Isaac, D. | Search bioRxiv

bioRxiv2020

Enhancing c-MYC degradation via 20S proteasome activation induces in vivo anti-tumor efficacy

Enhancing proteasome activity is a potential new therapeutic strategy to prevent the accumulation of aberrant high levels of protein that drive the pathogenesis of many diseases. Herein, we examine the use of small molecules to activate the 20S proteasome to reduce aberrant signaling by the undruggable oncoprotein c-MYC, to treat c-MYC driven oncogenesis. Overexpression of c-MYC is found in more than 50% of all human cancer but remains undruggable because of its highly dynamic intrinsically disordered 3-D conformation, which renders traditional therapeutic strategies largely ineffective. We demonstrate herein that small molecule activation of the 20S proteasome targets dysregulated intrinsically disordered proteins (IDPs), including c-MYC, and reduces cancer growth in vitro and in vivo models of multiple myeloma, and is even effective in bortezomib resistant cells and unresponsive patient samples. Genomic analysis of various cancer pathways showed that proteasome activation results in downregulation of many c-MYC target genes. Moreover, proteasome enhancement was well tolerated in mice and dogs. These data support the therapeutic potential of 20S proteasome activation in targeting IDP-driven proteotoxic disorders, including cancer, and demonstrate that this new therapeutic strategy is well tolerated in vivo.

pharmacology and toxicology↗

bioRxiv2020

Variability in Fruit Yield and Quality of Genetically Diverse Tomato Cultivars in Response to Different Biochars

Background Intensive agricultural practices have reduced soil health thereby negatively impacting crop yields. There is a need to maintain healthy soils and restore marginal lands to ensure efficient food production. Biochar, a porous carbon-rich material generated from pyrolysis of various feedstock sources is receiving attention as a soil amendment that has the potential to restore soil organic carbon content and also enhance crop yields. However, the physical and chemical properties of biochar are influenced by pyrolysis parameters. These in turn determine its interaction with the soil, thereby influencing its biological properties in terms of impact on soil microcosm and plant productivity. While most studies report the evaluation of one biochar and a single plant cultivar, the role of the plant’s genetic background in responding to biochar as a soil amendment remains unanswered. The impact of six distinct biochars on agronomic performance and fruit quality of three genetically diverse tomato (Solanum lycopersicum) cultivars was evaluated to test the hypotheses that 1) biochars derived from different feedstock sources would produce unique phenotypes in a single cultivar of tomato, and 2) single feedstock-derived BC would produce different phenotypes in each of the three tomato cultivars.Results Different biochars impacted shoot dry weight, total fruit weight, and yield per plant in each cultivar differently. Both positive and negative effects were observed depending on the biochar-cultivar combination. In ‘Oregon Spring’, Ryegrass straw and CoolTerra biochar enhanced yield. In ‘Heinz’, an increase in fruit weight and citric acid was observed with several of the biochars. In ‘Cobra’, improved yields were accompanied by reduction in fruit quality parameters. Both hypotheses were supported by the data.Conclusions This study demonstrated that the genetic background of a plant is an important variable in determining the outcome of using biochar as a soil amendment. Strategies for application of biochar in agricultural production should consider the variables of soil type, feedstock source, pyrolysis parameters and plant genetic background for enhancing crop productivity and carbon sequestration.Competing Interest StatementAD serves as a consultant for AgEnergy Solutions, a biochar production startup company based in Spokane, WA, USA. AgEnergy Solutions had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.AbbreviationsBCBiocharSOMsoil organic matterSOCsoil organic carbonCTCool Terra®RGSRyegrass strawRGTRyegrass tailingsRTRussian thistleTMPThermomechanical pulpWWalnutSEMScanning Electron MicroscopyEXenergy-dispersive X-ray spectroscopy – EDXw/wweight/weightHigh Pressure SodiumHPStotal soluble solidsTSSNnitrogenPphosphorusKpotassiumCacalciumSsulfurMgmagnesiumMomolybdenumSisiliconClchlorineNasodiumAlaluminumView Full Text

plant biology↗