Metabolism Of Malignant Cells Research Articles

Abstract 1005: Mitochondrial inhibition decreases the malignant phenotype of esophageal adenocarcinoma cells through the induction of autophagy

Abstract OBJECTIVE Esophageal adenocarcinoma (EAC) is a lethal disease for which novel therapies are needed. Malignant cell metabolism often shifts from mitochondrial respiration to aerobic glycolysis (Warburg effect). However, glucose alone does not meet the metabolic requirements of cancer cells; therefore, glutamine becomes an essential nutrient. A critical step in glutamine metabolism is the conversion of glutamine to glutamate by the enzyme glutaminase-1 (Gls-1), a potential therapeutic target. The present study was undertaken to identify the effect of targeting glutamine utilization by the mitochondrion in EAC. METHODS Assays were performed in 3 EAC and 1 Barrett's cell lines: Flo-1, NCI-SB-ESC2 (Esc2), OE33, and CP-C. qRT-PCR and immunoblot were used for Gls-1 expression. Cyquant® and Millipore Invasion Kit measured proliferation and invasion. Flow cytometry, SA-β-galactosidase assay, and immunoblot assessed cell cycle, apoptosis, senescence, and autophagy. Seahorse Extracellular Flux Analyzer was used to quantitate mitochondrial respiration and glycolytic capacity. Cells were treated with bis-2 [5-phenylacetamido-1,2,4-thiadiazol-2-yl] ethylsulfide (BPTES), an inhibitor of Gls-1, and/or metformin, a mitochondrial electron transport chain inhibitor. Glycolysis was inhibited with 2-deoxyglucose (2-DG). Flo-1 and Esc2 were transduced with shRNA targeting Gls-1. RESULTS Glutamine withdrawal decreased proliferation of Flo-1, OE33, and CP-C more than Esc2. Similarly, BPTES caused a more significant decrease in proliferation in Flo-1, OE33, and CP-C than in Esc2. BPTES growth inhibition was reversed by α-ketoglutarate, a metabolite of glutamate. Unlike BPTES, metformin decreased proliferation in all cell lines which was augmented with 2-DG inhibition of glycolysis. Metabolic and knockdown experiments were performed in Flo-1 and Esc2. Glucose partially blocked mitochondrial spare capacity in Flo-1, but completely abrogated the spare capacity in Esc2 suggesting a higher glycolytic dependency in Esc2. Also, knockdown of Gls-1 blocked mitochondrial spare capacity and increased glycolysis in both cell lines. Knockdown of gls-1 decreased proliferation and invasion. Glutamine withdrawal induced autophagy as evidenced by increased LC3 and pAMPK and decreased p70 S6 Kinase in both cell lines. Apoptosis and senescence were not observed. To test glutamine's effect on glycolysis, glutamine repressed the negative regulator of glycolysis, thioredoxin interacting protein (TXNIP), suggesting that glutamine can increase glycolysis while simultaneously fueling the mitochrondria. CONCLUSIONS Mitochondrial respiration is mediated by both glucose and glutamine in EAC cells. Glutamine exerts an effect on glycolysis through repression of TXNIP. Whereas EAC cells have unique metabolic profiles, targeting common metabolic steps such as Gls-1 may be novel strategies to treat EAC. Citation Format: Deborah R. Depew, Paul L. Feingold, Kate Brown, Yuan Xu, Mahadev Rao, Michael Moses, Leonard M. Neckers, David S. Schrump, R Taylor Ripley. Mitochondrial inhibition decreases the malignant phenotype of esophageal adenocarcinoma cells through the induction of autophagy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1005.

N-Glycolyl GM3 Ganglioside as a Relevant Tumor Antigen in Humans

It is known, human cells are incapable of synthesizing the N-glycolyl neuraminic acid (NeuGc) due to the inactivation of the cytidine monophospho-N-acetyl-neuraminic acid hydroxylase, the enzyme responsible for the synthesis of this sialic acid. Conversely, the aberrant expression of NeuGc-sialoconjugates has been detected in humans, although preferentially in malignant tissues. The more accepted hypothesis for the presence of NeuGc in human malignancies is associated with its incorporation from dietary sources to the altered metabolism of malignant cells which is also favored by the hypoxic conditions of tumors. However, the significance of NeuGccontaining conjugates in tumor biology as well as its clinical implications is still under investigation. One of these molecules is Nglycolyl GM3 ganglioside (NeuGcGM3).

Homocysteine Metabolism, Atherosclerosis, and Diseases of Aging.

The importance of homocysteine in vascular function and arteriosclerosis was discovered by demonstration of arteriosclerotic plaques in children with homocystinuria caused by inherited enzymatic deficiencies of cystathionine synthase, methionine synthase, or methylene-tetrahydrofolate reductase. According to the homocysteine theory of arteriosclerosis, an elevated blood homocysteine level is an important risk factor for atherosclerosis in subjects without these rare enzymatic abnormalities. The homocysteine theory is supported by demonstration of arterial plaques in experimental animals with hyperhomocysteinemia, by discovery of a pathway for conversion of homocysteine thiolactone to sulfate in cell cultures from children with homocystinuria, and by demonstration of growth promotion by homocysteic acid in normal and hypophysectomized animals. Studies with cultured malignant cells revealed abnormal homocysteine thiolactone metabolism, resulting in homocysteinylation of proteins, nucleic acids, and glycosaminoglycans, explaining the abnormal oxidative metabolism, abnormalities of cellular membranes, and altered genetic expression observed in malignancy. Abnormal homocysteine metabolism in malignant cells is attributed to deficiency of thioretinamide, the amide synthesized from retinoic acid and homocysteine thiolactone. Two molecules of thioretinamide combine with cobalamin to form thioretinaco. Based on the molecular structure of thioretinaco, a theory of oxidative phosphorylation was proposed, involving oxidation to a disulfonium derivative by ozone, and binding of oxygen, nicotinamide adenine dinucleotide and phosphate as the active site of adenosine triphosphate synthesis in mitochondria. Obstruction of vasa vasorum by aggregates of microorganisms with homocysteinylated low-density lipoproteins is proposed to cause ischemia of arterial wall and a microabscess of the intima, the vulnerable atherosclerotic plaque.

ATPS-96HISTONE DEACETYLASE INHIBITORS REPRESS HYPOXIA SIGNALING THROUGH AFFECTING HSP90

Histone deacetylase inhibitors (HDACis) are among the most promising recently developed anti-cancer agents. Recent work suggests that HDACis suppress both malignant cell metabolism and progression by interfering with the hypoxia-inducible factor (HIF) signaling, which plays a key role in tumor progression in both actual and falsely perceived cellular hypoxia (pseudohypoxia). However, the precise biochemical mechanism of HDACis repression of HIFs function remains unclear. In this study, we demonstrated that the class-2 histone deacetylase inhibitor SAHA potently inhibits hypoxia signaling via interfering with heat shock protein 90 (Hsp90). HDACis increase in the acetylation of Hsp90, resulting in less HIF-a recognition and nuclear translocation. Accumulated cytoplasmic HIF-a is not transcriptional active and degradaded through proteosomal pathway. Finally, we demonstrated that SAHA remarkably reduce hypoxia signaling and decrease tumor growth in vivo. These findings provide insight into new possible therapeutic strategies for using HDACis in tumors with known HIF pathway aberrations.

When Anti-Aging Studies Meet Cancer Chemoprevention: Can Anti-Aging Agent Kill Two Birds with One Blow?

Recent evidence has strongly supported that the rate of aging is controlled, at least to some extent, by evolutionarily conserved nutrient sensing pathways (e.g. the insulin/IGF-1-signaling, mTOR, AMPK, and sirtuins) from worms to humans. These pathways are also commonly involved in carcinogenesis and cancer metabolism. Agents (e.g. metformin, resveratrol, and Rhodiola) that target these nutrient sensing pathways often have both anti-aging and anti-cancer efficacy. These agents not only reprogram energy metabolism of malignant cells, but also target normal postmitotic cells by suppressing their conversion into senescent cells, which confers systematic metabolism benefits. These agents are fundamentally different from chemotherapy (e.g. paclitaxel and doxorubicin) or radiation therapy that causes molecular damage (e.g. DNA and protein damages) and thereby no selection resistance may be expected. By reviewing molecular mechanisms of action, epidemiological evidence, experimental data in tumor models, and early clinical study results, this review provides information supporting the promising use of agents with both anti-aging and anti-cancer efficacy for cancer chemoprevention.

Adipose tissue dysfunction and its effects on tumor metabolism.

Growing by an alarming rate in the Western world, obesity has become a condition associated with a multitude of diseases such as diabetes, metabolic syndrome and various cancers. Generally viewed as an abnormal accumulation of hypertrophied adipocytes, obesity is also a poor prognostic factor for recurrence and chemoresistance in cancer patients. With more than two-thirds of the adult population in the United States considered clinically overweight or obese, it is critical that the relationship between obesity and cancer is further emphasized and elucidated. Adipocytes are highly metabolically active cells, which, through release of adipokines and cytokines and activation of endocrine and paracrine pathways, affect processes in neighboring and distant cells, altering their normal homeostasis. This work will examine specifically how adipocyte-derived factors regulate the cellular metabolism of malignant cells within the tumor niche. Briefly, tumor cells undergo metabolic pressure towards a more glycolytic and hypoxic state through a variety of metabolic regulators and signaling pathways, i.e., phosphoinositol-3 kinase (PI3K), hypoxia-inducible factor-1 alpha (HIF-1α), and c-MYC signaling. Enhanced glycolysis and high lactate production are hallmarks of tumor progression largely because of a process known as the Warburg effect. Herein, we review the latest literature pertaining to the body of work on the interactions between adipose and tumor cells, and underlining the changes in cancer cell metabolism that have been targeted by the currently available treatments.

Regulatory effects of a Mnk2-eIF4E feedback loop during mTORC1 targeting of human medulloblastoma cells.

The mTOR pathway controls mRNA translation of mitogenic proteins and is a central regulator of metabolism in malignant cells. Development of malignant cell resistance is a limiting factor to the effects of mTOR inhibitors, but the mechanisms accounting for such resistance are not well understood. We provide evidence that mTORC1 inhibition by rapamycin results in engagement of a negative feedback regulatory loop in malignant medulloblastoma cells, involving phosphorylation of the eukaryotic translation-initiation factor eIF4E. This eIF4E phosphorylation is Mnk2- mediated, but Mnk1-independent, and acts as a survival mechanism for medulloblastoma cells. Pharmacological targeting of Mnk1/2 or siRNA-mediated knockdown of Mnk2 sensitizes medulloblastoma cells to mTOR inhibition and promotes suppression of malignant cell proliferation and anchorage-independent growth. Altogether, these findings provide evidence for the existence of a Mnk2-controlled feedback loop in medulloblastoma cells that accounts for resistance to mTOR inhibitors, and raise the potential for combination treatments of mTOR and Mnk inhibitors for the treatment of medulloblastoma.

Chapter Two - Autophagy and Cancer Metabolism

The metabolism of malignant cells is profoundly altered in order to maintain their survival and proliferation in adverse microenvironmental conditions. Autophagy is an intracellular recycling process that maintains basal levels of metabolites and biosynthetic intermediates under starvation or other forms of stress, hence serving as an important mechanism for metabolic adaptation in cancer cells. Although it is widely acknowledged that autophagy sustains metabolism in neoplastic cells under duress, many questions remain with regard to the mutual relationship between autophagy and metabolism in cancer. Importantly, autophagy has often been described as a "double-edged sword" that can either impede or promote cancer initiation and progression. Here, we overview such a dual function of autophagy in tumorigenesis and our current understanding of the coordinated regulation of autophagy and cancer cell metabolism in the control of tumor growth, progression, and resistance to therapy.

Meme kanserli bir hastada 18-Floro-de-oksi-Glukoz pozitron emisyon tomografisinde multiple kemik metastazları: Olgu sunumu ve literatürün gözden geçirilmesi [Multiple bone metastases detected on 2-[18F]-fluoro-2-deoxy-d-glucose PET

Bone scintigraphy has been widely used to assess skeletal metastasis in patients with breast cancer. 18F-FDG-PET/CT is another imaging modality that has gained previously wide use to determine metastasis based on increased glucose metabolism in malignant cells. Generally, these two modalities give similar results in evaluation of bone metastasis of breast cancer. In this breast cancer case, 99mTc-MDP bone scintigraphy showed normal findings in regards to skeletal metastasis while 18F-FDG-PET/CT, contrast-enhanced CT and MRI revealed multiple metastatic focuses.

Inhibition of NADPH oxidase by glucosylceramide confers chemoresistance

The bioactive sphingolipid ceramide induces oxidative stress by disrupting mitochondrial function and stimulating NADPH oxidase (NOX) activity, both implicated in cell death mechanisms. Many anticancer chemotherapeutics (anthracyclines, Vinca alkaloids, paclitaxel, and fenretinide), as well as physiological stimuli such as tumor necrosis factor α (TNFα), stimulate ceramide accumulation and increase oxidative stress in malignant cells. Consequently, ceramide metabolism in malignant cells and, in particular the up-regulation of glucosylceramide synthase (GCS), has gained considerable interest in contributing to chemoresistance. We hypothesized that increases in GCS activity and thus glucosylceramide, the product of GCS activity, represents an important resistance mechanism in glioblastoma. In our study, we determined that increased GCS activity effectively blocked reactive oxygen species formation by NOX. We further showed, in both glioblastoma and neuroblastoma cells that glucosylceramide directly interfered with NOX assembly, hence delineating a direct resistance mechanism. Collectively, our findings indicated that pharmacological or molecular targeting of GCS, using non-toxic nanoliposome delivery systems, successfully augmented NOX activity, and improved the efficacy of known chemotherapeutic agents.

Glucose metabolism of malignant cells is not regulated by transketolase-like (TKTL)-1

An isoenzyme of transketolase, transketolase-like (TKTL)-1, has been hypothesized to play a pivotal role in the pathophysiology of malignant tumors. Available data are based on the detection of the putative TKTL-1 protein with one particular mouse monoclonal anti-TKTL-1 antibody, clone JFC12T10. In this study it was demonstrated that a) JFC12T10 detects multiple unspecific bands in Western blots, b) a 75-kDa band hitherto referred to as TKTL-1 corresponds to a nuclear protein and c) immunohistochemical detection of TKTL-1 in benign leiomyomas yields an expression pattern identical to that found in a variety of malignant tumors. In RT-PCR assays, using three different primer pairs for transketolase, TKTL-1 and yet another isogene of transketolase, TKTL-2, a relevant expression of TKTL-1 was not detectable in any of the 6 malignant tumor cell lines investigated (MCF-7, A549, HeLa, HT1080, M21 and TF-1). Expression levels of TKTL-1 were rather similar to those found for TKTL-2, although the latter has never been implicated in malignant disease. On the basis of these data, nutritional recommendations based on a hypothetically TKTL-1 controlled metabolism of tumor cells must be regarded as lacking scientific evidence.

Discordant Findings of Skeletal Metastasis Between Tc 99m MDP Bone Scans and F 18 FDG PET/CT Imaging for Advanced Breast and Lung Cancers—Two Case Reports and Literature Review

Traditionally, Tc 99m methyl diphosphate (MDP) bone scintigraphy provides high-sensitivity detection of skeletal metastasis from breast and lung cancers in regular follow-up. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), based on the glucose metabolism of malignant cells, plays a role in describing tumor growth, proliferation of neoplasm and the extent of metastasis. In general, concordant findings of skeletal metastasis are seen on both types of image, especially in cases of breast and lung cancer. However, there were extremely discordant findings of skeletal metastasis between bone scans and F 18 FDG PET/CT imaging in two cases among 300 consecutive F 18 FDG PET/CT follow-up exams of patients with malignancies, during the past year, in our center. Both cases, one of breast cancer and one of lung cancer, had negative bone scintigraphic findings, but a diffusely high grade of F 18 FDG avid marrow infiltration in the axial spine, leading to the diagnosis of stage IV disease in both cases. Owing to variant genetic aberrance of malignance, F 18 FDG PET/CT reveals direct evidence of diffuse, rapid neoplasm metabolism in the bone marrow of the spine, but not of secondary osteoblastic reactions in vivo . F 18 FDG PET/CT should always be employed in the follow-up of patients with malignancies.

Hypertumors in cancer can be caused by tumor phosphorus demand

AbstractIn cancer, tumoral and peritumoral environmental conditions are controlled mostly by the unusual metabolism of malignant cells. For example, tumors typically demand much more phosphorus (P) than normal tissue does, primarily because tumor cells upregulate ribosome biogenesis. Here I use mathematical models to show that this unusual demand for P can lead to a hypertumor, which is a region of highly aggressive cells growing parasitically on the original tumor that can kill all or part of it. Previous work has suggested that hypertumors may develop when a tumor is invaded by an aggressive cell type that fails to secrete angiogenesis factors. In this talk I introduce an entirely different mechanism of hypertumor development. In this case, the aggressive strain upregulates phosphate transporters, leading to increased growth potential, which allows tumor cells to outpace growing blood vessels. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Alpha-tocopheryl succinate (α-TOS) influences cell vitality and enzyme activity in Ehrlich ascites carcinoma cells

Background: One of the most important strategies in research and development of new anticancer agents is the tumor-specific induction of apoptosis. The effects of semisynthetic derivative of vitamin E, (?-TOS, D-?-tocopheryl succinate), appear to be largely restricted to malignant cells. Methods: We investigated the in vivo effects of intraperitoneally administered ?-TOS on vitality of Ehrlich ascites carcinoma cells (EAC) in mice, as well as the influence of ?-TOS on specific activity of enzymes involved in antioxidative mechanisms in EAC cells. Results: According to our results, the intraperitoneal application of ?-TOS induces the decrease of the EAC vitality, and the statistically significant alteration of the glutathione-dependent enzyme activity in EAC cells. Conclusion: We may conclude that ?-TOS is an important micronutrient, with significant impact on vitality and metabolism of malignant cells.

Successful cancer therapy with promethazine: The rationale

Evidence supporting the claim that specific phenothiazines, notably chlorpromazine and promethazine, may be used as sole agents for the treatment of cancer in man, has been reviewed. Selective destruction of cancerous tissue can be achieved by modulating energy metabolism in malignant cells. In the light of available information, the drug of choice is promethazine, the effects of which on the central nervous system are relatively weak. The maintenance of continuous pharmacological pressure against malignant growths forms an essential feature of the therapy. Protection against blood dyscrasias may be secured through the provision of adequate amounts of trace elements necessary for the function of enzyme systems which detoxicate active oxygen species. Tumour-cell death may be facilitated by nutritional supplements of specific polyunsaturated fatty acids. Interference from adventitious medications and drug resistance are discussed; appropriate therapy is outlined.

Cysteine protease and its inhibitor in experimentally produced squamous cell carcinomas in hairless mouse skin

Squamous cell carcinomas (SCC) were experimentally produced in hairless mouse skin, and cysteine protease and its inhibitor were simultaneously purified from extracts of 1 g of tissue of SCC and normal skin. Activity of cysteine proteinases, M r > 50,000 and M r 28,000, increased in SCC compared to those in normal skin. SCC also showed elevation of cysteine proteinase inhibitor activity and M r 13,000 and M r 82,000 inhibitors were purified. M r 13,000 inhibitor was found to have biochemical properties which were the same as those of the inhibitor present in normal skin. M r 82,000 inhibitor was not detectable in normal skin and it differed from a serum inhibitor with a similar M r in terms of activity and stability at acidic pH. The findings suggest that the increased activity of both cysteine proteases and endogenous inhibitors may be involved in the regulatory mechanisms of malignant cell metabolism and tissue remodeling associated with SCC development.

Alterations of serum enzymes during therapy directed at human malignant sarcomas: a radiological follow-up study of tumor transformation

1. When a malignant growth is developing in a patient, one often observes in the serum an increased activity of serum enzymes due to necrosis and increased membrane permeability caused by the altered metabolism of malignant cells. Conversely, I considered it interesting to check the enzymes of the malate-aspartate shuttle in addition to LDH enzyme when a neoplastic growth is regressing due to radiation therapy. The patients who were selected for this study had histologically proved sarcomas (reticulosarcoma, liposarcoma, and post-nosal sarcoma). 2. The data obtained indicated that tumor regression is heralded by progressive decline (to the normal level) of LDH, GOT and MDH activities in serum. Normalization of these systems suggested that reticulosarcoma, liposarcoma, and post-nosal sarcoma are sensitive to the therapeutic agent used. 3. In viewing the data herein reported a definitive conclusion regarding the diagnostic usefulness of these assays is apparent. It seems possible that the measurement of these enzymes in serum of patients with proved sarcomas, may prove to be useful laboratory adjunct to diagnostic radiology and in the management of patients whose diagnosis has already been established.

Abnormal Proteinuria in Malignant Diseases

Publisher Summary Of the many metabolic products of tumors, polypeptides, which belong to the family of immunoglobulins, are perhaps the most readily recognized and have consequently aroused the greatest interest. Secreted in varying amounts by the vast majority of plasmacytic and certain other neoplasms, these proteins can often be detected in the urine and have been the object of intensive investigation since the earliest days of protein chemistry. It is now apparent that numerous proteins associated with the metabolism of malignant cells are excreted in the urine, and, indeed, rather than containing merely “physiological garbage,” the urine has provided a source of “limitless treasure” for investigators in this field. Methods employed for the quantitative determination of proteins in the urine usually vary depending on the protein concentration, whereas the qualitative evaluation of urinary proteins requires a variety of procedures, including electrophoresis in various media, such as filter paper, cellulose acetate, starch gel, immunoelectrophoresis, single or double immunodiffusion analysis, and ultracentrifugation.

A NEW CLASS OF HUMAN IMMUNOGLOBULINS. I. A UNIQUE MYELOMA PROTEIN.

The unique myeloma protein from S. J., a patient with multiple myeloma, was isolated and characterized. It resembled other myeloma proteins in many respects. The S. J. myeloma protein migrated in a distinct peak in the slow beta-globulin region on zone electrophoresis, appeared as a single band on starch gel electrophoresis, and sedimented at 7.04S in the ultracentrifuge. Papain and cysteine treatment produced Fc (fast) and Fab (slow) fragments. Reduction and alkylation of the myeloma protein produced heavy and light chains in a ratio of approximately 3:1. The S. J. myeloma protein had type L (type II) light chains. These were antigenically similar to the Bence Jones protein also found in this patient. The S. J. myeloma protein was unique in the properties of its heavy chains. The myeloma protein (and its heavy chains and Fc pieces) did not contain antigenic determinants specific for IgG, IgA, or IgM. The myeloma protein (and its heavy chains), however, did contain antigenic determinants which are characteristic of a new class of immunoglobulin. The S. J. myeloma protein was unusual also in its effect on the metabolism of normal IgG and in the electrophoretic mobility of the Fc fragment produced by papain digestion. No evidence was obtained to indicate that the entire heavy polypeptide of the S. J. protein was a grossly abnormal product of malignant cell metabolism. The unique properties of the S. J. myeloma protein (and its heavy chains) are believed to represent, in large measure, properties to be found in a small part of the normal immunoglobulin population.

The laboratory diagnosis of extrathyroidal hypermetabolism.

ELEVATION of the basal metabolic rate is frequently misleading in the evaluation of suspected hyperthyroidism. This may be because the BMR indicates total body metabolism and represents the end result of a great many oxidative processes, only one of which is due to the effect of thyroid hormone. Cerebral stimulation, increased metabolism of malignant cells, pregnancy, pheochromocytoma, alterations in hemodynamics such as occur in congestive heart failure, and many other nonthyroid states may notably affect the metabolic rate. Thus, the result is less in error than is its interpretation. This discussion is concerned with the laboratory evaluation of patients referred to a thyroid clinic because of an elevated BMR and in whom the diagnosis of hyperthyroidism was usually considered, if not actually made, by the referring physician. These patients were hospitalized for several days while thyroid metabolic studies were carried out. Many patients were eliminated from this series when previously elevated basal m...