{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T08:39:38Z","timestamp":1785400778834,"version":"3.56.0"},"posted":{"date-parts":[[2026,7,13]]},"group-title":"Biochemistry","reference-count":40,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T00:00:00Z","timestamp":1783900800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"id":[{"id":"https:\/\/ror.org\/0593mby10","id-type":"ROR","asserted-by":"publisher"}]},{"id":[{"id":"https:\/\/ror.org\/048e7gn38","id-type":"ROR","asserted-by":"publisher"}]},{"id":[{"id":"https:\/\/ror.org\/05xs6nw18","id-type":"ROR","asserted-by":"publisher"}]},{"name":"The Orion Research Foundation"},{"name":"The Ida Montin Foundation"},{"DOI":"10.13039\/100020581","name":"Fondazione AIRC","doi-asserted-by":"crossref","award":["IG 2024-ID. 31126"],"award-info":[{"award-number":["IG 2024-ID. 31126"]}],"id":[{"id":"10.13039\/100020581","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Department of Pathology and Cancer Center at University of Colorado Anschutz"},{"name":"NIH\/NIAMS","award":["R01AR079379, R01AR080051"],"award-info":[{"award-number":["R01AR079379, R01AR080051"]}]},{"name":"Wings of Hope for Pancreatic Cancer Research"},{"name":"the Cancer Foundation Finland"},{"DOI":"10.13039\/501100002341","name":"Research Council of Finland","doi-asserted-by":"crossref","award":["Profi6 funding (336449)"],"award-info":[{"award-number":["Profi6 funding (336449)"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,7,13]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>\n                    Aberrant NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism has been implicated in the pathogenesis of cancer cachexia, highlighting this pathway as a potential therapeutic target to mitigate skeletal muscle wasting. However, it remains unclear whether chemotherapeutic agents contribute to the onset of cachexia by disrupting NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism. Here, we investigated the effects of commonly used chemotherapy regimens on NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism in skeletal muscle and liver of healthy mice.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>\n                    Healthy mice were treated with either 2-week regimens of folfiri or cisplatin, or 5-week regimens of folfiri or folfox, with vehicle-treated mice serving as controls. Cachexia-related outcomes were assessed, while skeletal muscle and liver tissues were analyzed for NAD metabolites and markers of NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism. Given the consistent downregulation of the NAD\n                    <jats:sup>+<\/jats:sup>\n                    biosynthetic enzyme\n                    <jats:italic>Nrk2<\/jats:italic>\n                    in cachectic chemotherapy-treated mice, we examined skeletal muscle\n                    <jats:italic>Nrk2<\/jats:italic>\n                    \/\n                    <jats:italic>NRK2<\/jats:italic>\n                    expression across published murine and human cachexia datasets, and in additional models of muscle wasting and hypertrophy.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>\n                    NAD\n                    <jats:sup>+<\/jats:sup>\n                    loss was observed in atrophic muscle following administration of cisplatin (2-week treatment; \u221214% vs controls, p=0.047) and folfiri (5-week treatment; \u221218%, p=0.069). In contrast, muscle NAD\n                    <jats:sup>+<\/jats:sup>\n                    levels were preserved in non-atrophic groups (2-week folfiri and 5-week folfox). Muscle\n                    <jats:italic>Nrk2<\/jats:italic>\n                    was the most responsive NAD\n                    <jats:sup>+<\/jats:sup>\n                    biosynthetic enzyme, showing consistent downregulation across chemotherapy models with ongoing or developing muscle loss: cisplatin (\u221293%, p&lt;0.001), folfiri (\u221284%, p&lt;0.001) and folfox (\u221292%, p&lt;0.001). In the liver, NAD\n                    <jats:sup>+<\/jats:sup>\n                    levels declined after prolonged 5-week folfiri (\u221220%, p=0.013) and folfox (\u221215%, p=0.043) treatments. These changes were accompanied by distinct alterations in NAD\n                    <jats:sup>+<\/jats:sup>\n                    biosynthesis pathways, indicating treatment-specific reorganization of hepatic NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism. Cross-study analyses revealed early and consistent skeletal muscle\n                    <jats:italic>Nrk2<\/jats:italic>\n                    downregulation across multiple murine cachexia models and human inactivity studies, whereas cachexia-targeted interventions in rodents and resistance training in humans increased its expression.\n                  <\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>\n                    These findings demonstrate that chemotherapy distrupts tissue NAD\n                    <jats:sup>+<\/jats:sup>\n                    metabolism, with skeletal muscle NAD\n                    <jats:sup>+<\/jats:sup>\n                    loss accompanying muscle atrophy and hepatic NAD\n                    <jats:sup>+<\/jats:sup>\n                    levels declining after prolonged treatment. The early and robust responsiveness of muscle\n                    <jats:italic>Nrk2<\/jats:italic>\n                    expression to changes in muscle mass underscores its potential as a dynamic indicator for predicting treatment-induced changes in muscle mass. Together, these results provide new molecular insight into the metabolic basis of chemotherapy-induced muscle wasting and support further investigation of NAD\n                    <jats:sup>+<\/jats:sup>\n                    -targeted strategies in this context.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.07.11.736679","type":"posted-content","created":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T16:30:17Z","timestamp":1783960217000},"source":"Crossref","is-referenced-by-count":0,"title":["Chemotherapy induces tissue NAD\n                  <sup>+<\/sup>\n                  loss, and downregulation of NAD\n                  <sup>+<\/sup>\n                  biosynthetic enzyme\n                  <i>Nrk2<\/i>\n                  marks muscle wasting"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3295-1260","authenticated-orcid":false,"given":"Noora","family":"P\u00f6ll\u00e4nen","sequence":"first","affiliation":[{"name":"Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-1659-1261","authenticated-orcid":false,"given":"Caleb J.","family":"Gammon","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Colorado Anschutz, Aurora, CO 80045 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3562-8629","authenticated-orcid":false,"given":"Fabrizio","family":"Pin","sequence":"additional","affiliation":[{"name":"Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN 46202 USA"},{"name":"Simon Comprehensive Cancer Center, Indianapolis, IN 46202 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8632-5791","authenticated-orcid":false,"given":"Joshua R.","family":"Huot","sequence":"additional","affiliation":[{"name":"Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN 46202 USA"},{"name":"Simon Comprehensive Cancer Center, Indianapolis, IN 46202 USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2763-9838","authenticated-orcid":false,"given":"Roberta","family":"Sartori","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, University of Padova, Padova, Italy."},{"name":"Veneto Institute of Molecular Medicine, Padova, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2774-6027","authenticated-orcid":false,"given":"Fabio","family":"Penna","sequence":"additional","affiliation":[{"name":"Experimental Medicine and Clinical Pathology Unit, Department of Clinical and Biological Sciences, University of Torino, Turin, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3813-2124","authenticated-orcid":false,"given":"Juha","family":"Hulmi","sequence":"additional","affiliation":[{"name":"Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyv\u00e4skyl\u00e4, Jyv\u00e4skyl\u00e4, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3235-1871","authenticated-orcid":false,"given":"Andrea","family":"Bonetto","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Colorado Anschutz, Aurora, CO 80045 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