Association of XRCC1 polymorphisms with thyroid cancer risk

Polymorphisms of DNA Repair Genes in Thyroid Cancer

The incidence of thyroid cancer, one of the most common forms of endocrine cancer, is increasing rapidly worldwide in developed and developing countries. Various risk factors can increase susceptibility to thyroid cancer, but particular emphasis is put on the role of DNA repair genes, which have a significant impact on genome stability. Polymorphisms of these genes can increase the risk of developing thyroid cancer by affecting their function. In this article, we present a concise review on the most common polymorphisms of selected DNA repair genes that may influence the risk of thyroid cancer. We point out significant differences in the frequency of these polymorphisms between various populations and their potential relationship with susceptibility to the disease. A more complete understanding of these differences may lead to the development of effective prevention strategies and targeted therapies for thyroid cancer. Simultaneously, there is a need for further research on the role of polymorphisms of previously uninvestigated DNA repair genes in the context of thyroid cancer, which may contribute to filling the knowledge gaps on this subject.

A High-Quality Blue Whale Genome, Segmental Duplications, and Historical Demography

The blue whale, Balaenoptera musculus, is the largest animal known to have ever existed, making it an important case study in longevity and resistance to cancer. To further this and other blue whale-related research, we report a reference-quality, long-read-based genome assembly of this fascinating species. We assembled the genome from PacBio long reads and utilized Illumina/10×, optical maps, and Hi-C data for scaffolding, polishing, and manual curation. We also provided long read RNA-seq data to facilitate the annotation of the assembly by NCBI and Ensembl. Additionally, we annotated both haplotypes using TOGA and measured the genome size by flow cytometry. We then compared the blue whale genome with other cetaceans and artiodactyls, including vaquita (Phocoena sinus), the world's smallest cetacean, to investigate blue whale's unique biological traits. We found a dramatic amplification of several genes in the blue whale genome resulting from a recent burst in segmental duplications, though the possible connection between this amplification and giant body size requires further study. We also discovered sites in the insulin-like growth factor-1 gene correlated with body size in cetaceans. Finally, using our assembly to examine the heterozygosity and historical demography of Pacific and Atlantic blue whale populations, we found that the genomes of both populations are highly heterozygous and that their genetic isolation dates to the last interglacial period. Taken together, these results indicate how a high-quality, annotated blue whale genome will serve as an important resource for biology, evolution, and conservation research.

Identification of crucial genes involved in thyroid cancer development

BACKGROUND

A malignancy of the endocrine system, one of the most common types, is thyroid cancer. It is proven that children who receive radiation treatment for leukemia or lymphoma are at a heightened risk of thyroid cancer due to low-dose radiation exposure throughout childhood. Several factors can increase the risk of thyroid cancer (ThyCa), such as chromosomal and genetic mutations, iodine intake, TSH levels, autoimmune thyroid disorders, estrogen, obesity, lifestyle changes, and environmental contaminants.

OBJECTIVES

The study aimed to identify a specific gene as an essential candidate for thyroid cancer progression. We might be able to focus on developing a better understanding of how thyroid cancer is inherited.

METHODS

The review article uses electronic databases such as PubMed, Google Scholar, Ovid MEDLINE, Embase, and Cochrane Central. The most frequently associated genes with thyroid cancer found on PubMed were BAX, XRCC1, XRCC3, XPO5, IL-10, BRAF, RET, and K-RAS. To perform an electronic literature search, genes derived from DisGeNET: a database of gene-disease associations, including PRKAR1A, BRAF, RET, NRAS, and KRAS, are used.

CONCLUSION

Examining the genetics of thyroid cancer explicitly emphasizes the primary genes associated with the pathophysiology of young and older people with thyroid cancer. Developing such gene investigations at the beginning of the thyroid cancer development process can identify better outcomes and the most aggressive thyroid cancers.

GA Genotype of the Arg280His Polymorphism on The XRCC1 Gene: Genetic Susceptibility Genotype in Differentiated Thyroid Carcinomas?

Differentiated thyroid carcinomas (DTC) are the most common form of endocrine malignancies. The role of genetic variations in the development of papillary thyroid carcinoma (PTC) is approximately 60.0-70.0%. The X-ray repair cross-complementing group 1 (XRCC1) protein has an important role in DNA repair mechanisms and genomic polymorphisms of XRCC1 gene affect the function of the protein. In the present case-control study, we aimed to compare the genotype frequency distributions of XRCC1 single nucleotide polymorphisms (SNPs) in terms of the presence of other risk factors (Hashimoto’s thyroiditis, smoking, obesity, radiation exposure) in patients with thyroid nodules who had fine-needle aspiration biopsy (FNAB) and/or thyroid surgery due to thyroid cancer. The genotype frequency distributions of three common XRCC1 SNPs (Arg194Trp, Arg399Gln, Arg280His) were compared to those with DTC (n = 228), benign thyroid nodules (BTN, n = 100) and healthy controls (n = 93) in terms of certain pre defined risk factors such as the presence of Hashimoto’s thyroiditis, smoking, obesity, a family history of thyroid cancer and radiation exposure. The frequency of the GA genotype of Arg280His in DTC cases was found to be higher than in those with BTN and the healthy control group (p <0.001). The DTC group had the lowest frequency of AA genotype of Arg280His (35.5%, p <0.001). Among those with a family history of thyroid cancer, 78.9% had a GA genotype and 21.1% had the AA genotype of Arg280His (p = 0.004). The Arg280His GA genotype was more common in DTC than in cancer-free controls. The GA genotype frequency was also high in DTC cases with a family history of thyroid cancer.

Relationship between expression of XRCC1 and tumor proliferation, migration, invasion, and angiogenesis in glioma

Recently, XRCC1 polymorphisms were reported to be associated with glioma in Chinese population. However, only a few studies reported on the XRCC1 expression, and cancer progression. In this study, we investigated whether XRCC1 plays a role in glioma pathogenesis. Using the tissue microarray technology, we found that XRCC1 expression is significantly decreased in glioma compared with tumor adjacent normal brain tissue (P < 0.01, χ² test) and reduced XRCC1 staining was associated with WHO stages (P < 0.05, χ² test). The mRNA and protein levels of XRCC1 were significantly downregulated in human primary glioma tissues (P < 0.001, χ² test). We also found that XRCC1 was significantly decreased in glioma cell lines compared to normal human astrocytes (P < 0.01, χ² test). Overexpression of XRCC1 dramatically reduced the proliferation and caused cessation of cell cycle. The reduced cell proliferation is due to G1 phase arrest as cyclin D1 is diminished whereas p16 is upregulated. We further demonstrated that XRCC1 overexpression suppressed the glioma cell migration and invasion abilities by targeting MMP-2. In addition, we also found that overexpression of XRCC1 sharply inhibited angiogenesis, which correlated with down-regulation of VEGF. The data indicate that XRCC1 may be a tumor suppressor involved in the progression of glioma.

Genetic Association of XRCC1 Gene rs1799782, rs25487 and rs25489 Polymorphisms with Risk of Thyroid Cancer: a Systematic Review and Meta-Analysis

Background:

A number of case-control studies have evaluated associations between the X-ray cross complementary group 1 protein (XRCC1) gene rs1799782 (Arg194Trp), rs25487 (Arg399Gln) and rs25489 (Arg280His) polymorphisms and thyroid cancer (TC) risk, but the results remain inconclusive.

Materials and Methods:

A systematic literature search was performed using PubMed and Google Scholar Search. According to defined criteria data were extracted and pooled odds ratios with 95% confidence intervals were calculated under five genetic models.

Results:

A total of 8 studies with 1,672 cases and 2,805 controls for the rs1799782 polymorphism, 14 studies with 2,506 cases and 5,180 controls for the rs25487 polymorphism, and 11 studies with 2,197 cases and 4,761 controls for the rs25489 polymorphism were included in this meta-analysis. Overall, there was a statistical association between XRCC1 rs1799782 polymorphism and TC risk with the homozygote genetic model (TT vs. CC: OR = 1.815, 95% CI = 1.115-2.953, p= 0.016) and the recessive genetic model (TT vs. TC+ CC: OR = 1.854, 95% CI = 1.433-2.399, p= <0.001). In the subgroup analysis by ethnicity, significantly increased TC risk was observed only in Asians under the recessive model (TT vs. TC+ CC: OR = 1.816, 95% CI = 1.398-2.358, p= <0.001). In addition, there was no positive association between XRCC1 rs25487 and rs25489 polymorphisms and risk of TC. However, there was a significant association between XRCC1 rs25487 polymorphism risk of TC among Caucasians with allele genetic comparison (A vs. G: OR= 0.882, 95% CI = 0.794-0.979, p= 0.136) and dominant genetic comparison (AA+AG vs. GG: OR=0.838, 95% CI = 0.728-0.965, p= 0.014).

Conclusions:

The results of our meta-analysis suggest an increased risk of TC with the XRCC1 rs1799782 and rs25487 polymorphisms. However, the XRCC1 rs25489 polymorphism appeared to be without influence.

NADPH oxidases: new actors in thyroid cancer?

Hydrogen peroxide (H2O2) is a crucial substrate for thyroid peroxidase, a key enzyme involved in thyroid hormone synthesis. However, as a potent oxidant, H2O2 might also be responsible for the high level of oxidative DNA damage observed in thyroid tissues, such as DNA base lesions and strand breakages, which promote chromosomal instability and contribute to the development of tumours. Although the role of H2O2 in thyroid hormone synthesis is well established, its precise mechanisms of action in pathological processes are still under investigation. The NADPH oxidase/dual oxidase family are the only oxidoreductases whose primary function is to produce reactive oxygen species. As such, the function and expression of these enzymes are tightly regulated. Thyrocytes express dual oxidase 2, which produces most of the H2O2 for thyroid hormone synthesis. Thyrocytes also express dual oxidase 1 and NADPH oxidase 4, but the roles of these enzymes are still unknown. Here, we review the structure, expression, localization and function of these enzymes. We focus on their potential role in thyroid cancer, which is characterized by increased expression of these enzymes.

Association between the XRCC1 polymorphisms and thyroid cancer risk: a meta-analysis from case-control studies

Background

The previous published data on the association between the X-ray repair cross-conplementation group 1 (XRCC1) polymorphisms and thyroid cancer risk remained controversial. Hence, we performed a meta-analysis on all available studies that provided 1729 cases and 3774 controls (from 11 studies) for XRCC1 Arg399Gln, 1040 cases and 2487 controls for Arg194Trp (from 7 studies), and 1432 cases and 3356 controls for Arg280His (from 8 studies).

Methodology/Principal Findings

PubMed, CNKI, and EMBASE database were searched to identify relevant studies. Overall, no significant association was found between XRCC1 Arg399Gln (recessive model: OR = 0.95, 95% CI = 0.77–1.15; dominant model: OR = 0.89, 95% CI = 0.75–1.05; homozygote model: OR = 0.92, 95% CI = 0.69–1.23; Heterozygote model: OR = 0.91, 95% CI = 0.80–1.03; additive model: OR = 0.93, 95% CI = 0.81–1.07), Arg194Trp (recessive model: OR = 1.41, 95% CI = 0.62–3.23; dominant model: OR = 1.01, 95% CI = 0.77–1.34; homozygote model: OR = 1.42, 95% CI = 0.55–3.67; Heterozygote model: OR = 1.03, 95% CI = 0.85–1.26; additive model: OR = 1.08, 95% CI = 0.81–1.42), and Arg280His (recessive model: OR = 1.08, 95% CI = 0.56–2.10; dominant model: OR = 1.01, 95% CI = 0.84–1.22; homozygote model: OR = 1.00, 95% CI = 0.51–1.96; Heterozygote model: OR = 1.04, 95% CI = 0.75–1.42; additive model: OR = 1.03, 95% CI = 0.86–1.23) and thyroid cancer risk when all the eligible studies were pooled into the meta-analysis. In the further stratified and sensitivity analyses, significant association was still not found in these three genetic polymorphisms.

Conclusions/Significance

In summary, this meta-analysis indicates that XRCC1 Arg399Gln, Arg280His, and Arg194Trp are not associated with thyroid cancer.