DNA Damage-Inducing 10-Methoxy-canthin-6-one (Mtx-C) Promotes Cell Cycle Arrest in G2/M and Myeloid Differentiation of Acute Myeloid Leukemias and Leukemic Stem Cells.

Synthetic 10-methoxy-canthin-6-one (Mtx-C), an alkaloid derivative, exhibits cytotoxic effects against acute myeloid cells (AMLs) and leukemic stem cells (LSCs) at a concentration of approximately 60 µM. However, the antitumor mechanism of Mtx-C in AMLs and LSCs remains elusive. Using Mtx-C at concentrations with low cytotoxicity (2-4 µM) for 72 h, we observed cell arrest with the accumulation of cells in the G2/M phase of the cell cycle. This effect was controlled by cyclin B1 expression and induction of the DNA damage cascade characterized by ATM, ATR, Chk1/2, p53, and H2A.X phosphorylation. Molecular docking analysis confirmed Mtx-C as a DNA intercalator. Moreover, the expression of inhibitors of cyclin-dependent kinases, including p21 (Cip1) and p27 (Kip1), increased. In addition, several miRNAs that are considered oncosuppressors were regulated by Mtx-C in Kasumi-1 cells. Finally, concomitant with cell cycle arrest, the underlying molecular mechanisms of Mtx-C in AML cells include myeloid differentiation, as evidenced by the increased expression of PU.1, myeloperoxidase, CD15, CD11b, and CD14 in the AML and LSC populations with the participation of p38 mitogen-activated protein kinase. Thus, we showed that Mtx-C simultaneously induced cell cycle arrest and myeloid differentiation in AML lineages and in the LSC population, providing insights into new therapeutic alternatives for the treatment of AML based on naturally occurring molecules.

First generation of multifunctional peptides derived from latarcin-3a from Lachesana tarabaevi spider toxin.

The need for discovering new compounds that can act selectively on pathogens is becoming increasingly evident, given the number of deaths worldwide due to bacterial infections or tumor cells. New multifunctional biotechnological tools are being sought, including compounds present in spider venoms, which have high biotechnological potential. The present work aims to perform the rational design and functional evaluation of synthetic peptides derived from Lachesana tarabaevi spider toxin, known as latarcin-3a. The antimicrobial activity was tested against Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MIC) between 4 and 128 µg.ml-1. Anti-biofilm tests were then performed to obtain MICs, where the peptides demonstrated activity from 4 to 128 µg.ml-1. In vitro cell cytotoxicity assays were carried out from tumor cell lines, lineages C1498, Kasumi-1, K-562, Jurkat, MOLT4, and Raji. Erythrocyte integrity was evaluated in the presence of synthetic peptides analog, which did not promote hemolysis at 128 µg.ml-1. The peptide that showed the best antibacterial activity was Lt-MAP3 and the best antitumor was Lt-MAP2. In conclusion, rational design of multifunctional antimicrobial peptides may be promising alternative tools in the treatment of emerging diseases such as bacterial infections and tumor cells.

Chemodiversity and Anti-Leukemia Effect of Metabolites from Penicillium setosum CMLD 18.

Penicillium setosum represents a Penicillium species recently described, with little up-to-date information about its metabolic and biological potential. Due to this scenario, we performed chemical and biological studies of P. setosum CMLD18, a strain isolated from Swinglea glutinosa (Rutaceae). HRMS-MS guided dereplication strategies and anti-leukemia assays conducted the isolation and characterization of six compounds after several chromatographic procedures: 2-chloroemodic acid (2), 2-chloro-1,3,8-trihydroxy-6- (hydroxymethyl)-anthraquinone (7), 7-chloroemodin (8), bisdethiobis(methylthio)acetylaranotine (9), fellutanine C (10), and 4-methyl-5,6-diihydro-2H-pyran-2-one (15). From the assayed metabolites, (10) induced cellular death against Kasumi-1, a human leukemia cell line, as well as good selectivity for it, displaying promising cytotoxic activity. Here, the correct NMR signal assignments for (9) are also described. Therefore, this work highlights more detailed knowledge about the P. setosum chemical profile as well as its biological potential, offering prospects for obtaining natural products with anti-leukemia capabilities.

A canthin-6-one derivative induces cell death by apoptosis/necroptosis-like with DNA damage in acute myeloid cells.

Natural products have long been considered a relevant source of new antitumor agents. Despite advances in the treatment of younger patients with acute myeloid leukemia (AML), the prognosis of elderly patients remains poor, with a high frequency of relapse. The cytotoxicity of canthin-6-one alkaloids has been extensively studied in different cell types, including leukemic strains. Among the canthin-6-one analogs tested, 10-methoxycanthin-6-one (Mtx-C) showed the highest cytotoxicity in the malignant AML cells Kasumi-1 and KG-1. Thus, we evaluated the cytotoxicity and cell death mechanisms related to Mtx-C using the EC50 (80 µM for Kasumi-1 and 36 µM for KG-1) treatment for 24 h. Our results identify reactive oxygen species production, mitochondrial depolarization, annexin V-FITC/7-AAD double staining, caspase cleave and upregulation of mitochondria-dependent apoptosis proteins (Bax, Bim, Bik, Puma and phosphorylation of p53) for both cell lineages. However, downregulation of Bcl-2 and the simultaneous execution of the apoptotic and necroptotic programs associated with the phosphorylation of the proteins receptor-interacting serine/threonine-protein kinase 3 and mixed lineage kinase domain-like pseudokinase occurred only in Kasumi-1 cells. About the lasted events, Kasumi-1 cell death was inhibited by pharmacological agents such as Zvad-FMK and necrostatin-1. The underlying molecular mechanisms of Mtx-C still include participation in the DNA damage and stress-signaling pathways involving p38 and c-Jun N-terminal mitogen-activated protein kinases and interaction with DNA. Thus, Mtx-C represents a promising tool for the development of new antileukemic molecules.

α-amyrin-loaded nanocapsules produce selective cytotoxic activity in leukemic cells.

INTRODUCTION: Amyrins are triterpenes that have attractive pharmacological potential; however, their low water solubility and erratic stomach absorption hinders their use as a drug. The aim of this paper was to develop a novel α-amyrin-loaded nanocapsule for intestinal delivery and evaluate, preliminarily, its cytotoxic ability against leukemic cells. MATERIAL AND METHODS: Five nanocapsule formulations were designed by the solvent displacement-evaporation method. Poly-ε-caprolactone, Eudragit® E100, and Kollicoat® Mae 100 P were used as film-former materials. Particle size, polydispersity index (PdI), zeta potential, and the pH of all formulations were measured. The cytotoxic potential of the nanocapsules was evaluated in vitro using different leukemic lineages RESULTS: Nanocapsules coated with Kollicoat® Mae 100 P presented the smallest particle size (130 nm), the lowest zeta-potential (-38 mV), and the narrowest size distribution (PdI = 0.100). The entrapment efficiency was 65.47%, while the loading capacity was 2.40%. Nanocapsules release 100% of α-amyrin in 40 min (pH 7.4), by using a possible mechanism of swelling-diffusion. The formulation showed excellent on-shelf physicochemical stability during one year. Additionally, nanocapsules produced a selective cytotoxic effect on a human leukemia lineage Kasumi-1, an acute myeloid leukemia cell line, and produced cell death by apoptosis CONCLUSION: α-amyrin-loaded nanocapsules appear to be a promising nanoformulation that could be used against leukemia.