Persistent Increased Frequency of Genomic Instability in Women Diagnosed with Breast Cancer: Before, during, and after Treatments

Genetic variability of oxidative stress and DNA repair genes associated with pre-treatment cancer-related fatigue in women with breast cancer

PURPOSE

Investigate potential relationships between pre-treatment cancer-related fatigue (CRF) in women with early-stage breast cancer and variation in genes involved with oxidative stress and DNA repair.

METHODS

Investigated 39 functional and tagging single nucleotide polymorphisms (SNPs) in genes involved in oxidative stress (CAT, GPX1, SEPP1, SOD1, and SOD2) and DNA repair (ERCC2, ERCC3, ERCC5, and PARP1) in a sample (N = 219) that included n = 138 postmenopausal women diagnosed with early-stage breast cancer before initiation of therapy and n = 81 age- and education-matched healthy controls. Using the Profile of Mood States Fatigue/Inertia Subscale, fatigue occurrence and severity were evaluated in both groups. Regression analysis was used to independently identify significant SNPs for three outcomes: 1) any fatigue versus no fatigue, 2) clinically meaningful versus non-clinically meaningful fatigue, and 3) fatigue severity. Using a weighted multi-SNP method, genetic risk scores (GRS) were calculated for each participant, and GRS models were constructed for each outcome. Models were adjusted for age, pain, and symptoms of depression and anxiety.

RESULTS

SEPP1rs3877899, ERCC2rs238406, ERCC2rs238416, ERCC2rs3916874, and ERCC3rs2134794 were associated with fatigue occurrence and had a significant GRS model (OR = 1.317, 95%CI [1.067, 1.675], P ≤ 0.05). One SNP, SOD2rs5746136, was significant for clinically meaningful fatigue; therefore, a GRS model could not be constructed. ERCC3rs4150407, ERCC3rs4150477, and ERCC3rs2134794 were associated with fatigue severity with a significant GRS model (b = 1.010, 95%CI [1.647, 4.577], R² = 6.9%, P ≤ 0.01).

CONCLUSIONS

These results may contribute to identifying patients who are at risk of developing CRF. Oxidative stress and DNA repair biological pathways may be involved with CRF.

Recommendations and quality criteria for micronucleus studies with humans

Micronucleus (MN) analyses in peripheral blood lymphocytes and exfoliated cells from different organs (mouth, nose, bladder and cervix) are at present the most widely used approaches to detect damage of genetic material in humans. MN are extranuclear DNA-containing bodies, which can be identified microscopically. They reflect structural and numerical chromosomal aberrations and are formed as a consequence of exposure to occupational, environmental and lifestyle genotoxins. They are also induced as a consequence of inadequate intake of certain trace elements and vitamins. High MN rates are associated with increased risk of cancer and a range of non-cancer diseases in humans. Furthermore, evidence is accumulating that measurements of MN could be a useful tool for the diagnosis and prognosis of different forms of cancer and other diseases (inflammation, infections, metabolic disorders) and for the assessment of the therapeutic success of medical treatments. Recent reviews of the current state of knowledge suggest that many clinical studies have methodological shortcomings. This could lead to controversial findings and limits their usefulness in defining the impact of exposure concentrations of hazardous chemicals, for the judgment of remediation strategies, for the diagnosis of diseases and for the identification of protective or harmful dietary constituents. This article describes important quality criteria for human MN studies and contains recommendations for acceptable study designs. Important parameters that need more attention include sufficiently large group sizes, adequate duration of intervention studies, the exclusion of confounding factors which may affect the results (sex, age, body mass index, nutrition, etc.), the evaluation of appropriate cell numbers per sample according to established scoring criteria as well as the use of proper stains and adequate statistical analyses.

Obesity, oxidative DNA damage and vitamin D as predictors of genomic instability in children and adolescents

BACKGROUND/OBJECTIVES

Epidemiological evidence indicates obesity in childhood and adolescence to be an independent risk factor for cancer and premature mortality in adulthood. Pathological implications from excess adiposity may begin early in life. Obesity is concurrent with a state of chronic inflammation, a well-known aetiological factor for DNA damage. In addition, obesity has been associated with micro-nutritional deficiencies. Vitamin D has attracted attention for its anti-inflammatory properties and role in genomic integrity and stability. The aim of this study was to determine a novel approach for predicting genomic instability via the combined assessment of adiposity, DNA damage, systemic inflammation, and vitamin D status.

SUBJECTS/METHODS

We carried out a cross-sectional study with 132 participants, aged 10-18, recruited from schools and paediatric obesity clinics in London. Anthropometric assessments included BMI Z-score, waist and hip circumference, and body fat percentage via bioelectrical impedance. Inflammation and vitamin D levels in saliva were assessed by enzyme-linked immunosorbent assay. Oxidative DNA damage was determined via quantification of 8-hydroxy-2'-deoxyguanosine in urine. Exfoliated cells from the oral cavity were scored for genomic instability via the buccal cytome assay.

RESULTS

As expected, comparisons between participants with obesity and normal range BMI showed significant differences in anthropometric measures (p < 0.001). Significant differences were also observed in some measures of genomic instability (p < 0.001). When examining relationships between variables for all participants, markers of adiposity positively correlated with acquired oxidative DNA damage (p < 0.01) and genomic instability (p < 0.001), and negatively correlated with vitamin D (p < 0.01). Multiple regression analyses identified obesity (p < 0.001), vitamin D (p < 0.001), and oxidative DNA damage (p < 0.05) as the three significant predictors of genomic instability.

CONCLUSIONS

Obesity, oxidative DNA damage, and vitamin D deficiency are significant predictors of genomic instability. Non-invasive biomonitoring and predictive modelling of genomic instability in young patients with obesity may contribute to the prioritisation and severity of clinical intervention measures.

The radioprotective effect of N-acetylcysteine against x-radiation-induced renal injury in rats

The purpose of this study was therefore to investigate the effects of radiotherapy on the kidney and the potential use of agents such as N-acetylcysteine (NAC) in developing a future therapeutic protocol for radiation-induced nephrotoxicity at the histopathological and biochemical levels. Our study consisted of three groups: control (oral saline solution only; group 1), irradiation (IR; group 2), and NAC + IR (group 3). The irradiation groups received a single dose of whole-body 6-Gy x-irradiation. The NAC group received 300 mg/kg by the oral route for 7 days, from 5 days before irradiation to 2 days after. All subjects were sacrificed under anesthesia 2 days after irradiation. IR increased tubular necrosis scores (TNS), MDA, and caspase-3 expression, while reducing renal tissue GSH levels. We also observed dilation in renal corpuscles and tubules. Capillary congestion was present in the intertubular spaces. NAC reduced the levels of TNS, MDA, and caspase-3 expression, but increased the levels of renal tissue GSH. ROS-scavenging antioxidants may represent a promising means of preventing renal injury in patients undergoing radiotherapy.

Association of Elevated Peripheral Blood Micronucleus Frequency and Bmi-1 mRNA Expression with Metastasis in Iranian Breast Cancer Patients

Background:

In order to find cytogenetic and molecular metastasis biomarkers detectable in peripheral blood the spontaneous genomic instability expressed as micronuclei and Bmi-1 expression in peripheral blood of breast cancer (BC) patients were studied in different stages of the disease compared with unaffected first-degree relatives (FDRs) and normal control.

Methods:

The Cytokinesis Block Micronuclei Cytome (CBMN cyt) and nested real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) assays, were respectively used to measure genomic instability and Bmi-1 gene expression in 160 Iranian individuals comprised of BC patients in different stages of the disease, unaffected FDRs and normal control groups.

Result:

The frequency of micronuclei and Bmi-1 expression were dramatically higher in distant metastasis compared with non-metastatic BC. In spite of micronucleus frequency with no association with lymph node (LN) involvement and hormone receptor status, the Bmi-1 expression level was higher in LN positive and triple negative patients.

Conclusion:

Our results indicate that increased genomic instability expressed as micronuclei and higher Bmi-1 expression in peripheral blood are associated with metastasis in breast cancer. Therefore implementation of micronucleus assay and Bmi-1 expression analysis in blood as possible cytogenetic and molecular biomarkers in clinical level may potentially enhance the quality of management of patients with breast cancer.