Physical Activity Decreases Inflammation and Delays the Development of Obesity-Associated Pancreatic Ductal Adenocarcinoma.

Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), a deadly disease with limited preventive strategies. Lifestyle interventions to decrease obesity represent a potential approach to prevent obesity-associated PDAC. In this study, we examined whether decreasing obesity through physical activity (PA) and/or dietary changes could decrease inflammation in humans and prevent obesity-associated PDAC in mice. Comparison of circulating inflammatory-associated cytokines in subjects (overweight and obese) before and after a PA intervention revealed PA lowered systemic inflammatory cytokines. Mice with pancreatic-specific inducible KrasG12D expression were exposed to PA and/or dietary interventions during and after obesity-associated cancer initiation. In mice with concurrent diet-induced obesity and KrasG12D expression, the PA intervention led to lower weight gain, suppressed systemic inflammation, delayed tumor progression, and decreased proinflammatory signals in the adipose tissue. However, these benefits were not as evident when obesity preceded pancreatic KrasG12D expression. Combining PA with diet-induced weight loss (DI-WL) delayed obesity-associated PDAC progression in the genetically engineered mouse model, but neither PA alone nor combined with DI-WL or chemotherapy prevented PDAC tumor growth in orthotopic PDAC models regardless of obesity status. PA led to the upregulation of Il15ra in adipose tissue. Adipose-specific overexpression of Il15 slowed PDAC growth but only in nonobese mice. Overall, our study suggests that PA alone or combined with DI-WL can reduce inflammation and delay obesity-associated PDAC development or progression. Lifestyle interventions that prevent or manage obesity or therapies that target weight loss-related molecular pathways could prevent progression of PDAC. Significance: Physical activity reduces inflammation and induces changes to adipose-related signaling to suppress pancreatic cancer, supporting the potential of obesity management strategies to reduce the risk of developing pancreatic cancer. See related commentary by Sogunro and Muzumdar, p. 2935.

Physical Activity Delays Obesity-Associated Pancreatic Ductal Adenocarcinoma in Mice and Decreases Inflammation.

BACKGROUND & AIMS: Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), a deadly disease with limited preventive strategies. Lifestyle interventions to decrease obesity might prevent obesity-associated PDAC. Here, we examined whether decreasing obesity by increased physical activity (PA) and/or dietary changes would decrease inflammation in humans and prevent PDAC in mice. METHODS: Circulating inflammatory-associated cytokines of overweight and obese subjects before and after a PA intervention were compared. PDAC pre-clinical models were exposed to PA and/or dietary interventions after obesity-associated cancer initiation. Body composition, tumor progression, growth, fibrosis, inflammation, and transcriptomic changes in the adipose tissue were evaluated. RESULTS: PA decreased the levels of systemic inflammatory cytokines in overweight and obese subjects. PDAC mice on a diet-induced obesity (DIO) and PA intervention, had delayed weight gain, decreased systemic inflammation, lower grade pancreatic intraepithelial neoplasia lesions, reduced PDAC incidence, and increased anti-inflammatory signals in the adipose tissue compared to controls. PA had additional cancer prevention benefits when combined with a non-obesogenic diet after DIO. However, weight loss through PA alone or combined with a dietary intervention did not prevent tumor growth in an orthotopic PDAC model. Adipose-specific targeting of interleukin (IL)-15, an anti-inflammatory cytokine induced by PA in the adipose tissue, slowed PDAC growth. CONCLUSIONS: PA alone or combined with diet-induced weight loss delayed the progression of PDAC and reduced systemic and adipose inflammatory signals. Therefore, obesity management via dietary interventions and/or PA, or modulating weight loss related pathways could prevent obesity-associated PDAC in high-risk obese individuals.

Delayed Processing of Secretin-Induced Pancreas Fluid Influences the Quality and Integrity of Proteins and Nucleic Acids.

OBJECTIVES: Endoscopic pancreatic function tests are used to diagnose pancreatic diseases and are a viable source for the discovery of biomarkers to better characterize pancreatic disorders. However, pancreatic fluid (PF) contains active enzymes that degrade biomolecules. Therefore, we tested how preservation methods and time to storage influence the integrity and quality of proteins and nucleic acids. METHODS: We obtained PF from 9 subjects who underwent an endoscopic pancreatic function test. Samples were snap frozen at the time of collection; after 1, 2, and 4 hours on ice; or after storage overnight at 4°C with or without RNase or protease inhibitors (PIs). Electrophoresis and mass spectrometry analysis determined protein abundance and quality, whereas nucleic acid integrity values determined DNA and RNA degradation. RESULTS: Protein degradation increased after 4 hours on ice and DNA degradation after 2 hours on ice. Adding PIs delayed degradation. RNA was significantly degraded under all conditions compared with the snap frozen samples. Isolated RNA from PF-derived exosomes exhibited similar poor quality as RNA isolated from matched PF samples. CONCLUSIONS: Adding PIs immediately after collecting PF and processing the fluid within 4 hours of collection maintains the protein and nucleic acid integrity for use in downstream molecular analyses.