Mark Kester - US grants

1,2-Diacylglycerols (DA) are potent second messengers formed from the receptor-mediated hydrolysis of membrane phospholipids. DA is an essential cofactor for protein kinase C (PKC) activity. PKC phosphorylates a myriad of target proteins that in smooth muscle cell types may be associated, in part, with sustained contraction and proliferation. Preliminary data in rat glomerular mesangial cells suggest that certian receptor-mediated agonists activate phospholipases linked to specific phospholipids. Specifically, regulatory (arginine vasopressin) and pathophysiological (Platelet-activating factor) vasoconstrictor agonists as well as a proinflammatory cytokine (IL-1) generate DRG from distinct phospholipid sources as a function of time. As individual phospholipid species differ in their sn-1 and sn-2 substituents, receptors coupled to specific phospholipase C activities may generate discrete pools of diradyglycerols (DRG) including diacyl-, alkyl,acyl-, or alkenyl, acyl-glycerol species of various chain lengths and degrees of saturation. DRG is a generic term to describe diglycerides composed of undefined long-chain hydrocarbon substituents. The physiology and biochemistry of these unique DRG pools will be the major focus of this proposal. The major hypothesis to be tested postulates that there is a structural correlation between the species of DRG generated and their regulatory function in smooth muscle cell types. The individual molecular species of DRG generated by AVP, PAF or IL-1 will be documented and correlated with their actions on protein kinase C activity. Alter-native roles for these unique DRG pools will be investigated including modulation of DRG-lipase, kinase, and sphingomyelinase activities and potential generation of eicosanoids, phosphatidic acid, and sphingosine, respectively. Thus, discrete DRG molecular species may determine how distinct receptor-mediated agonists induce diverse physiological events through relatively common regulatory signals. The biochemical information contained in individual species of DRG may allow these molecules to function as key branch points in transmembrane signalling.

Activation of ERK and SAPK cascades (subgroups of the mitogen- activated protein kinases, MAPK) culminates in opposing cellular phenotypes. ERKs (extracellular signal-regulated kinase) function as mediators of growth factor- or phorbol ester-induced cellular proliferation; whereas, SAPKs (stress-activated protein kinase) are involved in regulation of cytokine-induced cellular differentiation, apoptosis or growth arrest. Although small molecular weight GYP-binding proteins have been shown to be a common element upstream from both ERK (ras) and SAPK (rac), the understanding of the physiologically relevant second messengers that control or provide specificity for these discrete signaling pathways is not dear. Sphingolipid metabolites have been shown to influence kinases and phosphatases both in intact cell and cell- free systems. Sphingolipid-derivatives also regulate receptor autophosphorylation and receptor-linked small molecular weight GYP- binding proteins. Sphingomyelin, the major membrane sphingolipid 1 can be hydrolyzed to form ceramide and then deacylated to generate sphingosine. Inflammatory cytokine-induced cellular differentiation or apoptosis has been linked to ceramide generation; whereas, growth factor-mediated Cell proliferation has been associated with sphingosine formation. The role of ceramide and sphingosine to differentially regulate ERK and SAPK cascades and to determine. in part, the cellular phenotype has been therefore hypothesized. It is specifically hypothesized that growth factor receptor-induced proliferation may be mediated by sphingosine-regulated ERK bioactivity while cytokine receptors may signal an inflammatory response and/or growth arrest through a ceramide-regulated SAPK cascade. The role of sphingolipid metabolites to differentially regulate ERK and SAPK cascades will be investigated at three levels in rat glomerular mesangial cells: 1) as cofactors for specific kinases or phosphatases; 2) as regulators for small molecular weight GYP-binding proteins; 3) as modulators of receptor/ligand binding kinetics. These studies will establish sphingomyelin derived second messengers as key mediators of cellular proliferation and differentiation via activation of discrete protein kinase cascades.

Signaling mechanisms regulating vascular smooth muscle mitogenesis are being clearly elucidated and exploited for potential therapeutic benefit. To date however, there are still no effective therapeutics designed to control dysregulated vascular smooth muscle proliferation during inflammatory pathologies. Our laboratory is focused on identifying and characterizing endogenous lipid-derived second messengers that inhibit pro-mitogenic signaling cascades regulated through protein kinase C (PKC) and phosphoinositide-3-kinase (PI3K). Using in vivo and in vitro model systems, we have demonstrated that interleukin-1-generated ether-linked diglycerides (ether-DG) inhibit smooth muscle cell mitogenesis. These novel phospholipid-derived second messengers mimic the effect of interleukin-1 to inhibit cellular proliferation. As ether-DGs are analogues of diacylglycerol (DAG), a co- factor for growth factor-stimulated PKC activation, we hypothesize that ether-DGs can competitively antagonize DAG-activated PKC as a mechanism to diminish smooth muscle mitogenesis. We now demonstrate that DAG analogues enhance PI3K activity. Thus, we also hypothesize that ether-DGs diminish cellular proliferation by competitively antagonizing DAG-stimulated PI3K activity. In Specific Aim 1, the biochemical mechanisms by which ether-DGs inhibit PKC delta and epsilon activation will be investigated in vascular smooth muscle cells. In Specific Aim 2, the role of ether-DGs to inhibit mitogenesis through PKC-dependent or -independent inhibition of P13K will be investigated. These studies will establish ether-DGs as potential therapeutics to limit abnormal vascular smooth muscle cell growth observed in atherosclerotic and restenotic lesions.

DESCRIPTION (provided by applicant): Diabetic retinopathy is characterized by altered vascular permeability and angiogenesis, as well as impaired insulin signaling and resulting apoptosis in retinal neurons. The project is based upon a paradigm shifting postulate suggesting that the underlying abnormality in diabetes is the inappropriate metabolism of palmitate into bioactive ceramide in peripheral non-adipose tissues, including the retina. A corollary to this postulate is that insulin-resistance is a consequence of augmented de novo ceramide synthesis, leading to disruption of insulin-dependent AKT signaling. The overall hypothesis of the present proposal is that altered ceramide metabolism in diabetes leads to insulin receptor dysfunction within membrane microdomains (rafts). Our preliminary data suggest that C16-ceramide selectively accumulates in diabetic retinas, a possible result of palmitic acid-induced de novo synthesis. In addition, exogenous ceramide mimics diabetic-induced insulin resistance, as evidenced by decreased AKT activity and cell viability. We specifically hypothesize that ceramide accumulation within lipid microdomains leads to diminished insulin receptor signaling as a consequence of altered interactions with signaling elements or scaffold proteins. We will use sophisticated biochemicals, molecular and genetic models to demonstrate that altered ceramide metabolism contributes to reduced insulin signaling in the retina. These studies have the potential to identify ceramide accumulation as a target that can be therapeutically or molecularly manipulated.

DESCRIPTION (provided by applicant): Diabetic retinopathy is characterized by altered vascular permeability and angiogenesis, as well as impaired insulin signaling and resulting apoptosis in retinal neurons. The project is based upon a paradigm shifting postulate suggesting that the underlying abnormality in diabetes is the inappropriate metabolism of palmitate into bioactive ceramide in peripheral non-adipose tissues, including the retina. A corollary to this postulate is that insulin-resistance is a consequence of augmented de novo ceramide synthesis, leading to disruption of insulin-dependent AKT signaling. The overall hypothesis of the present proposal is that altered ceramide metabolism in diabetes leads to insulin receptor dysfunction within membrane microdomains (rafts). Our preliminary data suggest that C16-ceramide selectively accumulates in diabetic retinas, a possible result of palmitic acid-induced de novo synthesis. In addition, exogenous ceramide mimics diabetic-induced insulin resistance, as evidenced by decreased AKT activity and cell viability. We specifically hypothesize that ceramide accumulation within lipid microdomains leads to diminished insulin receptor signaling as a consequence of altered interactions with signaling elements or scaffold proteins. We will use sophisticated biochemicals, molecular and genetic models to demonstrate that altered ceramide metabolism contributes to reduced insulin signaling in the retina. These studies have the potential to identify ceramide accumulation as a target that can be therapeutically or molecularly manipulated.

DESCRIPTION (provided by applicant): Ceramide is a lipid-derived second messenger that suppresses vascular smooth muscle (VSM) cell mitogenesis in vitro and in vivo. Multiple laboratories, including our own, have identified protein kinase C zeta (PKCzeta) as a target of ceramide. We have published data demonstrating that ceramide-activated PKCzeta is necessary for VSM cell growth arrest. Two signaling pathways have been identified that contribute to the anti-mitogenic actions of ceramide. Ceramide directly activates PKCzeta, to 1.) induce SAPK signal complex formation;and 2.) inhibit AKT1 signaling cascades. Elucidation of the biophysical and biochemical mechanisms by which ceramide activates PKCzeta is the focus of this new proposal. It is now hypothesized that ceramide stimulates PKCzeta;activity within discrete lipid microdomains or rafts. We will test this hypothesis in the following Specific Aims. In Specific Aim 1, we will identify ceramide-enriched lipid rafts as the site at which PKCzeta, is phosphorylated and optimally activated by upstream kinases. In Specific Aim 2, we will characterize and validate ceramide-binding domains or clefts on PKCzeta. These studies will elucidate the biophysical and biochemical mechanisms by which inflammatory cytokine receptor-induced ceramide formation limits cellular proliferation in models of inflammatory vascular diseases. The long-term innovation of these studies is the clinical potential of direct delivery of ceramide analogues to the site of dysregulated VSM growth observed after angioplasty and stent placement. Additionally, this proposal holds the promise of defining lipidomimetics suitable as therapeutics or screening tools for further drug discovery.

DESCRIPTION (provided by applicant): Diabetic retinopathy is a debilitating complication of diabetes and a leading cause of vision loss;however the fundamental mechanisms contributing to vision loss remain undefined. In our previously funded R03 grant, we hypothesized that altered sphingolipid metabolism contributes to diabetic complications including neuronal apoptosis within the retina. We have now published that dysfunctional glycosphingolipid metabolism may contribute to metabolic stress in diabetes and therapeutic strategies to restore normal sphingolipid metabolism may be a viable approach for treatment of diabetic retinopathy. Specifically, our published and preliminary data demonstrate that glucosylceramide accumulates within diabetic retinas in vivo and that inhibition of glucosylceramide synthase improves insulin sensitivity under hyperglycemic conditions and diminishes inflammatory cytokine-induced retinal neuronal cell death. In the present proposal, we extend these observations to more mechanistic studies. We now hypothesize that hyperglycemia and/or inflammation directly regulate glucosylceramide synthase activity, resulting in accumulation of glucosylceramides. We also hypothesize that pharmacologically targeting glucosylceramide synthase may be therapeutic for diabetic retinopathy. PUBLIC HEALTH RELEVANCE: The underlying cause of diabetic retinopathy is still unknown. We have employed lipidomics, a sophisticated mass spectroscopy strategy, to quantify the mass of lipid metabolites within the diabetic retina. Preliminary and published data have identified dysfunctional glycosphingolipid metabolism in models of Type 1 diabetes. The clinical relevance of our studies is that these lipidomic studies have identified glucosylceramide synthase as a "drugable" target for diabetic complications.

DESCRIPTION (provided by applicant): Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis with the poorest 5-year survival of all gastrointestinal malignancies. Although numerous chemotherapeutic agents have been effective in inhibiting growth of PDAC in vitro or in mice, these agents fail when administered to human subjects in clinical trials. There are two principle reasons for this lack of effectiveness. First, it is difficult to provide an adequate dos of chemotherapeutic agents and avoid systemic toxicity because most agents used for PDAC are not 'tumor- selective', in that they fail to target specific proteins or receptors on the cancer surface. Without tumor specificity, parenteral chemotherapy administration leads to a low concentration of potentially effective agents reaching the cancer and a high incidence of toxicity to other organs. Second, certain promising treatments, such as RNAi, are broken down by nucleases in the blood stream; hence, these compounds have to be given in higher doses or protected from the environment in order to achieve effectiveness in disrupting tumor growth. Regarding targeting, characterization of tumor-specific receptor antigens has significantly improved cancer therapeutics in many malignancies. We have identified a membrane bound growth receptor in human pancreatic cancer cells called the cholecystokinin or CCK- receptor. Using this target, we have developed nontoxic, physiologic calcium phosphosilicate nanoparticles (NPs) with enhanced tumor uptake and delivery compared to untargeted vehicles. Our research team has developed a means to encapsulate either gene therapy or chemotherapeutic agents in NPs, representing a significant improvement over traditional methods. With regard to gene therapy, we have chosen two target genes that have been shown to drive growth of PDAC: gastrin and mutated Kras. We hypothesize that treatment of PDAC may be significantly improved through the application of nanotechnology using tumor-selective delivery vehicles in which drugs or gene therapy are protected through encapsulation. In order to test this hypothesis we plan to carry out the following Specific aims: 1) Optimize a new generation of PDAC-specific nanoparticles and verify improved encapsulation of therapeutic agents using single molecule spectroscopy and 2) Determine pharmacokinetic parameters for targeted NPs including the maximum tolerated dose, biodistribution and bioavailability, and 3) Examine the safety and efficiency of target-specific loaded nanoparticles to inhibit growth of pancreatic cancer cells in vitro and in vivo. Our long term goal is to develop novel effective strategies to improve therapy and survival of patients with this devastating malignancy.

The Biostatistics Core serves as the focal point of biostatistics support for all the four Projects. The Core will provide regular advice on experimental design such as selection of end points, sample size and power, and optimal allocation of animal and dose. The Core handles data management of the four Projects in a secure central location and in a format consistent across Projects. The Core will perform expert statistical analyses that optimally answer the research question and represent state of the art practice. The Core will also facilitate data sharing with the general scientific community. The Core is staffed by two experienced biostatisticians who have daily working relationships with the Project investigators. Their offices are on the third floor of the Cancer Institute building, in close proximity to most of the Program Project investigators. The Core biostatisticians have been an integral part of the P01 application through working on experimental design, analyzing preliminary data and developing a detailed and tailored statistical plan for each Project. The Core biostatisticians have made a concerted effort to learn the clinical and biological science in this AML Program Project so as to provide the strongest statistical service. The Core has access to all needed software such as Microsoft Office 2007, SAS 9.3 and R. A dedicated Biostatistics Core provides easy and guaranteed access for the Program Project investigators and also allows biostatisticians to specialize in the Project areas, in terms of the scientific knowledge and in biostatistics expertise A dedicated Core provides timely and high quality biostatistics service as its focus. Cost-effectiveness is enhanced because the cumulative experience of all Core personnel and the combined facilities and resources are available to each of the four Projects. The Biostatistics Core also serves as an interface to the larger resources in biostatistics, data management and computing in the Department of Public Health Sciences. No additional computer hardware and software are needed.

Human acute myelogenous leukemia (AML) is highly heterogeneous and, as demonstrated by this group, exhibits significant variability in sphingoiipid metabolism. Current therapy of AML is highly toxic, yielding ultimately inadequate outcomes for the vast majority of patients. Cell lines are limited in their representation of primary AML subtypes and manifest clonal evolution in culture, suggesting limitations in their relationship to the primary case material. The systematic study of these diseases thus requires access to primary samples representing a substantial pool of cases, and correlation of these samples to clinical data including treatment outcomes. Animal models of various kinds are available, but models representing direct leukemogenesis via expression of relevant oncogenic proteins and immunodeficient xenografts propagating primary AML, provide relevant platforms for studying developing therapies. In this Core, materials and models will be provided to each Project to allow completion of proposed objectives. The following specific aims will be pursued: Specific Aim 1: Expand and maintain the PSHCI leukemia cell bank to provide programmatic access to cell and plasma samples from a broad variety of AML patients and normal hematopoietic controls. Samples will be cryopreserved in multiple aliquots to allow repeated interrogation via developing technologies. Clinical data will be collected and available to provide biologically meaningful categorization of AMLs. Specific Aim 2: Develop and maintain a menu of animal models in which to test promising program-derived therapies. Two such models are available. Subaim 2A: Xenograft models of primary human leukemia have been developed in N0D/SCID/IL2ry (NSG) murine hosts and used as platforms for testing novel therapies. Multiple lines (originating from multiple AMLs of differing subtypes) will be passaged in NSG animals to provide in vivo validation of therapeutics. Human cord blood will be expanded in NSG mice to provide normal controls for in vivo toxicity studies. Subaim 2B: Murine syngeneic models of AML using retroviral transduction of murine bone marrow cells with fusion protein oncogenes. We have established a MLL-AF9 retroviral transduction model, which develops a stem cell derived leukemia shown to be inhibited by Project-derived therapeutics. This Core is essential to the overall Program, each project of which uses primary, cells and in vivo models as provided here. These materials and testing platforms will allow development of novel therapies for these lethal diseases.

The Synthesis and Nanoformulation Core (SNC) will supply ceramide analogs, acid ceramidase (AC) inhibitors, sphingosine kinase inhibitors, and tamoxifen metabolites essential to the members of this Program Project. In addition, the Core will also provide liposomal formulations of C6-ceramide derivatives, acid ceramidase inhibitors, sphingosine kinase inhibitor SKI-178, and tamoxifen metabolites to the Projects 1, 2, 3, and 4, respectively. Furthermore, the Core will also synthesize [^H] AC inhibitors and [^

An important objective of the POl application is to define the contribution of altered sphingolipid metabolism in Acute Myeloid Leukemia (AML). Through the multiple Projects, the roles of specific sphingolipids and sphingolipid enzymes in AML and the efficacy of therapeutically targeting sphingolipid metabolism for AML will be defined. In order to achieve these objectives the Targeted Sphingomics Core will provide critical information to the Projects through two objectives; 1) The Core will quantify changes in the sphingolipidome (lipids and proteins), identifying new therapeutic targets for AML, and testing the efficacy of sphingolipid-based therapeutics and 2) the Core will provide standardized measurements of sphingolipids and their metabolizing enzymes for all four Projects. These objectives will create new hypotheses into the roles of sphingolipids in AML and serves to assist the Projects in testing their specific hypotheses. Taken together, this will lead to an understanding of the contributions of, and therapeutic efficacy of, targeting sphingolipid metabolism.

The Program's broad long-term objective is to develop new targeted therapeutics for acute myelogenous leukemia (AML). The overarching hypothesis of the Program Project is that sphingolipid metabolism is altered in AML and can be used to direct therapeutic regimens. A corollary of this hypothesis suggests that novel therapeutics that target dysfunctional sphingolipid metabolism may be highly efficacious in AML. The integration of the Program follows the metabolism of ceramide. Project 1 targets ceramide metabolism utilizing ceramide-based nanotherapeutics; Projects 2 and 3 target acid ceramidase and sphingosine kinase, which coordinately generate the pro-mitogenic and anti-apoptotic ceramide metabolite, sphingosine- 1-phosphate, and Project 4 targets P-glycoprotein-mediated glycosylation of ceramide. All Projects have validated therapeutic modalities in both in vitro and in vivo models of AML. The Program is supported by five integral Cores. These include the: Synthesis and Nanoformulation Core, which provides synthesized compounds not available commercially for biologic studies; Targeted Sphingomics Core, which is essential for quantification of sphingolipid metabolism; Animal Modeling and Clinical Resources Core, which provides state-of-the-art molecularly defined AML samples with annotated clinical outcomes and murine leukemia stem cells models; Biostatistics Core, which provides critical research design and analysis; Administrative Core, which provides oversight and coordination of all scientific, administrative, and fiscal activities. Development of targeted therapeutics for AML will be pursued in the following overall Specific Aims of the Program: 1. Engineer, characterize and optimize novel lipomimetic- or small molecule-based therapeutics for AML. 2. Validate the efficacy and toxicology of sphingolipid-targeted therapeutics in vivo using murine leukemia stem cells models. 3. Define the role of altered sphingolipid metabolism in cell survival, apoptosis, autophagy, and drug resistance in AML. To accomplish these Aims, we have assembled a transdisciplinary team of clinical and basic scientists, organic chemists, and material scientists. We are fortunate that NCI NanoCharacterization Laboratory has accelerated pre-clinical development of the Penn State ceramide liposomal nanoplatform. The clinical significance of the Program rests on the urgent and unmet needs for development of new therapeutics in AML. In the revised application, we have specifically responded to all of the reviewer's critiques, in particular, addressing the major issues associated with AML heterogeneity and humanized AML murine models. Importantly, we have documented engraftment in NSG mice of AML subsets defined by integrated genetic profiling.

The broad long-term objective of this proposal is to develop better therapeutics for acute myeloid leukemia (AML). There is an urgent unmet need for development of new therapy for AML as only 25% of patients achieving complete remission remain disease free. There is increasing evidence that an imbalance in the sjDhingolipid biostat contributes to pathogenesis and drug resistance in AML. Preliminary data demonstrate altered sphingolipid metabolism in this disease, including increased levels of pro-survival sphingosine-1-phosphate and constitutive overexpression of key enzymes, acid ceramidase (AC) and sphingosine kinase 1 (Project 3). Our central hypothesis is that AC inhibition leads to therapeutic efficacy by both increasing production of pro-apoptotic ceramide species and by blocking conversion of ceramide to pro- survival glycosylated metabolites. We will test the hypothesis that AC mediates survival of AML blasts/leukemia stem cells (LSC) in Specific Aim 1. Preliminary data indicate that AC is a valid therapeutic target in AML. AC activity is overexpressed in patient AML cells and in LSC; AC inhibition with LCL-204 leads to apoptosis of AML cells. We show that AC inhibition causes accumulation of pro-apoptotic ceramide, predominantly Cis species. Compelling preliminary data support a model in which S1P/AC/Mcl-1 axis regulates leukemia cell survival. We will also test the hypothesis that AC confers a drug resistance phenotype in AML (Specific Aim 2). We have found that AC expression/NF-KB activation modulates expression of P-glycoprotein (P-gp) and that AC inhibition sensitizes drug resistant AML cells to standard AML therapeutics. We suggest that P-gp-mediated drug resistance does not involve conventional efflux of therapeutics. Rather, based on Project 4 findings, we hypothesize that downregulation of P-gp blocks ceramide flux leading to decrease in levels of pro-survival ceramide metabolites. Our overall strategy will utilize a genetic approach to inhibit AC in both specific aims. We will also test therapeutic AC inhibitors LCL-204 and its analogs in murine LSC models. We expect that the proposed research will have significant impact on the field of AML biology. We anticipate that our in vivo work with AC inhibitors will validate a novel sphingolipid therapeutic approach for treatment of AML.

The sphingolipid ceramide is a potent tumor suppressor that contributes to the promotion of apoptosis and autophagy. Management of these responses in cancer cells is dependent on the dynamic balance between ceramide which is pro-apoptotic and its metabolites, which can promote cell survival. Upregulated glycosylation of ceramide, a major pathway contributing to ceramide detoxification, limits the valuable tumor suppressor effects of ceramide. This proposal will focus on reducing ceramide glycosylation with the goal of devising novel ceramide therapies for treatment of acute myeloid leukemia (AML), the most common type of leukemia in adults. Upregulated ceramide catabolism is associated with multidrug resistance in leukemia. In our study we will use ceramide exogenously in the form of short-chain, cell-permeable C6-ceramide (C6-cer) nanoliposomes, a system that offers advantages over other delivery systems or the use of natural ceramide, which due to solubility and transport limitations, cannot be administered exogenously. Our objective is to develop innovative approaches for treating AML, and this will be achieved by delivering C6-cer in conjunction with adjuvants that will attenuate metabolism and thereby amplify ceramide-driven cell death. To attenuate C6-cer metabolism, we will employ P-glycoprotein (P-gp) antagonists as adjuvants. We hypothesize that intracellular P-gp, because of its role in glycolipid trafficking, will be a highly effective target for attenuating C6-cer metabolism.. We also hypothesize that P-gp antagonists will increase the intracellular levels of both C6-cer and long-chain ceramides and magnify end-point responses (apoptosis, autophagy, cell cycle arrest). Because of the major role that P-gp plays in regulating the metabolism of short-chain ceramides, this project hallmarks a shift in clinical strategy by introducing the use of P-gp antagonists as modulators of ceramide metabolism and enhancers of ceramide cytotoxicity, an activity divorced from the much investigated chemotherapy effluxing/multidrug resistance protein we all know. To make nanoliposomal C6-cer more effective as a therapeutic in AML, the following aims will be pursued: 1) Determine the influence of P-gp expression on C6-cer cytotoxicity and metabolism in AML cell models. Understanding the relationship of P- gp and cellular response to C6-cer is critical for optimizing ceramide-based therapeutics. 2) Determine the effect of inhibiting C6-cer catabolism on cytotoxic response to C6-cer in defined AML cell lines and patient cells. We hypothesize that blocking C6-cer catabolism, including conversion to sphingomyelin, will synergistically amplify cytotoxicity. 3) Elucidate the mechanism of cell death and the signaling events associated with cytotoxicity of combination C6-cer/P-gp antagonists in AML cells. 4) Determine the effect of adjuvant inhibitors on response to C6-cer therapy in in vivo AML mouse models. Dysfunctional ceramide metabolism promotes resistance to apoptosis. We expect to discover that partnering nanoliposomal C6-cer with P-gp antagonists (that block ceramide catabolism) will be a novel, innovative, non-toxic treatment for AML. RELEVANCE (See instructions): Acute myelogenous leukemia (AML), the most common type of leukemia in adults, is an aggressive cancer, and only about 25% of patients who experience remission with chemotherapy remain disease-free. There is thus a pressing need in public health to develop effective therapies that can extend remission and in the best case scenario, offer cure. This project will address this issue by evaluating novel combinations of agents designed to reinforce and potentiate biochemical signals that kill leukemia cells without harm to normal cells.

AML is a heterogeneous group of malignant disorders whose primary therapy has changed little in recent decades. Sphingolipid metabolism, centered on the pro-apoptotic molecule ceramide, represents an understudied therapeutic avenue in this and other malignancies. This project stems from the hypothesis that ceramide-based therapeutics can be utilized as selective and sensitive anti-cancer agents. Unfortunately, the potential of ceramide-based therapeutics is severely limited by cell-impermeability and hydrophobicity. We have pioneered the use of nanotechnology to turn ceramide from a hydrophobic agent into a hydrophilic drug, engineering a C6-ceramide nanoliposome with clear efficacy in cancer models. Preliminary data suggest that ceramide nanoliposomes are active in multiple AML cell lines and primary cases, but sensitivity is highly variable. Thus, the goal of the project is the design of second-generation ceramide nanoliposomes that exert efficacy in AML patients who are resistant to conventional chemotherapy. In Specific Aim 1, we will optimize second-generation nanoliposomal ceramide therapy for the treatment of AML. To maximize efficacy, ceramide nanoliposomes will be re-engineered via encapsulation of pharmacological agents to inhibit ceramide metabolism or autophagy. We will also actively target ceramide nanoliposomes to AML progenitor populations, initially via conjugation of anti-CD117 (c-kit), which is preferentially expressed in hematopoitic stem cells. In Specific Aim 2, we will investigate mechanisms underlying the enhanced efficacy between ceramide nanoliposomes and pharmacological agents that inhibit ceramide metabolism or autophagy. Specifically, based upon preliminary data, we will investigate if this synergism is mediated via a molecular-based switch from autophagy to apoptosis and/or a synergistic elevation of long chain pro-apoptotic ceramide species. We will also characterize the contribution of selective ceramide synthases to the elevation of long chain ceramide species in defined AML patient subtypes. With the indispensable support of programmatic projects and cores, this project will rapidly characterize and validate the efficacy of second-generation ceramide nanoliposomes in defined AML populations.

Little improvement in clinical outcomes has been achieved in acute myeloid leukemia (AML) patients over the past several decades. With this need in mind, we have initiated this project with the overall goal of validating Sphingosine Kinase 1 (SphKI) as a novel molecular target and further developing our novel SphKI-selective inhibitor (SKI-178) as an effective therapeutic agent for AML. SphKI, which can function as a pro-tumorigenic factor, is a signaling lipid kinase that catalyzes the formation of pro-mitogenic sphingosine-1-phosphate (S1P) at the expense of pro-apoptotic ceramide. Accumulating evidence indicates that SphKI is a protein commonly over-expressed in AML cells. Studies showed that upregulation of this lipid kinase alters the balance of sphingoiipid signaling in AML cells in ways that promote AML cell growth/proliferation, while simultaneously blocking apoptotic cell death. On the other hand, evidence shows that inhibition of SphKI expression/activity in AML cells blocks pro-mitogenic/prosurvival SIP signaling and concomitantly induces anti-mitogenic/pro-apoptotic ceramide signaling, resulting in apoptotic cell death. These findings support that targeting SphKI is an exciting new therapeutic approach in AML. As such, we have identified and optimized a SphKI-selective small molecule inhibitor (SKI-178). The preliminary evidence indicates that inhibition of SphKI activity by SKI- 178 results in AML cell apoptosis in a ceramide-dependent manner. Based on these findings and other evidence, it is hypothesized that SKI-178 induces AML cell apoptosis by activating a Cer-dependent JNK/Bcl-2/Caspase-3/7 signaling pathway. The specific goals of the proposed study are to: A) elucidate the mechanism-of-action (MOA) by which SKI-178 induces AML cell apoptosis by modulating sphingoiipid metabolite formation, thus validating SphKI as a novel molecular target in AML and B) establish the efficacy and safety profile of SKI-178 using both primary human AML (hAML) cells and in vivo mouse AML model systems. To accomplish these goals, we have developed a team of investigators composed of basic scientists with expertise in SphKI signaling and cancer biology, synthetic chemists with expertise in medicinal chemistry and clinical scientists with expertise in AML. The results obtained from the in vitro and in vivo assessment of our novel SphKI-selective inhibitor, SKI-178, will provide insights into the improvement of pharmacological therapeutic agents that selectively target SphKI in AML.

The overarching goal of the Administrative Core is to oversee and coordinate all scientific, regulatory, administrative and fiscal responsibilities of the Program Project grant. The Administrative Core will accomplish its goal through the following specific aims: 1. Ensure integration of all Projects and Cores by managing all oversight strategies, including coordinating the meetings and the External and Internal Advisory Committees and implementing the recommendations of these Committees. 2. Authority to realign resources based upon advice from the External and Internal Advisory Committees in collaboration with the Executive Committee (Program Leaders and Project/Core Leaders). 3. Administer and implement the multiple Principal Investigator Plan. 4. Organize the monthly meetings of the Executive Committee, biannual meeting of Internal Advisory Committee and fri-annual meeting of External Advisory Committee. Organize the POl yearly retreat to assess overall P01 progress, based upon quantitative milestones, and plan and implement next steps making use of the reports from the Internal and External Advisory Committees. 5. Provide fiscal accountability via coordination with Institutional and NCI staff. 6. Document productivity of all Projects and Cores, as defined by discrete endpoints such as manuscripts, filed provisional patent applications, and invited lectures. 7. Prepare all progress reports and responses to External and Internal Advisory Committees. 8. Coordinate and oversee all scientific, regulatory, administrative and fiscal interactions between The John Wayne Cancer Institute, Memorial Sloan-Kettering Cancer Center, Mt Sinai Medical Center, The Jackson Laboratory and Penn State University. 9. Provide oversight management to ensure that biostatistics analyses and plans are implemented for all Projects and Cores. 10. Coordinate Data Sharing modalities between Institutions, NIH, NCL and the public. 11. Coordinate the monthly Core presentations to the Executive Committee that will include description of the active and pending requests for support from each Project.

ABSTRACT Great progress has been made in manipulating the immune system to eliminate established tumors including hepatocellular cancer (HCC). However, the lack of a clinically-relevant animal model largely impedes our understanding of HCC-induced immune evasion. Therefore, prevention of tumor-induced immunotolerance to develop effective immunotherapies against HCC is still a challenging task. We recently created a novel murine model with immunocompetent mice. This model reflects most typical features of human HCC including immune escape. Tumor growth in this model induces profound immune tolerance characterized by increase in the frequency of tumor-associated macrophages (TAMs), regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), liver sinusoidal endothelial cells (LSECs) as well as profound exhaustion of effector CD8+T cells. We have thus established a unique platform to investigate the mechanism of tumor-induced immune tolerance and to develop proof-of-concept therapeutic strategies for HCC toward eventual clinical translation. Ceramide has tumoricidal activity. We use advanced nanotechnology to make nanoliposome-loaded C6- ceremide (LipC6). The formulated LipC6 overcomes ceramide cell impermeability and aqueous precipitation, while enhancing cellular retention, promoting its clinical use as a drug. The combination of LipC6 with adoptive transfer of tumor antigen-specific CD8+ T-cell plus immunization with tumor-specific antigens not only retarded tumor growth but also regressed established tumors, suggesting that the combination of LipC6 with immunotherapies has a synergistic therapeutic effect in HCC control. The overall objective of this proposal is to dissect the underlying mechanisms by which LipC6 breaks tumor-induced immune tolerance to rescue antitumor immune activity and develop a clinically useful LipC6-integrated immunotherapy for HCC. Further studies reveal that LipC6 treatment modulates TAM and LSEC in cellular level; and regulates reactive oxygen species (ROS), interferon regulator factor (IRF), and fatty acyl-COA reductase 2(Far2), PD1 in molecular level in HCC. Anti-PD1 antibodies treatment effectively impedes HCC growth. Thus, we hypothesize that LipC6 targets TAM and LSEC to resurrect anti-tumor immune reactivity by regulating ROS, IRF, and Far2 pathways; thus LipC6 in combination with anti-PD1 antibodies to block PD1/PD-L1 pathway not only strongly activate anti-HCC immunity but also result in unprecedented therapeutic efficacy. We will test our hypothesis through aims 1: Dissect the cellular mechanisms by which LipC6 modulates TAM and LSEC to impact anti-tumor immunity in tumor-bearing mice. 2. Dissect the molecular mechanisms by which LipC6 modulates macrophages through ROS and IRF pathways, and LSEC through Far2 pathway in the setting of HCC. 3. Define the therapeutic efficacy of LipC6 in combination with anti-PD-1 Abs for HCC treatment and elucidate the underlying mechanisms. This study will provide better insights into the mechanisms of an effective LipC6-immunotherapeutic intervention in HCC control. The findings will lead to new treatments and therapeutic targets, and better anticancer strategies.

Triple negative breast cancer poses a persistent clinical challenge given that it is refractory to most available endocrine or targeted therapies. Indeed, patient prognosis is dim in light of shorter median time to relapse and death compared to other breast cancer subtypes. Broadly speaking, our group is working to develop an improved therapy regimen for this patient population. We propose to achieve this by combining 2 separate treatment modalities [i.e. ceramide nanoliposomses (CNL) and image-guided focused ultrasound (FUS) ablation/heating] that we postulate will offer therapeutic synergy. Our expectation of synergy between CNL and FUS is based on evidence that (i) they are both capable of reducing, perhaps through distinct mechanisms, immunosuppression in the tumor microenvironment and (ii) the delivery of systemically administered liposomes is markedly enhanced in FUS-targeted tumors. The proposal consists of 2 specific aims. Aim 1 will be to determine which FUS regime (sub-ablative heating or partial thermal ablation) most effectively enhances the treatment efficacy of ceramide nanoliposomes against breast cancer. FUS will be applied to 4T1 (triple negative) breast tumors in combination with CNL administration. Determination of the most efficacious FUS regime will be made based upon tumor growth and animal survival data. Mass spectrometry of excised tumors will ascertain whether FUS enhances ceramide delivery. We will also perform comprehensive immunological analyses on tumor tissue, tumor draining lymph nodes (LNs), non-draining LN, spleen, and blood. Aim 2 will then be to investigate whether the most therapeutically efficacious combination of FUS and CNL is associated with toxicity. We will repeat the most efficacious FUS+CNL combination from Aim 1 and assess toxicity (liver and cardiac enzymes, cardio/neural and pulmonary physiological parameters, and hematological and immunological markers). Finally, we will perform ex-vivo studies to examine whether FUS application affects CNL chemistry. Going forward, note that Co-PI Kester has already successfully received an IND from the FDA (IND 109487) to initiate a phase 1 trial. If the proposed studies are successful, a follow-on phase 1/2 trial with CNL and FUS would ensue at our institution.

PROJECT SUMMARY Acute Myeloid Leukemia (AML) is the 2nd most common type of leukemia diagnosed with a 5-year survival rate of only 27%. Though dose-intensive induction and consolidation chemotherapy induces clinical complete remission in the majority of patients suitable for treatment, most relapse whereas others develop refractory AML. Recently, the Bcl-2 inhibitor, venetoclax, demonstrated improved clinical outcomes when combined with the conventional therapeutic, cytarabine (AraC), in relapsed and refractory AML. Based upon efficacy in preclinical models, we hypothesize that liposomal delivery of the pro-apoptotic bioactive lipid C6-ceramide will augment the efficacy of this low dose AraC/venetoclax standard-of-care regimen and have a meaningful clinical impact in treating relapsed/refractory AML. This hypothesis will be examined in three Specific Aims. In Specific Aim 1, a Phase 1b (dose escalation)/2a (dose-expansion) clinical trial for ceramide nanoLiposomes (CNL) in relapsed/refractory AML patients treated in combination with low dose AraC and venetoclax (pre-IND #142902, UVA Protocol Review Committee Approval #5414, CAV trial) will be conducted. The premise of this trial is supported by the fact that CNL has already reached its putative MTD in an FDA (IND 109471, NCT02834611) NCI-supported (U43 CA186118) Phase 1 trial for solid tumors, where CNL has been well- tolerated with multiple patients exhibiting stable disease. In Specific Aim 2, we examine the underlying cooperativity between CNL, AraC, and venetoclax in AML. We show that co-administration of CNL with AraC and/or venetoclax exerts multiple synergistic mechanisms of efficacy. First, we demonstrate that this regimen increases the ratio of pro-apoptotic C16- and C18-ceramides over less apoptotic C24 ceramides. Utilizing molecular strategies in both in vitro and in vivo models, we will test the hypothesis that this is mediated by ceramide synthases and determine how ceramide synthases regulate AML survival. Second, we show that CNL reduces venetoclax-induced elevation of pro-survival proteins. We will test the hypothesis that this effect is STAT3-dependent using molecular approaches in preclinical models. In Specific Aim 3, we show that the ratio of C18 to C24 ceramides predicts progression-free survival in AML patients, which is the first application of this ratio as a biomarker for cancer. We will extend and confirm sphingolipid metabolites or ratios as biomarkers of AML biology and prognosis utilizing large, well-characterized AML samples as a validation cohort. while also investigating clinical samples from Specific Aim 1 to assess biomarkers of CNL efficacy. Published and unpublished observations demonstrate that high-expression of enzymes that decrease ceramide levels (acid ceramidase, sphingosine kinase, glucosylceramide synthase) and reduce pro-apoptotic ceramides (e.g. C16/C18) leads to lower survival in AML patients. Together, the proposed studies will test the clinical application and unravel the mechanistic pathways of CNL cooperativity with AraC/venetoclax, while ascertaining the prognostic impact of dysregulated sphingolipid metabolism in AML.