XRCC1 rs1799782 (C194T) polymorphism correlated with tumor metastasis and molecular subtypes in breast cancer

Genetic markers of cardiac autonomic neuropathy in the Kazakh population

BACKGROUND

Cardiac autonomic neuropathy (CAN) is a complication of diabetes mellitus (DM) that increases the risk of morbidity and mortality by disrupting cardiac innervation. Recent evidence suggests that CAN may manifest even before the onset of DM, with prediabetes and metabolic syndrome potentially serving as precursors. This study aims to identify genetic markers associated with CAN development in the Kazakh population by investigating the SNPs of specific genes.

MATERIALS AND METHODS

A case-control study involved 82 patients with CAN (cases) and 100 patients without CAN (controls). A total of 182 individuals of Kazakh nationality were enrolled from a hospital affiliated with the RSE "Medical Center Hospital of the President's Affairs Administration of the Republic of Kazakhstan". 7 SNPs of genes FTO, PPARG, SNCA, XRCC1, FLACC1/CASP8 were studied. Statistical analysis was performed using Chi-square methods, calculation of odds ratios (OR) with 95% confidence intervals (CI), and logistic regression in SPSS 26.0.

RESULTS

Among the SNCA gene polymorphisms, rs2737029 was significantly associated with CAN, almost doubling the risk of CAN (OR 2.03(1.09-3.77), p = 0.03). However, no statistically significant association with CAN was detected with the rs2736990 of the SNCA gene (OR 1.00 CI (0.63-1.59), p = 0.99). rs12149832 of the FTO gene increased the risk of CAN threefold (OR 3.22(1.04-9.95), p = 0.04), while rs1801282 of the PPARG gene and rs13016963 of the FLACC1 gene increased the risk twofold (OR 2.56(1.19-5.49), p = 0.02) and (OR 2.34(1.00-5.46), p = 0.05) respectively. rs1108775 and rs1799782 of the XRCC1 gene were associated with reduced chances of developing CAN both before and after adjustment (OR 0.24, CI (0.09-0.68), p = 0.007, and OR 0.43, CI (0.22-0.84), p = 0.02, respectively).

CONCLUSION

The study suggests that rs2737029 (SNCA gene), rs12149832 (FTO gene), rs1801282 (PPARG gene), and rs13016963 (FLACC1 gene) may be predisposing factors for CAN development. Additionally, SNPs rs1108775 and rs1799782 (XRCC1 gene) may confer resistance to CAN. Only one polymorphism rs2736990 of the SNCA gene was not associated with CAN.

Association of XRCC1 p. Arg194Trp gene polymorphism with the risk of hepatocellular carcinoma in HCV Egyptian population: A pilot case-control study

Background: Hepatocellular carcinoma (HCC) is the most common and fatal primary liver cancer. Genetic variants of DNA repair systems can reduce DNA repair capability and increase HCC risk. Objectives: This study aimed to examine, in Egyptian hepatitis C virus (HCV) patients, the relationship between the X-ray repair cross-complementing group 1 (XRCC1) rs1799782 single nucleotide polymorphism (SNP) and HCC susceptibility. Methods: We included 100 adult HCV-positive patients with HCC and 100 adult HCV-positive patients with liver cirrhosis as pathological controls. XRCC1 rs1799782 SNP genotyping was done in both groups using quantitative real-time PCR (qPCR). The distribution of genotypes in patients and controls was compared using several inheritance models. Results: We found that the CT genotype, when analyzed under both the co-dominant (OR (95 % CI): 2.147 (1.184-3.893), p = .012) and the over-dominant (OR (95 % CI): 2.055 (1.153-3.660), p = .015) models, as well as the combined CT and TT genotypes under the dominant model (OR (95 % CI) of 1.991 (1.133-3.497), p = .017), were associated with increased susceptibility to HCC. The frequency of the T allele was higher among HCC participants (32%) compared to those with cirrhosis (23.5%) and carrying the T allele increased the risk of HCC by 1.532 times, however, these associations did not reach statistical significance (p-values >0.05). Moreover, the variant T allele was associated with worse clinical manifestations and laboratory results among the HCC group, but AFP levels were not affected significantly. Conclusions: Egyptians with XRCC1 rs1799782 SNP may have a higher risk of HCV-related HCC. More extensive multi-center prospective investigations must confirm this association.

Clinical Radiobiology for Radiation Oncology

This chapter is focused on radiobiological aspects at the molecular, cellular, and tissue level which are relevant for the clinical use of ionizing radiation (IR) in cancer therapy. For radiation oncology, it is critical to find a balance, i.e., the therapeutic window, between the probability of tumor control and the probability of side effects caused by radiation injury to the healthy tissues and organs. An overview is given about modern precision radiotherapy (RT) techniques, which allow optimal sparing of healthy tissues. Biological factors determining the width of the therapeutic window are explained. The role of the six typical radiobiological phenomena determining the response of both malignant and normal tissues in the clinic, the 6R’s, which are Reoxygenation, Redistribution, Repopulation, Repair, Radiosensitivity, and Reactivation of the immune system, is discussed. Information is provided on tumor characteristics, for example, tumor type, growth kinetics, hypoxia, aberrant molecular signaling pathways, cancer stem cells and their impact on the response to RT. The role of the tumor microenvironment and microbiota is described and the effects of radiation on the immune system including the abscopal effect phenomenon are outlined. A summary is given on tumor diagnosis, response prediction via biomarkers, genetics, and radiomics, and ways to selectively enhance the RT response in tumors. Furthermore, we describe acute and late normal tissue reactions following exposure to radiation: cellular aspects, tissue kinetics, latency periods, permanent or transient injury, and histopathology. Details are also given on the differential effect on tumor and late responding healthy tissues following fractionated and low dose rate irradiation as well as the effect of whole-body exposure.

Molecular Epidemiology in Amerindians of the Brazilian Amazon Reveals New Genetic Variants in DNA Repair Genes

Native American populations from the Brazilian Amazon have a low genetic diversity and a different genetic profile when compared to people from other continents. Despite this, few studies have been conducted in this group, and there is no description of their genetic data in the various currently existent international databases. The characterization of the genomic profile of a population not only has an impact in studies of population genetics, but also helps to advance diagnostic and therapeutic response studies, leading to the optimization of clinical applicability. Genetic variations in DNA repair genes have been associated with the modulation of susceptibility to various pathologies, as well as in their prognosis and therapy. This is the first study to investigate DNA repair genes in Amerindians from the Brazilian Amazon region. We investigated 13 important DNA repair genes in the exome of 63 Native Americans, comparing our results with those found in 5 continental populations, whose data are available in the Genome Aggregation Database. Our results showed that 57 variants already described in literature were differentially distributed in the Amerindian populations in relation to the continental populations, 7 of which have significant clinical relevance. In addition, 9 new variants were described, suggesting that they are unique to these populations. Our study reinforces the understanding that the Amazonian Native American population presents a unique genetic profile, and our findings may collaborate with the creation of public policies that optimize the quality of life of these groups as well as the Brazilian population, which presents a high degree of interethnic mixing with Amerindian groups.

HKG: an open genetic variant database of 205 Hong Kong cantonese exomes

HKG is the first fully accessible variant database for Hong Kong Cantonese, constructed from 205 novel whole-exome sequencing data. There has long been a research gap in the understanding of the genetic architecture of southern Chinese subgroups, including Hong Kong Cantonese. HKG detected 196 325 high-quality variants with 5.93% being novel, and 25 472 variants were found to be unique in HKG compared to three Chinese populations sampled from 1000 Genomes (CHN). PCA illustrates the uniqueness of HKG in CHN, and the admixture study estimated the ancestral composition of HKG and CHN, with a gradient change from north to south, consistent with their geological distribution. ClinVar, CIViC and PharmGKB annotated 599 clinically significant variants and 360 putative loss-of-function variants, substantiating our understanding of population characteristics for future medical development. Among the novel variants, 96.57% were singleton and 6.85% were of high impact. With a good representation of Hong Kong Cantonese, we demonstrated better variant imputation using reference with the addition of HKG data, thus successfully filling the data gap in southern Chinese to facilitate the regional and global development of population genetics.

Haplotypes of single cancer driver genes and their local ancestry in a highly admixed long-lived population of Northeast Brazil

Admixed populations have not been examined in detail in cancer genetic studies. Here, we inferred the local ancestry of cancer-associated single nucleotide polymorphisms (SNPs) and haplotypes of a highly admixed Brazilian population. SNP array was used to genotype 73 unrelated individuals aged 80-102 years. Local ancestry inference was performed by merging genotyped regions with phase three data from the 1000 Genomes Project Consortium using RFmix. The average ancestry tract length was 9.12-81.71 megabases. Strong linkage disequilibrium was detected in 48 haplotypes containing 35 SNPs in 10 cancer driver genes. All together, 19 risk and eight protective alleles were identified in 23 out of 48 haplotypes. Homozygous individuals were mainly of European ancestry, whereas heterozygotes had at least one Native American and one African ancestry tract. Native-American ancestry for homozygous individuals with risk alleles for HNF1B, CDH1, and BRCA1 was inferred for the first time. Results indicated that analysis of SNP polymorphism in the present admixed population has a high potential to identify new ancestry-associated alleles and haplotypes that modify cancer susceptibility differentially in distinct human populations. Future case-control studies with populations with a complex history of admixture could help elucidate ancestry-associated biological differences in cancer incidence and therapeutic outcomes.

The base excision repair process: comparison between higher and lower eukaryotes

The base excision repair (BER) pathway is essential for maintaining the stability of DNA in all organisms and defects in this process are associated with life-threatening diseases. It is involved in removing specific types of DNA lesions that are induced by both exogenous and endogenous genotoxic substances. BER is a multi-step mechanism that is often initiated by the removal of a damaged base leading to a genotoxic intermediate that is further processed before the reinsertion of the correct nucleotide and the restoration of the genome to a stable structure. Studies in human and yeast cells, as well as fruit fly and nematode worms, have played important roles in identifying the components of this conserved DNA repair pathway that maintains the integrity of the eukaryotic genome. This review will focus on the components of base excision repair, namely, the DNA glycosylases, the apurinic/apyrimidinic endonucleases, the DNA polymerase, and the ligases, as well as other protein cofactors. Functional insights into these conserved proteins will be provided from humans, Saccharomyces cerevisiae, Drosophila melanogaster, and Caenorhabditis elegans, and the implications of genetic polymorphisms and knockouts of the corresponding genes.

CometChip enables parallel analysis of multiple DNA repair activities

DNA damage can be cytotoxic and mutagenic, and it is directly linked to aging, cancer, and other diseases. To counteract the deleterious effects of DNA damage, cells have evolved highly conserved DNA repair pathways. Many commonly used DNA repair assays are relatively low throughput and are limited to analysis of one protein or one pathway. Here, we have explored the capacity of the CometChip platform for parallel analysis of multiple DNA repair activities. Taking advantage of the versatility of the traditional comet assay and leveraging micropatterning techniques, the CometChip platform offers increased throughput and sensitivity compared to the traditional comet assay. By exposing cells to DNA damaging agents that create substrates of Base Excision Repair, Nucleotide Excision Repair, and Non-Homologous End Joining, we show that the CometChip is an effective method for assessing repair deficiencies in all three pathways. With these applications of the CometChip platform, we expand the utility of the comet assay for precise, high-throughput, parallel analysis of multiple DNA repair activities.

Male and female breast cancer: the two faces of the same genetic susceptibility coin

BACKGROUND

Breast cancer (BC) is the most common cancer in women. In contrast, male BC is about 100 times less common than in women, being considered a rare disease. Male BC may be a distinctive subtype of BC and available data seems to indicate that male BC has a higher dependence on genetic variants than female BC. Nevertheless, the same prognostic and predictive markers are used to determine optimal management strategies for both male and female BC. Several studies have assessed the role of genetic polymorphisms (SNPs) in DNA repair genes in female BC susceptibility. However, data on male BC is scarce. Thus, the current study aimed to assess the role of SNPs in XRCC1, MUTYH and TP53 genes in a male cohort of BC, and, in addition, compare the male data with matched results previously genotyped in female BC patients.

METHODS

The male BC cohort was genotyped through Real-Time PCR using TaqMan Assays for several SNPs previously analysed in Portuguese female BC patients.

RESULTS

The results obtained indicate significant differences in BC susceptibility between males and females for the XRCC1 rs1799782, MUTYH rs3219489 and TP53 rs1042522 and rs8064946 variants.

CONCLUSIONS

In males, XRCC1 and TP53 variants, when in heterozygosity, seem to be related with lower susceptibility for BC, contrasting with higher susceptibility for a MUTYH variant in females. These findings may help to explain the difference in incidence of BC between the two sexes.

XRCC1 Is a Promising Predictive Biomarker and Facilitates Chemo-Resistance in Gallbladder Cancer

Gallbladder cancer is a relatively uncommon human malignant tumor with an extremely poor prognosis. Currently, no biomarkers can accurately diagnose gallbladder cancer and predict patients' prognosis. XRCC1 is involved in tumorigenesis, progression, and chemo-resistance of several human cancers, but the role of XRCC1 in gallbladder cancer is never reported. In this study, we investigated the expression of XRCC1 and its clinicopathological and prognostic significance in gallbladder cancer, and explored the biological role of XRCC1 in gallbladder cancer cells. We found that XRCC1 was significantly up-regulated in gallbladder cancer in protein and mRNA levels. Positive XRCC1 expression was correlated with aggressive clinicopathological features and was an independent poor prognostic factor in gallbladder cancer. The ROC curves suggested that XRCC1 expression had potential clinicopathological diagnostic value in gallbladder cancer. In vitro, XRCC1 was overexpression in CD133⁺GBC-SD cells compared to GBC-SD cells. In functional experiment, XRCC1 knockdown had a non-significant impact on proliferation, migration, invasion, and apoptosis of CD133⁺GBC-SD cells. But, XRCC1 knockdown could significantly improve the sensitivity of CD133⁺GBC-SD cells to 5-Fluorouracil via promoting cell necrosis and apoptosis. Thus, this study indicates that XRCC1 may be a promising predictive biomarker of gallbladder cancer and a potential therapeutic target for gallbladder cancer.

DNA repair in cancer initiation, progression, and therapy-a double-edged sword

Genomic and mitochondrial DNA molecules are exposed continuously for a damaging activity of chemical, physical, and internal genotoxicants. When DNA repair machinery is not working efficiently, the generation of DNA lesions and mutations leads to carcinogenic transformation. The high number of mutation going up to 10⁵ per cell was recognized as a driving force of oncogenesis. Moreover, a high activity of DNA repair genes was hypothesized as a predisposition to metastasis. DNA repair potential has to be taken into account attempting to chemo- and/or radiotherapy. A low activity of DNA repair genes makes tumor cells more sensitive to therapy, but on the other hand, non-tumor cells getting lesions could form second primary cancer. Contrary, high activity of DNA repair genes counteracts attempted therapy. It means an individualized therapy based on recognition of DNA repair potential is recommended.