Nucleic acid-triggered tumoral immunity propagates pH-selective therapeutic antibodies through tumor-driven epitope spreading.

Important roles of humoral tumor immunity are often pointed out; however, precise profiles of dominant antigens and developmental mechanisms remain elusive. We systematically investigated the humoral antigens of dominant intratumor immunoglobulin clones found in human cancers. We found that approximately half of the corresponding antigens were restricted to strongly and densely negatively charged polymers, resulting in simultaneous reactivities of the antibodies to both densely sulfated glycosaminoglycans (dsGAGs) and nucleic acids (NAs). These anti-dsGAG/NA antibodies matured and expanded via intratumoral immunological driving force of innate immunity via NAs. These human cancer-derived antibodies exhibited acidic pH-selective affinity across both antigens and showed specific reactivity to diverse spectrums of human tumor cells. The antibody-drug conjugate exerted therapeutic effects against multiple cancers in vivo by targeting cell surface dsGAG antigens. This study reveals that intratumoral immunological reactions propagate tumor-oriented immunoglobulin clones and demonstrates a new therapeutic modality for the universal treatment of human malignancies.

Array-based fluorescence assay for serine/threonine kinases using specific chemical reaction.

We report herein the development of an efficient fluorescence assay for serine/threonine kinases using a peptide array. Our approach is based on chemical reactions specific to phosphoserine and phosphothreonine residues, that is, base-mediated beta-elimination of the phosphate group and subsequent Michael addition of a thiol-containing fluorescent reagent. This procedure enables the covalent introduction of a fluorescent moiety into the phosphorylated peptide. Novel fluorescent reagents were designed for this purpose and synthesized. With these reagents, protein kinase A (PKA) and Akt-1 activities were readily detected. Our method can also be used to measure the activity of kinase inhibitors. This assay is expected to be widely applicable in kinase research.

[Selective recognition and detection of biomacromolecules utilizing chemical property of amino Acid or Peptide].

Recently, the fluorometric detection of biomacromolecules has attracted much attention. In this paper, we report the development of two new techniques utilizing the chemical properties of amino acids or peptides: 1) a fluorescence assay for serine/threonine kinase activity; and 2) "turn-on" fluorescent probes for protein labeling, which could be useful for bioimaging. To develop the novel kinase assay, we utilized the chemical reactivity of phosphorylated serine or threonine. Phosphorylated peptide on resin was successfully labeled fluorescently via base-mediated beta-elimination, followed by Michael addition with novel coumarin derivatives. Protein kinase A and casein kinase I activities were detectable with our method. Also, this method was confirmed to be applicable for kinase inhibitor screening. For the development of the novel protein labeling technique, the selective interaction between "His-tag (His(6))" and "metal ion nitrilotriacetic acid (NTA) complex" was utilized. This interaction is useful for protein purification and immobilization. We designed fluorescent probes composed of a fluorophore and Ni2+ or Co2+-NTA complex. These probes were found to be weakly fluorescent as expected. When His-tag peptide was added, these probes became brightly fluorescent. On the other hand, these probes remained non fluorescent with the addition of angiotensin I (H-Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-OH). These probes will be powerful tools for the bioimaging of target proteins.

On-bead fluorescence assay for serine/threonine kinases.

[chemical reaction: see text]. A novel fluorescence-based assay for serine/threonine kinases is described. Base-mediated beta-elimination of the phosphate moiety and the Michael addition of a thiol-containing fluorescent molecule allows convenient and efficient detection of the enzyme activity. This approach may be broadly applicable to various serine/threonine kinases.

Comprehensive quantitative and qualitative liquid chromatography-radioisotope-mass spectrometry analysis for safety testing of tolbutamide metabolites without standard samples.

Liquid chromatography-radioisotope-mass spectrometry (LC-RI-MS) analysis was used to determine the structures of 12 (four previously unknown) (14) C-tolbutamide (TB) metabolites in rat biological samples (plasma, urine, bile, feces, and microsomes). The four novel metabolites are ω-carboxy TB, hydroxyl TB (HTB)-O-glucuronide, TB-ortho or meta-glutathion, and tolylsulphoaminocarbo-glutathion. In rat plasma, after oral administration of (14) C-TB at therapeutic dose (1 mg/kg) and microdose (1.67 µg/kg), the total RI and six metabolites [HTB, carboxy TB (CTB), M1: desbutyl TB, M2: ω-hydroxyl TB, M3: α-hydroxyl TB, and M4: ω-1-hydroxyl TB] were quantified by LC-RI-MS. The plasma concentrations were calculated using their response factors (MS-RI intensity ratio) without standard samples, and the area under the curve (AUC) of plasma concentration per time for evaluation of Safety Testing of Drug Metabolites (MIST) was calculated using the ratio of TB metabolites AUC/total RI AUC. The ratios were as follows: TB 94.5% and HTB 2.5% for the microdose (1.67 µg/kg) and TB 95.6%, HTB 0.96%, CTB 0.065%, M1 0.62%, M2 0.0035%, M3 0.077%, and M4 0.015% for the therapeutic dose (1 mg/kg). These values were less than 10% of the MIST criteria.