Modulation of autophagy by a thioxanthone decreases the viability of melanoma cells

(1) Background: Our previous studies unveiled the hit thioxanthone TXA1 as an inhibitor of,P-glycoprotein (drug efflux pump) and of human tumor cells growth, namely of melanoma cells. SinceTXA1 is structurally similar to lucanthone (an autophagy inhibitor and apoptosis inducer) and to N10-substituted phenoxazines (isosteres of thioxanthones, and autophagy inducers), this study aimed at further assessing its cytotoxic mechanism and evaluating its potential as an autophagy modulator in A375-C5 melanoma cells; (2) Methods: Flow cytometry with propidium iodide (PI) for cell cycle profile analysis; Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, flow cytometry with Annexin V/PI labeling and Western blot for apoptosis analysis were conducted. A pharmacophore approach was used for mapping TXA1 onto pharmacophores for autophagy induction. Autophagy analyses included transmission electron microscopy for visualization of autophagic structures, fluorescence microscopy for observation of monodansylcadaverine (MDC) staining, pattern of LC3 expression in the cells and acridine orange staining, and Western blot for autophagic proteins expression; (3) Results: TXA1 induced autophagy of melanoma cells at the GI50 concentration (3.6 μM) and apoptosis at twice that concentration. Following treatment with TXA1, autophagic structures were observed, together with the accumulation of autophagosomes and the formation of autophagolysosomes. An increase in LC3-II levels was also observed, which was reverted by 3-methyladenine (3-MA) (an early stage autophagy-inhibitor) but further increased by E-64d/pepstatin (late-stage autophagy inhibitors). Finally, 3-MA also reverted the effect of TXA1 in cellular viability; (4) Conclusion: TXA1 decreases the viability of melanoma cells by modulation of autophagy and may, therefore, serve as a lead compound for the development of autophagy modulators with antitumor activity.This work was financed by FEDER—Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT—Fundação para a Ciência e a Tecnologia/ Ministério da Ciência, Tecnologia e Inovação in the framework of the project “Institute for Research and Innovation in Health Sciences (POCI-01-0145-FEDER-007274)”. The work was also funded by ERDF, COMPETE, and FCT under the projects PTDC/SAU-OSM/101437/2008, PTDC/MAR-BIO/4694/2014, and INNOVMAR—reference NORTE-01-0145-FEDER-000035, Research Line NOVELMAR. The authors also thank: FCT for D. Sousa and R.T. Lima grants (PTDC/SAU-FCT/100930/2008 and SFRH/BPD/68787/2010, respectively), QREN for D. Sousa grant (NORTE-07-0124-FEDER-000023)

Aptidões de genótipos de batata-doce para consumo humano, produção de etanol e alimentação animal

O objetivo deste trabalho foi identificar a aptidão de genótipos de batata-doce (Ipomoea batatas) para consumo humano, produção de etanol e alimentação animal, por meio de índices de aptidão. Os índices de aptidão corresponderam às médias dos valores das variáveis padronizadas para 16 características de interesse, ponderadas por pesos atribuídos a cada característica, conforme a aptidão avaliada. Utilizou-se o delineamento experimental de blocos ao acaso, com duas repetições e 39 genótipos: 36 acessos da coleção de germoplasma da Universidade Federal de Lavras e três cultivares comerciais (Palmas, Brazlândia-Branca e Brazlândia-Rosada). Oito genótipos foram considerados aptos à produção de etanol, 11 à alimentação animal e 11 ao consumo humano, incluindo as cultivares Palmas e Brazlândia-Branca. Os acessos UFLA07-12, UFLA07-31, UFLA07-43, UFLA07-49 e UFLA07-53 apresentaram aptidão para produção de etanol, alimentação animal e consumo humano. O índice de seleção é eficiente para estabelecer aptidões para genótipos de batata-doce