Benzofuroxan derivatives N-Br and N-I induce intrinsic apoptosis in melanoma cells by regulating AKT/BIM signaling and display anti metastatic activity in vivo

A limitless Brazilian scientist: Professor Travassos and his contribution to cancer biology

Luiz Rodolpho Travassos, a Brazilian scientist recognized in several areas of research, began his studies in the field of oncology in the late 1970s when he took a sabbatical at the Memorial Sloan Kettering Cancer Center, NY, USA. At that time, the discovery and characterization of human melanoma glycoprotein antigens yielded important publications. This experience allowed 16 years later, and Dr. Travassos founded UNONEX, significantly contributing with discoveries in the area of oncology and training of researchers. This review will address all the contributions of team of researchers who, together with Dr. Travassos, collaborated with investigations into molecules and processes that lead to the development of melanoma.

Activity of compounds derived from benzofuroxan in Trichomonasvaginalis

Trichomoniasis is a sexually transmitted infection caused by the protozoan Trichomonas vaginalis. Currently, trichomoniasis is treated with the class of nitroimidazoles, namely, metronidazole; however, resistant isolates and strains have been reported. The compounds derived from benzofuroxan are biologically active heterocycles. This study evaluated the in vitro antiparasitic activity of these compounds in trophozoites of T. vaginalis and determined the mean inhibitory concentration (IC50), minimum inhibitory concentration (MIC), mortality curve, and cytotoxicity. The compounds were named EH1, EH2, EH3, and EA2 and tested in various concentrations: 100 to 15 μM (EH1 and EH2); 100 to 5 μM (EH3); and 100 to 25 μM (EA2), respectively. The greatest efficacy was observed in the highest concentrations in 24 h, with inhibition of approximately 100% of trophozoites. Compounds EH2 and EH3 had the lowest MIC: EH2 (35 μM) and EH3 (45 μM), with IC50 of 11.33 μM and 6.83 μM, respectively. Compound EA2 was effective at the highest concentrations. The activity of the compounds in T. vaginalis started in the first hour of incubation with 90% inhibition; after 12 h, inhibition >95% was observed. Compound EH1 showed the lowest activity, with the highest activity between 12 and 24 h after incubation. These results demonstrate that benzofuroxan derivatives are promising compounds for the in vitro treatment of T. vaginalis.

Water-Soluble Salts Based on Benzofuroxan Derivatives-Synthesis and Biological Activity

A series of novel water-soluble salts of benzofuroxans was achieved via aromatic nucleophilic substitution reaction of 4,6-dichloro-5-nitrobenzofuroxan with various amines. The salts obtained showed good effectiveness of the pre-sowing treatment of seeds of agricultural crops at concentrations of 20-40 mmol. In some cases, the seed treatment with salts leads not only to improved seed germination, but also to the suppression of microflora growth. Additionally, their anti-cancer activityin vitrohas been researched. The compounds with morpholine fragments or a fragment of N-dimethylpropylamine, demonstrated the highest cytotoxic activity, which is in good correlation with the ability to inhibit the glycolysis process in tumor cells. Two compounds 4e and 4g were selected for further experiments using laboratory animals. It was found that the lethal dose of 50% (LD50) is 22.0 ± 1.33 mg/kg for 4e and 13.75 ± 1.73 mg/kg for 4g, i.e., compound 4e is two times less toxic than 4g, according to the mouse model in vivo. It was shown that the studied compounds exhibit antileukemia activity after a single intraperitoneal injection at doses from 1.25 to 5 mg/kg, as a result of which the average lifespan of animals with a P388 murine leukemia tumor increases from 20 to 28%. Thus, the water-soluble salts of benzofuroxans can be considered as promisingcandidates for further development, both as anti-cancer agents and as stimulants for seed germination and regulators of microflora crop growth.

ROS as Regulators of Cellular Processes in Melanoma

In this review, we examine the multiple roles of ROS in the pathogenesis of melanoma, focusing on signal transduction and regulation of gene expression. In recent years, different studies have analyzed the dual role of ROS in regulating the redox system, with both negative and positive consequences on human health, depending on cell concentration of these agents. High ROS levels can result from an altered balance between oxidant generation and intracellular antioxidant activity and can produce harmful effects. In contrast, low amounts of ROS are considered beneficial, since they trigger signaling pathways involved in physiological activities and programmed cell death, with protective effects against melanoma. Here, we examine these beneficial roles, which could have interesting implications in melanoma treatment.

The Reactivity of Azidonitrobenzofuroxans towards 1,3-Dicarbonyl Compounds: Unexpected Formation of Amino Derivative via the Regitz Diazo Transfer and Tautomerism Study

Herein, we report on the reaction of nitro-substituted azidobenzofuroxans with 1,3-dicarbonyl compounds in basic media. The known reactions of benzofuroxans and azidofuroxans with 1,3-dicarbonyl compounds in the presence of bases are the 1,3-dipolar cycloaddition and the Beirut reaction. In contrast with this, azidonitrobenzofuroxan reacts with 1,3-carbonyl compounds through Regitz diazo transfer, which is the first example of this type of reaction for furoxan derivatives. This difference is seemingly due to the strong electron-withdrawing effect of the superelectrophilic azidonitrobenzofuroxan, which serves as the azido transfer agent rather than 1,3-dipole in this case.

In vitro and in vivo trypanocidal activity of a benzofuroxan derivative against Trypanosoma cruzi

Chagas disease, caused by Trypanosoma cruzi, is a major public health problem and is described as one of the most neglected diseases worldwide. It affects about 6-7 million people. Currently, only two drugs are available for the treatment of this disease: nifurtimox and benznidazole. However, both drugs are highly toxic and have several side effects, which lead many patients to discontinue treatment. Moreover, these compounds show a significant curative efficacy only in the acute phase of the disease. Therefore, searching for new drugs is necessary. The objective of this study was to evaluate the in vitro and in vivo activity of a benzofuroxan derivative (EA2) against T. cruzi, and to evaluate the hematological and biochemical changes induced by its treatment in animals infected with T. cruzi. The results were then compared with those of healthy controls. In vitro testing was first performed with T. cruzi epimastigote forms. In this experiment, EA2 was diluted at three different concentrations (0.25, 0.50, and 1%). In vitro evaluation of the trypanocidal activity was performed 24, 48, and 72 h after incubation. In vivo assays were performed using three different doses (10, 5, and 2,5 mg/kg). Mice were divided into 10 groups (five animals/group), wherein four groups comprised non-infected animals (A, G, H, I) and six groups comprised infected animals (B, C, D E, F, J). Groups B and J represented the negative and positive controls, respectively. Groups G, H, and I were used to confirm that EA2 was not toxic to non-infected animals. Parasitemia was measured in infected animals and the hematological and biochemical profiles (urea, creatinine, albumin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) were evaluated in all animals. EA2 demonstrated in vitro trypanocidal activity at all concentrations tested. Although it did not demonstrate a curative effect in vivo, EA2 was able to retard the onset of parasitemia, and significantly reduced the parasite count in groups D and E (treated with 5 and 2.5 mg/kg, respectively). EA2 did not induce changes in hematological and biochemical parameters in non-infected animals, demonstrating that it is not toxic. However, further assessments should aim to confirm the safety of EA2 since this was the first in vitro and in vivo study conducted with this molecule.

Frankincense essential oil suppresses melanoma cancer through down regulation of Bcl-2/Bax cascade signaling and ameliorates heptotoxicity via phase I and II drug metabolizing enzymes

Melanoma is a deadly form of malignancy and according to the World Health Organization 132,000 new cases of melanoma are diagnosed worldwide each year. Surgical resection and chemo/drug treatments opted for early and late stage of melanoma respectively, however detrimental post surgical and chemotherapy consequences are inevitable. Noticeably melanoma drug treatments are associated with liver injuries such as hepatitis and cholestasis which are very common. Alleviation of these clinical manifestations with better treatment options would enhance prognosis status and patients survival. Natural products which induce cytotoxicity with minimum side effects are of interest to achieve high therapeutic efficiency. In this study we investigated anti-melanoma and hepatoprotective activities of frankincense essential oil (FEO) in both in vitro and in vivo models. Pretreatment with FEO induce a significant (p < 0.05) dose-dependent reduction in the cell viability of mouse (B16-F10) and human melanoma (FM94) but not in the normal human epithelial melanocytes (HNEM). Immunoblot analysis showed that FEO induces down regulation of Bcl-2 and up regulation of BAX in B16-F10 cells whereas in FM94 cells FEO induced dose-dependent cleavage of caspase 3, caspase 9 and PARP. Furthermore, FEO (10 μg/ml) treatment down regulated MCL1 in a time-dependent manner in FM94 cells. In vivo toxicity analysis reveals that weekly single dose of FEO (1200 mg/kg body weight) did not elicit detrimental effect on body weight during four weeks of experimental period. Histology of tissue sections also indicated that there were no observable histopathologic differences in the brain, heart, liver, and kidney compare to control groups. FEO (300 and 600 mg/kg body weight) treatments significantly reduced the tumor burden in C57BL/6 mice melanoma model. Acetaminophen (750 mg/kg body weight) was used to induce hepatic injury in Swiss albino mice. Pre treatment with FEO (250 and 500 mg/kg body weight) for seven days retained hematology (complete blood count), biochemical parameters (AST, ALT, ALK, total bilirubin, total protein, glucose, albumin/globulin ratio, cholesterol and triglyceride), and the level of phase I and II drug metabolizing enzymes (cytochrome P450, cytochromeb5, glutathione-S-transferase) which were obstructed by the administration of acetaminophen. Further liver histology showed that FEO treatments reversed the damages (central vein dilation, hemorrhage, and nuclei condensation) caused by acetaminophen. In conclusion, FEO elicited marked anti-melanoma in both in vitro and in vivo with a significant heptoprotection.

Chaetocin induces apoptosis in human melanoma cells through the generation of reactive oxygen species and the intrinsic mitochondrial pathway, and exerts its anti-tumor activity in vivo

Chaetocin is a small-molecule natural product produced by Chaetomium species fungi, and it has a potent anti-proliferative pharmacological activity on various cancer cells. However, the effect of chaetocin on anti-melanoma pharmacological role has not been investigated. Therefore, in this study, we explored the effect of chaetocin on cell proliferation in the human melanoma Sk-Mel-28 and A375 cells and the growth of tumor xenografts in nude mice. The results indicated that chaetocin treatment significantly suppressed cell proliferation and induced apoptosis in the Sk-Mel-28 and A375 cells in a dose- and time-dependent manner. Furthermore, chaetocin treatment resulted in an increased level of cellular reactive oxygen species (ROS), and pre-incubation of cells with N-acetylcysteine (NAC) significantly abrogated chaetocin-induced apoptosis in the melanoma cells. A significant reduction of mitochondrial membrane potential and the release of cytochrome c were observed after chaetocin treatment. Additionally, chaetocin treatment significantly up-regulated the protein levels of Bax, cleaved caspase-9/-3, simultaneously down-regulated the protein levels of Bcl-2, procaspase-9/-3, and activated caspase-9/-3 activity in the melanoma cells. The in vivo data demonstrated that chaetocin treatment significantly inhibited the growth of melanoma tumor xenografts in nude mice, which was closely associated with apoptosis induction, a reduced level of PCNA (proliferating cell nuclear antigen) expression, and activation of capase-9/-3 in tumor xenografts. These are the first data to demonstrate that chaetocin exerts a proapoptotic activity on human melanoma cells through ROS generation and the intrinsic mitochondrial pathway. Therefore, chaetocin might represent an effective candidate for melanoma chemotherapy.

Autophagy: In the cROSshairs of cancer

Two prominent features of tumors that contribute to oncogenic survival signaling are redox disruption, or oxidative stress phenotype, and high autophagy signaling, making both phenomena ideal therapeutic targets. However, the relationship between redox disruption and autophagy signaling is not well characterized and the clinical impact of reactive oxygen species (ROS)-generating chemotherapeutics on autophagy merits immediate attention as autophagy largely contributes to chemotherapeutic resistance. In this commentary we focus on melanoma, using it as an example to provide clarity to current literature regarding the roles of autophagy and redox signaling which can be applicable to initiation and maintenance of most tumor types. Further, we address the crosstalk between ROS and autophagy signaling during pharmacological intervention and cell fate decisions. We attempt to elucidate the role of autophagy in regulating cell fate following treatment with ROS-generating agents in preclinical and clinical settings and discuss the emerging role of autophagy in cell fate decisions and as a cell death mechanism. We also address technical aspects of redox and autophagy evaluation in experimental design and data interpretation. Lastly, we present a provocative view of the clinical relevance, emerging challenges in dual targeting of redox and autophagy pathways for therapy, and the future directions to be addressed in order to advance both basic and translational aspects of this field.