Cell Survival Regulatory Molecules Research Articles

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.

Antitumor action of 3-bromopyruvate implicates reorganized tumor growth regulatory components of tumor milieu, cell cycle arrest and induction of mitochondria-dependent tumor cell death

Evidences demonstrate that metabolic inhibitor 3-bromopyruvate (3-BP) exerts a potent antitumor action against a wide range of malignancies. However, the effect of 3-BP on progression of the tumors of thymic origin remains unexplored. Although, constituents of tumor microenvironment (TME) plays a pivotal role in regulation of tumor progression, it remains unclear if 3-BP can alter the composition of the crucial tumor growth regulatory components of the external surrounding of tumor cells. Thus, the present investigation attempts to understand the effect of 3-BP administration to a host bearing a progressively growing tumor of thymic origin on tumor growth regulatory soluble, cellular and biophysical components of tumor milieu vis-à-vis understanding its association with tumor progression, accompanying cell cycle events and mode of cell death. Further, the expression of cell survival regulatory molecules and hemodynamic characteristics of the tumor milieu were analysed to decipher mechanisms underlying the antitumor action of 3-BP. Administration of 3-BP to tumor-bearing hosts retarded tumor progression accompanied by induction of tumor cell death, cell cycle arrest, declined metabolism, inhibited mitochondrial membrane potential, elevated release of cytochrome c and altered hemodynamics. Moreover, 3-BP reconstituted the external milieu, in concurrence with deregulated glucose and pH homeostasis and increased tumor infiltration by NK cells, macrophages, and T lymphocytes. Further, 3-BP administration altered the expression of key regulatory molecules involved in glucose uptake, intracellular pH and tumor cell survival. The outcomes of this study will help in optimizing the therapeutic application of 3-BP by targeting crucial tumor growth regulatory components of tumor milieu.

Antitumor and chemosensitizing action of 3-bromopyruvate: Implication of deregulated metabolism

3-Bromopyruvate (3-BP), brominated derivative of pyruvate, possesses strong antitumor potential, owing to its ability to inhibit multiple target molecules crucial for survival of neoplastic cells. Although, 3-BP displays cytotoxicity against a wide variety of tumors, there is no report with respect to malignancies of thymic origin. Therefore, we investigated its antineoplastic action in vitro against tumor cells of a murine transplantable lymphoma of thymoma origin, designated as Dalton's lymphoma (DL). 3-BP treatment of tumor cells inhibited metabolism and survival with augmented induction of apoptosis and necrosis. 3-BP treatment suppressed lactate release, glucose uptake, deregulated pH homeostasis and augmented chemosensitization. It also altered expression of metabolism, chemosensitivity and cell survival regulatory molecules including HK 2, GAPDH, LDH, SDH, HIF-1α, MDR-1 & GLUT-1 and cytokine repertoire of IFN-γ, IL-6, IL-10, & VEGF. Pretreatment with MCT-1 inhibitor α-cyano-4-hydroxycinnamate and siRNA gene silencing of HK 2 implicated the role of MCT-1 and HK 2 in 3-BP cytotoxicity. 3-BP also altered expression of cell death regulatory Bcl-2, Mcl-1, caspase-3 accompanied by increased cytochrome c release, indicating mitochondrial mode of cell death. The study collates possible molecular mechanisms of cytotoxic action of 3-BP, which will help to optimize the therapeutic efficacy of 3-BP against tumors of thymic origin.

Antitumor and chemosensitizing action of dichloroacetate implicates modulation of tumor microenvironment: A role of reorganized glucose metabolism, cell survival regulation and macrophage differentiation

Targeting of tumor metabolism is emerging as a novel therapeutic strategy against cancer. Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), has been shown to exert a potent tumoricidal action against a variety of tumor cells. The main mode of its antineoplastic action implicates a shift of glycolysis to oxidative metabolism of glucose, leading to generation of cytotoxic reactive oxygen intermediates. However, the effect of DCA on tumor microenvironment, which in turn regulates tumor cell survival; remains speculative to a large extent. It is also unclear if DCA can exert any modulatory effect on the process of hematopoiesis, which is in a compromised state in tumor-bearing hosts undergoing chemotherapy. In view of these lacunas, the present study was undertaken to investigate the so far unexplored aspects with respect to the molecular mechanisms of DCA-dependent tumor growth retardation and chemosensitization. BALB/c mice were transplanted with Dalton's lymphoma (DL) cells, a T cell lymphoma of spontaneous origin, followed by administration of DCA with or without cisplatin. DCA-dependent tumor regression and chemosensitization to cisplatin was found to be associated with altered repertoire of key cell survival regulatory molecules, modulated glucose metabolism, accompanying reconstituted tumor microenvironment with respect to pH homeostasis, cytokine balance and alternatively activated TAM. Moreover, DCA administration also led to an alteration in the MDR phenotype of tumor cells and myelopoietic differentiation of macrophages. The findings of this study shed a new light with respect to some of the novel mechanisms underlying the antitumor action of DCA and thus may have immense clinical applications.

Targeting monocarboxylate transporter by α-cyano-4-hydroxycinnamate modulates apoptosis and cisplatin resistance of Colo205 cells: implication of altered cell survival regulation

The present investigation was undertaken to study the effect of in vitro exposure of Colo205, colonadenocarcinoma cells, to monocarboxylate transporter inhibitor α-cyano-4-hydroxycinnamate (αCHC) on cell survival and evolution of resistance to chemotherapeutic drug cisplatin. αCHC-treated Colo205 cells showed inhibition of survival accompanied by an augmented induction of apoptosis. Changes in cell survival properties were associated with alterations in lactate efflux, pH homeostasis, expression of glucose transporters, glucose uptake, HIF-1α, generation of nitric oxide, expression pattern of some key cell survival regulatory molecules: Bcl2, Bax, active caspase-3 and p53. Pretreatment of Colo205 cells with αCHC also altered their susceptibility to the cytotoxicity of cisplatin accompanied by altered expression of multidrug resistance regulating MDR1 and MRP1 genes. This study for the first time deciphers some of the key molecular events underlying modulation of cell survival of cancer cells of colorectal origin by αCHC and its contribution to chemosensitization against cisplatin. Thus these findings will be of immense help in further research for optimizing the use of αCHC for improving the chemotherapeutic efficacy of anticancer drugs like cisplatin.

Fatty acid synthase inhibitor orlistat induces apoptosis in T cell lymphoma: Role of cell survival regulatory molecules

BackgroundDe 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. MethodsThe 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. ResultsWe 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. Conclusion and general significanceIn 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.

Myelopotentiating effect of curcumin in tumor-bearing host: Role of bone marrow resident macrophages

The present investigation was undertaken to study if curcumin, which is recognized for its potential as an antineoplastic and immunopotentiating agent, can also influence the process of myelopoiesis in a tumor-bearing host. Administration of curcumin to tumor-bearing host augmented count of bone marrow cell (BMC) accompanied by an up-regulated BMC survival and a declined induction of apoptosis. Curcumin administration modulated expression of cell survival regulatory molecules: Bcl2, p53, caspase-activated DNase (CAD) and p53-upregulated modulator of apoptosis (PUMA) along with enhanced expression of genes of receptors for M-CSF and GM-CSF in BMC. The BMC harvested from curcumin-administered hosts showed an up-regulated colony forming ability with predominant differentiation into bone marrow-derived macrophages (BMDM), responsive for activation to tumoricidal state. The number of F4/80 positive bone marrow resident macrophages (BMM), showing an augmented expression of M-CSF, was also augmented in the bone marrow of curcumin-administered host. In vitro reconstitution experiments indicated that only BMM of curcumin-administered hosts, but not in vitro curcumin-exposed BMM, augmented BMC survival. It suggests that curcumin-dependent modulation of BMM is of indirect nature. Such prosurvival action of curcumin is associated with altered TH1/TH2 cytokine balance in serum. Augmented level of serum-borne IFN-γ was found to mediate modulation of BMM to produce enhanced amount of monokines (IL-1, IL-6, TNF-α), which are suggested to augment the BMC survival. Taken together the present investigation indicates that curcumin can potentiate myelopoiesis in a tumor-bearing host, which may have implications in its therapeutic utility.

Novel molecular mechanisms of antitumor action of dichloroacetate against T cell lymphoma: Implication of altered glucose metabolism, pH homeostasis and cell survival regulation

Pyruvate dehydrogenase kinase (PDK) inhibits pyruvate dehydrogenase (PDH) activity and thus promotes energetic switch from mitochondrial glucose oxidation to cytoplasmic glycolysis in cancerous cells (a phenomenon known as the ‘Warburg effect’) for their energy need, which facilitates the cancer progression by resisting induction of apoptosis and promoting tumor metastasis. Thus, in the present investigation, we explored the molecular mechanisms of the tumoricidal action of dichloroacetate (DCA), a pyruvate dehydrogenase kinase inhibitor, on cells of a murine T cell lymphoma, designated as Dalton’s lymphoma (DL). In vitro treatment of tumor cells with DCA inhibited their survival accompanied by a modulation of the biophysical composition of tumor-conditioned medium with respect to pH, glucose and lactate. DCA treatment also altered expression of HIF1-α and pH regulators: VATPase and MCT1 and production of cytokines: IL-10, IL-6 and IFN-γ. Moreover, we also observed an alteration in the expression of other apoptosis and cell survival regulatory molecules: PUMA, GLUT1, Bcl2, p53, CAD, caspase-3 and HSP70. The study discusses the role of novel molecular mechanisms underlying DCA-dependent inhibition of tumor cell survival. This study shows for the first time that DCA-dependent alteration of tumor cell survival involves altered pH homeostasis and glucose metabolism. Thus, these findings will provide a new insight for therapeutic applications of DCA as a novel antineoplastic agent against T cell lymphoma.

Hyperglycemia of tumor microenvironment modulates stage‐dependent tumor progression and multidrug resistance: implication of cell survival regulatory molecules and altered glucose transport

Using a murine tumor model, we demonstrate that tumor cells display a tumor stage-dependent differential glucose utilization associated with an altered GLUT-1 expression. Hyperglycemic tumor microenvironment modulates the tumorigenic ability, survival, apoptosis, and glucose utilization of tumor cells in late tumor-bearing stage accompanied by an altered tumor acidosis and expression of cell survival regulatory molecules: HIF-1α, p53, Bcl2, caspase-activated DNase, IL-4, IL-6, IL-10, IFN-γ, TGF-β, and VEGF. Glucose-exposed tumor cells of late tumor-bearing stage also show a declined susceptibility to the cytotoxic action of chemotherapeutic drugs: cisplatin and methotrexate, accompanied by an increased expression of MDR-1 gene. Taken together the results show that hyperglycemic tumor microenvironment differentially alters tumor growth depending on the stage of tumor progression.

Gender-specific antitumor action of aspirin in a murine model of a T-cell lymphoma bearing host

Aspirin is an anti-inflammatory drug demonstrated to possess a tremendous anticancer potential. As progression of some tumors is influenced by sex hormones, we investigated if the antineoplastic action of aspirin shows gender dependence. Using a murine model of T-cell lymphoma, the present investigation was undertaken to study if the antitumor actions of aspirin against lymphoma cells display gender dimorphism. The findings of the present investigation indicate that aspirin administration to male and female tumor-bearing hosts resulted in gender dependent differential tumor growth retardation. Such gender dichotomy of aspirin's antitumor action was associated with a differential impact on cell cycle progression and expression of cell survival regulatory molecules. Aspirin administration was also found to modulate crucial parameters of tumor microenvironment, including contents of glucose, lactate and cell growth regulatory cytokines, in a gender specific manner. Aspirin was found to reverse estrogen-dependent augmentation of tumor cell survival in vitro. Taken together the results of the present study suggest that the antineoplastic action of aspirin is gender-dependent and should be considered in designing of gender-specific therapeutic applications of aspirin.

Anti-neoplastic action of aspirin against a T-cell lymphoma involves an alteration in the tumour microenvironment and regulation of tumour cell survival

The present study explores the potential of the anti-neoplastic action of aspirin in a transplantable murine tumour model of a spontaneously originated T-cell lymphoma designated as Dalton's lymphoma. The antitumour action of aspirin administered to tumour-bearing mice through oral and/or intraperitoneal (intratumoral) routes was measured via estimation of survival of tumour-bearing mice, tumour cell viability, tumour progression and changes in the tumour microenvironment. Intratumour administration of aspirin examined to assess its therapeutic potential resulted in retardation of tumour progression in tumour-bearing mice. Oral administration of aspirin to mice as a prophylactic measure prior to tumour transplantation further primed the anti-neoplastic action of aspirin administered at the tumour site. The anti-neoplastic action of aspirin was associated with a decline in tumour cell survival, augmented induction of apoptosis and nuclear shrinkage. Tumour cells of aspirin-treated mice were found arrested in G0/G1 phase of the cell cycle and showed nuclear localization of cyclin B1. Intratumoral administration of aspirin was accompanied by alterations in the biophysical, biochemical and immunological composition of the tumour microenvironment with respect to pH, level of dissolved O2, glucose, lactate, nitric oxide, IFNγ (interferon γ), IL-4 (interleukin-4), IL-6 and IL-10, whereas the TGF-β (tumour growth factor-β) level was unaltered. Tumour cells obtained from aspirin-treated tumour-bearing mice demonstrated an altered expression of pH regulators monocarboxylate transporter-1 and V-ATPase along with alteration in the level of cell survival regulatory molecules such as survivin, vascular endothelial growth factor, heat-shock protein 70, glucose transporter-1, SOCS-5 (suppressor of cytokine signalling-5), HIF-1α (hypoxia-inducible factor-1α) and PUMA (p53 up-regulated modulator of apoptosis). The study demonstrates a possible indirect involvement of the tumour microenvironment in addition to a direct but limited anti-neoplastic action of aspirin in the retardation of tumour growth.

Augmentation of myelopoiesis in a murine host bearing a T cell lymphoma following in vivo administration of proton pump inhibitor pantoprazole

Proton pump inhibitors (PPI) are being proposed as potent antitumor agents, owing to their ability to specifically induce tumor cell death by reversing H+ ion homeostasis. As tumor growth induces myelosuppression in tumor-bearing hosts, it remains unclear if PPI can also modulate tumor-induced myelosuppression. Thus, we studied the effect of in vivo administration of pantoprazole (PPZ), a PPI, on myelopoiesis in a murine model of a transplantable T cell lymphoma, designated as Dalton’s lymphoma (DL). Intraperitoneal administration of PPZ to tumor-bearing mice resulted in an enhanced bone marrow cellularity, inhibited induction of apoptosis and augmented bone marrow cell (BMC) survival. BMC of PPZ-administered tumor-bearing mice showed elevated number of F4/80 positive cells, augmented colony forming ability and differentiation in bone marrow-derived macrophages (BMDM) with higher expression of F4/80 and CD11c markers. This study also presents evidences to indicate that PPZ-dependent augmentation of myelopoiesis in the tumor-bearing host is dependent on an enhanced expression of M-CSF and receptors for M-CSF & GM-CSF in BMC, along with a modulation in the expression of cell survival regulatory molecules PUMA, Bcl2, p53 and caspase-activated DNase (CAD). BMDM obtained from PPZ-administered tumor-bearing mice also showed an augmented expression of TLR-2, tumoricidal activity, production of NO and monokines: IL-1, IL-6 & TNF-α. The study discusses the possible mechanisms underlying PPZ-dependent augmentation of myelopoiesis. Taken together, the present study proposes that a PPZ-dependent alleviation of tumor-induced myelosuppression could contribute to an augmented myelopoiesis.

31. The AGECAT computerised diagnostic system

3-Bromopyruvate (3-BP), brominated derivative of pyruvate, possesses strong antitumor potential, owing to its ability to inhibit multiple target molecules crucial for survival of neoplastic cells. Although, 3-BP displays cytotoxicity against a wide variety of tumors, there is no report with respect to malignancies of thymic origin. Therefore, we investigated its antineoplastic action in vitro against tumor cells of a murine transplantable lymphoma of thymoma origin, designated as Dalton's lymphoma (DL). 3-BP treatment of tumor cells inhibited metabolism and survival with augmented induction of apoptosis and necrosis. 3-BP treatment suppressed lactate release, glucose uptake, deregulated pH homeostasis and augmented chemosensitization. It also altered expression of metabolism, chemosensitivity and cell survival regulatory molecules including HK 2, GAPDH, LDH, SDH, HIF-1α, MDR-1 & GLUT-1 and cytokine repertoire of IFN-γ, IL-6, IL-10, & VEGF. Pretreatment with MCT-1 inhibitor α-cyano-4-hydroxycinnamate and siRNA gene silencing of HK 2 implicated the role of MCT-1 and HK 2 in 3-BP cytotoxicity. 3-BP also altered expression of cell death regulatory Bcl-2, Mcl-1, caspase-3 accompanied by increased cytochrome c release, indicating mitochondrial mode of cell death. The study collates possible molecular mechanisms of cytotoxic action of 3-BP, which will help to optimize the therapeutic efficacy of 3-BP against tumors of thymic origin.