Effects of Sulindac on Inflammatory and Cellular Responses in Mammary Tumors from Obese Mice
Creators: name: Cody, Morgan
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2022

description: Purpose: To investigate the mechanisms underlying sulindac remediation of obesity mediated exacerbation of E0771 mammary tumor growth.

Background: Breast cancer is the second leading cause of cancer-related death in U.S. women. Obesity (BMI > 30 kg/m2) promotes breast cancer incidence, progression, and mortality in women of all ages. The prevalence of obesity in the U.S. has increased dramatically over recent decades and continues to rise. Although obesity is associated with increased adipose tissue inflammation and metabolic dysfunction, the exact mechanisms regulating obesity exacerbated tumor growth are relatively unknown. Non-steroidal anti-inflammatory drugs (NSAIDs), like sulindac, inhibit cyclooxygenase-1 and/or  cyclooxygenase-2 which consequently modulates the secretion of pro-inflammatory cytokines. Hence, we sought to investigate whether sulindac may delay mammary tumor progression in obese mice. 

Methods:
C57BL/6J mice were fed either a high-fat diet (n=36) or a low-fat control diet (n=40) for 15 weeks. Half of the control (n=20) and DIO (n=19) mice were then treated with 140 ppm sulindac in their respective diets for four weeks prior to orthotopic injection of 20,000 E0771 cells. Tumors were harvested and weighed, and serum was collected four weeks following injection. Bulk transcriptional profile analysis was performed on the tumors using Affymetrix microarray and subsequent gene set enrichment analysis (GSEA) to identify significantly enriched gene sets in E0771 tumors from DIO mice relative to sulindac treated DIO and control mice. Serum cytokine levels were measured using the Bio-Plex Pro 33-plex mouse chemokine panel and multiple linear regression was conducted to identify cytokines significantly associated with mammary tumor size independent of diet or treatment.

Results:
DIO mice had increased tumor weight relative to control mice, while sulindac decreased tumor weight in DIO but not control mice. GSEA analysis revealed only one gene set upregulated in the DIO group relative to control or DIO sulindac tumors. Immune related gene sets were commonly enriched in tumors from control and DIO sulindac relative to DIO mice, suggesting that sulindac restored markers of tumor immunosurveillance in tumors from DIO mice. Leading edge analysis of the significantly enriched gene sets showed that the reversal of DIO mediated immunosuppression by sulindac occurred via principally overlapping genes. Leading edge analysis revealed that cytokine and immune genes predominate sulindac remediation of DIO genes. Sulindac modified circulating serum cytokine levels, but multiple linear regression revealed that cytokine levels were not independently predictive of tumor weight. 

Conclusions: 
This Honors thesis work suggests that sulindac can reverse transcriptional changes in obese mammary tumors and restore immunosurveillance. Sulindac, and potentially other NSAIDs, may be able to protect against obesity driven mammary tumor growth via remodeling of antitumor immune function.