Banca de DEFESA: ESTEFANIA LINS SECUNDO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ESTEFANIA LINS SECUNDO
DATE: 06/08/2026
TIME: 14:30
LOCAL: Videoconferência
TITLE:

IMPACT OF RETENE ON GENOMIC INTEGRITY AND TELOMERE LENGTH IN A HUMAN PULMONARY CELL LINE

KEY WORDS:

Atmospheric pollution; Polycyclic aromatic hydrocarbons; 7-isopropyl-1-methylphenanthrene; Genomic instability; Telomeres.

PAGES: 90
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Air pollution represents one of the major environmental risk factors for human health, with polycyclic aromatic hydrocarbons (PAHs) being constituents with high genotoxic and carcinogenic potential. Retene (RET; 7-isopropyl-1-methylphenanthrene), an alkylated PAH widely used as a molecular marker of biomass burning, remains poorly investigated regarding its biological effects in human cellular models. In this context, the present study aimed to evaluate the cytotoxic and genotoxic effects, as well as the impacts on relative telomere length, induced by RET exposure in human lung A549 cells, derived from human lung adenocarcinoma. Cells were exposed to RET at concentrations of 10, 30, and 60 ng/mL for 24 hours and were evaluated for cell viability using the MTT assay, primary DNA damage using the alkaline comet assay, chromosomal instability using the cytokinesis-block micronucleus assay (CBMN), and relative telomere length using quantitative real-time polymerase chain reaction (qPCR). In the MTT assay, 24-hour exposure did not promote a significant reduction in cell viability at any of the evaluated concentrations, whereas after 48 hours, statistically significant reductions were observed at all tested concentrations (p < 0.05), characterizing a cytotoxic effect dependent on exposure time. The alkaline comet assay revealed a significant increase in the percentage of DNA in the tail at concentrations of 30 ng/mL (p = 0.0106) and 60 ng/mL (p < 0.0001), indicating the induction of primary DNA damage at subcytotoxic levels. The CBMN assay demonstrated a significant increase in micronucleus frequency at concentrations of 30 ng/mL (p = 0.0305) and 60 ng/mL (p = 0.0003), as well as an increase in nucleoplasmic bridge frequency at 60 ng/mL (p = 0.0282), evidencing chromosomal instability with a profile suggestive of clastogenic activity. The frequency of nuclear buds did not show statistically significant differences at any of the RET concentrations evaluated. Analysis of relative telomere length by qPCR revealed a significant reduction in the T/S ratio at all evaluated concentrations: 10 ng/mL (p = 0.0189), 30 ng/mL (p = 0.0009), and 60 ng/mL (p < 0.0001), with a progressive pattern according to increasing concentration, compared with the negative control. Spearman correlation analysis between relative telomere length and biomarkers of chromosomal instability revealed a strong and significant inverse association with the frequency of nucleoplasmic bridges (rₛ = -0.9161; p < 0.0001) and micronuclei (rₛ = -0.8983; p = 0.0002), indicating that RET-induced telomere shortening occurs in parallel with increased biomarkers of chromosomal instability. The association with nuclear buds showed only a non-significant trend (rₛ = -0.5744; p = 0.0540). Taken together, the results demonstrate that retene is capable of inducing primary DNA damage, chromosomal instability, and relative telomere shortening in human lung cells at concentrations based on previous studies and environmentally related, reinforcing its genotoxic potential and the importance of an integrated assessment of multiple biomarkers for characterizing the effects associated with exposure to PAHs derived from air pollution.

COMMITTEE MEMBERS:
Externa à Instituição - JULIANA DA SILVA - UNILASALLE
Presidente - 1199127 - SILVIA REGINA BATISTUZZO DE MEDEIROS
Interna - 2085604 - SUSANA MARGARIDA GOMES MOREIRA