Efeito citotóxico do composto de selênio N-(4-metilfenil)benzoseleno-etilenolactamida em linhagem de câncer do colo do útero

Abstract

Cervical cancer is one of the main malignant tumors affecting women and is strongly associated with persistent infection by the human papillomavirus (HPV). Despite advances in screening and treatment, available therapies still present limitations related to toxicity and tumor resistance, reinforcing the need for new therapeutic alternatives. The compound N-(4-methylphenyl)benzoseleno-ethylenolactamide (SeB2) has drawn attention due to its broad spectrum of biological activities, including leishmanicidal and antimicrobial effects, as well as its low toxicity in experimental models. In this context, the aim of this study was to investigate the cytotoxic effect and type of cell death induced by SeB2 in HeLa cells. Cytotoxicity was assessed using the MTT assay in the tumor cell lines SK-MEL-28, HeLa, HCT-116, and MCF-7, and in the non-tumor cell line HEK293. The IC₅₀ values were 5.03 ± 0.32 μM for HeLa and 30.22 ± 2.70 μM for HEK293. Based on these results, the selectivity index (SI) indicated that SeB2 was six times more selective for HeLa cells than for the other tested cell lines.The type of cell death was determined by acridine orange/propidium iodide staining under confocal microscopy, revealing a significant increase in the percentage of cells in early apoptosis (2.5 μM: 86.23 ± 3.56%; 5.0 μM: 78.34 ± 8.77%; 10 μM: 35.62 ± 8.06%; p < 0.05 for all) and in late apoptosis/necrosis (10 μM: 64.38 ± 8.06%; p < 0.05), along with morphological changes such as membrane blebbing, chromatin condensation, and nuclear fragmentation, typical features of apoptosis. The Hoechst 34580 assay confirmed these findings, showing a significant increase in fluorescence of 85 ± 7.16% and 153 ± 6.01% at 5 and 10 μM, respectively. The involvement of the mitochondrial membrane potential was also evaluated, revealing a significant decrease in the JC-1 aggregate/monomer fluorescence ratio, from 2.01 in the control to 0.27 and 0.22 at 5 and 10 μM, respectively (p < 0.05). To determine whether apoptosis was associated with oxidative stress, cells were pre-treated with N-acetylcysteine (NAC, 5 mM), which significantly prevented the cytotoxic effect of SeB2 (5 μM: 100.60 ± 2.9%; 10 μM: 88.71 ± 2.28%; p < 0.05 for both), suggesting an oxidative mechanism of SeB2 in HeLa cells. Finally, the involvement of the MAPK pathways was evaluated using inhibitors of MEK/ERK1/2 (U0126), JNK (SP600125), and p38 MAPK (PD169316) through the MTT assay. The combination of the JNK inhibitor with SeB2 significantly reduced cell viability to 31.63 ± 2.93% (p < 0.05), indicating that SeB2 enhanced cytotoxicity in the presence of JNK inhibition. In conclusion, SeB2 exhibits potential as an antitumor agent against cervical cancer, representing a promising candidate for further preclinical studies.