BackgroundGram-negative bacteria of the genus Serratia are potential producers of many useful secondary metabolites, such as prodigiosin and serrawettins, which have potential applications in environmental bioremediation or in the pharmaceutical industry. Several Serratia strains produce prodigiosin and serrawettin W1 as the main bioactive compounds, and the biosynthetic pathways are co-regulated by quorum sensing (QS). In contrast, the Serratia strain, which can simultaneously produce prodigiosin and serrawettin W2, has not been reported. This study focused on analyzing the genomic sequence of Serratia sp. strain YD25T isolated from rhizosphere soil under continuously planted burley tobacco collected from Yongding, Fujian province, China, which is unique in producing both prodigiosin and serrawettin W2.ResultsA hybrid polyketide synthases (PKS)-non-ribosomal peptide synthetases (NRPS) gene cluster putatively involved in biosynthesis of antimicrobial serrawettin W2 was identified in the genome of YD25T, and its biosynthesis pathway was proposed. We found potent antimicrobial activity of serrawettin W2 purified from YD25T against various pathogenic bacteria and fungi as well as antitumor activity against Hela cells. Subsequently, comparative genomic analyses were performed among a total of 133 Serratia species. The prodigiosin biosynthesis gene cluster in YD25T belongs to the type I pig cluster, which is the main form of pig-encoding genes existing in most of the pigmented Serratia species. In addition, a complete autoinducer-2 (AI-2) system (including luxS, lsrBACDEF, lsrGK, and lsrR) as a conserved bacterial operator is found in the genome of Serratia sp. strain YD25T. Phylogenetic analysis based on concatenated Lsr and LuxS proteins revealed that YD25T formed an independent branch and was clearly distant from the strains that solely produce either prodigiosin or serrawettin W2. The Fe (III) ion reduction assay confirmed that strain YD25T could produce an AI-2 signal molecule. Phylogenetic analysis using the genomic sequence of YD25T combined with phylogenetic and phenotypic analyses support this strain as a member of a novel and previously uncharacterized Serratia species.ConclusionGenomic sequence and metabolite analysis of Serratia surfactantfaciens YD25T indicate that this strain can be further explored for the production of useful metabolites. Unveiling the genomic sequence of S. surfactantfaciens YD25T benefits the usage of this unique strain as a model system for studying the biosynthesis regulation of both prodigiosin and serrawettin W2 by the QS system.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3171-7) contains supplementary material, which is available to authorized users.

No abstract

MicroRNAs (miRNAs) play a critical role in cancer development and progression. Aberrant expression of miR-15a has recently been reported in several cancers, but its role in non-small cell lung cancer (NSCLC) still remains obscure. We investigated the effects of miR-15a on proliferation, apoptosis, and metastasis in A549 cells. Eighteen paired NSCLC and adjacent non-tumor lung tissues were surgically removed and immediately snap frozen until total RNA was extracted and confirmed by two independent pathologists. The targets of miR-15a were predicted by bioinformatics tools. RNA isolation and quantitative real-time PCR (qRT-PCR), Western blot analysis, cell proliferation assay, cell cycle analysis, cell apoptosis assay, and migration and invasion assays were done. The wild type (WT) or mutant type (MT) 3'-untranslated region (UTR) vectors were co-transfected with miR-15a or negative control into A549 cells, and after 24 h of transfection, luciferase activity was measured using the Dual-Glo luciferase assay kit. Statistical analysis was performed using SPSS 13.0 software (SPSS, Chicago, IL, USA). P values of less than 0.05 were considered statistically significant. miR-15a was significantly downregulated in NSCLC than in adjacent non-cancerous tissues. miR-15a overexpression remarkably inhibited cell viability, invasion, and migration and promoted the apoptosis of NSCLC cells. Additionally, inhibition of miR-15a expression had the opposite effects on tumor progression, while cell cycle remained unaltered. Furthermore, we identified that BCL2L2 was a target of miR-15a and negatively regulated by miR-15a at the translational level. miR-15a acts as a tumor suppressor in NSCLC by directly targeting BCL2L2 and may serve as a potential diagnostic biomarker and therapeutic target for NSCLC.

No abstract

Lung cancer has the highest mortality rate among cancers; however, its nosogenesis is still unclear. Genome-wide association studies have shown that the telomerase reverse transcriptase (TERT) gene, located in the chromosome 5p15.33 region, is one of the genes associated with the risk of lung cancer. In this case-control study, we genotyped 11 tag single-nucleotide polymorphisms of the TERT gene to evaluate their association with lung cancer risk in the Han Chinese population. Two tag single-nucleotide polymorphisms were found to be associated with lung cancer risk on using the χ2-test: rs4246742 [odds ratio (OR)=0.77, 95% confidence interval (CI) 0.60-0.98; P=0.03] and rs2853672 (OR=1.26, 95% CI 1.01-1.57; P=0.045). By using SNPStats software we also found rs2242652 (OR=1.47, 95% CI 1.02-2.13; P=0.04) in the dominant model and rs2736098 (OR=1.38, 95% CI 1.06-1.80; P=0.017), rs2853672 (OR=1.41, 95% CI 1.11-1.80; P=0.0048), and rs4246742 (OR=0.75, 95% CI 0.58-0.97; P=0.029) in the log-additive model. 'T/C-T/T' of rs10069690 conferred an increased risk for male sex in the dominant model (OR=1.80, 95% CI, 1.05-3.08; P=0.03) and 'TC' increased risk for male sex in the overdominant model (OR=1.85, 95% CI, 1.08-3.17; P=0.031). Our findings, combined with previous studies, suggest that polymorphisms in the TERT gene contribute to the risk for lung cancer in the Chinese Han population.