Development of a tau-V337M mouse model using CRISPR/Cas9 system and enhanced ssODN-mediated recombination / 生物工程学报

The generation of a tau-V337M point mutation mouse model using gene editing technology can provide an animal model with fast disease progression and more severe symptoms, which facilitate the study of pathogenesis and treatment of Alzheimer's disease (AD). In this study, single guide RNAs (sgRNA) and single-stranded oligonucleotides (ssODN) were designed and synthesized in vitro. The mixture of sgRNA, Cas9 protein and ssODN was microinjected into the zygotes of C57BL/6J mice. After DNA cutting and recombination, the site homologous to human 337 valine (GTG) in exon 11 was mutated into methionine (ATG). In order to improve the efficiency of recombination, a Rad51 protein was added. The female mice mated with the nonvasectomy male mice were used as the surrogates. Subsequently, the 2-cell stage gene edited embryos were transferred into the unilateral oviduct, and the F0 tau-V337M mutation mice were obtained. Higher mutation efficiency could be obtained by adding Rad51 protein. The F0 tau-V337M point mutation mice can pass the mutation on to the F1 generation mice. In conclusion, this study successfully established the first tau-V337M mutation mouse by using Cas9, ssODN and Rad51. These results provide a new method for developing AD mice model which can be used in further research on the pathogenesis and treatment of AD.

Expression of DNA Damage Response Proteins and Associations with Clinicopathologic Characteristics in Chinese Familial Breast Cancer Patients with BRCA1/2 Mutations / 한국유방암학회지

PURPOSE: The characteristic expression of DNA damage response proteins in familial breast cancers with BRCA1, BRCA2, or non-BRCA1/2 mutations has not been analyzed in Chinese patients. Our study aimed to assess the differential expression of microcephalin 1 (BRIT1), ATM serine/threonine kinase (ATM), checkpoint kinase 2 (CHEK2), BRCA1, RAD51 recombinase (RAD51), and poly (ADP-ribose) polymerase 1 (PARP-1) and establish the profile of Chinese familial breast cancers with different mutation status. METHODS: We constructed five tissue microarrays from 183 familial breast cancer patients (31 with BRCA1 mutations; 14 with BRCA2 mutations, and 138 with non-BRCA1/2 mutations). The DNA response and repair markers used for immunohistochemistry analysis included BRIT1, ATM, CHEK2, BRCA1, RAD51, and PARP-1. The expressions of these proteins were analyzed in BRCA1/2 mutated tumors. The association between pathologic characteristics with BRCA1/2 mutation status was also analyzed. RESULTS: In familial breast cancer patients, BRCA1 mutated tumors were more frequent with high nuclear grade, estrogen receptor/progesterone receptor/human epidermal growth factor receptor 2 negative, low Ki-67, and positive CK5/6. BRCA1 mutated tumors had lower CHEK2 and higher cytoplasmic BRIT1 expression than BRCA2 and non-BRCA1/2 mutation tumors. BRCA2-associated tumors showed higher CHEK2 and cytoplasmic RAD51 expression than those in other groups. Nuclear PARP-1 expression in BRCA1/2-associated tumors was significantly higher than in non-BRCA1/2 mutation tumors. Moreover, we found quite a few of negative PARP-1 expression cases in BRCA1/2 mutated groups. CONCLUSION: The clinicopathologic findings of BRCA1-associated Chinese familial breast cancers were similar to the results of other studies. Chinese familial breast cancer patients with BRCA1/2 mutations might have distinctive expression of different DNA damage response proteins. The reduced expression of PARP-1 in Chinese BRCA1/2 mutated breast cancer patients could influence the therapeutic outcome of PARP-1 inhibitors.

Expression of PH Domain Leucine-rich Repeat Protein Phosphatase, Forkhead Homeobox Type O 3a and RAD51, and their Relationships with Clinicopathologic Features and Prognosis in Ovarian Serous Adenocarcinoma / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ovarian serous adenocarcinoma can be divided into low- and high-grade tumors, which exhibit substantial differences in pathogenesis, clinicopathology, and prognosis. This study aimed to investigate the differences in the PH domain leucine-rich repeat protein phosphatase (PHLPP), forkhead homeobox type O 3a (FoxO3a), and RAD51 protein expressions, and their associations with prognosis in patients with low- and high-grade ovarian serous adenocarcinomas.</p><p><b>METHODS</b>The PHLPP, FoxO3a, and RAD51 protein expressions were examined in 94 high- and 26 low-grade ovarian serous adenocarcinomas by immunohistochemistry. The differences in expression and their relationships with pathological features and prognosis were analyzed.</p><p><b>RESULTS</b>In high-grade serous adenocarcinomas, the positive rates of PHLPP and FoxO3a were 24.5% and 26.6%, while in low-grade tumors, they were 23.1% and 26.9%, respectively (P < 0.05 vs. the control specimens; low- vs. high-grade: P > 0.05). The positive rates of RAD51 were 70.2% and 65.4% in high- and low-grade serous adenocarcinomas, respectively (P < 0.05 vs. the control specimens; low- vs. high-grade: P > 0.05). Meanwhile, in high-grade tumors, Stage III/IV tumors and lymph node and omental metastases were significantly associated with lower PHLPP and FoxO3a and higher RAD51 expression. The 5-year survival rates of patients with PHLPP- and FoxO3a-positive high-grade tumors (43.5% and 36.0%) were significantly higher than in patients with PHLPP-negative tumors (5.6% and 7.2%, respectively; P< 0.05). Similarly, the 5-year survival rate of RAD51-positive patients (3.0%) was significantly lower than in negative patients (42.9%; P< 0.05). In low-grade tumors, the PHLPP, FoxO3a, and RAD51 expressions were not significantly correlated with lymph node metastasis, omental metastasis, Federation of Gynecology and Obstetrics stage, or prognosis.</p><p><b>CONCLUSIONS</b>Abnormal PHLPP, FoxO3a, and RAD51 protein expressions may be involved in the development of high- and low-grade ovarian serous adenocarcinomas, suggesting common molecular pathways. Decreased PHLPP and FoxO3a and increased RAD51 protein expression may be important molecular markers for poor prognosis, and RAD51 may be an independent prognosis factor, of high-grade, but not low-grade, ovarian serous adenocarcinomas.</p>

Mutaciones del gen RAD51 en el cáncer familiar de ovario: revisión de la literatura / RAD51 gene mutations in familial ovarian cancer: literature review

ANTECEDENTES: En los últimos 15 años, el carcinoma familiar de ovario, ha sido atribuido en su mayoría a mutaciones en BRCA 1 y 2. Sin embargo, aproximadamente el 25% de los nuevos casos se asocian a mutaciones aisladas de genes implicados en el mecanismo de reparación del ADN por recombinación homóloga. Mutaciones monoalélicas de RAD51 han sido identificadas en pacientes con historia de carcinoma mama y ovario, tamizaje negativo para BRCA 1 y 2, y por lo menos con un caso de carcinoma de ovario en el linaje. OBJETIVO: Describir las mutaciones en el complejo RAD51 con el fin de identificar su papel en el cáncer de ovario familiar. MÉTODO: Se realizó una búsqueda de la literatura en bases de datos de los últimos 10 años con los siguientes términos MeSH: "RAD51", "ovarian cancer" "ovarian neoplasm", "family ovarian cancer". RESULTADOS: Se encontró una prevalencia de la mutación en genes del complejo RAD51 que varía entre 0,2% y 2,5%, según la etnia estudiada, siendo una de las causas de tumores serosos de ovario de alto grado en mujeres entre los 57 y 60 años. CONCLUSIÓN: Mutaciones de RAD51 en pacientes negativas para mutaciones de BRCA 1 y 2, se asocian al síndrome familiar mama-ovario, con un aumento del riesgo para carcinoma de ovario, pero sin modificaciones para el carcinoma de mama.

BACKGROUND: In the last fifteen years, familiar ovarian carcinoma has been related to BRCA 1 and 2 mutations. However, 25% of new cases of ovarian neoplasm are explained by isolated genes involved in the mechanism of homologous recombination. Patients with family history of ovarian and breast carcinoma, negative for BRCA mutations and at least with one case of invasive ovarian carcinoma have been identify with monoallelic mutations in RAD51. OBJECTIVE: To describe mutations on RAD51 complex, in order to identify its role in familiar ovarian cancer. METHODOLOGY: A systematic review of the literature of the last ten years involving the main data bases and using the following MeSH terms: "RAD51", "ovarian cancer", "ovarian neoplasm", "family ovarian cancer". RESULTS: Prevalence reported for RAD51 mutation is between 0.2 and 2.5%, associated with the ethnicity of the population involved. Also is considered a cause for high grade serous ovarian carcinoma in women between 57 and 60 years old. RAD51C and RAD51D germ line mutations are related to ovarian-breast hereditary syndrome, in negative population for BRCA 1 and 2 mutations. CONCLUSION: Patients with RAD51 mutations, negative for BRCA mutation are associated with ovarian-breast cancer syndrome increasing the risk just for ovarian cancer.

Relationship between RAD51-G135C and XRCC3-C241T Single Nucleotide Polymorphisms and Onset of Acute Myeloid Leukemia / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between RAD51-G135C and XRCC3-C241T single nucleotide polymorphisms and onset of acute myeloid leukemia (AML).</p><p><b>METHODS</b>The study was performed in 2 groups: AML patient group and normal person group as control group. Genomic DNA was extracted from peripheral blood cells of 545 AML patients and 1 034 normal persons. Genotypes of RAD51-G135C and XRCC3-C241T were analyzed by TaqMan probe technology and the ralatienship between RAD51-G135C/XRCC3-C241T polymorphisms and onset of acute myeloid leukemia was investigated.</p><p><b>RESULTS</b>Compared with the control group, RAD51-G135C homozygous mutant (CC) could significantly increase the risk of AML patients (OR=3.07), and there was no statistical relationship between heterozygous mutant (GC) of RAD51-G135C and onset of AML. There was no statistical relationship between homozygous mutant (TT) of XRCC3-C241T and onset of AML, and the XRCC3-C241T heterozygous mutation type (CT) increased the risk of AML patients (OR=0.66).</p><p><b>CONCLUSION</b>RAD51-G135C homozygous mutant and XRCC3-C241T heterozygous mutation significantly increase the risk of the AML onset, which can provide more predictive value for incidence of AML.</p>

miR-506: a regulator of chemo-sensitivity through suppression of the RAD51-homologous recombination axis / 癌症

Ovarian carcinoma is the most lethal gynecologic malignancy. Resistance to platinum is considered the major problem affecting prognosis. Our recent study established that microRNA-506 (miR-506) expression was closely associated with progression-free survival and overall survival in two independent patient cohorts totaling 598 epithelial ovarian cancer cases. Further functional study demonstrated that miR-506 could augment the response to cisplatin and olaparib through targeting RAD51 and suppressing homologous recombination in a panel of ovarian cancer cell lines. Systemic delivery of miR-506 in an orthotopic ovarian cancer mouse model significantly augmented the cisplatin response, thus recapitulating the clinical observation. Therefore, miR-506 plays a functionally important role in homologous recombination and has important therapeutic value for sensitizing cancer cells to chemotherapy, especially in chemo-resistant patients with attenuated expression of miR-506.

Estudo dos mecanismos moleculares do reparo de quebra de duplas fitas no DNA mitocondrial / Study of the molecular mechanisms of double-strand break repair in mitochondrial DNA

O DNA está constantemente exposto a danos causados tanto por agentes endógenos quanto exógenos. Estes podem causar diferentes tipos de lesões incluindo modificações de bases e do açúcar, além de quebras de fitas simples ou duplas. As quebras de duplas fitas, quando comparadas às demais, constituem as mais citotóxicas e podem resultar em deleções no DNA e instabilidade genética. Deleções no DNA mitocondrial (mtDNA) causam diversas doenças e estão envolvidas no processo de envelhecimento. No núcleo, as quebras de duplas fitas no DNA podem ser reparadas por recombinação homóloga (HR), ligação de pontas não homólogas (NHEJ) e anelamento de fita simples (SSA). No entanto, em mitocôndrias de células de mamíferos, o reparo de quebras de duplas fitas ainda não foi completamente caracterizado. Experimentos in vitro usando extratos mitocondriais de células de roedores mostraram que estes são capazes de reparar essas quebras, no entanto pouco é sabido sobre quais proteínas são responsáveis por cada etapa de reparo, bem como sua implicação na manutenção da integridade do genoma mitocondrial. Sendo assim, nesse trabalho investigamos a localização e função mitocondrial das proteínas ATM, Rad51, Rad52, Ku70/86 e DNA-PKCs, que são sabidamente envolvidas em reparo de quebras de duplas fitas no núcleo. Para identificar essas proteínas em mitocôndrias de células de mamíferos, mitocôndrias foram isoladas a partir de células da linhagem HEK293T, usando centrifugação diferencial seguida por gradiente de Percoll. Para as proteínas de recombinação homóloga, ATM e Rad51, imunodetectamos isoformas semelhantes em todos os compartimentos celulares. Já para a proteína Rad52 o mesmo anticorpo imunodetectou duas bandas distintas na mitocôndria ao passo que no núcleo foram quatro. Além disso, verificamos que baixos níveis de proteína Rad52, induzidos pela expressão de shRNA (short hairping RNA) específico, resultam em diminuição do número de cópias de mtDNA bem como acúmulo de deleções no genoma mitocondrial. Para as proteínas de NHEJ, DNA-PKCs e a subunidade Ku70, identificamos isoformas semelhantes em todos os compartimentos celulares. Já para a subunidade 86 do heterodímero Ku70/86 o anticorpo detectou, somente em mitocôndrias, uma banda menor de 50 kDa, a qual difere na região N-terminal da subunidade detectada no núcleo (86 KDa). Experimentos de co-imunprecitação de proteínas mostraram que essa isoforma menor compõe o heterodímero mitocondrial juntamente com a subunidade 70 (mtKu70/50) e que esse interage com DNA ligase III mitocondrial. Nossos resultados também mostraram que a estabilidade proteica de mtKu70/50 é regulada por ATM. Tratamento das células com peróxido de hidrogênio, que induz quebras de duplas fitas, aumentou a associação do heterodímero mtKu70/50 com o mtDNA, de forma independente de aumento da concentração proteica intra-mitocondrial. Já a diminuição dos níveis proteicos de Ku, induzida através de shRNA, resultou em diminuição do número de cópias de mtDNA e acumulo de danos nesse genoma. Extratos mitocondriais de células knockdown para Ku apresentaram menor atividade de reparo NHEJ em um ensaio in vitro, sugerindo que o acúmulo de danos nestas células é provavelmente devido a deficiências na via de NHEJ. Em conjunto, nossos dados sugerem que tanto HR quanto NHEJ operam em mitocôndrias. Além disso, a via de NHEJ mitocondrial utiliza o heterodímero mitocondrial Ku70/50 o qual está envolvido na manutenção do mtDNA. Ademais, nossos resultados mostram uma grande conservação molecular e funcional entre as vias de reparo de NHEJ e HR no núcleo e na mitocôndria, o que reforça sua importância para a manutenção da estabilidade genômica mitocondrial e, provavelmente a função mitocondrial

DNA is constantly exposed to damaging agents from both endogenous and exogenous sources. These can cause different types of DNA lesions that include base and sugar modifications and single and double strand breaks. DNA doublestrand breaks (DSBs) are among the most cytotoxic DNA lesions, which can result in deletions and genetic instability. Deletions in the mitochondrial DNA (mtDNA) cause numerous human diseases and drive normal aging. DSBs in the nuclear DNA are repaired by non-homologous DNA end joining (NHEJ), homologous recombination (HR) or Single Strand Annealing (SSA). Yet, repair of DSBs in mammalian mitochondria has not been fully characterized. Mitochondrial extracts from rodent cells are proficient in ligating DNA ends in vitro, but little is known about which proteins are responsible for each enzymatic step and its implication in mitochondrial genome maintenance. Thus, we investigated mitochondrial localization and function of DSBR (double strand break repair) proteins ATM, Rad51, Rad52, the Ku70/86 heterodimer and DNA-PKCs.To identify DSBR proteins in mammalian mitochondria, highly purified mitochondria from HEK293T cells were isolated using differential centrifugation followed by Percoll gradient. For HR proteins, we detected similar isoforms for ATM and Rad51 proteins in all cellular compartments. Two mitochondriaspecific isoforms of Rad52 were detected, while the same antibody detected four isoforms in the nucleus. In addition, lower Rad52 protein levels, induced by specific shRNA expression, result in decreased mtDNA copy number and accumulation of deleted mitochondrial genomes. For NHEJ proteins, similar isoforms of DNA-PKcs and the Ku70 subunit were detected in all cellular compartments. On the other hand, antibodies against the Ku86 subunit detected a smaller band in mitochondrial extracts (50 KDa), lacking the N-terminal region of the canonical isoform detected in the nucleus (86 KDa). The mitochondrial Ku70/50 heterodimer interacts with mitochondrial DNA ligase III, suggesting a role in DSBR. Moreover, stability of the mtKu heterodimer is regulated by ATM. Hydrogen peroxide treatment, which induces DSBs, increases mtKu70/50 association with the mtDNA and cells with reduced Ku levels, also induced by shRNA transfection, have lower mtDNA copy number and accumulate mtDNA damage. Moreover, mitochondrial extracts from Ku knockdown cells show lower NHEJ repair activity in an in vitro assay, suggesting that damage accumulation in these cells is likely due to deficiencies in NHEJ. Together, our data suggest that both HR and NHEJ operate in mitochondria. Also, mtNHEJ requires the Ku heterodimer and is involved in mtDNA maintenance. Moreover, our results indicate that there is a significant molecular and functional conservation between NHEJ and HR repair pathways in the nucleus and in mitochondria, which reinforces their importance for maintenance of mitochondrial genomic stability and, likely mitochondrial function

Comparative study on functional characters of MCF7 and HCC1937 cell lines in response to DNA damage / 中华预防医学杂志

<p><b>OBJECTIVE</b>The functional characters of MCF7 and HCC1937 cell lines were compared through the activity of BRCA1 and p53 following DNA damage in order to provide more research evidence for the related studies in both breast cancer cell lines.</p><p><b>METHODS</b>The protein level of BRCA1 and p53 in two breast cancer cell lines and the protein level of BRCA1 in MCF7, HCC1937 and HCC1937 wtBRCA1 breast cancer cell lines treated with 10Gy after 1 h, 4 h or 8 h were detected by western blotting analysis. The distribution and foci formation of BRCA1 in the cells were observed through immunostaining assay and the percentage of BRCA1 or Rad51 foci formation after ionizing radiation was calculated. Cell cycle profiling was analyzed using flow cytometry.</p><p><b>RESULTS</b>Most of BRCA1 and p53 localized in nucleus, and both proteins responded to DNA damage in MCF7 cells. In MCF7 cells,BRCA1 and Rad51 foci formation respectively increased to (59.40 ± 3.66)% from (11.80 ± 3.51)% (t = 16.26, P < 0.05) and (73.90 ± 8.66) % from (16.70 ± 3.76) % (t = 10.49, P < 0.05) after 10 Gy 8 h ; p53 and p21 protein level was further separately induced and enhanced to (82.54 ± 1.04) from (23.75 ± 0.51) (t = 87.90, P < 0.05) and (90.95 ± 1.13) from (50.19 ± 0.89) ( t = 49.11, P < 0.05) after 10 Gy 8 h; and the cells were accumulated in G1 phase. In contrast to MCF7, in HCC1937 cell line, both of BRCA1 and p53 were defective in nucleus since both proteins were mutated; in response to DNA damage, BRCA1 foci formation was not found, p53 and p21 was not induced; there was no cell accumulation in both of G1-S and G2-M phases. However, after complementation of wild-type BRCA1 in HCC1937 cells, DNA damage-induced Rad51 foci formation increased to (61.70 ± 4.03) % from (6.22 ± 2.27) % (t = 20.78, P < 0.05) and accumulation of cells in G2-M phase was also restored after 10 Gy 8h , which was similar to that of in MCF7 cells.</p><p><b>CONCLUSIONS</b>We have identified that BRCA1 and p53 have dramatically different functions in MCF7 and HCC1937 cell lines in response to DNA damage.</p>

Relationship between RAD51-G135C/XRCC3-C241T polymorphisms and development of acute myeloid leukemia with recurrent chromosome translocation / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between DNA homologous recombination (HR) repair genes RAD51-G135C/XRCC3-C241T polymorphisms and development of acute myeloid leukemia (AML) with recurrent chromosome translocation.</p><p><b>METHODS</b>Genomic DNA was extracted from bone marrow cells of 625 de novo AML patients and peripheral blood cells of 806 patient family members and 704 unrelated volunteers. Genotypes of RAD51-G135C and XRCC3-C241T were analyzed by PCR-RFLP. Cell lines with genotypes differed from XRCC3-C241T were selected and irradiated in vitro. The CBFβ-MYH11 fusion gene was detected by TaqMan real-time PCR.</p><p><b>RESULTS</b>The XRCC3-C241T variant (C/T + T/T) showed 6.22-fold and 6.99-fold increase in the risk of developing the AML with inv(16)/t(16;16)/CBFβ-MYH11 as compared with the volunteer and family member controls respectively; the RAD51-G135C homozygote-type (C/C) variant showed 0.87-fold (P = 0.010) and 1.15-fold (P = 0.001) respectively increase in the risk of this subtype AML. In the irradiated group, the CBFβ-MYH11 mRNA level in HL-60 cells was 59.49 times increased than that in KG1a cells. However, the RAD51-G135C and XRCC3-C241T variants had no correlations with the risk of development of t(15;17)/PML-RARα(+)AML, t(8;21)/AML1-ETO(+) AML and 11q23 AML subtypes.</p><p><b>CONCLUSION</b>The XRCC3-C241T variant and the RAD51-G135C homozygote-type significantly increase the risk of the development of AML with inv(16)/t(16;16)/CBFβ-MYH11.</p>

Relationship between RAD51-g135C and XRCC3-C241T polymorphisms and prognosis of inv (16)/ t(16;16) (CBFbeta-MYH11) acute myeloid leukemia / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the impact of polymorphisms of DNA homologous recombination (HR) repair genes RAD51-G135C and XRCC3-C241T on the prognosis of acute myeloid leukemia (AML) with inv(16)/t(16;16)(CBFbeta-MYH1).</p><p><b>METHODS</b>One hundred and three de novo inv(16)/t(16;16) (CBFbeta-MYH11) AML patients were followed-up and retrospectively analyzed. Polymorphisms of RAD51-G135C and XRCC3-C241T were detected by PCR-RFLP. The prognostic factors,including sex, age, white blood cell count, platelet count, hemoglobin level, karyotype, KIT mutation, RAD51-G135C and XRCC3-C241T polymorphisms at diagnosis, for complete remission (CR) achievement, overall survival (OS) and relapse-free survival (RFS) were analyzed by univariate and multivariate analyses.</p><p><b>RESULTS</b>The median follow-up of all patients was 28 (1 - 106) months. The overall CR rate was 92.2%. The estimated 5-year OS and RFS rates were 43.6% (95% CI 37.7% - 49.5%) and 26.4% (95% CI 21.1% - 31.7%), and the median OS and RFS were 53 (95% CI 133.4 - 72.7) and 27 (95% CI 22.9 - 31.1) months, respectively. In multivariate analysis, higher WBC (P = 0.004) and older than 30 years of age (P = 0.035) were independent poor factors for CR achievement, the XRCC3-241T variant (P = 0.007) and higher WBC (P = 0.009) were independent poor factors for 5-year RFS, and higher WBC (P = 0.002) and trisomy 8 (P = 0.035) were independent poor factors for 5-year survival. Polymorphism of RAD51-G135C had no significant impact on the prognosis.</p><p><b>CONCLUSION</b>The XRCC3-241T variant is an independent poor prognostic factor for AML with inv(16)/t(16;16)/CBFbeta-MYH11.</p>

Relationship between NQO1C(609T), RAD51(G135C), XRCC3(C241T) single nucleotide polymorphisms and acute lymphoblastic leukemia / 中国实验血液学杂志

This study was purposed to investigate the relationship between NQO1C(609T), RAD51(G135C), XRCC3(C241T) single nucleotide polymorphisms and incidence of acute lymphoblastic leukemia (ALL). NQO1C(609T), RAD51(G135C), XRCC3(C241T) genotypes were detected by PCR-RFLP in 170 patients with de novo ALL and 458 normal persons as control. The results indicated that the genotype ratio of NQO1C(609T), RAD51(G135C) and XRCC3(C241T) in single genotype analysis showed no statistical difference between ALL patients and normal controls, which suggested that the single genotype affect onset of ALL without statistical significance. In combined genotype analysis, presence of both variants for NQO1C(609T) and RAD51(G135C) increased onset risk of ALL with myeloid antigen positive and with balanced translocation (OR value 5.553 and 2.618 respectively); the presence of homozygosity variant for NQO1C(609T) increased onset risk of ALL in the country-children (OR = 2.541). In conclusion, the combined effect of NQO1C(609T), RAD51(G135C) and XRCC3(C241T) genotypes may promote occurrence of ALL, which suggests that the combined analysis of 3 genotypes has more predictive significance for ALL than single genotype analysis.

Expression of RAD51 in carcinomas of cancer of larynx and its clinical significance / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate the expression and clinical significance of RAD51 in laryngocarcinoma.@*METHOD@#The expression of RAD51 in laryngocarcinoma and polyp of vocal cord tissues were determined by immunohistochemical staining. The results were analyzed and compared with the clinical stage, lymph node metastasis and pathologic grade.@*RESULT@#(1) The expression of RAD51 in laryngocarcinoma group was extremely stronger than that in polyp of vocal cord group (P < 0.01). (2) There was significant difference for RAD51 expression in cancer cells between earlier clinical stage group and advanced clinical stage group (P < 0.01). (3) There was significant difference for RAD51 expression in different pathologic grades (P < 0.05). (4) There was also significant difference for RAD51 expression between groups with and without lymph node metastasis.@*CONCLUSION@#RAD51 may play a critical role in tumorigenesis of laryngocarcinoma. RAD51 may be a potential marker for clinical diagnosis and treatment of Laryngocarcinoma. It may be significant in predicting clinical stage, pathologic grade and metastasis.

Structural characterization of 5' flanking regulatory region of DNA repair gene Rad51 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To clarify the regulatory elements of Rad51 gene in its 5'flanking region.</p><p><b>METHODS</b>Various constructs were obtained by cloning different DNA fragments into pGL3 reporter vector. These constructs were then introduced into osteosarcoma cell line U2-OS by calcium phosphate method for transient expression of reporter gene, and luciferase activities were measured by luciferase assay.</p><p><b>RESULTS</b>Cells transfected with pGL3 constructs containing fragment -964 to +1430 and -733 to +1430 showed high luciferase activities. Obvious elevation of luciferase activities was also observed in cells transfected with pGL3 constructs containing four shorter derivative fragments -964 to -412, -746 to -412, -651 to -412 and -536 to -412. The highest luciferase activities were measured in transfected cells with plasmids containing fragment -964 to -412, and the lowest were in transfected cells with plasmids containing fragment -536 to -412. Luciferase activities in transfected cells with plasmids containing fragment -651 to -412 were higher than that in transfected cells with plasmids containing fragment -746 to -412.</p><p><b>CONCLUSION</b>It is believable that the basic transcription-promoting element (promoter) for Rad51 gene resides between -536 to -412, and two transcription-enhancing elements (enhancer) or binding sites of positive transcription factors reside between -651 to -536 and -964 to -746, whereas one transcription-inhibiting element (silencer) or binding site of negative transcription factor may reside between -746 to -651.</p>