Bacteria-Derived Extracellular Vesicles in Urine as a Novel Biomarker for Gastric Cancer: Integration of Liquid Biopsy and Metagenome Analysis.

Early detection is crucial for improving the prognosis of gastric cancer, but there are no non-invasive markers for the early diagnosis of gastric cancer in real clinical settings. Recently, bacteria-derived extracellular vesicles (EVs) emerged as new biomarker resources. We aimed to evaluate the microbial composition in gastric cancer using bacteria-derived EVs and to build a diagnostic prediction model for gastric cancer with the metagenome data. Stool, urine, and serum samples were prospectively collected from 453 subjects (gastric cancer, 181; control, 272). EV portions were extracted from the samples for metagenome analysis. Differences in microbial diversity and composition were analyzed with 16S rRNA gene profiling, using the next-generation sequencing method. Biomarkers were selected using logistic regression models based on relative abundances at the genus level. The microbial composition of healthy groups and gastric cancer patient groups was significantly different in all sample types. The compositional differences of various bacteria, based on relative abundances, were identified at the genus level. Among the diagnostic prediction models for gastric cancer, the urine-based model showed the highest performance when compared to that of stool or serum. We suggest that bacteria-derived EVs in urine can be used as novel metagenomic markers for the non-invasive diagnosis of gastric cancer by integrating the liquid biopsy method and metagenome analysis.

Rational biosynthetic engineering for optimization of geldanamycin analogues.

Tailor made: We report the rational biosynthesis of C15 hydroxylated non-quinone geldanamycin analogues by site-directed mutagenesis of the geldanamycin polyketide synthase (PKS), together with a combination of post-PKS tailoring genes. Rational biosynthetic engineering allowed the generation of geldanamycin derivatives, such as DHQ3 illustrated in the figure, which had superior pharmacological properties in comparison to the parent compound. A rational biosynthetic engineering approach was applied to the optimization of the pharmacological properties of the benzoquinone ansamycin, geldanamycin. Geldanamycin and its natural or semisynthetic derivatives have the potential to serve as anticancer chemotherapeutic agents. However, these first-generation Hsp90 inhibitors share an unfavorable structural feature that causes both reduced efficacy and toxicity during clinical evaluation. We report the rationally designed biosynthesis of C15 hydroxylated non-quinone geldanamycin analogues by site-directed mutagenesis of the geldanamycin polyketide synthase (PKS), together with a combination of post-PKS tailoring genes. A 15-hydroxyl-17-demethoxy non-quinone analogue, DHQ3, exhibited stronger inhibition of Hsp90 ATPase activity (4.6-fold) than geldanamycin. Taken together, the results of the present study indicate that rational biosynthetic engineering allows the generation of derivatives of geldanamycin with superior pharmacological properties.

Characterization of tailoring genes involved in the modification of geldanamycin polyketide in Streptomyces hygroscopicus JCM4427.

Geldanamycin and its analogs are important anticancer agents that inhibit the newly targeted, heat-shock protein (Hsp) 90, which is a chaperone protein in eukaryotic cells. To resolve which geldanamycin biosynthetic genes are responsible for particular post-polyketide synthase (PKS) processing steps and in which order the reactions occur, we individually inactivated candidate genes in Streptomyces hygroscopicus subsp. duamyceticus JCM4427, and isolated and elucidated the structures of intermediates from each mutant. The results indicated that gel7 governs at least one of the benzoquinone ring oxidation steps. In addition, gel16 was found to be involved in double-bond formation between C-4 and C-5 of 4,5-dihydrogeldanamycin, which confirmed our previous findings that this double bond reduced during the post-PKS modification of the polyketide assembly. In addition, pro-geldanamycin, which does not possess a double bond at C-4/5, was purified from the gel7 and 8 double-gene-inactivated mutant.

Cytotoxic 6-alkylsalicylic acids from the endophytic Streptomyces laceyi.

Two new 6-alkylsalicylic acids, salaceyins A and B were isolated by bioassay-guided fractionation from the culture of the endophytic Streptomyces laceyi MS53 and their structures were determined on the basis of spectroscopic data. Salaceyins A and B exhibited modest cytotoxicity against a human breast cancer cell line (SKBR3) with IC50 values of 3.0 and 5.5 microg/ml, respectively.

Fungal metabolites, sorbicillinoid polyketides and their effects on the activation of peroxisome proliferator-activated receptor gamma.

A new sorbicillinoid polyketide, dihydrotrichodimerol (2), along with known trichodimerol (1), and rezishanones C (3) and D (4) were isolated by bioassay-guided fractionation from an unidentified fungal strain. Dihydrotrichodimerol (2) specifically activated peroxisome proliferator-activated receptor gamma with an ED50 value of 80 ng/ml as measured by a transactivation assay using a chimeric hPPAR/GAL4 system without affecting peroxisome proliferator-activated receptors alpha and sigma. On the other hand, compounds 1 and 2 suppressed the production of tumor necrosis factor-alpha and nitric oxide in LPS-stimulated RAW264.7 cells to a similar extent.

Quantitative trait loci for cold tolerance of rice recombinant inbred lines in low temperature environments.

Low temperature is one of the major environmental stresses in rice cultivation in high-altitude and high-latitude regions. In this study, we cultivated a set of recombinant inbred lines (RIL) derived from Dasanbyeo (indica) / TR22183 (japonica) crosses in Yanji (high-latitude area), Kunming (high-altitude area), Chuncheon (cold water irrigation) and Suwon (normal) to evaluate the main effects of quantitative trait loci (QTL) and epistatic QTL (E-QTL) with regard to their interactions with environments for cold-related traits. Six QTLs for spikelet fertility (SF) were identified in three cold treatment locations. Among them, four QTLs on chromosomes 2, 7, 8, and 10 were validated by several near isogenic lines (NILs) under cold treatment in Chuncheon. A total of 57 QTLs and 76 E-QTLs for nine cold-related traits were identified as distributing on all 12 chromosomes; among them, 19 QTLs and E-QTLs showed significant interactions of QTLs and environments (QEIs). The total phenotypic variation explained by each trait ranged from 13.2 to 29.1% in QTLs, 10.6 to 29.0% in EQTLs, 2.2 to 8.8% in QEIs and 1.0% to 7.7% in E-QTL × environment interactions (E-QEIs). These results demonstrate that epistatic effects and QEIs are important properties of QTL parameters for cold tolerance at the reproductive stage. In order to develop cold tolerant varieties adaptable to wide-ranges of cold stress, a strategy facilitating marker-assisted selection (MAS) is being adopted to accumulate QTLs identified from different environments.