Glutamine Affects Glutathione Recycling Enzymes in a DMBA-Induced Breast Cancer Model

Anticancer role of mango (Mangifera indica L.) peel and seed kernel extracts against 7,12- dimethylbenz[a]anthracene-induced mammary carcinogenesis in female rats

Breast cancer is the second leading cause of cancer death among women. The present study is an effort to reveal the antiproliferative and antioxidant actions of mango seed kernel extract (KE), peel extract (PE), and their combination (KEPE) on mammary tumors induced by 7,12 dimethylbenz[a]anthracene (DMBA). Seven groups of adult female Sprague-Dawley rats were prepared, including C: (control), DMBA: (rats were administered with DMBA), (DMBA-KE), (DMBA-PE), and (DMBA-KEPE): rats were administered with DMBA and then treated with KE, PE, and (both KE and PE), respectively, (KE) and (PE): rats were administered with KE and PE, separately. The study focused on the assessment of markers of endocrine derangement [serum 17-β estradiol (E2)], apoptosis [caspase-3 and deoxyribonucleic acid fragmentation (DNAF)], and oxidative stress [lipid peroxidation and antioxidants (glutathione, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and superoxide dismutase)]. Histopathological examination and immunohistochemical expression of caspase-3 and estrogen receptor-α (ER-α) in mammary gland tissues (MGTs) were determined, as well as the characterization of mango extracts. The results showed that DMBA administration induced mammary tumors by increasing cell proliferation and evading apoptosis. In addition, DMBA administration caused oxidative stress by the production of reactive oxygen species, which increased lipid peroxidation and decreased cellular antioxidants, allowing cancer to progress. In contrast, treatment with DMBA-KE, DMBA-PE, or DMBA-KEPE diminished mammary tumors induced by DMBA, where they reduced oxidative stress via increased antioxidant parameters including reduced glutathione, superoxide dismutase, total glutathione peroxidase, glutathione reductase, and glutathione S-transferase. Also, different treatments decreased proliferation through the reduction of E2, and ER-α expression levels. However, these treatments increased the apoptosis of unwanted cells as they increased caspase-3 activity and DNAF. All these changes led to the prevention of breast injuries and the reduction of mammary tumors. This demonstrates that the contents of mango extracts, especially phenolics and flavonoids, have an important role in mammary tumor treatment through their potential antioxidant, antiproliferative, proapoptotic, and anti-estrogenic effects. KE and PE administration for 4 weeks had no adverse effects. Conclusion: Each of KE, PE, and KEPE has a therapeutic effect against DMBA-induced mammary tumors via induction of apoptosis and reduction of each of the OS, proliferation, and estrogenic effects. So, they can play an important role in the pharmacological tole.

Integrative analysis of multiple cancer prognosis studies with gene expression measurements

Although in cancer research microarray gene profiling studies have been successful in identifying genetic variants predisposing to the development and progression of cancer, the identified markers from analysis of single datasets often suffer low reproducibility. Among multiple possible causes, the most important one is the small sample size hence the lack of power of single studies. Integrative analysis jointly considers multiple heterogeneous studies, has a significantly larger sample size, and can improve reproducibility. In this article, we focus on cancer prognosis studies, where the response variables are progression-free, overall, or other types of survival. A group minimax concave penalty (GMCP) penalized integrative analysis approach is proposed for analyzing multiple heterogeneous cancer prognosis studies with microarray gene expression measurements. An efficient group coordinate descent algorithm is developed. The GMCP can automatically accommodate the heterogeneity across multiple datasets, and the identified markers have consistent effects across multiple studies. Simulation studies show that the GMCP provides significantly improved selection results as compared with the existing meta-analysis approaches, intensity approaches, and group Lasso penalized integrative analysis. We apply the GMCP to four microarray studies and identify genes associated with the prognosis of breast cancer.

Amino acid regulation of mammalian gene expression in the intestine

Some amino acids exert a wide range of regulatory effects on gene expression via the activation of different signalling pathways and transcription factors, and a number of cis elements were shown to respond to changes in amino acid concentration. Particular attention has been paid to the effects of glutamine and arginine, which modulate a number of cell functions through the activation of various pathways in different tissues. In the intestine, appropriate concentrations of both arginine and/or glutamine contribute to facilitate cell proliferation, to limit the inflammatory response and apoptosis, and to modulate intermediary metabolism through specific transcription factors. Particularly, besides its role as a major fuel for enterocytes, the regulatory effects of glutamine have been extensively studied and the molecular mechanisms involved appear diversified and complex. Indeed, in addition to a major role of NF-kappaB in its anti-inflammatory action and a stimulatory role of AP-1 in its growth-promoting action and cell survival, the involvement of some other transcription factors, such as PPAR-gamma or HSF-1, was shown to maintain intestinal cell integrity. The signalling pathways leading to the activation of transcription factors imply several kinases, particularly MAP kinases in the effect of glutamine and p70 S6 kinase for those of arginine, but in most cases the precise pathways from the entrance of the aminoacid into the cell to the activation of gene transcription has remained elusive.

Oral glutamine protects against acute doxorubicin-induced cardiotoxicity of tumor-bearing rats

Doxorubicin (DOX), a widely used anticancer drug, has a dose-dependent cardiotoxicity, attributed mainly to free radical formation. The cardiomyocyte oxidative stress occurs rapidly after DOX treatment, resulting in harmful modifications to proteins, lipids, and DNA. Previous data showed that oral l-glutamine (Gln) prevented cardiac lipid peroxidation and maintained normal cardiac glutathione (GSH) levels in DOX-treated rats. Our aim in this study was to examine the effect of Gln on DOX-induced cardiac oxidative stress in a tumor-bearing host. Female Fisher344 rats with implanted MatBIII mammary tumors were randomized into 2 groups: a Gln group that received l-Gln (1 g.kg(-1).d(-1)) (n = 10) via a Gln-enriched diet and/or gavage with 50% Gln suspension during the whole experiment and a control group that was fed the same diet formulation without Gln and/or were gavaged with water. All rats received a single injection of 12 mg/kg DOX and were killed 3 d later. GSH levels of hearts, livers, tumors, and blood, as well as cardiac histological alterations, lipid peroxidation, peroxinitrite levels, and caspase-3 activation were determined. Cardiac physiologic alterations were assessed by ultrasound imaging before and 3 d after DOX administration. The Gln supplementation resulted in lower cardiac lipid peroxidation and peroxintrite levels and elevated cardiac catalase enzyme activity and GSH compared with the controls, without affecting those of the tumors. DOX-induced alterations of the echocardiographic parameters were significantly reduced in the Gln-supplemented rats. These data indicate that Gln is able to reduce the oxidative damage of cardiomyocytes that occurs soon after DOX administration and thus protects the heart of a tumor-bearing host from DOX-induced cardiomyopathy.

Total parenteral nutrition in children and adolescents treated with high-dose chemotherapy followed by autologous haematopoietic transplants

Total parenteral nutrition (TPN) is still of great importance for haematopoietic stem cell transplantation (HSCT) patients because one of the major adverse effects of the high-dose therapy followed by HSCT is an inadequate oral nutrition intake. The aim of the study was analysis of TPN of young patients in the HSCT period. Twenty-two patients 1·8–20·8 year-old, median 5·4, treated with high-dose therapy and autologous HSCT because of malignancy were included into the study. Grafts contained 1·35–7·9 × 106, median 3·75 × 106CD34+ cells/kg. Engraftment occurred as follows: granulocytes >0·5 × 109/l on +11 d (8–25); platelets >20 × 109/l on +23 d (12–67). Patients were given isoenergetic, isonitrogenous TPN until they consumed less than 50 % of their required diet orally. Proteins intake was 0·8–2·0 g/kg per d, fats intake 1·0–3·0 g/kg per d. Total non-proteins energies–nitrogen grams index was 140:1–200:1. Supplementation of electrolytes, microelements, trace elements and vitamins was dependent on individual patient requirement. TPN duration did not correlate with CD34+cells number but correlated with platelets reconstitution. The assessment of nutritional condition demonstrated no differences in anthropometric parameters, but increase of serum albumin levels after TPN. Requirement for P3 − was above the normal ranges and correlated positively with platelets reconstitution. Requirement for P3 − and K+was higher in patients with mucositis than in other patients. Any complications due to TPN were observed. Adequately composed isoenergetic and isonitrogenous TPN with replacement of electrolytes according to their requirement in the early post-transplantation period allows not only improvement in nutritional status of patients but also could contribute to reconstitution of haematopoiesis.

Dichotomic actions of glutamine in host versus tumour: an emerging concept

PURPOSE OF REVIEW

Malignancy is characterized by a systemic deficiency of glutamine (GLN). The debate over whether GLN supplementation should be standard of cancer patients is still topical. This review focuses on recent findings on the effect of GLN administration on the incidence and severity of adverse effects in host due to radiotherapy or chemotherapy or both and on its putative adjuvant role on cytotoxicity of radiotherapy and chemotherapy on tumour.

RECENT FINDINGS

Animal and human studies have reported that high-dose GLN supplementation could prevent gastrointestinal tract injury after radiotherapy and chemotherapy. Animal studies are suggesting that GLN could actually decrease tumour growth by upregulating the immune system and through a regulation of the redox status associated to the metabolism of glutathione. GLN could enhance the selectivity of antitumour drugs by protecting normal tissues from chemotherapy and by sensitizing tumour cells to chemotherapy.

SUMMARY

Recent studies have shown that GLN could have dichotomic actions in host versus in tumour, probably in link with glutathione metabolism, suggesting that GLN could be used in clinical practice to increase the therapeutic index of oncological treatments.

Control of mammalian gene expression by amino acids, especially glutamine

Molecular data rapidly accumulating on the regulation of gene expression by amino acids in mammalian cells highlight the large variety of mechanisms that are involved. Transcription factors, such as the basic-leucine zipper factors, activating transcription factors and CCAAT/enhancer-binding protein, as well as specific regulatory sequences, such as amino acid response element and nutrient-sensing response element, have been shown to mediate the inhibitory effect of some amino acids. Moreover, amino acids exert a wide range of effects via the activation of different signalling pathways and various transcription factors, and a number of cis elements distinct from amino acid response element/nutrient-sensing response element sequences were shown to respond to changes in amino acid concentration. Particular attention has been paid to the effects of glutamine, the most abundant amino acid, which at appropriate concentrations enhances a great number of cell functions via the activation of various transcription factors. The glutamine-responsive genes and the transcription factors involved correspond tightly to the specific effects of the amino acid in the inflammatory response, cell proliferation, differentiation and survival, and metabolic functions. Indeed, in addition to the major role played by nuclear factor-kappaB in the anti-inflammatory action of glutamine, the stimulatory role of activating protein-1 and the inhibitory role of C/EBP homology binding protein in growth-promotion, and the role of c-myc in cell survival, many other transcription factors are also involved in the action of glutamine to regulate apoptosis and intermediary metabolism in different cell types and tissues. The signalling pathways leading to the activation of transcription factors suggest that several kinases are involved, particularly mitogen-activated protein kinases. In most cases, however, the precise pathways from the entrance of the amino acid into the cell to the activation of gene transcription remain elusive.

Glutamine in neoplastic cells: focus on the expression and roles of glutaminases

Glutamine is an important source of energy for neoplastic tissues, and products of its metabolism include, among others, glutamate (Glu) and glutathione (GSH), the two molecules that play a key role in tumor proliferation, invasiveness and resistance to therapy. Glutamine hydrolysis in normal and transforming mammalian tissues alike, is carried out by different isoforms of glutaminases, of which the two major are liver-type glutaminase (LGA) and kidney-type glutaminase (KGA). This brief review summarizes available data on the expression profiles and activities of these isoenzymes in different neoplastic tissues as compared to the tissues of origin, and dwells on recent work demonstrating effects of manipulation of glutaminase expression on tumor growth. A comment is devoted to the emerging evidence that LGA, apart from degrading Gln for metabolic purposes, is involved in gene transcription; its enforced overexpression in glioma cells was found to reduce their proliferation and migration.