Fumitsugu Hino

Isolation of two novel genes, down-regulated in gastric cancer.

Using a differential display technique, we identified two genes that are down‐regulated in human gastric cancer tissue as compared to normal gastric mucosa. The down‐regulated expression of these genes in gastric cancer tissue was confirmed by northern blotting analysis and RT‐PCR. One, CA11, was a novel gene expressed predominantly in the stomach and was depleted in all of the gastric cancer cell lines examined. The other gene, GC36, was homologous to the digestive tract‐specific calpain gene, nCL‐4. The expression of both GC36 and nCL‐4 was suppressed or depleted in gastric cancer cell lines of differentiated and poorly differentiated types. This is the first report of genes, the expression of which is down‐regulated with considerable frequency in gastric cancer.

A one step sandwich enzyme immunoassay for γ-carboxylated osteocalcin using monoclonal antibodies

A highly sensitive, simple and reliable one-step sandwich enzyme immunoassay (EIA) for the gamma-carboxylated form of osteocalcin (Gla-OC) has been developed using a monoclonal antibody. The minimum amount of Gla-OC detected by this EIA was approximately 0.2 ng/ml when a 10 microliter aliquot of the sample was used. The serum Gla-OC level in 30 healthy subjects was 3.6 +/- 2.19 ng/ml (mean +/- SD). A significant increase was seen in patients with chronic renal failure (20.3 +/- 4.60 ng/ml), atherosclerosis (8.3 +/- 4.94 ng/ml) and osteoporosis (10.1 +/- 4.60 ng/ml). The correlation between the values obtained by the sandwich EIA and competitive RIA methods was given by the linear regression equation, y = 2.896 + 0.759 chi, for which the correlation coefficient (r) was 0.815 (n = 58). This newly developed Gla-OC specific EIA may be useful for the diagnosis of metabolic bone disease and ectopic calcification.

Isolation and characterization of two monoclonal antibodies that recognize remote epitopes on the cell-binding domain of human fibronectin☆

Two monoclonal anti-fibronectin antibodies that inhibit fibronectin-mediated cell adhesion have been established and characterized. One antibody, FN12-8, inhibited attachment of rat kidney fibroblasts on the fibronectin-coated substrate in a concentration-dependent manner, attaining a maximal inhibition of greater than 85% at 850 micrograms/ml. Another antibody, FN30-8, caused about 70% inhibition at a concentration as low as 0.85 microgram/ml, although further increase of the antibody concentration did not significantly augment the inhibitory effect. Immunoblot analysis with defined proteolytic fragments revealed that both antibodies are directed to the cell-binding domain of fibronectin. The epitopes for these antibodies were further narrowed down using recombinant cell-binding fragments expressed in Escherichia coli. FN12-8 recognized the 11.5-kDa cell-binding fragment previously characterized by Pierschbacher et al. (1981, Cell 26, 259-267), suggesting that FN12-8 blocks the Arg-Gly-Asp (RGD) cell adhesion signal. FN30-8 could not bind this fragment but did recognize a longer cell-binding fragment containing additional greater than 111 amino acid residues upstream of the 11.5-kDa fragment. Since the RGD-dependent cell adhesion seems to require another signal located at a region 50-160 residues upstream of the 11.5-kDa fragment for full activity, FN30-8 may exert its inhibitory effect by blocking the latter signal.

Increased fragmentation of urinary fibronectin in cancer patients detected by immunoenzymometric assay using domain-specific monoclonal antibodies.

Monoclonal antibodies (MoAbs) recognizing the distinct domains of human fibronectin had previously been established and they were used to construct several sandwich immunoenzymometric assays (IEMAs) for the structural analysis of fibronectin found in the urine of cancer patients. Urinary fibronectin (UFN) was immunodetectable only with FN12-8 and FN30-8 MoAbs against cell-binding domains and was less reactive with other IEMAs using MoAbs directed to terminal domains, indicating that UFN was almost completely fragmented and consisted mainly of cell-binding regions. The IEMA using MoAbs against cell-binding domains had sufficient immunoreactivities with the antigen fragmented by artificial proteolysis, but these fragments could hardly be detected by other IEMAs. UFN levels were significantly elevated in various cancer patients and extremely elevated in some patients with distant metastasis. It is presumed that UFN fragments which increase in cancer patients are generated by extracellular matrix destruction. Thus UFN levels and the ratio of the fragmented UFN level to the non-fragmented UFN level appear to be informative clinical indicators of tumor malignancy or metastatic ability in cancer patients.

Urinary laminin fragments as a tumour marker potentially reflecting basement membrane destruction.

The presence of soluble laminin fragments in urine of healthy subjects, patients with diabetes, and patients with tumours was studied using sandwich immunoenzymometric assay technique. The form of urinary laminin (ULN) fragments was dramatically different from that of intact laminin, so ULN could be detected only by using monoclonal antibodies. Mean levels of ULN in lung tumour were significantly higher (171 micrograms gram-1 creatinine) than those in healthy subjects, patients, with diabetes, patients with stomach tumour, and patients with colon tumour (respectively 91, 92, 77 and 53 micrograms gram-1 creatinine). Immunopurified ULN fragments showed an apparent molecular mass of 42 KD on electrophoresis. This fragment was recognised as being derived from the N-terminal region of laminin B2 chain, because the N-terminal residues of ULN were found to be completely homologous to B2 chain. These data suggested that ULN was almost all fragmented, consisted mainly of N-terminal domain of the B2 chain, and was suspected of a tumour-associated protein fragments probably derived from basement membrane degraded proteolytically by tumour cells. ULN, increased in tumour patients, could be a potential clinical marker for monitoring the turnover of basement membrane in tumours.

DIRECT MEASUREMENT OF CALPASTATIN SUBTYPES BY SANDWICH ENZYME IMMUNOASSAY USING MONOCLONAL ANTIBODIES

Six stable hybridoma cell lines secreting monoclonal antibodies to human calpastatin were established. All monoclonal antibodies belong to the IgG1 subclass and recognized different epitopes on calpastatin. At least two groups were distinguished; the first group was specific for muscle-type (M-) calpastatin and the second group recognized not only M-calpastatin but also erythrocyte-type (E-) calpastatin. The inhibitory effect of all monoclonal antibodies on calpastatin activity was relatively low even at high concentrations of antibodies. Enzyme immunoassay systems were developed for direct determination of calpastatin subtypes in human cells requiring no other sample treatment than the disruption of the cells. The assay methods were, in principle, based on the sandwich enzyme immunoassay using epitope-specific monoclonal antibodies. The enzyme immunoassay system for M-calpastatin was specific for M-calpastatin and could not detect E-calpastatin. The enzyme immunoassay system for total calpastatin detected not only M-calpastatin but also E-calpastatin. The sensitivity of these assay systems was 10 pmol l-1 of calpastatins. Antigenicity of calpastatins was found to be unchanged in the presence of EDTA and haemoglobin. Good reproducibilities of within-and between-assay series and excellent recovery of exogenous calpastatins from cell lysates were observed. From these results, it seems that our newly developed subtype-specific enzyme immunoassay systems for calpastatins are useful in biochemical studies and clinical testing for determination of calpastatin subtypes.

Sandwich enzyme immunoassay for serum integrins using monoclonal antibodies

We produced monoclonal antibodies (mABs) against human integrins. Competitive enzyme-linked immunosorbent assay (ELISA) revealed that each mAB bound to different antigenic determinants. We then developed sandwich-type enzyme immunoassays (EIAs) to measure the concentration of fibronectin receptor (FNR) and vitronectin receptor (VNR). Serum immunoreactive integrin levels were measured using these EIAs in various liver and malignant diseases. In almost all cases of liver cirrhosis (LC) and hepatocellular carcinoma (HCC), serum integrin levels were significantly elevated, but were in the normal range in gastric, colon, lung cancer, and acute hepatitis (AH). The correlation between serum FNR and VNR levels was statistically significant in all cases of liver disease, and no correlation was observed between these integrin levels and conventional biochemical markers such as AST, ALT, and GGT. The serum integrin levels were demonstrated to be a potential diagnostic marker for hepatic fibrogenesis and carcinogenesis, and these sandwich EIAs could be useful for determination of these integrins in clinical laboratory tests.