| Autor: |
Regan JN; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States., Mikesell C; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States., Reiken S; Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, United States., Xu H; Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States., Marks AR; Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, United States., Mohammad KS; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States., Guise TA; Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States., Waning DL; Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States. |
| Abstrakt: |
Muscle weakness and cachexia are significant paraneoplastic syndromes of many advanced cancers. Osteolytic bone metastases are common in advanced breast cancer and are a major contributor to decreased survival, performance, and quality of life for patients. Pathologic fracture caused by osteolytic cancer in bone (OCIB) leads to a significant (32%) increased risk of death compared to patients without fracture. Since muscle weakness is linked to risk of falls which are a major cause of fracture, we have investigated skeletal muscle response to OCIB. Here, we show that a syngeneic mouse model of OCIB (4T1 mammary tumor cells) leads to cachexia and skeletal muscle weakness associated with oxidation of the ryanodine receptor and calcium (Ca 2+ ) release channel (RyR1). Muscle atrophy follows known pathways via both myostatin signaling and expression of muscle-specific ubiquitin ligases, atrogin-1 and MuRF1. We have identified a mechanism for skeletal muscle weakness due to increased oxidative stress on RyR1 via NAPDH oxidases [NADPH oxidase 2 (Nox2) and NADPH oxidase 4 (Nox4)]. In addition, SMAD3 phosphorylation is higher in muscle from tumor-bearing mice, a critical step in the intracellular signaling pathway that transmits TGFβ signaling to the nucleus. This is the first time that skeletal muscle weakness has been described in a syngeneic model of OCIB and represents a unique model system in which to study cachexia and changes in skeletal muscle. |
