Higher IL-6 peri-tumoural expression is associated with gastro-intestinal neuroendocrine tumour progression

An association of well-differentiated gastroenteropancreatic neuroendocrine tumours (WD GEP NETs) with metabolic syndrome (MetS) was recently described. Yet no molecular mechanisms linking the two conditions are known. This study's aim was to identify putative molecular signatures linking WD GEP NETs and MetS to gain further insight into potential mechanisms for this association. Patients with WD GEP NETs (n=39), pancreatic (panNET) and gastro-intestinal (GI-NET), were clinically evaluated for presence of MetS. WD GEP NETs immunohistochemistry staining for Forkhead box protein M1 (FOXM1), insulin growth factor 1 receptor (IGF1R), Ki-67 and interleukin 6 (IL-6) was performed and quantified by computerised morphometric analysis. FOXM1, Ki-67, IGF1R or IL-6 expression in WD GEP NETs was not influenced by the presence of MetS. IL-6 peritumoural expression was higher in GI-NETs of patients with low HDL cholesterol (0.018±0.005% vs 0.030±0.005%, p=0.02). In GI-NETs, a higher IL-6 expression was also associated with disease progression (0.026±0.004% vs 0.016±0.002%, p=0.03). In WD GEP-NETs, MetS did not influence FOXM1, IGF1R and IL-6 expression. In GI-NETs, IL-6 expression was influenced by the MetS feature low HDL, and positively associated with disease progression. These data suggest that local and systemic inflammatory status can potentially modulate GI-NET behaviour.