Osteolytic Breast Cancer Causes Skeletal Muscle Weakness in an Immunocompetent Syngeneic Mouse Model

作者：Jenna N. Regan, Carter Mikesell, Steven Reiken, Haifang Xu, Andrew R. Marks, Khalid S. Mohammad, Theresa A. Guise, David L. Waning · 发表于：Frontiers in Endocrinology · 年份：2017 · DOI：10.3389/fendo.2017.00358 · 被引用次数：36 · 研究领域：Muscle Physiology and Disorders、Cancer, Hypoxia, and Metabolism、Neurogenetic and Muscular Disorders Research

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 (Ca2+) 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 (Nox2 and Nox4). In addition, SMAD3 phosphorylation is higher in muscle from tumor-bearing mice, a critical step in the intracellular signaling pathway that transmits TGF 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.