Differential Inhibition of Anaplerotic Pyruvate Carboxylation and Glutaminolysis-Fueled Anabolism Underlies Distinct Toxicity of Selenium Agents in Human Lung Cancer.

Past chemopreventive human trials on dietary selenium supplements produced controversial outcomes. They largely employed selenomethionine (SeM)-based diets. SeM was less toxic than selenite or methylseleninic acid (MSeA) to lung cancer cells. We thus investigated the toxic action of these Se agents in two non-small cell lung cancer (NSCLC) cell lines and ex vivo organotypic cultures (OTC) of NSCLC patient lung tissues. Stable isotope-resolved metabolomics (SIRM) using 13C6-glucose and 13C5,15N2-glutamine tracers with gene knockdowns were employed to examine metabolic dysregulations associated with cell type- and treatment-dependent phenotypic changes. Inhibition of key anaplerotic processes, pyruvate carboxylation (PyC) and glutaminolysis were elicited by exposure to MSeA and selenite but not by SeM. They were accompanied by distinct anabolic dysregulation and reflected cell type-dependent changes in proliferation/death/cell cycle arrest. NSCLC OTC showed similar responses of PyC and/or glutaminolysis to the three agents, which correlated with tissue damages. Altogether, we found differential perturbations in anaplerosis-fueled anabolic pathways to underlie the distinct anti-cancer actions of the three Se agents, which could also explain the failure of SeM-based chemoprevention trials.

Hannaella dianchiensis sp. nov., a basidiomycetous yeast species isolated from lake water.

Three strains (YIM-HL1107T, YIM-HL1045, YIM-HL1112) representing a novel yeast species were isolated from surface water samples collected from the Caohai region of Dianchi Lake in Yunnan, south-western China. On the basis of morphological, physiological and biochemical characteristics and sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region, they were assigned to a novel species of the genus Hannaella. The closest relative to the novel species was Hannaella pagnoccae, but it showed 6.3 % nucleotide differences (34 nt substitutions out of 541 nt) in the D1/D2 region of the LSU rRNA gene and 9.3-9.6 % nucleotide differences (40-41 substitutions and 7-8 gaps out of 430 nt) in the ITS region. The name Hannaella dianchiensis sp. nov. is proposed. The type strain is YIM-HL1107T (=CBS 14191T=CCTCC AY 2015009T), and the MycoBank number is MB 816297.