Survival-associated alternative splicing events interact with the immune microenvironment in stomach adenocarcinoma.

BACKGROUND: Alternative splicing (AS) increases the diversity of mRNA during transcription; it might play a role in alteration of the immune microenvironment, which could influence the development of immunotherapeutic strategies against cancer. AIM: To obtain the transcriptomic and clinical features and AS events in stomach adenocarcinoma (STAD) from the database. The overall survival data associated with AS events were used to construct a signature prognostic model for STAD. METHODS: Differentially expressed immune-related genes were identified between subtypes on the basis of the prognostic model. In STAD, 2042 overall-survival-related AS events were significantly enriched in various pathways and influenced several cellular functions. Furthermore, the network of splicing factors and overall-survival-associated AS events indicated potential regulatory mechanisms underlying the AS events in STAD. RESULTS: An eleven-AS-signature prognostic model (CD44|14986|ES, PPHLN1|21214|AT, RASSF4|11351|ES, KIAA1147|82046|AP, PPP2R5D|76200|ES, LOH12CR1|20507|ES, CDKN3|27569|AP, UBA52|48486|AD, CADPS|65499|AT, SRSF7| 53276|RI, and WEE1|14328|AP) was constructed and significantly related to STAD overall survival, immune cells, and cancer-related pathways. The differentially expressed immune-related genes between the high- and low-risk score groups were significantly enriched in cancer-related pathways. CONCLUSION: This study provided an AS-related prognostic model, potential mechanisms for AS, and alterations in the immune microenvironment (immune cells, genes, and pathways) for future research in STAD.

4,4'­Bond secalonic acid D targets SP cells and inhibits metastasis in hepatocellular carcinoma.

The existence of cancer stem cells (CSCs) is considered to be the main reason for chemoresistance, metastasis and the ultimate failure of treatment in hepatocellular carcinoma (HCC). However, there are a few chemical agents that may inhibit CSCs. The present study identified that 4,4'­bond secalonic acid D (4,4'­SAD), a compound isolated from the marine­derived fungus Penicillium oxalicum, inhibited the growth of side population (SP) cells isolated from human liver cancer cell lines PLC/PRF/5 and HuH­7 by attenuating the expression of ATP­binding cassette superfamily G member 2. Furthermore, the results of wound healing, Transwell, western blotting and reverse transcription­quantitative PCR assays demonstrated that 4,4'­SAD suppressed the invasion and migration of SP cells by downregulating matrix metallopeptidase 9 (MMP­9) and upregulating the antagonist tissue inhibitor of metalloproteinases 1 in vitro. Moreover, in vivo study results found that 4,4'­SAD had anti­lung metastasis efficacy via the decrease of MMP­9 expression in the H22 HCC model of Kunming mice. Therefore, the present study identified the potential of 4,4'­SAD as a promising candidate for the treatment of advanced liver cancer.

Bacillus xiapuensis sp. nov., isolated from marine sediment.

A rod-shaped, endospore-forming, aerobic bacterium, designated FJAT-46582T, was isolated from a sediment sample of the coastal region in Xiapu County, Fujian Province in China. Growth was observed at 10-30 °C (optimum, 25 °C), in 0-7.0 % NaCl (0 %) and at pH 6.0-11.0 (pH 8.0), respectively. The cell-wall peptidoglycan contained meso-diaminopimelic acid and the isoprenoid quinone was MK-7. The main fatty acids were anteiso-C17 : 0 (26.5 %), anteiso-C15 : 0 (19.6 %), iso-C15 : 0 (14.4 %) and C16 : 0 (10.5 %). The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidyl ethanolamine. Phylogenetic analysis based on 16S rRNA gene sequences affiliated strain FJAT-46582T with the genus Bacillus, and showed the highest sequence similarity to Bacillus thermotolerans SGZ-8T (97.6 %) and Bacillus ectoinformans (97.1 %). The average nucleotide identity and in silico DNA-DNA hybridization values between strain FJAT-46582T and the most closely related species were 72.3 and 22.9 %, respectively, which were much lower than the thresholds commonly used to define species (96 and 70 %, respectively) indicating that it belonged to a different taxon. The DNA G+C content was 44.2 mol%. The phenotypic characters and taxono-genomics study revealed that strain FJAT-46582T represents a novel Bacillus species, for which the name Bacillus xiapuensis sp. nov. is proposed. The type strain is FJAT-46582T (=JCM 33155=CCTCC AB 2017047T).

Isolation of 4,4'-bond secalonic acid D from the marine-derived fungus Penicillium oxalicum with inhibitory property against hepatocellular carcinoma.

4,4'-bond secalonic acid D (4,4'-SAD) is a known compound isolated from the marine-derived fungus Penicillium oxalicum. No study about the antitumor effect of this compound has been reported, except for a few focusing on its bactericidal properties. Herein, we performed an in vitro biology test and found that 4,4'-SAD stimulated the apoptosis of tumor cells in the human hepatocellular carcinoma cell lines PLC/PRF/5 and HuH-7 by activating caspase-3, caspase-8, caspase-9, PARP, p53, and cyclin B1, as well as by regulating the Bax/Bcl-2 ratio. In vivo studies showed that 4,4'-SAD had antitumor efficacy in H22 cell xenograft model. Immunohistochemical analysis revealed that 4,4'-SAD could regulate Bax expression, which is a biomarker of tumor growth. In summary, 4,4'-SAD significantly inhibited tumor growth both in vivo and in vitro.

Bacillus praedii sp. nov., isolated from purplish paddy soil.

A Gram-stain-positive, rod-shaped, endospore-forming, aerobic bacterium, designated strain FJAT-25547T, was isolated from the purplish paddy soil collected from Linshan Township, Yanting Prefecture of Sichuan Province in PR China (31° 16' N 105° 27' E). Growth was achieved aerobically at temperatures between 15 and 40 °C (optimum 30 °C), with between 0 and 10.0 % NaCl (w/v) (optimum 4 %) and in the range of pH 5.0-12.0 (optimum pH 9.0). The cell-wall peptidoglycan contained meso-diaminopimelic acid, and the main isoprenoid quinone was MK-7. The major fatty acids were iso-C15 : 0 (55.4 %), anteiso-C15 : 0 (22.2 %), iso-C16 : 0 (5.1 %) and iso-C14 : 0 (6.5 %). The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain FJAT-25547T was a member of the genus Bacillus and was most closely related to Bacillus horneckiae DSM 23495T (97.7 % similarity), Bacillus eiseniae A1-2T (97.5 %), Bacillus mesophilum IITR-54T (97.2 %) and Bacillus kochii WCC 4582T (97.0 %). The average nucleotide identity value between strain FJAT-25547T and the type strain of the most closely related species, B. horneckiae DSM 23495T, was 77.7 %, less than the proposed cut-off value of 96.0 % for differentiating species within the genus. The in silico DNA-DNA hybridization value of strain FJAT-25547T with the most closely related species was 22.7 %, <70 %, again indicating they belong to different taxa. The DNA G+C content of strain FJAT-25547T was 39.1 mol%. This taxono-genomics study revealed that strain FJAT-25547T represents a novel species of the genus Bacillus for which the name Bacillus praedii sp. nov. (type strain FJAT-25547T=CCTCC AB 2015208T=DSM 101002T) is proposed.

Antitumor Effects and Related Mechanisms of Penicitrinine A, a Novel Alkaloid with a Unique Spiro Skeleton from the Marine Fungus Penicillium citrinum.

Penicitrinine A, a novel alkaloid with a unique spiro skeleton, was isolated from a marine-derived fungus Penicillium citrinum. In this study, the isolation, structure and biosynthetic pathway elucidation of the new compound were described. This new compound showed anti-proliferative activity on multiple tumor types. Among them, the human malignant melanoma cell A-375 was confirmed to be the most sensitive. Morphologic evaluation, apoptosis rate analysis, Western blot and real-time quantitative PCR (RT-qPCR) results showed penicitrinine A could significantly induce A-375 cell apoptosis by decreasing the expression of Bcl-2 and increasing the expression of Bax. Moreover, we investigated the anti-metastatic effects of penicitrinine A in A-375 cells by wound healing assay, trans-well assay, Western blot and RT-qPCR. The results showed penicitrinine A significantly suppressed metastatic activity of A-375 cells by regulating the expression of MMP-9 and its specific inhibitor TIMP-1. These findings suggested that penicitrinine A might serve as a potential antitumor agent, which could inhibit the proliferation and metastasis of tumor cells.

Speradines F-H, three new oxindole alkaloids from the marine-derived fungus Aspergillus oryzae.

A rare hexacyclic oxindole alkaloid, speradine F (1), together with two novel tetracyclic oxindole alkaloids, speradines G (2) and H (3), were isolated from the marine-derived fungus Aspergillus oryzae. Their structures were determined by spectroscopic methods and X-ray diffraction analysis. This study is the first report on cyclopiazonic acid (CPA)-type alkaloids with a hexacyclic skeleton.

The marine fungal metabolite, dicitrinone B, induces A375 cell apoptosis through the ROS-related caspase pathway.

Dicitrinone B, a rare carbon-bridged citrinin dimer, was isolated from the marine-derived fungus, Penicillium citrinum. It was reported to have antitumor effects on tumor cells previously; however, the details of the mechanism remain unclear. In this study, we found that dicitrinone B inhibited the proliferation of multiple tumor types. Among them, the human malignant melanoma cell, A375, was confirmed to be the most sensitive. Morphologic evaluation, cell cycle arrest and apoptosis rate analysis results showed that dicitrinone B significantly induced A375 cell apoptosis. Subsequent observation of reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) reduction revealed that the apoptosis induced by dicitrinone B may be triggered by over-producing ROS. Further studies indicated that the apoptosis was associated with both intrinsic and extrinsic apoptosis pathways under the regulation of Bcl-2 family proteins. Caspase-9, caspase-8 and caspase-3 were activated during the process, leading to PARP cleavage. The pan-caspase inhibitor, Z-VAD-FMK, could reverse dicitrinone B-induced apoptosis, suggesting that it is a caspase-dependent pathway. Our data for the first time showed that dicitrinone B inhibits the proliferation of tumor cells by inducing cell apoptosis. Moreover, compared with the first-line chemotherapy drug, 5-fluorouracil (5-Fu), dicitrinone B showed much more potent anticancer efficacy, suggesting that it might serve as a potential antitumor agent.

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry.

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu2+ as template. The cavity in NCM-PVA-I-I matched Cu2+ very well and the selectivity was high. Cu2+ entered the cavity and then could form ionic association ([Cu2+] x [(Fin-)2]) with the anion of fluorescein (Fin-) outside the cavity by electrostatic effect. [Cu2+] x [(Fin-)2] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its DeltaI(p) was proportional to the content of Cu2+. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00-144.00 fg Cu2+ spot(-1) (sample volume: 0.40 microL spot(-1), corresponding concentration: 5.00-360.00 pg mL(-1)), and the detection limit calculated by 3Sb/k was 0.43 fg Cu2+ spot(-1) (corresponding concentration: 1.1 x 10(-12) g mL(-1), n=11). Samples containing 2.00 and 144.00 fg Cu2+spot(-1) were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples.

Remarkably high activities of testicular cytochrome c in destroying reactive oxygen species and in triggering apoptosis.

Hydrogen peroxide (H(2)O(2)) is the major reactive oxygen species (ROS) produced in sperm. High concentrations of H(2)O(2) in sperm induce nuclear DNA fragmentation and lipid peroxidation and result in cell death. The respiratory chain of the mitochondrion is one of the most productive ROS generating systems in sperm, and thus the destruction of ROS in mitochondria is critical for the cell. It was recently reported that H(2)O(2) generated by the respiratory chain of the mitochondrion can be efficiently destroyed by the cytochrome c-mediated electron-leak pathway where the electron of ferrocytochrome c migrates directly to H(2)O(2) instead of to cytochrome c oxidase. In our studies, we found that mouse testis-specific cytochrome c (T-Cc) can catalyze the reduction of H(2)O(2) three times faster than its counterpart in somatic cells (S-Cc) and that the T-Cc heme has the greater resistance to being degraded by H(2)O(2). Together, these findings strongly imply that T-Cc can protect sperm from the damages caused by H(2)O(2). Moreover, the apoptotic activity of T-Cc is three to five times greater than that of S-Cc in a well established apoptosis measurement system using Xenopus egg extract. The dramatically stronger apoptotic activity of T-Cc might be important for the suicide of male germ cells, considered a physiological mechanism that regulates the number of sperm produced and eliminates those with damaged DNA. Thus, it is very likely that T-Cc has evolved to guarantee the biological integrity of sperm produced in mammalian testis.