Folate Repletion after Deficiency Induces Irreversible Genomic and Transcriptional Changes in Human Papillomavirus Type 16 (HPV16)-Immortalized Human Keratinocytes.

Supplementation of micronutrients like folate is a double-edged sword in terms of their ambivalent role in cell metabolism. Although several epidemiological studies support a protective role of folate in carcinogenesis, there are also data arguing for an opposite effect. To address this issue in the context of human papillomavirus (HPV)-induced transformation, the molecular events of different folate availability on human keratinocytes immortalized by HPV16 E6 and E7 oncoproteins were examined. Several sublines were established: Control (4.5 µM folate), folate deficient (0.002 µM folate), and repleted cells (4.5 µM folate). Cells were analyzed in terms of oncogene expression, DNA damage and repair, karyotype changes, whole-genome sequencing, and transcriptomics. Here we show that folate depletion irreversibly induces DNA damage, impairment of DNA repair fidelity, and unique chromosomal alterations. Repleted cells additionally underwent growth advantage and enhanced clonogenicity, while the above mentioned impaired molecular properties became even more pronounced. Overall, it appears that a period of folate deficiency followed by repletion can shape immortalized cells toward an anomalous phenotype, thereby potentially contributing to carcinogenesis. These observations should elicit questions and inquiries for broader additional studies regarding folate fortification programs, especially in developing countries with micronutrient deficiencies and high HPV prevalence.

PARP1 inhibition alleviates injury in ARH3-deficient mice and human cells.

Poly(ADP-ribosyl)ation refers to the covalent attachment of ADP-ribose to protein, generating branched, long chains of ADP-ribose moieties, known as poly(ADP-ribose) (PAR). Poly(ADP-ribose) polymerase 1 (PARP1) is the main polymerase and acceptor of PAR in response to DNA damage. Excessive intracellular PAR accumulation due to PARP1 activation leads cell death in a pathway known as parthanatos. PAR degradation is mainly controlled by poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribose-acceptor hydrolase 3 (ARH3). Our previous results demonstrated that ARH3 confers protection against hydrogen peroxide (H2O2) exposure, by lowering cytosolic and nuclear PAR levels and preventing apoptosis-inducing factor (AIF) nuclear translocation. We identified a family with an ARH3 gene mutation that resulted in a truncated, inactive protein. The 8-year-old proband exhibited a progressive neurodegeneration phenotype. In addition, parthanatos was observed in neurons of the patient's deceased sibling, and an older sibling exhibited a mild behavioral phenotype. Consistent with the previous findings, the patient's fibroblasts and ARH3-deficient mice were more sensitive, respectively, to H2O2 stress and cerebral ischemia/reperfusion-induced PAR accumulation and cell death. Further, PARP1 inhibition alleviated cell death and injury resulting from oxidative stress and ischemia/reperfusion. PARP1 inhibitors may attenuate the progression of neurodegeneration in affected patients with ARH3 deficiency.

In vivo evaluation of the genotoxicity and oxidative damage in individuals exposed to 10% hydrogen peroxide whitening strips.

OBJECTIVE: This study assessed the impact of 10% hydrogen peroxide whitening strip exposure on the genotoxicity and oxidative damage by means of the buccal micronucleus cytome assay by counting nuclear abnormalities (NAs) in buccal mucosa and attached gingiva cells and by analyzing in whole saliva the molecule 8-hydroxy-2'-deoxyguanosine (8-OHdG). MATERIALS AND METHODS: The study was conducted on 113 subjects divided into two groups: group 1 or control (n = 53), non-whitening strip exposed, and group 2 (n = 60), whitening strip exposed (Crest® 3D Whitestrips® premium plus, 10% hydrogen peroxide). Oral epithelial cells and whole saliva samples were taken at the beginning and 30 days later for group 1 and immediately before bleaching and 15 and 30 days after the end of the bleaching for group 2. RESULTS: An increased frequency of NAs (p < 0.05) and higher levels of 8-OHdG (p < 0.05) were observed after bleaching exposure. Also, a positive correlation exists between oxidative stress produced by hydrogen peroxide and micronuclei was found. CONCLUSION: Individuals exposed to 10% hydrogen peroxide whitening strips exhibit NAs increased in oral epithelial cells and 8-OHdG in saliva, which is directed related to nuclear and oxidative DNA damage, respectively. CLINICAL SIGNIFICANCE: Hydrogen peroxide is the active agent of tooth whitening and this compound induced DNA damage. Individuals exposed to whitening strips with 10% hydrogen peroxide exhibit increased genotoxic and oxidative damage. Therefore, self-application of bleaching agents should be handled carefully since it could be a risk to human health.

Deterioro genómico y manipulación genética: desequilibrio en la prioridad de las agendas públicas / Genome damage and genetic manipulation: unbalance in public policies priority

Se analiza el desequilibrio en el tratamiento de dos temas que atañen a la conservación de la integridad del genoma humano: las tecnologías de manipulación genética y el deterioro genómico provocado por la contaminación ambiental. Las carencias educativas, la falta de información asentada en los hechos y un manejo sensacionalista en los medios, entre otros factores, desajustan las agendas mediáticas con las necesidades públicas, lo que desemboca en una falta de conciencia ciudadana acerca de las verdaderas amenazas a las que está expuesto el material genético y los riesgos de salud que ello implica.

Unbalance in the treatment of two topics related to the conservation of the human genome integrity is analyzed here: the technologies for genetic manipulation and genome damage due to environmental pollution. Lack of education and of information based on real facts, and the media sensationalist treatment, among other factors, provoke an unbalance between the media agenda and public needs. This leads to a lack of citizenship consciousness over the true threats that genetic material faces and the health risks that it involves.

O presente texto analisa o desequilíbrio no tratamento de dois temas que dizem respeito à conservação da integridade do genoma humano: as tecnologias de manipulação genética e a deteriorização genômica provocada pela contaminação ambiental. As carências educativas, a falta de informação assentada nos fatos e um manejo sensacionalista dos meios, entre outros fatores, desajustam as agendas mediáticas com as necessidades públicas, o que desemboca numa falta de consciência cidadã em relação às verdadeiras ameaças à que se expôs o material genético e os riscos de saúde que isto implica.