Background
Intramyocellular lipids are an important source of fuel for mitochondrial fat oxidation and play an important role in intramuscular lipid homeostasis. We hypothesised that due to the phenotype associated with cancer cachexia, there would exist an association between increasing weight loss and the number/size of intramyocellular lipid droplets.
Methods
Nineteen cancer patients and 6 controls undergoing surgery were recruited. A rectus abdominis biopsy was performed and processed for transmission electron microscopy (TEM). The number of intramyocellular lipid droplets and lipid droplet diameter were calculated from the TEM images. CT scans, performed as part of patients' routine care, were analysed to determine amount of adipose (intermuscular, visceral and subcutaneous) and muscle tissue.
Results
Compared with controls, cancer patients had increased numbers of lipid droplets (mean (SD) 1.8 (1.9) vs. 6.4 (9.1) per Γ2,650 field, respectively, pβ=β0.036). Mean (SD) lipid droplet diameter was also higher in cancer patients compared with controls (0.42 (0.13) vs. 0.24 (0.21) ΞΌm, pβ=β0.015). Mean lipid droplet count correlated positively with the severity of weight loss (Rβ=β0.51, pβ=β0.025) and negatively with CT-derived measures of intermuscular fat (Rβ=ββ0.53, pβ=β0.022) and visceral fat (Rβ=ββ0.51, pβ=β0.029).
Conclusions
This study suggests that the number and size of intramyocellular lipid droplets is increased in the presence of cancer and increases further with weight loss/loss of adipose mass in other body compartments.