Induction of neurite outgrowth in PC12 cells by the medium-chain fatty acid octanoic acid

It has been shown that polyunsaturated fatty acids such as arachinonic and docosahexanoic acids but not monounsaturated and saturated long-chain fatty acids promote basal and nerve growth factor (NGF)-induced neurite extension of PC12 cells, a line derived from a rat pheochromocytoma. On the other hand, short-chain fatty acids and valproic acid (2-propylpentanoic acid) enhance the growth of neurite processes of the cells only in the presence of inducers. In this study, we demonstrated that straight medium-chain fatty acids (MCFAs) at millimolar concentrations alone potently induced neuronal differentiation of PC12 cells. Hexanoic, heptanoic and octanoic acids dose-dependently induced neurite outgrowth of the cells: their maximal effects determined 2 days after addition to the culture medium were more marked than the effect of NGF. PC12 cells exposed to octanoic acid expressed increased levels of the neuronal marker beta-tubulin isotype III. Nonanoic, decanoic, and dodecanoic acids also induced growth of neurite processes, but their maximal effects were less marked than that of octanoic acid. In contrast, the polyunsaturated fatty acid linoleic acid and short-chain fatty acids had only slight or almost no effects on neurite formation in the absence of NGF. The effect of octanoic acid was synergistic with or additive to the effects of NGF and dibutyryl cyclic AMP. Octanoic acid upregulated phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), critical signaling molecules in neuronal differentiation, but not phosphorylation of Akt, a signaling molecule downstream of phosphatidylinositol 3-kinase (PI3K). Moreover, growth of neurites induced by octanoic acid was potently inhibited by treatment of cells with the p38 MAPK inhibitor SB203580 and the ERK kinase inhibitor PD98059 but not inhibited and only slightly inhibited by the JNK inhibitor SP600125 and the PI3K inhibitor wortmannin, respectively. Taken together, our results indicate that MCFAs, including octanoic acid, induced neurite outgrowth of PC12 cells in the absence of NGF and suggest that the activation of p38 MAPK and ERK pathways is involved in this process.

Stimulation of hepatocyte growth factor production in human fibroblasts by the protein phosphatase inhibitor okadaic acid

In this study, we examined whether the production of hepatocyte growth factor (HGF) in fibroblasts is regulated by protein phosphatase(s). Inhibitors of the enzymes okadaic acid and calyculin A were used for this purpose. Both inhibitors markedly stimulated HGF production in human skin fibroblasts in a dose-dependent manner. The effects of okadaic acid and calyculin A were maximal at 25-37.5 and 1.25 nM, respectively. Highly active HGF production in MRC-5 human embryonic lung fibroblasts was also promoted by both inhibitors. The effect of okadaic acid was accompanied by an up-regulation of HGF gene expression. The stimulating effect of okadaic acid on HGF production was synergistic with that of phorbol 12-myristate 13-acetate (PMA) and epidermal growth factor (EGF), whereas it was additive to the effect of cholera toxin. The protein kinase C (PKC) inhibitor GF 109203X inhibited the effect of PMA, but not of okadaic acid and EGF. The effect of okadaic acid as well as EGF was not inhibited, but rather enhanced in human skin fibroblasts pretreated for 24 hr with a high dose of PMA to deplete PKC, as compared with its effect in untreated cells. PD 98059, an inhibitor of mitogen-activated protein (MAP) kinase kinase, suppressed the effects of okadaic acid and EGF, but not those of cholera toxin and 8-bromo-adenosine 3',5'-cyclic monophosphate (cAMP). These results suggest that HGF production in human skin fibroblasts is down-regulated by protein phosphatase(s) and that HGF production stimulated by okadaic acid is, at least in part, dependent on the activation of the MAP kinase cascade.

Synergism between interferon-gamma and cAMP in induction of hepatocyte growth factor in human skin fibroblasts

Interferon (IFN)-gamma stimulates hepatocyte growth factor (HGF) production markedly in various human leukemia cell lines, but its positive effect in human skin fibroblasts is slight. We examined the combined effect of IFN-gamma and various HGF inducers on HGF production in human skin fibroblasts. IFN-gamma synergistically enhanced HGF production stimulated by 8-bromo-cAMP, one of the most effective inducers of HGF: HGF secreted from cells incubated with 1 mM of 8-bromo-cAMP, 1000 U/ml of IFN-gamma and both of these was approximately 8, 1.5 and 24 times, respectively, that secreted from untreated cells. The effect of IFN-gamma was dose-dependent and was nullified by an anti-IFN-gamma antibody. Neither IFN-alpha nor IFN-beta had such an enhancing effect, but both these IFNs inhibited the synergistic effect of IFN-gamma and 8-bromo-cAMP. IFN-gamma also synergistically augmented HGF production induced by interleukin-1beta and cAMP-increasing agents cholera toxin, forskolin and prostaglandin E(2). HGF gene expression upregulated by cholera toxin, forskolin and 8-bromo-cAMP was markedly enhanced by IFN-gamma, which was detected as early as 3 h after its addition. The synergy between HGF inducers and IFN-gamma is not common to all HGF inducers, because HGF production stimulated by epidermal growth factor and protein-kinase-C-activating phorbol esters was significantly inhibited by IFN-gamma. These results indicate that IFN-gamma synergistically stimulates cAMP-induced HGF production and inhibits HGF production induced by growth factors and protein kinase C activators in human skin fibroblasts.

An increase in histone acetylation and IL-2 antagonizing the immunoinhibitory effect are necessary for augmentation by butyrate of in vitro anti-TNP antibody production

We investigated the role of histone acetylation in the promotion of antigen-specific antibody production in murine B cells induced by sodium butyrate (NaBu) plus interleukin 2 (IL-2). NaBu dose dependently increased the acetylation levels of histone H4 at concentrations which effectively enhanced anti-trinitrophenyl (TNP) antibody production in the presence of IL-2. Among other short-chain fatty acids and NaBu analogs, propionate, valerate and vinylacetate were effective in the presence of IL-2 in increasing both antibody production and the histone H4 acetylation level, but acetate, alpha-, beta- and gamma-hydroxybutyrates and alpha-, beta- and gamma-aminobutyrates were not effective, even in the presence of IL-2. The effect of the specific histone deacetylase inhibitor trichostatin A (TSA), which enhances anti-TNP antibody production without IL-2, was markedly inhibited by adding NaBu simultaneously. However, the effect of TSA was neither inhibited nor potentiated by NaBu in the presence of IL-2. Splenic B cells treated with NaBu, TSA and both together in the presence or absence of IL-2 showed almost the same increased acetylation level of histone H4. These results suggest that the NaBu-induced enhancement of anti-TNP antibody production in the presence of IL-2 is mediated through a moderate increase in the level of histone acetylation and that NaBu has both stimulating and inhibiting activities for anti-TNP antibody production, the latter of which is overcome by IL-2.

Promotion of antigen-specific antibody production in murine B cells by a moderate increase in histone acetylation

By employing the specific histone deacetylase inhibitor trichostatin A (TSA), we investigated whether histone acetylation modulates the production of antigen-specific antibodies in murine splenocytes in vitro. TSA caused a marked increase in both anti-sheep red blood cell (SRBC) and anti-trinitrophenyl (TNP) plaque-forming cell (PFC) responses in splenocytes at much lower concentrations than sodium butyrate. It also dose dependently augmented the production of anti-trinitrophenyl antibodies in splenic B cells with a concomitant, moderate increase in the level of histone H4 acetylation. Its optimal concentration for promoting the production of these antibodies was 10 nM. However, to gain such an effect on antibody production, TSA had to be added to cells before Day 2 in culture. Trichostatin C, an analog of TSA and a less potent inducer of Friend leukemia cell differentiation, also increased both the anti-trinitrophenyl PFC response and histone H4 acetylation in B cells, but at higher concentrations than TSA. TSA did not stimulate the production of lipopolysaccharide-induced polyclonal immunoglobulin M in B cells. These results suggest that a moderate increase in histone acetylation may play a significant role in promoting antigen-specific antibody production in B cells.

Possible involvement of p21/waf1 in the growth inhibition of HepG2 cells induced by hepatocyte growth factor

Hepatocyte growth factor (HGF) is a potent mitogen for a variety of cell types, but it is also known as an antimitogenic factor for several types of tumor cell lines. The biological processes by which HGF inhibits tumor cell growth remain poorly understood. Here we report a comparative study of HGF-mediated signal transduction events between two opposite responding types of human hepatoblastoma cell lines, HuH6 and HepG2. Following serum starvation, both cell lines were cultured in hepatocyte growth medium (HGM), a chemically defined medium, in the presence or absence of HGF. Under these culture conditions, cell growth in HuH6 was promoted by HGF, while it was inhibited in HepG2. Phosphorylation of p42/mitogen-activated protein (MAP) kinase was observed within 10 min after HGF stimulation in both cell lines. The level of phosphorylated MAP kinase in HuH6 declined to basal levels after 2 hr. However, in HepG2 the phosphorylated form was detectable at 6 hr. p21/waf1 was induced in both cell lines where levels peaked 4-6 hr after HGF stimulation. In HuH6, a marked decrease of p21/waf1 was observed at 8-12 hr, while a high level of p21/waf1 was sustained for at least 24 hr in HepG2. HGF treatment depressed cdk2 activity in a time-dependent manner in HepG2 while the activity increased in HuH6. When serum-starved HepG2 was growth stimulated with serum in the presence or absence of HGF, the cells treated with HGF underwent growth inhibition correlating with a sustained induction of p21/waf1 and a decrease of cdk2 activity. Immunoprecipitation analysis revealed accumulation of cdk2-associated p21/waf1 in the HGF-treated HepG2. Together, the results suggest that sustained induction of p21/waf1 mediates growth inhibition in HepG2 in the presence of HGF.

Stimulation of hepatocyte growth factor production by ascorbic acid and its stable 2-glucoside

Hepatocyte growth factor (HGF), a cytokine which is generally produced by mesenchymal cells, has mitogenic, motogenic and morphogenic activities in epithelial cells and it also has tumor-suppressing activities. Induction of HGF production may be involved in organ regeneration, wound healing and embryogenesis. We examined the effects of ascorbic acid (AsA), which stimulates the proliferation of fibroblasts, and its stable derivative, 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G), on HGF production by human skin fibroblasts. Basal HGF secretion was significantly stimulated by more than 0.1 mM AsA or AA-2G. Both vitamins synergistically enhanced HGF secretion stimulated by growth factors such as epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), cholera toxin and other inducers. Induction by EGF or bFGF was most markedly potentiated by the vitamins. HGF production by the KG-1 human leukemia cell line was also augmented by AsA or AA-2G. Another stable AsA derivative, ascorbic acid 2-phosphate (AA-2P) effectively promoted basal and EGF-induced HGF secretion by the fibroblasts, but ascorbic acid 2-sulfate (AA-2S) was much less effective. Intracellular AsA levels increased after the addition of AA-2G and AA-2P as well as AsA, but not after AA-2S. The effect of AA-2G was completely abrogated by the simultaneous addition of castanospermine, an alpha-glucosidase inhibitor, suggesting that the active form of AA-2G is AsA. Constitutive and EGF-induced HGF gene expression was also up-regulated after adding AsA or AA-2G to the cells. These results indicated that AsA acts alone or in synergy with several inducers to stimulate the production and gene expression of HGF in human skin fibroblasts and that the stable AsA derivative AA-2G is as effective as AsA in promoting HGF production.

SKW 6.4 cell differentiation induced by interleukin 6 is stimulated by butyrate

We investigated if sodium butyrate (NaBu), an inhibitor of histone deacetylase, and its analogs modulate cytokine-induced differentiation of the human B cell line SKW 6.4 transformed by the Epstein-Barr virus. NaBu markedly enhanced interleukin (IL)-6-induced IgM production with an accompanying increase in the level of histone H4 acetylation and augmented IgM production induced by IL-4 and phorbol 12-myristate 13-acetate. From both the enhancing effect of cell differentiation and the effect of inducing histone hyperacetylation in SKW 6.4 cells, other histone deacetylase inhibitors and NaBu analogs were divided into three groups: those that increased both IL-6-induced antibody production and histone acetylation, those that caused histone hyperacetylation, but failed to induce the differentiation, and those that were ineffective at inducing either activity. No agent that enhanced IgM production without inducing histone hyperacetylation was found among the inhibitors and analogs we tested. These results suggest that the increase in the histone acetylation is necessary, but it is insufficient to augment differentiation of SKW 6.4 cells. Thus another activity of NaBu in addition to the inhibition of histone deacetylase may be involved in promoting IL-6-induced differentiation. Our results also suggest that fatty acids that have a straight chain of four carbon atoms or are branched with four and five carbon atoms, which contain no hydrophilic substituents, or those with similar structures, show this other activity.

Transforming growth factor-beta 1 stimulates or inhibits cell growth via down- or up-regulation of p21/Waf1

Transforming growth factor-beta (TGF-beta) regulates cell proliferation positively or negatively. The mitoinhibition by TGF-beta has been attributed to induction of cyclin-dependent kinase (CDK) inhibitors, such as p15/ Ink4B, p27/Kip1, and p21/Waf1 also known as Cip1 and Sdi1. However, the biological process by which TGF-beta exerts the stimulatory effects on cell growth remains poorly understood. Here we report that TGF-beta 1 stimulates DNA synthesis of IMR-90 human embryonic lung fibroblasts but inhibits that of HuCCT1 human cholangiocarcinoma cells, via down- or up-regulation of p21/Waf1, respectively. TGF-beta 1 markedly suppresses IMR-90 cells to express two different kinds of the p21/Waf1 gene transcription factors, the p53 tumor suppressor and the interferon regulatory factor-1 (IRF-1). This is followed by a marked decrease in expression of p21/Waf1 in a manner consistent with the timing of activation of cyclin E-associated kinase, which normally accompanies the G1-S transition in the cell cycle. Contrarily, TGF-beta 1-induced inhibition of DNA synthesis in HuCCT1 cells is preceded by IRF-1-dependent but p53-independent up-regulation of p21/Waf1 expression followed by inactivation of cyclin E-associated kinase. Thus the cell growth stimulation or inhibition by TGF-beta 1 are mediated by the down- or up-regulation of p21/ Waf1, respectively.

Increased hepatocyte growth factor production by aging human fibroblasts mainly due to autocrine stimulation by interleukin-1

Hepatocyte growth factor (HGF), also known as scatter factor is a pleiotropic factor that is mainly produced by mesenchymal cells and acts on cells of epithelial origin which express the HGF receptor c-Met. Here we demonstrate that production of HGF by human embryonic lung fibroblasts increased sharply after about 70% completion of their lifespan in culture, which is regulated at the transcriptional level. In addition, human skin fibroblasts from old donors, over 80 years, also produced more HGF than cells from young and middle-aged donors. The increased production of HGF by aging fibroblasts from human embryonic lung tissue is mainly due to autocrine stimulation by interleukin-1.

Induction of apoptosis by hepatocyte growth factor/scatter factor and its augmentation by phorbol esters in Meth A cells

Hepatocyte growth factor/scatter factor (HGF/SF) is a multifunctional cytokine with mitogenic, motogenic, and morphogenic activities. In addition, HGF/SF inhibits the proliferation of some tumor cell lines, but its mechanism remains poorly understood. We determined in this study whether HGF/SF induces cell death of a Meth A mouse sarcoma cell line in vitro, whose proliferation is remarkably suppressed by HGF/SF. Inhibition of Meth A cell growth by HGF/SF was dose-dependent and maximal at a concentration of 30 ng/ml. The percentage of dead cells increased to 22% upon treatment with 30 ng/ml of HGF/SF for 96 h, whereas that in untreated cultures was less than 5%. Staining of these cells nuclei with Hoechst 33342 revealed condensation of the chromatin and nuclear fragmentation. Gel electrophoresis of DNA from HGF/SF-treated cells showed a typical ladder pattern. Cells with a fractional DNA content also increased five-fold in the HGF/SF-treated cultures as analyzed by flow cytometry after propidium iodide staining. These are features typical of apoptosis. Concurrent addition of 12-O-tetradecanoylphorbol 13-acetate (TPA) with HGF/SF augmented the apoptosis induced by the growth factor, while TPA alone caused little death. This enhancement was largely blocked by addition of the specific protein kinase C inhibitor GF 109203X. These results indicate that HGF/SF induced the apoptotic cell death of the Meth A sarcoma cell line and that protein kinase C activation augmented the growth factor-induced apoptosis.

Induction of hepatocyte growth factor/scatter factor by interferon-gamma in human leukemia cells

Induction of hepatocyte growth factor/scatter factor (HGF/SF) may be one of the critical steps in organ regeneration, wound healing, and embryogenesis. We previously reported the production of HGF/SF from various human leukemia cell lines and a high level of the growth factor in blood and bone marrow plasma from patients with various types of leukemia. We determined here the effects of hematopoietic cytokines on HGF/SF production in human leukemia cell lines, KG-1, a myeloid cell line, and RPMI-8226, a B cell line. Interferon (IFN)-gamma remarkably stimulated HGF/SF production in both cell lines at concentrations of more than 0.1 or 1 IU/ml. IFN-alpha and IFN-beta were as effective as IFN-gamma in RPMI-8226 cells, but less than IFN-gamma in KG-1 cells. HGF/SF gene expression in KG-1 cells was also up-regulated by IFN-gamma. Granulocyte colony-stimulating factor (G-CSF), granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-5 and IL-6 had no effect on HGF/SF production in the 2 leukemia cell lines. We also determined the effects of HGF/SF inducers known for human fibroblasts on the growth factor production in leukemia cells. Out of phorbol 12-myristate 13-acetate (PMA), cholera toxin, IL-1 beta, and tumor necrosis factor (TNF)-alpha, the former three were as effective as IFN-gamma in KG-1 cells, but only TNF-alpha stimulated HGF/SF production in RPMI-8226 cells, whose effect was less than those of IFN-alpha, IFN-beta, and IFN-gamma. The effect of IFN-gamma in KG-1 cells was synergistic with that of PMA. In contrast with the effect in leukemia cells, HGF/SF induction by IFN-gamma in human skin fibroblasts was much less than that by PMA or cholera toxin. These results indicated that IFN-gamma is a potent inducer of HGF/SF in human leukemia cells. This finding suggests the presence of a homeostatic control mechanism in liver regeneration and repair: hepatic injury, DNA synthesis inhibition, or apoptosis caused by IFN-gamma is subsequently overcome by cytokine-induced HGF/SF, a potent promoter of liver DNA synthesis.

Interleukin-2-dependent augmentation of the anti-TNP antibody production by sodium butyrate in cultured murine splenic B cells

Previously we found that sodium butyrate (NaBu) markedly enhanced production of the antibody specific for a T-cell-dependent antigen, sheep red blood cells (SRBC) in murine splenocytes (Kishiro, Y., Ueda, K., Fujiwara, M. and Yamamoto, I., Jpn J. Phamacol., 1994 66, 369-376. To gain a better understanding of the target cells for NaBu's action on antibody responses, we have utilized the T-cell-independent antigen, trinitrophenyl-lypopolysaccharide (TNP-LPS) as a stimulant and have examined an effect of NaBu on the anti-TNP antibody production in vitro. NaBu markedly increased the anti-TNP plaque-forming cell (PFC) responses in murine whole splenocytes, but not in murine splenic B cells. Addition of T-cells or the concanavalin A supernatant (CAS) from murine splenocytes to the B cell cultures completely restored the enhancing effect of NaBu. This effect of CAS was totally blocked by an anti-interleukin (IL)-2 antibody and partially by an anti-IL-1 beta or anti-IL-4 antibody. The full enhancing effect of NaBu was also detected when IL-2 was added to the B cell cultures, while IL-2 alone had no stimulatory effect on the control PFC response. IL-1 beta alone significantly stimulated the antibody production and adding NaBu to this IL-1 beta-supplemented culture caused a further increase. Neither IL-4 alone nor NaBu plus IL-4 had any effect on the PFC response. NaBu did not affect the expression of the IL-2 receptor alpha- and beta-chains in B cells stimulated with TNP-LPS. These results suggest that NaBu is an agent that promotes B cell differentiation in vitro in an IL-2-dependent manner.

Nerve growth factor enhances antigen-specific antibody production in ascorbate-stimulated murine splenocytes

In murine splenocytes, a primary antigen-specific antibody response is stimulated by 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G), a stable form of ascorbate, as described in our previous paper. We examined here the effect of nerve growth factor (NGF) on the antigen-specific antibody production in vitro augmented by AA-2G. NGF (> or = 10 ng/ml), which alone had no effect, enhanced the anti-sheep-red-blood-cell (SRBC) antibody response stimulated by AA-2G. The effect of NGF plus AA-2G or AA-2G alone was abrogated by the presence of castanospermine, an alpha-glucosidase inhibitor, suggesting that the active form of AA-2G is ascorbate. The repeated additions; but not one addition, of ascorbate also resulted in a synergism with NGF on the antibody production. These results suggest that NGF might be a cytokine which functions as a regulatory factor for ascorbate-dependent immune responses.

Hepatocyte growth factor--pleiotropic cytokine produced by human leukemia cells

Hepatocyte growth factor (HGF) was identified, purified and molecularly cloned as a potent mitogen for mature rat hepatocytes in primary culture. It is one of the largest cytokines and is composed of disulfide-linked subunits of approximately 60 (heavy chain) and 35 kilodaltons (light chain). Recent observations revealed that HGF is mitogenic to various epithelial cells other than hepatocytes and to endothelial cells, and that it also acts as a motogen, morphogen and tumor-suppressor as well as a mitogen. These various biological activities of HGF are presumably transduced through the same receptor, c-Met, which is a member of the tyrosine kinase receptor family. Although it shows multiple biological activities on cells in culture, HGF is most likely the physiological hepatotrophic factor which triggers liver regeneration. It may also function as a renotrophic and pulmotrophic factor after tissue injury. HGF production in the liver, kidney and lung increases after injury to these organs. An elevated HGF level may act as an inducer of compensatory DNA synthesis. The regulation of HGF production is, therefore, important for the control of organ regeneration. HGF is produced mainly by mesenchymal cells such as fibroblasts and vascular smooth muscle cells. Various types of human leukemia cells also secrete HGF both in vitro and in vivo. Some biological activities of HGF on hematopoietic cells, including co-mitogenic activity on myeloid leukemia cell lines, were recently demonstrated. HGF gene expression and the protein production in leukemia and fibroblast cells are modulated by various cytokines and hormones. Those modulators may indirectly affect organ regeneration and other biological processes by controlling HGF production.

Expression of the protooncogene mdm2 markedly increases in response to carbon tetrachloride but not after partial hepatectomy in contrast to p53

The p53 tumor-suppressor gene is the most commonly altered gene in human cancers. Here we demonstrate that transcripts of the mdm2 gene, which encodes a cellular p53 binding protein, markedly increased in the rat liver within 1 to 3 h, reached a peak at 12 h and returned to the basal level 48 h after the administration of carbon tetrachloride. However, the level of hepatic mdm2 mRNA did not significantly change after partial hepatectomy. This is in contrast to p53 gene expression which increased after either procedure. C-myc transcripts also rapidly increased after the injection of carbon tetrachloride, reaching a maximal level at 3 h. The activity of serum alanine aminotransferase was low within the first 12 h and was maximal 24 h after carbon tetrachloride. These results suggest that the transient hepatic expression of the mdm2 gene prior to the onset of cell death is more likely to reflect events associated with necrosis rather than with cell proliferation.

Enhancement by ascorbic acid 2-glucoside or repeated additions of ascorbate of mitogen-induced IgM and IgG productions by human peripheral blood lymphocytes

In this study, the effect of ascorbic acid 2-glucoside (AA-2G), a stable derivative of ascorbic acid (AsA), or repeated additions of ascorbate on antibody productions by human peripheral blood lymphocytes (PBLs) was examined, and the physiological function of AsA was evaluated. When human PBLs were stimulated with Staphylococcus aureus Cowan I or pokeweed mitogen, AA-2G remarkably increased the numbers of IgM- and IgG-secreting cells which were detected by enzyme-linked immunospot assay. Although a single addition of ascorbate was without effect, the effect of AA-2G was remarkably inhibited by the addition of castanospermine, an alpha-glucosidase inhibitor; and moreover, repeated additions of AsA to the culture medium during the culture period enhanced the response to the same level as did a single addition of AA-2G. These results indicate that AsA has the ability to stimulate the immunoglobulin productions by AA-2G. The phytohemagglutinin-induced proliferative response of PBLs was also stimulated by AA-2G. The intracellular AsA content in PBLs cultured with AA-2G was maintained at relatively high levels during the culture period, whereas the content with a single dose of AsA reached nearly zero by the end of the experiment. These in vitro findings suggest that AA-2G and AsA function as potent immunostimulators of antibody production in humans and that the intracellular AsA content is a key parameter for establishing the immune response of PBLs.

Induction of hepatocyte growth factor in human skin fibroblasts by epidermal growth factor, platelet-derived growth factor and fibroblast growth factor

Hepatocyte growth factor (HGF) is a potent mitogen for rat and human hepatocytes in primary culture and appears to be the physiological hepatotrophic factor that triggers or modulates liver regeneration. Regulation of HGF gene expression and the protein production in human skin fibroblasts was examined. Addition of epidermal growth factor (EGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), acidic fibroblast growth factor (aFGF) and transforming growth factor-alpha (TGF-alpha) to confluent cultures of the cells markedly stimulated HGF secretion from the cells. The stimulating effect of EGF, PDGF and bFGF was further investigated. The effect of all three growth factors was maximal at 3-30 ng/ml and was accompanied by an increase in HGF mRNA levels. The mRNA levels were not elevated at 5 h but were at 10 h or more after addition of EGF. The levels of HGF mRNA in fibroblasts treated with the optimal doses of EGF, PDGF, bFGF, aFGF and TGF-alpha for 24 h were 6, 4, 5, 4 and 5 times that of control cultures incubated in medium only, respectively. The growth factor-induced HGF mRNA expression and HGF secretion was inhibited by addition of TGF-beta 1 or dexamethasone. Pretreatment with a high dose of phorbol 12-myristate 13-acetate (PMA), which causes down-regulation in protein kinase C (PKC) activity and PMA-induced HGF secretion, did not reduce the effects of the growth factors on HGF mRNA expression and HGF secretion, but rather enhanced them.(ABSTRACT TRUNCATED AT 250 WORDS)

Significant amount of hepatocyte growth factor detected in blood and bone marrow plasma of leukaemia patients

Hepatocyte growth factor (HGF) has been known as a versatile functional molecule, and as being involved in the colony formation of haemopoietic progenitor cells. Clinically, an elevated HGF level in the blood has been associated with liver diseases such as fulminant hepatic failure and acute hepatitis. We have found a high level of HGF in blood and bone marrow plasma from patients with various types of leukaemia and lymphoma. In particular, 21/31 acute myeloblastic leukaemia (AML) patients showed a significant level of HGF (> 0.40 ng/ml) in their blood or bone marrow plasma. The mean value of HGF in the plasma of AML patients was 2.03 ng/ml, which was higher than that in the serum of patients with acute hepatitis. This demonstrates, for the first time, evidence of frequent association of increased levels of HGF in non-lymphocytic leukaemias, though its significance in the disease remains unknown.

Production of hepatocyte growth factor by human haematopoietic cell lines

Hepatocyte growth factor (HGF) is a multi-functional molecule characterized as a mitogen, a motogen, a morphogen and a tumour suppressor. Little is known about cell types which produce HGF, so we analysed HGF production from cultured cell lines of haematopoietic cell lineage. A total of 138 human leukemia and virus-transformed cell lines were studied and the levels of HGF were measured by ELISA. A significant amount of HGF was detected in a variety of cell lines, including one T, four B, five non-T non-B, eight myeloid one erythroid and two EBV-transformed B cell lines. The amount of HGF spontaneously produced by three of the myeloid cell lines, KCL-22 (33.48 ng/ml), KG-1A (26.21 ng/ml), and KG-1 (18.81 ng/ml), is comparable to the amount produced by human embryonic lung fibroblast cells, known as high HGF-producers. Biological assays together with Western blot analyses verified that the immunoreactive HGF detected in the culture supernatant of haematopoietic cell lines had the same properties as authentic HGF. Moreover, HGF mRNA was detected in high HGF producers by Northern blot analysis. Our findings that lymphoid and myeloid cells function as a source of HGF may provide significant evidence for the involvement of haematopoietic cells in HGF-related morphogenesis and cell growth.

Increase in production of hepatocyte growth factor by human embryonic lung fibroblasts in the process of aging in culture

It was determined whether human hepatocyte growth factor (hHGF)-producing ability would change in the human embryonic lung fibroblast cell strains (MRC-5 and IMR-90) until the cells senesced in culture. The effects of phorbol 12-myristate 13-acetate (PMA), dexamethasone, and transforming growth factor-beta 1 (TGF-beta 1) on hHGF production were also studied in these cell strains. For stimulation of DNA synthesis of adult rat hepatocytes in primary culture, hHGF secreted by MRC-5 cells at 39.9 and 69.8 population doubling levels (PDLs) showed almost the same activity as recombinant hHGF. Secretion of hHGF by MRC-5 cells increased about threefold between 37.3 and 67.8 PDLs. IMR-90 cells also showed about a threefold increase in hHGF secretion with increased passage from 37.8 to 66.0 PDL. Both cell strains showed almost the same ratio of hHGF amount in the cell extracts to that secreted into the medium around 40 and 70 PDLs. Northern blot analysis showed that the transcriptional level of the hHGF gene in MRC-5 cells increased about three-fold from 42.0 to 73.6 PDL in culture. These findings indicated that hHGF production increased in both cell strains with aging in culture. Production of hHGF in both cell strains was remarkably stimulated by treatment with 10 nM PMA. On the other hand, hHGF production in both cell strains was slightly suppressed by treatment with 1 microM dexamethasone. TGF-beta at a concentration of 5 ng/ml prominently inhibited hHGF production in both cell strains. The response of both cell strains to these regulators for hHGF production was almost the same around 40 and 70 PDLs in culture.

Expression of hepatocyte growth factor is up-regulated through activation of a cAMP-mediated pathway

Hepatocyte growth factor (HGF) is a multifunctional cytokine with mitogenic, motogenic, morphogenic, and tumor-suppressing activities. Despite the broad spectrum of its biological activities, HGF is most likely the physiological hepatotrophic factor that triggers or modulates liver regeneration. Regulatory mechanisms for HGF production are crucial for understanding the control of liver regeneration. We previously reported that HGF production by human skin fibroblasts is stimulated by a protein kinase C (PKC)-mediated pathway. We determined here whether gene expression and production of HGF in human skin fibroblasts can be induced via activation of a cAMP-mediated pathway. HGF secretion by the cells was markedly stimulated by the cAMP-elevating agents, forskolin, cholera toxin, prostaglandin E2 (PGE2), and 3-isobutyl-1-methylxanthine, as well as by the membrane-permeable cAMP analogues, 8-bromo-cAMP and dibutyryl cAMP. The dose-response curves of induction of HGF secretion by cholera toxin and forskolin were nearly parallel with those of the intracellular cAMP levels. HGF mRNA levels did not significantly increase at 5 and 10 h, but increased considerably 15 h or more after the addition of cholera toxin. Forskolin, 8-bromo-cAMP, and PGE2 also caused appreciable up-regulation of HGF gene expression with a similar time course. Although human skin fibroblasts of various origins secreted variable amounts of HGF, the cAMP-elevating agents and the cAMP analogues caused a very marked increase in HGF production in all of them. The agents also enhanced highly active HGF secretion by MRC-5 human embryonic lung fibroblasts. Dexamethasone and transforming growth factor-beta 1, which inhibit PKC-mediated HGF secretion, down-regulated HGF mRNA expression and HGF production in the cells treated with the cAMP-elevating agents and the cAMP analogues. These results indicate that HGF expression in human skin fibroblasts is stimulated by activation of a cAMP-mediated pathway.

[Effects of cisplatin, carboplatin, etoposide and human hepatocyte growth factor on the colony formation of four human liver cancer cell lines]

Antitumor activity of cisplatin, carboplatin, etoposide, or human hepatocyte growth factor (hHGF), was compared by examining the colony formation ability of four liver cancer cell lines (PLC/PRF/5 and HuH-7, hepatocellular carcinoma; HuH-6 and HepG2, hepatoblastoma). Antitumor activity was evaluated from the drug concentration causing 50% cell death by a colony assay. PLC/PRF/5 cells were most effectively killed by cisplatin and etoposide, HuH-7 cells by cisplatin and carboplatin, HuH-6 cells by etoposide, and Hep G2 cells by cisplatin. These results indicate that among four liver cancer cell lines, the three were the most sensitive to cisplatin, the two were to etoposide and the only one cell line was to carboplatin. There was no significant relationship between each drug and types of liver cancer. Combined treatment with cisplatin (0.01-1.0 microgram/ml) and etoposide (0.1 microgram/ml) showed synergistic cytotoxic effects on the colony formation of PLC/PRF/5 cells, while combination of carboplatin (0.01-0.1 microgram/ml) and etoposide (0.1 microgram/ml) caused subadditive cytotoxic effects. hHGF stimulated the colony formation of HuH-6 cells, while it inhibited that of Hep G2 cells. The treatment of HuH-6 with cisplatin and hHGF showed a higher cell survival percentage compared with the treatment with cisplatin alone. On the other hand, cell survival of Hep G2 cells was remarkably decreased by the combined treatment with cisplatin and hHGF.

Stimulation of DNA synthesis in skin fibroblasts by human hepatocyte growth factor/scatter factor

The effect of hepatocyte growth factor/scatter factor (HGF/SF) on the proliferation of human skin fibroblasts was examined. At concentrations above 1.0 ng/ml, both native and recombinant human HGF/SF stimulated the DNA synthesis determined by [3H]thymidine incorporation, which was completely inhibited by an anti-human HGF/SF monoclonal antibody. The maximal DNA synthesis in the treated cells was nearly twice that in untreated cells. HGF/SF also caused an increase in the labelling index, DNA content and cell number. The effect of HGF/SF was more than additive to the maximal effect of insulin and epidermal growth factor, other mitogens for the fibroblasts. These results indicate that human skin fibroblasts are sensitive to the mitogenic action of HGF/SF.

TGF-beta is a potent inhibitor of hepatocyte growth factor secretion by human fibroblasts

Transforming growth factor-beta 1 (TGF-beta 1) inhibited secretion of human hepatocyte growth factor (hHGF), which is also known as scatter factor or fibroblast-derived tumor cytotoxic factor, by MRC-5 cells. The effect was detectable at as little as 10 pg/ml and was more potent than that of dexamethasone. Complete inhibition was observed after 12 h in the presence of 5 ng/ml of TGF-beta 1. Phorbol 12-myristate 13-acetate-induced secretion of hHGF from human skin fibroblasts was also suppressed by TGF-beta 1. TGF-beta 2 inhibited hHGF secretion by MRC-5 cells to the same extent as TGF-beta 1, but other growth factors such as epidermal growth factor and acidic and basic fibroblast growth factors had only a slight or null inhibitory effect.

Phorbol ester-induced secretion of human hepatocyte growth factor by human skin fibroblasts and its inhibition by dexamethasone

Human skin fibroblasts secreted a certain amount of human hepatocyte growth factor (hHGF), as determined by an enzyme-linked immunosorbent assay for hHGF. This hHGF secretion was remarkably stimulated by protein kinase C (PKC)-activating phorbol esters, which was inhibited by the simultaneous addition of dexamethasone. Pretreatment with phorbol 12-myristate 13-acetate (PMA) caused a down-regulation in hHGF secretion. hHGF secreted by the PMA-treated cells showed a potent hepatocyte growth-promoting activity which was neutralized by an anti-hHGF antiserum. These results indicate both that PMA-treated human skin fibroblasts produce biologically active hHGF and the possible involvement of PKC activation in this process.

Purification and characterization of a mouse hepatocyte growth-stimulating factor from the liver of carbon tetrachloride-treated mice

Mouse hepatocyte growth-stimulating factor (mHGSF), which increased markedly in the liver of carbon tetrachloride-treated mice, was purified 275,000-fold with 21% yield from extracts of the injured liver. The purification involves ammonium sulfate precipitation and chromatography on Affi-Gel Blue, heparin-Sepharose, and S-Sepharose. The purified factor migrated as a major band of 76,000 daltons under nonreducing conditions and two bands of 62,000 and 31,000 daltons under reduced conditions. A dose-response of this growth factor for stimulation of deoxyribonucleic acid synthesis in cultured rat hepatocytes and its maximal effects were similar to those of human hepatocyte growth factor (hHGF), which we previously purified from the plasma of patients with fulminant hepatic failure (E. Gohda et al., J. Clin. Invest., 81, 414-419 (1988)). The effect of mHGSF was additive to the maximal effect of epidermal growth factor and was synergistic with that of insulin or acidic fibroblast growth factor, but was neither additive nor synergistic with the maximal effect of hHGF. mHGSF, like hHGF, was sensitive to heat and trypsin treatments and to reduction by dithiothreitol. This factor did not react with an anti-hHGF antiserum. These results indicate that mHGSF is a hHGF-like factor, but it is immunologically different from hHGF.

Characterization of a mouse hepatocyte growth-stimulating factor in serum of mice treated with carbon tetrachloride

The physicochemical and biological properties of a mouse hepatocyte growth-stimulating factor (mHGSF), whose amount in mouse serum increased markedly 24 h after carbon tetrachloride administration (E. Gohda et al., Life Sci. 46, 1801 (1990)), were examined. This factor was a heat-labile protein with a molecular weight of 75000. Its activity was sensitive to disulfide reduction. Maximal stimulation of deoxyribonucleic acid synthesis in cultured rat hepatocytes by this factor was greater than that by acidic fibroblast growth factor (acidic FGF) or mouse epidermal growth factor (EGF) and was comparable to maximal stimulation by human hepatocyte growth factor (hHGF), a heterodimer with a molecular weight of about 85000. The effect of mHGSF was additive to the maximal effects of acidic FGF and EGF and was synergistic with the maximal effect of insulin, but was neither additive nor synergistic with the maximal effect of hHGF. The mHGSF activity was not inhibited by a neutralizing anti-hHGF antiserum, which recognizes nonreduced hHGF but not reduced heavy and light chains of hHGF. mHGSF did not show any cross-reactivity to anti-hHGF monoclonal and/or polyclonal antibodies as measured by an enzyme-linked immunosorbent assay for hHGF. These results suggest that mHGSF is a hHGF-like factor with some structural difference from hHGF.

Human hepatocyte growth factor stimulates the growth of HUH-6 clone 5 human hepatoblastoma cells

The effects of human hepatocyte growth factor (hHGF), a potent mitogen for rat and human hepatocytes in primary culture, on proliferation of human hepatoma and hepatoblastoma cells were examined. Out of five cell lines; HLE, HuH-6 clone 5, HuH-7, PLC/PRF/5, and Hep G2, only HuH-6 Clone 5 cells were stimulated by recombinant hHGF. Both native and recombinant hHGFs caused dose-dependent increases in cell number and DNA synthesis of cells. This stimulation was strongly inhibited by anti-hHGF monoclonal antibody.

Human hepatocyte growth factor in blood of patients with fulminant hepatic failure. Basic aspects

Human hepatocyte growth factor (hHGF) was purified from the plasma of six patients with fulminant hepatic failure due to hepatitis B in two and non-A, non-B hepatitis in four. The purified hHGF from each patient contained two major protein bands having molecular weights of 79,000 and 86,000 and several minor bands having molecular weights between 76,000 and 92,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis performed under nonreduced conditions. After reduction with 2-mercaptoethanol, three major bands having molecular weights of 58,000, 34,500, and 31,500 were evident. In addition, a band having a molecular weight of 21,000 was detected. hHGF activity was destroyed by its reduction. The hHGF purified from patients demonstrated a dose response in terms of an increase in DNA synthesis using cultured hepatocytes. The hHGF concentration in the plasma of the patients with grade III-IV hepatic coma was calculated to be in the range of 1.8-3.0 nM. Finally the heavy chain of hHGF was not recognized by an anti-human albumin antibody, indicating that hHGF is not biliprotein, an albumin-bilirubin complex, that has been reported to be a putative liver growth factor.

Human hepatocyte growth factor in blood of patients with fulminant hepatic failure. I. Clinical aspects

The levels of human hepatocyte growth factor (hHGF) in sera obtained from patients with various liver diseases were determined using adult rat hepatocytes maintained in primary culture. The mean hHGF activity for 22 patients with fulminant hepatic failure was about nine times greater than that found in normal human serum. The increase in serum hHGF activity seen in two patients with "acute-on-chronic" hepatitis was similar to that found in patients with fulminant hepatic failure. The serum level of hHGF from patients with acute hepatitis is related to the stage of their illness. The average value for 31 patients was about three times that of normal human serum. In some patients, the time course for the increase in serum hHGF activity was similar to that demonstrated for alpha-fetoprotein. The mean hHGF activity in serum for the 33 patients with chronic hepatitis and from 25 patients with liver cirrhosis was increased also compared with that of normal human serum. In addition, serum hHGF activity in three of seven patients studied after partial hepatectomy for a space-occupying lesion of the liver was increased. These data suggest that the increase in serum hHGF activity present in patients with various liver diseases reflects a self-defense mechanism that is involved in the process of liver cell regeneration.

Identification of the N-terminal residue of the heavy chain of both native and recombinant human hepatocyte growth factor

The N-terminal amino acid of the heavy chain of native (purified from human plasma) and recombinant human hepatocyte growth factor (hHGF) was determined by analyses of amino acid composition and sequence of peptide fragments derived by enzymatic cleavage, peptide mapping, and fast atom bombardment mass spectrometry. Our results indicate that the N-terminal amino acid of the heavy chain of hHGF, both native and recombinant, is pyroglutamate, derived from glutamine at the 32nd residue from the initiation methionine.

Levels of the human hepatocyte growth factor in serum of patients with various liver diseases determined by an enzyme-linked immunosorbent assay

We have found a hepatotrophic factor in plasma or sera of patients with fulminant hepatic failure and have purified human hepatocyte growth factor from plasma of these patients. In this study we developed an enzyme-linked immunosorbent assay with high specificity and sensitivity for human hepatocyte growth factor in human serum. This assay for serum human hepatocyte growth factor is a sandwich method consisting of three steps. The standard curve for human hepatocyte growth factor appeared to be linear in the range of 0.20 to 12.50 ng purified human hepatocyte growth factor/ml (2.35 to 147 pmol/L). The assay took about 4 hr. Serum human hepatocyte growth factor values in patients with fulminant hepatic failure measured by enzyme-linked immunosorbent assay showed a strong positive correlation with that by bioassay using rat hepatocytes in primary culture. The mean value of serum human hepatocyte growth factor for 30 normal subjects was 0.24 +/- 0.12 (S.D.) ng/ml; that for 23 patients with fulminant hepatic failure was 8.06 +/- 1.76 (S.E.M.) ng/ml- greater than 30 times greater than the mean value for normal subjects. Serum human hepatocyte growth factor levels in patients with acute hepatitis, chronic hepatitis and cirrhosis were found to be slightly higher than those in normal subjects, but only the increase in serum human hepatocyte growth factor of acute hepatitis patients was statistically significant. The enzyme-linked immunosorbent assay for serum human hepatocyte growth factor should prove useful for serum human hepatocyte growth factor level measurement in patients with various liver diseases.

Dibutyrylcytidine 3',5'-cyclic monophosphate stimulates neurite outgrowth in rat pheochromocytoma PC12

Dibutyrylcytidine 3',5'-cyclic monophosphate (Bt2cCMP) stimulated neurite outgrowth in rat pheochromocytoma PC12 cells in a dose-dependent manner at the dose range from 0.5 mM to 6 mM. About 25% of the cells had neurites in response to 6 mM Bt2cCMP. In contrast with the effect of nerve growth factor (NGF) which increased the percentage of cells with neurites gradually during a 6-day culture period, the stimulating effect of Bt2cCMP reached a plateau 2 days after plating. Staurosporine inhibited the neurite outgrowth induced by NGF, but not that by Bt2cCMP. These results suggest that Bt2cCMP stimulates neuronal differentiation by a mechanism different from that by NGF.

Biological and immunological properties of human hepatocyte growth factor from plasma of patients with fulminant hepatic failure

We have recently purified human hepatocyte growth factor (hHGF), a heterodimer with molecular weight of about 83,000, from plasma of patients with fulminant hepatic failure (Gohda, E. et al., J. Clin. Invest. 81, 414-419, 1988). Biological and immunological properties of hHGF were examined. Out of the well-known growth factors tested, only epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) stimulated DNA synthesis of adult rat hepatocytes in primary culture. hHGF enhanced the DNA synthesis at less than one-tenth of the molar concentrations of EGF and TGF-alpha. Half-maximal stimulations by hHGF, EGF and TGF-alpha were observed at 30, 400 and 900 pM, respectively. Maximal stimulation by TGF-alpha, however, was greater than those caused by hHGF and EGF. The effect of hHGF was additive with the maximal effects of EGF and TGF-alpha. Anti-hHGF antiserum was prepared in a rabbit by injecting with purified hHGF. This antiserum recognized nonreduced hHGF, but not reduced hHGF. The antiserum for hHGF did not inhibit growth-promoting activity of EGF, that was neutralized by incubation with anti-EGF antiserum. The activity of hHGF was completely inhibited by anti-hHGF antiserum, but not by anti-EGF antiserum. hHGF did not show any cross-reactivity to anti-EGF antiserum as measured by enzyme immunoassay for EGF. Thus, biological and immunological properties of hHGF are different from those of EGF and TGF-alpha.

Hepatotrophic growth factor in blood of mice treated with carbon tetrachloride

The presence of a human hepatocyte growth factor (hHGF)-like DNA-synthesis promoter in platelet-poor serum of mice with liver injury was examined. Activity of the serum for stimulating DNA synthesis in cultured rat hepatocytes was low in untreated or vehicle-treated mice, but markedly increased 24 h after carbon tetrachloride administration and then dropped to normal levels prior to the peak of liver DNA synthesis. The effect of the serum was additive with the maximal effects of mouse and human epidermal growth factors, but not with that of hHGF. The growth-stimulating factor in the mouse serum, like hHGF, had affinity for heparin and was heat-labile. These results indicate that the level of a serum hHGF-like hepatocyte growth factor increased in mice treated with carbon tetrachloride prior to liver regeneration.

Inhibition of DNA synthesis of adult rat hepatocytes in primary culture by dibutyrylcytidine 3', 5'-cyclic monophosphate

The effect of dibutyrylcytidine 3',5'-cyclic monophosphate (Bt2cCMP) on DNA synthesis of adult rat hepatocytes in primary culture was examined. Bt2cCMP caused dose-dependent inhibition of the DNA syntheses stimulated by various growth factors including human hepatocyte growth factor (hHGF). Dibutyryladenosine 3',5'-cyclic monophosphate (Bt2cAMP) inhibited the DNA synthesis more effectively than Bt2cCMP, but dibutyrylguanosine 3',5'-cyclic monophosphate (Bt2cGMP) and n-butyrate had a slight or null inhibitory effect. When added at the onset of DNA synthesis, Bt2cAMP was much less effective, but Bt2cCMP was still effective. Thus Bt2cCMP is able to inhibit growth factor-stimulated hepatocyte proliferation.

Clinical significance of human hepatocyte growth factor in blood from patients with fulminant hepatic failure

We have recently found the presence of human hepatocyte growth factor in sera of patients with fulminant hepatic failure and have purified human hepatocyte growth factor from plasma of a patient with fulminant hepatic failure. In this paper, we report the clinical significance of human hepatocyte growth factor in blood from patients with fulminant hepatic failure. The effect of sera or plasma from 17 patients with fulminant hepatic failure on liver cell growth was examined by use of adult rat hepatocytes in primary cultures. Sera or plasma from 16 of the 17 patients with fulminant hepatic failure stimulated DNA synthesis in hepatocytes more effectively than normal human serum. The mean growth-promoting activity for the 17 patients with fulminant hepatic failure was about 16 times higher than that obtained for normal human serum. This growth-promoting activity of the patients' blood was not related to sex, age, clinical outcome of the patients or type of fulminant hepatic failure, but was intimately related to the clinical grade of hepatic coma. Sera or plasma with Grade III and IV coma showed stimulatory activity on DNA synthesis more markedly than sera or plasma from patients with coma of less than Grade II. In the surviving group, this activity decreased as the hepatic coma of patients improved. In fact, this activity of sera from patients at the recovery stage showed no significant increase compared with that of normal human serum. In the group of terminal patients, this activity increased as the coma developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and partial characterization of hepatocyte growth factor from plasma of a patient with fulminant hepatic failure

Human hepatocyte growth factor (hHGF) has been purified approximately 209,000-fold with 18% yield from plasma of a patient with fulminant hepatic failure. The purification involves heat treatment of plasma, ammonium sulfate precipitation, and chromatography on Affi-Gel Blue, heparin-Sepharose, and hydroxylapatite. Purified hHGF shows several bands with molecular weights between 76,000 and 92,000. Each band shows growth-stimulating activity on cultured hepatocytes which is proportional to the intensity of the band. After reduction of the sample with 2-mercaptoethanol, SDS-PAGE yields two chains with molecular weights of 31,500-34,500 and 54,000-65,000. The effect of hHGF on DNA synthesis by hepatocytes is half-maximal at 3.5 ng/ml. hHGF stimulates proliferation of cultured hepatocytes more effectively than human epidermal growth factor (hEGF) or insulin, and the effect of hHGF is additive or synergistic with the maximal effects of hEGF and insulin. These results suggest that hHGF is a new growth factor which is different from hEGF.

Effect of histamine H2-receptor antagonists on DNA synthesis in adult rat hepatocytes in primary culture. Cimetidine enhanced hepatocytes proliferation stimulated with insulin and epidermal growth factor

The effects of three of the most widely used histamine H2-receptor antagonists, cimetidine, ranitidine and famotidine, on liver cell growth were studied in vitro using adult rat hepatocytes in primary culture, because these antagonists are commonly given to patients with hepatic cirrhosis or fulminant hepatic failure for protection against peptic ulcers and gastrointestinal hemorrhage. At their clinically effective concentrations in the blood (0.5-5 micrograms/ml cimetidine, 0.25-2.5 micrograms/ml ranitidine and 0.05-0.5 microgram/ml famotidine), these three antagonists did not have any effect on replicative DNA synthesis either in the presence or absence of insulin plus epidermal growth factor (EGF). However, unexpectedly DNA synthesis stimulated by insulin and EGF was found to be enhanced by 0.05-0.5 mg/ml cimetidine, although it was unaffected or inhibited by ranitidine and famotidine at the concentrations tested. Cimetidine caused maximal enhancement of 1.5-2 times the control level of DNA synthesis at a concentration of 0.25 mg/ml. Cimetidine also had an enhancing effect at submaximal concentrations of insulin and EGF, but neither cimetidine nor the other antagonists had any stimulatory effect on DNA synthesis in the absence of insulin plus EGF. This enhancement of DNA synthesis by cimetidine resulted in significant increase in the total DNA content of the hepatocytes in culture. Under the conditions used, cimetidine had the lowest toxicity of these three antagonists and ranitidine the highest, as judged from data on DNA synthesis and the total protein content of cultured hepatocytes, leakage of aminotransferases from the cells and morphological observations.

Human hepatocyte growth factor in plasma from patients with fulminant hepatic failure

Plasma from patients with fulminant hepatic failure obtained during plasma exchange therapy, like their serum, demonstrated marked stimulatory activity on DNA synthesis in cultured rat hepatocytes. Heat treatment at 56 degrees C for 30 min did not affect this activity of the plasma, but reduced that of the serum. This growth-promoting activity was confirmed by showing that the patients' serum and plasma increased the labeling index with [3H]thymidine and the total number of nuclei in hepatocyte cultures. The activity of pooled active fractions obtained by gel filtration of the heated plasma was lost completely on heat treatment at 80 degrees C for 10 min or on treatment with trypsin or chymotrypsin, which suggests that it was due to a protein. The human hepatocyte growth factor was purified about 600-fold from heated plasma of a patient by ammonium sulfate precipitation and chromatographies on Affi-Gel Blue and hydroxylapatite. The maximum effect of this partially purified factor on DNA synthesis in cultured hepatocytes was greater than that of epidermal growth factor. The molecular weight of the hepatocyte growth factor was about 85,000 as determined by SDS-PAGE.

Degradation of [125I]iodoglucagon by normal rat plasma in radioimmunoassay mixture containing aprotinin and its prevention by p-chloromercuriphenyl sulfonate and leupeptin

Degradation of [125I]iodoglucagon during RIA of glucagon would result in erroneously high values for immunoreactive glucagon (IRG). Normal rat plasma was found to have high activity for glucagon degradation that was not suppressed by the aprotinin and EDTA routinely added to the RIA system. About 30% of the added radioactive glucagon was degraded during RIA in assay mixture at pH 7.4 containing 0.2 ml normal rat plasma, and the IRG value was calculated to be 150-180 pg/ml plasma. The degradation was completely inhibited by addition of 2 mM p-chloromercuriphenyl sulfonate (PCMS) plus 0.25 mM leupeptin as protease inhibitors, and in their presence the IRG value was about 80 pg/ml. The glucagon-degrading activity was about half as much in assay mixture at pH 8.8 as in that at pH 7.4, but the degradation still affected the accuracy of IRG values. When rat plasma was incubated with [125I]iodoglucagon in the assay conditions used for RIA and then subjected to Bio-Gel P-6 filtration, three new peaks of radioactivity were found in low mol wt fractions, with decrease in the peak corresponding to [125I]iodoglucagon, whereas on similar treatment in the presence of PCMS and leupeptin all the radioactivity was recovered in the glucagon fraction. The average recoveries of authentic glucagon as IRG in the absence and presence of the inhibitors were less than 60% and more than 90%, respectively. These findings indicate that determination of plasma IRG in rats by RIA with assay mixture containing aprotinin gives spuriously high values owing to degradation of the radiotracer, and that PCMS and leupeptin should be added to the sample and assay mixture to prevent this degradation.

Immunohistochemical studies with a monoclonal antibody on the distribution of phosphophoryn in predentin and dentin

A monoclonal antibody was raised against phosphophoryn, a unique noncollagenous phosphoprotein in dentin. Mouse myeloma NS-I cells were fused with spleen cells obtained from BALB/c mice immunized with phosphophoryn from fetal calf tooth germs. Mice inoculated with the hybridoma produced ascites fluid containing the antibody and this reacted only with a band of phosphophoryn transblotted from polyacrylamide gel. Immunohistochemical studies with the antibody showed that phosphophoryn was present in odontoblasts, odontoblastic processes and dentin, but not in the matrix of predentin, and that the phosphophoryn content of the dentin layer was high at and around the predentin-dentin junction and gradually decreased toward the enamel layer. The area corresponding to mantle dentin was not stained with the antibody.

Increased activities of liver cathepsins T and D in carbon tetrachloride-treated rats

Changes in activities of a new proteinase cathepsin T as well as some other lysosomal acid proteinases and hydrolases were examined in liver homogenate from rats treated with a single hepatotoxic dose of carbon tetrachloride. The most striking changes were several-fold increases of liver cathepsin T and D activities over their levels in untreated rats 3 days after administration of the agent to rats. Increase of cathepsin T was greater than that of cathepsin D at all doses of the hepatotoxin examined. The activities of N alpha-benzoyl-DL-arginine 2-naphthylamide hydrolase, acid phosphatase, beta-galactosidase and beta-glucuronidase in poisoned rat liver were unchanged or only slightly increased. Cathepsin T and D activities were less enhanced in mitochondrial lysosomal fractions than in the homogenate, and were greatly elevated in the supernatant fractions of liver from the treated rats. As judged from the molecular weights, the elevated activities of cathepsins T and D in the treated rat liver could be attributable to the two cathepsins themselves and not to other proteinases. Administration to rats of other hepatotoxic agents, thioacetamide and dimethylnitrosamine, also induced the elevation of the two cathepsin activities in liver, but on partial hepatectomy the activities of liver cathepsins T and D did not show such marked increases. Nonparenchymal liver cell fractions were responsible for almost all the increased activities of liver cathepsins T and D. It is possible that cathepsins T and D play a role in the heterolytic breakdown of hepatocyte molecules following CCl4 poisoning.

Immunoreactive glucagon in the vascular walls of the rat

We detected immunohistochemically immunoreactive glucagon (IRG) in the smooth muscle of blood vessels and the myoepithelial cell of sweat glands of rats using two antisera against pancreatic glucagon; OAL-123 and 30K. The content of IRG in the blood vessels was found to be 320-1, 270 pg per g wet tissue weight. Filtration of the extracted IRG through a Bio Gel P-30 column yielded a single peak of IRG at 3,500 daltons, the same elution volume of pancreatic glucagon. These findings suggest that the blood vessels of the rats is one of the extrapancreatic sources of IRG in plasma, although physiological role of the IRG is not known.

Glucagon degradation in fraction of big plasma glucagon in rats treated with carbon tetrachloride

When whole plasma obtained from rats given carbon tetrachloride was applied to a column of Bio Gel P-30, P-150 or P-300, a large molecular form of immunoreactive glucagon (IRG), so called "big plasma glucagon" (BPG), was eluted in the void volume. Glucagon degrading activity, measured under the same conditions as for radioimmunoassay of IRG, was eluted in parallel with IRG. Since standard assay mixture containing aprotinin was used for the measurement of IRG, this degradation of glucagon might be due to an enzyme(s) other than serine proteinases. p-Hydroxymercuribenzoate depressed glucagon degradation and IRG in the BPG fractions to 20% and 30% of the control values, respectively. Other inhibitors of thiol proteinases, such as N-ethylmaleimide and leupeptin, also decreased the values for both glucagon degradation and IRG to a similar extent. However, phenylmethylsulfonyl fluoride and pepstatin had little or no effect on these values. On filtration of plasma from carbon tetrachloride-treated rats on a column of Bio Gel A-1.5m, IRG peaks between 600k and 1,200k daltons were obtained and glucagon degrading activity was again eluted with IRG. When p-chloromercuriphenyl sulfonate and N-ethylmaleimide were added to the elution buffer and assay mixtures, the glucagon degrading activity was almost completely inhibited and the values for IRG between 600k and 1,200k daltons were decreased to less than 10% of those of the control. These results indicate that more than 90% of the IRG in the fractions of BPG obtained from carbon tetrachloride-treated rats could be accounted for entirely by the degradation of immunoreactive 125I-glucagon by plasma proteinases, probably thiol proteinases. Thus we conclude that some proteinases are still active in the radioimmunoassay system of glucagon which is widely used at present, and lead apparently higher glucagon values owing to degradation of 125I-glucagon.