[Overexpression of miR-431-5p impairs mitochondrial function and induces apoptosis in gastric cancer cells via the Bax/Bcl-2/caspase3 pathway]

OBJECTIVE

To investigate the expression of microRNA miR-431-5p in gastric cancer (GC) tissues and its effects on apoptosis and mitochondrial function in GC cells.

METHODS

The expression level of miR-431-5p in 50 clinical samples of GC tissues and paired adjacent tissues was detected using real-time fluorescence quantitative PCR, and its correlation with the clinicopathological features of the patients was analyzed. A cultured human GC cell line (MKN-45 cells) were transfected with a miR-431-5p mimic or a negative control sequence, and the cell proliferation, apoptosis, mitochondrial number, mitochondrial potential, mitochondrial permeability transition pore (mPTP), reactive oxygen species (ROS) production and adenosine triphosphate (ATP) content were detected using CCK-8 assay, flow cytometry, fluorescent probe label, or ATP detection kit. The changes in the expression levels of the apoptotic proteins in the cells were detected with Western blotting.

RESULTS

The expression level of miR-431-5p was significantly lower in GC tissues than in the adjacent tissues (P < 0.001) and was significantly correlated with tumor differentiation (P=0.0227), T stage (P=0.0184), N stage (P=0.0005), TNM stage (P=0.0414) and vascular invasion (P=0.0107). In MKN-45 cells, overexpression of miR-431-5p obviously inhibited cell proliferation and induced cell apoptosis, causing also mitochondrial function impairment as shown by reduced mitochondrial number, lowered mitochondrial potential, increased mPTP opening, increased ROS production and reduced ATP content. Overexpression of miR-431-5p significantly downregulated the expression of Bcl-2 and increased the expressions of pro-apoptotic proteins p53, Bcl-2 and cleaved caspase-3 protein.

CONCLUSION

The expression of miR-431-5p is down-regulated in GC, which results in mitochondrial function impairment and promotes cell apoptosis by activating the Bax/Bcl-2/caspase3 signaling pathway, suggesting the potential role of miR-431-5p in targeted therapy for GC.

Annulohypoxylon sp. FPYF3050 produces volatile organic compounds against the pine wood nematode, Bursaphelenchus xylophilus

Natural volatiles released by the fungus, Annulohypoxylon sp. FPYF3050, were evaluated against the pine wood nematode (PWN), Bursaphelenchus xylophilus. Our results showed that volatile organic compounds (VOCs) caused 64.1 and 58.4% mortality of second-stage juveniles (J2) and mixed-stages (eggs, J2, third- and fourth-stage juveniles, and adults) of populations of PWN, but no inhibitive effects were detected on nematode eggs in the experiment. Analysis of the gases within the Petri plate by gas chromatography-mass spectrometry (GC-MS) showed a yield of an unique volatile with dominant 1,8-cineole in 77.4% relative area (RA) after 72 h treatment of nematodes with Annulohypoxylon sp. FPYF3050 and Botrytis cinerea. The commercial 1,8-cineole at concentrations of 2, 5, 10 and 15 μl ml−1 was applied to examine nematicidal activity. The results showed that 1,8-cineole had a 40-100% inhibition on the nematode eggs during 48 h treatment, more than 82.9% mortality of J2 after 24 h, 48 h and 96 h, and 18.7-91.9% mortality of the mixed-stage population, depending on the period after exposure. This result indicates that 1,8-cineole in the volatile gas emissions of Annulohypoxylon sp. FPYF3050 may play a crucial inhibitory effect on the pine wood nematode The nematicidal volatile gas from fungi may provide a useful biocontrol agent for controlling B. xylophilus.

An Endophytic Diaporthe apiculatum Produces Monoterpenes with Inhibitory Activity against Phytopathogenic Fungi

Volatile organic compounds (VOCs) from endophytic fungi are becoming a potential antibiotic resource. The inhibitive effects of VOCs produced by an endophytic fungus in Leucaena leucocephala were investigated on plant pathogens in this study. Using standard morphological methods and multigene phylogeny, the fungus was identified as Diaporthe apiculatum strain FPYF 3052. Utilizing a two- compartment Petri plate bioassay method, the VOCs from this fungus showed bioactivity ranging from 23.8% to 66.7% inhibition on eight plant pathogens within 24 hours. The SPME-GC/MS technique identified fifteen volatile compounds with dominant terpenoids γ-terpinene (39.8%), α-terpinene (17.2%), and (-)-4-terpineol (8.4%) from the VOCs. Commercial α-terpinene, γ-terpinene, and (-)-4-terpineol demonstrated inhibition on the tested pathogens at concentrations from 0.2 to 1.0 µl/ml within 72 h in the bioassay system. The inhibition rates were from 28% to 100% percent using 1.0 µl/ml within 48 h. (-)-4-Terpineol was the most active of the terpenoids causing up to 100% inhibition. The data illustrate that these monoterpenes play an important role in the inhibitive bioactivity of the VOCs of D. apiculatum FPYF 3052. Most importantly, (-)-4-terpineol is now for the first time, reported to have capability of strong antifungal activity and could be developed as an antibiotic substance.

Identification and characterization of Populus microRNAs in response to plant growth-promoting endophytic Streptomyces sp. SSD49

Endophytic Streptomyces sp. SSD49 inhibited eight pathogens, including the human opportunistic pathogenic microorganisms, the plant pathogenic fungi and bacteria. The growth of soybeans, tomatoes, peppers and Populus tomentosa seedings inoculated with SSD49 are remarkably promoted. Here, we constructed two P. tomentosa seedling microRNA (miRNA) libraries inoculated with (PS30d) and without SSD49 (PC30d) to explore the molecular regulatory roles in the plant response to the beneficial bacteria. Totals of 314 known and 144 novel miRNAs were identified, among which 27 known and 11 novel miRNA had significantly different expression. The targets of up-regulated miR160, miR156, ptc114 and down-regulated miR319 and other differential expressed miRNAs primarily regulated genes encoding transcription factors (auxin response factor, small auxin-up RNA, and GRAS proteins), disease resistance proteins, phytohormone oxidase, and response regulators, which could promote plant growth, influence disease resistance and miRNA biosynthesis in P. tomentosa. This is the first report on the genome-wide identification of biocontrol endophytic Streptomyces inoculation-responsive miRNAs using small RNA sequencing in P. tomentosa and these findings provide new insight into understanding the biocontrol effects of endophytic Streptomyces.

Antifungal Activities of Volatile Secondary Metabolites of Four Diaporthe Strains Isolated from Catharanthus roseus

Four endophytic fungi were isolated from the medicinal plant, Catharanthus roseus, and were identified as Diaporthe spp. with partial translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB), histone H3 (HIS), calmodulin (CAL) genes, and rDNA internal transcribed spacer (ITS) region (TEF1-TUB-HIS--CAL-ITS) multigene phylogeny suggested for species delimitation in the Diaporthe genus. Each fungus produces a unique mixture of volatile organic compounds (VOCs) with an abundant mixture of terpenoids analyzed by headspace solid-phase microextraction (SPME) fiber-GC/MS. These tentatively-detected terpenes included α-muurolene, β-phellandrene, γ-terpinene, and α-thujene, as well as other minor terpenoids, including caryophyllene, patchoulene, cedrene, 2-carene, and thujone. The volatile metabolites of each isolate showed antifungal properties against a wide range of plant pathogenic test fungi and oomycetes, including Alternaria alternata, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium graminearum, and Phytophthora cinnamomi. The growth inhibition of the pathogens varied between 10% and 60% within 72 h of exposure. To our knowledge, the endophytic Diaporthe-like strains are first reported from Catharanthus roseus. VOCs produced by each strain of the endophytic Diaporthe fungi were unique components with dominant monoterpenes comparing to known Diaporthe fungal VOCs. A discussion is presented on the inhibitive bioactivities of secondary metabolites among endophytic Diaporthe fungi and this medicinal plant.

Phase I study of chidamide (CS055/HBI-8000), a novel histone deacetylase inhibitor, in patients with advanced solid tumors and lymphomas

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Background: Chidamide (CS055/HBI-8000) is a new benzamide type of histone deacetylase (HDAC) inhibitor with low nanomolar activity against HDAC1, 2, 3 and 10. This Phase I study evaluated the safety and tolerability of chidamide in patients (pts) with advanced solid tumors and lymphomas. Methods: 31 pts with refractory or relapsed advanced solid tumors (22) and lymphomas (9) were enrolled in this study. Escalating doses of 5, 10, 17.5, 25, 32.5 and 50 mg Chidamide (each with 3 to 7 pts) were administered orally either twice or three times per week for 4 consecutive weeks every 6 weeks. Results: No dose limiting toxicities (DLTs) were identified in the 2 x per week cohorts (22 pts) up to 50 mg; G2 and G3 hematological toxicities (leukopenia/neutropenia and thrombocytopenia) were observed at 50 mg. DLTs were reported as G3 diarrhea or vomiting in 2 pts in the 3 x per week cohort at 50 mg. Common adverse events were G1/G2, fatigue (n = 11), thrombocytopenia (n = 9), anorexia (n = 8), nausea/vomiting (n = 7), leukopenia/neutropenia (n = 6), hypochromia (n = 6), and diarrhea (n = 5). No cystitis, pericarditis, pericardial effusion or prolonged QTc intervals were observed. Single dose PK analysis in pts with 25, 32.5 and 50 mg revealed T1/2 of 16.8–18.3 h, Tmax of 1–2 h in most cases, and a dose-related increase in Cmax and AUC. Multiple dose PK analysis in pts with 32.5 mg 3 x per week suggested drug accumulation with this regimen. Significant induction of histone (H3) acetylation was observed in peripheral white blood cells, which lasted for 2–3 days in most pts after single dosing. 25 pts with total treatment cycles of 49 (range 1–6) were evaluable for efficacy. 4 pts with T-cell lymphomas (4/5 evaluable) and 1 pt with submandibular adenoid cystic carcinoma achieved PR, and 11 pts (2 B-cell lymphomas and 9 solid tumors) experienced SD. Conclusions: Chidamide was well-tolerated in pts with advanced solid tumors and lymphomas in the tested regimens. In addition, the compound exhibited a relatively long half-life, a long-lasting biomarker response and encouraging antitumor activity at well-tolerated doses. The overall phase I results recommend the 2 x per week regimen for phase II studies.

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[Investigation on primary vectors of Borrelia burgdorferi in China]

From 1987 to 1997, primary vectors of borrelia burgdorferi sensu lato (B.b.s.l.) were investigated in China. A total number of 17,000 ticks collected from 20 provinces, city and autonomous region were classified, including 2 families 8 genus 23 species. There were 108 isolates of B.b.s.l. discovered from 8 species of ticks, including Ixodes persulcatus, I. granulatus, I. acutitarsus, Haemaphysalis concinna, H. longicornis, H. bispinosis, H. cornigera taiwana and Dermacentor silvarum. Ixodes persulcatus was found as the dominant species, accounted for more than 80% of the total number of collected ticks. 20 to 45 per cent adult Ixodes persulcatus contained spirochetes as determined by direct immunofluorescence in the northeast and northwest areas. Seasonal change of adult Ixodes persulcatus was coincident with patients with erythema chronicum migrans. These studies proved that Ixodes persulcatus played a leading role in the transmission of B.b.s.l. to human being in northern region of China. Haemaphysalis bispinosis and Ixodes granulatus were identified as the dominant species with 16 to 40 per cent adult Haemaphysalis bispinosis and 24% per cent adult Ixodes granulatus containing spirochetes as determined by direct immunofluorescence in the southern region of China. Haemaphysalis bispinosis and Ixodes granulatus were proved to be important vectors of B.b.s.l. in the southern area of China.