Antiproliferative cyclodepsipeptides from the marine actinomycete Streptomyces sp. P11-23B downregulating the tumor metabolic enzymes of glycolysis, glutaminolysis, and lipogenesis

Two cyclodepsipeptides and a known cyclodepsipeptide valinomycin were isolated from a culture of the marine actinomycete Streptomyces sp. P11-23B. Their structures were established based on NMR, HRESIMS, and MS-MS spectroscopic interpretation as well as by chemical degradation. Both streptodepsipeptides P11A and P11B inhibited proliferation of different glioma cell lines, with IC₅₀ values ranging from 0.1 μM to 1.4 μM. Streptodepsipeptide P11A was found to block the cell cycle at the G₀/G₁ phase and induce apoptosis in glioma cells. Further investigation demonstrated that streptodepsipeptide P11A downregulated expression of HK2, PFKFB3, PKM2, GLS, and FASN, important tumor metabolic enzymes. Data from this study suggested that targeting multiple tumor metabolic regulators might be one anti-glioma mechanism of streptodepsipeptide P11A. A possible mechanism for this class of streptodepsipeptides is reported herein.

The toxic function of cesium 5-sulfosalicylate based on the investigation of its trans-erythrocytes membrane behaviors and morphological properties

In order to evaluate the cesium-induced toxic functional changes in organisms, transmembrane activities of cesium 5-sulfosalicylate (Cs(H(2)Ssal)) into human erythrocyte in vitro is presented in this paper, including kinetic characteristic of transport process and pathways involved in it. The uptake amount of Cs(H(2)Ssal) by erythrocyte was determined both by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and spectrofluorimetry. The pathways of Cs(H(2)Ssal) transporting into erythrocyte are proposed according to inhibition investigation. The influence of Cs(H(2)Ssal) on morphological properties of erythrocytes was examined using Scanning Electron Microscopy (SEM) to determined the endurable concentration extent of erythrocytes to Cs(H(2)Ssal). Results show that transmembrane of Cs(H(2)Ssal) has characteristic of first-order kinetic process during the first 2h, and four pathways were involved in its transporting activities: Ca(2+) channel, Na(+)-K(+) pump, Na(+)-Cs(+) countertransport, and anion Cl(-)/CsCO(3)(-) exchange. The transmembrane process of Cs(H(2)Ssal) can both prevent the uptake of K(+) and induces abnormal accumulation of extracellular K(+) as well as occupy some K(+)-binding sites in protein, causing some tissues losing their activities and functions. Only high concentrations of Cs(H(2)Ssal) could change morphological properties of erythrocytes greatly and cause hemolysis eventually.