Abstract 1467: Metabolic reprogramming fuels prostate cancer cells towards enzalutamide resistance
Authors: Verma Shiv S. , Shankar Eswar , Kanwal Rajnee , Chan Ricky , Gupta Sanjay 
Published: September 2020

Abstract
Androgen deprivation therapy is standard care for advanced-stage prostate cancer. Enzalutamide (Xtandi®), a second-generation antiandrogen is the most clinically prescribed drug that has prolonged survival in men. However, this response is temporary and results in the rapid emergence of resistance. The underlying mechanisms of enzalutamide resistance remain unclear. Emerging evidence suggests that metabolic reprogramming mediates resistance to standard-of-care therapies. To identify the molecular underpinnings of enzalutamide resistance, we performed Next-Gen Sequencing (NGS), analyzing global metabolic changes in enzalutamide-resistant clones utilizing two androgen-responsive human prostate cancer cells and comparing them with parental counterparts. Enzalutamide-resistant LNCaP and C4-2B cells were generated from 20µM enzalutamide exposed for 6 months and maintained in media containing 5µM drug, referred to as LNCaP/C42B ENZU cells. Gene set enrichment analysis of differentially expressed genes (DEGs) demonstrated an overlap between genes of metabolic signaling pathways together with fatty acid signaling, fatty acid β oxidation, drug resistance, bile acid biosynthesis, lipid metabolism, and peroxisome signaling. Interestingly, NGS data of LNCaP-ENZU cells showed a higher number of DEGs genes associated with metabolic reprogramming, compared to C42B-ENZU cells. Analysis of LNCaP-ENZU cells exhibited more than 10 fold higher (log2 fold) expression of XIST, AKT3, ZNF655, IRS4, HOXB3, FBN2, FHL1, GSTP1, VCAN, KIAA0408 genes; whereas ZNF544, KLK2, CSMD1, ZG16B, SPDEF, AR, C1R1, FOLH1, HISTIHIB, and TNPR222 were downregulated (-10 to -12 log2 fold), compared to parental counterpart. The majority of these genes belong to the metabolic regulatory network. Furthermore, genes viz. AKT3, HOXB3, and KIA0048 RALYL and KLK2 exhibited interaction with androgen receptor (AR), and may influence the ligand-binding domain of AR resulting in stimulation of AR/AR targeted genes. Q-PCR data were in agreement with NGS data where the signature genes associated with the metabolic synthesis of fatty acid, lipid and glucose were overexpressed in LNCaP-ENZU cells. In particular, fatty acid synthesis genes viz. ACADL, ACSL4, FHL2, and SLC27A6 were high up to 14.7, 15.8, 6.02 and 17.8 log2 fold value. Expression of solute carrier SLC12A5, SLC13A4, SLC24A4, SLC30A3, SLC35D1, and SLC47A1 genes showed 1195, 5, 20.01, 4.6, 9.5, and 4.3 log2 fold higher expression, which function in increasing the nucleotide-sugar transmembrane transporter activity. Expression of lipid-associated genes viz. ABCB4, CYP2D6, CYP4X1, CYP39A1, and SLC25A17 exhibited 30, 25.6, 25.5, 8.4, and 17.5 log2 fold higher expression. These gene expression correlated with higher-end products of TCA cycle, glucose metabolism, citric acid and lactate production in LNCaP ENZU-resistant cells. Taken together, our findings demonstrate molecular alterations after enzalutamide exposure may provide fuel to the cells through metabolic reprogramming. Clinically, targeting the aforementioned genes associated with metabolic reprogramming may lead to control of the enzalutamide-mediated recurrence of prostate cancer.
Citation Format: Shiv S. Verma, Eswar Shankar, Rajnee Kanwal, Ricky Chan, Sanjay Gupta. Metabolic reprogramming fuels prostate cancer cells towards enzalutamide resistance [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1467.