Gangliosides derived from a T cell lymphoma inhibit bone marrow cell proliferation and differentiation

Glutor, a Glucose Transporter Inhibitor, Exerts Antineoplastic Action on Tumor Cells of Thymic Origin: Implication of Modulated Metabolism, Survival, Oxidative Stress, Mitochondrial Membrane Potential, pH Homeostasis, and Chemosensitivity

Neoplastic cells overexpress glucose transporters (GLUT), particularly GLUT1 and GLUT3, to support altered metabolism. Hence, novel strategies are being explored to effectively inhibit GLUTs for a daunting interference of glucose uptake. Glutor, a piperazine-2-one derivative, is a newly reported pan-GLUT inhibitor with a promising antineoplastic potential. However, several aspects of the underlying mechanisms remain obscure. To understand this better, tumor cells of thymic origin designated as Dalton's lymphoma (DL) were treated with glutor and analyzed for survival and metabolism regulatory molecular events. Treatment of tumor cells with glutor caused a decrease in cell survival with augmented induction of apoptosis. It also caused a decrease in glucose uptake associated with altered expression of GLUT1 and GLUT3. HIF-1α, HK-2, LDH-A, and MCT1 also decreased with diminished lactate production and deregulated pH homeostasis. Moreover, glutor treatment modulated the expression of cell survival regulatory molecules p53, Hsp70, IL-2 receptor CD25, and C-myc along with mitochondrial membrane depolarization, increased intracellular ROS expression, and altered Bcl-2/BAX ratio. Glutor also enhanced the chemosensitivity of tumor cells to cisplatin, accompanied by decreased MDR1 expression. Adding fructose to the culture medium containing glutor reversed the latter's inhibitory action on tumor cell survival. These results demonstrate that in addition to inhibited glucose uptake, modulated tumor growth regulatory molecular pathways are also implicated in the manifestation of the antineoplastic action of glutor. Thus, the novel findings of this study will have a long-lasting clinical significance in evaluating and optimizing the use of glutor in anticancer therapeutic strategies.

Fat for fuel: lipid metabolism in haematopoiesis

The importance of metabolic regulation in the immune system has launched back into the limelight in recent years. Various metabolic pathways have been examined in the context of their contribution to maintaining immune cell homeostasis and function. Moreover, this regulation is also important in the immune cell precursors, where metabolism controls their maintenance and cell fate. This review will discuss lipid metabolism in the context of haematopoiesis, that is blood cell development. We specifically focus on nonoxidative lipid metabolism which encapsulates the synthesis and degradation of the major lipid classes such as phospholipids, sphingolipids and sterols. We will also discuss how these metabolic processes are affected by haematological malignancies such as leukaemia and lymphoma, which are known to have altered metabolism, and how these different pathways contribute to the pathology.

Challenges and future perspectives of T cell immunotherapy in cancer

Since the formulation of the tumour immunosurveillance theory, considerable focus has been on enhancing the effectiveness of host antitumour immunity, particularly with respect to T cells. A cancer evades or alters the host immune response by various ways to ensure its development and survival. These include modifications of the immune cell metabolism and T cell signalling. An inhibitory cytokine milieu in the tumour microenvironment also leads to immune suppression and tumour progression within a host. This review traces the development in the field and attempts to summarize the hurdles that the approach of adoptive T cell immunotherapy against cancer faces, and discusses the conditions that must be improved to allow effective eradication of cancer.

Myelopoietic efficacy of orlistat in murine hosts bearing T cell lymphoma: implication in macrophage differentiation and activation

Orlistat, an inhibitor of fatty acid synthase (FASN), acts as an antitumor agent by blocking de novo fatty acid synthesis of tumor cells. Although, myelopoiesis also depends on de novo fatty acid synthesis, the effect of orlistat on differentiation of macrophages, which play a central role in host’s antitumor defence, remains unexplored in a tumor-bearing host. Therefore, the present investigation was undertaken to examine the effect of orlistat administration on macrophage differentiation in a T cell lymphoma bearing host. Administration of orlistat (240 mg/kg/day/mice) to tumor-bearing mice resulted in a decline of tumor load accompanied by an augmentation of bone marrow cellularity and survival of bone marrow cells (BMC). The expression of apoptosis regulatory caspase-3, Bax and Bcl2 was modulated in the BMC of orlistat-administered tumor-bearing mice. Orlistat administration also resulted in an increase in serum level of IFN-γ along with decreased TGF-β and IL-10. BMC of orlistat-administered tumor-bearing mice showed augmented differentiation into macrophages accompanied by enhanced expression of macrophage colony stimulating factor (M-CSF) and its receptor (M-CSFR). The macrophages differentiated from BMC of orlistat-administered mice showed characteristic features of M₁ macrophage phenotype confirmed by expression of CD11c, TLR-2, generation of reactive oxygen species, phagocytosis, tumor cell cytotoxicity, production of IL-1,TNF-α and nitric oxide. These novel findings indicate that orlistat could be useful to support myelopoesis in a tumor-bearing host.

GD1a modulates GM-CSF-induced cell proliferation

Gangliosides have been extensively described to be involved in the proliferation and differentiation of various cell types, such including hematopoietic cells. Our previous studies on murine models of stroma-mediated myelopoiesis have shown that gangliosides are required for optimal capacity of stromal cells to support proliferation of myeloid precursor cells, being shed to the supernatant and selectively incorporated into myeloid cell membranes. Here we describe the effect of gangliosides on the specific granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced proliferation. For that, we used the monocytic FDC-P1 cell line, which is dependent upon GM-CSF for survival and proliferation. Cells were cultured in the presence of GM-CSF and exogenous gangliosides (GM3, GD1a or GM1) or in the absence of endogenous ganglioside synthesis by the use of a ceramide-synthase inhibitor, D-PDMP. We observed that exogenous addition of GD1a enhanced the GM-CSF-induced proliferation of the FDC-P1 cells. Also, we detected an increase in the expression of the α isoform of the GM-CSF receptor (GMRα) as well as of the transcription factor C/EBPα. On the contrary, inhibition of glucosylceramide synthesis was accompanied by a decrease in cell proliferation, which was restored upon the addition of exogenous GD1a. We also show a co-localization of GD1a and GMR by immunocytochemistry. Taken together, our results suggest for the first time that ganglioside GD1a play a role on the modulation of GM-CSF-mediated proliferative response, which might be of great interest not only in hematopoiesis, but also in other immunological processes, Alzheimer disease, alveolar proteinosis and wherever GM-CSF exerts its effects.

Anti-tumor immunity and mechanism of immunosuppression mediated by tumor cells: role of tumor-derived soluble factors and cytokines

The immune system plays a crucial role in the protection against tumor growth and progression. However, the activation of the immune system against the neoplastic cells does not always occur and, therefore, tumor cells are able to grow and progress continually in the host. It has now been realized that tumor cells themselves produce many of the important factors that are responsible for dismounting of effective immune response. These tumor-derived soluble factors invariably subdue the functions of almost every immune cell population. Therefore, we attempted to underline the mechanism of anti-tumor immune response and immunosuppression induced by tumor cells.

Anchored and soluble gangliosides contribute to myelosupportivity of stromal cells

Stroma-mediated myelopoiesis depends upon growth factors and an appropriate intercellular microenvironment. Previous studies have demonstrated that gangliosides, produced by hepatic stromal cell types, are required for optimal myelosupportive function. Here, we compared the mielossuportive functions of a bone marrow stroma (S17) and skin fibroblasts (SF) regarding their ganglioside pattern of synthesis and shedding. The survival and proliferation of a myeloid precursor cell (FDC-P1) were used as reporter. Although the ganglioside synthesis of the two stromal cells was similar, their relative content and shedding were distinct. The ganglioside requirement for mielossuportive function was confirmed by the decreased proliferation of FDC-P1 cells in ganglioside synthesis-inhibited cultures and in presence of an antibody to GM3 ganglioside. The distinct mielossuportive activities of the S17 and SF stromata may be related to differences on plasma membrane ganglioside concentrations or to differences on the gangliosides shed and their subsequent uptake by myeloid cells, specially, GM3 ganglioside.

Antitumor Activation of Peritoneal Macrophages by Thymosin Alpha-1

It was been previously reported that thyalpha1 can be used to activate monocytes, BMDM and TAM. However, the effect of thyalpha1 on other tissue macrophages has not been investigated. Moreover, there is no report about the use of thyalpha1-treated macrophages in adoptive immunotherapy of cancer. In view of these observations in the present study, we checked the response of various tissue macrophages to thyalpha1 for activation. Tissue macrophages showed differential response to thyalpha1; moreover, adoptive transfer of peritoneal macrophages treated with thyalpha1 to mice bearing spontaneous T-cell lymphoma designated as Dalton's lymphoma (DL) resulted in the prolongation of the survival time of tumor-bearing mice. The mechanism of macrophage therapy-dependent tumor regression was enhanced antitumor activity of macrophages in response to thyalpha1 treatment via their production of macrophage-activating cytokines that act in autocrine manner. These results will help in the development of immunotherapy against tumor based on activation of macrophage with thyalpha1.

Signaling defects in anti-tumor T cells

The immune response to cancer has been long recognized, including both innate and adaptive responses, showing that the immune system can recognize protein products of genetic and epigenetic changes in transformed cells. The accumulation of antigen-specific T cells within the tumor, the draining lymph node, and the circulation, either in newly diagnosed patients or resultant from experimental immunotherapy, proves that tumors produce antigens and that priming occurs. Unfortunately, just as obviously, tumors grow, implying that anti-tumor immune responses are either not sufficiently vigorous to eliminate the cancer or that anti-tumor immunity is suppressed. Both possibilities are supported by current data. In experimental animal models of cancer and also in patients, systemic immunity is usually not dramatically suppressed, because tumor-bearing animals and patients develop T-cell-dependent immune responses to microbes and to either model antigens or experimental cancer vaccines. However, inhibition of specific anti-tumor immunity is common, and several possible explanations of tolerance to tumor antigens or tumor-induced immunesuppression have been proposed. Inhibition of effective anti-tumor immunity results from the tumor or the host response to tumor growth, inhibiting the activation, differentiation, or function of anti-tumor immune cells. As a consequence, anti-tumor T cells cannot respond productively to developmental, targeting, or activation cues. While able to enhance the number and phenotype of anti-tumor T cells, the modest success of immunotherapy has shown the necessity to attempt to reverse tolerance in anti-tumor T cells, and the vanguard of experimental therapy now focuses on vaccination in combination with blockade of immunosuppressive mechanisms. This review discusses several potential mechanisms by which anti-tumor T cells may be inhibited in function.

Restoration of Thymic Homeostasis in a Tumor-Bearing Host by in Vivo Administration of Medicinal Herb Tinospora Cordifolia

In vivo administration of alcoholic extract of medicinal plant Tinospora cordifolia (TC) to mice bearing a spontaneous T cell lymphoma designated as Dalton's lymphoma prevented tumor growth-dependent regression of thymus. TC was found to augment proliferation of thymocytes with a concomitant decrease in thymocyte apoptosis. It also resulted in a decrease in the number of Hassal's corpuscles. Restoration of thymus homeostasis was caused by TC-dependent augmentation in production of thymocyte growth promoting cytokines Interleukin-2 and Interferon-gamma from thymocytes. TC was found to downregulate thymocyte apoptosis by modulation of Caspase pathway. TC administration retarded tumor growth and prolonged survival of tumor-bearing mice. The possible mechanisms are discussed.

Gender dimorphism in the myeloid differentiation of bone marrow precursor cells in a murine host bearing a T cell lymphoma

Little information is available regarding the existence of gender dimorphism of tumor growth for most types of tumors. In a previous report we have demonstrated the existence of gender dimorphism in the growth of a murine T cell lymphoma, designated as Dalton's lymphoma (DL); moreover, tumor-associated macrophages (TAM) were found to play a central role in the manifestation of gender dimorphism observed in the growth of this T cell lymphoma. In view of these observations, the present investigation was undertaken to study if gender dimorphism in the growth of a T cell tumor also could be associated with a gender-dependent differential myelopoiesis of bone marrow cells. We have demonstrated the existence of a gender dimorphism in the proliferation, apoptosis and myeloid differentiation of bone marrow cells obtained from male and female tumor-bearing hosts. Androgen and estrogen were found to alter directly the growth properties of bone marrow cells, as also determined by the use of receptor antagonists of these hormones, flutamide and tamoxifen. Bone marrow cells of male and female tumor-bearing hosts also showed a differential expression of the cell cycle and apoptosis regulatory protein p53 and macrophage-colony stimulating factor (M-CSF) genes. Bone marrow cells of male tumor-bearing hosts showed a predominant differentiation in the macrophage lineage whereas those of female tumor-bearing mice were in the granulocyte lineage. Bone marrow-derived macrophages (BMDM) from male and female tumor-bearing mice also showed the existence of gender dimorphism with respect to their differentiation and activation. These observations are of clinical significance with respect to understanding of the host-tumor relationship at the level of gender dimorphism of myelopoiesis.

Gangliosides of the stroma layer participate in the interferon-gamma receptor-dependent controls of myelopoiesis

Stroma-mediated myelopoiesis depends upon growth-factors and an appropriate intercellular microenvironment, whose polarity is relevant for granulocyte-macrophage colony stimulating factor (GM-CSF) mediated myeloid cell proliferation. Here we have studied qualitative and quantitative aspects of ganglioside participation in controls of the microenvironment required to sustain myelopoiesis. We analysed ganglioside synthesis, expression and shedding by two primary liver stromal cell cultures isolated from wild type and interferon-gamma (IFNgamma) receptor knockout mice. The latter one has a higher capacity to sustain myelopoiesis. FDC-P1 myeloid growth factor-dependent cell line was used as the reporter system, monitoring the cell survival and proliferation that reflect the bio-availability and the activity of GM-CSF. Although the two stromal cells synthesised the same gangliosides their relative content was quite different. FDC-P1 proliferation decreased in cultures in which ganglioside synthesis was inhibited in the stroma, as well as in presence of stroma cell supernatants in which GM3 was neutralised by the anti-GM3 monoclonal antibody. Addition of exogenous GM3 reverted the inhibition and sustained proliferation of FDC-P1 cells. FDC-P1 cells do not accumulate GM3, but they are able to take up the stroma-produced sphingolipids. Thus, stroma has a double role in sustaining myelopoiesis, providing both growth factor(s) and ganglioside(s) required for the optimal stimulation of the myeloid cell proliferation, and the IFNgamma mediated stroma-dependent controls of myelopoiesis are determinant for this cell interaction.

Effect of alcoholic extract of Ayurvedic herb Tinospora cordifolia on the proliferation and myeloid differentiation of bone marrow precursor cells in a tumor-bearing host

The present study investigates the effect of in vivo administration of alcoholic extract of Tinospora cordifolia whole plant (ALTC) on the proliferation and myeloid differentiation of bone marrow hematopoietic precursor cells in mice bearing a transplantable T cell lymphoma of spontaneous origin designated as Dalton's lymphoma (DL). BMC obtained from ALTC administered DL-bearing mice showed an enhanced BMC proliferation and colony forming ability in vitro in response to L929 conditioned medium as a source of colony stimulating factor (CSF). The number of granulocyte-macrophages colony (CFU-GM) was predominantly higher in the cultures of BMC obtained from ALTC administered mice as compared to mice injected with PBS alone. An increase in the count of bone marrow derived macrophages (BMDM) from ALTC administered mice was also observed along with an increase in the count of tumor associated macrophages. The BMDM obtained from ALTC administered mice showed an enhanced response to signal of LPS for activation to produce IL-1 and TNF. This study indicates that the T. cordifolia can influence the myeloid differentiation of bone marrow progenitor cells and the recruitment of macrophages in response to tumor growth in situ.

Effect of Tinospora cordifolia on the antitumor activity of tumor-associated macrophages-derived dendritic cells

We and others previously have reported that extract prepared from medicinal plant Tinospora cordifolia shows a wide spectrum of immunoaugmentary effects. Tinospora cordifolia was shown to upregulate antitumor activity of tumor-associated macrophages (TAM). In this article we present evidence to show that an alcoholic extract of Tinospora cordifolia (ALTC) enhances the differentiation of TAM to dendritic cells (DC) in response to granulocyte/macrophage-colony-stimulating factor, interleukin-4, and tumor necrosis factor. DC differentiated in vitro from TAM that were harvested from tumor-bearing mice after i.p. administration of ALTC (200 mg/kg body weight) 2 days posttumor transplantation shows an enhanced tumor cytotoxicity and production of tumoricidal soluble molecules like TNF, IL-1, and NO. Adoptive transfer of these TAM-derived DC to Dalton's lymphoma-bearing mice resulted in prolongation of survival of tumor-bearing mice. This is the first report regarding the differentiation and antitumor functions of TAM-derived DC obtained from tumor-bearing host administered with ALTC. The possible mechanisms involved also are discussed.

Milk-Derived GM3 and GD3 Differentially Inhibit Dendritic Cell Maturation and Effector Functionalities

Gangliosides are complex glycosphingolipids, which exert immune-modulating effects on various cell types. Ganglioside GD(3) and GM(3) are the predominant gangliosides of human breast milk but during the early phase of lactation, the content of GD(3) decreases while GM(3) increases. The biological value of gangliosides in breast milk has yet to be elucidated but when milk is ingested, dietary gangliosides might conceptually affect immune cells, such as dendritic cells (DCs). In this study, we address the in vitro effect of GD(3) and GM(3) on DC effector functionalities. Treatment of bone marrow-derived DCs with GD(3) before lipopolysaccharide-induced maturation decreased the production of interleukin-6 (IL-6), IL-10, IL-12 and tumor necrosis factor-alpha as well as reduced the alloreactivity in mixed leucocyte reaction (MLR). In contrast, only IL-10 and IL-12 productions were significantly inhibited by GM(3,) and the potency of DCs to activate CD4(+) cells in MLR was unaffected by GM(3). However, both gangliosides suppressed expression of CD40, CD80, CD86 and major histocompatibility complex class II on DCs. Because GD(3) overall inhibits DC functionalities more than GM(3), the immune modulating effect of the ganglioside fraction of breast milk might be more prominent in the commencement of lactation during which the milk contains the most GD(3).

Role of host's antitumor immunity in exercise-dependent regression of murine T-cell lymphoma

We have reported that the ascitic growth of a transplantable T cell lymphoma of spontaneous origin, designated as Dalton's lymphoma (DL), is associated with a concomitant immunosuppression. We have also reported that progressive in vivo growth of DL resulted in an inhibition of macrophage functions. In present investigation we report that physical exercise by DL-bearing mice, on a treadmill on a daily basis for various time durations for 10 days, increased the life span along with an inhibition of tumor growth. A significant decrease in the volume of ascitic fluid and number of cells in the tumor was obtained in mice, which underwent exercise. DL cells obtained from exercised groups showed a decreased proliferation in vitro. An augmentation in the percent of cells showing apoptotic morphology and percent specific DNA fragmentation was observed, suggesting that physical exercise increased the incidence of apoptosis in tumor cells. Moreover, macrophages obtained from tumor-bearing mice, which underwent exercise training, showed an augmented tumoricidal activity and production of tumoricidal molecules like interleukin-1 (IL-1), tumor necrosis factor (TNF) and nitric oxide (NO). On the basis of this study it is suggested that the regression of tumor growth consequent to physical exercise training of tumor bearing host, may be due to an exercise-dependent augmentation of macrophage tumoricidal functions.

Gender dimorphism in the progressive in vivo growth of a T cell lymphoma: involvement of cytokines and gonadal hormones

The present investigation was carried out to investigate gender dimorphism with respect to the progressive in vivo growth a of T cell lymphoma in a murine system. It was observed that in vivo progression of a transplantable T cell lymphoma of spontaneous origin, designated as Dalton's lymphoma (DL), shows differential growth kinetics in male and female mice. DL growth was observed to be faster in female mice as compared to male mice. We demonstrate the involvement of gender specific gonadal hormones, tumor-associated macrophage (TAM)-derived IL-1 and differential level of IL-4, IL-10 and TNF-alpha in the ascitic fluid of DL-bearing male and female mice. The study has a clinical significance, as the results will help in understanding the mechanism of gender dimorphism with respect to the progression of T cell tumors and in the designing of immunotherapy for such tumors.