Classical Metabolic Pathway Research Articles

Targeting metabolism to enhance immunotherapy within tumor microenvironment.

Cancer metabolic reprogramming has been considered an emerging hallmark in tumorigenesis and the antitumor immune response. Like cancer cells, immune cells within the tumor microenvironment or premetastatic niche also undergo extensive metabolic reprogramming, which profoundly impacts anti-tumor immune responses. Numerous evidence has illuminated that immunosuppressive TME and the metabolites released by tumor cells, including lactic acid, Prostaglandin E2 (PGE2), fatty acids (FAs), cholesterol, D-2-Hydroxyglutaric acid (2-HG), adenosine (ADO), and kynurenine (KYN) can contribute to CD8+ T cell dysfunction. Dynamic alterations of these metabolites between tumor cells and immune cells can similarly initiate metabolic competition in the TME, leading to nutrient deprivation and subsequent microenvironmental acidosis, which impedes immune response. This review summarizes the new landscape beyond the classical metabolic pathways in tumor cells, highlighting the pivotal role of metabolic disturbance in the immunosuppressive microenvironment, especially how nutrient deprivation in TME leads to metabolic reprogramming of CD8+ T cells. Likewise, it emphasizes the current therapeutic targets or strategies related to tumor metabolism and immune response, providing therapeutic benefits for tumor immunotherapy and drug development in the future. Cancer metabolic reprogramming has been considered an emerging hallmark in tumorigenesis and the antitumor immune response. Dynamic alterations of metabolites between tumor cells and immune cells initiate metabolic competition in the TME, leading to nutrient deprivation and subsequent microenvironmental acidosis, which impedes immune response.

Aerobic degradation of 2,4,6-trinitrophenol by Proteus sp. strain OSES2 obtained from an explosive contaminated tropical soil

A 2,4,6-trinitrophenol (TNP) degrading bacterial strain isolated from a site polluted with explosives was identified as Proteus sp. strain OSES2 via 16S rRNA gene sequencing. Metabolic investigation showed that the organism grew exponentially on 100mg l-1 of TNP as a source of carbon, nitrogen, and energy. In addition, the growth of the organism was sustainable on 3-nitrotoluene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, 4-nitrophenol, methyl-3-nitrobenzoate, 4-nitroaniline, aniline and nitrobenzene. Strain OSES2 was able to utilize TNP within a concentration range of 100mg l-1 to 500mg l-1. The specific growth rate and degradation rates on TNP were 0.01043h-1 and 0.01766mg l-1h-1 respectively. Effective degradation of TNP in a chemically defined medium was evident with a gradual reduction in the concentration of TNP concomitant with an increase in cell density as well as the substantial release of ammonium (NH4+), nitrite (NO2-), and nitrate (NO3-) as metabolites in 96h. Degradation competence of the organism was enhanced in the presence of starch and acetate. On starch-supplemented TNP, the highest specific growth rate and degradation rates were 0.02634h-1 and 0.04458mg l-1h-1, respectively, while the corresponding values on acetate were 0.02341h-1 and 0.02811mg l-1h-1. However, amendment with nitrogen sources yielded no substantial improvement in degradation. TNP was utilized optimally at pH 7 to 9 and within the temperature range of 30°C to 37°C. The enzyme hydride transferase II [HTII], encoded by the npdI gene which is the first step involved in the TNP degradation pathway, was readily expressed by the isolate thus suggesting that substrate was utilized through the classical metabolic pathway.

Abstract 1440: Vitamin D uptake and metabolism in breast cancer tumors: Differential expression of megalin, VDR, CYP27B1 and CYP24A

Abstract Diverse studies have concluded that Vitamin D plays a main role of in breast cancer risk. The active metabolite of vitamin D, is a pleiotropic hormone that regulates proliferation, survival, and differentiation of many cell types, through its nuclear receptor VDR. Clinical and epidemiological studies have described the association of decreased serum concentrations of 25-hydroxy-vitamin D with a poor prognosis in patients with breast cancer. The metabolism of vitamin D is meticulously regulated through a complex process, involving the vitamin D-activating enzyme CYP27B1, responsible for the final hydroxylation step to form the active metabolite and CYP24A1, the key enzyme in the inactivation of this metabolite. It is also known that VDR is central for vitamin D-mediated transcription regulation. For all these processes it is necessary that vitamin D enters the cell. In the kidney, internalization of the circulating vitamin D is accomplished by megalin, a membrane receptor for vitamin D, which has not been defined in mammary tissue. Until today reports published in relation to the mechanism of vitamin D uptake and its metabolism are scarce in breast cancer tumors. Our aim was to quantify the expression and to determine the localization of: megalin, VDR, CYP27B1 and CYP24A1 enzymes in breast cancer tumor tissues and normal breast tissue. For this purpose, tissue microarrays of formalin-fixed and paraffin-embedded tumor samples and normal breast tissues were analyzed through immunohistochemistry. This study showed that megalin is localized apically in epithelial cells of normal breast tissue, as previously described in the kidney. On the other hand, in breast cancer tumors megalin expression was diminished. Interestingly, we found that megalin had a different localization in two breast cancer tumor subtypes. In luminal breast cancer tumors, megalin was localized mainly in the cellular membrane whereas in triple negative tumors we observed a cytoplasmic localization. For VDR, CYP27B1 and CYP24A1 our results showed that all these proteins are expressed in normal breast tissues. VDR and CYP24A1 have a heterogeneous expression in relation to tumor subtypes and these are highly expressed in all luminal breast cancer tumors, whereas in triple negative breast cancer subtype its expression was low. Our results suggest that exists an alteration in classical metabolic pathway of vitamin D in the tumor subtypes analyzed of breast cancer. With these results we can suggest that in luminal tumors, which have the better prognosis compared with other subtypes, tumor cells still to respond to vitamin D, while in triple negative subtype, the tumor cells reduce their ability to: uptake, catabolize the active metabolite and respond to vitamin D favoring tumor progression. Citation Format: Gabriela Valarezo, Victoria Ortega-Hernández, Gonzalo Escobar-Massú, Wanda Fernández, María Paz Marzolo, Pilar Carvallo. Vitamin D uptake and metabolism in breast cancer tumors: Differential expression of megalin, VDR, CYP27B1 and CYP24A [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1440.

The structure of sugar chains of Japanese quail ovomucoid. The occurrence of oligosaccharides not expected from the classical biosynthetic pathway for N-glycans; a method for the assessment of the structure of glycans present in picomolar amounts.

While the structure of the major oligosaccharide of Japanese quail ovomucoid was reported earlier (Hase, S. et al. (1982) J. Biochem. 91, 735-737), the structures of the minor oligosaccharide units were investigated for the first time in the present studies. For this purpose, the glycans of the protein were liberated from the polypeptide chain by hydrazinolysis. After N-acetylation, the reducing ends of the oligosaccharides obtained were coupled with 2-aminopyridine, and then the resulting fluorescent derivatives were purified by Bio-Gel P-2 column chromatography and reversed-phase HPLC. The chemical structures of two minor oligosaccharide units were determined with the aid of exoglycosidases, and by methylation analysis and Smith degradation. The results demonstrated that the ovomucoid contains the following two monoantennary glycans: Man alpha 1-6(Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc and Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc. The latter structure was not predicted by the classical metabolic pathway for the N-glycans to be formed. The structures of three additional minor heterosaccharides were deduced from their elution positions on HPLC together with the results of determination of their molecular sizes and the HPLC elution positions of their enzymatic degradation products. It is noteworthy that for the latter procedure for the estimation of the structures of oligosaccharides only minute quantities of glycans (several hundreds pmol) are required.

Lack of Effect of Thiamine Deficiency on Oxidation of Methylglyoxal-14C in the Rat

The effect of thiamine deficiency on the in vivo oxidation of methylglyoxal-1,3-14C and methylglyoxal-2-14C to 14CO2 was studied in the rat. The rapidity with which the 14C label appeared in the expired CO2 favors the interpretation that methylglyoxal metabolism is not impaired in the thiamine-deficient rat. The appearance of 14C label in liver glycogen and urine keto acids also indicated that it rapidly entered the classical metabolic pathways. The data suggest a rapid transformation of methylglyoxal to pyruvate and entrance into the Krebs cycle.