Genetic Polymorphisms in the RAD51 Gene with a Risk of Head and Neck Cancer and Esophageal Cancer: A Meta-Analysis

Assessment of LINC-PINT genetic polymorphisms and esophageal squamous cell carcinoma risk in the Hainan Han population

OBJECTIVES

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor with high incidence and mortality rates worldwide. This study aimed to investigate the correlation between LINC-PINT polymorphisms and ESCC risk in the Hainan Han population.

METHODS

A total of 391 patients with ESCC and 452 healthy controls were enrolled to evaluate the effect of LINC-PINT SNPs (single nucleotide polymorphisms) on ESCC susceptibility. Associations were evaluated by calculating odds ratios (OR) and 95% confidence intervals (CIs). Multifactor dimensionality reduction analysis was performed to explore the association between SNP-SNP interactions and ESCC susceptibility. We further determined the correlation between clinical indicators and SNP in patients with ESCC.

RESULTS

Our study showed that rs157916 (OR 0.63, p = 0.011) and rs157928 (OR 0.80, p = 0.021) were associated with a decreased risk of ESCC. Stratified analysis indicated that rs157916 could decrease the risk of ESCC in people aged >64 years, in males, and non-drinkers (OR 0.58, p = 0.042; OR 0.58, p = 0.010; OR 0.62, p = 0.025, respectively). Rs16873842 was related to a decreased risk of ESCC in males (OR 0.70, p = 0.015). Rs7801029 was associated with ESCC risk in females (OR 0.39, p = 0.033) and non-drinkers (OR 0.68, p = 0.040). Rs7781295 decreased the ESCC risk in smokers (OR 0.58, p = 0.046) and drinkers (OR 0.58, p = 0.046). In addition, rs157928 played a protective role in ESCC risk in females (OR 0.39, p = 0.033) and non-smokers (OR 0.32, p = 0.006). Additionally, the best predictive model for ESCC was a combination of rs157916, rs16873842, rs7801029, rs7781295, rs28662387, and rs157928.

CONCLUSION

Our study revealed that LINC-PINT polymorphisms were associated with ESCC risk.

Single Nucleotide Polymorphisms in APE1, hOGG1, RAD51 Genes and their Association with Radiotherapy Induced Toxicity among Head and Neck Cancer Patients

BACKGROUND

Radiotherapy (RT) is a crucial treatment for head and neck cancer however, it causes adverse reactions to the normal tissue and organs adjacent to target tumor. The present study was carried out to investigate possible association of single nucleotide polymorphism in DNA repair genes with toxicity effects of radiotherapy on normal tissue.

METHODS

Three hundred and fifty head and neck cancer patients receiving radiotherapy treatment were enrolled in this study. The adverse after effects of radiotherapy on the normal tissue in the form of skin reactions were recorded. Single nucleotide polymorphisms of APE1 (rs1130409), hOGG1 (rs1052133) and Rad51 (rs1801320, rs1801321) genes were studied by polymerase chain reaction-Restriction fragment length polymorphism (PCR-RFLP) and direct DNA sequencing methods and their association with development of severe radio-toxicity effects was evaluated logistic regression analysis.

RESULTS

The 172G/T polymorphism of Rad51 was 2.85 times higher and significantly associated with skin reactions (OR=2.85, 95% CI: 1.50-5.41; p=0.001) and severe oral mucositis (OR=4.96, 95% CI: 2.40-10.25; p<0.0001). These results suggested that the polymorphic nature of Rad51 is responsible for risk of radiotherapy adverse effects in HNC patients. The variant 326Cys and heterozygous 326Ser/Cys genotype of hOGG1 was significantly associated with high tumor grade (OR=3.16 95% CI: 1.66-5.99; p=0.0004, and OR=3.97 95% CI: 2.15-7.34; p=<0.0001 respectively). The homozygous variant 172TT genotype of Rad51 showed positive association with poor response of both tumor and nodes towards radiotherapy treatment (p=0.007 and p=0.022).

CONCLUSIONS

Interpretation of our results revealed significant association of rs1801321 SNP of Rad51 with development of adverse toxicity reactions in normal tissue of head and neck cancer patients treated with radiotherapy.

New RAD51 Inhibitors to Target Homologous Recombination in Human Cells

Targeting DNA repair proteins with small-molecule inhibitors became a proven anti-cancer strategy. Previously, we identified an inhibitor of a major protein of homologous recombination (HR) RAD51, named B02. B02 inhibited HR in human cells and sensitized them to chemotherapeutic drugs in vitro and in vivo. Here, using a medicinal chemistry approach, we aimed to improve the potency of B02. We identified the B02 analog, B02-isomer, which inhibits HR in human cells with significantly higher efficiency. We also show that B02-iso sensitizes triple-negative breast cancer MDA-MB-231 cells to the PARP inhibitor (PARPi) olaparib.

Genetic Variants of DNA Repair Genes as Predictors of Radiation-Induced Subcutaneous Fibrosis in Oropharyngeal Carcinoma

Purpose

To investigate the impact of genetic variants of DNA repair and pro-fibrotic pathway genes on the severity of radiation-induced subcutaneous fibrosis in patients of oropharyngeal carcinoma treated with radical radiotherapy.

Materials and Methods

Patients of newly diagnosed squamous cell carcinoma of oropharynx being treated with two-dimensional radical radiotherapy were enrolled in the study. Patients who had undergone surgery or were receiving concurrent chemotherapy were excluded. Patients were followed up at 6 weeks post completion of radiotherapy and every 3 months thereafter for a median of 16 months. Subcutaneous fibrosis was graded according to the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC) grading system and the maximum grade was recorded over the length of the patient’s follow-up. Patients with severe fibrosis (≥G3), were compared to patients with minor (≤G2) fibrotic reactions. Eight single nucleotide polymorphisms of 7 DNA repair genes and 2 polymorphisms of a single pro-fibrotic pathway gene were analyzed by Polymerase Chain Reaction and Restriction Fragment Length Polymorphism and were correlated with the severity of subcutaneous fibrosis.

Results

179 patients were included in the analysis. Subcutaneous fibrosis was seen in 168 (93.9%) patients. 36 (20.1%) patients had severe (grade 3) fibrosis. On multivariate logistic regression analysis, Homozygous CC genotype of XRCC3 (722C>T, rs861539) (p=0.013*, OR 2.350, 95% CI 1.089-5.382), Homozygous AA genotype of ERCC4 Ex8 (1244G>A, rs1800067) (p=0.001**, OR 11.626, 95% CI 2.490-275.901) and Homozygous TT genotype of XRCC5 (1401G>T, rs828907) (p=0.020*, OR 2.188, 95% CI 1.652-7.334) were found to be predictive of severe subcutaneous fibrosis. On haplotype analysis, the cumulative risk of developing severe fibrosis was observed in patients carrying both haplotypes of variant Homozygous AA genotype of ERCC4 Ex8 (1244G>A, rs1800067) and Homozygous TT genotype of XRCC5 (1401 G>T, rs828907) (p=0.010*, OR 26.340, 95% CI 4.014-76.568).

Conclusion

We demonstrated significant associations between single nucleotide polymorphisms of DNA repair genes and radiation-induced subcutaneous fibrosis in patients of oropharyngeal carcinoma treated with radiotherapy. We propose to incorporate these genetic markers into predictive models for identifying patients genetically predisposed to the development of radiation-induced fibrosis, thus guiding personalized treatment protocols.

Transcriptome profiling reveals the molecular processes for survival of Lysinibacillus fusiformis strain 15-4 in petroleum environments

A bacterial strain designated Lysinibacillus fusiformis 15-4 was isolated from oil-free soil on the Qinghai-Tibet Plateau, which can grow well utilizing petroleum hydrocarbons as a carbon source at a lower temperature. To deeply characterize the molecular adaptations and metabolic processes of this strain when grown in a petroleum-containing environment, transcriptome analysis was performed. A total of 4664 genes and the expression of 3969 genes were observed in strain 15-4. When the strain was grown in petroleum-containing medium, 2192 genes were significantly regulated, of which 1312 (60%) were upregulated and 880 (40%) were downregulated. This strain degraded and adapted to petroleum via modulation of diverse molecular processes, including improvements in transporter activity, oxidoreductase/dehydrogenase activity, two-component system/signal transduction, transcriptional regulation, fatty acid catabolism, amino acid metabolism, and environmental stress responses. Many strain-specific genes were involved in the oxidation of hydrocarbon compounds, such as several luciferase family alkane monooxygenase genes, flavin-utilizing monooxygenase family genes, and flavoprotein-like family alkanesulfonate monooxygenase genes. Several cold shock protein genes were also induced suggesting adaptation to cold environments and the potential for petroleum degradation at low temperatures. The results obtained in this study may broaden our understanding of molecular adaptation of bacteria to hydrocarbon-containing environments and may provide valuable data for further study of L. fusiformis.