Hisahide Hiura

Novel monoclonal antibody-based enzyme immunoassay for determining plasma levels of ADAMTS13 activity

BACKGROUND: ADAMTS13 specifically cleaves unusually large von Willebrand factor (VWF) multimers, which induce platelet thrombi formation under high shear stress. ADAMTS13 activity is deficient in patients with thrombotic thrombocytopenic purpura (TTP). The determination of plasma levels of ADAMTS13 activity is a prerequisite for a differential diagnosis of thrombotic microangiopathies. Here, a unique and highly sensitive enzyme immunoassay (EIA) of ADAMTS13 activity is described.

Mitochondrial p32/C1QBP is highly expressed in prostate cancer and is associated with shorter prostate-specific antigen relapse time after radical prostatectomy

Mitochondria are key organelles for ATP production and apoptosis. Therefore, impairment of mitochondria can modulate or accelerate cancer progression. p32, originally identified as a pre‐mRNA splicing factor SF2/ASF‐associated protein, is localized predominantly in the mitochondrial matrix and involved in mitochondria respiration. Recently, p32 was implicated in apoptosis and resultantly cancer progression. However, little is known about the expression and function of p32 in human tumors including prostate cancer. Here, we investigated the expression of p32 in 148 prostate carcinoma tissues by immunohistochemistry and found a positive correlation of p32 expression to clinicopathological parameters including follow‐up data. p32 is highly expressed in prostate tumor samples and its expression is significantly associated with the Gleason score, pathological stage and relapse. For localized cancers, high p32 is a strong and independent predictor of clinical recurrence in multivariate analysis (P = 0.01). In addition, p32 is overexpressed in the prostate cancer cell lines examined. The selective knockdown of p32 by RNA interference inhibits the growth of prostate cancer cell lines but not of a non‐cancerous cell line. The p32 RNA interference decreases cyclin D1, increases p21 expression and causes a G1/S cell cycle arrest in prostate cancer cells. These data suggest that p32 is critical for prostate cancer cell proliferation and may be a novel marker of clinical progression in prostate cancer. (Cancer Sci 2011; 102: 639–647)

Proteolytic fragmentation and sugar chains of plasma ADAMTS13 purified by a conformation-dependent monoclonal antibody

ADAMTS13 is a metalloproteinase that specifically cleaves unusually large von Willbrand factor multimers under high-shear stress. Deficiency of ADAMTS13 activity induces a life-threatening generalized disease, thrombotic thrombocytopenic purpura. We established a simple and efficient method to purify plasma ADAMTS13 (pADAMTS13) from cryosupernatant using an anti-ADAMTS13 monoclonal antibody (A10) that recognizes a conformational epitope within the disintegrin-like domain. Using the purified pADAMTS13, the amino acid residues involved in cleavage by thrombin, plasmin and leucocyte elastase were determined, and the carbohydrate moieties of this enzyme was analysed by lectin blots. Purified pADAMTS13 had a specific activity of 300 U/mg (25,057-fold purification) and the pI was 5.1-5.5. Cleavage sites of the purified pADAMTS13 by three proteases were identified; thrombin cleaved the four peptidyl bonds between Arg257-Ala258, Arg459-Ser460, Arg888-Thr889 and Arg1176-Arg1177, plasmin cleaved the three peptidyl bonds between Arg257-Ala258, Arg888-Thr889 and Arg1176-Arg1177, and elastase cleaved the two peptidyl bonds between Ile380-Ala381 and Thr874-Ser875. Lectin blot analysis indicated the presence of non-reducing terminal α2-6 and α2-3-linked sialic acid residues with penultimate β-galactose residues on the N- and O-linked sugar chains of pADAMTS13, suggesting that pADAMTS13 is cleared from the circulation via the hepatic asialoglycoprotein receptor like other plasma glycoproteins.

Plasma Levels of ADAMTS13 Antigen Determined with an Enzyme Immunoassay Using a Neutralizing Monoclonal Antibody Parallel ADAMTS13 Activity Levels

Measurements of plasma ADAMTS13 activity (ADAMTS13: AC) have been used for the diagnosis of patients with thrombotic thrombocytopenic purpura (TTP); however, the clinical usefulness of plasma ADAMTS13 antigen (ADAMTS13:AG) has been controversial, because antigen values vary widely among patients with acquired idiopathic TTP (ai-TTP). We have developed a novel enzyme-linked immunosorbent assay (ELISA) for the determination of plasma ADAMTS13:AG. This highly sensitive ELISA system using a neutralizing monoclonal antibody enables the detection of as little as 0.1 % of the level in normal human plasma, corresponding to approximately 1 ng/mL purified plasma ADAMTS13. The mean (± 2 SD) plasma level of ADAMTS13:AG in healthy individuals was 106.4% ± 39.3% (n = 52). Patients with Upshaw-Schulman syndrome (USS) (n = 20) and ai-TTP (n = 30) showed significantly reduced ADAMTS13:AG levels (0.5% ± 1.6% and 1.2% ± 3.4%, respectively). The ADAMTS13:AG level was 48.4% ± 42.6% in USS carriers (n = 40) and <8.3% in ai-TTP patients with <0.5% ADAMTS13:AC. These values were almost parallel to those for ADAMTS13:AC. This ELISA may be useful for the rapid determination of ADAMTS13: AG. Further investigations of this antigen would be helpful in advancing the understanding of the pathogenesis of congenital and acquired TTP.

High-throughput single-base mismatch detection for genotyping of UDP-glucuronosyltransferase (UGT1A1) with probe capture assay coupled with modified allele-specific primer extension reaction (MASPER).

We have developed a new method based on specific primer extension reactions coupled with plate hybridization for high‐throughput genotyping of single‐base mutations. To improve the switching characteristics of the primer extension reaction, we introduced an artificial mismatch two bases upstream of the 3′‐terminal base in the detection primers. A set of primers that correspond to wild‐type and mutant DNA segments can be used to accurately analyze single‐base mutations. The termini of these primers are at the mutation positions. The primer extension products produced by polymerase chain reaction (PCR) were captured by an oligonucleotide probe immobilized on the surface of microtiter wells and were detected by a colorimetric assay using the streptavidin‐conjugated horseradish peroxidase. We used the new method to genotype 96 individuals for 211G>A (G71R) and 119 for 1456T>G (Y486D) in the UDP‐glucuronosyltransferase1A1 gene; the results were completely concordant with those found by direct sequencing. The proposed method includes ordinary PCR and a microplate assay format, and may be used in routine laboratory tests. J. Clin. Lab. Anal. 24:85–91, 2010.