Abstract 5259: Urolithin A prevents pancreatic tumor growth and increases survival by inhibiting PI3K/PDK1 and STAT3 signaling

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer-related mortality in the United States. Most patients present with an advanced disease and the majority die within five years, many surviving less than six months. Cytotoxic chemotherapy including Gemcitabine (Gem), FOLFIRINOX, nab-paclitaxel offer modest improvement in survival, albeit at the cost of increased side effects and unwanted toxicities. Therefore, developing novel chemotherapeutic agents for PDAC treatment is critical to improve survival. Ellagic acid/ellatitannins are abundantly present in the pomegranate and berries, are actively metabolized by the intestinal microflora to Urolithin A (UA). Oral administration of UA has shown to be highly bioavailable and non-toxic. UA inhibits multiple kinases that are known to be involved in PDAC progression and metastasis. Therefore, we hypothesized that UA would elicit potent anti-cancer therapeutic potential in PDAC. The effect of UA on kinase activity was assessed . Inhibition of AKT (downstream of PI3K/PDK1), p70 S6 Kinase (PS6K) and STAT3 activation was quantified in PDAC cells treated with UA in dose-dependent manner. The mechanism of action was validated for UA’s activity on PI3K/PDK1, PS6K and STAT3 activation using immunoblot analysis. MiaPaCa2 cells were treated with specific inhibitors for either AKT (MK2206) or STAT3 (AZD1480) and analyzed for tumorigenicity. UA treated PDAC cells were analyzed for cell proliferation, cell invasion and colony formation. Cell cycle analysis and cell apoptosis were measured by flow cytometry. To test the efficacy of UA in vivo, cells were implanted subcutaneously in athymic nude mice. The animals received UA daily and tumor volume was measured for 5 weeks. Next, we assessed tumor growth and overall survival (OS) in PKT (Ptf1acre/+;LSL-KrasG12D;Tgfbr2fl/fl) mice, an aggressive genetically engineered PDAC mouse model, in response to UA and/or Gem treatment. Tissues from the xenografts and PKT mice treated with vehicle or UA were analyzed for cell proliferation (Ki67) and apoptosis (cleaved Caspase 3) by immunohistochemistry. High expression levels of activated STAT3 or AKT correlate with decreased survival in PDAC. UA treated MiaPaCa2 cells showed significant dose-dependent increase in apoptosis and decrease in anchorage-independent growth. UA inhibited AKT, PS6K and STAT3 signaling. As a single agent, UA effectively reduced in vivo PDAC tumor growth. Immunohistochemistry of UA treated tissues from tumor xenografts and PKT mice showed inhibition of Ki67 positive tumor cells and increased cleaved caspase 3 staining. PKT mice treated with UA showed a decrease in tumor size and an increased OS when compared to vehicle or Gem treated mice alone. These findings show that UA is a novel inhibitor/modulator/regulator for multiple signaling pathways in PDAC. These results suggest UA has potential for pre-clinical development in pancreatic cancer. Citation Format: Supriya Srinivasan, Venkatakrishna Jala, Kumar Honnenahally, Jason Castellanos, Praveen Kumar Vermula, Michael VanSaun, Nipun Merchant, Nagaraj Nagathihalli. Urolithin A prevents pancreatic tumor growth and increases survival by inhibiting PI3K/PDK1 and STAT3 signaling [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 5259. doi:10.1158/1538-7445.AM2017-5259