The overall objective of this study is to define the role of obesity in activating the NF-?B pathway in ovarian cancer tumor-initiating cells (TICs) to facilitate tumor growth and chemoresistance. Ovarian cancer is the most lethal gynecological malignancy in the United States and although most patients initially respond to platinum- based chemotherapy, over 70% of advanced stage tumors relapse leading to high morbidity and mortality. One risk factor for the development of ovarian cancer is obesity, a condition associated with disease progression and poor outcomes after initial treatment. Studies show that a high fat diet and obesity activate the NF-?B signaling pathway to trigger inflammation. NF-?B is a ubiquitous signaling pathway whose target genes encode proteins that regulate immune response, cell survival, proliferation, adhesion, and interaction with the microenvironment. NF-?B is aberrantly activated in ovarian cancer and promotes a TIC phenotype necessary for chemotherapy resistance. It is unknown what factor(s) trigger NF-?B activation in ovarian cancer cells. This proposal investigates the hypothesis that adipocytes (fat cells that comprise adipose tissue) secrete factors that activate NF-?B pathways in ovarian cancer cells to drive tumor growth and chemotherapy resistance.
Aim 1 will test whether obesity enriches for ovarian cancer TICs through the secretion of adipokines. This will be investigated through co-culture experiments of ovarian cancer cells with patient-derived adipocytes to measure adipokine secretion, gene expression changes, enrichment of cancer cells with TIC features, and tumor growth in vivo.
Aim 2 will determine how inflammatory stimuli lead to differential NF-?B activation in ovarian cancer cells. NF-?B signaling cascades will be examined after exposure to inflammatory cytokines and adipokines prominent in the ovarian tumor microenvironment. NF-?B reporter activity, DNA binding, transcription factor activation, and pharmacological inhibition will be used to investigate NF-?B proteins critical for inflammation-induced signaling and tumor formation.
Aim 3 will discover why chemotherapy resistance of ovarian cancer cells is enhanced in the obese setting. Chemotherapy sensitivity and changes in pathways known to mediate drug resistance (NF- kB, AKT, STAT3) will be evaluated in ovarian cancer cells cultured with adipocytes. A novel therapeutic that targets obesity, inhibits NF-?B, and effectively eliminates TICs in vitro will be tested in vivo for its ability to prevent chemotherapy resistance and trigger tumor regression in an obese mouse model of ovarian cancer. Results of this proposal will advance the ovarian cancer field by providing mechanistic insight into the role of obesity in disease progression and chemotherapy resistance. Completion of the proposal aims will provide novel information about ovarian cancer biology and the role of adipocytes and NF-?B in promoting TICs. Knowledge gained from these studies will lead to more effective preventive and therapeutic strategies for cancers in which obesity is a risk factor.