orlistat and Lymphoma--T-Cell

Orlistat, a fatty acid synthase (FASN) inhibitor, has been demonstrated to inhibit tumor cell survival. However, the mechanism(s) of its tumor growth retarding action against malignancies of hematological origin remains unclear. It is also not understood if the antitumor action of orlistat implicates modulated susceptibility of tumor cell to anticancer drugs. Therefore, the present investigation focuses to study the antitumor and chemosensitizing action of orlistat in a murine host bearing a progressively growing T cell lymphoma.. Tumor-bearing mice were administered with vehicle alone or containing orlistat followed by administration of PBS with or without cisplatin. Tumor progression and survival of tumor-bearing host were monitored along with analysis of tumor cell survival and apoptosis. Tumor ascitic fluid was examined for pH, NO and cytokines. Expression of genes and proteins was investigated by RT-PCR and western blot respectively. ROS was analyzed by DCFDA staining and FASN activity by spectrophotometry.. Orlistat administration to tumor-bearing mice resulted in tumor growth retardation, prolonged life span, declined tumor cell survival and chemosensitization to cisplatin. It was accompanied by increased osmotic fragility, modulated acidosis, expression of ROS, NO, cytokines, MCT-1 and VH(+) ATPase, Bcl2, Caspase-3, P53, inhibited FASN activity and declined expression of MDR and MRP-1 proteins.. Orlistat manifests antitumor and chemosensitizing action implicating modulated regulation of cell survival, reconstituted-tumor microenvironment and altered MDR phenotype.. These observations indicate that orlistat could be utilized as an adjunct regimen for improving antitumor efficacy of cisplatin.

Topics: Animals; Anti-Obesity Agents; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Proliferation; Cisplatin; Disease Models, Animal; Drug Resistance, Multiple; Drug Therapy, Combination; Enzyme-Linked Immunosorbent Assay; Fatty Acid Synthases; Flow Cytometry; Lactones; Lymphoma, T-Cell; Mice; Mice, Inbred BALB C; Nitric Oxide Synthase Type II; Nitrites; Orlistat; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tumor Microenvironment

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.

Topics: Animals; Apoptosis; Bone Marrow Cells; Cell Count; Cell Differentiation; Cell Survival; Lactones; Lymphoma, T-Cell; Macrophage Activation; Macrophage Colony-Stimulating Factor; Macrophages; Mice; Mice, Inbred BALB C; Myelopoiesis; Orlistat; Phenotype; Receptor, Macrophage Colony-Stimulating Factor

De novo fatty acid synthesis catalyzed by fatty acid synthase (FASN) is crucial for tumor cell survival. Thus therapeutic targeting of FASN is considered as a novel antineoplastic strategy. However, little is understood in this respect regarding malignancies of hematological origin. The present investigation was therefore, undertaken to study the molecular mechanisms of the antitumor action of FASN inhibitor orlistat (tetrahydrolipstatin) using a murine model of a T cell lymphoma.. The antitumor efficacy of orlistat was investigated in vitro by estimating cell survival by MTT assay and apoptosis by Wright Giemsa, TUNEL, Annexin-V/PI staining and % DNA fragmentation. Generation of reactive oxygen species (ROS) in tumor cells was studied using fluorescence microscopy. Expression of genes and proteins was carried out by RT-PCR and western blot analyses respectively. FASN and CPT-1 activity was estimated by spectrophotometer. Cytokines expression was analyzed by ELISA.. We report that inhibition of FASN with its specific inhibitor orlistat manifests tumor-specific inhibition of cell survival, accompanied by induction of apoptosis. Orlistat-treated tumor cells showed an altered ROS generation, shift in cytokine balance and modulated expression of cell survival regulatory molecules like HSP70, Bcl2, p53, PUMA, Caspase-3 and CAD. It was observed that IFN-γ mediates orlistat-dependent modulation of FASN expression.. In this study, we report some of the so far unexplored novel aspects underlying the molecular mechanisms associated with orlistat-dependent modulation of tumor cell survival. These observations will help in designing antineoplastic therapeutic protocols using orlistat against malignancies of hematological origin.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Survival; Cytokines; Dose-Response Relationship, Drug; Fatty Acid Synthases; HSP70 Heat-Shock Proteins; Interferon-gamma; Lactones; Lymphoma, T-Cell; Male; Mice; Mice, Inbred BALB C; Orlistat; Reactive Oxygen Species