Neosetophomone B induces apoptosis in multiple myeloma cells via targeting of AKT/SKP2 signaling pathway

Multiple myeloma (MM) is a hematologic malignancy associated with malignant plasma cell proliferation in the bone marrow. Despite the available treatments, drug resistance and adverse side effects pose significant challenges, underscoring the need for alternative therapeutic strategies. Natural products, like the fungal metabolite neosetophomone B (NSP-B), have emerged as potential therapeutic agents due to their bioactive properties. Our study investigated NSP-B's antitumor effects on MM cell lines (U266 and RPMI8226) and the involved molecular mechanisms. NSP-B demonstrated significant growth inhibition and apoptotic induction, triggered by reduced AKT activation and downregulation of the inhibitors of apoptotic proteins and S-phase kinase protein. This was accompanied by an upregulation of p21Kip1 and p27Cip1 and an elevated Bax/BCL2 ratio, culminating in caspase-dependent apoptosis. Interestingly, NSP-B also enhanced the cytotoxicity of bortezomib (BTZ), an existing MM treatment. Overall, our findings demonstrated that NSP-B induces caspase-dependent apoptosis, increases cell damage, and suppresses MM cell proliferation while improving the cytotoxic impact of BTZ. These findings suggest that NSP-B can be used alone or in combination with other medicines to treat MM, highlighting its importance as a promising phytoconstituent in cancer therapy.     

A conserved RNA structure within the HCV IRES eIF3-binding site

The hepatitis C virus (HCV) internal ribosome entry site (IRES) is recognized specifically by the small ribosomal subunit and eukaryotic initiation factor 3 (eIF3) before viral translation initiation. Using extensive mutagenesis and structure probing analysis, we show that the eIF3-binding domain of the HCV IRES contains an internal loop structure (loop IIIb) and an adjacent mismatched helix that are important for IRES-dependent initiation of translation. NMR studies reveal a unique three-dimensional structure for this internal loop that is conserved between viral isolates of varying primary sequence in this region. These data indicate that internal loop IIIb may be an attractive target for structure-based design of new antiviral agents.     

Human apolipoprotein B: identification of cDNA clones and characterization of mRNA.

Apolipoprotein B (apoB) is a major protein component of low density and very low density lipoproteins. Because of its large size and heterogeneity, molecular studies of apoB have been difficult, and its structure and regulation remain poorly understood. We now report the identification of human apoB cDNA clones by antibody screening of hepatoma libraries in the expression vector lambda gt11. Both oligo(dT) primed and random primed libraries were constructed and screened with polyclonal antibodies to intact apoB, as well as with antibodies raised against a synthetic peptide based on the limited amino acid sequence available for apoB. The identity of the clones was unambiguously established by comparisons of the cloned cDNA sequences with apoB amino acid sequences. The clones hybridize to an exceptionally large 20 kb mRNA that is present in liver and intestine but not other tissues examined, consistent with the distribution expected from protein biosynthetic studies. The properties of the mRNA have implications for the biogenesis of the multiple apoB molecular weight forms secreted by liver and intestine.     

Chloroquine inhibits glutamate-induced death of a neuronal cell line by reducing reactive oxygen species through sigma-1 receptor

Chloroquine, a widely used anti-malarial and anti-rheumatoid agent, has been reported to induce apoptotic and non-apoptotic cell death. Accumulating evidence now suggests that chloroquine can sensitize cancer cells to cell death and augment chemotherapy-induced apoptosis by inhibiting autophagy. However, chloroquine is reported to induce GM1 ganglioside accumulation in cultured cells at low μM concentrations and prevent damage to the blood brain barrier in mice. It remains unknown whether chloroquine has neuroprotective properties at concentrations below its reported ability to inhibit lysosomal enzymes and autophagy. In the present study, we demonstrated that chloroquine protected mouse hippocampal HT22 cells from glutamate-induced oxidative stress by attenuating production of excess reactive oxygen species. The concentration of chloroquine required to rescue HT22 cells from oxidative stress was much lower than that sufficient enough to induce cell death and inhibit autophagy. Chloroquine increased GM1 level in HT22 cells at low μM concentrations but glutamate-induced cell death occurred before GM1 accumulation, suggesting that GM1 induction is not related to the protective effect of chloroquine against glutamate-induced cell death. Interestingly, BD1047 and NE-100, sigma-1 receptor antagonists, abrogated the protective effect of chloroquine against glutamate-induced cell death and reactive oxygen species production. In addition, cutamesine (SA4503), a sigma-1 receptor agonist, prevented both glutamate-induced cell death and reactive oxygen species production. These findings indicate that chloroquine at concentrations below its ability to inhibit autophagy and induce cell death is able to rescue HT22 cells from glutamate-induced cell death by reducing excessive production of reactive oxygen species through sigma-1 receptors. These results suggest potential use of chloroquine, an established anti-malarial agent, as a neuroprotectant against oxidative stress, which occurs in a variety of neurodegenerative diseases.     

Inhibition of factor X, factor V and prothrombin activation by the bis(lactobionic acid amide) LW10082.

The minimum concentrations of heparin, dermatan sulfate, hirudin, and D-Phe-Pro-ArgCH2Cl required to delay the onset of prothrombin activation in contact-activated plasma also prolong the lag phases associated with both factor X and factor V activation. Heparin and dermatan sulfate prolong the lag phases associated with the activation of the three proteins by catalyzing the inhibition of endogenously generated thrombin. Thrombin usually activates factor V and factor VIII during coagulation. The smallest fragment of heparin able to catalyze thrombin inhibition by antithrombin III is an octadecasaccharide with high affinity for antithrombin III. In contrast, a dermatan sulfate hexasaccharide with high affinity for heparin cofactor II can catalyze thrombin inhibition by heparin cofactor II. A highly sulfated bis(lactobionic acid amide), LW10082 (Mr 2288), which catalyzes thrombin inhibition by heparin cofactor II and has both antithrombotic and anticoagulant activities, has been synthesized. In this study, we determined how the minimum concentration of LW10082 required to delay the onset of intrinsic prothrombin activation achieved this effect. We demonstrate that, like heparin and dermatan sulfate, LW10082 delays the onset of intrinsic prothrombin activation by prolonging the lag phase associated with both factor X and factor V activation. In addition, LW10082 is approximately 25% as effective as heparin and 10 times as effective as dermatan sulfate in its ability to delay the onset of prothrombin activation. The strong anticoagulant action of LW10082 is consistent with previous reports which show that the degree of sulfation is an important parameter for the catalytic effectiveness of sulfated polysaccharides on thrombin inhibition.     

24-Epibrassinolide alleviates salt-induced inhibition of productivity by increasing nutrients and compatible solutes accumulation and enhancing antioxidant system in wheat (Triticum aestivum L.)

Two wheat (Triticum aestivum L.) cultivars, Sids 1 and Giza 168, were grown under non-saline or saline conditions (4.7 and 9.4 dS m^?1) and were sprayed with 0.00, 0.05 and 0.10 mg l^?1 24-epibrassinolide (EBL). Salt stress markedly decreased plant productivity and N, P, and K uptake, particularly in Giza 168. A follow-up treatment with 0.1 mg l^?1 EBL detoxified the stress generated by salinity and considerably improved the above parameters, especially in Sids 1. Organic solutes (soluble sugars, free amino acids, proline and glycinebetaine), antioxidative enzymes (superoxide dismutase, peroxidase, catalase and glutathione reductase), antioxidant molecules (glutathione and ascorbate) and Ca and Mg levels were increased under saline condition, and these increases proved to be more significant in salt-stressed plants sprayed with EBL, particularly at 0.1 mg l^?1 EBL with Sids 1. Sodium concentration, lipid peroxidation, hydrogen peroxide content and electrolyte leakage were increased under salt stress and significantly decreased when 0.1 mg l^?1 EBL was sprayed. Clearly, EBL alleviates salt-induced inhibition of productivity by altering the physiological and biochemical properties of the plant.     

Structural investigations of the extracellular polysaccharide elaborated by s19, a Xanthomonas-type bacterium

The extracellular, acidic heteropolysaccharide from Xanthomonas S19 consists of D-glucuronic acid, D-glucose, D-galactose, and D-mannose residues in the approximate molar ratios of 1.6:3:1:1, plus acetyl groups liked to C-2 and/or C-3 of a large proportion of the glucose residues. Methylation studies showed that the glucose is present as non-reducing end-group also as 1,2- and 1,4-linked units, the galactose residues are solely 1,3-linked, a major proportion of the mannose residues are 1,2,4-linked and the rest 1,2-linked. A high proportion of the glucuronic acid units are 1,4-linked. Periodate oxidation confirmed the presence of these linkages. The disaccharides D-Glc-(1→4)-D-Glc,D-Glc-(1→2)-D-Man, D-Glc-(1→3)-D-Gal, D-Gal-(1→2)-D-Glc, D-GlcA-(1→4)-D-GlcA, and β-D-GlcA-(1→4)-D-Man were isolated from a partial hydrolysate of the polysaccharide, and characterised. The similarities and differences between this polysaccharide and those from other Xanthomonas species are discussed.