Abstract 3018: Targeting lipid metabolism and diet in advanced prostate cancer
Authors: Rodrigues Silvia D. , Ribeiro Caroline Fidalgo , Tamarindo Guilherme H. , Pakula Hubert , Loda Massimo 
Published: June 2022

Abstract
Lipid metabolism reprogramming provides the energetic needs of prostate cancer cells (PCa) to support growth and cell progress through the cell cycle, sustaining a highly proliferative phenotype by increasing the expression levels of several enzymes involved in fatty acid (FAs) synthesis. Fatty acid synthase (FASN), a key enzyme in de novo fatty acid lipogenesis (DNL), is upregulated in metastatic, castration-resistant prostate cancer (CRPC), and its overexpression is related to carcinogenesis, growth, and metastasis. We previously demonstrated that FASN inhibitors show antitumor activity suppressing PCa cell proliferation and slowing tumor growth, both in vitro and in vivo, via rewiring of lipid cancer metabolism and inducing endoplasmic reticulum stress.We observed that impairment of DNL increases polyunsaturated fatty acids (PUFA) uptake as a compensatory mechanism of survival. Exogenously acquired PUFAs cause the remodeling of the prostate cancer cell lipidome, manifesting an enhanced acyl chain unsaturation across several lipid species. Lipid peroxidation and ROS accumulation are also observed, suggesting cell susceptible to oxidative damage following FASN blockade. Alterations in metabolic pathways cause a higher uptake of acetate and glutamine in PCa cells, as assessed by 14C-nutrient incorporation following FASN inhibition. Mitochondrial dysfunction is induced by reduction in several respiratory parameters, including ATP production and basal respiration. This may be, at least in part, the result of a reduction in phosphatidylglycerol, a cardiolipin precursor, altering mitochondrial membrane composition. Supplementation with the PUFA docosahexaenoic acid (DHA) increases phosphatidylcholine levels and total phospholipid acyl chain unsaturation, which can lead to membrane disorganization in prostate cancer cells. Superoxide anion production is enhanced by DHA treatment, as expected, and increased levels of glucose and palmitate oxidation by mitochondria are observed. Interestingly, AR and AR-V7 protein expression, as well as c-MYC and PSA, is reduced with DHA treatment. We then evaluated how de novo lipid synthesis inhibition combined with manipulation of the exogenous supply of fatty acids could impair tumor cell progression. Due to the obligate cell dependence on PUFA following DNL suppression, we combined FASN and Acetyl-CoA carboxylase (ACC) inhibitors with DHA supplementation and observed a significant cell growth inhibition in CRPC cell lines and prostate cancer organoids.Altogether, our results suggest a novel mechanism to inhibit the growth of castration-resistant prostate cancer, combining lipogenesis inhibition with PUFA-enriched diet to overcome advanced disease.
Citation Format: Silvia D. Rodrigues, Caroline Fidalgo Ribeiro, Guilherme H. Tamarindo, Hubert Pakula, Massimo Loda. Targeting lipid metabolism and diet in advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3018.