The role of XRCC4 in carcinogenesis and anticancer drug discovery

Systematic analysis identifies XRCC4 as a potential immunological and prognostic biomarker associated with pan-cancer

BACKGROUND

XRCC4 is a NHEJ factor identified recently that plays a vital role in repairing DNA double-stranded breaks. Studies have reported the associations between abnormal expression of XRCC4 and tumor susceptibility and radiosensitivity, but the potential biological mechanisms by which XRCC4 exerts effects on tumorigenesis are not fully understood. This study aimed to systematically investigate the role of XRCC4 across cancer types.

METHODS

The TIMER, GTEX and Xiantao Academic database were used to interpret the expression of XRCC4. Genomic alterations and protein expression in human organic and tumor tissues were applied in cBioPortal and the Human Protein Atlas databases. Correlations between XRCC4 expression and immune and molecular subtypes were analyzed by using the TISIDB database. Protein-protein interactions, GO and KEGG enrichment were also applied for XRCC4-related genes. The TIMER and the Tumor Immune Single Cell Hub (TISCH) online databases were used to explore the relationship between XRCC4 and tumor immune microenvironment. Drug sensitivity information was acquired from the CellMiner database to analyze the effect of XRCC4 on sensitivity analysis.

RESULTS

The XRCC4 expression was significantly upregulated in 15 tumor types and downregulated in two tumor types compared with the normal tissues, most of which were validated by the results of Xiantao academic platform. XRCC4 was expressed at intermediate level in malignant cells. The XRCC4 expression was related to the molecular and immune subtypes of human cancers, and the survival outcome of 11 types of cancers, including KIRC, STAD and LIHC. The main type of frequent genetic alteration is amplification. Strong correlations were also found between XRCC4 and immune checkpoint genes in 33 human cancers. Furthermore, the abnormal expression of XRCC4 was related to immune cell infiltration and drug sensitivity. Enrichment analysis showed that XRCC4 was significantly correlated with DNA damage response.

CONCLUSIONS

This comprehensive pan-cancer analysis suggested that XRCC4 may play a vital role in the prognosis and immunotherapy response in cancer patients, and it is a promising therapy target in the future.

The Venom of Philippine Tarantula (Theraphosidae) Contains Peptides with Pro-Oxidative and Nitrosative-Dependent Cytotoxic Activities against Breast Cancer Cells (MCF-7) In Vitro

Background:

Breast cancer is a multifactorial disease that affects women worldwide. Its progression is likely to be executed by oxidative stress wherein elevated levels of reactive oxygen and nitrogen species drive several breast cancer pathologies. Spider venom contains various pharmacological peptides which exhibit selective activity to abnormal expression of ion channels on cancer cell surface which can confer potent anti-cancer activities against this disease.

Methods:

Venom was extracted from a Philippine tarantula by electrostimulation and fractionated by reverse phase-high performance liquid chromatography (RP-HPLC). Venom fractions were collected and used for in vitro analyses such as cellular toxicity, morphological assessment, and oxidative stress levels.

Results:

The fractionation of crude spider venom generated several peaks which were predominantly detected spectrophotometrically and colorimetrically as peptides. Treatment of MCF-7 cell line of selected spider venom peptides induced production of several endogenous radicals such as hydroxyl radicals (•OH), nitric oxide radicals (•NO), superoxide anion radicals (•O²⁻) and lipid peroxides via malondialdehyde (MDA) reaction, which is comparable with the scavenging effects afforded by 400 µg/mL vitamin E and L-cysteine (p<0.05). Concomitantly, the free radicals produced decrease the mitochondrial membrane potential and metabolic activity as detected by rhodamine 123 and tetrazolium dye respectively (p>0.05). This is manifested by cytotoxicity in MCF-7 cells as seen by increase in membrane blebbing, cellular detachment, caspase activity and nuclear fragmentation.

Conclusion:

These data suggest that the Philippine tarantula venom contains peptide constituents exhibiting pro-oxidative and nitrosative-dependent cytotoxic activities against MCF-7 cells and can indicate mechanistic insights to further explore its potential application as prooxidants in cancer therapy.

XRCC4 c.1394G>T Single Nucleotide Polymorphisms and Breast Cancer Risk among Filipinos

Background:

The identification of cancer-associated single nucleotide polymorphisms (SNP) and mutation genes is a promising approach in recognizing individuals who are at risk of developing cancer. Hence, this study was conducted to determine the association between XRCC4 c.1394G>T SNP and breast cancer development among Filipinos.

Methods:

Genotyping for XRCC4 c.1394G>T SNP was performed on breast cancer patients (n=103) and their age- and sex- matched clinically healthy controls (n=103) by polymerase chain reaction – restriction fragment length polymorphism.

Results:

Significant difference in genotype (p=0.007) and allele (p=0.003) frequencies in XRCC4 c.1394G>T was observed between the breast cancer cases and controls. Carriers of the XRCC4 c.1394 G>T genotype were observed to have significantly higher risk of developing breast cancer compared to individuals with T/T genotype (OR=2.67, 95% CI: 1.36 – 5.25). XRCC4 c.1394G>T combined with passive smoking may also significantly increase risk of breast cancer (OR=14.73; 95% CI= 9.88-18.86).

Conclusion:

XRCC4 c. 1394G>T may be associated with breast cancer development among Filipinos.

Prognostic significance of XRCC4 expression in hepatocellular carcinoma

Background

Our previous investigations have shown that the variants of X-ray repair complementing 4 (XRCC4) may be involved in hepatocellular carcinoma (hepatocarcinoma) tumorigenesis. This study aimed to investigate the possible prognostic significance of XRCC4 expression for hepatocarcinoma patients and possible value for the selection of transarterial chemoembolization (TACE) treatment.

Materials and Methods

We conducted a hospital-based retrospective analysis (including 421 hepatocarcinoma cases) to analyze the effects of XRCC4 on hepatocarcinoma prognosis and TACE. The levels of XRCC4 expression were tested using immunohistochemistry. The sensitivity of cancer cells to anti-cancer drug doxorubicin was evaluated using the half-maximal inhibitory concentration (IC50).

Results

XRCC4 expression was significantly correlated with pathological features including tumor stage, liver cirrhosis, and micro-vessel density. XRCC4 expression was an independent prognostic factor of hepatocarcinoma, and TACE treatments had no effects on prognosis of hepatocarcinoma patients with high XRCC4 expression. More intriguingly, TACE improved the prognosis of hepatocarcinoma patients with low XRCC4 expression. Functionally, XRCC4 overexpression increased while XRCC4 knockdown reduced the IC50 of cancer cells to doxorubicin.

Conclusions

These results suggest that XRCC4 may be an independent prognostic factor for hepatocarcinoma patients, and that decreasing XRCC4 expression may be beneficial for post-operative adjuvant TACE treatment in hepatocarcinoma.

DNA repair gene XRCC4 codon 247 polymorphism modified diffusely infiltrating astrocytoma risk and prognosis

The DNA repair gene X-ray cross-complementary group 4 (XRCC4), an important caretaker of the overall genome stability, is thought to play a major role in human tumorigenesis. We investigated the association between an important polymorphic variant of this gene at codon 247 (rs373409) and diffusely infiltrating astrocytoma (DIA) risk and prognosis. This hospital-based case-control study investigated this association in the Guangxi population. In total, 242 cases with DIA and 358 age-, sex-, and race-matched healthy controls were genotyped using TaqMan-PCR technique. We found a significant difference in the frequency of XRCC4 genotypes between cases and controls. Compared with the homozygote of XRCC4 codon 247 Ala alleles (XRCC4-AA), the genotypes of XRCC4 codon 247 Ser alleles (namely XRCC4-AS or -SS) increased DIA risk (odds ratios [OR], 1.82 and 2.89, respectively). Furthermore, XRCC4 polymorphism was correlated with tumor dedifferentiation of DIA (r = 0.261, p < 0.01). Additionally, this polymorphism modified the overall survival of DIA patients (the median survival times were 26, 14, and 8 months for patients with XRCC4-AA, -AS, and -SS, respectively). Like tumor grade, XRCC4 codon 247 polymorphism was an independent prognostic factor influencing the survival of DIA. These results suggest that XRCC4 codon 247 polymorphism may be associated with DIA risk and prognosis among the Guangxi population.

Genetic polymorphisms in DNA repair genes XRCC4 and XRCC5 and aflatoxin B1-related hepatocellular carcinoma

BACKGROUND

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity and may play an important role in carcinogenesis. We investigated the role of genetic polymorphisms at XRCC4 codon 247 (rs3734091, XRCC4P) and XRCC5 codon 180 (rs80309960, XRCC5P) in liver cancer (hepatocellular carcinoma) caused by aflatoxin B1 (AFB1).

METHODS

A hospital-based case-control study, including 1499 liver cancer cases and 2045 controls without any liver disease, was conducted in a high aflatoxin exposure area in the Guangxi region of China to assess the relationship between these two polymorphisms and aflatoxin-related liver cancer risk and prognosis. Genotypes, mRNA levels, and the hot-spot mutation of TP53 gene (TP53M) related to AFB1 exposure was tested using TaqMan-PCR technique. XRCC4 protein level was analyzed by immunohistochemistry.

RESULTS

For XRCC4P and XRCC5P, only XRCC4P modified liver cancer risk. Compared with the homozygote of XRCC4 codon 247 Ala alleles (XRCC4-AA), the genotypes of XRCC4 codon 247 Ser alleles (namely XRCC4-AS or -SS) increased liver cancer risk (odds ratio [OR] = 1.35 and 2.02, respectively). Significant interactive effects between risk genotypes (OR > 1) and aflatoxin exposure status were also observed in the joint effects analysis. Moreover, this polymorphism was associated not only with lower XRCC4 expression levels but also with higher AFB1-DNA adduct levels and increasing TP53M and portal vein tumor risk. Additionally, XRCC4P modified the recurrence-free survival and overall survival of cases, especially under conditions of high aflatoxin exposure.

CONCLUSION

XRCC4P may be a genetic modifier for the risk and outcome of hepatocellular carcinoma induced by AFB1 exposure.

Polymorphisms in the coding region of X-ray repair complementing group 4 and aflatoxin B1-related hepatocellular carcinoma

X-ray repair complementing group 4 (XRCC4) is very important in maintaining overall genome stability and may play an important role in carcinogenesis. We aimed to investigate the role of polymorphisms in the coding region of this gene in hepatocellular carcinoma (HCC) caused by aflatoxin B1 (AFB1). A hospital-based case-control study, including 1,499 HCC cases and 2,045 controls without any liver diseases or tumors, was conducted in a high AFB1 exposure area (the Guangxi region) to assess the relationship between 21 polymorphisms in the coding region of XRCC4 and AFB1-related HCC risk and prognosis. Among these 21 polymorphisms, only rs28383151 modified HCC risk. These individuals with the genotypes of rs28383151 A alleles (rs28383151-GA/AA), compared with the homozygote of rs28383151 G alleles (rs28383151-GG), faced increasing risk of HCC (odds ratio [OR]: 2.17; 95% confidence interval: 1.77-2.67). Significant interactive effects between risk genotypes (OR, >1) and AFB1 exposure status were also observed in the joint-effects analysis. Furthermore, this polymorphism was correlated not only with lower XRCC4-expressing levels, but also with higher AFB1-DNA adducts levels and increasing TP53M and portal vein tumor risk. The rs28383151 polymorphism modified the recurrence-free survival and overall survival of HCC patients, especially under high AFB1 exposure conditions. Additionally, this polymorphism multiplicatively interacted with the glutathione S-transferase M1 polymorphism with respect to HCC risk (ORinteraction = 2.13).

CONCLUSION

Genetic polymorphisms in the coding region of XRCC4 may be risk and prognostic biomarkers of AFB1-related HCC, and rs28383151 is such a potential candidate.

Predictive role of XRCC5/XRCC6 genotypes in digestive system cancers

Cancers are a worldwide concern; oral, esophageal and gastrointestinal cancers represent important causes of cancer-related mortality and contribute to a significant burden of human health. The DNA repair systems are the genome caretakers, playing a critical role in the initiation and progression of cancers. However, the association between the genomic variations of DNA repair genes and cancer susceptibility is not well understood. This review focuses on the polymorphic genotypes of the non-homologous end-joining DNA repair system, highlighting the role of two genes of this pathway, XRCC5 and XRCC6, in the susceptibility to digestive system cancers and discussing their potential contributions to personalized medicine.

Role of the XRCC5/XRCC6 dimer in carcinogenesis and pharmacogenomics

Over the past few decades, the incidence of cancer has rapidly increased all over the world and cancer remains a major threat to public health. It is believed that cancer results from a series of genetic alterations that lead to the progressive disorder of the normal mechanisms controlling cell proliferation, differentiation, death and/or genomic stability. The response of the cell to genetic injury and its ability to maintain genomic stability by means of a variety of DNA repair mechanisms are therefore essential in preventing tumor initiation and progression. From the same viewpoint, the relative role of DNA repair as a biomarker for prognosis, predictor of drug and therapy responses or indeed as a target for novel gene therapy, is very promising. In this article, we have summarized the studies investigating the association between the XRCC5/XRCC6 dimer and the susceptibility to multiple cancers and discuss its role in carcinogenesis and its potential application to anticancer drug discovery.

Genetic polymorphisms in DNA repair genes XPC, XPD, and XRCC4, and susceptibility to Helicobacter pylori infection-related gastric antrum adenocarcinoma in Guangxi population, China

Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of gastric antrum adenocarcinoma (GAA) related to Helicobacter pylori infection. This study, including 361 GAAs and 616 controls without any evidence of tumors, was designed to evaluate the association between the polymorphisms of DNA repair genes XPC Ala499Val (RS#2228000) and Lys939Gln (RS#2228001), XPD Lys751Gln (RS#13181), and XRCC4 Ala247Ser (RS#3734091) and Ser298Asn (RS#1805377), and GAA risk for Guangxi population by means of TaqMan-PCR analysis. Increased risks of GAA were found for individuals with H. pylori positive [odds ratio (OR), 2.48; 95% confidence interval (CI), 1.84-3.33] or cagA positive (OR, 7.34; 95% CI, 5.46-9.87). No differences were observed among the studied groups with regard to the genotype distribution of XPC codons 499 and 939 and of XRCC4 codon 247; but XPD codon 751 genotypes with Gln [ORs (95% CI) were 2.67 (1.98-3.58) and 3.97 (2.64-5.99) for Lys/Gln and Gln/Gln, respectively] and XRCC4 codon 298 genotypes with Asn [ORs (95% CI) were 3.01 (2.21-4.10) and 4.78 (3.24-7.05) for Ser/Asn and Asn/Asn, respectively] increased the risk of GAA. Interestingly, there was an interactive effect between the risk genotypes of these two genes and cagA-positive status in the GAA risk (OR(interact) = 2.05 and 2.08, respectively). However, we did not find the gene-H. pylori-status interaction effects on the risk of GAA (P(interact) > 0.05). The results suggested that the polymorphisms of XPD codon 751 and XRCC4 codon 298 are associated with an increased risk of developing H. pylori-related GAA among Guangxi population.

Interaction of Exo1 genotypes and smoking habit in oral cancer in Taiwan

Exonuclease 1 (Exo1) is an important nuclease involved in the mismatch repair system that helps to maintain genomic stability, to modulate DNA recombination, and to mediate cell cycle arrest. Potential polymorphisms in Exo1 may alter cancer risks by influencing the repair activity of Exo1. Therefore, we hypothesized that single-nucleotide polymorphisms in Exo1 were associated with the risk of oral cancer. In this hospital-based study, the associations of Exo1 A-1419G (rs3754093), C-908G (rs10802996), A238G (rs1776177), C498T (rs1635517), K589E (rs1047840), G670E (rs1776148), C723R (rs1635498), L757P (rs9350) and C3114T (rs851797) polymorphisms with oral cancer risk in a central Taiwan population were investigated. In total, 680 patients with oral cancer and 680 age- and gender-matched healthy controls recruited from the China Medical University Hospital were genotyped. A significantly different distribution is found in the frequency of the Exo1 K589E genotype, but not the other genotypes, between the oral cancer and control groups. The A allele Exo1 K589E conferred a significant (P=6.18E-8) increased risk of oral cancer. Gene-environment interactions with smoking were significant for Exo1 K589E polymorphism (OR=2.509, 95% CI=1.914-3.287). Our results provide evidence that the A allele of the Exo1 K589E may be associated with the development of oral cancer.