diagnostics Article The ERG1A K + Channel Is More Abundant in Rectus abdominis Muscle from Cancer Patients Than that from Healthy Humans Sandra Zampieri 1,2 , Marco Sandri 2 , Joseph L. Cheatwood 3 , Rajesh P. Balaraman 4 , Luke B. Anderson 3 , Brittan A. Cobb 3 , Chase D. Latour 5 , Gregory H. Hockerman 6 , Helmut Kern 7 , Roberta Sartori 2 , Barbara Ravara 1 , Stefano Merigliano 1 , Gianfranco Da Dalt 1 , Judith K. Davie 8 , Punit Kohli 4 and Amber L. Pond 3, *   Citation: Zampieri, S.; Sandri, M.; Cheatwood, J.L.; Balaraman, R.P.; Anderson, L.B.; Cobb, B.A.; Latour, C.D.; Hockerman, G.H.; Kern, H.; Sartori, R.; et al. The ERG1A K + Channel Is More Abundant in Rectus abdominis Muscle from Cancer Patients Than that from Healthy Humans. Diagnostics 2021, 11, 1879. https://doi.org/10.3390/diagnostics 11101879 Academic Editor: Antonio Maccio Received: 27 August 2021 Accepted: 8 October 2021 Published: 12 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Departmentof Surgery, Oncology and Gastroenterology, University of Padova, 35122 Padova, Italy; sanzamp@unipd.it (S.Z.); barbara.ravara@unipd.it (B.R.); stefano.merigliano@unipd.it (S.M.); gianfdada@gmail.com (G.D.D.) 2 Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; marco.sandri@unipd.it (M.S.); roberta.sartori@unipd.it (R.S.) 3 Anatomy Department, Southern Illinois University School of Medicine, Carbondale, IL 62902, USA; jcheatwood@siumed.edu (J.L.C.); lukebriananderson@gmail.com (L.B.A.); brittan.a.cobb@gmail.com (B.A.C.) 4 Department of Chemistry and Biochemistry, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA; rpb016@shsu.edu (R.P.B.); pkohli@chem.siu.edu (P.K.) 5 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; cdlatour@live.unc.edu 6 Medicinal Chemistry and Molecular Pharmacology Department, Purdue University School of Pharmacy, West Lafayette, IN 47906, USA; gregh@purdue.edu 7 Physiko-und Rheumatherapie GmbH, 3100 St. Poelten, Austria; helmut@kern-reha.at 8 Biochemistry Department, Southern Illinois University School of Medicine, Carbondale, IL 62902, USA; jdavie@siumed.edu * Correspondence: apond@siumed.edu Abstract: Background: The potassium channel encoded by the ether-a-gogo-related gene 1A (erg1a) has been detected in the atrophying skeletal muscle of mice experiencing either muscle disuse or cancer cachexia and further evidenced to contribute to muscle deterioration by enhancing ubiquitin proteolysis; however, to our knowledge, ERG1A has not been reported in human skeletal muscle. Methods and Results: Here, using immunohistochemistry, we detect ERG1A immunofluorescence in human Rectus abdominis skeletal muscle sarcolemma. Further, using single point brightness data, we report the detection of ERG1A immunofluorescence at low levels in the Rectus abdominis muscle sarcolemma of young adult humans and show that it trends toward greater levels (10.6%) in healthy aged adults. Interestingly, we detect ERG1A immunofluorescence at a statistically greater level (53.6%; p < 0.05) in the skeletal muscle of older cancer patients than in age-matched healthy adults. Importantly, using immunoblot, we reveal that lower mass ERG1A protein is 61.5% (p < 0.05) more abundant in the skeletal muscle of cachectic older adults than in healthy age-matched controls. Additionally, we report that the ERG1A protein is detected in a cultured human rhabdomyosarcoma line that may be a good in vitro model for the study of ERG1A in muscle. Conclusions: The data demonstrate that ERG1A is detected more abundantly in the atrophied skeletal muscle of cancer patients, suggesting it may be related to muscle loss in humans as it has been shown to be in mice experiencing muscle atrophy as a result of malignant tumors. Keywords: erg1a; potassium channel; dystrophin; sarcolemma membrane; cachexia; rhabdomyosarcoma 1. Introduction Skeletal muscle atrophy is defined as a decrease in muscle contractile proteins that implies a weakening of strength. Atrophy occurs with normal aging and can also result from muscle disuse as well as muscle and/or neural damage or disease [1–4]. Age-related Diagnostics 2021, 11, 1879. https://doi.org/10.3390/diagnostics11101879 https://www.mdpi.com/journal/diagnostics