GPR1 and CMKLR1 control lipid metabolism to support development of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC), the most common type of kidney cancer, is largely incurable in the metastatic setting. ccRCC is characterized by excessive lipid accumulation that protects cells from stress and promotes tumor growth, suggesting that the underlying regulators of lipid storage could represent potential therapeutic targets. Here, we evaluated the regulatory roles of GPR1 and CMKLR1, two G-protein coupled receptors of the pro-tumorigenic adipokine chemerin that is involved in ccRCC lipid metabolism. Both genetic and pharmacological suppression of either receptor suppressed lipid formation and induced multiple forms of cell death, including apoptosis, ferroptosis and autophagy, significantly impeding ccRCC growth in cell lines and patient derived xenograft (PDX) models. Comprehensive lipidomic and transcriptomic profiling of receptor competent and depleted cells revealed overlapping and unique signaling of the receptors granting control over triglyceride synthesis, ceramide production, and fatty acid saturation and class production. Mechanistically, the receptors both enforced suppression of the triglyceride lipase ATGL but also demonstrated distinct functions, such as the unique ability of CMKLR1 to control lipid uptake through regulation of SREBP1c and the CD36 scavenger receptor. Treating PDX models with the CMKLR1-targeting small molecule α-NETA led to a dramatic reduction of tumor growth, lipid storage, and clear cell morphology. Together, these findings provide mechanistic insight into lipid regulation in ccRCC and identify a targetable axis at the core of the histological definition of this tumor that could be exploited therapeutically.

An IROA Workflow for correction and normalization of ion suppression in mass spectrometry-based metabolomic profiling data

Ion suppression is a major problem in mass spectrometry (MS)-based metabolomics; it can dramatically decrease measurement accuracy, precision, and signal-to-noise sensitivity. Here we report a new method, the IROA TruQuant Workflow, that uses a stable isotope-labeled internal standard (IROA-IS) plus novel companion algorithms to 1) measure and correct for ion suppression, and 2) perform Dual MSTUS normalization of MS metabolomic data. We have evaluated the method across ion chromatography (IC), hydrophilic interaction liquid chromatography (HILIC), and reverse phase liquid chromatography (RPLC)-MS systems in both positive and negative ionization modes, with clean and unclean ion sources, and across different biological matrices. Across the broad range of conditions tested, all detected metabolites exhibited ion suppression ranging from 1% to 90+% and coefficient of variations ranging from 1% to 20%, but the Workflow and companion algorithms were highly effective at nulling out that suppression and error. Overall, the Workflow corrects ion suppression across diverse analytical conditions and produces robust normalization of non-targeted metabolomic data.

Intratumoral Biosynthesis of Gold Nanoclusters by Pancreatic Cancer to Overcome Delivery Barriers to Radiosensitization

Nanoparticle delivery to solid tumors is a prime challenge in nanomedicine. Here, we approach this challenge through the lens of biogeochemistry, the field that studies the flow of chemical elements within ecosystems as manipulated by living cellular organisms and their environments. We leverage biogeochemistry concepts related to gold cycling against pancreatic cancer, considering mammalian organisms as drivers for gold nanoparticle biosynthesis. Sequestration of gold nanoparticles within tumors has been demonstrated as an effective strategy to enhance radiotherapy; however, the desmoplasia of pancreatic cancer impedes nanoparticle delivery. Our strategy overcomes this barrier by applying an atomic-scale agent, ionic gold, for intratumoral gold nanoparticle biosynthesis. Our comprehensive studies showed the cancer-specific synthesis of gold nanoparticles from externally delivered gold ions in vitro and in a murine pancreatic cancer model in vivo; a substantial colocalization of gold nanoparticles (GNPs) with cancer cell nuclei in vitro and in vivo; a strong radiosensitization effect by the intracellularly synthesized GNPs; a uniform distribution of in situ synthesized GNPs throughout the tumor volume; a nearly 40-day total suppression of tumor growth in animal models of pancreatic cancer treated with a combination of gold ions and radiation that was also associated with a significantly higher median survival versus radiation alone (235 vs 102 days, respectively).

Imipridones inhibit tumor growth and improve survival in an orthotopic liver metastasis mouse model of human uveal melanoma

Purpose

Uveal melanoma (UM) is a highly aggressive disease with very few treatment options. We previously demonstrated that mUM is characterized by high oxidative phosphorylation (OXPHOS). Here we tested the anti-tumor, signaling and metabolic effects of imipridones, CLPP activators which reduce OXPHOS indirectly and have demonstrated safety in patients.

Experimental Design

We assessed CLPP expression in UM patient samples. We tested the effects of imipridones (ONC201, ONC212) on the growth, survival, signaling and metabolism of UM cell lines in vitro, and for therapeutic effects in vivo in UM liver metastasis models.

Results

CLPP expression was confirmed in primary and mUM patient samples. ONC201/212 treatment of UM cell lines in vitro decreased OXPHOS effectors, inhibited cell growth and migration, and induced apoptosis. ONC212 increased metabolic stress and apoptotic pathways, inhibited amino acid metabolism, and induced cell death-related lipids. ONC212 also decreased tumor burden and increased survival in vivo in two UM liver metastasis models.

Conclusion

Imipridones are a promising strategy for further testing and development in mUM.

Cell cycle arrest induces lipid droplet formation and confers ferroptosis resistance

How cells coordinate cell cycling with cell survival and death remains incompletely understood. Here, we show that cell cycle arrest has a potent suppressive effect on ferroptosis, a form of regulated cell death induced by overwhelming lipid peroxidation at cellular membranes. Mechanistically, cell cycle arrest induces diacylglycerol acyltransferase (DGAT)-dependent lipid droplet formation to sequester excessive polyunsaturated fatty acids (PUFAs) that accumulate in arrested cells in triacylglycerols (TAGs), resulting in ferroptosis suppression. Consequently, DGAT inhibition orchestrates a reshuffling of PUFAs from TAGs to phospholipids and re-sensitizes arrested cells to ferroptosis. We show that some slow-cycling antimitotic drug-resistant cancer cells, such as 5-fluorouracil-resistant cells, have accumulation of lipid droplets and that combined treatment with ferroptosis inducers and DGAT inhibitors effectively suppresses the growth of 5-fluorouracil-resistant tumors by inducing ferroptosis. Together, these results reveal a role for cell cycle arrest in driving ferroptosis resistance and suggest a ferroptosis-inducing therapeutic strategy to target slow-cycling therapy-resistant cancers.

miRNA-211 maintains metabolic homeostasis in medulloblastoma through its target gene long-chain acyl-CoA synthetase 4

The prognosis of childhood medulloblastoma (MB) is often poor, and it usually requires aggressive therapy that adversely affects quality of life. microRNA-211 (miR-211) was previously identified as an important regulator of cells that descend from neural cells. Since medulloblastomas primarily affect cells with similar ontogeny, we investigated the role and mechanism of miR-211 in MB. Here we showed that miR-211 expression was highly downregulated in cell lines, PDXs, and clinical samples of different MB subgroups (SHH, Group 3, and Group 4) compared to normal cerebellum. miR-211 gene was ectopically expressed in transgenic cells from MB subgroups, and they were subjected to molecular and phenotypic investigations. Monoclonal cells stably expressing miR-211 were injected into the mouse cerebellum. miR-211 forced expression acts as a tumor suppressor in MB both in vitro and in vivo, attenuating growth, promoting apoptosis, and inhibiting invasion. In support of emerging regulatory roles of metabolism in various forms of cancer, we identified the acyl-CoA synthetase long-chain family member (ACSL4) as a direct miR-211 target. Furthermore, lipid nanoparticle-coated, dendrimer-coated, and cerium oxide-coated miR-211 nanoparticles were applied to deliver synthetic miR-211 into MB cell lines and cellular responses were assayed. Synthesizing nanoparticle-miR-211 conjugates can suppress MB cell viability and invasion in vitro. Our findings reveal miR-211 as a tumor suppressor and a potential therapeutic agent in MB. This proof-of-concept paves the way for further pre-clinical and clinical development.

Tumor-resident Lactobacillus iners confer chemoradiation resistance through lactate-induced metabolic rewiring

Tumor microbiota can produce active metabolites that affect cancer and immune cell signaling, metabolism, and proliferation. Here, we explore tumor and gut microbiome features that affect chemoradiation response in patients with cervical cancer using a combined approach of deep microbiome sequencing, targeted bacterial culture, and in vitro assays. We identify that an obligate L-lactate-producing lactic acid bacterium found in tumors, Lactobacillus iners, is associated with decreased survival in patients, induces chemotherapy and radiation resistance in cervical cancer cells, and leads to metabolic rewiring, or alterations in multiple metabolic pathways, in tumors. Genomically similar L-lactate-producing lactic acid bacteria commensal to other body sites are also significantly associated with survival in colorectal, lung, head and neck, and skin cancers. Our findings demonstrate that lactic acid bacteria in the tumor microenvironment can alter tumor metabolism and lactate signaling pathways, causing therapeutic resistance. Lactic acid bacteria could be promising therapeutic targets across cancer types.

TARO: tree-aggregated factor regression for microbiome data integration

Motivation

Although the human microbiome plays a key role in health and disease, the biological mechanisms underlying the interaction between the microbiome and its host are incompletely understood. Integration with other molecular profiling data offers an opportunity to characterize the role of the microbiome and elucidate therapeutic targets. However, this remains challenging to the high dimensionality, compositionality, and rare features found in microbiome profiling data. These challenges necessitate the use of methods that can achieve structured sparsity in learning cross-platform association patterns.

Results

We propose Tree-Aggregated factor RegressiOn (TARO) for the integration of microbiome and metabolomic data. We leverage information on the phylogenetic tree structure to flexibly aggregate rare features. We demonstrate through simulation studies that TARO accurately recovers a low-rank coefficient matrix and identifies relevant features. We applied TARO to microbiome and metabolomic profiles gathered from subjects being screened for colorectal cancer to understand how gut microrganisms shape intestinal metabolite abundances.

Availability and implementation

The R package TARO implementing the proposed methods is available online at https://github.com/amishra-stats/taro-package .

Augmenting Mitochondrial Respiration in Immature Smooth Muscle Cells with an ACTA2 Pathogenic Variant Mitigates Moyamoya-like Cerebrovascular Disease

ACTA2 pathogenic variants altering arginine 179 cause childhood-onset strokes due to moyamoya disease (MMD)-like occlusion of the distal internal carotid arteries. A smooth muscle cell (SMC)-specific knock-in mouse model (Acta2SMC-R179C/+) inserted the mutation into 67% of aortic SMCs, whereas explanted SMCs were uniformly heterozygous. Acta2R179C/+ SMCs fail to fully differentiate and maintain stem cell-like features, including high glycolytic flux, and increasing oxidative respiration (OXPHOS) with nicotinamide riboside (NR) drives the mutant SMCs to differentiate and decreases migration. Acta2SMC-R179C/+ mice have intraluminal MMD-like occlusive lesions and strokes after carotid artery injury, whereas the similarly treated WT mice have no strokes and patent lumens. Treatment with NR prior to the carotid artery injury attenuates the strokes, MMD-like lumen occlusions, and aberrant vascular remodeling in the Acta2SMC-R179C/+ mice. These data highlight the role of immature SMCs in MMD-associated occlusive disease and demonstrate that altering SMC metabolism to drive quiescence of Acta2R179C/+ SMCs attenuates strokes and aberrant vascular remodeling in the Acta2SMC-R179C/+ mice.

Niclosamide as a chemical probe for analyzing SARS-CoV-2 modulation of host cell lipid metabolism

Introduction

SARS-CoV-2 subverts host cell processes to facilitate rapid replication and dissemination, and this leads to pathological inflammation.

Methods

We used niclosamide (NIC), a poorly soluble anti-helminth drug identified initially for repurposed treatment of COVID-19, which activates the cells' autophagic and lipophagic processes as a chemical probe to determine if it can modulate the host cell's total lipid profile that would otherwise be either amplified or reduced during SARS-CoV-2 infection.

Results

Through parallel lipidomic and transcriptomic analyses we observed massive reorganization of lipid profiles of SARS-CoV-2 infected Vero E6 cells, especially with triglycerides, which were elevated early during virus replication, but decreased thereafter, as well as plasmalogens, which were elevated at later timepoints during virus replication, but were also elevated under normal cell growth. These findings suggested a complex interplay of lipid profile reorganization involving plasmalogen metabolism. We also observed that NIC treatment of both low and high viral loads does not affect virus entry. Instead, NIC treatment reduced the abundance of plasmalogens, diacylglycerides, and ceramides, which we found elevated during virus infection in the absence of NIC, resulting in a significant reduction in the production of infectious virions. Unexpectedly, at higher viral loads, NIC treatment also resulted in elevated triglyceride levels, and induced significant changes in phospholipid metabolism.

Discussion

We posit that future screens of approved or new partner drugs should prioritize compounds that effectively counter SARS-CoV-2 subversion of lipid metabolism, thereby reducing virus replication, egress, and the subsequent regulation of key lipid mediators of pathological inflammation.

The transcription factor ChREBP links mitochondrial lipidomes to mitochondrial morphology and progression of diabetic kidney disease

A substantial body of evidence has established the contributions of both mitochondrial dynamics and lipid metabolism to the pathogenesis of diabetic kidney disease (DKD). However, the precise interplay between these two key metabolic regulators of DKD is not fully understood. Here, we uncover a link between mitochondrial dynamics and lipid metabolism by investigating the role of carbohydrate-response element-binding protein (ChREBP), a glucose-responsive transcription factor and a master regulator of lipogenesis, in kidney podocytes. We find that inducible podocyte-specific knockdown of ChREBP in diabetic db/db mice improves key biochemical and histological features of DKD in addition to significantly reducing mitochondrial fragmentation. Because of the critical role of ChREBP in lipid metabolism, we interrogated whether and how mitochondrial lipidomes play a role in ChREBP-mediated mitochondrial fission. Our findings suggest a key role for a family of ether phospholipids in ChREBP-induced mitochondrial remodeling. We find that overexpression of glyceronephosphate O-acyltransferase, a critical enzyme in the biosynthesis of plasmalogens, reverses the protective phenotype of ChREBP deficiency on mitochondrial fragmentation. Finally, our data also points to Gnpat as a direct transcriptional target of ChREBP. Taken together, our results uncover a distinct mitochondrial lipid signature as the link between ChREBP-induced mitochondrial dynamics and progression of DKD.

Troponin I Elevation after Elective Percutaneous Coronary Interventions: Prevalence and Risk Factors

Percutaneous coronary intervention (PCI) is one of the most important modalities of treatment for coronary artery disease (CAD). Minor extents of injury to the myocardium have been observed even after successful PCI. This peri-procedural injury might therefore reduce some of the beneficial effects of coronary revascularization. The objective of this hospital based comparative observational study was to determine the prevalence of post procedural Cardiac troponin I (cTnI) elevation after elective PCI and also to find out the relation with risk factors such as age, sex, body mass index (BMI), smoking, anemia, diabetes mellitus, hypertension, dyslipidemia, family history, left ventricular dysfunction, renal insufficiency, type of stent, number of stent and length of stent. This was a hospital based comparative observational study carried out in the Department of Cardiology, Chattogram Medical College Hospital (CMCH), Chattogram, Bangladesh from July 2018 to June 2019. A total of 50 patients who underwent elective PCI were included as sampled by purposive sampling method. Serum cTnI was measured by FIA8000 quantitative immunoassay analyzer with an analytical measurement before and at 24 hours of PCI. Value >1.0ng/ml was considered elevated. Univariate and multivariate analysis were applied to assess predictors for the occurrence of post-procedural elevation of cTnI. The mean±SD age of the study population was 54.96±9.1 years (range 35-74 years) and 34(68.0%) patients were male. Regarding cardiovascular risk factors, 17(34.0%) patients had diabetes mellitus, 27(54.0%) had dyslipidemia, 30(60.0%) had hypertension, 32(64.0%) were current or ex-smokers and 20(40.0%) had a family history of CAD. Eighteen patients (36.0%) had post-procedural cTnI elevation but only 8(16.0%) had significant (>1.0ng/ml) elevation. Change of cTnI before and at 24 hours of PCI was not significant (p=0.057). Cardiac Troponin I increase was related to age, pre-procedural serum creatinine and multi-vessel stenting. Minor elevation of cTnI was common following elective PCI and associated with few risk factors such as elderly patient (more than 50 years), raised serum creatinine and multi-vessel stenting. So, early detection of these risk factors, as well as effective intervention may help to prevent injury to cardiac tissue hence stop elevation of cardiac TnI following elective PCI.

Dimeric p53 Mutant Elicits Unique Tumor-Suppressive Activities through an Altered Metabolic Program

Cancer-related alterations of the p53 tetramerization domain (TD) abrogate wild-type (WT) p53 function. They result in a protein that preferentially forms monomers or dimers, which are also normal p53 states under basal cellular conditions. However, their physiologic relevance is not well understood. We have established in vivo models for monomeric and dimeric p53, which model Li-Fraumeni syndrome patients with germline p53 TD alterations. p53 monomers are inactive forms of the protein. Unexpectedly, p53 dimers conferred some tumor suppression that is not mediated by canonical WT p53 activities. p53 dimers upregulate the PPAR pathway. These activities are associated with lower prevalence of thymic lymphomas and increased CD8+ T-cell differentiation. Lymphomas derived from dimeric p53 mice show cooperating alterations in the PPAR pathway, further implicating a role for these activities in tumor suppression. Our data reveal novel functions for p53 dimers and support the exploration of PPAR agonists as therapies.

SIGNIFICANCE

New mouse models with TP53R342P (monomer) or TP53A347D (dimer) mutations mimic Li-Fraumeni syndrome. Although p53 monomers lack function, p53 dimers conferred noncanonical tumor-suppressive activities. We describe novel activities for p53 dimers facilitated by PPARs and propose these are "basal" p53 activities. See related commentary by Stieg et al., p. 1046. See related article by Choe et al., p. 1250. This article is highlighted in the In This Issue feature, p. 1027.

Immune Profile of Exosomes in African American Breast Cancer Patients Is Mediated by Kaiso/THBS1/CD47 Signaling

African American (AA) women with breast cancer are more likely to have higher inflammation and a stronger overall immune response, which correlate with poorer outcomes. In this report, we applied the nanostring immune panel to identify differences in inflammatory and immune gene expression by race. We observed a higher expression of multiple cytokines in AA patients compared to EA patients, with high expression of CD47, TGFB1, and NFKB1 associated with the transcriptional repressor Kaiso. To investigate the mechanism associated with this expression pattern, we observed that Kaiso depletion results in decreased expression of CD47, and its ligand SIRPA. Furthermore, Kaiso appears to directly bind to the methylated sequences of the THBS1 promotor and repress gene expression. Similarly, Kaiso depletion attenuated tumor formation in athymic nude mice, and these Kaiso-depleted xenograft tissues showed significantly higher phagocytosis and increased infiltration of M1 macrophages. In vitro validation using MCF7 and THP1 macrophages treated with Kaiso-depleted exosomes showed a reduced expression of immune-related markers (CD47 and SIRPA) and macrophage polarization towards the M1 phenotype compared to MCF7 cells treated with exosomes isolated from high-Kaiso cells. Lastly, analysis of TCGA breast cancer patient data demonstrates that this gene signature is most prominent in the basal-like subtype, which is more frequently observed in AA breast cancer patients.

DAXX drives de novo lipogenesis and contributes to tumorigenesis

Cancer cells exhibit elevated lipid synthesis. In breast and other cancer types, genes involved in lipid production are highly upregulated, but the mechanisms that control their expression remain poorly understood. Using integrated transcriptomic, lipidomic, and molecular studies, here we report that DAXX is a regulator of oncogenic lipogenesis. DAXX depletion attenuates, while its overexpression enhances, lipogenic gene expression, lipogenesis, and tumor growth. Mechanistically, DAXX interacts with SREBP1 and SREBP2 and activates SREBP-mediated transcription. DAXX associates with lipogenic gene promoters through SREBPs. Underscoring the critical roles for the DAXX-SREBP interaction for lipogenesis, SREBP2 knockdown attenuates tumor growth in cells with DAXX overexpression, and DAXX mutants unable to bind SREBP1/2 have weakened activity in promoting lipogenesis and tumor growth. Remarkably, a DAXX mutant deficient of SUMO-binding fails to activate SREBP1/2 and lipogenesis due to impaired SREBP binding and chromatin recruitment and is defective of stimulating tumorigenesis. Hence, DAXX's SUMO-binding activity is critical to oncogenic lipogenesis. Notably, a peptide corresponding to DAXX's C-terminal SUMO-interacting motif (SIM2) is cell-membrane permeable, disrupts the DAXX-SREBP1/2 interactions, and inhibits lipogenesis and tumor growth. These results establish DAXX as a regulator of lipogenesis and a potential therapeutic target for cancer therapy.

The oncogenic circular RNA circ_63706 is a potential therapeutic target in sonic hedgehog-subtype childhood medulloblastomas

Medulloblastoma (MB) develops through various genetic, epigenetic, and non-coding (nc) RNA-related mechanisms, but the roles played by ncRNAs, particularly circular RNAs (circRNAs), remain poorly defined. CircRNAs are increasingly recognized as stable non-coding RNA therapeutic targets in many cancers, but little is known about their function in MBs. To determine medulloblastoma subgroup-specific circRNAs, publicly available RNA sequencing (RNA-seq) data from 175 MB patients were interrogated to identify circRNAs that differentiate between MB subgroups. circ_63706 was identified as sonic hedgehog (SHH) group-specific, with its expression confirmed by RNA-FISH analysis in clinical tissue samples. The oncogenic function of circ_63706 was characterized in vitro and in vivo. Further, circ_63706-depleted cells were subjected to RNA-seq and lipid profiling to identify its molecular function. Finally, we mapped the circ_63706 secondary structure using an advanced random forest classification model and modeled a 3D structure to identify its interacting miRNA partner molecules. Circ_63706 regulates independently of the host coding gene pericentrin (PCNT), and its expression is specific to the SHH subgroup. circ_63706-deleted cells implanted into mice produced smaller tumors, and mice lived longer than parental cell implants. At the molecular level, circ_63706-deleted cells elevated total ceramide and oxidized lipids and reduced total triglyceride. Our study implicates a novel oncogenic circular RNA in the SHH medulloblastoma subgroup and establishes its molecular function and potential as a future therapeutic target.

Abstract P6-11-14: Mitochondrial structure and function adaptation in residual triple negative breast cancer cells surviving chemotherapy treatment

Background: Neoadjuvant chemotherapy (NACT) used for triple-negative breast cancer (TNBC) eradicates tumors in only 45% of patients. TNBC patients with substantial residual cancer burden have poor metastasis-free and overall survival rates. Our previous studies demonstrated mitochondrial oxidative phosphorylation (OXPHOS) was elevated, suggesting a unique therapeutic dependency of residual tumor cells that survived after NACT. However, mechanisms underlying this enhanced reliance on OXPHOS are yet unknown. Mitochondria are morphologically plastic organelles that cycle between fission and fusion to maintain mitochondrial integrity and metabolic homeostasis. Methods: We modeled residual disease in human TNBC cells by treating with chemotherapeutic agents at the IC50 of cell killing, then evaluating surviving cells after 48 hours of treatment. We modeled residual TNBC in orthotopic patient-derived xenograft (PDX) model (PIM001p) by treating with standard front-line NACT (Adriamycin + cyclophosphamide; AC), then longitudinally harvesting tumors prior to treatment, residual, and upon regrowth. We analyzed mitochondrial morphology, mtDNA content and integrity, mitochondrial oxygen consumption rate, and metabolomic flux. We developed a U-Net based deep learning model that automatically detects and quantifies mitochondrial features in transmission electron micrographs. To test the functional dependency of mitochondrial structure in TNBC, we perturbed mitochondrial fusion genetically (by knocking down the fusion-driving protein Optic Atrophy 1, OPA1) and pharmacologically (using the first-in-class small molecule OPA1 inhibitor, MYLS22). Results: Pharmacologic or genetic disruption of mitochondrial fusion and fission resulted in decreased or increased OXPHOS rate, respectively, in TNBC cells, revealing for the first time that mitochondria morphology regulates OXPHOS in TNBC. Upon comparing mitochondrial effects of conventional chemotherapies, we found that DNA-damaging agents (adriamycin, carboplatin) increased mitochondrial elongation, mitochondrial content, flux of glucose through the TCA cycle, and OXPHOS, whereas taxanes (paclitaxel, docetaxel) instead decreased mitochondrial elongation and OXPHOS rate. Increased levels of the short protein isoform of OPA1 were observed in residual cells that not killed by DNA-damaging chemotherapy treatment. Treatment of cells with adriamycin followed by MYLS22 or given concurrently with MYLS22 drastically decreased cell growth. Conversely, cells treated with adriamycin, inducing fusion, followed by the DRP1 inhibitor Mdivi-1, further inducing fusion, were less sensitive to adriamycin than were vehicle-treated cells. Further, we observed heightened OXPHOS, OPA1 protein levels, and mitochondrial elongation in residual tumors of the PDX model following AC treatment. We found that sequential treatment first with AC, thus inducing mitochondrial fusion and OXPHOS, followed by MYLS22 to inhibit OPA1 in residual tumors, was able to suppress mitochondrial fusion and OXPHOS and significantly inhibited residual tumor regrowth. Our deep-learning algorithm identified distinct changes in mitochondrial phenotypes in residual tumors of multiple PDX models. Treatment of non-chemotherapy-treated mice with the OPA1 inhibitor MYLS22 as a single agent had no effect on tumor growth, revealing that post-AC residual tumors have an enhanced dependency on mitochondrial fusion compared to treatment-naïve tumors. Taken together, our findings establish a functional role for mitochondrial structure in chemotherapeutic response and metabolic reprogramming, which may confer survival advantage to TNBC cells. These results suggest that pharmacologic perturbation of mitochondrial structure can overcome chemoresistance in TNBC cells when administered rationally based on our understanding of chemotherapy-induced mitochondrial adaptations.

Citation Format: Lily Baek, Junegoo Lee, Katherine E. Pendleton, Mariah J. Berner, Emily Goff, Lin Tan, Sara Martinez, Iqbal Mahmud, Argenis Arriojas, Alexander Zhurkevich, Tao Wang, Matthew Meyer, Bora Lim, James P. Barrish, Weston Porter, Kourosh Zarringhalam, Philip L. Lorenzi, Gloria V. Echeverria. Mitochondrial structure and function adaptation in residual triple negative breast cancer cells surviving chemotherapy treatment [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-11-14.

Mitochondrial structure and function adaptation in residual triple negative breast cancer cells surviving chemotherapy treatment

Neoadjuvant chemotherapy (NACT) used for triple negative breast cancer (TNBC) eradicates tumors in ~45% of patients. Unfortunately, TNBC patients with substantial residual cancer burden have poor metastasis free and overall survival rates. We previously demonstrated mitochondrial oxidative phosphorylation (OXPHOS) was elevated and was a unique therapeutic dependency of residual TNBC cells surviving NACT. We sought to investigate the mechanism underlying this enhanced reliance on mitochondrial metabolism. Mitochondria are morphologically plastic organelles that cycle between fission and fusion to maintain mitochondrial integrity and metabolic homeostasis. The functional impact of mitochondrial structure on metabolic output is highly context dependent. Several chemotherapy agents are conventionally used for neoadjuvant treatment of TNBC patients. Upon comparing mitochondrial effects of conventional chemotherapies, we found that DNA-damaging agents increased mitochondrial elongation, mitochondrial content, flux of glucose through the TCA cycle, and OXPHOS, whereas taxanes instead decreased mitochondrial elongation and OXPHOS. The mitochondrial effects of DNA-damaging chemotherapies were dependent on the mitochondrial inner membrane fusion protein optic atrophy 1 (OPA1). Further, we observed heightened OXPHOS, OPA1 protein levels, and mitochondrial elongation in an orthotopic patient-derived xenograft (PDX) model of residual TNBC. Pharmacologic or genetic disruption of mitochondrial fusion and fission resulted in decreased or increased OXPHOS, respectively, revealing longer mitochondria favor oxphos in TNBC cells. Using TNBC cell lines and an in vivo PDX model of residual TNBC, we found that sequential treatment with DNA-damaging chemotherapy, thus inducing mitochondrial fusion and OXPHOS, followed by MYLS22, a specific inhibitor of OPA1, was able to suppress mitochondrial fusion and OXPHOS and significantly inhibit regrowth of residual tumor cells. Our data suggest that TNBC mitochondria can optimize OXPHOS through OPA1-mediated mitochondrial fusion. These findings may provide an opportunity to overcome mitochondrial adaptations of chemoresistant TNBC.

Interfering with lipid metabolism through targeting CES1 sensitizes hepatocellular carcinoma for chemotherapy

Hepatocellular carcinoma (HCC) is the most common lethal form of liver cancer. Apart from surgical removal and transplantation, other treatments have not yet been well established for patients with HCC. In this study, we found that carboxylesterase 1 (CES1) is expressed at various levels in HCC. We further revealed that blockage of CES1 by pharmacological and genetical approaches leads to altered lipid profiles that are directly linked to impaired mitochondrial function. Mechanistically, lipidomic analyses indicated that lipid signaling molecules, including polyunsaturated fatty acids (PUFAs), which activate PPARα/γ, were dramatically reduced upon CES1 inhibition. As a result, the expression of SCD, a PPARα/γ target gene involved in tumor progression and chemoresistance, was significantly downregulated. Clinical analysis demonstrated a strong correlation between the protein levels of CES1 and SCD in HCC. Interference with lipid signaling by targeting the CES1-PPARα/γ-SCD axis sensitized HCC cells to cisplatin treatment. As a result, the growth of HCC xenograft tumors in NU/J mice was potently slowed by coadministration of cisplatin and CES1 inhibition. Our results, thus, suggest that CES1 is a promising therapeutic target for HCC treatment.

Comparison of Risk Factors and Angiographic Profile between Younger and Older Patients with Acute Myocardial Infarction

Acute myocardial infarction (AMI) in younger adults (≤40 years) is being increasingly encountered in recent years among the South Asian population. Data regarding the presentation, risk factors and angiographic findings on this important subset of patients is lacking in our country. The aim of this study was to compare the risk factors and pattern of Coronary artery involvement in younger patients presenting with AMI with that of the older age group. This was a cross-sectional observational study conducted during the period from October 2018 to June 2019. Seventy consecutive AMI patients age ≤40 years and another 70 consecutive AMI patients age >40 years undergoing Coronary Angiogram (CAG) were included in the study. After taking informed written consent; demographic, anthropometric, risk factors, CAG findings were recorded in a pre-designed case record form. The severity of Coronary Artery Disease (CAD) was calculated by using Gensini score. The mean age of the younger and older patient groups was 36.89±4.4 years and 57.00±8.4 years respectively. Among the risk factors, smoking (67.1% versus 45.7%, p=0.017), positive family history CAD (38.6% versus 22.9%, p=0.040) and obesity (34.3% versus 20.0%, p= 0.05) were more common in younger group. Whereas, Hypertension (41.4% versus 72.9%, p=0.010) and DM (28.6% versus 50.0%, p=0.024) were more common in older patients. Younger patients mainly presented with STEMI (60.0% versus 48.6%) and predominantly had single vessel disease (42.9%), whereas older patients readily presented with NSTEMI (51.4%) and had a higher incidence of double vessel disease (32.9%) and triple vessel disease (30.0%). The Median Gensini score was significantly higher among the older patients than in the younger age group. Patients in younger age group showed a different pattern of risk factors and coronary artery involvement in comparison to the older age group. Thus, offering younger individuals to make them aware of these risk factors and their early detection, as well as an effective intervention may help to prevent AMI in younger people.

Thymidylate synthase accelerates Men1-mediated pancreatic tumor progression and reduces survival

Clinical studies of cancer patients have shown that overexpression or amplification of thymidylate synthase (TS) correlates with a worse clinical outcome. We previously showed that elevated TS exhibits properties of an oncogene and promotes pancreatic neuroendocrine tumors (PanNETs) with a long latency. To study the causal impact of elevated TS levels in PanNETs, we generated a mouse model with elevated human TS (hTS) and conditional inactivation of the Men1 gene in pancreatic islet cells (hTS/Men1^–/–). We demonstrated that increased hTS expression was associated with earlier tumor onset and accelerated PanNET development in comparison with control Men1^–/– and Men1^+/ΔN3-8 mice. We also observed a decrease in overall survival of hTS/Men1^+/– and hTS/Men1^–/– mice as compared with control mice. We showed that elevated hTS in Men1-deleted tumor cells enhanced cell proliferation, deregulated cell cycle kinetics, and was associated with a higher frequency of somatic mutations, DNA damage, and genomic instability. In addition, we analyzed the survival of 88 patients with PanNETs and observed that high TS protein expression independently predicted worse clinical outcomes. In summary, elevated hTS directly participates in promoting PanNET tumorigenesis with reduced survival in Men1-mutant background. This work will refocus attention on new strategies to inhibit TS activity for PanNET treatment.

Sensitization of FOLFOX-resistant colorectal cancer cells via the modulation of a novel pathway involving protein phosphatase 2A

The treatment of colorectal cancer (CRC) with FOLFOX shows some efficacy, but these tumors quickly develop resistance to this treatment. We have observed increased phosphorylation of AKT1/mTOR/4EBP1 and levels of p21 in FOLFOX-resistant CRC cells. We have identified a small molecule, NSC49L, that stimulates protein phosphatase 2A (PP2A) activity, downregulates the AKT1/mTOR/4EBP1-axis, and inhibits p21 translation. We have provided evidence that NSC49L- and TRAIL-mediated sensitization is synergistically induced in p21-knockdown CRC cells, which is reversed in p21-overexpressing cells. p21 binds with procaspase 3 and prevents the activation of caspase 3. We have shown that TRAIL induces apoptosis through the activation of caspase 3 by NSC49L-mediated downregulation of p21 translation, and thereby cleavage of procaspase 3 into caspase 3. NSC49L does not affect global protein synthesis. These studies provide a mechanistic understanding of NSC49L as a PP2A agonist, and how its combination with TRAIL sensitizes FOLFOX-resistant CRC cells.

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A PP2A agonist has been identified that sensitizes FOLFOX-resistant CRC cells

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It downregulates AKT1/mTOR/4EBP1 axis and p21 translation

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Describes a link between p21 and procaspase 3 in TRAIL-resistance

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Downregulation of p21 synergistically induces TRAIL-mediated apoptosis

Abstract LB138: DAXX interacts with sterol regulatory element-binding proteins (SREBPs) to promote oncogenic lipogenesis and tumorigenesis in triple-negative breast cancer

Elevated lipid metabolism including lipogenesis is a major metabolic feature in cancer cells. In breast and other cancer types, genes involved in lipogenesis are highly upregulated, but the mechanisms that control their expression remain poorly understood. DAXX modulates gene expression through binding to numerous transcription factors although the functional impact of these diverse interactions remains to be defined. Our recent analysis indicates that DAXX is overexpressed in diverse cancer types and metastases. However, mechanisms underlying DAXX’s oncogenic function remains elusive. Using global integrated transcriptomic and lipidomic analyses, we show that DAXX plays a key role in lipid metabolism in triple-negative breast cancer (TNBC) cells. DAXX depletion attenuates, while its overexpression enhances, lipogenic gene expression, lipid synthesis and tumor growth. Mechanistically, DAXX interacts with SREBP1 and SREBP2 and activates SREBP-mediated transcription. DAXX associates with lipogenic gene promoters through SREBPs. Underscoring the critical roles for the DAXX-SREBP interaction for lipogenesis, SREBP2 knockdown attenuates tumor growth in cells with DAXX overexpression, and a DAXX mutant unable to bind SREBPs are incapable of promoting lipogenesis and tumor growth. In TNBC patients, DAXX expression levels are increased in breast cancer brain metastasis and correlate with poor patient survival. Our results identify the DAXX-SREBP axis as an important pathway for tumorigenesis in TNBC. (This work is supported by Florida Department of Health Grants.)

Citation Format: Iqbal Mahmud, Guimei Tian, Tarun Hutchison, Brandon Kim, Daiqing Liao. DAXX interacts with sterol regulatory element-binding proteins (SREBPs) to promote oncogenic lipogenesis and tumorigenesis in triple-negative breast 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 LB138.

Calcium/Calmodulin-Dependent Protein Kinase Kinase 2 Regulates Hepatic Fuel Metabolism

Objective

The liver is the primary internal metabolic organ that coordinates whole body energy homeostasis in response to feeding and fasting. Genetic ablation or pharmacological inhibition of calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) has been shown to significantly improve hepatic health and peripheral insulin sensitivity upon overnutrition with high fat diet. However, the precise molecular underpinnings that explain this metabolic protection have remained largely undefined.

Methods

To characterize the role of CaMKK2 in hepatic metabolism, we developed and challenged liver-specific CaMKK2 knockout (CaMKK2^LKO) mice with high fat diet and performed glucose and insulin tolerance tests to evaluate peripheral insulin sensitivity. We used a combination of RNA-Sequencing, glucose and fatty acid istotopic tracer studies, a newly developed Seahorse assay for measuring the oxidative capacity of purified peroxisomes, and a degenerate peptide libarary to identify putative CaMKK2 substrates that mechanistically explain the protective effects of hepatic CaMKK2 ablation.

Results

Consistent with previous findings, we show that hepatic CaMKK2 ablation significantly improves indices of peripheral insulin sensitivity. Mechanistically, we found that CaMKK2 phosphorylates and regulates GAPDH to promote glucose metabolism and PEX3 to blunt peroxisomal fatty acid catabolism in the liver.

Conclusion

CaMKK2 is a central metabolic fuel sensor in the liver that significantly contributes to whole body systems metabolism.

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Hepatic CaMKK2 is sufficient to toggle peripheral insulin sensitivity.

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CaMKK2 is required for hepatic glucose metabolism.

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Hepatic CaMKK2 balances glycolytic and fatty acid metabolism.

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CaMKK2 promotes glycolysis through regulation of GAPDH.

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CaMKK2 suppresses fatty acid metabolism through Pex3.

Lipogenesis mediated by OGR1 regulates metabolic adaptation to acid stress in cancer cells via autophagy

Malignant tumors exhibit altered metabolism resulting in a highly acidic extracellular microenvironment. Here, we show that cytoplasmic lipid droplet (LD) accumulation, indicative of a lipogenic phenotype, is a cellular adaption to extracellular acidity. LD marker PLIN2 is strongly associated with poor overall survival in breast cancer patients. Acid-induced LD accumulation is triggered by activation of the acid-sensing G-protein-coupled receptor (GPCR) OGR1, which is expressed highly in breast tumors. OGR1 depletion inhibits acid-induced lipid accumulation, while activation by a synthetic agonist triggers LD formation. Inhibition of OGR1 downstream signaling abrogates the lipogenic phenotype, which can be rescued with OGR1 ectopic expression. OGR1-depleted cells show growth inhibition under acidic growth conditions in vitro and tumor formation in vivo. Isotope tracing shows that the source of lipid precursors is primarily autophagy-derived ketogenic amino acids. OGR1-depleted cells are defective in endoplasmic reticulum stress response and autophagy and hence fail to accumulate LDs affecting survival under acidic stress.

Pharmacological Inhibition of CBP/p300 Blocks Estrogen Receptor Alpha (ERα) Function through Suppressing Enhancer H3K27 Acetylation in Luminal Breast Cancer

Estrogen receptor alpha (ER) is the oncogenic driver for ER+ breast cancer (BC). ER antagonists are the standard-of-care treatment for ER+ BC; however, primary and acquired resistance to these agents is common. CBP and p300 are critical ER co-activators and their acetyltransferase (KAT) domain and acetyl-lysine binding bromodomain (BD) represent tractable drug targets, but whether CBP/p300 inhibitors can effectively suppress ER signaling remains unclear. We report that the CBP/p300 KAT inhibitor A-485 and the BD inhibitor GNE-049 downregulate ER, attenuate estrogen-induced c-Myc and Cyclin D1 expression, and inhibit growth of ER+ BC cells through inducing senescence. Microarray and RNA-seq analysis demonstrates that A-485 or EP300 (encoding p300) knockdown globally inhibits expression of estrogen-regulated genes, confirming that ER inhibition is an on-target effect of A-485. Using ChIP-seq, we report that A-485 suppresses H3K27 acetylation in the enhancers of ER target genes (including MYC and CCND1) and this correlates with their decreased expression, providing a mechanism underlying how CBP/p300 inhibition downregulates ER gene network. Together, our results provide a preclinical proof-of-concept that CBP/p300 represent promising therapeutic targets in ER+ BC for inhibiting ER signaling.

Rapid Diagnosis of Prostate Cancer Disease Progression Using Paper Spray Ionization Mass Spectrometry

The limitation of prostate specific antigen (PSA) for prostate cancer (PC) diagnosis is well-recognized. The Gleason score (GS) has been the most widely used grading system for prostate tumor differentiation and represents the best-established prognostic indicator for prostate cancer progression. However, a rapid and sensitive noninvasive diagnostic marker that differentiates GS-based prostate cancer disease progression is needed. As PC is becoming a leading cause of cancer related death for men in the U.S. and worldwide, an immediate need exists for an improved, sensitive, noninvasive, and rapid diagnostic test for PC screening. Here, we employed paper spray ionization-mass spectrometry (PSI MS)-based global metabolomics of urine liquid biopsies to distinguish between healthy (negative for any prostate specific health problems) and progressive PC states (low grade PC such as GS6 and high-grade PC such as GS7, GS8, and GS9). For PSI-MS-based direct untargeted metabolic investigation, a raw urine sample was directly pipetted onto a triangular paper substrate, without any additional sample preparation. Multivariate statistical analysis revealed distinct GS-specific metabolic signatures compared to a healthy control. Variable importance in projection from partial least-squares-discriminant analysis showed distinct metabolic patterns that were correlatively elevated with progressive disease and could serve as biomarkers for diagnosis of prostate cancer risk categorization.

Obesity-Dependent Adipokine Chemerin Suppresses Fatty Acid Oxidation to Confer Ferroptosis Resistance

Clear cell renal cell carcinoma (ccRCC) is characterized by accumulation of neutral lipids and adipogenic transdifferentiation. We assessed adipokine expression in ccRCC and found that tumor tissues and patient plasma exhibit obesity-dependent elevations of the adipokine chemerin. Attenuation of chemerin by several approaches led to significant reduction in lipid deposition and impairment of tumor cell growth in vitro and in vivo. A multi-omics approach revealed that chemerin suppresses fatty acid oxidation, preventing ferroptosis, and maintains fatty acid levels that activate hypoxia-inducible factor 2α expression. The lipid coenzyme Q and mitochondrial complex IV, whose biogeneses are lipid-dependent, were found to be decreased after chemerin inhibition, contributing to lipid reactive oxygen species production. Monoclonal antibody targeting chemerin led to reduced lipid storage and diminished tumor growth, demonstrating translational potential of chemerin inhibition. Collectively, the results suggest that obesity and tumor cells contribute to ccRCC through the expression of chemerin, which is indispensable in ccRCC biology. SIGNIFICANCE: Identification of a hypoxia-inducible factor-dependent adipokine that prevents fatty acid oxidation and causes escape from ferroptosis highlights a critical metabolic dependency unique in the clear cell subtype of kidney cancer. Targeting lipid metabolism via inhibition of a soluble factor is a promising pharmacologic approach to expand therapeutic strategies for patients with ccRCC.See related commentary by Reznik et al., p. 1879.This article is highlighted in the In This Issue feature, p. 1861.

Mass Spectrometry Techniques in Emerging Pathogens Studies: COVID-19 Perspectives

As corona virus disease 2019 (COVID-19) is a rapidly growing public health crisis across the world, our knowledge of meaningful diagnostic tests and treatment for severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is still evolving. This novel coronavirus disease COVID-19 can be diagnosed using RT-PCR, but inadequate access to reagents, equipment, and a nonspecific target has slowed disease detection and management. Precision medicine, individualized patient care, requires suitable diagnostics approaches to tackle the challenging aspects of viral outbreaks where many tests are needed in a rapid and deployable approach. Mass spectrometry (MS)-based technologies such as proteomics, glycomics, lipidomics, and metabolomics have been applied in disease outbreaks for identification of infectious disease agents such as virus and bacteria and the molecular phenomena associated with pathogenesis. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) is widely used in clinical diagnostics in the United States and Europe for bacterial pathogen identification. Paper spray ionization mass spectrometry (PSI-MS), a rapid ambient MS technique, has recently open a new opportunity for future clinical investigation to diagnose pathogens. Ultra-high-pressure liquid chromatography coupled high-resolution mass spectrometry (UHPLC-HRMS)-based metabolomics and lipidomics have been employed in large-scale biomedical research to discriminate infectious pathogens and uncover biomarkers associated with pathogenesis. PCR-MS has emerged as a new technology with the capability to directly identify known pathogens from the clinical specimens and the potential to identify genetic evidence of undiscovered pathogens. Moreover, miniaturized MS offers possible applications with relatively fast, highly sensitive, and potentially portable ways to analyze for viral compounds. However, beneficial aspects of these rapidly growing MS technologies in pandemics like COVID-19 outbreaks has been limited. Hence, this perspective gives a brief of the existing knowledge, current challenges, and opportunities for MS-based techniques as a promising avenue in studying emerging pathogen outbreaks such as COVID-19.

Global Metabolomics in Allogeneic Hematopoietic Cell Transplantation Recipients Discordant for Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) remains a significant late effect issue for allogeneic hematopoietic cell transplantation (allo-HCT) survivors, contributing to morbidity and mortality. The etiology of cGVHD is not well elucidated. Owing to a lack of early diagnostic tests and pathophysiology ambiguity, targeted treatments remain limited. Biomarkers for prediction, control response, or prognostication have not yet been identified. Metabolomics, the quantification of metabolites, is a potential biomarker of cGVHD but has not been evaluated in this population. In this study, we examined global metabolites of stored plasma to identify differentially expressed metabolites of individuals discordant for cGVHD following allo-HCT. A descriptive, comparative, cross-sectional study design was used to examine differentially expressed metabolites of plasma samples obtained from 40 adult allo-HCT recipients (20 with cGVHD and 20 without cGVHD) from 2 parent studies. Metabolomics profiling was conducted at the University of Florida's Southeast Center for Integrative Metabolomics. Full experimental methods followed a previously published method. All statistical analyses were performed by a PhD-prepared, trained bioinformatics statistician. There were 10 differentially expressed metabolites between participants with cGVHD and those without cGVHD. Differential metabolites included those related to energy metabolism (n = 3), amino acid metabolism (n = 3), lipid metabolism (n = 2), caffeine metabolism (n = 1), and neurotransmission (n = 1). Serotonin had the greatest fold change (21.01). This study suggests that cGVHD may be associated with expanded cellular energy and potentially mitochondrial dysfunction. The differential metabolic profile between patients with and without cGVHD indicates metabolic perturbations that merit further exploration as potential biomarkers of cGVHD. These findings support the need for further examination using a larger, prospective study design to identify metabolomic risk factors that may signal the need for earlier preventive measures and earlier treatment to reduce cGVHD.

Predictive Value of Waist Height Ratio, Waist Hip Ratio and Body Mass Index in Assessing Angiographic Severity of Coronary Artery Disease in Myocardial Infarction Patients

Coronary artery disease (CAD) is the leading cause of mortality and morbidity both in developed and developing countries. The body mass index (BMI), waist hip ratio (WHR) and waist height ratio (WHtR) are some of the clinical tools enabling clinicians to assess obesity. Although for decades there have been controversy regarding the relationship between obesity and CAD; it has been assumed that high BMI is a risk factor for CAD. However, the findings of some recent studies were paradoxical. The aim of this study was to identify the best tool among BMI, WHtR and WHR to evaluate angiographically severe CAD in myocardial infarction patients. This was a cross-sectional analytical study carried out in the Department of Cardiology, Chattogram Medical College and Hospital (CMCH), Chattogram, Bangladesh from January 2017 to December 2017. Three hundred and thirty two consecutive MI patients undergoing CAG during the study period were included in the study as per inclusion and exclusion criteria. Severity of CAD was calculated by using Gensini score. Patients were categorized and compared according to anthropometric indices and CAD severity. The mean±SD of the age of study population was 53.62±10.36 years (range 25-92) and 276(83.1%) were male. Regarding cardiovascular risk factors, 113(34%) patients had diabetes mellitus, 108(32.5%) had dyslipidaemia, 137(41.3%) had hypertension, 205(61.7%) were current or ex-smokers and 59(17.8%) had a family history of CAD. The mean±SD of the patients' BMI was 24.05±3.24kg/m² (range 16.14-32.72), mean±SD of their WHR was 0.964±0.052 (range 0.823-1.125) and mean±SD of their WHtR was 0.546±0.059 (range 0.389-0.748). The mean±SD of the severity of CAD according to the Gensini score was 41.11±28.66 (ranged from 2 to 244). Study findings showed a positive correlation between the severity of CAD with WHtR and WHR but not with BMI, according to Gensini scores (p=0.004, p=0.023 and p=0.43 respectively). Receiver Operating Characteristics (ROC) curve analysis revealed that waist height ratio had the highest area under the curve (AUC) among the three anthropometric parameters for predicting presence of severe CAD. Study showed the superiority of WHtR over WHR and BMI for predicting angiographic severity of CAD in patients with MI. WHtR should therefore be considered as a screening tool.

SHadow Under the Lamp (SHUL): Smoking behavior of the health professionals

Background

Smoking cessation is the best option a health professional can offer to the patients for averting the preventable causes of mortality and morbidity.

Purpose

To determine smoking behavior, preferred cessation methods, and attitudes towards smoking cessation amongst health professionals.

Methods

The cross-sectional study, conducted in six countries, included doctors and nurses working at different hospital settings. Participants responded anonymously to an online questionnaire.

Results

Among 1109 participants, 36% were from Saudi Arabia, 14% from Nepal, 14% from Indonesia, 12% from Australia, 12% from Jordan, and 12% from Pakistan. Mean age was 33 years, 61% were females and 58% were nurses. One in eight (12%) was daily smoker. Among current smokers, 42% smoked 2-9 cigarettes/day, and 26% had their first cigarette within 5-30 minutes after waking up. Half of the smokers perceived it as 'very important' to quit smoking, 30% had tried to quit in the last six months, and 31% preferred to have a group quit program with the same health professionals. Only 17% had formal training on smoking cessation, but 57% were interested to receive one. Half of the participants said they (53%) 'always' asked patients if they smoked, but 89% said they advised to quit, 76% said they assessed intention to quit, 28% said they assisted by providing materials on cessation, and 33% said they arranged follow up for cessation. Compared to current smokers, never smokers were more likely to 'always' ask patients if they smoked (78% vs. 22%, p = 0.044, ORs 1.39, 95%CIs 1.01-1.91), assist smokers by setting quit dates (74% vs. 26%, p = 0.039, ORs 1.54, 95%CIs 1.03-2.29), arrange follow up (77% vs. 23%, p = 0.044, ORs 1.40, 95%CIs 1.01-1.94).

Conclusions

Health professionals reported moderately good behavior around advice to smokers, but it is much worse among current smokers. Health professionals who smoke should be both encouraged to quit and to better support their patients to do so.

Key messages

Smoking cessation support for patients was not good among health professionals, who were smokers. Health professionals need to quit smoking in order to provide better cessation support for patients.

Abstract 2562: Causes and consequences of adiposomogenesis in breast cancer cells

Malignant tumors exhibit altered metabolism resulting in a highly acidic extracellular microenvironment. Adaptation to acidic conditions is a pre-requisite for tumor cells to survive and thrive and to out-compete the stroma into which they invade. Acid adaptation has been associated with chronic activation of autophagy and redistribution of the lysosomal proteins to the plasma membrane. In addition to these survival mechanisms, tumor cells under acidic conditions accumulate cytoplasmic lipid droplets (adiposomes); dynamic organelles that store neutral lipids surrounded by a shell of perilipin (PLIN) proteins and a phospholipid monolayer. Adiposomes are dynamic organelles that store neutral lipids surrounded by a shell of proteins (PLIN2) and a phospholipid monolayer. High expression of PLIN2 was observed to be strongly associated with poor overall survival in breast cancer patients. In vitro, breast cancer cells rapidly and robustly accumulated adiposomes when grown in acidic media revealed by nile red and PLIN-2 staining. The acid-induced lipogenic phenotype persists even when the cells are grown in de-lipidated serum, indicating that the source of lipids is de-novo and endogenous. Adiposome formation at low pH was attenuated when cells were treated with inhibitors of fatty acid synthesis, FAS; such as TOFA or C75. Further, these inhibitors were selectively cytotoxic under acidic conditions indicating that adiposomogenesis is a survival mechanism. Consistent with increased FAS we also observed using 13C isotopomer analysis a major shift in glucose metabolism from Embden Meyerhof to the Pentose Phosphate Pathway, which results in increased production of NADPH, necessary for de novo lipid synthesis. In addition, we observed that cells at low pH had higher rates of oxygen consumption (OCR) compared to controls using Seahorse profiling. The major source of the lipid precursors was identified to be autophagy-derived ketogenic amino acids using LC-LS/MS following 13C tracer pre-incubation. Further, we tested the hypothesis that adiposomogenesis is induced by acid signal and this signaling is mediated by one (or more) acid sensing G-protein coupled receptors. Both OGR1 and TDAG8 were strongly expressed in our systems. CRISPR/Cas9 mediated depletion of these receptors showed that TDAG8 KO had no effect, but that KO of OGR1 abrogated adiposome accumulation under acidic conditions in MCF7 and T47D cells. Further, OGR1 knockout cells were defective in acid induced autophagy. In xenograft models, OGR1 knockout MCF7 cells formed significantly smaller tumors compared to control cells. Hence, accumulation of adiposomes is a highly regulated process related to storing autophagic products, and appears to be important in cell survival in acid stress. This increased dependence on lipid metabolism revealed novel therapeutic vulnerabilities

Citation Format: Smitha R. Pillai, Iqbal Mahmud, Michael Langsen, Jonathan Wojtkowiak, Jonathan Nguyen, Marylin Bui, Robert Gatenby, Timothy Garrett, Robert Gillies. Causes and consequences of adiposomogenesis in breast cancer cells [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 2562.

Abstract 4669: Pharmacologic inhibition of CBP/p300 suppresses estrogen-induced gene expression and proliferation in ER+ luminal breast cancer cells

Luminal breast cancer, defined by the expression of the estrogen receptor alpha (ERα), comprises nearly two thirds of all breast cancer cases and most patients with breast cancer die of this subtype. ERα is a steroid nuclear receptor that functions as a transcription factor to upregulate genes such as MYC that are involved in cell cycle progression. Antagonists of ERα are the standard of care treatment for ER+ luminal breast cancer, but resistance to these antagonists in advanced patients is a major clinical issue. Therefore, there is an unmet medical need to develop more effective therapies for treating ER+ breast cancer. CBP/p300 are two paralogous acetyltransferases that catalyze histone acetylation at enhancers and promoters to activate gene expression. They serve as transcriptional co-activators for several oncogenic signaling pathways, including the pro-growth androgen and estrogen signaling pathways in cancer. Due to their emerging role in promoting tumor growth, the oncogenic functions of CBP/p300 and means of their pharmacologic inhibition are under intense investigation for developing potential therapeutics for cancer treatment. CBP/p300's acetyltransferase (HAT) domain and their bromodomain represent tractable drug targets and potent and specific small molecule inhibitors have been developed for both. However, the pharmacologic effects and anticancer efficacy of these compounds in breast cancer remain largely unexplored. Previous research shows that CBP/p300 serve as co-activators for ERα and are responsible for catalyzing Histone 3, lysine 18 and 27 acetylation (H3K18ac and H3K27ac) at ERα target genes. We hypothesize that CBP/p300 are critical for ERα function in driving oncogene expression and their pharmacologic inhibition will block ERα-mediated gene expression underpinning the tumor growth of luminal breast cancer. In support of our hypothesis, we report that small molecule inhibitors of the CBP/p300 HAT domain and bromodomain strongly inhibit estrogen- induced MYC expression and prevent colony formation in vitro of a panel of ER+ cell lines. Furthermore, inhibition of CBP/p300 also downregulates ERα activity in a luciferase assay using a construct driven by the conical ERα-binding DNA sequence. H3K27ac ChIP-seq data in the ER+ luminal breast cancer MCF-7 cells indicate that pharmacologic inhibition of CBP/p300 catalytic function blocks specific enhancer function. Our study suggests pharmacologically targeting CBP/p300 may be an effective strategy for treating luminal breast cancer. (Supported by James and Esther King Biomedical Research Program, and Bankhead-Coley Cancer Research Program, Florida Department of Health)

Citation Format: Aaron Richard Waddell, Iqbal Mahmud, Zhiguang Huo, Daiqing Liao. Pharmacologic inhibition of CBP/p300 suppresses estrogen-induced gene expression and proliferation in ER+ luminal breast cancer cells [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 4669.

Exploring Associations Between Metabolites and Symptoms of Fatigue, Depression and Pain in Women With Fibromyalgia

Fibromyalgia (FM) is a chronic noncommunicable disorder characterized by a constellation of symptoms that include fatigue, depression and chronic pain. FM affects 2%-8% of the U.S. population, 2% of the global population, with 61%-90% of FM diagnoses attributed to women. Key causal factors leading to the development and severity of FM-related symptoms have not yet been identified. The purpose of this article is to report relationships among identified metabolites and levels of fatigue, depression, pain severity, and pain interference in a sample of 20 women with FM. In this secondary analysis, we conducted global metabolomic analysis and examined the data for relationships of metabolite levels with self-reported symptoms of fatigue, depression, pain severity, and pain interference. Results revealed six metabolites (6-deoxy-hexose; pantothenic acid; ergothioneine; l-carnitine; n-acetylserotonin; butyrobetaine) and their associated metabolic pathways such as carnitine synthesis, lipid oxidation, tryptophan metabolism, beta-alanine metabolism and pantothenic and Coenzyme-A biosynthesis that were either positively or inversely related to pain severity, pain interference, or both. The preliminary data presented suggest that metabolites representing energy, amino acid, or lipid classification may be associated with pain symptom severity and interference in women with FM. Future work will confirm these findings in a large, comparative cohort, targeting metabolites and metabolite pathways to better understand the relationships of metabolites and symptomology.

Rapid Prostate Cancer Noninvasive Biomarker Screening Using Segmented Flow Mass Spectrometry-Based Untargeted Metabolomics

Spectrometric methods with rapid biomarker detection capacity through untargeted metabolomics are becoming essential in the clinical cancer research. Liquid chromatography-mass spectrometry (LC-MS) is a rapidly developing metabolomic-based biomarker technique due to its high sensitivity, reproducibility, and separation efficiency. However, its translation to clinical diagnostics is often limited due to long data acquisition times (∼20 min/sample) and laborious sample extraction procedures when employed for large-scale metabolomics studies. Here, we developed a segmented flow approach coupled with high-resolution mass spectrometry (SF-HRMS) for untargeted metabolomics, which has the capability to acquire data in less than 1.5 min/sample with robustness and reproducibility relative to LC-HRMS. The SF-HRMS results demonstrate the capability for screening metabolite-based urinary biomarkers associated with prostate cancer (PCa). The study shows that SF-HRMS-based global metabolomics has the potential to evolve into a rapid biomarker screening tool for clinical research.

DAXX in cancer: phenomena, processes, mechanisms and regulation

DAXX displays complex biological functions. Remarkably, DAXX overexpression is a common feature in diverse cancers, which correlates with tumorigenesis, disease progression and treatment resistance. Structurally, DAXX is modular with an N-terminal helical bundle, a docking site for many DAXX interactors (e.g. p53 and ATRX). DAXX's central region folds with the H3.3/H4 dimer, providing a H3.3-specific chaperoning function. DAXX has two functionally critical SUMO-interacting motifs. These modules are connected by disordered regions. DAXX's structural features provide a framework for deciphering how DAXX mechanistically imparts its functions and how its activity is regulated. DAXX modulates transcription through binding to transcription factors, epigenetic modifiers, and chromatin remodelers. DAXX's localization in the PML nuclear bodies also plays roles in transcriptional regulation. DAXX-regulated genes are likely important effectors of its biological functions. Deposition of H3.3 and its interactions with epigenetic modifiers are likely key events for DAXX to regulate transcription, DNA repair, and viral infection. Interactions between DAXX and its partners directly impact apoptosis and cell signaling. DAXX's activity is regulated by posttranslational modifications and ubiquitin-dependent degradation. Notably, the tumor suppressor SPOP promotes DAXX degradation in phase-separated droplets. We summarize here our current understanding of DAXX's complex functions with a focus on how it promotes oncogenesis.

Decoding the Metabolome and Lipidome of Child Malnutrition by Mass Spectrometric Techniques: Present Status and Future Perspectives

Child malnutrition (CM) is a global public health problem. It contributes to poor health in one in four children under five years worldwide and causes serious health problems in children, including stunted, wasted, and overweight growth. These serious public health issues lead to a higher chance of living in poverty in adulthood. Malnutrition is related with reduced economic productivity and increases the serious national and international burden. Currently, there is no meaningful therapeutic intervention of CM, and the use of different therapeutic foods has shown poor outcomes among supplemented malnourished children. The role of metabolites and lipids has been extensively recognized as early determinants of child health, but their contribution in CM and its pathobiology are poorly understood. This perspective provides a most recent update on these aspects. After briefly introducing the disciplines of metabolomics and lipidomics, we describe a mass spectrometry-based metabolic workflow for analysis of both metabolites and lipids and summarize several recent applications of metabolomics and lipidomics in CM. Finally, we discuss the future directions of the field toward the development of meaningful interventions for CM through metabolomics and lipidomics advances.

Abstract 5214: Targeting the estrogen receptor pathway in luminal breast cancer through inhibition of p300/CBP

Luminal breast cancer represents approximately two thirds of all breast cancer cases and is characterized by the expression of hormone receptors, such as the estrogen receptor alpha (ER). ERα is a member of the steroid nuclear receptor family and is involved in a hormonal signaling pathway that drives tumor growth through upregulation of genes involved in cell cycle progression, such as MYC and CCND1. Antagonists of ER function are the standard of care treatment for ER+ luminal breast cancer. However, resistance to ER antagonists is common in advanced breast cancer cases. Therefore, there is an urgent need to investigate new therapeutics that can be utilized to treat tumors that are resistant to traditional therapies. p300/CBP are two paralogous acetyltransferases that catalyze histone 3, lysine 18 and 27 acetylation (H3K18ac and H3K27ac) at promoters and enhancers to promote gene expression. ER mediated transcription is critically reliant upon the recruitment of co-activators, including p300/CBP. However, the mechanistic role of p300/CBP catalytic activity in globally regulating ER mediated transcription remains poorly understood. Inhibition of p300/CBP, as a critical co-activator of ER, potentially represents an applicable strategy for inhibiting ER function in luminal breast tumors. Importantly, the catalytic histone acetyltransferase (HAT) domain of p300/CBP is under intense investigation as a target of small molecule therapeutics in cancer. We analyzed publicly available data and report that p300/CBP are upregulated at the mRNA level in breast cancer, including the luminal subtypes, and that their expression negatively correlates with patient survival. We also found that pharmacologic inhibition of p300/CBP HAT activity in ER+ cell lines potently suppresses ER mediated transcription, downregulates ER, c-Myc and Cyclin D1 protein levels and prevents estrogen induced growth in vitro. Studies are underway to understand how p300/CBP regulates ER signaling using genetic, pharmacologic, and biochemical methods to assess the therapeutic effects of pharmacologic p300/CBP inhibition on ER+ breast cancer. (Supported by Bankhead-Coley Research Program, and James and Esther King Biomedical Research Program, Florida Department of Health)

Citation Format: Aaron Waddell, Iqbal Mahmud, Guimei Tian, Daiqing Liao. Targeting the estrogen receptor pathway in luminal breast cancer through inhibition of p300/CBP [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5214.

Abstract 4718: SR-4370, a potent and selective inhibitor of class I HDACs, suppresses AR signaling and in vivo prostate tumor growth

Androgen receptor (AR) is an androgen-activated transcription factor and drives prostate cancer (PCa) progression. Class I HDACs 1-3 are critical for activating AR-mediated transcription. Thus, targeting these HDACs is a promising strategy for treating PCa. Notably, along with significant adverse effects, several FDA-approved HDAC inhibitors broadly inhibiting different HDACs were ineffective for treating castration-resistant prostate cancer in clinical trials. Significantly, entinostat, an aminobenzamide analog specific to HDACs 1-3, extended overall survival for patients with breast cancer resistant to endocrine therapy. These observations suggest that HDACi selective to HDACs 1-3 may be effective for treating solid tumors including PCa. We have recently discovered the novel benzoylhydrazide class of HDAC inhibitors highly specific to HDACs 1-3. An optimized analog, SR-4370, exhibited low µM to nM potency against HDACs 1-3. SR-4370 markedly suppressed AR signaling, PCa cell proliferation in vitro, and prostate tumor growth in vivo. Gene expression profiling experiments revealed that SR-4370 downregulated AR, AR-Vs and AR target genes as well as the MYC oncogenic network. Chromatin accessibility assay using ATAC-seq showed that SR-4370 altered chromatin states in PCa cells. The chromatins with AR-binding sites became inaccessible on SR-4730 treatment, indicating that altered chromatin accessibility may contribute to the inhibition of AR signaling. Interestingly, SR-4370 sensitized C4-2 cells to enzalutamide. In PCa xenograft models, SR-4370 was effective to suppress tumor growth in vivo. Importantly, SR-4370 was well tolerated and did not cause observable adverse effects as judged by body weight and blood chemistry tests of treated mice. Our data suggest that SR-4370 may be a safe and clinically applicable treatment for advanced PCa refractory to current frontline treatments. (Supported by UFHealth Cancer Center, Florida Breast Cancer Foundation, James and Esther King Biomedical Research Program, and Bankhead-Coley Cancer Research Program, Florida Department of Health)

Citation Format: Iqbal Mahmud, Guimei Tian, Jia Wang, Ryan Stowe, Zhiguang Huo, Yushan Zhang, Hamsa Thayek Purayil, Eric Helm, Theodore Drashansky, Dorina Avram, Yehia Daaka, William R. Roush, Daiqing Liao. SR-4370, a potent and selective inhibitor of class I HDACs, suppresses AR signaling and in vivo prostate tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4718.

Abstract 2612: Roles of USF1 in breast tumorigenesis and disease progression

Breast cancer accounts for nearly one-quarter of all cancer diagnoses and is the principal cause of cancer-related mortality in women worldwide. Triple negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer commonly resistant to therapeutics that have been successful in increasing survival in patients with ER+, PR+ and HER2+ breast cancer subtypes. As such, identifying factors that contribute to poor patient outcomes and mediate the growth and survival of TNBC cells remain important areas of investigation. USF1 (upstream stimulatory factor 1), a gene linked to drive lipogenesis and cellular proliferation, is overexpressed in human malignancies, yet its contribution to cancer remains unclear. In analyzing large number of genomic datasets including The Cancer Genome Atlas (TCGA), we found that USF1 expression is significantly higher in TNBC patient samples. Also, USF1 gene expression positively correlates with key lipogenic enzymes. Significantly, we found that high expression of USF1 in breast cancer correlates with decreased patient survival. We therefore hypothesize that USF1 promotes breast tumorigenesis and progression by activating lipogenic gene expression. We conducted pilot in vitro studies to determine the influence of USF1 expression and cell proliferation. It was demonstrated that knockdown of USF1 decreased cellular proliferation in 2D cell culture of the TNBC cell line MDA-MB-231. We also assessed the effects on USF1 expression levels on in vivo tumor growth. We found that USF1 overexpression and knockdown enhanced and reduced tumor growth in vivo, respectively. Further studies are underway to determine the mechanisms by which USF1 promotes TNBC tumorigenesis and metastatic progression. Our studies will shed lights on roles of USF1 in breast cancer tumor biology. (Supported by McKnight Foundation, Bankhead-Coley Cancer Research Program and James and Esther King Biomedical Research Program, Florida Department of Health.)

Citation Format: Jessica Lewis, Iqbal Mahmud, Guimei Tian, Daiqing Liao. Roles of USF1 in breast tumorigenesis and disease progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2612.

Abstract 5273: Multi-omics approaches reveal potential role for corticosterone in prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer in American men. In 2018, 164,690 new cancer cases and 29,430 cancer deaths are projected to occur in the United States. Currently, there is no efficient diagnostic and safe treatment option for the management of PCa. Using Ultra-High Performance Liquid Chromatography coupled High Resolution Mass Spectrometry (UHPLC-HRMS), we globally profiled more than 1400 metabolites across 79 urine samples related to PCa (19 control, 23 benign prostate hyperplasia (BPH), 11 prostatitis, and 26 PCa samples). Among all, corticosterone was identified as a top differential metabolite. Corticosterone levels were markedly elevated in PCa urine samples and modest but significant elevation of the corticosterone in BPH and prostatitis urine samples compared to controls, with an excellent area under the receiver operating characteristic curve of 0.95, 0.94, and 0.93, respectively. In addition, the expression of corticosterone biosynthetic gene, Steroid 11-beta-hydroxylase (CYP11B1), was elevated in PCa tissues, cell lines, and urine samples, while Corticosteroid 11-beta-dehydrogenase isozyme 2 (HSD11B2), which metabolize corticosterone, were markedly reduced in prostate tumors. With the understanding that androgen signaling is the key factor for prostate cancer, we investigated the role of androgen in regulating CYP11B1 and HSD11B2. We analyzed several androgen treated PCa cell lines derived global gene expression datasets and revealed that treatment with androgen increase in CYP11B1 expression and a concomitant decrease in HSD11B2 expression levels. Interestingly, we uncover that genetic knockdown of Androgen Receptor (AR) diminished CYP11B1 expression and alternatively, increased HSD11B2. Moreover, AR based chromatin occupancy (ChIP-seq) data also suggest direct binding of AR to the promoter of CYP11B1 in multiple PCa cells. The role of corticosterone in PCa is previously unknown. Our multi-omics approaches thus indicate that corticosterone might be potential prognostic marker for PCa. The tumor biology and mechanism through which corticosterone associates with PCa is being investigated in our laboratory.

Citation Format: Iqbal Mahmud, Bongyong Lee, Ranjan Perera, Timothy J. Garrett. Multi-omics approaches reveal potential role for corticosterone in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5273.

Abstract B004: A combination of two chemically distinct inhibitors of class I HDACs is highly effective to suppress AR signaling and in vivo growth of prostate cancer xenograft

Class I HDACs 1-3 are critical for the AR-mediated transcriptional program. Thus, targeting class I HDACs is a promising strategy for treating prostate cancer. However, several FDA-approved HDAC inhibitors (HDACi) broadly inhibiting different HDACs have been shown to be ineffective and overtly toxic for treating castration-resistant prostate cancer in clinical trials. These observations suggest that HDACi selective for class I HDACs may be more effective but less toxic for treating prostate cancer than pan HDACi. Notably, we and others have shown that HDACi of different chemical classes individually exhibit nonoverlapping but limited effects on the acetylome in cancer cells. We hypothesize that a combination treatment strategy with class I HDAC-selective HDACi of different chemical classes is more effective to block AR signaling and prostate tumor growth than such HDACi individually. We have recently discovered the novel benzoylhydrazide chemo-type of class I HDAC-selective HDACi with a unique pharmacologic profile. Medicinal chemistry effort led to an optimized analog, SR-4370, with 6 nM potency to HDAC3. In support of our hypothesis, SR-4370 in combination with the clinical class I HDACi entinostat markedly suppressed AR signaling, prostate cancer cell proliferation in vitro, and tumor growth in vivo, and the tumor-suppressive effects by the HDACi combination were more pronounced than by SR-4370 and entinostat individually. Gene expression profiling experiments revealed that the SR-4370/entinostat combination profoundly downregulated AR, AR-V7, and AR target genes, while activating immune and cell death signaling pathways. In a C4-2 xenograft model using athymic nude mice, the SR-4370/entinostat combination was highly effective in suppressing tumor growth. Importantly, these HDACi alone or in combination did not cause observable adverse effects judged by body weight and blood chemistry tests of treated mice. Overall, our data suggest that the SR-4370/entinostat combination may be a translatable treatment for castration-resistant prostate cancer.

Citation Format: Guimei Tian, Iqbal Mahmud, Ryan Stowe, Yushan Zhang, Hamsa Thayek Purayil, William Roush, Yehia Daaka, Daiqing Liao. A combination of two chemically distinct inhibitors of class I HDACs is highly effective to suppress AR signaling and in vivo growth of prostate cancer xenograft [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B004.

Abstract LB-248: Chemically distinct class I HDAC inhibitors synergize to inhibit global lipid metabolism in cancer

An increased rate of lipid production is a hallmark metabolic feature in cancer cells, which provides energy supplies, building blocks for membrane biogenesis, and signaling molecules for increased cancer cell proliferation. Current chemotherapeutic strategies targeting lipid metabolism have shown significant limitations, and as such, there is great interest in discovering novel therapies that effectively inhibit lipid production in cancer cells. Class I histone deacetylases (HDACs 1-3) are a key component of the epigenetic machinery regulating gene expression, and behave as oncogenes in several cancer types, spurring the development of HDAC inhibitors (HDACi) as novel anticancer drugs. Interestingly, HDAC inhibitors (HDACi) have been shown to decrease lipid production in different cells by modulating key genes in cholesterol synthesis, uptake, and efflux. However, effects of HDACi in lipid biosynthesis of cancer remains poorly studied. We have discovered a novel class of HDACi with a previously undescribed benzoylhydrazide scaffold. These new inhibitors are highly selective and potent to the class I HDACs (HDAC1, HDAC2, and HDAC3). Using global lipidomics approach by Ultra High-Performance Liquid Chromatography coupled High-Resolution Mass Spectrometry (UHPLC-HRMS), we found that a novel optimized analog, SR-4370, exhibits potent inhibition of lipid production in cells of diverse cancer types. Strikingly, SR-4370 in combination with entinostat, a benzamide analog of class I HDAC inhibitor currently in multiple clinical trials for treating breast cancer and other types of solid tumors, exhibits synergistic effects on inhibition of lipid production in cancer cells. We will present lipidomic profiling data from cells and xenograft tumors after treatment with SR-4370/entinostat, and discuss mechanisms of action for these distinct HDACi in inhibiting lipid production. In summary, our findings provide a rationale for inhibiting lipogenesis using isoform-selective HDACi in cancer therapy.

Citation Format: Iqbal Mahmud, Timothy J. Garrett, Ryan Stowe, William R. Roush, Daiqing Liao. Chemically distinct class I HDAC inhibitors synergize to inhibit global lipid metabolism in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-248.

Abstract 1473: Role of acetyltransferases CBP and p300 in de novo fatty acid synthesis in colorectal cancer

CBP/p300 are two paralogous lysine acetyltransferases that acetylate protein substrates including histones, and serve as transcriptional co-activators for numerous signaling pathways involved in tumorigenesis and cancer progression. Recently, evidence has emerged that p300 regulates the transcription of genes involved in lipogenesis in cancers. Dysregulated lipogenesis and increased de novo production of fatty acids (FA) represent a major metabolic shift in cancer. De novo FA synthesis in cancer is suggested to be a source of lipids for membrane biogenesis, a reservoir of energy, and a source of pro-survival signaling molecules. Therefore, de novo FA synthesis has been linked to survival and increased proliferation of cancer cells, representing a potential area for therapeutic intervention. While emerging evidence indicates CBP/p300 may play a key role in regulating lipogenesis, little is known about the mechanism of how these proteins control lipid production in different cancers. Colorectal cancer (CRC) is a commonly diagnosed human cancer and is a major cause of cancer-related mortality. Key regulators for de novo FA synthesis, such as FASN, have been reported to be elevated in colorectal cancer. We analyzed publically available data sets and report that in colon adenocarcinoma, the mRNA levels of CBP/p300 positively correlate with the expression of genes involved in lipogenesis, such as FASN, SREBP1 and SREBP2. Furthermore, our analysis shows that EP300 expression is negatively correlated with patient survival. Strikingly, our preliminary data suggests that HDAC inhibitors may regulate p300 activity and could serve as a therapeutic approach for suppressing lipogenesis. We are currently utilizing small molecule inhibitors, genetic manipulation of the CREBBP/EP300 genes, and biochemical experiments to investigate the role of CBP/p300 in de novo FA synthesis in colorectal cancer. We hypothesize that inhibition of CBP/p300 could be an attractive therapeutic option for inhibiting tumor growth through downregulating de novo FA synthesis in colorectal cancer. (Supported by grants from James and Esther King Biomedical Research Program and Bankhead-Coly Cancer Research Program, Florida Department of Health.)

Citation Format: Aaron Waddell, Iqbal Mahmud, Daiqing Liao. Role of acetyltransferases CBP and p300 in de novo fatty acid synthesis in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1473.

Abstract 3953: The role of USF1 in the regulation of lipogenesis and breast cancer tumor progression

Breast cancer accounts for nearly one-quarter of all cancer diagnoses and is the principal cause of cancer-related mortality in women worldwide. Triple negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer commonly resistant to therapeutics that have been successful in increasing survival in patients with ER+, PR+ and HER2+ breast cancer subtypes. As such, identifying factors that contribute to poor patient outcomes and mediate the growth and survival of TNBC cells remain important areas of investigation. USF1 (upstream stimulatory factor 1), a gene linked to drive lipogenesis and cellular proliferation, is over-expressed in human malignancies, yet its contribution to cancer remains unclear. In analyzing large number of genomic datasets including The Cancer Genome Atlas (TCGA), we found that USF1 expression is significantly higher in TNBC tumor samples and cell lines. Also, USF1 gene expression positively correlates with key lipogenic enzymes. Significantly, we found that high expression of USF1 in breast cancer correlates with decreased patient survival. We found that USF1 shRNA expression resulted in cell death in breast cancer cell lines. We therefore hypothesize that USF1 drives de novo lipogenesis to promote breast tumorigenesis. Further studies are underway to determine the mechanisms by which USF1 promotes de novo lipogenesis, tumorigenesis and metastatic progression. Our studies will shed lights on the roles of USF1 in breast cancer tumor biology and undercover potential novel anticancer drug targets. (Supported by McKnight Foundation, Bankhead-Coley Cancer Research Program and James and Esther King Biomedical Research Program, Florida Department of Health.)

Citation Format: Jessica Lewis, Iqbal Mahmud, Daiqing Liao. The role of USF1 in the regulation of lipogenesis and breast cancer tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3953.

Abstract LB-312: GRK5 activity mediates in vivo and in vitro prostate cancer progression and chemoresistance

Despite decades of research targeting the activity of the androgen receptor (AR), patients diagnosed with locally advanced and metastatic prostate cancer face an incurable disease. The Daaka lab investigates constituents of G-protein-coupled receptor signaling cascades for their ability to provide mitogenic signaling, which promotes PCa progression. We previously identified G protein-coupled receptor 5 (GRK5) for its ability to regulate PCa progression, independent of AR activity. GRK5 partially partitions to the nucleus, wherein it has been shown to regulate the transcriptome in non-PCa models. To globally elucidate the mechanistic impact of GRK5 on PCa progression, we are investigating the impact of GRK5 on the PCa transcriptome. We hypothesize that GRK5's regulation of the PCa transcriptome promotes tumor progression. To assay the effect of GRK5 on the PCa transcriptome, RNA sequencing was performed in two cell lines: PC3 Control (PC3 shGFP) and PC3 GRK5 Knockdown (PC3 shGRK5).  Ontologic analysis identified the epithelial–mesenchymal transition (EMT) as being affected when GRK5 is depleted. The epithelial–mesenchymal transition (EMT) is highly associated with promoting PCa progression and chemoresistance, thus we selected this pathway for further investigation. Confirmatory western blot analysis and quantitative PCR (qPCR) validated that depleting GRK5 suppresses the expression of the mesenchymal markers Vimentin and N-Cadherin. Similarly, overexpression of GRK5 increases the expression of these mesenchymal markers. Stable overexpression of GRK5 promotes cells to develop a spindle-like morphology, indicative of a mesenchymal state. GRK5 mediates this mesenchymal transition through increasing the expression of the EMT transcription factor, Twist1. Further analysis identifies that GRK5 activity promotes in vitro invasion. Cell lines overexpressing GRK5 demonstrate an increase in resistance to docetaxel, the mainstay chemotherapy for advanced PCa. Overexpression of GRK5 promotes lymphatic intravasation. Overexpression of mutated forms of GRK5 that are relegated to the nucleus are able recapitulated all aforesaid changes, arguing that the nuclear activity of GRK5 mediates this effect. Collectively, this data presents a novel mechanism promoting PCa progression, independent of AR activity.

Citation Format: Joseph B. Black, Hamsa Thayele Purayil, Iqbal Mahmud, Daiqing Liao, Yehia Daaka. GRK5 activity mediates in vivo and in vitro prostate cancer progression and chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-312.