MDA-9/Syntenin in the tumor and microenvironment defines prostate cancer bone metastasis.

Bone metastasis is a frequent and incurable consequence of advanced prostate cancer (PC). An interplay between disseminated tumor cells and heterogeneous bone resident cells in the metastatic niche initiates this process. Melanoma differentiation associated gene-9 (mda-9/Syntenin/syndecan binding protein) is a prometastatic gene expressed in multiple organs, including bone marrow-derived mesenchymal stromal cells (BM-MSCs), under both physiological and pathological conditions. We demonstrate that PDGF-AA secreted by tumor cells induces CXCL5 expression in BM-MSCs by suppressing MDA-9-dependent YAP/MST signaling. CXCL5-derived tumor cell proliferation and immune suppression are consequences of the MDA-9/CXCL5 signaling axis, promoting PC disease progression. mda-9 knockout tumor cells express less PDGF-AA and do not develop bone metastases. Our data document a previously undefined role of MDA-9/Syntenin in the tumor and microenvironment in regulating PC bone metastasis. This study provides a framework for translational strategies to ameliorate health complications and morbidity associated with advanced PC.

Dual Targeting of the PDZ1 and PDZ2 Domains of MDA-9/Syntenin Inhibits Melanoma Metastasis.

Genome-wide gene expression analysis and animal modeling indicate that melanoma differentiation associated gene-9 (mda-9, Syntenin, Syndecan binding protein, referred to as MDA-9/Syntenin) positively regulates melanoma metastasis. The MDA-9/Syntenin protein contains two tandem PDZ domains serving as a nexus for interactions with multiple proteins that initiate transcription of metastasis-associated genes. Although targeting either PDZ domain abrogates signaling and prometastatic phenotypes, the integrity of both domains is critical for full biological function. Fragment-based drug discovery and NMR identified PDZ1i, an inhibitor of the PDZ1 domain that effectively blocks cancer invasion in vitro and in vivo in multiple experimental animal models. To maximize disruption of MDA-9/Syntenin signaling, an inhibitor has now been developed that simultaneously binds and blocks activity of both PDZ domains. PDZ1i was joined to the second PDZ binding peptide (TNYYFV) with a PEG linker, resulting in PDZ1i/2i (IVMT-Rx-3) that engages both PDZ domains of MDA-9/Syntenin. IVMT-Rx-3 blocks MDA-9/Syntenin interaction with Src, reduces NF-κB activation, and inhibits MMP-2/MMP-9 expression, culminating in repression of melanoma metastasis. The in vivo antimetastatic properties of IVMT-Rx-3 are enhanced when combined with an immune-checkpoint inhibitor. Collectively, our results support the feasibility of engineering MDA-9 dual-PDZ inhibitors with enhanced antimetastatic activities and applications of IVMT-Rx-3 for developing novel therapeutic strategies effectively targeting melanoma and in principle, a broad spectrum of human cancers that also overexpress MDA-9/Syntenin.

CPT1A-mediated fatty acid oxidation confers cancer cell resistance to immune-mediated cytolytic killing.

Although tumor-intrinsic fatty acid ß-oxidation (FAO) is implicated in multiple aspects of tumorigenesis and progression, the impact of this metabolic pathway on cancer cell susceptibility to immunotherapy remains unknown. Here, we report that cytotoxicity of killer T cells induces activation of FAO and upregulation of carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme of FAO in cancer cells. The repression of CPT1A activity or expression renders cancer cells more susceptible to destruction by cytotoxic T lymphocytes. Our mechanistic studies reveal that FAO deficiency abrogates the prosurvival signaling in cancer cells under immune cytolytic stress. Furthermore, we identify T cell-derived IFN-γ as a major factor responsible for induction of CPT1A and FAO in an AMPK-dependent manner, indicating a dynamic interplay between immune effector cells and tumor targets. While cancer growth in the absence of CPT1A remains largely unaffected, established tumors upon FAO inhibition become significantly more responsive to cellular immunotherapies including chimeric antigen receptor-engineered human T cells. Together, these findings uncover a mode of cancer resistance and immune editing that can facilitate immune escape and limit the benefits of immunotherapies.

Ubiquitin-like protein 5 is a novel player in the UPR-PERK arm and ER stress-induced cell death.

Biological functions of the highly conserved ubiquitin-like protein 5 (UBL5) are not well understood. In Caenorhabditis elegans, UBL5 is induced under mitochondrial stress to mount the mitochondrial unfolded protein response (UPR). However, the role of UBL5 in the more prevalent endoplasmic reticulum (ER) stress-UPR in the mammalian system is unknown. In the present work, we demonstrated that UBL5 was an ER stress-responsive protein, undergoing rapid depletion in mammalian cells and livers of mice. The ER stress-induced UBL5 depletion was mediated by proteasome-dependent yet ubiquitin-independent proteolysis. Activation of the protein kinase R-like ER kinase arm of the UPR was essential and sufficient for inducing UBL5 degradation. RNA-Seq analysis of UBL5-regulated transcriptome revealed that multiple death pathways were activated in UBL5-silenced cells. In agreement with this, UBL5 knockdown induced severe apoptosis in culture and suppressed tumorigenicity of cancer cells in vivo. Furthermore, overexpression of UBL5 protected specifically against ER stress-induced apoptosis. These results identify UBL5 as a physiologically relevant survival regulator that is proteolytically depleted by the UPR-protein kinase R-like ER kinase pathway, linking ER stress to cell death.

The Pleiotropic Ubiquitin-Specific Peptidase 16 and Its Many Substrates.

Ubiquitin-specific peptidase 16 (USP16) is a deubiquitinase that plays a role in the regulation of gene expression, cell cycle progression, and various other functions. It was originally identified as the major deubiquitinase for histone H2A and has since been found to deubiquitinate a range of other substrates, including proteins from both the cytoplasm and nucleus. USP16 is phosphorylated when cells enter mitosis and dephosphorylated during the metaphase/anaphase transition. While much of USP16 is localized in the cytoplasm, separating the enzyme from its substrates is considered an important regulatory mechanism. Some of the functions that USP16 has been linked to include DNA damage repair, immune disease, tumorigenesis, protein synthesis, coronary artery health, and male infertility. The strong connection to immune response and the fact that multiple oncogene products are substrates of USP16 suggests that USP16 may be a potential therapeutic target for the treatment of certain human diseases.

SRA inhibition improves antitumor potency of antigen-targeted chaperone vaccine.

We have previously demonstrated that scavenger receptor A (SRA) acts as an immunosuppressive regulator of dendritic cell (DC) function in activating antitumor T cells. Here we investigate the potential of inhibiting SRA activity to enhance DC-targeted chaperone vaccines including one that was recently evaluated in melanoma patients. We show that short hairpin RNA-mediated SRA silencing significantly enhances the immunogenicity of DCs that have captured chaperone vaccines designed to target melanoma (i.e., hsp110-gp100) and breast cancer (i.e., hsp110-HER/Neu-ICD). SRA downregulation results in heightened activation of antigen-specific T cells and increased CD8+ T cell-dependent tumor inhibition. Additionally, small interfering RNA (siRNA) complexed with the biodegradable, biocompatible chitosan as a carrier can efficiently reduce SRA expression on CD11c+ DCs in vitro and in vivo. Our proof-of-concept study shows that direct administration of the chitosan-siRNA complex to mice promotes chaperone vaccine-elicited cytotoxic T lymphocyte (CTL) response, culminating in improved eradication of experimental melanoma metastases. Targeting SRA with this chitosan-siRNA regimen combined with the chaperone vaccine also leads to reprogramming of the tumor environment, indicated by elevation of the cytokine genes (i.e., ifng, il12) known to skew Th1-like cellular immunity and increased tumor infiltration by IFN-γ+CD8+ CTLs as well as IL-12+CD11c+ DCs. Given the promising antitumor activity and safety profile of chaperone vaccine in cancer patients, further optimization of the chitosan-siRNA formulation to potentially broaden the immunotherapeutic benefits of chaperone vaccine is warranted.

Sphingosine Kinase 2 in Stromal Fibroblasts Creates a Hospitable Tumor Microenvironment in Breast Cancer.

Reciprocal interactions between breast cancer cells and the tumor microenvironment (TME) are important for cancer progression and metastasis. We report here that the deletion or inhibition of sphingosine kinase 2 (SphK2), which produces sphingosine-1-phosphate (S1P), markedly suppresses syngeneic breast tumor growth and lung metastasis in mice by creating a hostile microenvironment for tumor growth and invasion. SphK2 deficiency decreased S1P and concomitantly increased ceramides, including C16-ceramide, in stromal fibroblasts. Ceramide accumulation suppressed activation of cancer-associated fibroblasts (CAF) by upregulating stromal p53, which restrained production of tumor-promoting factors to reprogram the TME and to restrict breast cancer establishment. Ablation of p53 in SphK2-deficient fibroblasts reversed these effects, enabled CAF activation and promoted tumor growth and invasion. These data uncovered a novel role of SphK2 in regulating non-cell-autonomous functions of p53 in stromal fibroblasts and their transition to tumor-promoting CAFs, paving the way for the development of a strategy to target the TME and to enhance therapeutic efficacy. SIGNIFICANCE: Sphingosine kinase 2 (SphK2) facilitates the activation of stromal fibroblasts to tumor-promoting cancer-associated fibroblasts by suppressing host p53 activity, revealing SphK2 as a potential target to reprogram the TME.

Restoration of CD4+ T Cells during NAFLD without Modulation of the Hepatic Immunological Pattern Is Not Sufficient to Prevent HCC.

Predominant inflammatory immunological patterns as well as the depletion of CD4+ T cells during nonalcoholic fatty liver disease (NAFLD) are reported to be associated with the progression of hepatocellular carcinoma (HCC). Here, we report that an LRP-1 agonistic peptide, SP16, when administered during advanced NAFLD progression, restored the depleted CD4+ T cell population but did not significantly affect the inflammatory immunological pattern. This data suggests that restoration of CD4+ T cells without modulation of the hepatic immunological pattern is not sufficient to prevent HCC. However, SP16 administered early during NAFLD progression modulated the inflammatory profile. Future studies will determine if regulation of the inflammatory immune response by SP16 early in NAFLD progression will prevent HCC.

Radiation induces ESCRT pathway dependent CD44v3+ extracellular vesicle production stimulating pro-tumor fibroblast activity in breast cancer.

Despite recent advances in radiotherapeutic strategies, acquired resistance remains a major obstacle, leading to tumor recurrence for many patients. Once thought to be a strictly cancer cell intrinsic property, it is becoming increasingly clear that treatment-resistance is driven in part by complex interactions between cancer cells and non-transformed cells of the tumor microenvironment. Herein, we report that radiotherapy induces the production of extracellular vesicles by breast cancer cells capable of stimulating tumor-supporting fibroblast activity, facilitating tumor survival and promoting cancer stem-like cell expansion. This pro-tumor activity was associated with fibroblast production of the paracrine signaling factor IL-6 and was dependent on the expression of the heparan sulfate proteoglycan CD44v3 on the vesicle surface. Enzymatic removal or pharmaceutical inhibition of its heparan sulfate side chains disrupted this tumor-fibroblast crosstalk. Additionally, we show that the radiation-induced production of CD44v3+ vesicles is effectively silenced by blocking the ESCRT pathway using a soluble pharmacological inhibitor of MDA-9/Syntenin/SDCBP PDZ1 domain activity, PDZ1i. This population of vesicles was also detected in the sera of human patients undergoing radiotherapy, therefore representing a potential biomarker for radiation therapy and providing an opportunity for clinical intervention to improve treatment outcomes.

Enhanced Cancer Therapy Using an Engineered Designer Cytokine Alone and in Combination With an Immune Checkpoint Inhibitor.

melanoma differentiation associated gene-7 or Interleukin-24 (mda-7, IL-24) displays expansive anti-tumor activity without harming corresponding normal cells/tissues. This anticancer activity has been documented in vitro and in vivo in multiple preclinical animal models, as well as in patients with advanced cancers in a phase I clinical trial. To enhance the therapeutic efficacy of MDA-7 (IL-24), we engineered a designer cytokine (a "Superkine"; IL-24S; referred to as M7S) with enhanced secretion and increased stability to engender improved "bystander" antitumor effects. M7S was engineered in a two-step process by first replacing the endogenous secretory motif with an alternate secretory motif to boost secretion. Among four different signaling peptides, the insulin secretory motif significantly enhanced the secretion of MDA-7 (IL-24) protein and was chosen for M7S. The second modification engineered in M7S was designed to enhance the stability of MDA-7 (IL-24), which was accomplished by replacing lysine at position K122 with arginine. This engineered "M7S Superkine" with increased secretion and stability retained cancer specificity. Compared to parental MDA-7 (IL-24), M7S (IL-24S) was superior in promoting anti-tumor and bystander effects leading to improved outcomes in multiple cancer xenograft models. Additionally, combinatorial therapy using MDA-7 (IL-24) or M7S (IL-24S) with an immune checkpoint inhibitor, anti-PD-L1, dramatically reduced tumor progression in murine B16 melanoma cells. These results portend that M7S (IL-24S) promotes the re-emergence of an immunosuppressive tumor microenvironment, providing a solid rationale for prospective translational applications of this therapeutic designer cytokine.

Distinct hepatic immunological patterns are associated with the progression or inhibition of hepatocellular carcinoma.

To discover distinct immune responses promoting or inhibiting hepatocellular carcinoma (HCC), we perform a three-dimensional analysis of the immune cells, correlating immune cell types, interactions, and changes over time in an animal model displaying gender disparity in nonalcoholic fatty liver disease (NAFLD)-associated HCC. In response to a Western diet (WD), animals mount acute and chronic patterns of inflammatory cytokines, respectively. Tumor progression in males and females is associated with a predominant CD8+ > CD4+, Th1 > Th17 > Th2, NKT > NK, M1 > M2 pattern in the liver. A complete rescue of females from HCC is associated with an equilibrium Th1 = Th17 = Th2, NKT = NK, M1 = M2 pattern, while a partial rescue of males from HCC is associated with an equilibrium CD8+ = CD4+, NKT = NK and a semi-equilibrium Th1 = Th17 > Th2 but a sustained M1 > M2 pattern in the liver. Our data suggest that immunological pattern-recognition can explain immunobiology of HCC and guide immune modulatory interventions for the treatment of HCC in a gender-specific manner.

Pharmacological inhibition of MDA-9/Syntenin blocks breast cancer metastasis through suppression of IL-1ß.

Melanoma differentiation associated gene-9 (MDA-9), Syntenin-1, or syndecan binding protein is a differentially regulated prometastatic gene with elevated expression in advanced stages of melanoma. MDA-9/Syntenin expression positively associates with advanced disease stage in multiple histologically distinct cancers and negatively correlates with patient survival and response to chemotherapy. MDA-9/Syntenin is a highly conserved PDZ-domain scaffold protein, robustly expressed in a spectrum of diverse cancer cell lines and clinical samples. PDZ domains interact with a number of proteins, many of which are critical regulators of signaling cascades in cancer. Knockdown of MDA-9/Syntenin decreases cancer cell metastasis, sensitizing these cells to radiation. Genetic silencing of MDA-9/Syntenin or treatment with a pharmacological inhibitor of the PDZ1 domain, PDZ1i, also activates the immune system to kill cancer cells. Additionally, suppression of MDA-9/Syntenin deregulates myeloid-derived suppressor cell differentiation via the STAT3/interleukin (IL)-1ß pathway, which concomitantly promotes activation of cytotoxic T lymphocytes. Biologically, PDZ1i treatment decreases metastatic nodule formation in the lungs, resulting in significantly fewer invasive cancer cells. In summary, our observations indicate that MDA-9/Syntenin provides a direct therapeutic target for mitigating aggressive breast cancer and a small-molecule inhibitor, PDZ1i, provides a promising reagent for inhibiting advanced breast cancer pathogenesis.

Engineering T Cells to Express Tumoricidal MDA-7/IL24 Enhances Cancer Immunotherapy.

Antigen-specific immunotherapy can be limited by induced tumor immunoediting (e.g., antigen loss) or through failure to recognize antigen-negative tumor clones. Melanoma differentiation-associated gene-7/IL24 (MDA-7/IL24) has profound tumor-specific cytotoxic effects in a broad spectrum of cancers. Here we report the enhanced therapeutic impact of genetically engineering mouse tumor-reactive or antigen-specific T cells to produce human MDA-7/IL24. While mock-transduced T cells only killed antigen-expressing tumor cells, MDA-7/IL24-producing T cells destroyed both antigen-positive and negative cancer targets. MDA-7/IL24-expressing T cells were superior to their mock-engineered counterparts in suppressing mouse prostate cancer and melanoma growth as well as metastasis. This enhanced antitumor potency correlated with increased tumor infiltration and expansion of antigen-specific T cells as well as induction of a Th1-skewed immunostimulatory tumor environment. MDA-7/IL24-potentiated T-cell expansion was dependent on T-cell-intrinsic STAT3 signaling. Finally, MDA-7/IL24-modified T-cell therapy significantly inhibited progression of spontaneous prostate cancers in Hi-Myc transgenic mice. Taken together, arming T cells with tumoricidal and immune-potentiating MDA-7/IL24 confers new capabilities of eradicating antigen-negative cancer cell clones and improving T-cell expansion within tumors. This promising approach may be used to optimize cellular immunotherapy for treating heterogeneous solid cancers and provides a mechanism for inhibiting tumor escape. SIGNIFICANCE: This research describes a novel strategy to overcome the antigenic heterogeneity of solid cancers and prevent tumor escape by engineering T lymphocytes to produce a broad-spectrum tumoricidal agent.

Immunologically programming the tumor microenvironment induces the pattern recognition receptor NLRC4-dependent antitumor immunity.

BACKGROUND: The efficacy of cancer immunotherapy can be limited by the poor immunogenicity of cancer and the immunosuppressive tumor microenvironment (TME). Immunologically programming the TME and creating an immune-inflamed tumor phenotype is critical for improving the immune-responsiveness of cancers. Here, we interrogate the immune modulator Flagrp170, engineered via incorporation of a pathogen-associated molecular pattern (ie, flagellin) into an immunostimulatory chaperone molecule, in transforming poorly immunogenic tumors and establishing a highly immunostimulatory milieu for immune augmentation. METHODS: Multiple murine cancer models were used to evaluate the immunostimulatory activity, antitumor potency, and potential side effects of Flagrp170 on administration into the tumors using a replication impaired adenovirus. Antibody neutralization and mice deficient in pattern recognition receptors, that is, toll-like receptor 5 (TLR5) and NOD like receptor (NLR) family caspase activation and recruitment domain (CARD) domain-containing protein 4 (NLRC4), both of which can recognize flagellin, were employed to understand the immunological mechanism of action of the Flagrp170. RESULTS: Intratumoral delivery of mouse or human version of Flagrp170 resulted in robust inhibition of multiple malignancies including head and neck squamous cell carcinoma and breast cancer, without tissue toxicities. This in situ Flagrp170 treatment induced a set of cytokines in the TME known to support Th1/Tc1-dominant antitumor immunity. Additionally, granulocyte macrophage colony-stimulating factor derived from mobilized CD8+ T cells was involved in the therapeutic activity of Flagrp170. We also made a striking finding that NLRC4, not TLR5, is required for Flagrp170-mediated antitumor immune responses. CONCLUSION: Our results elucidate a novel immune-potentiating activity of Flagrp170 via engaging the innate pattern recognition receptor NLRC4, and support its potential clinical use to reshape cancer immune phenotype for overcoming therapeutic resistance.

Insights into the Mechanisms of Action of MDA-7/IL-24: A Ubiquitous Cancer-Suppressing Protein.

Melanoma differentiation associated gene-7/interleukin-24 (MDA-7/IL-24), a secreted protein of the IL-10 family, was first identified more than two decades ago as a novel gene differentially expressed in terminally differentiating human metastatic melanoma cells. MDA-7/IL-24 functions as a potent tumor suppressor exerting a diverse array of functions including the inhibition of tumor growth, invasion, angiogenesis, and metastasis, and induction of potent "bystander" antitumor activity and synergy with conventional cancer therapeutics. MDA-7/IL-24 induces cancer-specific cell death through apoptosis or toxic autophagy, which was initially established in vitro and in preclinical animal models in vivo and later in a Phase I clinical trial in patients with advanced cancers. This review summarizes the history and our current understanding of the molecular/biological mechanisms of MDA-7/IL-24 action rendering it a potent cancer suppressor.

"Double-punch" strategy for delivery of viral immunotherapy with prolonged tumor retention and enhanced transfection efficacy.

Viral immunotherapy has shown clinical efficacy in treating cancers (e.g., melanoma). Given that viral immunotherapy commonly uses intratumoral injection, prolonging the duration of therapeutic virus at the tumor site can further enhance the antitumor efficacy and reduce potential off-target effects. In this work, we describe a "double-punch" strategy by combining dendrimer platform and injectable hydrogel encapsulation for delivery of an adenovirus encoding Flagrp170 (Adv-Flagrp170), which has been shown to effectively mount a cytotoxic T lymphocyte response through enhanced tumor immunogenicity and optimized antigen cross-presentation. We first complexed PAMAM generation 4 (G4) with Adv (G4/Adv) to strengthen its transfection efficiency and then loaded G4/Adv into a biocompatible and injectable supramolecular hydrogel (SH) made of α-cyclodextrin and 4-arm polyethylene glycol via host-guest interaction. When tested in a murine melanoma model, the G4/Adv complex was shown to have improved retention at the tumor site. The presence of SH facilitated the targeted gene expression in tumor-infiltrating leukocytes, including antigen-presenting dendritic cells. Delivery of Adv-Flagrp170 by both G4 coating and SH encapsulation significantly enhanced its therapeutic efficacy in controlling mouse melanoma (8-fold reduction in tumor volume), which is associated with increased immune activation in the tumor microenvironment as well as decreased adenovirus-reactive antibodies. Taken together, this new formulation may be used to improve the treatment outcome of adenovirus-based cancer immunotherapy.

MDA-9/Syntenin (SDCBP): Novel gene and therapeutic target for cancer metastasis.

The primary cause of cancer-related death from solid tumors is metastasis. While unraveling the mechanisms of this complicated process continues, our ability to effectively target and treat it to decrease patient morbidity and mortality remains disappointing. Early detection of metastatic lesions and approaches to treat metastases (both pharmacological and genetic) are of prime importance to obstruct this process clinically. Metastasis is complex involving both genetic and epigenetic changes in the constantly evolving tumor cell. Moreover, many discrete steps have been identified in metastatic spread, including invasion, intravasation, angiogenesis, attachment at a distant site (secondary seeding), extravasation and micrometastasis and tumor dormancy development. Here, we provide an overview of the metastatic process and highlight a unique pro-metastatic gene, melanoma differentiation associated gene-9/Syntenin (MDA-9/Syntenin) also called syndecan binding protein (SDCBP), which is a major contributor to the majority of independent metastatic events. MDA-9 expression is elevated in a wide range of carcinomas and other cancers, including melanoma, glioblastoma multiforme and neuroblastoma, suggesting that it may provide an appropriate target to intervene in metastasis. Pre-clinical studies confirm that inhibiting MDA-9 either genetically or pharmacologically profoundly suppresses metastasis. An additional benefit to blocking MDA-9 in metastatic cells is sensitization of these cells to a second therapeutic agent, which converts anti-invasion effects to tumor cytocidal effects. Continued mechanistic and therapeutic insights hold promise to advance development of truly effective therapies for metastasis in the future.

Immunometabolism: A new target for improving cancer immunotherapy.

Fundamental metabolic pathways are essential for mammalian cells to provide energy, precursors for biosynthesis of macromolecules, and reducing power for redox regulation. While dysregulated metabolism (e.g., aerobic glycolysis also known as the Warburg effect) has long been recognized as a hallmark of cancer, recent discoveries of metabolic reprogramming in immune cells during their activation and differentiation have led to an emerging concept of "immunometabolism." Considering the recent success of cancer immunotherapy in the treatment of several cancer types, increasing research efforts are being made to elucidate alterations in metabolic profiles of cancer and immune cells during their interplays in the setting of cancer progression and immunotherapy. In this review, we summarize recent advances in studies of metabolic reprogramming in cancer as well as differentiation and functionality of various immune cells. In particular, we will elaborate how distinct metabolic pathways in the tumor microenvironment cause functional impairment of immune cells and contribute to immune evasion by cancer. Lastly, we highlight the potential of metabolically reprogramming the tumor microenvironment to promote effective and long-lasting antitumor immunity for improved immunotherapeutic outcomes.

Leutusome: A Biomimetic Nanoplatform Integrating Plasma Membrane Components of Leukocytes and Tumor Cells for Remarkably Enhanced Solid Tumor Homing.

Cell membrane-camouflaged nanoparticles have appeared as a promising platform to develop active tumor targeting nanomedicines. To evade the immune surveillance, we designed a composite cell membrane-camouflaged biomimetic nanoplatform, namely, leutusome, which is made of liposomal nanoparticles incorporating plasma membrane components derived from both leukocytes (murine J774A.1 cells) and tumor cells (head and neck tumor cells HN12). Exogenous phospholipids were used as building blocks to fuse with two cell membranes to form liposomal nanoparticles. Liposomal nanoparticles made of exogenous phospholipids only or in combination with one type of cell membrane were fabricated and compared. The anticancer drug paclitaxel (PTX) was used to make drug-encapsulating liposomal nanoparticles. Leutusome resembling characteristic plasma membrane components of the two cell membranes were examined and confirmed in vitro. A xenograft mouse model of head and neck cancer was used to profile the blood clearance kinetics, biodistribution, and antitumor efficacy of the different liposomal nanoparticles. The results demonstrated that leutusome obtained prolonged blood circulation and was most efficient accumulating at the tumor site (79.1 ± 6.6% ID per gram of tumor). Similarly, leutusome composed of membrane fractions of B16 melanoma cells and leukocytes (J774A.1) showed prominent accumulation within the B16 tumor, suggesting the generalization of the approach. Furthermore, PTX-encapsulating leutusome was found to most potently inhibit tumor growth while not causing systemic adverse effects.

Fatty acid oxidation: An emerging facet of metabolic transformation in cancer.

Cancer cells undergo metabolic reprogramming such as enhanced aerobic glycolysis, mutations in the tricarboxylic acid cycle enzymes, and upregulation of de novo lipid synthesis and glutaminolysis. These alterations are pivotal to the development and maintenance of the malignant phenotype of cancer cells in unfavorable tumor microenvironment or metastatic sites. Although mitochondrial fatty acid ß-oxidation (FAO) is a primary bioenergetic source, it has not been generally recognized as part of the metabolic landscape of cancer. The last few years, however, have seen a dramatic change in the view of cancer relevance of the FAO pathway. Many recent studies have provided significant evidence to support a "lipolytic phenotype" of cancer. FAO, like other well-defined metabolic pathways involved in cancer, is dysregulated in diverse human malignancies. Cancer cells rely on FAO for proliferation, survival, stemness, drug resistance, and metastatic progression. FAO is also reprogrammed in cancer-associated immune and other host cells, which may contribute to immune suppression and tumor-promoting microenvironment. This article reviews and puts into context our current understanding of multi-faceted roles of FAO in oncogenesis as well as anti-cancer therapeutic opportunities posed by the FAO pathway.