Chloroacridine derivatives as potential anticancer agents which may act as tricarboxylic acid cycle enzyme inhibitors.

PURPOSE: This paper concerns the cytotoxicity of 9-chloro-1-nitroacridine (1a) and 9-chloro-4-methyl-1-nitroacridine (1b) against two biologically different melanoma forms: melanotic and amelanotic. Melanomas are tumors characterized by high heterogeneity and poor susceptibility to chemotherapies. Among new analogs synthesized by us, compound 1b exhibited the highest anticancer potency. Because of that, in this study, we analyzed the mechanism of action for 1a and its 4-methylated derivative, 1b, against a pair of biological melanoma forms, with regard to proliferation, cell death mechanism and energetic state. METHODS: Cytotoxicity was evaluated by XTT assay. Cell death was estimated by plasma membrane structure changes (phosphatidylserine externalization), caspase activation, and ROS presence. The energetic state of cells was estimated based on NAD and ATP levels, and the activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, isocitrate dehydrogenase). RESULTS: The chloroacridines affect biological forms of melanoma in different ways. Amelanotic (Ab) melanoma (with inhibited melanogenesis and higher malignancy) was particularly sensitive to the action of the chloroacridines. The Ab melanoma cells died through apoptosis and through death without caspase activation. Diminished activity of TAC enzymes was noticed among Ab melanoma cells together with ATP/NAD depletion, especially in the case of 1b. CONCLUSION: Our data show that the biological forms of the tumors responded to 1a and its 4-methylated analog in different ways. 1a and 1b could be inducers of regulated melanoma cell death, especially the amelanotic form. Although the mechanism of the cell death is not fully understood, 1b may act by interfering with the TAC enzymes and blocking specific pathways leading to tumor growth. This could encourage further investigation of its anticancer activity, especially against the amelanotic form of melanoma.

Synthesis and Biological Evaluation of Acridine/Acridone Analogs as Potential Anticancer Agents.

BACKGROUND: The lack of efficacious therapy for advanced melanoma and neuroblastoma makes new approaches necessary. Therefore, many scientists seek new, more effective, more selective and less toxic anticancer drugs. OBJECTIVE: We propose the synthesis of the new functionalized analogs of 1-nitroacridine/4- nitroacridone connected to tuftsin/retro-tuftsin derivatives as potential anticancer agents. METHODS: Acridine and acridone analogues were prepared by Ullmann condensation and then cyclization reaction. As a result of nucleophilic substitution reaction 1-nitro-9-phenoxyacridine or 1- chloro-4-nitro-9(10H)-acridone with the corresponding peptides, the planned acridine derivatives (10a-c, 12, 17-a-d, 19) have been obtained. The cytotoxic activity of the newly obtained analogs were evaluated against melanotic (Ma) and amelanotic (Ab) melanoma cell lines and neuroblastoma SH-SY5Y by using the XTT method. Apoptosis and cell cycle were analyzed by flow cytometry. RESULTS: Among the investigated analogs compound 12 exhibited the highest potency comparable to dacarbazine action for amelanotic Ab melanoma cells. FLICA test (flurochrome-labeled inhibitors of caspases) showed that this analog significantly increased the content of cells with activated caspases (C+) among both neuroblastoma lines and only Ab melanoma line. Using phosphatidylserine (PS) externalization assay, 12 induced changes in the Ab melanoma plasma membrane structure as the externalization of phosphatidylserine (An+ cells). These changes in neuroblastoma cells were less pronounced. CONCLUSION: Analog 12 could be proposed as the new potential chemotherapeutic against amelanotic melanoma form especially.

Novel therapeutic compound acridine-retrotuftsin action on biological forms of melanoma and neuroblastoma.

PURPOSE: As a continuation of our search for anticancer agents, we have synthesized a new acridine-retrotuftsin analog HClx9-[Arg(NO2)-Pro-Lys-Thr-OCH3]-1-nitroacridine (named ART) and have evaluated its activity against melanoma and neuroblastoma lines. Both tumors develop from cells (melanocytes, neurons) of neuroectodermal origin, and both are tumors with high heterogeneity and unsatisfactory susceptibility to chemotherapies. Thus, we analyzed the action of ART on pairs of biological forms of melanoma (amelanotic and melanotic) and neuroblastoma (dopaminergic and cholinergic) with regard to proliferation, mechanism of cell death, and effect on the activity of tricarboxylic acid cycle (TAC) enzymes. METHODS: The cytotoxicity of ART was evaluated by XTT and trypan blue tests. Cell death was estimated by plasma membrane structure changes (phosphatidylserine and calreticulin externalization), caspase activation, presence of ROS (reactive oxygen species), activity of tricarboxylic acid cycle enzymes (pyruvate dehydrogenase complex, aconitase, and isocitrate dehydrogenase), NAD level, and ATP level. RESULTS: ART influences the biological forms of melanoma and neuroblastoma in different ways. Amelanotic (Ab) melanoma (with the inhibited melanogenesis, higher malignancy) and SHSY5Y neuroblastoma (with cholinergic DC cells) were especially sensitive to ART action. The Ab melanoma cells died through apoptosis, while, with SH-SY5Y-DC neuroblastoma, the number of cells decreased but not as a result of apoptosis. With Ab melanoma and SH-SY5Y-DC cells, a diminished activity of TAC enzymes was noticed, along with ATP/NAD depletion. CONCLUSION: Our data show that the biological forms of certain tumors responded in different ways to the action of ART. As a combination of retrotuftsin and acridine, the compound can be an inducer of apoptotic cell death of melanoma, especially the amelanotic form. Although the mechanism of the interrelationships between energy metabolism and cell death is not fully understood, interference of ART with TAC enzymes could encourage the further investigation of its anticancer action.

Tuftsin - Properties and Analogs.

BACKGROUND: Immunomodulation is one of the significant therapeutic strategies. It includes both stimulation and suppression of the immune system by a variety of substances called immunomodulators, designed to regulate the immune response of the organism against infections of varying etiology. An example of such a substance is tuftsin (TKPA) 3 (Fig. (1)). In this paper were included tuftsin derivatives, which were described over the years, their together with biological activity and clinical potential. METHODS: We reviewed a bibliographic database to gather all the important information about the tuftsin peptide. We have delineated the significant information on the activity of the tetrapeptide itself and its derivatives. Analogs were divided because of their anti-tumor, anti-inflammatory, antimicrobial and anti-viral activity. RESULTS: This paper describes eighty-six documents. Thirty-two of them concern on activity of tuftsin in the human organism. The remaining fifty-four describe peptide analogues and their properties, including eleven papers about the tuftsin-based peptides contained in the vaccines, nine papers representing anticancer activity of the tuftsin derivatives, twenty-six about antiinflammatory compounds, and five papers describing the antitumor activity of the tuftsin analogs. CONCLUSION: The findings of this review confirm the importance of the tuftsin and their derivatives. Most of these substances showed anti-tumor, anti-inflammatory or antibacterial activities. A large amount of the compounds may find use in vaccines. Tuftsin can also be used to prepare fusion proteins in the treatment of cancer and as carriers of many biologically active substances.