Multiple exo-glycosidases in human serum as detected with the substrate DNP-α-GalNAc. II. Three α-N-acetylgalactosaminidase-like activities in the pH 5 to 8 region

Effect of Phlorotannins from Brown Algae Costaria costata on α-N-Acetylgalactosaminidase Produced by Duodenal Adenocarcinoma and Melanoma Cells

The inhibitor of human α-N-acetylgalactosaminidase (α-NaGalase) was isolated from a water-ethanol extract of the brown algae Costaria costata. Currently, tumor α-NaGalase is considered to be a therapeutic target in the treatment of cancer. According to NMR spectroscopy and mass spectrometric analysis, it is a high-molecular-weight fraction of phlorethols with a degree of polymerization (DP) equaling 11-23 phloroglucinols (CcPh). It was shown that CcPh is a direct inhibitor of α-NaGalases isolated from HuTu 80 and SK-MEL-28 cells (IC50 0.14 ± 0.008 and 0.12 ± 0.004 mg/mL, respectively) and reduces the activity of this enzyme in HuTu 80 and SK-MEL-28 cells up to 50% at concentrations of 15.2 ± 9.5 and 5.7 ± 1.6 μg/mL, respectively. Molecular docking of the putative DP-15 oligophlorethol (P15OPh) and heptaphlorethol (PHPh) with human α-NaGalase (PDB ID 4DO4) showed that this compound forms a complex and interacts directly with the Asp 156 and Asp 217 catalytic residues of the enzyme in question. Thus, brown algae phlorethol CcPh is an effective marine-based natural inhibitor of the α-NaGalase of cancer cells and, therefore, has high therapeutic potential.

Immunotherapy with GcMAF revisited - A critical overview of the research of Nobuto Yamamoto

This overview describes the research of Nobutu Yamamoto (Philadelphia) concerning immunotherapy with GcMAF for patients with cancer and for patients infected with pathogenic envelope viruses. GcMAF (Group-specific component Macrophage-Activating Factor) is a mammalian protein with an incredible potency to directly activate macrophages. Since the late 1980s Yamamoto's investigations were published in numerous journals but in order to understand the details of his research, a minute survey of many of his patents was required. But even then, regrettably, a precise description of his experiments was sometimes lacking. This overview tries to summarize all of Yamamoto's research on GcMAF, as well as some selected more recent papers from other investigators, who tried to verify and/or reproduce Yamamoto's reports. In my opinion the most important result of the GcMAF research deserves widespread renewed attention: human GcMAF injections (100 ng per week, intramuscular or intravenous) can help to cure patients with a great variety of cancers as well as patients infected with pathogenic envelope viruses like the human immunodeficiency virus 1 (HIV-1), influenza, measles and rubella (and maybe also SARS-CoV-2). From Yamamoto's data it can be calculated that GcMAF is a near-stoichiometric activator of macrophages. Yamamoto monitored the progress of his immunotherapy via the serum level of an enzyme called nagalase (α-N-acetylgalactosaminidase activity at pH 6). I have extensively discussed the properties and potential catalytic site of this enzyme activity in an Appendix entitled: "Search for the potential active site of the latent α-N-acetylgalactosaminidase activity in the glycoproteins of some envelope viruses".

Silencing of α-N-acetylgalactosaminidase in the gastric cancer cells amplified cell death and attenuated migration, while the multidrug resistance remained unchanged

Although the elevated level of the α-N-acetylgalactosaminidase enzyme (encoded by the NAGA gene) is a well-recognized feature of cancer cells; little research works have been undertaken on the cancer malignancy mechanisms. The effects of NAGA gene downregulation on cancer cells' features such as drug resistance, impaired programmed cell death, and migration were analyzed in this study. The cells grew exponentially with a doubling time of 30 h in an optimal condition. Toxicity of daunorubicin chemotherapy drug on NAGA-transfected EPG85.257RDB cells was evaluated in comparison to control cells and no significant change was recorded. Quantitative transcript analyses and protein levels revealed that the MDR1 pump almost remained unchanged during the study. Moreover, the NAGA gene downregulation enhanced the late apoptosis rate in EPG85.257RDB cells at 24 h posttransfection. The investigated expression level of genes and proteins involved in the TNFR2 signaling pathway, related to cancer cell apoptosis, showed considerable alterations after NAGA silencing as well. MAP3K14 and CASP3 genes were downregulated while IL6, RELA, and TRAF2 experienced an upregulation. Also, NAGA silencing generally diminished the migration ability of EPG85.257RDB cells and the MMP1 gene (as a critical gene in metastasis) expression decreased significantly. The expression of the p-FAK protein, which is located in the downstream of the α₂ β₁ integrin signaling pathway, was reduced likewise. It could be concluded that despite drug resistance, NAGA silencing resulted in augmentative and regressive effects on cell death and migration.

Effects of Sponge-Derived Alkaloids on Activities of the Bacterial α-D-Galactosidase and Human Cancer Cell α-N-Acetylgalactosaminidase

During a search for glycosidase inhibitors among marine natural products, we applied an integrated in vitro and in silico approach to evaluate the potency of some aaptamines and makaluvamines isolated from marine sponges on the hydrolyzing activity of α-N-acetylgalactosaminidase (α-NaGalase) from human cancer cells and the recombinant α-D-galactosidase (α-PsGal) from a marine bacterium Pseudoalteromonas sp. KMM 701. These alkaloids showed no direct inhibitory effect on the cancer α-NaGalase; but isoaaptamine (2), 9-demethylaaptamine (3), damirone B (6), and makaluvamine H (7) reduced the expression of the enzyme in the human colorectal adenocarcinoma cell line DLD-1 at 5 μM. Isoaaptamine (2), 9-demethylaaptamine (3), makaluvamine G (6), and zyzzyanone A (7) are slow-binding irreversible inhibitors of the bacterial α-PsGal with the inactivation rate constants (k_inact) 0.12 min⁻¹, 0.092 min⁻¹, 0.079 min⁻¹, and 0.037 min⁻¹, as well as equilibrium inhibition constants (K_i) 2.70 µM, 300 µM, 411 µM, and 105 µM, respectively. Docking analysis revealed that these alkaloids bind in a pocket close to the catalytic amino acid residues Asp451 and Asp516 and form complexes, due to π-π interactions with the Trp308 residue and hydrogen bonds with the Lys449 residue. None of the studied alkaloids formed complexes with the active site of the human α-NaGalase.

Multiple exo-glycosidases in human serum as detected with the substrate DNP-α-GalNAc. I. A new assay for lysosomal α-N-acetylgalactosaminidase

This paper presents a new assay to determine the activity of the lysosomal enzyme α-N-acetylgalactosaminidase (Naga, EC 3.2.1.49) in human serum. It is based on the use of a new chromogenic substrate, DNP-α-GalNAc (2,4-dinitrophenyl-N-acetyl-α-D-galactosaminide) and is performed at pH 4.3 and 37 °C. This allows continuous monitoring of the absorbance of the released DNP. The assay can be performed with a standard spectrophotometer. Compared to established methods using an endpoint assay with MU-α-GalNAc (4-methylumbelliferyl-GalNAc), the present method gives a ca. 3-fold higher specific activity, while only one tenth of the serum concentration in the assay is required. Hence, the assay is at least 30-fold more sensitive than that with MU-α-GalNAc. The pH dependence of the reaction with DNP-α-GalNAc in the pH 3.5 to 6.5 region, while using 4% serum in the assay, shows only one peak around pH 4. This pH optimum is similar to that reported with MU-α-GalNAc. In the accompanying paper (S.P.J Albracht and J. Van Pelt (2017) Multiple exo-glycosidases in human serum as detected with the substrate DNP-α-GalNAc. II. Three α-N-acetylgalactosaminidase-like activities in the pH 5 to 8 region. BBA Clin. 8 (2017) 90-96), the method is used to show that, under special assay conditions, three more Naga-like activities can be uncovered in human serum.