Increase In Hepatocyte Growth Factor Research Articles

Activation of Hepatocyte Growth Factor/MET Signaling as a Mechanism of Acquired Resistance to a Novel YAP1/TEAD Small Molecule Inhibitor.

Many tumor types harbor alterations in the Hippo pathway, including mesothelioma, where a high percentage of cases are considered YAP1/TEAD dependent. Identification of autopalmitoylation sites in the hydrophobic palmitate pocket of TEADs, which may be necessary for YAP1 protein interactions, has enabled modern drug discovery platforms to generate compounds that allosterically inhibit YAP1/TEAD complex formation and transcriptional activity. We report the discovery and characterization of a novel YAP1/TEAD inhibitor MRK-A from an aryl ether chemical series demonstrating potent and specific inhibition of YAP1/TEAD activity. In vivo, MRK-A showed a favorable tolerability profile in mice and demonstrated pharmacokinetics suitable for twice daily oral dosing in preclinical efficacy studies. Importantly, monotherapeutic targeting of YAP1/TEAD in preclinical models generated regressions in a mesothelioma CDX model; however, rapid resistance to therapy was observed. RNA-sequencing of resistant tumors revealed mRNA expression changes correlated with the resistance state and a marked increase of hepatocyte growth factor (HGF) expression. In vitro, exogenous HGF was able to fully rescue cytostasis induced by MRK-A in mesothelioma cell lines. In addition, co-administration of small molecule inhibitors of the MET receptor tyrosine kinase suppressed the resistance generating effect of HGF on MRK-A induced growth inhibition. In this work, we report the structure and characterization of MRK-A, demonstrating potent and specific inhibition of YAP1/TAZ-TEAD-mediated transcriptional responses, with potential implications for treating malignancies driven by altered Hippo signaling, including factors resulting in acquired drug resistance.

Chemotherapy-induced PDL-1 expression in cancer-associated fibroblasts promotes chemoresistance in NSCLC

ObjectivesA cure for cancer is out of reach for most patients due to chemoresistance. Cancer-associated fibroblasts (CAFs) play a vital role in cancer chemoresistance, but detailed understanding of the process particularly in chemoresistant lung cancer is lacking. In this study, we investigated programmed death-ligand 1 (PDL-1) as a potential biomarker for CAF-induced chemoresistance and evaluated its role and the underlying mechanisms of chemoresistance in non-small cell lung cancer (NSCLC). Materials and MethodsA systemic search of gene expression profiles of multiple tissues in NSCLC was carried out to determine the expression intensities of traditional fibroblast biomarkers and CAF-secreted protumorigenic cytokines. PDL-1 expression in CAFs was analyzed by ELISA, Western blotting, and flow cytometry. Human cytokine array was used to identify specific cytokines secreted from CAFs. Role of PDL-1 in NSCLC chemoresistance was assessed using CRISPR/Cas9 knockdown and various functional assays including MTT, cell invasion, sphere formation, and cell apoptosis. In vivo experiments were conducted using a co-implantation xenograft mouse model with live cell imaging and immunohistochemistry. ResultsWe demonstrated that chemotherapy-stimulated CAFs promoted tumorigenic and stem cell-like properties of NSCLC cells, which contribute to their chemoresistance. Subsequently, we revealed that PDL-1 expression is upregulated in chemotherapy-treated CAFs and is associated with poor prognosis. Silencing PDL-1 expression suppressed CAFs’ ability to promote stem cell-like properties and invasiveness of lung cancer cells, favoring chemoresistance. Mechanistically, an upregulation of PDL-1 in chemotherapy-treated CAFs led to an increase in hepatocyte growth factor (HGF) secretion, which stimulates cancer progression, cell invasion, and stemness of lung cancer cells, while inhibiting apoptosis. ConclusionOur results show that PDL-1-positive CAFs modulate stem cell-like properties of NSCLC cells by secreting elevated HGF, thereby promoting chemoresistance. Our finding supports PDL-1 in CAFs as a chemotherapy response biomarker and as a drug delivery and therapeutic target for chemoresistant NSCLC.

Plasma-Based Bioinks for Extrusion Bioprinting of Advanced Dressings.

Extrusion bioprinting based on the development of novel bioinks offers the possibility of manufacturing clinically useful tools for wound management. In this study, we show the rheological properties and printability outcomes of two advanced dressings based on platelet-rich plasma (PRP) and platelet-poor plasma (PPP) blended with alginate and loaded with dermal fibroblasts. Measurements taken at 1 h, 4 days, and 18 days showed that both the PRP- and PPP-based dressings retain plasma and platelet proteins, which led to the upregulation of angiogenic and immunomodulatory proteins by embedded fibroblasts (e.g., an up to 69-fold increase in vascular endothelial growth factor (VEGF), an up to 188-fold increase in monocyte chemotactic protein 1 (MCP-1), and an up to 456-fold increase in hepatocyte growth factor (HGF) 18 days after printing). Conditioned media harvested from both PRP and PPP constructs stimulated the proliferation of human umbilical vein endothelial cells (HUVECs), whereas only those from PRP dressings stimulated HUVEC migration, which correlated with the VEGF/MCP-1 and VEGF/HGF ratios. Similarly, the advanced dressings increased the level of interleukin-8 and led to a four-fold change in the level of extracellular matrix protein 1. These findings suggest that careful selection of plasma formulations to fabricate wound dressings can enable regulation of the molecular composition of the microenvironment, as well as paracrine interactions, thereby improving the clinical potential of dressings and providing the possibility to tailor each composition to specific wound types and healing stages.

MiRNA-486 regulates angiogenic activity and survival of mesenchymal stem cells under hypoxia through modulating Akt signal

MicroRNA-486 (miR-486) was first identified from human fetal liver cDNA library and validated as a regulator of hematopoiesis. Its roles in regulating the biological function of bone marrow-derived mesnechymal stem cells (BM-MSCs) under hypoxia have not been explored yet. In this study, we demonstrated that exposure to hypoxia upregulates miR-486 expression in BM-MSCs. Lentivirus-mediated overexpression of miR-486 resulted in increase of hepatocyte growth factor (HGF) and vascular endothelial growth factor(VEGF) in both mRNA and protein levels. MiR-486 expression also promotes proliferation and reduces apoptosis of BM-MSCs. Whereas MiR-486 knockdown downregulated the secretion of HGF and VEGF and induced apoptosis of BM-MSCs. Furthermore, PTEN-PI3K/AKT signaling was validated to be involved in changes of BM-MSC biological functions regulated by miR-486. These results suggested that MiR-486 mediated the hypoxia-induced angiogenic activity and promoted the proliferation and survival of BM-MSCs through regulating PTEN-PI3K/AKT signaling. These findings might provide a novel understanding of effective therapeutic strategy for hypoxic-ischemic diseases.

Loss of Stromal IMP1 Promotes a Tumorigenic Microenvironment in the Colon.

The colon tumor microenvironment is becoming increasingly recognized as a complex but central player in the development of many cancers. Previously, we identified an oncogenic role for the mRNA-binding protein IMP1 (IGF2BP1) in the epithelium during colon tumorigenesis. In the current study, we reveal the contribution of stromal IMP1 in the context of colitis-associated colon tumorigenesis. Interestingly, stromal deletion of Imp1 (Dermo1Cre;Imp1(LoxP/LoxP), or Imp1(ΔMes)) in the azoxymethane/dextran sodium sulfate (AOM/DSS) model of colitis-associated cancer resulted in increased tumor numbers of larger size and more advanced histologic grade than controls. In addition, Imp1(ΔMes) mice exhibited a global increase in protumorigenic microenvironment factors, including enhanced inflammation and stromal components. Evaluation of purified mesenchyme from AOM/DSS-treated Imp1(ΔMes) mice demonstrated an increase in hepatocyte growth factor (HGF), which has not been associated with regulation via IMP1. Genetic knockdown of Imp1 in human primary fibroblasts confirmed an increase in HGF with Imp1 loss, demonstrating a specific, cell-autonomous role for Imp1 loss to increase HGF expression. Taken together, these data demonstrate a novel tumor-suppressive role for IMP1 in colon stromal cells and underscore an exquisite, context-specific function for mRNA-binding proteins, such as IMP1, in disease states. The tumor-suppressive role of stromal IMP1 and its ability to modulate protumorigenic factors suggest that IMP1 status is important for the initiation and growth of epithelial tumors.

Stromal Loss of mRNA‐Binding Protein IMP1 promotes a Pro‐Tumorigenic Colon Tumor Microenvironment in vivo

BackgroundInsulin‐like growth factor II mRNA‐binding protein 1 (IMP1) is an oncofetal protein that modulates mRNA stabilization, localization, and translation. Recent studies suggest that IMP1 may play a role in colonic mesenchymal stem cells during wound healing. We have demonstrated an oncogenic role for IMP1 in colorectal cancer (CRC) cells; however, it is not known how non‐epithelial IMP1 contributes to CRC in vivo.Methods: Using the azoxymethane/dextran sodium sulfate (AOM/DSS) model of colitis‐associated CRC, we evaluated tumorigenesis in mice with mesenchymal‐specific Imp1loss (Dermo1Cre;Imp1floxed mice;Imp1ΔMes). Furthermore, isolated mesenchyme from tumor‐bearing mice was evaluated for changes in growth factors and cytokines via antibody array.Results: We demonstrate that Imp1 ΔMesmice treated with AOM/DSS exhibit a significant increase in tumor number, size, and load compared to controls. Isolated mesenchmye from AOM/DSS‐ treated Imp1 ΔMes mice show, among other things, a significant increase in hepatocyte growth factor (HGF) expression, suggesting that IMP1 loss favors a pro‐tumorigenic environment, potentially via up‐regulation of the HGF pathway.ConclusionsOur results thus far indicate a novel, protective role for stromal IMP1 in colon tumorigenesis, likely via negative regulation of HGF signaling in the setting of colitis‐associated CRC. Future studies will determine the direct mechanisms for IMP1 regulation of the HGF pathway and may define a previously unknown, therapeutically tractable mechanism of stromal:epithelial crosstalk in CRC.Funding : NIH RO1 DK056645 (AKR), NIH K01 DK100485 (KEH) HHMI Medical Fellowship (ETL), NIH UO1 DK085551 (NIDDK/NIAID Intestinal Stem Cell Consortium)

Protective effect of aqueous extracts from Rhizopus oryzae on liver injury induced by carbon tetrachloride in rats.

Hepatoprotective effects of Rhizopus oryzae/ U-1 aqueous extract (RU) were demonstrated in carbon tetrachloride (CCl4 )-induced liver-injured rats. In order to investigate the RU effects, the rats were administered RU at a dose of 10 or 100 mg/kg of body weight for 10 days before induction of the liver injury by oral administration of CCl4 (125 mg/kg body weight). (i) Pretreatment with RU caused a significant decrease in serum lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities that were increased by the administration of CCl4 . (ii) RU pretreatment (100 mg/kg) increased 5-bromo-2'-deoxyuridine incorporation at 48 h after CCl4 treatment in hepatocytes. (iii) Histological hematoxylin and eosin staining of the liver showed that RU pretreatment reduced the damage induced by CCl4 administration. (iv) Reverse transcriptase PCR analysis showed RU retreatment caused a transient but significant increase in hepatocyte growth factor (HGF) and a sustained and significant increase in insulin-like growth factor-I (IGF-I) gene expression in hepatocytes injured by CCl4 treatment. From these results, we conclude that oral pre-administration of RU was effective to suppress liver injury induced by the subsequent oral CCl4 administration, and RU-induced increase in IGF-I and HGF gene expression may be, even in part, involved in biological actions of RU in rats.

Liver sinusoidal endothelial cells in disease – And for therapy?

Background & Aims: Capillarization, characterized by loss of differentiation of liver sinusoidal endothelial cells (LSECs), pre- cedes the onset of hepatic fibrosis. We investigated whether restora- tion of LSEC differentiation would normalize crosstalk with activated hepatic stellate cells (HSC) and thereby promote quiescence of HSC and regression of fibrosis. Methods: Rat LSECs were cultured with inhibitors and/or agonists and examined by scanning electron microscopy for fenestrae in sieve plates. Cirrhosis was induced in rats using thioacetamide, followed by administration of BAY 60-2770, an activator of soluble guanylate cyclase (sGC). Fibrosis was assessed by Sirius red staining; expression of a-smooth muscle actin was measured by immunoblot analysis. Results: Maintenance of LSEC differentiation requires vascular endothelial growth factor-A stimulation of nitric oxide-dependent signaling (via sGC and cyclic guanosine monophosphate) and nitric oxide-independent signaling. In rats with thioacetamide-induced cir- rhosis, BAY 60-2770 accelerated the complete reversal of capillariza- tion (restored differentiation of LSECs) without directly affecting activation of HSCs or fibrosis. Restoration of differentiation to LSECs led to quiescence of HSCs and regression of fibrosis in the absence of further exposure to BAY 60-2770. Activation of sGC with BAY 60- 2770 prevented progression of cirrhosis, despite continued adminis- tration of thioacetamide. Conclusions: The state of LSEC differentiation plays a pivotal role in HSC activation and the fibrotic process. Abstract: The ability of the liver to regenerate is crucial to protect liver function after injury and during chronic disease. Increases in hepatocyte growth factor (HGF) in liver sinusoidal endothelial cells (LSECs) are thought to drive liver regeneration. However, in contrast to endothelial progenitor cells, mature LSECs express little HGF. Therefore, we sought to establish in rats whether liver injury causes BM LSEC progenitor cells to engraft in the liver and provide increased levels of HGF and to examine the relative contribution of resident and BM LSEC progenitors. LSEC label-retaining cells and progenitors were identified in liver and LSEC progenitors in BM. BM LSEC progen- itors did not contribute to normal LSEC turnover in the liver. How- ever, after partial hepatectomy, BM LSEC progenitor proliferation and mobilization to the circulation doubled. In the liver, one-quarter of the LSECs were BM derived, and BM LSEC progenitors differenti- ated into fenestrated LSECs. When irradiated rats underwent partial hepatectomy, liver regeneration was compromised, but infusion of LSEC progenitors rescued the defect. Further analysis revealed that BM LSEC progenitors expressed substantially more HGF and were more proliferative than resident LSEC progenitors after partial hepatectomy. Resident LSEC progenitors within their niche may play a smaller role in recovery from partial hepatectomy than BM LSEC progenitors, but, when infused after injury, these progenitors engrafted and expanded markedly over a 2-month period. In conclusion, LSEC progenitor cells are present in liver and BM, and recruitment of BM LSEC progenitors is necessary for normal liver regeneration.

Liver sinusoidal endothelial cell progenitor cells promote liver regeneration in rats

The ability of the liver to regenerate is crucial to protect liver function after injury and during chronic disease. Increases in hepatocyte growth factor (HGF) in liver sinusoidal endothelial cells (LSECs) are thought to drive liver regeneration. However, in contrast to endothelial progenitor cells, mature LSECs express little HGF. Therefore, we sought to establish in rats whether liver injury causes BM LSEC progenitor cells to engraft in the liver and provide increased levels of HGF and to examine the relative contribution of resident and BM LSEC progenitors. LSEC label-retaining cells and progenitors were identified in liver and LSEC progenitors in BM. BM LSEC progenitors did not contribute to normal LSEC turnover in the liver. However, after partial hepatectomy, BM LSEC progenitor proliferation and mobilization to the circulation doubled. In the liver, one-quarter of the LSECs were BM derived, and BM LSEC progenitors differentiated into fenestrated LSECs. When irradiated rats underwent partial hepatectomy, liver regeneration was compromised, but infusion of LSEC progenitors rescued the defect. Further analysis revealed that BM LSEC progenitors expressed substantially more HGF and were more proliferative than resident LSEC progenitors after partial hepatectomy. Resident LSEC progenitors within their niche may play a smaller role in recovery from partial hepatectomy than BM LSEC progenitors, but, when infused after injury, these progenitors engrafted and expanded markedly over a 2-month period. In conclusion, LSEC progenitor cells are present in liver and BM, and recruitment of BM LSEC progenitors is necessary for normal liver regeneration.

Nitric oxide synthase inhibition delays low-frequency stimulation-induced satellite cell activation in rat fast-twitch muscle

This study examined the effect of nitric oxide synthase (NOS) inhibition via N(ω)-nitro-l-arginine methyl ester (l-NAME) administration on low-frequency stimulation-induced satellite cell (SC) activation in rat skeletal muscle. l-NAME only delayed stimulation-induced increases in SC activity. Also, stimulation-induced increases in hepatocyte growth factor (HGF) mRNA and protein expression were only abrogated at the mRNA level in l-NAME-treated animals. Therefore, early stimulation-induced SC activation appears to be NOS-dependent, while continued activation may involve NOS-independent HGF translational control mechanisms.

Molecular basis of anti‐inflammatory action of platelet‐rich plasma on human chondrocytes: Mechanisms of NF‐κB inhibition via HGF

Loss of articular cartilage through injury or disease presents major clinical challenges also because cartilage has very poor regenerative capacity, giving rise to the development of biological approaches. As autologous blood product, platelet-rich plasma (PRP) provides a promising alternative to surgery by promoting safe and natural healing. Here we tested the possibility that PRP might be effective as an anti-inflammatory agent, providing an attractive basis for regeneration of articular cartilage, and two principal observations were done. First, activated PRP in chondrocytes reduced the transactivating activity of NF-κB, critical regulator of the inflammatory process, and decreased the expression of COX-2 and CXCR4 target genes. By analyzing a panel of cytokines with different biological significance, in activated PRP we observed increases in hepatocyte growth factor (HGF), interleukin-4 and tumor necrosis factor-α (TNF-α). HGF and TNF-α, by disrupting NF-κB-transactivating activity, were important for the anti-inflammatory function of activated PRP. The key molecular mechanisms involved in PRP-inhibitory effects on NF-κB activity were for HGF the enhanced cellular IkBα expression, that contributed to NF-κB-p65 subunit retention in the cytosol and nucleo-cytoplasmic shuttling, and for TNF-α the p50/50 DNA-binding causing inhibition of target-gene expression. Second, activated PRP in U937-monocytic cells reduced chemotaxis by inhibiting chemokine transactivation and CXCR4-receptor expression, thus possibly controlling local inflammation in cartilage. In conclusion, activated PRP is a promising biological therapeutic agent, as a scaffold in micro-invasive articular cartilage regeneration, not only for its content of proliferative/differentiative growth factors, but also for the presence of anti-inflammatory agents including HGF.

Hepatocyte growth factor gene expression after massive small bowel resection: lack of stimulation in lung and liver.

Both hepatic and renal regeneration are associated with rapid increases in hepatocyte growth factor (HGF)mRNA levels, not only in the regenerating tissue, but also in the lung. In this study, changes in the levels of HGF mRNA in the terminal ileum and also in distal organs in the rat following massive small bowel resection (MSBR) have been investigated with a sensitive S1 nuclease assay. HGF mRNA levels are low in the ileum and increase only transiently post-MSBR. In contrast to the other models of regeneration, no increase in HGF mRNA levels is observed in the lung nor in kidney and liver post-MSBR. This suggests that the ileum does not release "injurin", the putative humoral mediator of the response of the lung observed after hepatectomy or nephrectomy.

Possible involvement of neutrophils in a serum level increase of hepatocyte growth factor in non-Hodgkin's lymphoma

Serum levels of hepatocyte growth factor (HGF), a potent angiogenic factor, increase during various haematological malignancies. In this study, we examined serum HGF in 59 patients with non-Hodgkin's lymphoma (NHL). Serum HGF levels in NHL patients were increased, as were levels in patients with multiple myeloma, chronic myeloproliferative disorders, and myelodysplastic syndrome. Some 29 patients with T-cell lymphoma, including 20 with adult T-cell leukemia/lymphoma, exhibited a significant increase in serum HGF, as did 23 with B-cell lymphoma. The levels of serum HGF correlated with increased neutrophil counts (r=0.487, p<0.0001), and also paralleled a neutrophil increase in NHL patients who received granulocyte-colony stimulating factor (G-CSF) at the nadir of neutrophil count following chemotherapy. Additionally, in in vitro experiments, HGF secretion from polymorphonuclear neutrophils and its expression in bone marrow myeloid cells were stimulated by G-CSF. Although HGF has been thought to be involved in the pathogenesis of NHL through its angiogenic activities, these results suggest that HGF production by neutrophils and myeloid lineage cells may also contribute to an increase in serum HGF in NHL patients.

Non-Paralleled Increase of Hepatocyte Growth Factor and Vascular Endothelial Growth Factor in the Eyes with Angiogenic and Nonangiogenic Fibroproliferation

Vascular endothelial growth factor (VEGF) has been known as principal angiogenic factor in vasculogenesis, tumor angiogenesis and ocular angiogenesis. Currently, hepatocyte growth factor (HGF) has been reported to play a major role in ocular angiogenesis. We studied distribution of both growth factors in angiogenic and non-angiogenic fibroproliferation to determine the correlation of VEGF and HGF in retinal angiogenesis. Concentrations of VEGF and HGF molecules in vitreous samples from 27 eyes with angiogenic proliferative diabetic retinopathy (PDR) and 9 eyes with non-angiogenic proliferative vitreoretinopathy (PVR) were measured by enzyme-linked immunosorbent assay (ELISA). Vitreous samples with idiopathic macular role (IMH) served as a control. Concentrations of VEGF in the angiogenic PDR were 4.3 ± 5.8 ng/ml (mean ± SD), and were significantly higher than in non-angiogenic PVR (0.5 ± 0.1 ng/ml). No significant differences were observed on VEGF concentrations between PVR to control. On the contrary, HGF concentrations were significantly higher in PVR (22.5 ± 21.8 ng/ml) than in control (6.9 ± 5.2 ng/ml), those of PDR (24.0 ± 16.3 ng/ml) were also significantly higher than control. Among PDR samples, VEGF concentration was significantly higher than in the subgroup with higher angiogenic activity represented by iris neovascularization, although there were no significant differences on HGF concentration between the subgroups. Focal increases in HGF on fibroproliferation in the eye regardless of the involvement of angiogenesis were not in remarkable relation with angiogenic activity, unlike VEGF. These data suggested a more extensive role of HGF than VEGF strictly related to angiogenesis.

Increase of hepatocyte growth factor after renal transplantation

Increase of hepatocyte growth factor after renal transplantation

Identification and characterization of "injurin," an inducer of expression of the gene for hepatocyte growth factor.

The marked and rapid increase of hepatocyte growth factor (HGF) mRNA in the intact lung of rats after partial hepatectomy or unilateral nephrectomy suggests the existence of a humoral factor mediating a signal of injury to distal organs and may induce the expression of HGF gene in these organs. We have now identified a proteinous factor in the sera of rats with injury of liver or kidney that increases HGF mRNA in the intact lung. When the serum of rats with liver insult caused by partial hepatectomy or ischemic treatment was injected i.p. into normal noninjured rats, it induced a marked HGF mRNA expression in the lung of the recipient rats. The addition of serum from rats with various hepatic or renal injuries to MRC-5 human embryonic lung fibroblasts in culture also led to the induction of HGF mRNA expression, so that the production of HGF by MRC-5 cells after treatment with the sera was remarkably increased in the culture medium. However, serum from the normal intact rat induced no HGF production and no HGF mRNA in the lung in vivo and lung fibroblasts in vitro. This factor, which increases HGF production, was purified greater than 200-fold from sera of CCl4-treated rats. The factor proved to be an acid- and heat-stable protein with an apparent molecular mass of 10-20 kDa in SDS/PAGE. Its activity markedly increased within 3-6 hr in the plasma of rats after various treatments that injured the liver or kidney. These results suggest that the factor specifically appears in the blood of rats with organ injury and may be involved in organ regeneration through the potential to increase the synthesis of HGF. Since the factor seems to mediate various organ injuries, we named it "injurin."

Hepatocyte growth factor (hepatopoietin A) rapidly increases in plasma before DNA synthesis and liver regeneration stimulated by partial hepatectomy and carbon tetrachloride administration

An enzyme-linked immunosorbent assay was used to measure the level of hepatocyte growth factor in rat plasma at various times after two-thirds partial hepatectomy or CCl4 administration. An initial 17-fold rise and 13-fold rise in the level of hepatocyte growth factor was observed 2 hr after partial hepatectomy and CCl4 treatment, respectively, well before the onset of DNA synthesis in the liver. The peaks of DNA synthesis in remnant livers and livers exposed to CCl4 occurred at 24 hr and 48 hr, respectively, as determined by 5-bromo-2′-deoxyuridine labeling and [3H]thymidine uptake by the liver. A later peak level (17-fold above control) of hepatocyte growth factor at 24 hr after CCl4 treatment coincided with strong immunostaining of damaged or necrotic hepatocytes around central veins with an antibody to hepatocyte growth factor. This suggests a later intrahepatic origin of the signals for liver regeneration after hepatotoxic injury subsequent to the early extrahepatic production of hepatocyte growth factor at 2 hr after CCl4 administration. The absence of staining in the liver remnants in partially hepatectomized rats implies that the increase in hepatocyte growth factor seen in the plasma is caused by production at extrahepatic site(s). Possible sources include the pancreas, brain, thyroid and salivary glands, and Brunner's glands of the duodenum. Norepinephrine also increases in plasma as early as 2 hr after hepatectomy. In vitro, [3H]thymidine incorporation into hepatocyte DNA in the presence of hepatocyte growth factor is greater if 10−5 mol/L norepinephrine is also present in the media. In contrast with other growth factors whose production by hepatocytes coincides with the peak of DNA synthesis (transforming growth factor α and acidic fibroblast growth factor), the hepatocyte growth factor increase in plasma occurs long before DNA synthesis and coincides with the observed increase in plasma norepinephrine at 2 to 4 hr after two-thirds partial hepatectomy. The concurrent elevation in plasma levels of the strongest hepatocyte mitogen (hepatocyte growth factor) and the strongest hepatocyte mitogenic amplifier (norepinephrine) probably serves to provide the mitogenic signal that initiates the first round of DNA synthesis during liver regeneration. (HEPATOLOGY 1991;13:743–749.)

Hepatocyte growth factor (hepatopoietin A) rapidly increases in plasma before DNA synthesis and liver regeneration stimulated by partial hepatectomy and carbon tetrachloride administration

An enzyme-linked immunosorbent assay was used to measure the level of hepatocyte growth factor in rat plasma at various times after two-thirds partial hepatectomy or CCl4 administration. An initial 17-fold rise and 13-fold rise in the level of hepatocyte growth factor was observed 2 hr after partial hepatectomy and CCl4 treatment, respectively, well before the onset of DNA synthesis in the liver. The peaks of DNA synthesis in remnant livers and livers exposed to CCl4 occurred at 24 hr and 48 hr, respectively, as determined by 5-bromo-2'-deoxyuridine labeling and [3H]thymidine uptake by the liver. A later peak level (17-fold above control) of hepatocyte growth factor at 24 hr after CCl4 treatment coincided with strong immunostaining of damaged or necrotic hepatocytes around central veins with an antibody to hepatocyte growth factor. This suggests a later intrahepatic origin of the signals for liver regeneration after hepatotoxic injury subsequent to the early extrahepatic production of hepatocyte growth factor at 2 hr after CCl4 administration. The absence of staining in the liver remnants in partially hepatectomized rats implies that the increase in hepatocyte growth factor seen in the plasma is caused by production at extrahepatic site(s). Possible sources include the pancreas, brain, thyroid and salivary glands, and Brunner's glands of the duodenum. Norepinephrine also increases in plasma as early as 2 hr after hepatectomy. In vitro, [3H]thymidine incorporation into hepatocyte DNA in the presence of hepatocyte growth factor is greater if 10(-5) mol/L norepinephrine is also present in the media.(ABSTRACT TRUNCATED AT 250 WORDS)