Isotopics – October 2019 | Edition 10
Welcome to the 10th edition of CIL’s IsoTopics™ mass spec newsletter! We hope you have enjoyed our previous editions, and we appreciate the feedback you have given us through the years.
SILAC Quantitative Proteomics and Biochemical Analyses Reveal a Novel Molecular Mechanism by which ADAM12s Promotes the Proliferation, Migration, and Invasion of Small Cell Lung Cancer Cells through Upregulating Hexokinase1
Duan, Q.; Li, D.; Xiong, L.; et al.
Small cell lung cancer (SCLC) is an aggressive type of lung cancer. Due to the poor survival rate of SCLC patients, efforts to better understand the mechanisms underlying tumorigenesis and metastasis are sought. Utilizing a SILAC-based quantitative proteomic workflow, Xu and colleagues assessed the molecular mechanisms of SCLC metastasis by investigating the highly expressed ADAM12S protein in SCLC cells. In combining experimental and bioinformatic results, this discovery work revealed the correlation of ADAM12S to glycolysis and metabolic reprogramming. In addition to furthering our understanding of the oncogenic functions of ADAM12S, this study helps pave next steps in identifying a therapeutic intervention for SCLC.
Preclinical Studies on Metal-based Anticancer Drugs as Enabled by Integrated Metallomics and Metabolomics
Galvez, L.; Rusz, M.; Schwaiger-Haber, M.; et al.
Oxaliplatin is a chemotherapy drug administered to aid treatment of metastatic colorectal cancer. Despite its regularity, the impact of this metallodrug on drug uptake/distribution and the metabolome remains unclear. In an effort to address this, Koellensperger and colleagues developed an integrated metallomics/metabolomics method for evaluating sensitive/resistant human colon cancer cell models. This approach involved adding a U-13C metabolite yeast extract (ISO1) at the extraction stage for normalization and improved repeatability, with split analysis for platinum (by ICP-MS) and metabolite (by HILIC-MS/MS) measurement. The combined results shed light on oxaliplatin resistance mechanisms, with future studies needed to investigate the effects of inhibiting fatty acid oxidation on drug sensitivity/resistance.
Leucine Co-Ingestion Augments the Muscle Protein Synthetic Response to the Ingestion of 15 g Protein following Resistance Exercise in Older Men
Holwerda, A.M.; Paulussen, K.J.M.; Overkamp, M.; et al.
Anabolic resistance is considered to play a key role in the progression of sarcopenia in older adults. Resistance exercise potently increases muscle protein synthesis, with post-exercise recovery further enhanced by the ingestion of >40 g of protein. Since older individuals may not be able to ingest such large doses of protein, van Loon and colleagues investigated the effect of co-ingesting 15 g of protein with or without added leucine. By combining the ingestion of an intrinsically-labeled protein beverage with an infusion of stable isotope-labeled amino acids, its metabolic impact during post-exercise recovery could be evaluated. The results revealed that co-ingesting a lower amount of protein with free leucine further increases muscle protein synthesis during post-exercise recovery in older adults.
Assessment of Methylcitrate and Methylcitrate-to-Citrate Ratio in Dried Blood Spots as Biomarkers for Inborn Errors of Propionate Metabolism
Al-Dirbashi, O.Y.; Alfadhel, M.; Al-Thihli, K.; et al.
Propionyl-CoA metabolic defects require early diagnosis in neonates to limit life-threatening complications. Regrettably, a specific marker for the prognosis/monitoring of propionic acidemia (PA) has yet to be proposed. Al-Dirbashi et al. therefore aimed to evaluate the potential of methylcitric acid (MCA) and its ratio to citric acid (CA) as markers of propionate metabolism disorders. The method quantified CA and MCA derivatives in patient DBS samples by RPLC-MRM/MS, with D4 CA and D3 MCA functioning as internal standards. Although further studies with larger patient cohorts are required, the novel results demonstrate that MCA and MCA/CA can serve as a potential biomarker for both PA and methylmalonic acidemia.
Metabolomics and Isotope Tracing
Jang, C.; Chen, L.; Rabinowitz, J.D.
Metabolomics and metabolism are two increasingly employed research endeavors. Given the advancements and the complimentary nature of these fields, Rabinowitz and colleagues herein review the analytical workflow (from sample handling to data analysis/interpretation) and best practices for both measuring/quantifying metabolites (in metabolomics) and tracing stable isotope labeling (in metabolism). Highlighted are four types of biological applications, with an eye into future metabolic research directions.