The role of UV-DDB in processing 8-oxoguanine during base excision repair.

Recent data from our laboratory has shown that the nucleotide excision repair (NER) proteins UV-damaged DNA-binding protein (UV-DDB), xeroderma pigmentosum group C (XPC), and xeroderma pigmentosum group A (XPA) play important roles in the processing of 8-oxoG. This review first discusses biochemical studies demonstrating how UV-DDB stimulates human 8-oxoG glycosylase (OGG1), MUTYH, and apurinic/apyrimidinic (AP) endonuclease (APE1) to increase their turnover at damage sites. We further discuss our single-molecule studies showing that UV-DDB associates with these proteins at abasic moieties on DNA damage arrays. Data from cell experiments are then described showing that UV-DDB interacts with OGG1 at sites of 8-oxoG. Finally, since many glycosylases are inhibited from working on damage in the context of chromatin, we present a working model of how UV-DDB may be the first responder to alter the structure of damage containing-nucleosomes to allow access by base excision repair (BER) enzymes.

Polymorphism in the TP63 gene imparts a potential risk for leukemia in the North Indian population.

BACKGROUND: The role of single nucleotide polymorphism rs10937405 (C>T) of the TP63 gene in cancer including leukemia has previously been studied in different world populations; however, the role of this variant in leukemia in the North Indian population of Jammu and Kashmir is still unknown. OBJECTIVES: In the present study, we investigated the association of genetic variant rs10937405 with leukemic in the Jammu and Kashmir population. METHODS: A total of 588 subjects, (188 cases and 400 controls) were recruited for the study. The rs10937405 variant was genotyped by using the real-time based TaqMan assay. RESULTS: A statistically significant association was observed between the rs10937405 and leukemia [OR of 1.94 (95% CI 1.51-2.48), p=1.2x10-6]. CONCLUSION: The current study concludes that the rs10937405 variant is a risk factor for the development of leukemia in the population of Jammu and Kashmir, North India. However, it would be interesting to explore the contribution of this variant in other cancers as well. Our findings will help in the development of diagnostic markers for leukemia in the studied population and potentially for other North Indian populations.

MassArray analysis of genomic susceptibility variants in ovarian cancer.

Ovarian cancer (OC), a multifaceted and genetically heterogeneous malignancy is one of the most common cancers among women. The aim of the study is to unravel the genetic factors associated with OC and the extent of genetic heterogeneity in the populations of Jammu and Kashmir (J&K).Using the high throughput Agena MassARRAY platform, present case control study was designed which comprises 200 histopathological confirmed OC patients and 400 age and ethnicity matched healthy controls to ascertain the association of previously reported eleven single nucleotide polymorphisms (SNPs) spread over ten genes (DNMT3A, PIK3CA, FGFR2, GSTP1, ERCC5, AKT1, CASC16, CYP19A1, BCL2 and ERCC1) within the OC population of Jammu and Kashmir, India. The association of each variant was estimated using logistic regression analyses. Out of the 11 SNPs the odds ratio observed for three SNPs; rs2699887 was (1.72 at 95% CI: 1.19-2.48, p = 0.004), rs1695 was (1.87 at 95% CI: 1.28-2.71, p = 0.001), and rs2298881 was (0.66 at 95% CI: 0.46-0.96, p = 0.03) were found significantly associated with the OC after correction with confounding factors i.e. age & BMI. Furthermore, the estimation of interactive analyses was performed and odds ratio observed was 2.44 (1.72-3.47), p value < 0. 001 suggests that there was a strong existence of interplay between the selected genetic variants in OC, which demonstrate that interactive analysis highlights the role of gene-gene interaction that provides an insight among multiple little effects of various polymorphisms in OC.

MassARRAY-based single nucleotide polymorphism analysis in breast cancer of north Indian population.

BACKGROUND: Breast Cancer (BC) is associated with inherited gene mutations. High throughput genotyping of BC samples has led to the identification and characterization of biomarkers for the diagnosis of BC. The most common genetic variants studied are SNPs (Single Nucleotide Polymorphisms) that determine susceptibility to an array of diseases thus serving as a potential tool for identifying the underlying causes of breast carcinogenesis. METHODS: SNP genotyping employing the Agena MassARRAY offers a robust, sensitive, cost-effective method to assess multiple SNPs and samples simultaneously. In this present study, we analyzed 15 SNPs of 14 genes in 550 samples (150 cases and 400 controls). We identified four SNPs of genes TCF21, SLC19A1, DCC, and ERCC1 showing significant association with BC in the population under study. RESULTS: The SNPs were rs12190287 (TCF21) having OR 1.713 (1.08-2.716 at 95% CI) p-value 0.022 (dominant), rs1051266 (SLC19A1) having OR 3.461 (2.136-5.609 at 95% CI) p-value 0.000000466 (dominant), rs2229080 (DCC) having OR 0.6867 (0.5123-0.9205 at 95% CI) p-value 0.0116 (allelic) and rs2298881 (ERCC1) having OR 0.669 (0.46-0.973 at 95% CI), p-value 0.035 (additive) respectively. The in-silico analysis was further used to fortify the above findings. CONCLUSION: It is further anticipated that the variants should be evaluated in other population groups that may aid in understanding the genetic complexity and bridge the missing heritability.

Genetic polymorphism of hOGG1 ser326cys and its association with breast cancer in Jammu and Kashmir.

BACKGROUND: 8-Oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) is a potent DNA damage marker that leads to cellular oxidative stress. It is a DNA-repair enzyme that participates in "8-oxodG" DNA adducts removal. Previous studies show weak associations of rs1052133 (hOGG1) in breast cancer patients of Northern India. We performed this study to explore the variant rs1052133 (hOGG1) with breast in the population of Jammu and Kashmir (J and K). METHOD: A polymerase chain reaction-restriction fragment length polymorphism -based single-nucleotide polymorphism (SNP) genotypic study was carried out in peripheral blood samples of 165 breast cancer patients and 200 healthy controls, using specific primers. Sanger sequencing verified the results. RESULTS: hOGG1-Ser326Cys polymorphism occurred frequently in cases as compared with controls. Data were evaluated by SPSS V.13 software, following Hardy-Weinberg equilibrium (P = 0.002 at OR 2.57; 95% CI [1.68-3.93]), which showed that the SNP rs1052133 had a significant association with increased risk of breast cancer. CONCLUSION: Overall, the results of this analysis show that the hOGG1-Ser326Cys polymorphism may be associated with an increased risk for breast cancer in the J and K population.

ANKLE1 as New Hotspot Mutation for Breast Cancer in Indian Population and Has a Role in DNA Damage and Repair in Mammalian Cells.

Breast cancer has replaced cervical cancer as being the most common and having the highest mortality among women in India. ANKLE gene is conserved among organisms during evolutionary succession and is a member of LEM family proteins in lower metazoans and is involved in critical functions in the nuclear architecture, gene expression and cell signaling. ANKLE1 is the human orthologous of LEM-3 and is involved in DNA damage response and DNA repair. Whole Exome Sequencing (WES) of paired breast cancer samples was performed and ANKLE1 was found to be a new possible hotspot for predisposition of breast cancer. The mass array genotyping for breast cancer variant rs2363956 further confirmed the ANKLE1 association with the studied population of breast cancer. To elucidate the role of ANKLE1 in DNA damage, it was knocked down in MCF-7 breast cancer cell line and the expression of γH2AX was assessed. ANKLE1 knockdown cells displayed elevated levels of γ-H2AX foci in response to the cisplatin induced replication stress. The localization pattern of ANKLE1 further emphasized the role of ANKLE1 in DNA repair process. We observed that ANKLE1 is required for maintaining genomic stability and plays a role in DNA damage and repair process. These findings provided a molecular basis for the suspected role of ANKLE1 in human breast cancer and suggested an important role of this gene in controlling breast cancer development among women in India.

DNA base excision repair genes variants rs25487 (X-ray repair cross-complementing 1) and rs1052133 (human 8-oxoguanine glycosylase 1) with susceptibility to ovarian cancer in the population of the Jammu region, India.

BACKGROUND: Ovarian cancer is highly prevalent in the population of Jammu, in India; the ovarian cancer ranks third among other types of cancer prevalent in females. However, association studies on ovarian cancer are lacking in this region. We aimed to investigate the disease susceptible variants rs1052133 (human 8-oxoguanine glycosylase 1 [hOGG1]) and rs25487 (X-ray repair cross-complementing 1 [XRCC1]) with ovarian cancer in population of Jammu, India. MATERIALS AND METHODS: The study conducted in the Shri Mata Vaishno Devi University is a 3-year study which included a total of 280 well-characterized samples (130 ovarian cancer cases and 150 healthy controls). hOGG1 and XRCC1 polymorphisms were determined by polymerase chain reaction-based restriction fragment length polymorphism, and these genotyping results were confirmed by Sanger sequencing. Hardy-Weinberg equilibrium for both single-nucleotide polymorphisms (SNPs) was assessed using the Chi-square test. The allele and genotype-specific risks were estimated by odds ratios with 95% confidence intervals. RESULTS: In this preliminary study, SNP rs1052133 showed protection with ovarian cancer (P = 0.042). The SNP rs25487 was not found associated with ovarian cancer (P = 0.271). CONCLUSION: Our results indicate that the G allele of rs1052133 imparts protection to the population whereas variant rs25487 was not associated with ovarian cancer in population from the Jammu region, indicating that larger sample size is needed for further statistical validation. Further, association of other SNPs in these genes should also be carried out as their role cannot be ruled out.