Discovering a New Okadaic Acid Derivative, a Potent HIV Latency Reversing Agent from Prorocentrum lima PL11: Isolation, Structural Modification, and Mechanistic Study.

Marine toxins (MTs) are a group of structurally complex natural products with unique toxicological and pharmacological activities. In the present study, two common shellfish toxins, okadaic acid (OA) (1) and OA methyl ester (2), were isolated from the cultured microalgae strain Prorocentrum lima PL11. OA can significantly activate the latent HIV but has severe toxicity. To obtain more tolerable and potent latency reversing agents (LRAs), we conducted the structural modification of OA by esterification, yielding one known compound (3) and four new derivatives (4-7). Flow cytometry-based HIV latency reversal activity screening showed that compound 7 possessed a stronger activity (EC50 = 46 ± 13.5 nM) but was less cytotoxic than OA. The preliminary structure-activity relationships (SARs) indicated that the carboxyl group in OA was essential for activity, while the esterification of carboxyl or free hydroxyls were beneficial for reducing cytotoxicity. A mechanistic study revealed that compound 7 promotes the dissociation of P-TEFb from the 7SK snRNP complex to reactivate latent HIV-1. Our study provides significant clues for OA-based HIV LRA discovery.

Homo/Hetero-Dimers of Aromatic Bisabolane Sesquiterpenoids with Neuroprotective Activity from the Fungus Aspergillus versicolor A18 from South China Sea

Chromatographic fractionation of the EtOH extracts of the marine-derived fungus Aspergillus versicolor A18 has led to the isolation of 11 homo/hetero-dimers of aromatic bisabolane sesquiterpenoids including eight diphenyl ether-coupled aromatic bisabolanes (1a/1b and 5−10) and three homodimers (2−4), together with their monomers including three aromatic bisabolanes (11−13) and two diphenyl ethers (14 and 15). Their structures and absolute configurations were elucidated by extensive spectroscopic analysis including HRESIMS, 1D/2D NMR, calculated ECD, and the optical rotatory data. Among the four new compounds, (+/−)-asperbisabol A (1a/1b), asperbisabol B (2), and asperbisabol C (3), the enantiomers 1a and 1b represent an unprecedented skeleton of diphenyl ether-coupled aromatic bisabolane sesquiterpenoids with a spiroketal core moiety. The neuroprotective effects of selected compounds against sodium nitroprusside (SNP)-induced injury were evaluated in PC12 cells by the MTT assay. Five compounds (1a, 6, and 8−10) showed remarkable neuroprotective activities at 10 µM, being more active than the positive control edaravone.

Identification of a novel germ cell marker MnTdrd from the oriental river prawn Macrobrachium nipponense.

Germ cell-specific genes play an important role in establishing the reproductive system in sexual organisms and have been used as valuable markers for studying gametogenesis and sex differentiation. Previously, we isolated a vasa transcript as a germ cell marker to trace the origin and migration of germ cells in the oriental river prawn Macrobrachium nipponense. Here, we identified a new germ cell-specific marker MnTdrd RNA and assessed its temporal and spatial expression during oogenesis and embryogenesis. MnTdrd transcripts were expressed in high abundance in unfertilized eggs and embryos at cleavage stage and then dropped significantly during late embryogenesis, suggesting that MnTdrd mRNA is maternally inherited. In situ hybridization of ovarian tissue showed that MnTdrd mRNA was initially present in the cytoplasm of previtellogenic oocyte and localized to the perinuclear region as the accumulation of yolk in vitellogenic oocyte. Whole-mount in situ hybridization of embryos showed that MnTdrd-positive signals were only localized in one blastomere until 16-cell stage. In the blastula, there were approximately 16 MnTdrd-positive blastomeres. During embryonized-zoea stage, the MnTdrd-positive cells aggregated as a cluster and migrated to the genital rudiment which would develop into primordial germ cells (PGCs). The localized expression pattern of MnTdrd transcripts resembled that of the previously identified germ cell marker vasa, supporting the preformation mode of germ cell specification. Therefore, we concluded that MnTdrd, together with vasa, is a component of the germ plasm and might have critical roles in germ cell formation and differentiation in the prawn. Thus, MnTdrd can be used as a novel germ cell marker to trace the origin and migration of germ cells.

Germ plasm and the origin of the primordial germ cells in the oriental river prawn Macrobrachium nipponense.

Germ plasm is a special cytoplasmic component containing special RNAs and proteins, and is located in specific regions of oocytes and embryos. Only the blastomeres inheriting the germ plasm can develop into primordial germ cells (PGCs). By using Vasa mRNA as a germline marker, we previously demonstrated that germline specification followed the preformation mode in the prawn Macrobrachium nipponense. In this study, we raised the Vasa antibody to identify germ plasm in the oocyte and trace the origin and migration of PGCs. In previtellogenic oocytes, Vasa protein was detected in the perinuclear region, in which electron-dense granules associated with numerous mitochondria were mostly visualized under a transmission electron microscope. In mature oocytes, immunosignal was localized to a large granule under the plasma membrane. During early embryogenesis, the granule was inherited by a single blastomere from 1-cell to 16-cell stages, and thereafter was segregated into two daughter blastomeres at the 32-cell stage. In gastrula, the Vasa-positive cells were large with typical PGC characteristics, containing a big round nucleus and a prominent nucleolus. The immunosignal was localized to the perinuclear region again. In the zoea stage, the Vasa-positive cells migrated toward the genital ridge and clustered in the dorsomedial region close to the yolk portion. Accordingly, we concluded that the prawn PGCs could be specified from the 16-cell stage by inheriting the germplasm. To our knowledge, this is the first report on the identification of the prawn germ plasm and PGCs. The continuous expression of Vasa protein throughout oogenesis and embryogenesis suggests that Vasa protein could be an important factor in germ plasm that functions in early germ cell specification.

Highly Tunable Electronic Structures of Phosphorene/Carbon Nanotube Heterostructures through External Electric Field and Atomic Intercalation.

Black phosphorene (BP)/carbon nanotube (CNT) heterostructures can be classified as either type I or II, depending on the size of the CNTs. An external electric field (Eext) can modulate the interfacial electronic structures and separate the electron and hole carriers of the BP/CNT heterostructures. The giant Stark effect is observed, and the band gap of the semiconducting heterostructures can vary several-fold. The intercalation of 3d transition metals can strongly bond BP and CNTs together. Furthermore, strong ferromagnetism with Curie temperature (TC) above room temperature is predicted. It is expected that these BP/CNT heterostructures will provide new opportunities and applications in the fields of optoelectronics and electronics as well as spintronics.

Efficient Split-Lanczos propagator for strong-field ionization of atoms.

High angular momentum partial waves are indispensable in the numerical calculations of the time-dependent Schrödinger equation (TDSE) for the interaction between atoms and strong long-wavelength laser pulses. In these cases, the widely-applied Lanczos propagator, used to solve the TDSE, requires an extremely small time step to be convergent. By splitting out the centrifugal potential from the whole Hamiltonian, we demonstrate that the stiffness of the TDSE can be reduced and a rather large time step is allowed for the present Split-Lanczos propagator. Compared with the ordinary Lanczos propagator, the efficiency of the propagation can be improved by more than 100 times for large angular momentum in present tests.

Unusual Cytotoxic Steroidal Saponins from the Gorgonian Astrogorgia dumbea.

Three steroidal saponins, including astrogorgiosides A (1) and B (2) bearing acetamido-glucose moieties, and astrogorgioside C (3) with a 19-nor and bearing an aromatized B ring steroid aglycone, together with a known major saponin dimorphoside A (4), were obtained from the gorgonian Astrogorgia dumbea collected near Dongshan Island in East China Sea. Structures of these compounds were elucidated by in-depth spectral and chemical methods, including 2D-NMR, HR-ESI-MS spectra, and acidic hydrolysis. For the first time, acetamido-glucose moiety is being reported from a gorgonian. The B-ring aromatized steroid aglycone of compound 3 is also rare in marine natural products. Compounds 1-3 exhibited moderate cytotoxic activity with IC50 values of 26.8-45.6 µM against human tumor cells Bel-7402 and K562.

Inhibition of mTOR signalling potentiates the effects of trichostatin A in human gastric cancer cell lines by promoting histone acetylation.

Deregulation of the mammalian target of rapamycin pathway (mTOR pathway) is associated with human cancer. The relationship between mTOR pathway and histone acetylation is still unclear in gastric cancer (GC). Immunohistochemistry was used to examine the phosphorylation of mTOR and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) in GC tissues. MKN45 and SGC7901 cells were treated with the mTOR inhibitor rapamycin (RAPA) alone or in combination with the phosphatidylinositol 3-kinase inhibitor LY294002 and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). Small interfering RNA (siRNA) technology was also used to knockdown mTOR. Phosphorylated mTOR and phosphorylated 4E-BP1 were expressed in 71.1% and 68.4% of the human GC tissues tested, respectively; significantly higher than the levels in para-cancerous tissues (50% and 57.9%) and normal tissues (44.6% and 29%). RAPA markedly inhibited cell proliferation, induced G1 cell cycle arrest, and reduced phosphorylation of p70 S6 protein kinase (p70S6K) and 4E-BP1 in GC cells, particularly when used in combination with LY294002 or TSA. The mRNA expression of the tumour suppressor gene p21(WAF1) increased significantly in GC cells treated with both RAPA and TSA. Histone acetylation also increased after RAPA and TSA treatment or siRNA knockdown of mTOR. Our findings suggest that the mTOR pathway is activated in GC, and also that inhibition of mTOR enhances the ability of TSA to suppress cell proliferation and lead to cell cycle arrest via increasing histone acetylation and p21(WAF1) transcription in human MKN45 and SGC7901 GC cells.

[Purine and carboline alkaloids from ascidian Symplegma oceania].

Five purine and carboline alkaloids were isolated from the methanol extract of the ascidian Symplegma oceania. Classic chromatographies including preparative HPLC were used for isolation and purification of the compounds. The structures were established as 6-methoxy-7-methyl-8-oxoguanine (1), 2-methylimino-3-methyl-6-methylamino- 9H-purine (2), 1,2,3,4-tetrahydro-betacarboline (3), 1,2,3,4-tetrahydro-1-methyl-beta-carboline (4) and 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (5) by comparison the spectroscopic data (MS, 1H, 13C-NMR) with those reported in the literatures. Compounds 2-5 were reported from the the genus Symplegma for the first time. The purine and carboline were the major alkaloid types of S. oceania.

Eosinophilic gastroenteritis with abdominal pain and ascites: A case report.

BACKGROUND: Eosinophilic gastroenteritis (EGE) is a rare disease that presents many unspecific gastroenterological symptoms. The disease includes three types depending on the depth of eosinophil infiltration in the gastrointestinal tract. The serosal type is the most rare, presenting as ascites. CASE SUMMARY: A 34-year-old man presented with abdominal pain, diarrhea without bloody stool, or nausea. Laboratory test results revealed a peripheral blood eosinophil count (4.85 × 109/L), which was remarkedly elevated. Computed tomography scan demonstrated extensive intestinal wall edema thickening in the duodenum, jejunum, ascending colon and transverse colon; multiple exudative effusion surrounding the intestinal tract, and ascites in the abdominal cavity. A series of examinations excluded eosinophil elevation in secondary diseases. Endoscopic multipoint biopsy detected eosinophilic infiltration in the mucous layer of the transverse colon, with ≥ 50 eosinophils/high power field. All symptoms vanished after a few days of steroid therapy and ascites disappeared within 2 wk. CONCLUSION: EGE should be considered in patients with abdominal pain, ascites, and eosinophilia. Multiple point biopsies are essential for diagnosis.

Hexagonal layered group IV-VI semiconductors and derivatives: fresh blood of the 2D family.

New phases of group IV-VI semiconductors in 2D hexagonal structures are predicted and their unusual physical properties are revealed. The structures of monolayer group IV-VI semiconductors are similar to those of blue phosphorene and each unit has the same ten valence electrons. The band gap of 2D hexagonal group IV-VI semiconductors depends on both the thickness and stacking order. Atomic functionalization can induce ferromagnetism, and the Curie temperature can be tuned. Gapped Dirac fermions with zero mass are developed and this makes it exceed that of graphene. The Fermi velocity can be compared to or even above that of graphene.

Draft Genome Sequences of Nine Cultivable Heterotrophic Proteobacteria Isolated from Phycosphere Microbiota of Toxic Alexandrium catenella LZT09.

Microscopic interactions between phycosphere microbiota and host algae play crucial roles in aquatic ecosystems. Despite their significance, there is a scarcity of available genome sequences derived from the phycosphere microbiome. Here, we report the draft genome sequences of nine heterotrophic proteobacterial strains isolated from the toxic dinoflagellate Alexandrium catenella LZT09 during execution of our Phycosphere Microbiome Project. Further exploration of the genomic features of the alga-associated bacterial community will profoundly help in deeply deciphering the processes and mechanisms governing the host-microbe interactome within algal holobionts in the ocean.

mTOR signaling pathway is a target for the treatment of colorectal cancer.

BACKGROUND: mTOR signaling has been suggested to be an important factor involved in tumorigenesis, but its role in human colorectal cancer (CRC) has not been completely elucidated. Herein, the purpose of this study was to analyze the distribution pattern of mTOR signaling components in CRC and adenoma and to determine whether targeted inhibition of mTOR could be a potential therapeutic strategy for CRC. METHODS: Immunohistochemical analysis was performed on human CRC and adenoma for mTOR signaling components, including mTOR, p70s6 K, and 4EBP1. HCT116 and SW480 human CRC cell lines were treated with siRNA directed against mTOR, and cell viability, cell cycle, and apoptosis were assessed. HCT116 and SW480 cells were injected into athymic nude mice to establish a CRC xenograft model. Mice were randomly transfected with either nontargeting control or mTOR siRNA, and tumor volume, mTOR signaling activity, and apoptosis were evaluated. RESULTS: mTOR signaling components, including mTOR, p70s6 K, and 4EBP1, were highly activated in glandular elements of CRC and colorectal adenomas with high-grade intraepithelial neoplasia (HIN), with a correlation between staining intensity and depth of infiltration in CRC. Inhibition of mTOR expression using a specific mTOR siRNA resulted in considerably decreased in vitro and in vivo cell growth. CONCLUSIONS: mTOR signaling is associated with the clinical pathological parameters of human CRC. siRNA-mediated gene silencing of mTOR may be a novel therapeutic strategy for CRC.

Combined inhibition of MEK and mTOR signaling inhibits initiation and progression of colorectal cancer.

The role of the mTOR signal pathway in colorectal cancer (CRC) pathogenesis remains unclear, and the combination effect of PD98059 (an inhibitor for MEK) and rapamycin (an inhibitor for mTOR) on CRC is still unknown. Here, we found that combination treatment with PD98059 and rapamycin suppressed the proliferation of CRC cells, induced apoptosis, arrested cell cycle, and reduced the incidence and volume of CRC in mice, as well as inhibited phosphorylation of mTOR and the MEK signal pathway components, of which the effects were more significant than single-drug treatments. These findings indicate that PD98059 combined with rapamycin appears to be a promising strategy for inhibiting the initiation, and progression of CRC, which may provide a novel strategy for CRC prevention.

Epigenetic silencing of LRRC3B in colorectal cancer.

OBJECTIVE: Tumor suppressor gene silencing via promoter hypermethylation is an important event in the pathogenesis of colorectal cancer (CRC). Some aberrant DNA hypermethylation has high tumor specificity, so it may contribute to early diagnosis of CRC. The objective of this study was to establish novel therapeutic and diagnostic strategies against CRC by identifying the novel methylation-related genes. MATERIAL AND METHODS: Two microarray-based approaches were used to identify novel methylation-related genes in CRC. We identified methylation-sensitive genes in colon cancer cell line SW1116 by comparing differential expression genes after treatment with the methylation inhibiting drug, 5-aza-2'-deoxycytidine (5-aza-dC) using gene expression microarray. Promoter microarray analysis was performed to identify cancer-specific, methylation-related genes in two patients with CRC. Gene promoter methylation was identified by methylation-specific polymerase chain reaction (PCR) (MSP) in primary CRC. Gene expression level was assessed using real-time PCR analysis. RESULTS: By using gene expression microarray, up-regulation of 253 genes was detected in the CRC cell line, SW1116, after treatment with 5-aza-dC. Of the 253 genes identified by gene expression microarray analysis, LRRC3B (leucine-rich repeat containing 3B) was isolated as a potential methylation-specific gene by promoter microarray analysis. MSP analysis showed frequent methylation of LRRC3B in primary CRC (24/31 cases, 77%). In addition, the LRRC3B methylation intensity was significantly higher in cancer tissues than in the corresponding non-cancerous tissues. Decreased LRRC3B expression (17/31, 55%) was observed in the cancer tissues by real-time PCR. CONCLUSIONS: LRRC3B may be a novel methylation-sensitive tumor suppressor gene in CRC. LRRC3B methylation has significant tumor specificity and may be a biomarker of CRC.

Combined inhibition of Dnmt and mTOR signaling inhibits formation and growth of colorectal cancer.

BACKGROUND AND AIMS: Although the anticancer effects of rapamycin (RPM) and 5-aza-deoxycytidine (AZA) have been studied extensively, the combined effect of these two drugs on colorectal cancer (CRC) is still unknown. This study addresses the effect of AZA and RPM combination therapy on CRC and its influence on the mammalian target of rapamycin (mTOR) and its signal transduction pathway. SUBJECTS AND METHODS: Human CRC cell line HCT116 was treated with AZA alone, RPM alone, or concurrently with a combination of both drugs. Cell viability, apoptosis, and cell cycle distribution were analyzed. CRC was initiated in S-ICR mice, which were then treated with the drugs mentioned above, and tumor incidence and volume were measured. The activity of the mTOR signal transduction pathway was detected by Western blot analysis or immunohistochemistry. RESULTS: Combination treatment with AZA and RPM inhibited the growth of HCT116 cells, induced apoptosis, arrested the cell cycle, and reduced the incidence and tumor volume of CRC in mice, as well as inhibited the phosphorylation of components of the mTOR signal transduction pathway. These effects were more significant than those of single-drug treatments. CONCLUSION: Combination treatment with AZA and RPM inhibits the formation and growth of CRC. These findings may provide a novel strategy for CRC treatment.

[Microarray-based methods to identify DNA methylation in cancer].

DNA methylation is an epigenetic modification associated with gene transcription regulation, X-chromosome inactivation, regulation of development and cell differentiation. Aberrant DNA methylation has been linked to cancer. The advent of microarray technology has provided new opportunities for high-throughput study on DNA methylation. Various microarray-based methods depend on different pretreatments including immunoprecipitation and restriction digestion. Al-though each technique has its limitations, the immunoprecipitation method has high specificity, and the restriction digestion method shows high sensitivity. Together they provide many choices to the study of genome-wide DNA methylation profile in cancer.

[The relationship of mTOR signaling pathway and histone acetylation in human gastric cancer cell lines].

OBJECTIVE: To evaluate the relationship between mammalian target of rapamycin (mTOR) signaling pathway and histone acetylation in cell survival, cell cycle, gene expression and protein level on human gastric cancer cells. METHODS: Human gastric cancer cell lines, MKN45 and SGC7901 were treated with trichostatin A, rapamycin and/or LY294002, a PI3K inhibitor. Cell viability was analyzed by methylthiazolyl tetrazolium. Cell cycle distribution was evaluated by flow cytometry. The transcription level of p21(WAF1) gene was detected by using real-time polymerase chain reaction. Proteins were detected by Western blotting. RESULTS: Cell viability remarkably reduced after treatment by more than two drugs (P< 0.01). Through flow cytometry assessment, MKN45 cells were arrested in G2 phase (P< 0.05), while SGC7901 cells were in G2 or G1 phase (P< 0.05) whether treated with single or more than two drugs. The expression of p21(WAF1) mRNA was remarkably increased in the gastric cancer cells treated with conjoined drugs (P< 0.01). Phosphorylation of Akt, p70S6K and 4E-BP1 was significantly reduced in cells treated with conjoined drugs (P< 0.01). And histone acetylation of H4/H3 was also increased in cells treated with conjoined drugs (P< 0.01). CONCLUSION: mTOR singnaling pathway has an important relationship with histone acetylation in gastric cancer cell lines. There is a co-effect of mTOR inhibitor and histone deacetylase inhibitor on gastric cancer cells.

Downregulation of ZNF278 arrests the cell cycle and decreases the proliferation of colorectal cancer cells via inhibition of the ERK/MAPK pathway.

Zinc finger protein 278 is a zinc finger transcription factor encoded on the 22q12.2 chromosome. Previous studies revealed that ZNF278 expression was significantly upregulated in colorectal cancer (CRC) tissue compared to adjacent non-tumor tissue. However, the expression and specific roles of ZNF278 in CRC remain unknown. ZNF278 expression was knocked down using specific siRNAs, which was confirmed by western blotting, and the effects of ZNF278 siRNAs on CRC cell proliferation were investigated. In addition, the effects of ZNF278 overexpression were confirmed by western blotting and cell proliferation assay. Correlations between ZNF278 and the ERK/MAPK pathway were also detected by western blotting. We found that ZNF278 knockdown significantly induced cell cycle arrest, resulting in cyclin D1/E1 downregulation and p21 upregulation. Moreover, we demonstrated that downregulation of ZNF278 decreased the proliferation of CRC cells via inhibition of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway for the first time. In conclusion, ZNF278 played a prominent role in the pathogenesis of CRC, and promoted CRC cell proliferation via the ERK/MAPK pathway, suggesting that it may act as a potential target in the diagnosis or treatment of CRC.

High expression of GPR116 indicates poor survival outcome and promotes tumor progression in colorectal carcinoma.

Previous studies have found that G-protein-coupled receptor 116 (GPR116) is a regulator of breast cancer metastasis. However, the role of GPR116 in colorectal carcinoma (CRC) carcinogenesis and progression is unknown. In this study, We found GPR116 expression was significantly up-regulated in CRC specimens compared with corresponding non-cancerous tissues. Increased GPR116 expression in CRC was correlated with histological differentiation and distant metastasis. In addition, high expression of GPR116 was significantly associated with poor overall survival of CRC patients, which was also confirmed by GSE14333, GSE17536 and GSE33113 datasets from the Gene Expression Omnibus (GEO). Furthermore, we demonstrated that the ability of proliferation and invasion of CRC cell lines HCT116 and LOVO was markedly reduced after transfected with siRNA-GPR116. Meanwhile, GPR116 may drive EMT in CRC cells through AKT/EKR signaling pathway, resulting in metastasis. Thus, GPR116 may be a novel reliable prognostic indicator and a risk factor in CRC progression.