Efeito antitumoral in vitro de um composto de selênio em linhagem humana de câncer do colo do útero

Abstract

Cervical cancer (CC) exhibits a high global prevalence. Despite the advances achieved in CC treatment, chemotherapy still presents limitations such as significant side effects and tumor cell resistance to cytotoxic agents. Therefore, there is an emerging need for new therapeutic alternatives that are less toxic and more selective toward malignant cells. The aim of this study was to investigate the in vitro antitumor activity of the selenium compound N-(4-nitrophenyl)benzoseleno-ethylenolactamide (SeNitro) in a cervical cancer cell line. The cytotoxicity of SeNitro was assessed using the MTT assay in human tumor cell lines (SK-MEL-28, HeLa, HCT-116, MCF-7, and MDA-MB-231) and a non-tumor cell line (HEK-293). The type of cell death induced by the test molecule was investigated by laser confocal microscopy using acridine orange (AO) and propidium iodide (PI), Hoechst 34580, or JC-1. To evaluate the involvement of ROS and MAPKs in SeNitro-induced cytotoxicity, the MTT assay was performed in the presence or absence of NAC and in the presence or absence of MAPK inhibitors, respectively. After 72 h, SeNitro showed an IC₅₀ of 5.03 ± 0.45 μM for the HeLa cervical cancer cell line, which was the most sensitive to treatment. For the non-tumor cell line, SeNitro presented an IC₅₀ of 93.00 ± 16.13 μM. Based on these results, the Selectivity Index (SI) of SeNitro was determined, showing that the compound was 18 times more selective for the tumor cell line (SI = 18.49). In the AO/PI assay, after 24 h of treatment with SeNitro, a significant increase in early apoptosis was observed in HeLa cells (2.5 μM: 83.76 ± 4.23%; 5.0 μM: 81.72 ± 1.21%; 10 μM: 84.25 ± 2.07%; p < 0.0001 for all). In the Hoechst 34580 assay, a significant increase in fluorescence intensity was observed in HeLa cells following treatment with SeNitro (5 μM: 240.0 ± 6.93%; 10 μM: 254.1 ± 4.78%; p < 0.0001). In the JC-1 assay, a decrease in the aggregate/monomer fluorescence ratio was observed after treatment with the test molecule (5 μM: 0.24 ± 0.02; 10 μM: 0.20 ± 0.01; p < 0.0001). Pre-treatment with NAC significantly prevented SeNitro-induced cytotoxicity (5 μM: 97.57 ± 3.88%; 10 μM: 80.44 ± 2.10%; p < 0.0001) compared to the group treated with SeNitro in the absence of NAC (5 μM = 54.50 ± 1.49%; 10 μM = 39.20 ± 1.71%). Additionally, pre-treatment with ERK and JNK inhibitors significantly reduced cell viability after SeNitro treatment (with ERK inhibitor = 35.02 ± 1.00%; with JNK inhibitor = 39.58 ± 3.04%; p < 0.05 for both) compared to the group treated with SeNitro alone (58.73 ± 6.79%; p < 0.05). Taken together, these results indicate that SeNitro exhibits high selectivity toward HeLa cells and induces apoptosis in this cell line through a mechanism dependent on oxidative stress and inhibition of ERK and JNK signaling pathways.