Glycogen Phosphorylase: a Novel Biomarker in Doxorubicin-Induced Cardiac Injury Yueming Zhu1 and David Gius1,2

Published OnlineFirst January 22, 2018; DOI: 10.1158/1078-0432.CCR-17-3276

CCR Translations Clinical Cancer Research Glycogen Phosphorylase: A Novel Biomarker in Doxorubicin-Induced Cardiac Injury Yueming Zhu1 and David Gius1,2

Extracellular vesicles containing glycogen phosphorylase, the chemotherapy-induced tissue damage and augmented with brain/heart (PYGB) have been demonstrated as a sensitive bio- mitochondrial antioxidant could be an effective means of early marker for normal cardiac injuries for patients after chemother- intervention. Clin Cancer Res; 24(7); 1516–7. Ó2018 AACR. apy. Oxidative stress was suggested to be the mechanism behind See related article by Yarana et al., p. 1644

In this issue of Clinical Cancer Research, Yarana and colleagues oxidative and/or metabolic cellular stress. In this regard, normal suggested a new diagnostic molecular biomarker that could cells treated with systemic agents appear to exhibit prolonged potentially be used for the early detection of cardiac injury after elevated reactive oxygen species (ROS) levels, and the increase in chemotherapy in patients with malignancies (1). In this regard, it ROS would inevitably result in the oxidation of many biomole- is very common that, at least in some significant part, therapy for cules, including mitochondrial lipids, protein, and mtDNA, that human malignancies includes the use of systemic therapies, that could consequently lead to organelle dysfunction as well as cell is, chemotherapy. In fact, it is predicted that nearly 20 million death. These results and observations have long led to the idea Americans will be cancer survivors in less than 10 years, empha- that cancer patients undergoing chemotherapy may exhibit an sizing the need for a greater understanding of the causes and increase in oxidative stress–induced normal tissue damage that mechanisms accounting for cell killing and/or cellular damage in eventually leads to normal tissue toxicity, including in the heart normal tissues, such as neuropathy, cardiomyopathy, or cognitive tissue. Therefore, monitoring the current oxidative stress levels, via dysfunction (1). Among those adverse effects, cardiovascular molecular biomarkers for oxidative stress and/or altered cellular disease is the leading cause of long-term toxicity as well as metabolism, in the normal tissue could represent a novel and treatment-related deaths in cancer survivors. However, there is precise method to detecting chemotherapy-induced normal a lack of sensitive and/or predictive molecular biomarkers that tissue injury. address this critical issue in cancer therapy prior to the onset of To validate and subsequently qualify a molecular biological symptoms (2). In this novel and seminal article, it is shown that marker for cardiac damage, there are a few prerequisites, including glycogen phosphorylase, brain/heart (PYGB) may serve as an that the proposed biomarkers need to (i) be easily obtained, (ii) early detectable molecular biomarker for cardiac damage and, as accurately reflect the chemotherapy-induced damage, and (iii) be such, may be very useful as a clinical early intervention tool to relatively stable. It is well-known that cells have a sophisticated protect patients from treatment-induced cardiovascular disease. mechanism to main cellular homeostasis. In this regard, this Multiple studies have shown that systemic agents, such as article suggests that extracellular vesicles (EV) may be a candidate doxorubicin, can cause not only DNA damage but also induce that meets these criteria. As mentioned, Yarana and colleagues cell apoptosis and significantly alter cellular oxidative metabo- hypothesize that the lipid bilayer makes EVs very stable in the lism, and it seems likely that all of these damaging cellular extracellular environment, and human serums contains high processes are mechanistically connected (3). Interestingly, doxo- levels of EVs. The most important reason that EVs may be a rubicin, as well as many other systemic anticancer agents, can potential molecular biomarker for normal tissue cardiomyocyte significantly decrease the cellular antioxidant capacity and dam- damage is that EVs carry origination-specific proteins, lipids, and age the mitochondrial electron transportation efficiency (4). It has other important biomolecules that could reflect the current bio- been proposed that normal cells, including cardiomyocytes, logical conditions of the releasing cells. exhibiting oxidative damage when exposed to doxorubicin Glycogen phosphorylase is one of the phosphorylase enzymes appear to directly induce DNA damage, and this is the process and catalyzes the rate-limiting step in glycogenolysis. Many that connects exposure to metabolic protein dysfunction and studies suggested that glycogen phosphorylases are sensitive biomarkers of myocardial ischemia, acute coronary syndromes, and hypertrophic cardiomyopathy (5). In this study, Yarana 1Department of Radiation Oncology, Northwestern University Feinberg School and colleagues demonstrated that one specific glycogen phos- of Medicine, Chicago, Illinois. 2Department of Pharmacology, Robert Lurie phorylase, PYGB, could be used as a new perspective marker to Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, assess the cardiac injury risk in patients after chemotherapy. Illinois. Yarana and colleagues investigated the protein content of EVs Corresponding Author: David Gius, Northwestern University Feinberg School and found that EVs present after doxorubicin treatment exhibit of Medicine, Room 3119, Lurie Building, Chicago, IL 60611. Phone: 312-503- signatures of cardiac tissue and high levels of protein-bound 2053; E-mail: [email protected] 4-hydroxynonenal (4HNE). Further proteomic profiling data doi: 10.1158/1078-0432.CCR-17-3276 revealed that doxorubicin-treated EVs distinctively contained Ó2018 American Association for Cancer Research. abrain/heart–specific glycogen phosphorylase (PYGB). Their

1516 Clin Cancer Res; 24(7) April 1, 2018

PYGB as a Cardiac Injuries Detection Biomarker

Circulating PYGB EVs 4HNE-adducted Chemo drugs proteins

EVs Figure 1. The scheme of how EVs function as a biomarker for cardiac injury. Chemotherapy caused increased production of ROS in normal heart cells and further lead to persistent oxidative stress. The increased ROS oxidative stress induces oxidative protein, fatty acid, and mtDNA damage. The damaged MnSOD biomolecules will be packed in EVs and secreted into the circulation system, which can be used as a Heart cell sensitive marker for cardiac injury. Chemo, chemotherapy.

data also showed that there is a decrease of PYGB level in heart some studies mentioned that MnSOD may directly participate tissue, but not in brain tissue because doxorubicin treatment in other cellular processes, including cell-cycle checkpoint and could not pass the blood–brain barrier, suggesting this glycogen apoptosis (6). It will also be interesting to investigate whether phosphorylase could be a specific indicator for the doxorubicin- MnSOD, the primary mitochondrial antioxidant, could have a damaged heart tissue. specific role other than superoxide dismutase after chemother- Thus, monitoring PYGB in circulating EVs can accurately apy. Understanding those questions can further improve the ascertain the condition of cells after chemotherapy, which new biological rationale of early detection and intervention for increased 4HNE-adducted EVs with PYGB, representing the high chemotherapy-induced cardiac injuries. oxidative stress status and a possible glycogenolysis dysfunction as well as early sign of cardiac tissue damage (Fig. 1). In Disclosure of Potential Conflicts of Interest addition, mice with MnSOD overexpression or MnP-pretreated No potential conflicts of interest were disclosed. mice exhibited lesser EV release from heart and decreased 4HNE levels as compared with the control group. Interestingly, DRZ, a Authors' Contributions similar antioxidant treatment, also reduced the EV release but fi Conception and design: Y. Zhu, D. Gius with a weaker result. Because MnSOD speci cally catalyzed the Writing, review, and/or revision of the manuscript: Y. Zhu, D. Gius reaction of superoxide to hydrogen peroxides, it will be interesting to see whether future studies can explore the connection Received November 27, 2017; revised January 5, 2018; accepted January 18, between particular ROS with cardiac damage. Furthermore, 2018; published OnlineFirst January 22, 2018.

References 1. Yarana C, Carroll D, Chen J, Chaiswing L, Zhao Y, Noel T, et al. Extracellular 4. Yarana C, St Clair DK. Chemotherapy-induced tissue injury: an insight into vesicles released by cardiomyocytes in a doxorubicin-induced cardiac injury the role of extracellular vesicles-mediated oxidative stress responses. Anti- mouse model contain protein biomarkers of early cardiac injury. Clin oxidants 2017;6:pii:E75. Cancer Res 2018;24:1644–53. 5. Dobric M, Ostojic M, Giga V, Djordjevic-Dikic A, Stepanovic J, Radovanovic 2. Manrique CR, Park M, Tiwari N, Plana JC, Garcia MJ. Diagnostic strategies for N, et al. Glycogen phosphorylase BB in myocardial infarction. Clin Chim early recognition of cancer therapeutics-related cardiac dysfunction. Clin Acta 2015;438:107–11. Med Insights Cardiol 2017;11:1179546817697983. 6. Jin C, Qin L, Shi Y, Candas D, Fan M, Lu CL, et al. CDK4-mediated MnSOD 3. Mitry MA, Edwards JG. Doxorubicin induced heart failure: phenotype and activation and mitochondrial homeostasis in radioadaptive protection. Free molecular mechanisms. Int J Cardiol Heart Vasc 2016;10:17–24. Radic Biol Med 2015;81:77–87.

www.aacrjournals.org Clin Cancer Res; 24(7) April 1, 2018 1517

Glycogen Phosphorylase: A Novel Biomarker in Doxorubicin-Induced Cardiac Injury

Yueming Zhu and David Gius

Clin Cancer Res 2018;24:1516-1517. Published OnlineFirst January 22, 2018.

Updated version Access the most recent version of this article at: doi:10.1158/1078-0432.CCR-17-3276

Cited articles This article cites 6 articles, 1 of which you can access for free at: http://clincancerres.aacrjournals.org/content/24/7/1516.full#ref-list-1

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