Gln/Gln) genotype was significantly associated with increased risk of MCTR (OR = 2.059; 95% CI: 1.097–3.863;p=0.018). Heterozygote variant (Lys/Gln) genotype was also highly significantly associated with increased risk of MCTR (OR = 1.489; 95% CI: 1.041–2.129;p=0.049). The variant allele C was found to be significantly associated with MCTR (OR = 1.481; 95% CI: 1.101–1.992;p=0.011). This study has demonstrated the association of XPC gene Lys939Gln polymorphism with MCTR, which is significantly associated with increased risk of MCTR.

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DNA Repair Gene Polymorphisms and Susceptibility to Urothelial Carcinoma in a Southeastern European Population

Current Oncology ◽

10.3390/curroncol28030174 ◽

2021 ◽

Vol 28 (3) ◽

pp. 1879-1885

Author(s):

Maria Samara ◽

Maria Papathanassiou ◽

Lampros Mitrakas ◽

George Koukoulis ◽

Panagiotis J. Vlachostergios ◽

...

Keyword(s):

Dna Repair ◽

Urothelial Carcinoma ◽

European Population ◽

Nucleotide Polymorphisms ◽

Environmental Carcinogens ◽

Repair Gene ◽

High Exposure ◽

Dna Repair Gene ◽

Increased Risk ◽

Xrcc3 Thr241met

Single nucleotide polymorphisms (SNPs) in DNA repair genes may predispose to urothelial carcinoma of the bladder (UCB). This study focused on three specific SNPs in a population with high exposure to environmental carcinogens including tobacco and alcohol. A case-control study design was used to assess for presence of XPC PAT +/−, XRCC3 Thr241Met, and ERCC2 Lys751Gln DNA repair gene SNPs in peripheral blood from patients with UCB and healthy individuals. One hundred patients and equal number of healthy subjects were enrolled. The XPC PAT +/+ genotype was associated with a 2-fold increased risk of UCB (OR = 2.16; 95%CI: 1.14–4; p = 0.01). The −/+ and +/+ XPC PAT genotypes were more frequently present in patients with multiple versus single tumors (p = 0.01). No association was detected between ERCC2 Lys751Gln genotypes/alleles, and risk for developing UCB. Presence of the XRCC3 TT genotype (OR = 0.14; 95%CI:0.07–0.25; p < 0.01) and of the T allele overall (OR = 0.26; 95%CI:0.16–0.41; p < 0.01) conferred a protective effect against developing UCB. The XPC PAT −/+ and XRCC3 Thr241Met SNPs are associated with predisposition to UCB. The XPC PAT −/+ SNP is also an indicator of bladder tumor multiplicity, which might require a more individualized surveillance and treatment.

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Patients with Systemic Sclerosis Present Increased DNA Damage Differentially Associated with DNA Repair Gene Polymorphisms

The Journal of Rheumatology ◽

10.3899/jrheum.130376 ◽

2014 ◽

Vol 41 (3) ◽

pp. 458-465 ◽

Cited By ~ 11

Author(s):

Gustavo Martelli Palomino ◽

Carmen L. Bassi ◽

Isabela J. Wastowski ◽

Danilo J. Xavier ◽

Yara M. Lucisano-Valim ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Systemic Sclerosis ◽

Blood Cells ◽

Gene Polymorphisms ◽

Peripheral Blood Cells ◽

Dna Repair Genes ◽

Repair Gene ◽

Dna Repair Gene ◽

Repair Genes

Objective.Patients with systemic sclerosis (SSc) exhibit increased toxicity when exposed to genotoxic agents. In our study, we evaluated DNA damage and polymorphic sites in 2 DNA repair genes (XRCC1Arg399Gln andXRCC4Ile401Thr) in patients with SSc.Methods.A total of 177 patients were studied for DNA repair gene polymorphisms. Fifty-six of them were also evaluated for DNA damage in peripheral blood cells using the comet assay.Results.Compared to controls, the patients as a whole or stratified into major clinical variants (limited or diffuse skin involvement), irrespective of the underlying treatment schedule, exhibited increased DNA damage.XRCC1(rs: 25487) andXRCC4(rs: 28360135) allele and genotype frequencies observed in patients with SSc were not significantly different from those observed in controls; however, theXRCC1Arg399Gln allele was associated with increased DNA damage only in healthy controls and theXRCC4Ile401Thr allele was associated with increased DNA damage in both patients and controls. Further, theXRCC1Arg399Gln allele was associated with the presence of antinuclear antibody and anticentromere antibody. No association was observed between these DNA repair gene polymorphic sites and clinical features of patients with SSc.Conclusion.These results corroborate the presence of genomic instability in SSc peripheral blood cells, as evaluated by increased DNA damage, and show that polymorphic sites of theXRCC1andXRCC4DNA repair genes may differentially influence DNA damage and the development of autoantibodies.

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