Chemical Incorporation of Chain-Terminating Nucleoside Analogs as 3′-Blocking DNA Damage and Their Removal by Human ERCC1-XPF Endonuclease

Nucleoside/nucleotide analogs that lack the 3′-hydroxy group are widely utilized for HIV therapy. These chain-terminating nucleoside analogs (CTNAs) block DNA synthesis after their incorporation into growing DNA, leading to the antiviral effects. However, they are also considered to be DNA damaging agents, and tyrosyl-DNA phosphodiesterase 1, a DNA repair enzyme, is reportedly able to remove such CTNA-modifications of DNA. Here, we have synthesized phosphoramidite building blocks of representative CTNAs, such as acyclovir, abacavir, carbovir, and lamivudine, and oligonucleotides with the 3′-CTNAs were successfully synthesized on solid supports. Using the chemically synthesized oligonucleotides, we investigated the excision of the 3′-CTNAs in DNA by the human excision repair cross complementing protein 1-xeroderma pigmentosum group F (ERCC1-XPF) endonuclease, which is one of the main components of the nucleotide excision repair pathway. A biochemical analysis demonstrated that the ERCC1-XPF endonuclease cleaved 2–7 nt upstream from the 3′-blocking CTNAs, and that DNA synthesis by the Klenow fragment was resumed after the removal of the CTNAs, suggesting that ERCC1-XPF participates in the repair of the CTNA-induced DNA damage

Primary gastric low-grade fibromyxoid sarcoma with FUS-CREB3L1 fusion – A hitherto undescribed origin of Evans tumor

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue neoplasm with a deceptively benign histological appearance. Only several LGFMS cases originating from the gastrointestinal tract have been reported, but all of them are from the small intestine or colon. Here, we describe a case of gastric LGFMS that was proven to have a characteristic FUS-CREB3L1 fusion gene. A 54-year-old Japanese female complained of epigastralgia. Abdominal computed tomography revealed a solid mass probably originating from the lessercurvature of the gastric body and protruding outside the gastric wall. Under the clinical diagnosis of suspicious gastrointestinal stromal tumor of the stomach, gastric wedge resection including the tumor was done. The macroscopic finding showed a mass approximately 8.0cm in maximal diameter with white-tan cut surface, arising from the gastric wall. Histological examination revealed a mesenchymal tumor consisting of blunt spindle cells with occasional collagen rosettes and inflammatory cells. Tumor was immunohistochemically positive for MUC4 and the molecular analysis using formalin-fixed paraffin embedded tissue detected FUS-CREB3L1 fusion which is a minor fusion gene type in LGFMS. Thus, the pathological diagnosis of gastric LGFMS was confirmed. To the best of our knowledge, the present case is the first one of LGFMS arising from the stomach in the English literature. Keywords: Low-grade fibromyxoid sarcoma, FUS-CREB3L1 fusion, Stomac

A Novel Natural Product-Derived Compound, Vestaine A1, Exerts both Pro-Angiogenic and Anti-Permeability Activity via a Different Pathway from VEGF

Background/Aims: Vascular endothelial growth factor (VEGF) is a key molecule in the regulation of both angiogenesis and vascular permeability. However, it is known that overproduction of VEGF induces abnormal blood vessel formation and these vessels cause several disease pathologies, such as diabetic retinopathy. The purpose of this study was to find novel vasoactive compounds which have different properties from VEGF. Methods/Results: We screened a natural product library using a co-culture angiogenic assay of endothelial cells and fibroblasts. By focusing on morphological changes of endothelial cells, we isolated the novel compounds vestaine A1 and vestaine B1 from the cultured broth of an actinomycete strain, Streptomyces sp. SANK 63697. Vestaine A1 enhanced tube formation of endothelial cells in Matrigel and suppressed cell death induced by serum deprivation. Vestaine A1 activated both MEK1/2 and PI-3 kinase pathways independently of the VEGF pathway in a dose- and time-dependent fashion. Finally, vestaine A1 potently suppressed VEGF-induced vascular permeability both in vitro and in vivo. Conclusion: Vestaine A1 has the potential to exhibit both pro-angiogenic and anti-permeability properties, and would therefore be useful for therapeutic treatment for abnormal vascular permeability-related diseases