Interleukin‐8 is Released from Human Pancreatic Tumor and Stromal Cells, and Causative in Skeletal Muscle Atrophy

Abstract

Cancer cachexia is a debilitating metabolic disorder characterized by loss of body weight, muscle mass, and functional deterioration that negatively affects patient's quality of life. Cachexia is particularly prevalent in patients with pancreatic cancer; present in more than 60% of patients at time of diagnosis and more than 80% of advanced stage patients. Initiating factors of cancer cachexia are tumor‐derived, at least in part, yet our understanding of the specific factors is still far from complete. Given that cancer cells collaborate in the tumor microenvironment with tumor associated stromal cells, we collected conditioned media (CM) from primary human pancreatic cancer (PhPC) cells, primary pancreatic tumor associated stromal (PPTAS) cells, and their co‐culture and measured selected cytokines and chemokines using multiple analyte profiling. Amongst all factors measured in PhPC/PPTAS co‐culture CM, Interleukin‐8 (IL‐8/CXCL8) was the highest at 6,071 pg/ml. IL‐8 levels in PhPC CM and PPTAS CM were 625 pg/ml and 71 pg/m, respectively. Thus, there is a synergistic increase in IL‐8 secretion when human pancreatic cancer and stromal cells communicate physically and/or biochemically. To determine the extent to which IL‐8 may cause muscle atrophy we treated differentiated C2C12 myotubes or human myotubes with recombinant IL‐8 (rIL‐8) for 48 hours, which caused a 28% and 25% reduction in myotube diameter, respectively. To test whether PhPC cell CM induces myotube atrophy via IL‐8 signaling we treated C2C12 myotubes with PhPC CM, with or without IL‐8 neutralization or inhibition of the IL‐8 receptor, CXCR2. Myotube diameter was significantly decreased 29% in PhPC CM treated myotubes, but this was significantly attenuated with IL‐8 neutralization and completely abolished by CXCR2 inhibition. To determine whether IL‐8 can lead to muscle wasting in vivo, we injected 50mg/kg of rIL‐8 i.p. into mice every other day for 6 days. This increased serum IL‐8 levels and caused a reduction in body weight (−11%), tibialis anterior (TA) weight (−17%), tricep surae weight (−15%), and gonadal fat weight (−34%). Furthermore, the mean muscle fiber cross sectional area of the TA was also significantly decreased and microarray analysis on these muscles identified ubiquitin ligase complex and oxidative phosphorylation as two of the most enriched biological processes among upregulated and downregulated genes, respectively. These findings identify IL‐8 as a chemokine released from human pancreatic cancer and stromal cells that is sufficient to cause myotube atrophy, and as an active factor causative in myotube atrophy by PhPC CM that is sufficient to induce a cachexia phenotype in vivo.Support or Funding InformationThis work was supported by a Florida Department of Health, Biomedical Research Program Grant, 7BC02 (to A.R.J). C.C.C. and R.L.N. are supported by NIH, NICHD, T32HD043730.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.