Eleven new scalarane sesterterpenoids, including three 20,24-bishomo-25-norscalaranes, carteriofenones A–C (1–3), and eight 20,24-bishomoscalaranes, carteriofenones D–K (4–11), along with two known analogues (12 and 13), were obtained from the marine sponge Carteriospongia foliascens collected from the South China Sea. Their planar structures and relative configurations were elucidated by extensive NMR spectroscopic data. The absolute configuration of 3 was determined using the modified Mosher's method on its hydrolysis product. Scalarane sesterterpenoids with 4-methylpentanate or pentanoate substituents at the 12-position (1–8) were reported for the first time. Carteriofenones E–H (5–8) represented rare naturally occurring scalarane sesterterpenoids with a cyclobutane ring. Compound 4 showed cytotoxicity against the mouse lymphocytic leukemia cell line (P388) with an IC50 value of 0.96 μM.
Gastric cancer (GC) with pulmonary metastasis is one of the deadliest diseases in the world; however, the underlying pathological mechanisms and potential therapeutic targets remain to be elucidated. As exosomes play indispensable roles in the formation of premetastatic niches (PMN) and cancer metastasis. Therefore, investigating the underlying mechanisms of exosome-mediated pulmonary metastasis of GC may shed new light on identifying novel therapeutic targets for GC treatment. GC-derived exosomes were isolated from the conditioned medium of mouse forestomach carcinoma (MFC) cell line. The effects of MFC-derived exosomes on pulmonary macrophage polarization were analyzed by reversetranscription polymerase chain reaction and flow cytometry. Expression of PD-L1 and other proteins was evaluated by Western blot. Exosomal microRNAs (miRNAs) were analyzed by microarray. GC-derived exosomes (GC-exo) accumulated in high numbers in the lungs and were ingested by macrophages. The extracellular-signalregulated kinase (ERK) signaling pathway was activated by GC-exo, inducing macrophage immunosuppressive-phenotype differentiation and increased PD-L1 expression. miRNA-sequencing identified 130 enriched miRNAs in GC-exo. Among the enriched miRNAs, miR-92a-3p plays a major role in activating ERK signaling via inhibition of PTEN expression. In addition, inhibiting ERK signaling with PD98059 significantly reduced the expression of PD-L1 in macrophages and, therefore, reversed the immunosuppressive PMN and inhibited the colonization of GC cells in the lungs. This study identified a novel mechanism of GC-exo mediated PD-L1 expression in lung macrophages that facilitates lung PMN formation and GC pulmonary metastasis, which also provided a potential therapeutic target for GC with pulmonary metastasis treatment.
A new indole-diterpenoid, penijanthine E (1), and a known analogue (2), were obtained from the PDB culture of the marine-derived fungus Penicillium citrinum ZSS-9. The absolute configuration of 1 was elucidated by calculated TDDFT ECD and DP4plus calculations. The absolute configuration of 2 was confirmed by single-crystal X-ray diffraction analysis and TDDFT ECD calculations. Compounds 1 and 2 showed antiviral activity against influenza A virus (IAV) of A/WSN/33(H1N1) and A/PR/8/34(H1N1) strains with IC 50 values ranging from 12.6 to 46.8 μM.
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