Expression of intercellular adhesion molecule-1 (ICAM-1) and its ligand, leukocyte function antigen-1 (LFA-1), after pancreatic islet transplantation may affect both nonspecific and alloantigen-specific phases of graft destruction. We examined the effects of ICAM-1/LFA-1 blockade on the survival of islet allografts. Fresh C57BL/10 (H2h) pancreatic islets were transplanted under the renal subcapsular space (KC) or embolized into the liver after portal vein (PV) injection to C3H (H2k) mice. Recipients remained untreated or were treated for 7 days by i.p. administration of: ICAM-1 antisense phosphorothioate oligodeoxynucleotide (oligo) alone; anti-1CAM-1 (alphaICAM-1) monoclonal antibody (mAb) alone: alphaLFA-1 mAb alone; ICAM-1 oligo/alphaLFA mAb combination; alphaICAM-1 mAb/alphaLFA-1 mAb combination; or control oligo IP-8997 or IP-1082. In some experiments, donors were pretreated with ICAM-1 oligo. Inhibition of single ligand with 5.0 mg/kg ICAM-1 oligo (25.1 +/- 10.3), 100 microg/daily alphaICAM-1 mAb (24.2 +/- 8.0 days), or 50 microg/daily alphaLFA-1 mAb (42.8 +/- 25.9 days) prolonged the survivals of KC islet allografts in comparison with untreated controls (11.9 +/- 1.0 days; all p < 0.01). However, dual ICAM-1/LFA-1 blockade with either ICAM-1 oligo/alphaLFA-1 mAb (78.3 +/- 16.5 days) or (alphaICAM-1 mAb/aLFA-1 mAb (65.2 +/- 31.3 days) was the most effective therapy. Although pretreatment of donors with ICAM-1 oligo alone was ineffective (12.2 +/- 0.8 days; NS), a combination of donor pretreatment and recipient treatment started 1 day prior to grafting with ICAM-1 oligo (39.2 +/- 14.0 days) was more effective than the recipient treatment alone (24.6 +/- 8.8 days). Furthermore, ICAM-1/LFA-1 blockade improved islet function as evaluated by glucose tolerance test, and decreased inflammation in comparison with untreated controls. Similar in vivo results were obtained following PV administration of islet allografts. Thus, ICAM-1/LFA-1 blockade prolongs the survival of pancreatic islet allografts and improves their early function.

Purpose: The objective of this study is to determine the impact of exposure to obesity-related systemic factors on fatty acid synthase enzyme (FASN) expression in breast cancer cells. Methods: MCF-7 breast cancer cells were exposed to sera from patients having obesity or not having obesity and subjected to quantitative reverse transcription polymerase chain reaction (RT-qPCR). Subsequent MTT and colony-forming assays using both MCF-7 and T-47D cells exposed to sera and treated with or without FASN inhibitor, TVB-3166, were used. MCF-7 cells were then treated with insulin and the sterol regulatory element–binding protein (SREBP) processing inhibitor, betulin, prior to analysis of FASN expression by quantitative RT-qPCR and western blot. Insulin-induced SREBP-FASN promoter binding was analyzed by chromatin immunoprecipitation with an anti-SREBP antibody. Results: In response to sera exposure (body mass index [BMI] >30) there was an increase in FASN expression in breast cancer cells. Furthermore, treatment with the FASN inhibitor, TVB-3166, resulted in a decreased breast cancer cell survival and proliferation while increasing apoptosis upon sera exposure (BMI >30). Insulin-exposed MCF-7 cells exhibited an increased FASN messenger RNA and protein expression, which is abrogated upon SREBP inhibition. In addition, insulin exposure induced enhanced SREBP binding to the FASN promoter. Conclusions: Our results implicate FASN as a potential mediator of obesity-induced breast cancer aggression and a therapeutic target of patients with obesity-induced breast cancer.

INTRODUCTION: Breast cancer accounts for nearly 40,000 deaths annually with the overall prognosis worsened if the patient is obese. Reprogramming of lipid metabolism in cancer is an established hallmark and contributes to tumorigenesis and drug-resistance. The fatty acid synthase enzyme (FASN) is overexpressed in multiple solid and hematopoietic tumors and its expression is associated with tumor grade as well as resistance to therapy. Targeted therapies against the fatty acid synthase enzyme (FASN) are currently in phase II of clinical trials for the treatment of multiple solid tumors. Previously, our lab has shown enhanced expression of FASN in breast cancer cells exposed to obese sera as well as increased sensitivity to the FASN inhibitor, TVB-3166. The obese phenotype is characterized by increased circulating bioactive growth factors and hormones, such as insulin, estrogen, and insulin-like growth factor 1 (IGF-1), that are ligands for the insulin (IR) and insulin-like growth factor receptor-1 (IGF-1R). Activation of these receptors can lead to downstream signaling through the PI3K-Akt-mTOR pathway that mediates lipogenic gene expression through various transcription factors. Of these transcription factors, sterol regulatory element-binding protein-1 (SREBP-1), drives FASN gene expression and is activated downstream of both Akt and mTORC1. HYPOTHESIS: We hypothesize that obesity-induced breast cancer progression is mediated through an SREBP dependent overexpression of FASN. METHODS: MCF-7 cells were exposed to obese or non-obese sera and subjected to quantitative RT-PCR for FASN expression. MTT and colony-forming assays using both MCF-7 and T-47D breast cancer cells conditioned in 2% obese and 2% non-obese sera as well as treated with and without a FASN inhibitor (TVB-3166) were utilized to determine cell survival and viability in response to FASN inhibition. FASN expression in obesity-induced breast cancer was investigated by treating MCF-7 cells with either insulin or SREBP processing inhibitor (Betulin) and subjected to chIP-qPCR against anti-SREBP or normal rabbit IgG. RESULTS: In response to obese sera exposure, there was a nearly 3-fold increase (p=.010) in FASN expression compared to non -obese control. Obese sera exposure increased sensitivity and decrease cell viability to TVB-3166 treatment compared to non-obese sera. ChIP-qPCR against anti-SREBP showed an increase in FASN expression upon treatment with insulin compared to normal rabbit IgG control. This increase in FASN expression was attenuated upon treatment with the SREBP processing inhibitor, Betulin. CONCLUSION: The overexpression of FASN contributes to obesity-induced breast cancer aggression and is regulated by an insulin-SREBP-FASN signaling axis. Citation Format: Bryan Mcclellan, Tommy Pham, Brittany Harlow, Gabby Lee, Duan Quach, Christopher Jolly, Andrew Brenner, Linda deGraffenried. Fatty acid synthase enzyme as a mediator of obesity-induced breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-22.

Background: Obesity is associated with prostate cancer progression and mortality. Previous studies in our laboratory suggest that obesity drives prostate cancer progression in part by increasing macrophage recruitment and by polarizing macrophages in the tumor microenvironment into a tumor promoting M2/TAM phenotype. Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, has been used for several decades in transplant patients, and in the last several years has been shown to be an effective disease suppressor in certain cancer types. Intriguingly, mTOR has been shown to be especially important for M2 polarization and stabilization. Hypothesis: Based upon published data and our preliminary studies, we hypothesize that rapamycin will selectively target obesity-polarized macrophages and will provide a survival benefit to the obese prostate cancer patient. Methods: To address this hypothesis, we used our in vitro model of obesity-induced macrophage polarization that includes two different prostate cancer cell lines, macrophages, and sera from obese and non-obese men. qPCR was used to measure expression levels of markers associated with an M2/TAM phenotype. MTT assays were conducted to measure cell viability, and flow cytometry and Western blot analyses were used to determine cell cycle status and apoptosis. Results: Obese conditions increased expression of M2/TAM markers in macrophages and rapamycin selectively decreased viability of obesity-activated M2/TAMs compared to M1 macrophages. Conclusions: Our in vitro study suggests that obesity promotes a tumor-associated phenotype in macrophages and that the mTOR pathway is involved in the survival of M2/TAM macrophages. This study offers a novel mechanistic approach to treat obese patients with prostate cancer. Citation Format: Gloria C. Galván, Tommy Pham, Brittany Harlow, Christian Johnson, Riddhi Patodia, Duan Quach, Michael A. Liss, Linda A. deGraffenried. Rapamycin selectively targets obesity-polarized macrophages in the prostate tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4004. doi:10.1158/1538-7445.AM2017-4004