• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10457-10462
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• 2015

Homologous recombination repair (HRR) plays an important role in protection against carcinogenic factors. Genes regulating the HRR mechanisms may impair their functions and consequently result in increased cancer susceptibility. RAD 51 and XRCC3 are key regulators of the HRR pathway and genetic variability in these may contribute to the appearance and progression of various cancers including head and neck cancer (HNC). The aim of the present study was to compare the distribution of genotypes of RAD51 (135G/C, 172 G/T) and XRCC3 (Thr241Met) polymorphisms between HNC patients and controls. Each polymorphism was genotyped using the polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP) technique in 200 pathologically confirmed HNC patients along with 150 blood samples from normal, disease free healthy individuals. We observed that homozygous variant CC genotype of RAD51 135G/C was associated with a 2.5 fold increased HNC risk (OR=2.5; 95%CI=0.69-9.53; p<0.02), while second polymorphism of RAD 51 172 G/T, heterozygous variant GT genotype was associated with a 1.68 fold (OR=1.68; 95%CI=1.08-2.61; p<0.02) elevation when compared with controls. In the case of the Thr241Met polymorphism of XRCC3, we observed a 16 fold (OR=16; 95% CI=3.78-69.67; p<0.0002) increased HNC risk in patients compared to controls. These results further suggested that RAD51 (135G/C, 172 G/T) and XRCC3 (Thr241Met) polymorphisms may be effective biomarkers for genetic susceptibility to HNC. Larger studies are needed to confirm our findings and identify the underlying mechanisms.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.763-767
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• 2014

Aim: To study the contribution of genetic variation in RAD51 to risk of esophageal squamous cell carcinoma (ESCC). Methods: Three single nucleotide polymorphisms (SNPs) in RAD51 (rs1801320, rs4144242 and rs4417527) were genotyped in 316 ESCC patients and 316 healthy controls in Anyang area of China using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Demographic variables between cases and controls were statistically compared by T test and Chi-square test. Hardy-Weinberg equilibrium was evaluated by the Chi-square test. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure any association with ESCC. Haplotype frequencies were estimated by Phase 2.1. Result: The genotype frequencies of rs1801320, rs4144242 and rs4417527 in patients with ESCC demonstrated no significant differences from those in control group (P>0.05). When the haplotypes of these three SNPs were constructed and their relationships with ESCC risk investigated, however, CGG was observed to increase the risk (P=0.020, OR=2.289). Conclusions: There was no association between the three SNPs of RAD51 and ESCC susceptibility in our Chinese population. However, the CGG haplotype might be a risk factor.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.405-411
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• 2017

Homologous recombination occurs between homologous chromosomes and is significantly involved in programmed double-strand break (DSB) repair. Activation of two recombinases, Rad51 and Dmc1, is essential for an interhomolog bias during meiosis. Rad51 participates in both mitotic and meiotic recombination, and its strand exchange activity is regulated by an inhibitory factor during meiosis. Thus, activities of Rad51 and Dmc1 are coordinated to promote homolog bias. It has been reported that Hed1, a meiosis-specific protein in budding yeast, regulates Rad51-dependent recombination activity. Here, we investigated the role of Hed1 in meiotic recombination by ectopic expression of the protein after pre-meiotic replication in Saccharomyces cerevisiae. DNA physical analysis revealed that the overexpression of Hed1 delays the DSB-to-joint molecule (JM) transition and promotes interhomolog JM formation. The study indicates a possible role of Hed1 in controlling the strand exchange activity of Rad51 and, eventually, meiotic crossover formation.

• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10225-10229
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• 2015

Genetic polymorphisms in homologous recombination repair genes cause an abnormal development of cancerous cells. In the present study we evaluated the possibility of breast cancer association with single nucleotide polymorphisms of RAD51, XRCC2 and XRCC3 genes. Polymorphisms selected in this study were RAD51 135G/C, XRCC2 Arg188His; and XRCC3 Thr241Met. Each polymorphism was genotyped using Polymerase chain reaction-restriction fragment length polymorphism in study cohort of 306 females (156 breast cancer patients and 150 controls). We observed that heterozygous variant genotype (GC) of RAD51 135 G/C polymorphism was associated with a significantly (OR=2.70; 95%CI (0.63-1.79); p<0.03) increased risk of breast cancer. In case of the XRCC3 gene we observed that frequency of heterozygous (OR=2.88; 95%CI (1.02-8.14); p<0.02) and homozygous (OR=1.46; 95%CI (0.89-2.40); p<0.04) genotype of Thr241Met polymorphism were significantly higher in breast cancer patients. For the Arg188His polymorphism of XRCC2, ~2fold increase in breast cancer risk (OR=1.6, 95%CI = 0.73-3.50) was associated with GA genotype with a p value for trend of 0.03. Our results suggest that the 135G/C polymorphism of the RAD51, Thr241Met polymorphism of XRCC3 and Arg188His polymorphism of XRCC2 can be independent markers of breast cancer risk in Pakistan.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6727-6731
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• 2013

Homologous recombination (HR) repair has a crucial role to play in the prevention of chromosomal instability, and it is clear that defects in some HR repair genes are associated with many cancers. To evaluate the potential effect of some HR repair gene polymorphisms with differentiated thyroid carcinoma (DTC), we assessed Rad51 (135G>C), Rad52 (2259C>T), XRCC2 (R188H) and XRCC3 (T241M) polymorphisms in Iranian DTC patients and cancer-free controls. In addition, haplotype analysis and gene combination assessment were carried out. Genotyping of Rad51 (135G>C), Rad52 (2259C>T) and XRCC3 (T241M) polymorphisms was determined by PCR-RFLP and PCR-HRM analysis was carried out to evaluate XRCC2 (R188H). Separately, Rad51, Rad52 and XRCC2 polymorphisms were not shown to be more significant in patients when compared to controls in crude, sex-adjusted and age-adjusted form. However, results indicated a significant difference in XRCC3 genotypes for patients when compared to controls (p value: 0.035). The GCTG haplotype demonstrated a significant difference (p value: 0.047). When compared to the wild type, the combined variant form of Rad52/XRCC2/XRCC3 revealed an elevated risk of DTC (p value: 0.007). It is recommended that Rad52 2259C>T, XRCC2 R188H and XRCC3 T241M polymorphisms should be simultaneously considered as contributing to a polygenic risk of differentiated thyroid carcinoma.

• Journal of Plant Biotechnology
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• 제45권1호
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• pp.1-8
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• 2018

Meiosis is a specialized cell division, essential in most reproducing organisms to halve the number of chromosomes, thereby enabling the restoration of ploidy levels during fertilization. A key step in meiosis is homologous recombination, which promotes homologous pairing and generates crossovers (COs) to connect homologous chromosomes until their separation at anaphase I. These CO sites, seen cytologically as chiasmata, represent a reciprocal exchange of genetic information between two homologous non-sister chromatids. RAD51, the eukaryotic homolog of the bacterial RecA recombinase, plays a central role in homologous recombination (HR) in yeast and animals. Loss of RAD51 function causes lethality in the flowering plant, Arabidopsis thaliana, suggesting that RAD51 has a meiotic stage-specific function that is different from homologous pairing activity.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1505-1510
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• 2012

To aim of this was to observe emodin-mediated cytotoxicity and its influence on Rad51 and ERCC1 expressionin non-small cell lung cancer (NSCLC). NSCLC cells were cultured in vitro with emodin at various concentrations (0, 25, 50, 75 and $100\;{\mu}mol/L$) for 48h and the proliferation inhibition rate was determined by the MTT method. Then, NSCLC were treated with emodin (SK-MES-1 $40\;{\mu}mol/L$, A549 $70\;{\mu}mol/L$) or $20\;{\mu}mol/L$ U0126 (an ERK inhibitor) for 48 h, or with various concentrations of emodin for 48 h and the protein and mRNA expressions of ERCC1 and Rad51 were determined by RT-PCR and Western blot assay, respectively. Emodin exerted a suppressive effect on the proliferation of NSCLC in a concentration dependent manner. Protein and mRNA expression of ERCC1 and Rad51 was also significantly decreased with the dose. Vacuolar degeneration was observed in A549 and SK-MES-1 cell lines after emodin treatment by transmission electron microscopy. Emodin may thus inhibited cell proliferation in NSCLC cells by downregulation ERCC1 and Rad51.

• International Journal of Oncology
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• 제54권2호
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• pp.744-752
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• 2019

Fewer than 20% of patients diagnosed with pancreatic cancer can be treated with surgical resection. The effects of proton beam irradiation were evaluated on the cell viabilities in Panc-1 and Capan-1 pancreatic cancer cells. The cells were irradiated with proton beams at the center of Bragg peaks with a 6-cm width using a proton accelerator. Cell proliferation was assessed with the MTT assay, gene expression was analyzed with semi-quantitative or quantitative reverse transcription-polymerase chain reaction analyses and protein expression was evaluated by western blotting. The results demonstrated that Capan-1 cells had lower cell viability than Panc-1 cells at 72 h after proton beam irradiation. Furthermore, the cleaved poly (ADP-ribose) polymerase protein level was increased by irradiation in Capan-1 cells, but not in Panc-1 cells. Additionally, it was determined that histone H2AX phosphorylation in the two cell lines was increased by irradiation. Although a 16 Gy proton beam was only slightly up-regulated cyclin-dependent kinase inhibitor 1 (p21) protein expression in Capan-1 cells, p21 expression levels in Capan-1 and Panc-1 cells were significantly increased at 72 h after irradiation. Furthermore, it was observed that the expression of DNA repair protein RAD51 homolog 1 (RAD51), a homogenous repair enzyme, was decreased in what appeared to be a dose-dependent manner by irradiation in Capan-1 cells. Contrastingly, the transcription of survivin in Panc-1 was significantly enhanced. The results suggest that RAD51 and survivin are potent markers that determine the therapeutic efficacy of proton beam therapy in patients with pancreatic cancer.

• 미생물학회지
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• 제43권4호
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• pp.243-249
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• 2007

Centromere는 채세포분열과 생식세포분열 등 맡은 주요 기능을 담당하는 고도로 분화된 구조이다. Alphoid DNA (${\alpha}$-satellite)는 인간뿐 아니라 모든 영장류의 염색체 내 centromere에서 발견되는 반복서열의 대부분을 차지한다. 인간 인공염색체(Human Artificial Chromosome, HAC)의 개발에서 가장 핵심적인 부분은 centromere의 분리 및 안정적인 유지에 있다. 이 영역은 출아효모에서 alphoid DNA 반복서열을 hook으로 이용하여 Transformation-associated recombination (TAR) cloning법을 사용하여 선택적으로 분리할 수 있다. 이러한 실험방법으로 먼저 repeat array를 rolling-circle amplication (RCA)를 통하여 약 5 kb까지 길이를 연장시킨 후, 효모내에서 상동성재 조합을 이용한 TAR cloning법을 사용하여 분리할 수 있다. 이렇게 분리된 35 kb-50 kb 길이의 4종류의 centromeric DNA repeat arrays (2,4,5,6 mer)를 사용하여, 반복서열의 안정성 유지를 조사하기 위해 상동성재조 합 변이주인 rad51, rad52, rad54를 사용하여 비교 분석하였다. 야생주, rad51과 rad54 변이주를 이용하여 형질전환을 수행한 결과, 반복서열의 크기에 있어서 많은 변화를 나타내었다. 반면, rad52 변이주는 야생주와 다르게 형질전환빈도가 매우 낮은 비율로 나타났으나, centromeric DNA repeat array의 안정성은 3배 이상으로 높게 나타냈다. 이러한 결과들을 미루어, rad52 변이주를 사용하여 centromeric DNA repeat arrays의 형질전환실험에서 발생하는 맡은 변이를 줄일 수 있을 것으로 보인다. 이러한 유전적 방법은 HAC 제작에서 반복서열의 유지에 훨씬 효율적으로 사용할 수 있을 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제12권5호
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• pp.303-310
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• 2012

방사선 치료에 있어서 정확한 환자 포지셔닝과 셋업은 치료의 성패를 좌우할 수 있는 중요한 인자이다. 기존의 방사선 치료실내에 장착된 3-laser system을 이용한 셋업에서, 최근에는 체표면 윤곽 스캐닝 시스템(C-Rad system)의 사용이 시도되고 있다. 체표면 윤곽 스캐닝 시스템의 유용성을 평가하기 위하여 C-Rad system과 3-laser system을 이용한 셋업 오차의 정확도를 비교, 평가함으로써 임상에서의 유용성을 확인하고자 하였다. 인체부위는 내부적인 움직임이 없고, 고정용구의 적용이 간편한 두경부로 한정하였으며, Alderson Rando anthropomorphic phantom과 두경부에 병변이 있는 방사선 치료 환자 10명을 대상으로 하였다. Phantom을 대상으로 한 C-RAD system의 셋업 에러 평균과 표준편차는 X축 $0.55{\pm}0.51mm$, Y축 $-0.2{\pm}0.523mm$, Z축 $-0.85{\pm}0.587mm$로 나타났으며, 환자를 대상으로 한 실험에서는 X축 $-0.05{\pm}0.621mm$, Y축 $0.075{\pm}0.755mm$, Z축 $-1.025{\pm}0.617mm$로 산출되어, 전반적으로 3-laser system에 비해 셋업의 정확도가 우수하였으나, Z축의 에러 발생률은 C-RAD system이 약간 높게 나타났다. 체표면 윤곽 스캐닝 시스템은 두경부의 방사선 치료 시에 정확한 포지셔닝을 유도함으로써 셋업오차를 최소화 시키는데 기여할 것으로 사료된다.F