In vitro synthesis of oryzamutaic acid H using recombinant L-lysine ε-dehydrogenase from Agrobacterium tumefaciens.

Oryzamutaic acids, possessing a nitrogen-containing heterocyclic skeleton, have been isolated and identified from a rice mutant. Although oryzamutaic acids are expected to be functional ingredients, their functionality is difficult to evaluate, because of their wide variety and presence in trace amounts. Furthermore, how oryzamutaic acid is synthesized in vivo is unclear. Therefore, we developed a simple enzymatic synthesis method for these compounds in vitro. We focused on L-lysine ε-dehydrogenase (LysDH) from Agrobacterium tumefaciens, which synthesizes α-aminoadipate-δ-semialdehyde-a precursor of oryzamutaic acids. LysDH was cloned and expressed in Escherichia coli. Analysis of activity revealed that LysDH catalyzed the synthesis of oryzamutaic acid H at neutral pH in vitro. We synthesized 1.6 mg oryzamutaic acid H from 100 mg L-lysine. The synthesized oryzamutaic acid H exhibited UVA absorption, stability of temperature, and stability at a wide pH range. To our knowledge, this study is the first to report the enzymatic synthesis of oryzamutaic acid H in vitro and provides a basis for understanding the mechanisms of oryzamutaic acid synthesis in vivo.

Definitive Chemoradiotherapy with Docetaxel, Cisplatin, and 5-Fluorouracil for Advanced Cervical Esophageal Cancer: A Medium-Term Outcome.

BACKGROUND: Definitive chemoradiotherapy (dCRT) is widely considered as a treatment option for cervical esophageal squamous cell carcinoma (ESCC) toward preserving the larynx. We have reported favorable outcomes, including the treatment response rate and short-term survival of dCRT concomitant with docetaxel, cisplatin, and 5-fluorouracil (DCF-RT) for advanced cervical ESCC. The aim of this paper was to report the subsequent progress of the study. METHODS: We assessed 18 patients with advanced (clinical stage II-IV, including T4b and/or M1 lymph node) cervical ESCC at our department who received DCF-RT as the first-line treatment between December 2010 and June 2020. RESULTS: A total of 14 men and 4 women underwent the study regimen. The pretreatment clinical stage included stage II, stage III, stage IVA, and stage IVB cases (including 9 patients with T4b) [8 trachea and 2 thyroids] and 7 patients with the M1 lymph node. The complete response (CR) was achieved in 15 patients, stable disease in 2, and progressive disease in 1. Of 15 patients with CR, 7 experienced recurrence, and 8 had continued CR. Frequent cases of grade ≥3 adverse effects included leucopenia, neutropenia, febrile neutropenia, and pharyngeal pain. The 3-year overall survival rate, disease-free survival rate, and disease-specific survival rate were 44.2%, 47.7%, and 48.6%, respectively. CONCLUSION: DCF-RT for advanced cervical esophageal cancer could achieve a favorable prognosis with larynx preservation. Further observations are warranted to establish the long-term prognosis, late complications of radiotherapy, and the significance of salvage surgery.

Molecular basis for the disruption of Keap1-Nrf2 interaction via Hinge & Latch mechanism.

The Keap1-Nrf2 system is central for mammalian cytoprotection against various stresses and a drug target for disease prevention and treatment. One model for the molecular mechanisms leading to Nrf2 activation is the Hinge-Latch model, where the DLGex-binding motif of Nrf2 dissociates from Keap1 as a latch, while the ETGE motif remains attached to Keap1 as a hinge. To overcome the technical difficulties in examining the binding status of the two motifs during protein-protein interaction (PPI) simultaneously, we utilized NMR spectroscopy titration experiments. Our results revealed that latch dissociation is triggered by low-molecular-weight Keap1-Nrf2 PPI inhibitors and occurs during p62-mediated Nrf2 activation, but not by electrophilic Nrf2 inducers. This study demonstrates that Keap1 utilizes a unique Hinge-Latch mechanism for Nrf2 activation upon challenge by non-electrophilic PPI-inhibiting stimuli, and provides critical insight for the pharmacological development of next-generation Nrf2 activators targeting the Keap1-Nrf2 PPI.