Atividade antineoplásica in vitro e in vivo de 4’-cloro-1-nitro-2-fenileteno em modelo de Melanoma

Abstract

Unlike most other tumors, the incidence of malignant cutaneous melanoma has increased in the last 30 years. This is responsable for 75% of skin cancer deaths. Many molecular pathways involved in melanomogenesis have already been identified. However, there is still no chemotherapy protocol that guarantees long-term life expectancy. Nitrostyrene compounds are related to antitumor activities since 1975, however, there are no reports of this efficacy on melanoma. In vitro and in vivo antineoplastic effects of the synthetic nitrostyrene derivative 4-chloro-1-nitro-2-phenylethene (7E) were tested in several cell lineages, especially melanoma (SK-Mel-3 and B16F10). Cell viability was assessed by the Alamar Blue® test. Cell cycle, apoptosis, reactive oxygen species (ROS) and mitochondrial depolarization were evaluated by flow cytometry. Caspases 9 and 3, JNK, p38, Bcl-2 and ERK expressions were determined by western blotting. We performed the murine melanoma model to verify the efficacy and toxicity in vivo. Our observations indicate that 7E is cytotoxic to several neoplastic lines, especially melanoma, IC50 of 3.13 μg/mL in SK-Mel-3 and 1.48 μg/mL in B16F10. We found out that 7E increased the level of intracellular reactive oxigen and nitrogen species (ROS/RNS). Furthermore, it increased expression of JNK, p38 and ERK, and reduced expression of Bcl-2. This leads to mitochondrial depolarization, possibly permeabilization of the outer membrane of the mitochondria and the release of cytotoxic proteins (DIABLO / Smac, AIF, ENDOG and CYTC), and the activation of caspase-9 and caspase-3, resulting in apoptotic cell death. The effects of 7E are antagonized by antioxidant pretreatment, confirming the unequivocal importance of increased ROS/RNS in this process. 7E also suppressed in vivo tumor growth by up to 47.8% under the tested conditions. The systemic toxic effect investigation revealed few significant alterations, highlighting the increase of serum urea biochemical dosage. There were no relevant changes in body mass, organ mass and haematological parameters. Tumor histology revealed necrosis and inflammation with microabcess areas, as well as invasion of adipose tissue with phagocytic reaction in animals treated with 7E. Animals treated with 7E had moderate hepatic alterations including necrosis, degeneration and congestion, renal alterations such as focal congestion, hemorrhage and glomerular sclerosis, reduction of the occurrence of pulmonary metastasis and maintenance of the architecture and normal cardiac morphology. Our findings suggest that 7E may have the potential to be further developed as an anticancer compound, especially for melanoma.