Improving combination therapies: targeting A2B-adenosine receptor to modulate metabolic tumor microenvironment and immunosuppression.

BACKGROUND: We investigated the role of A2B-adenosine receptor in regulating immunosuppressive metabolic stress in the tumor microenvironment. Novel A2B-adenosine receptor antagonist PBF-1129 was tested for antitumor activity in mice and evaluated for safety and immunologic efficacy in a phase I clinical trial of patients with non-small cell lung cancer. METHODS: The antitumor efficacy of A2B-adenosine receptor antagonists and their impact on the metabolic and immune tumor microenvironment were evaluated in lung, melanoma, colon, breast, and epidermal growth factor receptor-inducible transgenic cancer models. Employing electron paramagnetic resonance, we assessed changes in tumor microenvironment metabolic parameters, including pO2, pH, and inorganic phosphate, during tumor growth and evaluated the immunologic effects of PBF-1129, including its pharmacokinetics, safety, and toxicity, in patients with non-small cell lung cancer. RESULTS: Levels of metabolic stress correlated with tumor growth, metastasis, and immunosuppression. Tumor interstitial inorganic phosphate emerged as a correlative and cumulative measure of tumor microenvironment stress and immunosuppression. A2B-adenosine receptor inhibition alleviated metabolic stress, downregulated expression of adenosine-generating ectonucleotidases, increased expression of adenosine deaminase, decreased tumor growth and metastasis, increased interferon γ production, and enhanced the efficacy of antitumor therapies following combination regimens in animal models (anti-programmed cell death 1 protein vs anti-programmed cell death 1 protein plus PBF-1129 treatment hazard ratio = 11.74 [95% confidence interval = 3.35 to 41.13], n = 10, P < .001, 2-sided F test). In patients with non-small cell lung cancer, PBF-1129 was well tolerated, with no dose-limiting toxicities; demonstrated pharmacologic efficacy; modulated the adenosine generation system; and improved antitumor immunity. CONCLUSIONS: Data identify A2B-adenosine receptor as a valuable therapeutic target to modify metabolic and immune tumor microenvironment to reduce immunosuppression, enhance the efficacy of immunotherapies, and support clinical application of PBF-1129 in combination therapies.

Correction to: Determinant roles of dendritic cell-expressed Notch Delta-like and Jagged ligands on anti-tumor T-cell immunity.

Following publication of the original article [1], the author reported the wrong version of Figs. 5 and 7 have been published. The correct version of the figures can be found below.

Determinant roles of dendritic cell-expressed Notch Delta-like and Jagged ligands on anti-tumor T cell immunity.

BACKGROUND: Notch intercellular communication instructs tissue-specific T-cell development and function. In this study, we explored the roles of dendritic cell (DC)-expressed Notch ligands in the regulation of T-cell effector function. METHODS: We generated mice with CD11c lineage-specific deletion of Notch Delta-like ligand (Dll)1 and Jagged (Jag)2. Using these genetically-ablated mice and engineered pharmacological Notch ligand constructs, the roles of various Delta-like and Jagged ligands in the regulation of T-cell-mediated immunity were investigated. We assessed tumor growth, mouse survival, cytokine production, immunophenotyping of myeloid and lymphoid populations infiltrating the tumors, expression of checkpoint molecules and T-cell function in the experimental settings of murine lung and pancreatic tumors and cardiac allograft rejection. Correlative studies were also performed for the expression of NOTCH ligands, NOTCH receptors and PD-1 on various subsets of myeloid and lymphoid cells in tumor-infiltrating immune cells analyzed from primary human lung cancers. RESULTS: Mice with CD11c lineage-specific deletion of Notch ligand gene Dll1, but not Jag2, exhibited accelerated growth of lung and pancreatic tumors concomitant with decreased antigen-specific CD8+T-cell functions and effector-memory (Tem) differentiation. Increased IL-4 but decreased IFN-γ production and elevated populations of T-regulatory and myeloid-derived suppressor cells were observed in Dll1-ablated mice. Multivalent clustered DLL1-triggered Notch signaling overcame DC Dll1 deficiency and improved anti-tumor T-cell responses, whereas the pharmacological interference by monomeric soluble DLL1 construct suppressed the rejection of mouse tumors and cardiac allograft. Moreover, monomeric soluble JAG1 treatment reduced T-regulatory cells and improved anti-tumor immune responses by decreasing the expression of PD-1 on CD8+Tem cells. A significant correlation was observed between DC-expressed Jagged and Delta-like ligands with Tem-expressed PD-1 and Notch receptors, respectively, in human lung tumor-infiltrates. CONCLUSION: Our data show the importance of specific expression of Notch ligands on DCs in the regulation of T-cell effector function. Thus, strategies incorporating selectively engineered Notch ligands could provide a novel approach of therapeutics for modulating immunity in various immunosuppressive conditions including cancer.

Regulation of CX3CL1 Expression in Human First-Trimester Decidual Cells: Implications for Preeclampsia.

C-X3-C motif ligand 1 (CX3CL1) mediates migration, survival, and adhesion of natural killer (NK) cells, monocytes, and T-cells to endothelial/epithelial cells. Aberrant numbers and/or activation of these decidual immune cells elicit preeclampsia development. Decidual macrophages and NK cells are critical for implantation, while macrophage-derived tumor necrosis factor-α (TNF-α), interleukin-1 ß (IL-1ß), and NK cell-derived interferon-γ (IFN-γ) are associated with preeclampsia development. Thus, serum and decidual levels of CX3CL1 from first-trimester pregnancy and preeclampsia-complicated term pregnancy were examined by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. The effects of incubating primary human first-trimester decidual cells (FTDCs) with estradiol + medroxyprogesterone acetate + either IL-1ß or TNF-α and/or IFN-γ on CX3CL1 expression were also assessed by quantitative reverse transcription-polymerase chain reaction and ELISA. The inhibition of each signaling pathway with each kinase and nuclear factor κB (NFκB) inhibitors was evaluated by ELISA. Chemotaxis of CD56brightCD16- NK cells by various concentrations of CX3CL1 was evaluated. C-X3-C motif ligand 1 is expressed by both cytotrophoblasts and decidual cells in first-trimester decidua. C-X3-C motif ligand 1 expression is increased in term decidua but unchanged in first-trimester and term serum of patients with preeclampsia. Interferon-gamma and either IL-1ß or TNF-α synergistically upregulated CX3CL1 expression in FTDCs. Coincubation with IL-1ß or TNF-α or IFN-γ, mitogen-activated protein kinase kinase 1 and 2 (MEK1/2), c-JUN N-terminal kinase (JNK), and NFκB inhibitors suppressed CX3CL1 production. C-X3-C motif ligand 1 elicited concentration-dependent enhancement of CD56brightCD16- NK cell migration. In conclusion, the current study suggests that decidual cell-secreted CX3CL1 is involved in the later development of preeclampsia, whereas circulating CX3CL1 levels do not predict preeclampsia. Mitogen-activated protein kinase kinase 1 and 2, JNK, and NFκB signaling mediate IL-1ß-, TNF-α-, and IFN-γ-induced CX3CL1 production by FTDCs.

TriCurin, a synergistic formulation of curcumin, resveratrol, and epicatechin gallate, repolarizes tumor-associated macrophages and triggers an immune response to cause suppression of HPV+ tumors.

Our earlier studies reported a unique potentiated combination (TriCurin) of curcumin (C) with two other polyphenols. The TriCurin-associated C displays an IC50 in the low micromolar range for cultured HPV+ TC-1 cells. In contrast, because of rapid degradation in vivo, the TriCurin-associated C reaches only low nano-molar concentrations in the plasma, which are sub-lethal to tumor cells. Yet, injected TriCurin causes a dramatic suppression of tumors in TC-1 cell-implanted mice (TC-1 mice) and xenografts of Head and Neck Squamous Cell Carcinoma (HNSCC) cells in nude/nude mice. Here, we use the TC-1 mice to test our hypothesis that a major part of the anti-tumor activity of TriCurin is evoked by innate and adaptive immune responses. TriCurin injection repolarized arginase1high (ARG1high), IL10high, inducible nitric oxide synthaselow (iNOSlow), IL12low M2-type tumor-associated macrophages (TAM) into ARG1low, IL10low, iNOShigh, and IL12high M1-type TAM in HPV+ tumors. The M1 TAM displayed sharply suppressed STAT3 and induced STAT1 and NF-kB(p65). STAT1 and NF-kB(p65) function synergistically to induce iNOS and IL12 transcription. Neutralizing IL12 signaling with an IL12 antibody abrogated TriCurin-induced intra-tumor entry of activated natural killer (NK) cells and Cytotoxic T lymphocytes (CTL), thereby confirming that IL12 triggers recruitment of NK cells and CTL. These activated NK cells and CTL join the M1 TAM to elicit apoptosis of the E6+ tumor cells. Corroboratively, neutralizing IL12 signaling partially reversed this TriCurin-mediated apoptosis. Thus, injected TriCurin elicits an M2→M1 switch in TAM, accompanied by IL12-dependent intra-tumor recruitment of NK cells and CTL and elimination of cancer cells.

TriCurin, a novel formulation of curcumin, epicatechin gallate, and resveratrol, inhibits the tumorigenicity of human papillomavirus-positive head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide with about 600,000 new cases diagnosed in the last year. The incidence of human papillomavirus-positive head and neck squamous cell carcinoma (HPV-positive HNSCC) has rapidly increased over the past 30 years prompting the suggestion that an epidemic may be on the horizon. Therefore, there is a clinical need to develop alternate therapeutic strategies to manage the growing number of HPV-positive HNSCC patients. TriCurin is a composition of three food-derived polyphenols in unique stoichiometric proportions consisting of curcumin from the spice turmeric, resveratrol from red grapes, and epicatechin gallate from green tea. Cell viability, clonogenic survival, and tumorsphere formation were inhibited and significant apoptosis was induced by TriCurin in UMSCC47 and UPCI:SCC090 HPV-positive HNSCC cells. Moreover, TriCurin decreased HPV16E6 and HPV16E7 and increased p53 levels. In a pre-clinical animal model of HPV-positive HNSCC, intra-tumoral injection of TriCurin significantly inhibited tumor growth by 85.5% compared to vehicle group (P < 0.05, n = 7). Our results demonstrate that TriCurin is a potent anti-tumor agent for HPV-positive HNSCC. Further development of TriCurin as a novel anti-cancer therapeutic to manage the HPV-positive HNSCC population is warranted.

Modulation of Decidual Macrophage Polarization by Macrophage Colony-Stimulating Factor Derived from First-Trimester Decidual Cells: Implication in Preeclampsia.

During human pregnancy, immune tolerance of the fetal semiallograft occurs in the presence of abundant maternal leukocytes. At the implantation site, macrophages comprise approximately 20% of the leukocyte population and act as primary mediators of tissue remodeling. Decidual macrophages display a balance between anti-inflammatory and proinflammatory phenotypes. However, a shift to an M1 subtype is reported in preeclampsia. Granulocyte-macrophage colony-stimulating-factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) are major differentiating factors that mediate M1 and M2 polarization, respectively. Previously, we observed the following: i) the preeclamptic decidua contains an excess of both macrophages and GM-CSF, ii) the preeclampsia-associated proinflammatory cytokines, IL-1ß and tumor necrosis factor-α, markedly enhance GM-CSF and M-CSF expression in cultured leukocyte-free first-trimester decidual cells (FTDCs), iii) FTDC-secreted GM-CSF polarizes macrophages toward an M1 subtype. The microenvironment is a key determinant of macrophage phenotype. Thus, we examined proinflammatory stimulation of FTDC-secreted M-CSF and its role in macrophage development. Immunofluorescence staining demonstrated elevated M-CSF-positive decidual cell numbers in preeclamptic decidua. In FTDCs, IL-1ß and tumor necrosis factor-α signal through the NF-κB pathway to induce M-CSF production, which does the following: i) enhances differentiation of and elevates CD163 expression in macrophages, ii) increases macrophage phagocytic capacity, and iii) inhibits signal-regulatory protein α expression by macrophages. These findings suggest that FTDC-secreted M-CSF modulates the decidual immune balance by inducing M2 macrophage polarization and phagocytic capacity in response to proinflammatory stimuli.

Factors associated with successful transabdominal sonography-guided dilation and curettage for early cesarean scar pregnancy.

OBJECTIVE: To investigate factors associated with successful transabdominal sonography-guided dilation and curettage for the treatment of cesarean scar pregnancy (CSP). METHODS: In a retrospective study, data were reviewed from patients who received transabdominal sonography-guided dilation and curettage (TASDC) as the primary treatment for early CSP at The Second Xiangya Hospital, Changsha, China, between 2009 and 2013. RESULTS: Among 232 patients, 185 (79.7%) women with CSP were successfully treated with TASDC. Among them, 81 (43.8%) required insertion of a Foley catheter into the lower uterine segment to stop bleeding. The complication rate was 37.9% (88/232) and the failure rate was 21.3% (47/232). Overall, 28 (12.1%), 5 (2.2%), and 4 (1.7%) patients with massive intraoperative uterine bleeding were treated with wedge resection of the uterus, hysterectomy, and uterine artery embolization as a secondary treatment, respectively. In binary logistic regression analysis, pregnancy of 7 weeks or less and pregnancy without missed abortion were associated with successful TASDC for patients with CSP (P<0.001). CONCLUSION: Pregnancy of 7 weeks or less and pregnancy without missed abortion were found to be important factors for successful TASDC among patients with CSP. Wedge resection was the main secondary treatment to preserve the uterus and remove gestational tissue among patients with massive bleeding.

miR-124 Regulates the Epithelial-Restricted with Serine Box/Epidermal Growth Factor Receptor Signaling Axis in Head and Neck Squamous Cell Carcinoma.

Epithelial-restricted with serine box (ESX), a member of the ETS transcription factor family, is elevated and regulates EGFR in head and neck squamous cell carcinoma (HNSCC). However, the molecular mechanisms that contribute to ESX dysregulation remain to be elucidated. In this study, in silico analysis of the 3'-untranslated region (UTR) of ESX predicted two miR-124-binding sites. Delivery of miR-124 inhibited the 3'UTR ESX-driven reporter activity by 50% (P < 0.05) confirming ESX as a direct target of miR-124. Loss of miR-124 was found to be a frequent event in HNSCC. miR-124 expression was significantly depleted in the primary tumor compared with matched normal tissue in 100% (12/12) of HNSCC patients; relative mean miR-124 expression of 0.01197 and 0.00118 (P < 0.001, n = 12) in matched normal adjacent tissue and primary HNSCC tumor, respectively. Overexpression of miR-124 decreased ESX and EGFR levels in miR-124(low)/ESX(high)/EGFR(high) SCC15 HNSCC cells and reduced cell invasion, migration, proliferation, and colony formation. SCC15 cells with miR-124 restoration were less tumorigenic in vivo than miR-control SCC15 cells (70% inhibition, P < 0.01). Restoration of miR-124 in SCC15 cells enhanced the antiproliferative efficacy of the EGFR/Her2 tyrosine kinase inhibitors. Furthermore, recapitulation of EGFR in miR-124-overexpressing SCC15 cells was sufficient to completely block the antiproliferative effects of lapatinib and afatinib. Taken together, our work provides intriguing evidence that miR-124 is a novel therapeutic approach to reduce ESX/EGFR, and may be a tractable strategy to enhance the response rate of HNSCC patients to current anti-EGFR/Her2 therapies.

Expression of Interferon γ by Decidual Cells and Natural Killer Cells at the Human Implantation Site: Implications for Preeclampsia, Spontaneous Abortion, and Intrauterine Growth Restriction.

Human first-trimester decidual cells (FTDCs) chemoattract CXCR3-expressing circulating CD56(bright)CD16(-) natural killer (NK) cells, which increase uteroplacental blood flow by remodeling spiral arteries and arterioles. This recruitment reflects elevated FTDC expression of NK cell-recruiting induced protein 10 and interferon (IFN)-inducible T-cell-α chemoattractant produced in response to the synergistic effects of tumor necrosis factor α (TNF-α) and IFN-γ stimulation. Decidual macrophages express TNF-α, whereas the cellular origin of IFN-γ is unclear. Therefore, this study aims to identify the cell source(s) of IFN-γ in human first trimester decidua. Immunostaining of decidual sections revealed that both FTDCs and decidual NK (dNK) cells express IFN-γ. Although individual dNK cells express higher IFN-γ levels, the more numerous FTDCs account for greater proportion of total IFN-γ immunostaining. Freshly isolated FTDCs express greater IFN-γ staining than dNK cells as measured by flow cytometry, whereas incubation of dNK cells with documented NK cell activators significantly increases IFN-γ above FTDC levels. Confluent FTDCs intrinsically produce, but paradoxically respond to, exogenous IFN-γ.

Elevated intrinsic cancer stem cell population in human papillomavirus-associated head and neck squamous cell carcinoma.

BACKGROUND: Human papillomavirus 16 (HPV16) is a major risk factor for the development of head and neck squamous cell carcinoma (HNSCC), particularly the development of oropharyngeal squamous cell carcinoma (OPSCC). Cancer stem cells (CSCs) are resistant to conventional therapies, and it is postulated that they are responsible for disease recurrence and/or progression. Because the prognoses of patients with HPV16-positive and HPV-negative HNSCC are distinct, the authors sought to determine whether differences in the number of CSCs could account for this clinical observation. METHODS: CSC populations in HPV16-positive and HPV-negative HNSCC were assessed using a proprietary assay based on expression of the enzyme aldehyde dehydrogenase (ALDH), an in vitro tumorsphere formation assay, and an in vivo limiting cell dilution in nonobese diabetic/severe combined immunodeficiency mice. A high-density tissue microarray was stained with ALDH1, a CSC marker, to determine the association between CSCs and HPV16-positive/HPV-negative OPSCC. RESULTS: HPV16-positive HNSCC had a greater intrinsic CSC pool than HPV-negative HNSCC. Inactivation of p53 has been identified as a major mechanism for the elevated CSC population in HPV16-positive HNSCC. In vivo limiting cell dilution experiments using tumors from patients with HPV16-positive and HPV-negative OPSCC indicated that the CSC frequency was 62.5-fold greater in an HPV16-positive OPSCC tumor than in an HPV-negative OPSCC tumor. Primary tumors from patients with HPV16-positive OPSCC were associated with elevated tumor ALDH1 staining, further extending the association between HPV16 and CSCs. CONCLUSIONS: The current data and the clinical observation that patients with HPV16-positive HNSCC respond more favorably to current treatment paradigms than patients with HPV-negative HNSCC support the suggestion that CSC phenotype is not homogeneous. Therefore, the reliance on the CSC number may be insufficient to accurately assess the potential of a particular tumor for disease recurrence and/or progression.

Genetic and chemical targeting of epithelial-restricted with serine box reduces EGF receptor and potentiates the efficacy of afatinib.

EGF receptor (EGFR) is elevated in more than 90% of head and neck squamous cell carcinoma (HNSCC). However, a majority of patients with HNSCC do not respond to anti-EGFR therapeutics. Insensitivity to EGFR inhibitors may be due to kinase-independent actions of EGFR and/or activation of Her2. Strategies to reduce EGFR and Her2 protein levels in concert may be an optimal approach to enhance the efficacy of current anti-EGFR molecules. In this study, knockdown of epithelial-restricted with serine box (ESX) decreased EGFR and Her2 promoter activity, expression, and levels. ESX was elevated in primary HNSCC tumors and associated with increased EGFR and Her2. Genetic ablation of ESX decreased EGFR and Her2 levels and enhanced the antiproliferative effects of EGFR/Her2 tyrosine kinase inhibitors (TKI), lapatinib and afatinib. Biphenyl isoxazolidine, a novel small-molecule ESX inhibitor, reduced EGFR and Her2 levels and potentiated the antiproliferative efficacy of afatinib. Single-agent biphenyl isoxazolidine retarded the in vivo tumorigenicity of CAL27 cells. Importantly, the combination of biphenyl isoxazolidine and afatinib was significantly superior in vivo and resulted in a 100% response rate with a 94% reduction in tumor volume. Targeting EGFR/Her2 levels with an ESX inhibitor and EGFR/Her2 kinase activity with a TKI simultaneously is a highly active therapeutic approach to manage HNSCC. Our work provides evidence to support the further development of ESX inhibitors as an adjuvant to enhance the response rate of patients with HNSCC to current anti-EGFR/Her2 therapeutics.

Human serum albumin-coated lipid nanoparticles for delivery of siRNA to breast cancer.

Human serum albumin (HSA)-coated lipid nanoparticles (HSA-LNPs) loaded with phrGFP-targeted siRNA (HSA-LNPs-siRNA) were prepared and evaluated for gene downregulation effect in phrGFP-transfected breast cancer cells and the corresponding xenograft tumor model. HSA-LNPs-siRNA were successfully prepared with a particle size of 79.5±5.5 nm. In phrGFP-transfected MCF-7 cells, HSA-LNPs-siRNA significantly decreased cell fluorescence even in the presence of fetal bovine serum (FBS). Moreover, cell fluorescence and phrGFP mRNA expression were significantly downregulated by HSA-LNPs-siRNA in phrGFP-transfected MCF-7, MDA-MB-231, and SK-BR-3 cells in comparison with control or HSA-LNPs-siRNA (scrambled). In phrGFP-transfected MCF-7 xenograft tumor model, tumor fluorescence was significantly decreased after three IV administrations of HSA-LNPs-siRNA at a dose of 3 mg/kg in comparison with siRNA alone. HSA-LNPs-siRNA demonstrated a superior pharmacokinetic profile in comparison with siRNA at a dose of 1mg/kg. These results show that the novel nonviral carrier, HSA-LNPs, may be used for the delivery of siRNA to breast cancer cells. FROM THE CLINICAL EDITOR: Targeted delivery of siRNA to cancer cells may be a viable anti-cancer strategy with low toxicity. In this study the novel nonviral carrier, human serum albumin-coated lipid nanoparticles (HSA-LNP) were demonstrated as an efficient delivery agent of siRNA to breast cancer cells.

Lipid-based nanoparticle delivery of Pre-miR-107 inhibits the tumorigenicity of head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide with about 600,000 new cases diagnosed in the last year. Our laboratory showed that miR-107 expression is reduced and functions as a tumor suppressor gene in HNSCC suggesting the potential application of miR-107 as a novel anticancer therapeutic. In this study, we determined the efficiency and efficacy of cationic lipid nanoparticles to deliver pre-miR-107 (NP/pre-miR-107) in HNSCC cells in vitro and in vivo. NP/pre-miR-107 increased delivery of miR-107 into HNSCC cells by greater than 80,000-fold compared to free pre-miR-107. Levels of known miR-107 targets, protein kinase Cε (PKCε), cyclin-dependent kinase 6 (CDK6), and hypoxia-inducible factor 1-ß (HIF1-ß), decreased following NP/pre-miR-107 treatment. Clonogenic survival, cell invasion, and cell migration of HNSCC cells was inhibited with NP/pre-miR-107. Moreover, NP/pre-miR-107 reduced the cancer-initiating cell (CIC) population and dampened the expression of the core embryonic stem cell transcription factors, Nanog, Oct3/4, and Sox2. In a preclinical mouse model of HNSCC, systemic administration of NP/pre-miR-107 significantly retarded tumor growth by 45.2% compared to NP/pre-miR-control (P < 0.005, n = 7). Kaplan-Meier analysis showed a survival advantage for the NP/pre-miR-107 treatment group (P = 0.017). Our results demonstrate that cationic lipid nanoparticles are an effective carrier approach to deliver therapeutic miRs to HNSCC.

Delivery of calf thymus DNA to tumor by folate receptor targeted cationic liposomes.

Calf thymus DNA (ctDNA) has been shown to stimulate macrophages to produce cytokines both in vitro and in vivo when complexed with cationic liposomes. In addition, direct cytotoxicity of ctDNA has been found in tissue culture and in mice. In this study, ctDNA and folate receptor targeted cationic liposome complexes (ctDNA-F-CLs) were prepared and evaluated in FR (+) tumors. In addition, the underlying mechanism for the anti-cancer activity of ctDNA-F-CLs was investigated. Selective uptake of ctDNA-F-CLs was observed in FR (+) KB and L1210JF cells using flow cytometry. In RAW264.7 cells and DBA/2 mice, ctDNA-F-CLs and ctDNA-N-CLs significantly induced TNF-α and IL-6 production compared to free ctDNA. However, no significant difference in cytokine production was observed between ctDNA-N-CLs and ctDNA-F-CLs. In tumor bearing DBA/2 mice, ctDNA-F-CLs significantly increased INF-γ and IL-6 production compared to ctDNA-N-CLs. Furthermore in L1210JF cells, ctDNA-F-CLs had significantly increased cytotoxicity compared to ctDNA-N-CLs. Tumor cell apoptosis was also found in co-culture of RAW264.7 cells and ctDNA-F-CLs treated L1210JF cells. In L1210JF tumor bearing mice, ctDNA-F-CLs were found to significantly inhibit tumor growth and prolong the median survival time (MeST). In contrast, ctDNA-N-CLs and free ctDNA showed similar activities for tumor inhibition and animal survival. Moreover, the anti-cancer effect of ctDNA-F-CL was further enhanced by combination with anti-cancer drug doxorubicin. These results suggest that ctDNA-F-CLs are a promising agent for treatment of FR-positive tumors.

Liposomes containing (-)-gossypol-enriched cottonseed oil suppress Bcl-2 and Bcl-xL expression in breast cancer cells.

PURPOSE: We have demonstrated that (-)-gossypol-enriched cottonseed oil [(-)-GPCSO] can down-regulate Bcl-2 expression in MCF-7 and primary cultured human breast cancer epithelial cells (PCHBCECs). However, this agent has not been evaluated in vivo due to its limited solubility. We aimed to develop liposomes containing (-)-GPCSO to suppress Bcl-2/Bcl-xL expression. METHODS: (-)-GPCSO liposomes were prepared and evaluated for effects on breast cancer cell viability, MDA-MB-231 xenograft tumor growth, cellular Bcl-2 and Bcl-xL mRNA levels, and chemosensitivity to paclitaxel. RESULTS: (-)-GPCSO liposomes prepared had excellent stability. Cytotoxicity of (-)-GPCSO liposomes was significantly reduced compared to (-)-GPCSO in culture medium. Bcl-2 and Bcl-xL mRNA expression was down-regulated by (-)-GPCSO in culture medium or (-)-GPCSO liposomes in MDA-MB-231 cells. In PCHBCECs, Bcl-2 and Bcl-xL expression were down-regulated by (-)-GPCSO liposomes. (-)-GPCSO in culture medium induced only a mild reduction in Bcl-xL. In the MDA-MB-231 xenograft tumor model, (-)-GPCSO liposomes exhibited tumor-suppressive activity and significantly reduced intratumoral Bcl-2 and Bcl-xL expression. Cytotoxicity of paclitaxel was increased by pretreatment with (-)-GPCSO liposomes in MDA-MB-231 and PCHBCECs. CONCLUSIONS: Findings suggest that (-)-GPCSO liposomes warrant continued investigation as a chemosensitizer for breast cancers exhibiting Bcl-2-/Bcl-xL-mediated drug resistance.

Targeting human clonogenic acute myelogenous leukemia cells via folate conjugated liposomes combined with receptor modulation by all-trans retinoic acid.

Our previous data demonstrated that folate receptor ß (FR-ß) targeted liposomal doxorubicin (FT-L-DOX) showed enhanced cytotoxicity relative to non-targeted liposomal doxorubicin (CON-L-DOX), and the effect was enhanced by selective FR-ß upregulation by all-trans retinoic acid (ATRA) in AML blast cells. In this study, the enhanced cytotoxicity was investigated in the proliferating human AML clonogenic cells by combining FT-L-DOX with ATRA. Also, pharmacokinetic properties by pretreatment of ATRA were evaluated using FR-targeted liposomal calcein (FT-L-Calcein). Pharmacokinetic study showed that the area under the concentration curve (AUC) of FT-L-Calcein was decreased and total clearance was increased by pretreatment with ATRA. Meanwhile, the volume of distribution was significantly increased by pretreatment of ATRA. Moreover, calcein level in the liver, spleen and kidney was increased following intravenous administration of FT-L-Calcein by pretreatment of ATRA. In vitro cytotoxicity of FT-L-DOX was higher than that of CON-L-DOX and was increased by pretreatment with ATRA. Colony formation in AML cells was lower due to treatment with FT-L-DOX compared with CON-L-DOX and colony formation further decreased upon pretreatment with ATRA. Moreover, FT-L-DOX was more toxic to AML clonogenic cells than to AML blast cells. The results demonstrate that the efficiency of FR-mediated targeting of FT-L-DOX was preferentially enhanced by ATRA induced FR-ß upregulation in AML clonogenic cells.

Folate-immunoglobulin G as an anticancer therapeutic antibody.

Folate receptor-alpha (FR) is a promising cellular marker for tumor-specific drug delivery. Conjugation of folic acid to therapeutic and imaging agents has been shown to enhance their delivery to FR (+) cancer cells in vitro and in tumor-bearing mice via an FR-mediated cellular uptake mechanism. In this study, immunoglobulin G (IgG) was conjugated to folate and evaluated as a therapeutic antibody against folate receptor (FR)-positive tumors. Murine IgG (mIgG) was conjugated to folate via an amide bond to yield folate-conjugated mIgG (f-mIgG) that contained an average of approximately 2.6 folates per molecule. Selective uptake of f-IgG by FR (+) tumor cells was determined by fluorescence microscopy and by flow cytometry. Lysis of L1210JF cells by NK cells from murine donors was increased 1.4-9.0-fold at the effector:target (E:T) ratio of 25:1, relative to control mIgG. In mice bearing L1210JF tumors, f-mIgG was found to significantly inhibit tumor growth and to have prolonged the median survival time (MeST). Significantly, the antitumor efficacy of f-mIgG was greatly increased when combined with liposomal G3139, an 18-mer phosphorothioate oligonucleotide. In fact, the combination resulted in a 100% cure rate among the tumor-bearing mice. Injection of f-mIgG significantly increased serum INF-gamma and IL-6 level in mice compared with mIgG and dramatically increased serum INF-gamma and IL-6 level when combined with liposomal G3139. These results suggested that f-IgG, a novel immunotherapy agent, has potent activity as a therapeutic antibody to the FR-positive cancer, and the therapeutic activity is enhanced by immunomodulatory agents.

Transferrin-conjugated lipid-coated PLGA nanoparticles for targeted delivery of aromatase inhibitor 7alpha-APTADD to breast cancer cells.

Transferrin (Tf)-conjugated lipid-coated poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles carrying the aromatase inhibitor, 7alpha-(4'-amino)phenylthio-1,4-androstadiene-3,17-dione (7alpha-APTADD), were synthesized by a solvent injection method. Formulation parameters including PLGA-to-lipid, egg PC-to-TPGS, and drug-to-PLGA ratios and aqueous-to-organic phase ratio at the point of synthesis were optimized to obtain nanoparticles with desired sizes and drug loading efficiency. The optimal formulation had a drug loading efficiency of 36.3+/-3.4%, mean diameter of 170.3+/-7.6nm and zeta potential of -18.9+/-1.5mV. The aromatase inhibition activity of the nanoparticles was evaluated in SKBR-3 breast cancer cells. IC(50) value of the Tf-nanoparticles was ranging from 0.77 to 1.21nM, and IC(50) value of the nanoparticles was ranging from 1.90 to 3.41nM (n=3). The former is significantly lower than the latter (p<0.05). These results suggested that the aromatase inhibition activity of the Tf-nanoparticles was enhanced relative to that of the non-targeted nanoparticles, which was attributable to Tf receptor (TfR) mediated uptake. In conclusion, Tf-conjugated lipid-coated PLGA nanoparticles are potential vehicles for improving the efficiency and specificity of therapeutic delivery of aromatase inhibitors.

Preparation, characterization and pharmacokinetics of folate receptor-targeted liposomes for docetaxel delivery.

A novel liposomal formulation of docetaxel targeting the folate receptor (FR) was synthesized and characterized. Liposomal formulations are less toxic and can provide longer systemic circulation time than the Tween 80 and ethanol based clinical formulation of docetaxel. Folate receptor-alpha (FR) is frequently over-expressed on epithelial cancer cells. Therefore, FR targeted liposomes can potentially enhance tumor cell uptake and antitumor efficacy of encapsulated drugs. The formulation studied had the compositions of egg phosphatidylcholine/cholesterol/methoxy-polyethylene glycol (PEG)2,000-distearoylphosphatidylethanolamine/folate-PEG3,350-cholesteryl hemisuccinate (ePC/Chol/mPEG-DSPE/folate-PEG-CHEMS) at ratios of (80:15:4.5:0.5, mol/mol) and a drug-to-lipid ratio of 1:20, wt/wt. Sucrose was used as a lyoprotectant. The liposomes were prepared by thin-film hydration, polycarbonate membrane extrusion, followed by lyophilization. They remained stable for more than 5 months when stored as lyophilized powder and for 72 h at 4 degrees C following rehydration. The mean particle size of reconstituted liposomes ranged from 110 to 120 nm. FR-targeted liposomes of the same lipid composition entrapping calcein were shown to be efficiently taken up by FR + KB oral carcinoma cells. FR-targeted liposomes containing docetaxel showed 4.4-fold greater cytotoxicity compared to non-targeted liposomes in KB cells. Plasma clearance profiles of FR-targeted and non-targeted liposomeal docetaxel were evaluated and compared with that of docetaxel in Tween 80/ethanol formulation. The liposomal formulations showed much longer terminal half lives (4.92 h and 6.75 h for FR-targeted and non-targeted, respectively) than docetaxel in Tween 80/ethanol solution (1.09 h). FR-targeted liposomes are promising tumor cell-selective nanocarriers for docetaxel with potential for therapeutic applications.