EXTRACELLULAR MATRIX REMODELING AND FIBROSIS DURING THE DEVELOPMENT OF CANCER CACHEXIA

Wesley S. Haynie1, Jacob L. Brown1, David E. Lee1, Megan E. Rosa-Caldwell1, Richard, A. Perry1, Lemuel A. Brown1, Nicholas P. Greene1, Tyrone A. Washington1. 1University of Arkansas, Fayetteville, Arkansas. Cancer-cachexia is the largely irreversible wasting of lean body mass as a result of cancer progression, affecting ~80% of all cancer patients with as much as ~40% of cancer-related deaths being attributed directly to cachexia. Cachexia has been associated with increased fibrosis and reduced physiological function in cardiac muscle, but the possible role and development of fibrosis and associated extracellular matrix (ECM) remodeling in skeletal muscle has lacked evaluation. PURPOSE: To examine the effects of cancer cachexia on ECM remodeling and the development of fibrosis in skeletal muscle. METHODS: 40 C57BL6/J mice were injected with either Lewis Lung Carcinoma cells or a PBS control into their hind-flank at 8 wks of age. The tumor was allowed to develop for 1, 2, 3, or 4 wks (n=8 per group). Tibialis anterior (TA) muscle was extracted and immediately frozen for morphology and mRNA abundance analysis using RT-qPCR. RESULTS: There were no changes in TA muscle weight until 4 wks post-tumor implantation which resulted in a ~22% lower muscle wet weight compared to PBS control (p<0.05). PicroSirius Red staining of TA muscle sections resulted in no change in collagen abundance in all groups with the exception of a 2-3-fold increase at 4 wks relative to all other groups (p<0.05). Collagen 1 mRNA abundance was ~50 % and ~60 % lower than control at 3 and 4 wks post tumor injection, respectively (p<0.05). Collagen 1 mRNA abundance was ~2-fold higher at 1 and 2 wks but there was no difference at 3 or 4wks, all relative to control (p<0.05). The ratio of Collagen 3:1 mRNA abundance decreased ~30-50% from 1-3wks compared to control (p<0.05), but there was no difference at 4-wks. MMP-2 mRNA abundance was ~50% higher at 1-wk compared to control (p<0.05), but was not different 2-4wks from control (p<0.05). MMP-9 mRNA abundance was 3 and 6-fold greater than control at 3 and 4-wks post-injection, respectively (p<0.05). There was a main effect of tumor implantation to reduce TIMP-1 mRNA abundance ~20-70% (p<0.05). CONCLUSION: The development of cancer cachexia results in dysregulation of ECM remodeling and increased collagen deposition within skeletal muscle. This dysregulation could negatively affect skeletal muscle’s ability to maintain muscle mass and respond to other environmental stressors. ACKNOWLEDGEMENTS: This study was funded by the National Institutes of Health, Award number: R15 AR069913/AR/NIAMS.