Detection of membrane-bound alpha-fetoprotein in human hepatoma cell lines by monoclonal antibody 19F12.

Monoclonal antibodies against human alpha-fetoprotein (AFP) were obtained by the hybridoma technique and studied with regard to their reactivities with the human hepatoma cell lines PLC/PRF/5 and KN, and a spontaneously immortalized cell line derived from fetal liver, NuE, all of which synthesize AFP. One of the monoclonal antibodies, 19F12 (IgG2b) became bound to free AFP which was used as the immunogen with an affinity constant of 3.4 X 10(8) M-1. This value was not much higher than those of two other antibodies, 19B1 (IgG1) and 9D12 (IgG2b). However, only antibody 19F12 showed definite reactivity with AFP-producing cells in analysis using flow cytometry. Immunofluorescence microscopy showed that antibody 19F12 detected AFP over the surface of NuE and PLC/PRF/5 cells with a uniform distribution, whereas definite reactivities of antibodies 19B1 and 9D12 to these cells were not detected. These antibodies did not show the specific binding to a non-AFP-producing human lung cancer cell line, PC-9, or to human peripheral blood lymphocytes. The binding ability of 19F12 to hepatoma cells was shown in both viable and fixed cells. Addition of free AFP inhibited the binding of antibody 19F12 to PLC/PRF/5 cells in a concentration-dependent manner. The specific reactivity of 19F12 to human AFP was also confirmed by immunostaining of a tissue section of human cancer proved to be AFP positive with AFP-specific antisera. In two-dimensional polyacrylamide gel electrophoresis of the antigen (from membrane fraction of PLC/PRF/5 cells)-antibody (19F12) complex, spots derived from the antibody and a spot (pI 4.7, Mr 65,000) corresponding in pI and molecular weight to AFP were detected. Western blot analysis showed that material in the membrane fraction of PLC/PRF/5 cells recognized by antibody 19F12 has the same molecular weight as human AFP derived from placenta. In a study of reactivities to PLC/PRF/5 cells treated with various enzymes, the reactivity of this antibody decreased when cells were treated with protease and trypsin and increased when lipase was used. The binding of 19F12 to AFP was not inhibited by concanavalin A. The antibody 19F12 appeared to recognize an epitope that is considered to be part of the peptide area of AFP. These results indicate that the reactivity, the amount of bound antibodies, and the distribution of monoclonal antibodies on antigen-producing cells vary, respectively, even though these antibodies were produced using the same antigen as an immunogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Antitumor effect of adriamycin entrapped in liposomes conjugated with anti-human alpha-fetoprotein monoclonal antibody.

The monoclonal antibody, 19-F-12 (IgG2b), against human alpha-fetoprotein was conjugated to liposomes containing Adriamycin, and the therapeutic effects of the conjugate were experimentally studied using the alpha-fetoprotein-producing human hepatoma strain, Li-7, maintained in BALB/c nu/nu male mice. Three i.v. injections of liposomes containing Adriamycin (7.5 mg/kg) into tumor-bearing mice significantly inhibited the tumor growth, and the therapeutic effect of the antibody-conjugated liposomes was greater than that of unconjugated liposomes, as judged from the tumor weights and histological findings. Furthermore, the experiments were repeated with Adriamycin (4-5 mg/kg) in free form, since administration of Adriamycin (7.5 mg/kg) in free form was highly toxic for the mice. The results still indicated that the therapeutic effect of Adriamycin in 19-F-12 conjugated liposomes was superior to that of free Adriamycin or Adriamycin in unconjugated liposomes. In contrast to the treatment for Li-7 in nude mice, the therapeutic effect of Adriamycin in 19-F-12 conjugated liposomes was not much different from that of Adriamycin in normal mouse IgG (IgG2b fraction) conjugated liposomes against alpha-fetoprotein-negative human breast cancer strain MX1. Tissue distribution studies after i.v. injection of Adriamycin in various forms into mice revealed that preferential delivery of Adriamycin to tumors occurred to some extent with antibody-conjugated liposomes as compared to the unconjugated liposomes. In addition, reduction of the distribution of Adriamycin to the heart was achieved by administering the drug in the liposome-entrapped form, and this enabled the use of a higher dose (7.5 mg/kg) of Adriamycin without toxic side effect.

Immunoliposomes bearing polyethyleneglycol-coupled Fab' fragment show prolonged circulation time and high extravasation into targeted solid tumors in vivo.

We have developed a new type of long-circulating immunoliposome (Fab'-PEG immunoliposomes) which is efficiently extravasated into the targeted solid tumor in vivo. Small unilamellar liposomes (100-130 nm in diameter) were prepared from distearoylphosphatidylcholine (DSPC), cholesterol (CHOL) and a dipalmitoylphosphatidylethanolamine derivative of PEG with a terminal maleimidyl group (DPPE-PEG-Mal), and conjugated Fab' fragment of antibody. Inclusion of DPPE-PEG-Mal and linkage of the Fab' fragment instead of intact antibody to PEG terminals allowed the liposomes to evade RES uptake and remain in the circulation for a long time, resulting in enhanced accumulation of the liposomes in the solid tumor. Because of the ability of such Fab'-PEG immunoliposomes to target solid tumors, they appear highly attractive as carriers of not only chemotherapeutic agents, but also of macromolecular drugs.

Biochemical and immunohistochemical studies on dysmyelination of quaking mutant mice in vivo and in vitro.

Dysmyelination in the central nervous system of the quaking mutant mouse was studied biochemically and immunohistochemically. We found, by measuring CNPase activity, that myelination in the central nervous system of quaking mice was affected to a different degree in different areas. The pallium cerebri was the most severely affected and the medulla and spinal cord were least affected. The density of astroglia observed by GFA staining wash higher in the white matter of quaking mice than in controls, but the total area of the white matter in the cerebellum was smaller in the quaking mice than in the controls. The DNA content in the pallium cerebri and brain stem showed no increase and that of the cerebellum was even lower in quaking mice than in the controls. Hypertrophy of the astroglia was observed in the white matter of the cerebellum of quaking mice, though Bergmann astroglial fibers in the molecular layer did not show any hypertrophy. The cerebella of quaking mice in primary culture showed very poor myelination under the phase-contrast microscope. However, Purkinje cells from the quaking mutants appeared normal with regard to Bodian silver impregnation, hematoxylineosin staining, and Purkinje cell specific P 400 protein. Addition of the conditioned culture medium of qk/qk to the culture of the control cerebellum did not interfere with the myelination. We concluded that the cause of dysmyelination in the quaking mouse could be a genetic defect of the oligodendroglia rather than hypertrophy of the astroglial cells.

Electrically controlled proliferation of human carcinoma cells cultured on the surface of an electrode.

Human carcinoma cells, MKN45, were cultured on the surface of a metal-coated plastic plate electrode the potential of which was controlled. The proliferation rate and cell morphology were altered depending on the applied potential. Cell proliferation was halted in the potential range above 0.4 V vs. Ag/AgCl, although cells started to proliferate again when the applied potential was shifted from 0.4 V to 0.1 V vs. Ag/AgCl. Fluorescence probe studies indicated that the fluidity of plasma membrane decreased in association with halting of cell proliferation. These results suggest that electrical stimulation causes cells to temporarily halt proliferation, and that cell proliferation was reversibly controlled by electrode potential. The mechanism is interpreted in relation to the change of plasma membrane structure represented by membrane fluidity.

[Importance of the conjugated antibody for the induction of selective effect of adriamycin conjugated with anti AFP monoclonal antibody and entrapped in liposomes against AFP producing tumors].

We investigated experimentally the effect of adriamycin (ADM) conjugated with anti alpha-fetoprotein (AFP) monoclonal antibodies and entrapped in liposomes (Lip-ADM = AbAFP) in vitro or in vivo. In the present study, we examined the importance of the conjugated antibody for the induction of selective therapeutic effect of Lip-ADM = AbAFP against AFP producing tumors. As the target tumors, AFP producing human hepatoma strain, Li-7, and AFP non-producing human breast cancer strain, MX-1 maintained in BALB/c nu/nu male mice were used. In order to evaluate the importance of the conjugated antibody, we prepared also ADM conjugated with normal mouse IgG, and entrapped in liposomes Lip-ADM = NIgG, of which therapeutic effects were compared with that of Lip-ADM = AbAFP. Judging from the tumor growth curve and the tumor weight, the therapeutic effect of Lip-ADM = AbAFP was greater against Li-7 than that of Lip-ADM = NIgG. On the other hand, both conjugates showed similar effects against MX-1. As the results it is suggested that the antibody which recognizes the antigen expressed on the target tumor cells can solely increase the therapeutic effect of ADM entrapped in liposomes (Lip-ADM) and that the main factors which contribute to the efficient therapeutic effect of the conjugate were the sensitibility to ADM, the affinity of the tumor cells to liposomes and the superiority of the conjugated antibody.

Enhanced expression of hepatocyte growth factor activator inhibitor type 2-related small peptide at the invasive front of colon cancers.

BACKGROUND: Hepatocyte growth factor activator inhibitor type 2-related small peptide (H2RSP) is a small nuclear protein abundantly expressed in the gastrointestinal epithelium. However, its functions remain unknown. AIMS: To investigate the expression and localisation of H2RSP in normal, injured and neoplastic human intestinal tissue. METHODS: Immunohistochemical examination and in situ hybridisation for H2RSP were performed using normal and diseased intestinal specimens. Its subcellular localisation and effects on the cellular proliferation and invasiveness were examined using cultured cells. RESULTS: In the normal intestine, H2RSP was observed in the nuclei of surface epithelial cells and this nuclear localisation was impaired in regenerating epithelium. In vitro, the nuclear translocation of H2RSP was observed along with increasing cellular density, and an overexpression of H2RSP resulted in a reduced growth rate and enhanced invasiveness. H2RSP expression was down regulated in well-differentiated colorectal adenocarcinomas. However, a marked up regulation of the cytoplasmic H2RSP immunoreactivity was observed in cancer cells at the invasive front. These cells showed low MIB-1 labelling, an enhanced p16 expression and nuclear beta-catenin. The number of H2RSP-positive cells in the invasive front of well-differentiated adenocarcinomas was considerably higher in the cases with lymph node metastases than in node-negative ones. CONCLUSION: In the normal intestine, the nuclear accumulation of H2RSP is a marker of differentiated epithelial cells. Although H2RSP was down regulated in colorectal adenocarcinomas, a paradoxical up regulation was observed in actively invading carcinoma cells. H2RSP immunoreactivity at the invasive front may serve as a marker of invasive phenotype of well-differentiated colon cancers.

Understanding and managing change in health care organizations.

Change impacts affected people and often causes difficulties. Health care organizations, locally and nationally, have undergone tremendous change to deliver quality services in a more effective and efficient manner in a competitive environment, with varying degrees of success. This article presents Robbins's categories of change and relates them to current changes in health care organizations. It discusses areas to consider to develop adaptable plans and to assist affected employees to better deal with these changes throughout the transition.

Dysmyelination of shiverer mutant mice in vivo and in vitro.

Demyelination in the CNS of shiverer mutant mice was studied in vivo and in vitro. By immunohistochemical reaction with glial fibrillary acidic protein antibody, hypertrophy of the fibrous astrocytes was observed in the white matter of shiverer cerebella. The cerebella of shiverer mice in primary culture from the day of birth showed very poor myelination under optical microscopy. Axons of Purkinje cells are thought to be the main myelinated axons in the primary culture of the cerebellum. Purkinje cells from shiverer appeared normal with regard to Bodian silver impregnation, hematoxylin and eosin staining, and P400 protein characterization of Purkinje cells. Addition of the conditioned culture medium of shiverer to the control culture did not interfere with myelination. We concluded that the demyelination in the CNS of shiverer could be caused by an intrinsic defect of the oligodendrocyte rather than by hypertrophy of the astrocytes or by diffusible factors.

Subcellular distribution and developmental change of 2',3'-cyclic nucleotide 3'-phosphohydrolase in the central nervous system of the myelin-deficient shiverer mutant mice.

Shiverer is an autosomal recessive mutant characterized by dysmyelination in the central nervous system. The myelin in the shiverer is devoid of the major dense line. The pattern of increase of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) in the various parts of central nervous system during postnatal development was identical with that of controls. Subcellular fractionation of the brain from shiverer showed that the recovery of CNPase activity of the P2A was only 14% of the control, but those of P2B and P3 were several times higher than the controls. The specificity activity of CNPase of the purified myelin and P2A from shiverer did not differ significantly from that of the controls. The combined P2 and P3 (P2 + P3) fraction was subjected to linear sucrose density gradient (0.32--1.3 M) centrifugation. By measuring CNPase activities of the fractions obtained after centrifugation, shiverer showed two peaks of CNPase activities in the sucrose gradient, although that of the control showed a single peak. The main peak obtained from shiverer was found in the region of higher sucrose concentration than that of the control, while a small peak was found in the region of lower sucrose concentration.

Production of monoclonal antibody to 2',3'-cyclic nucleotide 3'-phosphodiesterase from bovine cerebral white matter.

Lewis rats were immunized with partially purified 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) from bovine cerebral white matter and the spleen cells were fused with cell of a mouse myeloma cell line (SP-2). The production of monoclonal antibody was detected by enzyme-linked immunoadsorbent assay, immunohistochemical staining of bovine cerebrum, Western blotting analysis, and CNPase binding assay. Monoclonal antibody that specifically binds CNPase molecules was obtained. However, the antibody did not suppress the enzyme activity. Western blotting analysis demonstrated that the monoclonal antibody binds both CNa (Wla) and CNb (Wlb). The monoclonal antibody was identified as being of the IgG2c subclass. Immunohistochemical examination revealed that the myelin sheath in the CNS was heavily stained with the monoclonal antibody in several species (bovine, mouse, rat, and human). In contrast, peripheral nervous system myelin was not stained even in bovine tissue. These results suggest that the monoclonal antibody obtained in the present study specifically recognizes the CNPase molecules in the CNS.

Electrically promoted protein production by mammalian cells cultured on the electrode surface.

Protein production of mammalian cells has been promoted by applying a small constant potential to the surface of an electrode on which cells are cultured. Human carcinoma line of MKN45 cells were cultured on the surface of a platinum-coated plastic plate electrode. Low d.c. voltage of constant potential was applied to the electrode during 4-day culture to modulate the production of carcinoembryonic antigen (CEA). The amounts of both secreted and membrane-bound CEA were dependent on the applied potential during culture. Secreted CEA was more than twice in amount in the potential range from 0.2 V to 0.6 V vs. Ag/Agcl as compared with that of normal culture. In the potential range, CEA was also increased in membrane-bound form. The potential-controlled cell culture may have an enhanced effect on protein production.

Neuronal survival factor from bovine brain is identical to neuron-specific enolase.

Neuronal survival factors in the central nervous system were investigated by using a primary culture of embryonic rat neocortical neurons. Bovine hippocampus was homogenized, and the supernatant from high-speed centrifugation was used as the starting material. At the step of DE-52 ion-exchange chromatography, neuronal survival activity was recovered in two fractions, fraction 14 (F14) and fraction 23 (F23). Antisera to the crude F14 and F23 fractions were raised in rabbits. These two antisera completely inhibited the neurotrophic activity of both fractions. Western blotting analysis revealed that anti-F14 antiserum recognized mainly a 30-kDa protein in F14 and anti-F23 antiserum recognized mainly a 44-kDa protein in F23. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis of F23, the 44-kDa protein was cut out from the gel and partial amino acid sequences of the protein fragments were determined. A GenBank data bank indicated that the amino acid sequence of the fragment was identical to that of neuron-specific enolase (NSE). In our assay system, commercially available NSE itself possessed neuronal survival activity for the cultured neocortical neurons. The effects of NSE and F23 were inhibited completely by anti-NSE polyclonal antibody. Furthermore, highly purified NSE supported the survival of cultured neurons in a dose-dependent manner, and the neurotrophic effect was inhibited by monoclonal antibody to the NSE. These results strongly suggest that NSE is one of the neuronal survival factors in the central nervous system.

Suppression of the degradation of recombinant human apolipoprotein E by a protease inhibitor obtained from fetal bovine serum in serum-free culture.

The recombinant human apolipoprotein E (Apo-E) produced by Chinese hamster ovary cells (CHO-322 cells) in serum free culture was degraded to 24K and 23K fragments that contained N-terminal amino acid. The degradation site of Apo-E to 24K fragment was between Arg180 and Leu181 and the C-terminal amino acid of 23K fragment was Gly169. In fetal bovine serum (FBS)-containing culture, the degradation was inhibited. However, in calf serum (CS) the inhibitory activity was not detected. Thus, we attempted the purification of the factor with this inhibitory activity from FBS. A protease inhibitor was purified to give a single peak from FBS by ammonium sulfate precipitation and combination of several column chromatographies. When this FBS-derived protease inhibitor (FBS-d-PI) was added to serum-free culture of CHO-322 cells, degradation of recombinant Apo-E to the 24K and 23K fragments was dose-dependently suppressed and accumulation of intact Apo-E in culture supernatant was observed. FBS-d-PI was found to be a glycoprotein with relative molecular size of 75K daltons under reducing condition, and 85K daltons under nonreducing condition by SDS-PAGE. A complex of FBS-d-PI and a cellular protease was also detected in culture supernatant by western blot analysis using mouse monoclonal antibodies against FBS-d-PI.

Efficacy of immunoliposomes on cancer models in a cell-surface-antigen-density-dependent manner.

We have recently established a cancer-reactive human monoclonal antibody, GAH, with a positive ratio of over 90% against stomach cancer. GAH was formulated as polyethyleneglycol (PEG)-modified immunoliposomal doxorubicin (DXR) (ILD) and its efficacy was examined against gastrointestinal human cancers. In in vitro studies, a comparison of ILD with PEG-modified liposomal DXR (LD) demonstrated that ILD had dose-dependent cytotoxicity for GAH-reactive B37 cancer cells, but not LD. In concordance with this result, microscopic observations showed that ILD was bound to and GAH-dependently internalised by B37 cells. In in vivo studies, ILD exhibited significantly greater antitumour activity on cancer xenograft models than LD or free DXR. The relation between efficacy and antigen density was examined on 10 xenograft models bearing cancer cells with varying GAH reactivity. Immunoliposomal doxorubicin therapeutic activity correlated with the antigen density, with a minimum number being required. Also, ILD revealed strong antitumour activity on cancers with low sensitivity to DXR or LD, suggesting that ILD overcame the DXR resistance of antigen-positive cancer cells. Thus, these results show that GAH endows liposomes with targeting activity, resulting in strong efficacy against gastrointestinal cancers.

Effect of alpha-interferon on anti-alpha-fetoprotein-monoclonal-antibody targeting of hepatoma.

We studied the potential of alpha-interferon (IFN-alpha) to enhance alpha-fetoprotein (AFP) and thus alter the localization of 125I-labeled antibody to the human hepatoma xenograft in athymic mice using monoclonal antibody (MAb) 19F12, which recognized AFP on the surface of human hepatoma cells. Treatment of the human hepatoma cell NuE with IFN-alpha increased the surface expression of AFP 2.4-fold in an IFN-dose-dependent manner. The IFN-alpha treatment substantially increased (2.7-fold) the localization of 125I-labeled 19F12 to NuE xenografts in athymic mice. The increase in localization of 125I-labeled 19F12 was dependent on the circulating plasma IFN levels. Our experimental results suggested that IFN-alpha could act as a potent modulator of the cellular antigen AFP, and be used to enhance the targeting of a conjugated MAb to hepatoma cell populations.

Selective inhibition of hepatoma cells using diphtheria toxin A under the control of the promoter/enhancer region of the human alpha-fetoprotein gene.

We constructed a plasmid containing human alpha-fetoprotein (AFP) promoter/enhancer to direct the cell type-specific expression of diphtheria toxin fragment A (DTA), designated as pAF-DTA, to AFP-producing hepatocellular carcinoma cells. The transfection was carried out with cationic liposomes (DMRIE-C) and the expression of the DTA gene was confirmed by a northern blot analysis. When pAF-DTA was transfected, the growth of AFP-positive HuH-7 cells was inhibited, whereas growth inhibition was not observed in AFP-negative MKN45 cells. In this experiment, the secretion of AFP was similarly suppressed, but the secretion of carcinoembryonic antigen from MKN45 was not altered. pAF-DTA could also exert its growth inhibitory effect on PLC, a cell line with a low level of AFP. However, no inhibitory effect of pAF-DTA was observed on the proliferation of primary hepatocyte cells. Furthermore, transfection experiments in which HuH-7 and splenic stromal cells were co-cultured revealed the growth inhibition by pAF-DTA to be selective in HuH-7 cells. Finally, the growth of HuH-7 transplanted on BALB/c nu/nu mice was inhibited by the direct injection of pAF-DTA/liposome complex into a tumor mass. These results suggest that use of pAF-DTA may be potentially useful as a novel approach for the selective treatment of tumor cells producing AFP even at low levels, without affecting other types of cells.

Improvement of pharmacokinetics and antitumor activity against human hepatoma cell line by using adriamycin-entrapped stealth liposomes.

Preferential accumulation in the reticuloendothelial system is one of the major obstacles to the use of liposomes as a drug carrier for targeting therapy. To reduce their uptake, ganglioside GM1 was introduced into the components of conventional liposomes that had been used in our targeting experiments. Two types of such liposomes were prepared. Tissue distribution studies on Adriamycin entrapped in both types of liposomes clearly indicated that the uptake of Adriamycin by liver and spleen decreased to the level comparable to that of free Adriamycin administration. By contrast, the level of Adriamycin in the serum remains high, and some increase was observed in the accumulation to the tumor. Furthermore, Adriamycin in these liposomes, which were conjugated with anti-alpha-fetoprotein (AFP) antibody, inhibited the growth of AFP-positive human hepatoma Li-7 more efficiently than free Adriamycin or Adriamycin in antibody-conjugated conventional liposomes.