Increased myocellular lipid and IGFBP‐3 expression in a pre‐clinical model of pancreatic cancer‐related skeletal muscle wasting

Abstract

Background Skeletal muscle wasting (SMW) in cancer patients is associated with increased morbidity, mortality, treatment intolerance and discontinuation, and poor quality of life. This is particularly true for patients with pancreatic ductal adenocarcinoma (PDAC), as over 85% experience SMW, which is responsible for ~30% of patient deaths. While the established paradigm to explain SMW posits that muscle catabolism from systemic inflammation and nutritional deficiencies, the cause of death, and the cellular and molecular mechanisms responsible remain to be elucidated. To address this, we investigated the relationship between tumour burden and survival in the KCKO murine PDAC model. Methods Female C57BL/6J mice 6–8 weeks of age underwent orthotopic injection with KCKO‐luc tumour cells. Solid tumour was verified on Day 5, post‐tumour inoculation. In vivo, longitudinal lean mass and tumour burden were assessed via dual‐energy X‐ray absorptiometry and IVIS imaging, respectively, and total body weight was assessed, weekly. Animals were sacrificed at a designated end point of ‘failure to thrive’. After sacrifice, lower limb hind muscles were harvested for histology and RNA extraction. Results We found a strong correlation between primary tumour size and survival (r2 = 0.83, P < 0.0001). A significant decrease in lower limb lean mass was first detected at Day 38 post‐implantation vs. no tumour controls (NTCs) (P < 0.0001). SMW was confirmed by histology, which demonstrated a 38%, 32.7%, and 39.9% decrease in fibre size of extensor digitorum longus, soleus, and tibialis anterior muscles, respectively, in PDAC mice vs. NTC (P < 0.002). Histology also revealed a 67.6% increase in haematopoietic cells within the muscle of PDAC mice when compared with NTC. Bulk RNAseq on muscles from PDAC mice vs. NTC revealed significant increases in c/ebpβ/Δ, il‐1, il‐6, and tnf gene expression. Pathway analyses to identify potential upstream factors revealed increased adipogenic gene expression, including a four‐fold increase in igfbp‐3. Histomorphometry of Oil Red‐O staining for fat content in tibialis anterior muscles demonstrated a 95.5% increase in positively stained fibres from PDAC mice vs. NTC. Conclusions Together, these findings support a novel model of PDAC‐associated SMW and mortality in which systemic inflammation leads to inflammatory cell infiltration into skeletal muscle with up‐regulated myocellular lipids.

Role of Glucocorticoid Signaling and HDAC4 Activation in Diaphragm and Gastrocnemius Proteolytic Activity in Septic Rats

“…Several data suggest that IGFBP-3 plays an important role in human pancreatic cancer-induced cachexia [ 54 , 55 ]. An increase in muscle IGFBP-3 has also been observed in cachexia induced by experimental models of arthritis and cancer [ 56 , 57 ]. One of the mechanisms by which IGFBP-3 induces muscle wasting seems to be due to an increase in ubiquitin-proteasome proteolysis activity [ 54 ].…”

IGFBP-3 promotes cachexia-associated lipid loss by suppressing insulin-like growth factor/insulin signaling

“…This model was associated with systemic inflammatory reaction which has great value in digestive system cancer treatment. [48] Notably, the effects of IGFBP-3 in adipose tissue were recapitulated in an evolutionarily conserved Drosophila model, in which malignant yki-gut tumors caused abdomen bloating, lipid loss, and hyperglycemia in the fly via production of ImpL2, an established IGFBP-3 homolog. ImpL2 blocks the dissemination of IGF-like peptides in the blood, blocks the IGF/insulin pathway in adipose and muscle, and decreases protein synthesis in adipose and muscle, thus leading to fat loss and muscle dysfunction.…”

“…This model was associated with systemic inflammatory reaction which has great value in digestive system cancer treatment. [48]…”

Activated Oncostatin M signaling drives cancer-associated skeletal muscle wasting

“…Igfbp3 encodes an IGF-binding protein, which was shown to suppress IGF signaling and promote atrophy in C2C12 myotubes (Huang et al, 2016). Increased Igfbp3 levels were detected in muscles of tumor-bearing mice (Cole et al, 2021). Cebpd (CAAT/enhancer-binding protein δ) expression was induced in atrophying muscles of glucocorticoid-treated and tumor-bearing mice (Fontes-Oliveira et al, 2014; Yang et al, 2005).…”