Therapeutic effect of dichloroacetate against atherosclerosis via hepatic FGF21 induction mediated by acute AMPK activation

Dyslipidemia-induced atherosclerosis, which has a risk of high morbidity and mortality, can be alleviated by metabolic activation associated with mitochondrial function. The effect of dichloroacetate (DCA), a general pyruvate dehydrogenase kinase (PDK) inhibitor, on in vivo energy expenditure in ApoE-/- mice fed a western diet (WD) has not yet been investigated. WD-fed ApoE-/- mice developed atherosclerotic plaques and hyperlipidemia along with obesity, which were significantly ameliorated by DCA administration. Increased oxygen consumption was associated with heat production in the DCA-treated group, with no change in food intake or physical activity compared with those of the control. These processes were correlated with the increased gene expression of Dio2 and Ucp-1, which represents brown adipose tissue (BAT) activation, in both WD-induced atherosclerosis and high-fat-induced obesity models. In addition, we found that DCA stimulated hepatic fibroblast growth factor 21 (Fgf21) mRNA expression, which might be important for lowering lipid levels and insulin sensitization via BAT activation, in a dose- and time-dependent manner associated with serum FGF21 levels. Interestingly, Fgf21 mRNA expression was mediated in an AMP-activated protein kinase (AMPK)-dependent manner within several minutes after DCA treatment independent of peroxisome proliferator-activated receptor alpha (PPARα). Taken together, the results suggest that enhanced glucose oxidation by DCA protects against atherosclerosis by inducing hepatic FGF21 expression and BAT activation, resulting in augmented energy expenditure for heat generation.

Pyruvate Dehydrogenase Kinase Is a Metabolic Checkpoint for Polarization of Macrophages to the M1 Phenotype

Metabolic reprogramming during macrophage polarization supports the effector functions of these cells in health and disease. Here, we demonstrate that pyruvate dehydrogenase kinase (PDK), which inhibits the pyruvate dehydrogenase-mediated conversion of cytosolic pyruvate to mitochondrial acetyl-CoA, functions as a metabolic checkpoint in M1 macrophages. Polarization was not prevented by PDK2 or PDK4 deletion but was fully prevented by the combined deletion of PDK2 and PDK4; this lack of polarization was correlated with improved mitochondrial respiration and rewiring of metabolic breaks that are characterized by increased glycolytic intermediates and reduced metabolites in the TCA cycle. Genetic deletion or pharmacological inhibition of PDK2/4 prevents polarization of macrophages to the M1 phenotype in response to inflammatory stimuli (lipopolysaccharide plus IFN-γ). Transplantation of PDK2/4-deficient bone marrow into irradiated wild-type mice to produce mice with PDK2/4-deficient myeloid cells prevented M1 polarization, reduced obesity-associated insulin resistance, and ameliorated adipose tissue inflammation. A novel, pharmacological PDK inhibitor, KPLH1130, improved high-fat diet-induced insulin resistance; this was correlated with a reduction in the levels of pro-inflammatory markers and improved mitochondrial function. These studies identify PDK2/4 as a metabolic checkpoint for M1 phenotype polarization of macrophages, which could potentially be exploited as a novel therapeutic target for obesity-associated metabolic disorders and other inflammatory conditions.

PDK4 Deficiency Suppresses Hepatic Glucagon Signaling by Decreasing cAMP Levels

In fasting or diabetes, gluconeogenic genes are transcriptionally activated by glucagon stimulation of the cAMP-protein kinase A (PKA)-CREB signaling pathway. Previous work showed pyruvate dehydrogenase kinase (PDK) inhibition in skeletal muscle increases pyruvate oxidation, which limits the availability of gluconeogenic substrates in the liver. However, this study found upregulation of hepatic PDK4 promoted glucagon-mediated expression of gluconeogenic genes, whereas knockdown or inhibition of hepatic PDK4 caused the opposite effect on gluconeogenic gene expression and decreased hepatic glucose production. Mechanistically, PDK4 deficiency decreased ATP levels, thus increasing phosphorylated AMPK (p-AMPK), which increased p-AMPK-sensitive phosphorylation of cyclic nucleotide phosphodiesterase 4B (p-PDE4B). This reduced cAMP levels and consequently p-CREB. Metabolic flux analysis showed that the reduction in ATP was a consequence of a diminished rate of fatty acid oxidation (FAO). However, overexpression of PDK4 increased FAO and increased ATP levels, which decreased p-AMPK and p-PDE4B and allowed greater accumulation of cAMP and p-CREB. The latter were abrogated by the FAO inhibitor etomoxir, suggesting a critical role for PDK4 in FAO stimulation and the regulation of cAMP levels. This finding strengthens the possibility of PDK4 as a target against diabetes.

Identification of Selective ERRγ Inverse Agonists

GSK5182 (4) is currently one of the lead compounds for the development of estrogen-related receptor gamma (ERRγ) inverse agonists. Here, we report the design, synthesis, pharmacological and in vitro absorption, distribution, metabolism, excretion, toxicity (ADMET) properties of a series of compounds related to 4. Starting from 4, a series of analogs were structurally modified and their ERRγ inverse agonist activity was measured. A key pharmacophore feature of this novel class of ligands is the introduction of a heterocyclic group for A-ring substitution in the core scaffold. Among the tested compounds, several of them are potent ERRγ inverse agonists as determined by binding and functional assays. The most promising compound, 15g, had excellent binding selectivity over related subtypes (IC₅₀ = 0.44, >10, >10, and 10 μM at the ERRγ, ERRα, ERRβ, and ERα subtypes, respectively). Compound 15g also resulted in 95% transcriptional repression at a concentration of 10 μM, while still maintaining an acceptable in vitro ADMET profile. This novel class of ERRγ inverse agonists shows promise in the development of drugs targeting ERRγ-related diseases.

The utilisation of Complementary and Alternative Medicine (CAM) among ethnic minorities in South Korea

Background

Race has been reported to affect the use of complementary and alternative medicine (CAM), but there is very little research on the use of CAM by ethnicity in Korea. This study explores the prevalence of CAM use among ethnic minorities in South Korea.

Methods

The design is a descriptive and cross-sectional study. A convenience sample of ethnic minorities was recruited from two public healthcare centres in Gyeonggi province. The survey instrument included 37 questions regarding CAM use, factors influencing use of CAM, self-health management, and the socio-demographic profile of study participants.

Results

Sixty-two percent of study participants reported the use of CAM. Multivitamins (53.3%), acupuncture (48.9%), and traditional Korean herbal medicine (38.9%) were popular CAM modalities in our sample. Other notable CAM modalities included herbal plants, therapeutic massage, and moxibustion therapy. The majority of CAM users (52.2%) received CAM services to treat diseases or as a secondary treatment while receiving conventional care. Having positive perceptions toward the effectiveness of CAM was a major determining factor in CAM use.

Conclusions

Physicians need to be aware of the fact that many ethnic minorities use CAM therapies. Many CAM users reported that they want doctors to know about their CAM use and have a basic understanding of traditional medicine in their home country. Overcoming language and cultural barriers will help reduce unwanted medical complications. High prevalence of CAM use among ethnic minorities in our study warrants further studies using larger sample population.

Abstract 610: Metformin augments rituximab and chemotherapeutic agents-induced apoptosis via mTOR inhibition in rituximab-resistant B lymphoma cell lines

With elusive mechanisms, a subgroup of NHL patients who treated with rituximab in combination with cytotoxic chemotherapeutic agents becomes unresponsive. Patients who relapsed lymphoma are known to have poorer outcome when treated with rituximab compared with treated without rituximab. Since activation of mTOR pathway has been recently suggested for progression of NHL, especially in salvage setting, we'd like to examine the effect of metformin which inhibits mTOR pathway in rituximab-resistant NHL. Three lymphoma cell lines (Raji, Raji-2R, Raji-4RH) were used, which were kindly given by Dr Czuczman MS from Rosewell Park Cancer Institute (Ref. Czuczmana MS et al. Clin Cancer Res 2008;14:1561, 2008;14:1550). These cells were treated with cisplatin, adriamycin, vincristine and rituximab in the absence or presence of metformin for 24, 48, 72 hrs. Cell growth and proliferation was evaluated by MTT assay and cell cycle progression was determined FACS analysis. To characterize molecular mechanisms involved in metformin-induced inhibition of cell proliferation, the level of BAX, BAK, Bcl-2, Bcl-XL, Mcl-1, AMPK, pAMPK, pACC, mTOR, p70S6K and S6K was determined by western blot analysis.

Compared with rituximab-sensitive cell line (RSCL) which is parental lymphoma cell, Raji, rituximab-resistant cell lines (RRCLs), that are Raji-2R and Raji-4RH, have shown decreased cytotoxicity in response to chemotherapeutic agents including cisplatin, adriamycin and vincristine as well as rituximab. However, cytotoxic effect of these chemotherapeutic agents and rituximab was improved in combination of metformin in both RSCL and RRCLs. To us surprise, a better synergistic inhibition of cell proliferation was found in RRCLs as a result of combination of metformin and chemotherapeutic agents or rituximab, suggesting that intracellular signaling pathway induced by metformin might not be overlapped to that by chemotherapeutic agent and rituximab. Notably, it has known that in RRCLs, the level of proapototic proteins, BAX, BAK, is relatively low compared to in RSCL decreased, but the expression of anti-apoptotic protein and AMPK activity is increased and dysregulation of mTOR pathway is found. Our data showed that metformin restored dysregulation of mTOR pathway in RRCLs, since activation of p70S6K and S6K posphorylation was decreased. At the same time, expression of BAX and BAK was increased and that of anti-apoptotic proteins was decreased.

Metformin enhances rituximab-induced and chemotherapy-induced apoptosis via mTOR inhibition in rituximab-resistant NHL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 610.

Complete molecular remission during biologic response modifier therapy for Sézary syndrome is associated with enhanced helper T type 1 cytokine production and natural killer cell activity

BACKGROUND

Cutaneous T-cell lymphoma (CTCL) is a clonally derived, skin-invasive malignancy of CD4(+) T lymphocytes with the phenotype of mature helper T cells. Advancing stages of CTCL are associated with depressed cell-mediated immunity, increased production of T helper type 2 cytokines and decreased levels of T helper type 1 cytokines.

OBJECTIVE

Our purpose was to evaluate the cytokine secretion pattern and cell-mediated cytotoxicity in peripheral blood mononuclear cells of patients with Sézary syndrome in relation to the presence of the malignant clone.

METHODS

Serial polymerase chain reaction for the T-cell receptor-beta or T-cell receptor-gamma gene rearrangement was used to determine the presence of the malignant clone. Enzyme-linked immunosorbent assays were used to determine the levels of interleukin 4 and interferon gamma produced by the peripheral blood mononuclear cells from the patients with Sézary syndrome.

RESULTS

We demonstrate 3 cases of Sézary syndrome with typically suppressed cell-mediated cytotoxicity, elevated production of interleukin 4, and depressed production of interferon gamma by their peripheral blood mononuclear cells before institution of therapy with biologic response modifier therapy. In all 3 cases after clinical and molecular remission, we observed striking immunologic changes, including an increase in levels of natural killer cell activity and interferon gamma production and decreased production of interleukin 4.

CONCLUSIONS

The observation that the cytokine secretion pattern by peripheral blood mononuclear cells from 3 patients with Sézary syndrome normalized with the disappearance of the malignant clone from the peripheral blood suggests that the malignant T cells account for the aberrant cytokine production. Moreover, the aberrant cytokine production may be the cause for suppression of cell-mediated immunity seen in advancing stages of CTCL.

Photopheresis: clinical applications and mechanism of action

Photopheresis is a leukapheresis-based therapy that utilizes 8-methoxypsoralen and ultraviolet A irradiation. Photopheresis is currently available at approximately 150 medical centers worldwide. Recent evidence suggests that this therapy used as a single agent may significantly prolong life, as well as induce a 50%-75% response rate among individuals with advanced cutaneous T cell lymphoma (CTCL). Furthermore, a 20%-25% complete response rate with photopheresis alone, or in combination with other biologic response modifiers, has been obtained at our institution among patients with Sezary syndrome. These complete responses have been characterized by the complete disappearance of morphologically atypical cells from the skin and blood. The use of sensitive molecular techniques has also confirmed the sustained disappearance of the malignant T cell clone from the blood of patients with complete responses. In addition to the treatment of CTCL, numerous reports indicate that photopheresis is a potent agent in the therapy of acute allograft rejection among cardiac, lung, and renal transplant recipients. Chronic graft versus host disease also appears to be quite responsive to photopheresis therapy. Likewise, there may also be a potential role for photopheresis in the therapy of certain autoimmune diseases that are poorly responsive to conventional therapy. The immunologic basis for the responses of patients with these conditions is likely due to the induction of anticlonotypic immunity directed against pathogenic clones of T lymphocytes. Treatment-induced apoptotic death of pathogenic T cells and activation of antigen presenting cells are postulated to have important effects in this therapeutic process.

Interleukin-12 therapy of cutaneous T-cell lymphoma induces lesion regression and cytotoxic T-cell responses

Progression of cutaneous T-cell lymphoma (CTCL) is associated with profound defects in cell-mediated immunity and depressed production of cytokines, which support cell-mediated immunity. Because we have observed marked defects in interleukin-12 (IL-12) production in CTCL and because IL-12 is critical for antitumor cytotoxic T-cell responses, we initiated a phase I dose escalation trial with recombinant human IL-12 (rhIL-12) where patients received either 50, 100, or 300 ng/kg rhIL-12 twice weekly subcutaneously or intralesionally for up to 24 weeks. Ten patients were entered: 5 with extensive plaque, 3 with Sezary syndrome, and 2 with extensive tumors with large cell transformation. One patient with Sezary syndrome dropped out after 1 week for personal reasons. Subcutaneous dosing resulted in complete responses (CR) in 2 of 5 plaque and partial responses (PR) in 2 of 5 plaque, and 1 of 2 Sezary syndrome (overall response rate CR+PR 5 of 9, 56%). A minor response also occurred in 1 of 5 plaque patients. Intralesional dosing resulted in individual tumor regression in 2 of 2 patients. Biopsy of regressing lesions showed a significant decrease in the density of the infiltrate in all cases and complete resolution of the infiltrate among those with clinical lesion resolution. An increase in numbers of CD8-positive and/or TIA-1-positive T cells were observed on immunohistochemical analysis of skin biopsy specimens obtained from regressing skin lesions. Adverse effects of rhIL-12 on this regimen were minor and limited and included low-grade fever and headache. One patient discontinued rhIL-12 at week 6 because of depression. These results suggest that rhIL-12 may augment antitumor cytotoxic T-cell responses and may represent a potent and well-tolerated therapeutic agent for CTCL.

Use of biological response modifiers in the treatment of cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is typically a skin-infiltrating, clonal proliferative disorder of CD4+ T cells that exhibit a T-helper type 2 cytokine phenotype. Therapeutic decisions are based on the extent of disease and the observations that host-antitumor responses occur and that these responses may be blunted by the immunosuppressive cytokines produced by the malignant T cells. Biologic response modifiers, which may enhance cell-mediated immunity and antitumor responses, are active agents in the treatment of CTCL. The rationale and use of biologic response modifiers to treat CTCL are reviewed in this article.

Apoptosis induction of ultraviolet light A and photochemotherapy in cutaneous T-cell Lymphoma: relevance to mechanism of therapeutic action

The anti-tumor action of many chemotherapeutic agents has recently been attributed to the induction of apoptosis in the malignant cell population. In this study, we investigated the ability of extracorporeal photopheresis (ExP) and in vitro PUVA (8-methoxy-psoralen + ultraviolet A) therapy to induce apoptosis in peripheral blood mononuclear cells from Sezary syndrome patients and normal controls. Flow cytometric analysis of ExP- or PUVA-treated peripheral blood lymphocytes demonstrated two distinct cell populations within 24 h of treatment. One population was similar to untreated controls with the other exhibiting characteristics of apoptotic cell death, i.e., a loss of cell volume and an accompanying increase in cell density. This latter population was comprised of cells with DNA strand breaks as determined by the Tdt-mediated deoxyuridine triphosphate-biotin nick end labeling assay. Apoptosis was also confirmed morphologically by fluorescent and electron microscopy as well as by demonstration of characteristic DNA strand breaks (laddering) using gel electrophoresis. Apoptosis was not observed with 8-methoxypsoralen (< or = 300 ng per ml) alone; however, ultraviolet A alone at doses > or = 2 J per cm2 induced apoptosis in lymphocytes. Peripheral blood T-cell subpopulations of Sezary syndrome patients, including the malignant clone, were equally susceptible to apoptosis subsequent to either photopheresis or PUVA treatment. In contrast, monocytes (CD14+/CD45+) appear to be resistant to apoptosis induction by ExP or PUVA treatment. Moreover, ExP-treated and untreated monocytes phagocytized apoptotic, but not untreated, peripheral blood mononuclear cells. ExP and PUVA have been shown to be efficacious and well-tolerated therapies in the treatment of dermatologic diseases and transplant rejection. These data suggest that induction of apoptosis may be an important event for therapeutic efficacy.

Kinetic analysis of apoptosis induction in human cell lines by UVA and 8-MOP

Whereas previous studies have indicated that DNA damage as a result of 8-methoxypsoralen (8-MOP) and UVA treatment leads to cell death, this study establishes the minimum concentrations of 8-MOP and UVA necessary to induce apoptosis in human T-lymphocytic and monocytic cell lines. In order to asses apoptosis, we used fluorescent microscopy to examine changes in light scattering as well as internucleosomal DNA fragmentation. Generation of a dose response curve showed that the minimum combination of UVA and 8-MOP that was necessary to induce greater than background levels of apoptosis within 24 h of treatment was 0.5 J/cm2 UVA and 12.5 ng/mL of 8-MOP. A striking observation was that UVA alone at doses > or = 1.0 J/cm2, but not 8-MOP alone (0-300 ng/mL), induced significant apoptosis in the Sup-T1 cells induced by UVA alone was not as great as that of 8-MOP and UVA in combination, a highly significant correlation between the product of the concentration of 8-MOP (ng/mL) times the dose of UVA (J/cm2) and the percentage of apoptotic cells was observed. This correlation provides an important tool for studying the relationship of UVA-induced DNA damage to apoptosis induction. moreover, it will provide a means by which early events in the apoptotic pathway can be dissected.