Biology subjects

Hoy, A. J.

Publications and source records attributed to Hoy, A. J..

9 recordsLinked to original sources

bioRxiv2024

Cis-vaccenic acid is a key product of stearoyl-CoA desaturase 1 and a critical oncogenic factor in prostate cancer

Altered monounsaturated fatty acid (MUFA) metabolism is a hallmark of oncogenic transformation. Recently, the MUFA cis-vaccenic acid (cVA) was identified as a putative regulator of prostate cancer cell viability. cVA production requires the activity of stearoyl CoA desaturase 1 (SCD1), an enzyme frequently dysregulated in cancer, but the role of cVA in regulating cancer cell phenotypes has not been extensively explored, compared with the more commonly studied product and structural isomer of cVA, oleic acid. Here, we utilised SCD1 inhibition to study the effects of cVA in prostate cancer cells. We found that cVA consistently rescues reductions in cell viability due to SCD1 inhibition and promotes cell growth under normal conditions, thereby identifying cVA as an important and previously unrecognised product of SCD1 in prostate cancer. More broadly, we demonstrate that individual MUFA species exert a diverse range of influence on oncogenic phenotypes, highlighting a need to more precisely characterise the lipidome of cancer cells to understand the molecular pathology of the disease.

cell biology↗

bioRxiv2024

Fatty acids are not a significant contributor to the TCA cycle in cancer cell lines: evidence of incomplete fatty acid oxidation.

Upregulated fatty acid oxidation (FAO) is a hallmark of many aggressive cancers and is widely presumed to fuel the tricarboxylic acid (TCA) cycle for ATP production. However, the quantitative relationship between FAO capacity and its contribution to mitochondrial metabolism relative to other fuels remains unclear. Here, we combined parallel stable-isotope tracing with metabolic phenotyping across a diverse panel of 27 cancer cell lines to reveal a fundamental capacity-contribution paradox. Despite exhibiting FAO rates that varied over eight-fold, exogenous long-chain fatty acids consistently contributed minimally (<10%) to TCA cycle intermediates in all cancer cell lines. We demonstrated that FAO functions as a compensatory source of acetyl-CoA in cells with limited glucose-derived acetyl-CoA synthesis, rather than acting as a primary fuel source. In this context, high FAO rates do not primarily result from FAO-mediated suppression of glucose oxidation, but instead reflect the recruitment of fatty acid- and glutamine-derived carbons via a malic enzyme-dependent shunt to sustain the mitochondrial acetyl-CoA pool while preserving glucose-derived anaplerotic flux. These findings challenge the prevailing view that FAO serves as a primary bioenergetic fuel in cancer, instead identifying it as a compensatory rheostat that supplements acetyl-CoA supply in glucose-limited settings by working together with glutamine-driven, malic enzyme-dependent anaplerosis, providing a mechanistic framework to reinterpret the efficacy of FAO inhibitors beyond simple caloric starvation.

cancer biology↗

bioRxiv2024

Pathway metabolite ratios reveal distinctive glutamine metabolism in a subset of proliferating cells

Large-scale metabolomic analyses of pan-cancer cell line panels have provided significant insights into the relationships between metabolism and cancer cell biology. Here, we took a pathway-centric approach by transforming targeted metabolomic data into ratios to study associations between reactant and product metabolites in a panel of cancer and non-cancer cell lines. We identified five clusters of cells from various tissue origins. Of these, cells in Cluster 4 had high ratios of TCA cycle metabolites relative to pyruvate, produced more lactate yet consumed less glucose and glutamine, and greater OXPHOS activity compared to Cluster 3 cells with low TCA cycle metabolite ratios. This was due to more glutamine cataplerotic efflux and not glycolysis in cells of Cluster 4. In silico analyses of loss-of-function and drug sensitivity screens showed that Cluster 4 cells were more susceptible to gene deletion and drug targeting of lactate and glutamine metabolism, and OXPHOS than cells in Cluster 3. Our results highlight the potential of pathway-centric approaches to reveal new aspects of cellular metabolism from metabolomic data.

cancer biology↗

bioRxiv2024

CPT1a regulates the delivery of extracellular fatty acids for cardiolipin turnover in prostate cancer cells.

Mitochondrial fatty acid oxidation (FAO) has been proposed to be a major bioenergetic pathway in prostate cancer. However, this concept fails to consider FAO relative to other mitochondrial substrates. Here, we found extracellular long-chain fatty acids (LCFAs), including palmitate, stearate, oleate, linoleate, linolenate, are minor sources of carbon entering the TCA cycle compared to glucose and glutamine in prostate cancer cells, despite being assimilated in the mitochondria as acyl-carnitines. In contrast, cardiolipins were a prominent LCFAs sink, with some species achieving greater than 50% 13C-labelling within 6 hours, suggesting high cardiolipin turnover using extracellular LCFAs. Knockdown of CPT1a, the rate-limiting enzyme of LCFA entry into mitochondria, reduced the incorporation of extracellular linoleate into cardiolipins. These results demonstrate that FAO is not a major input for the TCA cycle and provide evidence for an underappreciated role for CPT1a in regulating LCFAs entry into mitochondria for cardiolipin remodelling.

cancer biology↗

bioRxiv2023

Acetyl-CoA carboxylase 1-dependent lipogenesis drives breast cancer progression

Dysregulation of cellular energetics, including lipid synthesis mediated through de novo lipogenesis, is a feature of many cancers. Here we report that acetyl-coenzyme A carboxylase (ACC) 1, the rate-limiting enzyme of de novo lipogenesis, is a key regulator of breast cancer progression and cancer cell phenotype. Mammary epithelial-specific deletion of ACC1 impaired tumour progression and decreased cancer cell proliferation in the PyMT model of breast cancer in vivo. ACC1 knockout in human breast cancer cell lines resulted in decreased cell number and altered cell and membrane morphology. Lipidomic profiling demonstrated reduced levels of acyl-carnitines (CARs) and several phospholipid (PL) classes, whilst also shifting the lipid profiles to exhibit more elongated and less saturated lipids in ACC1 knockout breast cancer cells. Palmitate rescue of ACC1 deletion phenotypes demonstrated a critical role for ACC1 driven de novo lipogenesis in breast cancer cell function. Analysis of human breast tumour-microarrays identified strong ACC1 expression at all breast cancer stages, grade and metastasis, compared to normal adjacent tissue. Together our data demonstrate a novel role for ACC1 in breast cancer progression and cancer cell function, mediated through its lipogenic role, that together with its expression profile, identify ACC1 as a potential therapeutic target in breast cancer. Statement of significanceThis study investigates the impact of ACC1 deletion in breast cancer progression, revealing the importance of ACC1-derived lipids in breast cancer cell phenotypes and identifies ACC1 as a potential novel therapeutic target.

cancer biology↗

bioRxiv2023

Hepatic Lipid Droplet-Associated Proteome Changes Distinguish Dietary-Induced Fatty Liver from Insulin Resistance in Male Mice.

Fatty liver is characterised by the expansion of lipid droplets and is associated with the development of many metabolic diseases, including insulin resistance, dyslipidaemia and cardiovascular disease. We assessed the morphology of hepatic lipid droplets and performed quantitative proteomics in lean, glucose-tolerant mice compared to high-fat diet (HFD) fed mice that displayed hepatic steatosis and glucose intolerance as well as high-starch diet (HStD) fed mice who exhibited similar levels of hepatic steatosis but remained glucose tolerant. Both HFD and HStD-fed mice had more and larger lipid droplets than Chow-fed animals. We observed striking differences in liver lipid droplet proteomes of HFD and HStD-fed mice compared to Chow-fed mice, with fewer differences between HFD and HStD. Taking advantage of our diet strategy, we identified a fatty liver lipid droplet proteome consisting of proteins common in HFD- and HStD-fed mice. Likewise, a proteome associated with glucose tolerance that included proteins common in Chow and HStD but not HFD-fed mice was identified. Notably, glucose intolerance was associated with changes in the ratio of adipose triglyceride lipase (ATGL) to perilipin 5 (PLIN5) in the lipid droplet proteome, suggesting dysregulation of neutral lipid homeostasis in glucose-intolerant fatty liver, which supports bioactive lipid synthesis and impairs hepatic insulin action. We conclude that our novel dietary approach uncouples ectopic lipid burden from insulin resistance-associated changes in the hepatic lipid droplet proteome.

cell biology↗

bioRxiv2022

ACSM1 and ACSM3 regulate prostate cancer fatty acid metabolism to promote tumour growth and constrain ferroptosis

Prostate tumours are highly reliant on lipids for energy, growth and survival. Activity of the androgen receptor (AR) is associated with reprogramming of lipid metabolic processes in prostate cancer, although the molecular underpinnings of this relationship remain to be fully elucidated. Here, we identified Acyl-CoA Synthetase Medium Chain Family Members 1 and 3 (ACSM1 and ACSM3) as AR-regulated mediators of prostate cancer metabolism and growth. ACSM1 and ACSM3 are upregulated in prostate tumours compared to non-malignant tissues and other cancer types. Both enzymes enhanced proliferation and protected PCa cells from death in vitro, while silencing ACSM3 led to reduced tumour growth in an orthotopic xenograft model. We show that ACSM1 and ACSM3 are major regulators of the PCa lipidome and enhance energy production via fatty acid oxidation. Metabolic dysregulation caused by loss of ACSM1/3 led to mitochondrial oxidative stress, lipid peroxidation and cell death by ferroptosis. Conversely, over-expression of ACSM1/3 enabled PCa cells to survive toxic doses of medium chain fatty acids and promoted resistance to ferroptosis-inducing drugs and AR antagonists. Collectively, these studies uncover a new link between AR and lipid metabolism and position ACSM1 and ACSM3 as key players in prostate cancer progression and therapy resistance.

cancer biology↗

bioRxiv2020

A feedback loop between the androgen receptor and 6-phosphogluoconate dehydrogenase (6PGD) drives prostate cancer growth

Alterations to androgen receptor (AR) signalling and cellular metabolism are hallmarks of prostate cancer. This study uncovers a novel link between AR and the pentose phosphate pathway (PPP) through 6-phosphogluoconate dehydrogenase (6PGD), an androgen-regulated gene that is upregulated in prostate cancer. Knockdown of 6PGD impairs growth and elicits death of prostate cancer cells, at least in part due to oxidative stress. Targeting 6PGD using 2 specific inhibitors, physcion and S3, was efficacious in multiple models of prostate cancer, including aggressive castration-resistant models. Importantly, S3 also suppressed proliferation of clinical patient-derived explants (PDEs). Mechanistically, 6PGD decreased expression and activity of AR in cell lines and PDEs, revealing a novel positive feedback loop between these factors. The enhanced efficacy of co-targeting AR and 6PGD further supported the biological relevance of this feedback. This work provides insight into the dysregulated metabolism of prostate cancer and supports investigation of co-targeting AR and the PPP.

cancer biology↗

bioRxiv2019

DECR1 is an androgen-repressed survival factor that regulates PUFA oxidation to protect prostate tumor cells from ferroptosis

Fatty acid {beta}-oxidation (FAO) is the main bioenergetic pathway in prostate cancer (PCa) and a promising novel therapeutic vulnerability. Here we demonstrate therapeutic efficacy of targeting FAO in clinical prostate tumors cultured ex vivo, and identify DECR1, which encodes the rate-limiting enzyme for oxidation of polyunsaturated fatty acids (PUFAs), as robustly overexpressed in PCa tissues and associated with shorter relapse-free survival. DECR1 is a negatively-regulated androgen receptor (AR) target gene and, therefore, may promote PCa cell survival and resistance to AR targeting therapeutics. DECR1 knockdown in PCa cells selectively inhibited {beta}-oxidation of PUFAs, inhibited proliferation and migration of PCa cells, including treatment resistant lines, and suppressed tumor cell proliferation in vivo. Mechanistically, targeting of DECR1 caused cellular accumulation of linoleic acid, enhanced mitochondrial oxidative stress and lipid peroxidation, and ferroptosis. These findings implicate PUFA oxidation via DECR1 as a previously unexplored facet of FAO that promotes survival of PCa cells.

cancer biology↗