Abstract B067: Genetic and pharmacological inhibition of phospholipase D1 reduces pancreatic carcinogenesis in mice

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDA) is a leading cause of cancer-related death in the United States and is characterized by its sudden manifestation, poor prognosis, high incidence of metastasis, and aggressive tumor growth. Phospholipase D1 (PLD1) is a lipid-signaling enzyme that plays a role in signaling pathways that lead to cell proliferation, survival/apoptosis as well as downstream oncogenic transformation involved in cancer progression. PLD1 activity has been shown to promote tumor progression in other cancer types, however, the role and mechanisms of PLD1 in pancreatic cancer is not yet understood. The objective of this study is to determine the role of PLD1 regulation in pancreatic carcinogenesis through genetic-ablation and pharmacological inhibition of PLD1. In this study, we crossed the LSL-KrasG12D/+;Ptf1Cre/+ (KC) mice into PLD1 knockout (Pld1-/-) mice to generate KC; Pld1-/- mice in the C57BL/6 background to examine whether PLD1 is required for pancreatic tumorigenesis. Cohorts of male and female KC and KC; Pld1-/- mice, (8-12 mice per group), were euthanized at 4 and 8 months old and the pancreas was carefully resected. At 8 months of age, there was a significant difference (p<0.05) in the pancreas weight at sacrifice between the KC mice and the KC; Pld1-/- mice in a sex-dependent manner. This was due, in part, by a reduction in tumor proliferation as determined by Ki67 expression. To assess whether pharmacological inhibition of PLD could prevent pancreatic carcinogenesis in KC mice, cohorts of 9-12 male 7-month-old KC mice received daily intraperitoneal injections of a small molecule inhibitor of PLD (FIPI) at a dosage of 3 mg/kg of body weight for a duration of 5 weeks. The mice were euthanized at 8.5 months of age and the pancreas was carefully resected. Histological analysis indicated that FIPI-treated KC mice displayed less acinar cell loss compared to vehicle-treated KC controls. Moreover, treatment with FIPI significantly reduced cell proliferation (p<0.01) in KC mice in comparison to vehicle-treated KC mice. In summary, these results indicate that PLD1 plays a critical role in pancreatic carcinogenesis and may represent a novel therapeutic target. Additional studies are underway to explore the cellular mechanisms of how PLD1 inhibition modulates pancreatic carcinogenesis. Citation Format: Hala A. Addassi, Gerardo G. Mackenzie. Genetic and pharmacological inhibition of phospholipase D1 reduces pancreatic carcinogenesis in mice [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B067.