Hepatocyte Growth Factor Pretreatment Research Articles

The integrin-linked kinase-associated phosphatase (ILKAP) is a regulatory hub of ovarian cancer cell susceptibility to platinum drugs

BackgroundPlatinum drugs are the most powerful chemotherapeutic agents in the treatment of ovarian cancer. We demonstrated previously that unexpectedly ovarian cancer cells are sensitised to cisplatin (CDDP) by the hepatocyte growth factor (HGF), usually considered an anti-apoptotic factor. MethodsWe used quantitative polymerase chain reaction and Western blot analysis to evaluate gene and protein expression, immunofluorescence to evaluate protein localisation and functional assays to measure cell viability and apoptosis. ResultsIn ovarian cancer cells, CDDP induced the phosphorylation, i.e. the activation, of the p90RSK. Surprisingly, a 48-h-long cell pre-treatment with HGF reverted this activation. HGF pre-treatment also resulted in the increased expression of the integrin-linked kinase (ILK)-associated phosphatase (ILKAP) that dephosphorylated the p90RSK. Conversely, CDDP down-modulated ILKAP expression. This impaired CDDP efficacy, as ILKAP silencing protected cells from CDDP-induced death. In line, the biochemical inhibition of the p90RSK or the combined silencing of the most expressed RSK isoforms, namely RSK1 and RSK2, increased the efficacy of CDDP. However, p90RSK inhibition was not sufficient to revert cell protection from death after ILKAP suppression, because of the simultaneous increased activity of the anti-apoptotic kinases ILK and ILK substrate AKT, which were both dephosphorylated, i.e. negatively regulated, by ILKAP. Only the combined inhibition of p90RSK and ILK reverted the effect of ILKAP suppression. ConclusionsAs RSKs, ILK and AKT are vital kinases for ovarian cancer onset and progression, data suggest that ILKAP is a regulatory hub of ovarian cancer cell survival by controlling the activation of these kinases.

Abstract 1821: Hepatocyte growth factor sensitizes brain tumor cells and xenografts to c-Met kinase inhibition

Abstract The receptor tyrosine kinase c-Met and its ligand hepatocyte growth factor (HGF) are frequently deregulated in many cancers, including brain tumors. c-Met activation induces brain tumor malignancy and is associated with poor clinical outcome. Consequently, c-Met inhibitors have been developed by pharmaceutical companies. However, the factors that determine sensitivity to c-Met inhibitors have not been determined to date. In the present study, we systematically investigated the factor(s) that determine sensitivity of brain tumors to c-Met kinase inhibitors and thereby also uncovered a new strategy for enhancing sensitivity to the inhibitors. We investigated the effects of a clinically applicable c-Met kinase inhibitor, PF-2341066, on fifteen different medulloblastoma and glioma cells and stem cells that possess different molecular characteristics. We investigated potential correlations between the effects of PF-2341066 on cell proliferation and death and the levels of total c-Met, p-Met, HGF, PTEN and EGFR co-expression. PF-2341066 completely inhibited basal and HGF-induced c-Met activation in all cells. However, the effects of PF-2341066 on cell proliferation and cell death varied tremendously between the different cell lines. The anti-proliferative and anti-survival effects of PF-2341066 did not correlate with c-Met, phospho-Met or PTEN or EGFR expressions in the cells. However, there was a statistically significant correlation between HGF expression levels and PF-2341066-induced inhibition of cell proliferation and cell survival (p<0.01). Similarly, orthotopic xenografts derived from cell line with high HGF expression level were significantly stronger inhibited by oral administration of PF-2341066 to than xenografts derived from low-expressing HGF cells. Therefore, HGF co-expression is the best predictor of response to c-Met kinase inhibitors. Surprisingly, we also found that when glioma cells and stem cells are pretreated with HGF, PF-2341066 is able to induce significantly greater (34-79%) cell death than in non-pretreated cells (p<0.01). The optimal time of pre-activation that achieved strongest sensitization to c-Met inhibitor-induced cell death was 2-4 hours. In vivo experiments showed that short-term bolus HGF pre-treatment of glioma stem cell-derived xenografts significantly sensitized the tumors to c-Met inhibition by PF-2341066. We therefore hypothesize that short-term exogenous activation of c-Met by HGF is able to trigger fast oncogene addition and therefore sensitize brain tumors to c-Met inhibitors. Overall, our data identify for the first time HGF co-expression as the determining factor in tumor sensitivity to c-Met kinase inhibitors and uncover HGF pre-treatment as a new strategy for enhancing the effects of the inhibitors. These findings have important practical implications for the efficient use of recently developed c-Met kinase inhibitors in cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1821. doi:1538-7445.AM2012-1821

Hepatocyte growth factor preferentially activates the anti‐inflammatory arm of NF‐κB signaling to induce A20 and protect renal proximal tubular epithelial cells from inflammation

Inflammation induces the NF-κB dependent protein A20 in human renal proximal tubular epithelial cells (RPTEC), which secondarily contains inflammation by shutting down NF-κB activation. We surmised that inducing A20 without engaging the pro-inflammatory arm of NF-κB could improve outcomes in kidney disease. We showed that hepatocyte growth factor (HGF) increases A20 mRNA and protein levels in RPTEC without causing inflammation. Upregulation of A20 by HGF was NF-κB/RelA dependent as it was abolished by overexpressing IκBα or silencing p65/RelA. Unlike TNFα, HGF caused minimal IκBα and p65/RelA phosphorylation, with moderate IκBα degradation. Upstream, HGF led to robust and sustained AKT activation, which was required for p65 phosphorylation and A20 upregulation. While HGF treatment of RPTEC significantly increased A20 mRNA, it failed to induce NF-κB dependent, pro-inflammatory MCP-1, VCAM-1, and ICAM-1 mRNA. This indicates that HGF preferentially upregulates protective (A20) over pro-inflammatory NF-κB dependent genes. Upregulation of A20 supported the anti-inflammatory effects of HGF in RPTEC. HGF pretreatment significantly attenuated TNFα-mediated increase of ICAM-1, a finding partially reversed by silencing A20. In conclusion, this is the first demonstration that HGF activates an AKT-p65/RelA pathway to preferentially induce A20 but not inflammatory molecules. This could be highly desirable in acute and chronic renal injury where A20-based anti-inflammatory therapies are beneficial.

Hepatocyte growth factor protects human embryonic stem cell derived-neural progenitors from hydrogen peroxide-induced apoptosis

Promoting human embryonic stem cell (hESC)-derived-neural progenitor survival in the pro-apoptotic niche is pivotal for stem cell replacement therapy. The present study was designed to investigate the protective effect of hepatocyte growth factor (HGF) on hESC-derived neural progenitor injured by hydrogen peroxide (H 2O 2) exposure. Treatment of hESC-derived neural progenitor cells with HGF prior to H 2O 2 exposure conferred protective effect against oxidative stress-induced apoptosis. HGF treatment increased both phosphoinositide 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase1/2 (ERK1/2) phosphorylation. However, selective inhibition of each pathway supported that the activation of PI3K/AKT, but not ERK1/2, provides survival advantage to the neural progenitor cells. Further investigation indicated that HGF pretreatment could attenuate the decrease of the expression of Bcl-2 protein induced by H 2O 2, whereas the level of Bax was not affected. Additionally, we observed that H 2O 2-induced decrease of mitochondrial transmembrane potential, release of cytochrome c and increase of caspase-3 activation were alleviated by HGF pretreatment. These effects of HGF could be reversed by inhibition of the PI3K/Akt and ERKs pathways, indicating PI3K/Akt and ERKs signaling might be involved in HGF-mediated regulation of mitochondrial apoptotic pathway mediated by H 2O 2. The neuroprotective effect of HGF might potentially be useful in stem cell-based therapies for neurodegenerative disorders.

Abstract 215: CSE1L as a potential target to sensitize ovarian cancer cells to cisplatin

Abstract Human ovarian cancer is frequently (70% of cases) at advanced stage at presentation and requires multimodality treatment, consisting of cytoreductive surgery and chemotherapy based on platinum-drugs and taxanes. Patients are initially responsive to this treatment, but, in most cases, experience disease relapse because tumour cells acquire drug resistance. We demonstrated that the Hepatocyte Growth Factor (HGF) sensitizes to cisplatin (CDDP) and taxol an ovarian carcinoma cell line known to be resistant to platinum drugs: SK-OV-3, leading to an increased cancer cell death at very low drug doses both in vitro and in an animal model (Bardella et al., 2007; Rasola et al., 2004). This was an unexpected finding as HGF and its tyrosine kinase receptor, encoded by the MET oncogene, drives cell proliferation, survival and invasiveness during development and tumorigenesis. We also demonstrated that this effect is mediated by p38MAPK, which overwhelms the concomitant HGF activation of survival pathways, as the expression of a dominant negative form of p38MAPK abrogates the sensitization effect of HGF (Coltella et al., 2006). Using oligonucleotide microarrays, we studied the transcriptional responses of cell treated with CDDP in the presence or in the absence of HGF, and found that HGF pre-treatment modifies the transcriptional response to CDDP not only in SK-OV-3, but also in NIH-OVCAR-3, and TOV-21G ovarian cancer cells. The up- or down-modulation of the most differentially expressed genes found in common within these cell lines was reverted when the cells expressed a dominant negative form of p38MAPK, upholding once again the involvement of p38MAPK in this phenomenon. Among the top-ranked differentially expressed genes, which we identified, we focused functional studies on CSE1L/CAS. This gene is a nuclear transporter involved in both proliferation and apoptosis found to be amplified and over-expressed in ovarian cancer. Knocking down of CSE1L/CAS made ovarian cancer cells sensitized to low doses of cisplatin and triggered apoptosis while had no effect on other cancer and normal cell lines. In conclusion, we show that HGF and CDDP modulate transcription in ovarian cancer cells and that this transcriptional response is involved in apoptosis regulation. We also provide the proof-of-concept that the identified genes might be targeted to either increase the efficacy of chemotherapeutics or to revert chemotherapy resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 215.

Treatment response to bortezomib in multiple myeloma correlates with plasma hepatocyte growth factor concentration and bone marrow thrombospondin concentration

Multiple myeloma (MM) is associated with increased rate of bone marrow angiogenesis. Increased concentration of hepatocyte growth factor (HGF) is associated with poor prognosis in patients treated with conventional chemotherapy or thalidomide. We have shown previously that decreased level of thrombospondin, an angiogenesis inhibitor, correlates with poor response to high-dose chemotherapy. The aim of our current study was to evaluate association between therapeutic response to bortezomib and thrombospondin and HGF levels. Peripheral blood plasma concentration of HGF and bone marrow plasma concentration of thrombospondin were measured in patients with MM prior to the initiation of bortezomib therapy. Overall, 58 patients were enrolled, 44/58 (76%) of them with relapsed disease. Treatment outcomes were analyzed for possible associations with pretreatment HGF and thrombospondin levels. Patients who achieved complete response had significantly higher pretreatment HGF levels and lower pretreatment thrombospondin levels than others. More than 70% of patients with low pretreatment HGF and high pretreatment thrombospondin concentrations achieved very good partial response or complete response, in contrast to only 20% of patients with high HGF and low thrombospondin levels. High pretreatment thrombospondin and low pretreatment HGF concentrations are associated with therapeutic response to bortezomib in patients with MM.

HGF upregulates CXCR4 expression in gliomas via NF-κB: implications for glioma cell migration

Invasion is a hallmark of malignant gliomas and is the main reason for therapeutic failure and recurrence of the tumor. CXCR4 is a key chemokine receptor implicated in glioma cell migration whose expression is regulated by hypoxia. Here, we report that hepatocyte growth factor (HGF) upregulated CXCR4 protein expression in glioma cells. HGF pre-treatment increased migration of U87MG and LN229 glioma cells towards the CXCR4 ligand, stromal cell-derived factor-1alpha (SDF-1alpha). AMD3100, a CXCR4 inhibitor, inhibited the increased migration of HGF pre-treated LN229 glioma cells towards SDF-1alpha. Following exposure to HGF and hypoxia, both cell lines showed nuclear translocation of NF-kappaB (p65). The HGF- and hypoxia-induced nuclear translocation of NF-kappaB (p65) involved phosphorylation and degradation of IkappaB-alpha. Knock-down of NF-kappaB expression inhibited the induction of CXCR4 expression in response to HGF, but not to hypoxia. However, knock-down of NF-kappaB expression inhibited the induction of CXCR4 expression in response to hypoxia in the presence of HGF. NF-kappaB mediated migration towards SDF-1alpha in response to HGF. Knock-down of NF-kappaB expression resulted in decreased migration of HGF pre-treated glioma cells towards SDF-1alpha. Therefore, HGF upregulates CXCR4 expression via NF-kappaB and leads to enhanced migration. To our knowledge, this is the first report to show that a crosstalk mediated by NF-kappaB exists between the SDF-1alpha/CXCR4 and HGF/c-Met axes relevant to glioma cell migration. These findings imply that effective inhibition of glioma invasion should be directed against several ligand/receptor signaling pathways.

Magnitude-dependent effects of cyclic stretch on HGF- and VEGF-induced pulmonary endothelial remodeling and barrier regulation

Mechanical ventilation at high tidal volumes compromises the blood-gas barrier and increases lung vascular permeability, which may lead to ventilator-induced lung injury and pulmonary edema. Using pulmonary endothelial cell (ECs) exposed to physiologically [5% cyclic stretch (CS)] and pathologically (18% CS) relevant magnitudes of CS, we evaluated the potential protective effects of hepatocyte growth factor (HGF) on EC barrier dysfunction induced by CS and vascular endothelial growth factor (VEGF). In static culture, HGF enhanced EC barrier function in a Rac-dependent manner and attenuated VEGF-induced EC permeability and paracellular gap formation. The protective effects of HGF were associated with the suppression of Rho-dependent signaling triggered by VEGF. Five percent CS promoted HGF-induced enhancement of the cortical F-actin rim and activation of Rac-dependent signaling, suggesting synergistic barrier-protective effects of physiological CS and HGF. In contrast, 18% CS further enhanced VEGF-induced EC permeability, activation of Rho signaling, and formation of actin stress fibers and paracellular gaps. These effects were attenuated by HGF pretreatment. EC preconditioning at 5% CS before HGF and VEGF further promoted EC barrier maintenance. Our data suggest synergistic effects of HGF and physiological CS in the Rac-mediated mechanisms of EC barrier protection. In turn, HGF reduced the barrier-disruptive effects of VEGF and pathological CS via downregulation of the Rho pathway. These results support the importance of HGF-VEGF balance in control of acute lung injury/acute respiratory distress syndrome severity via small GTPase-dependent regulation of lung endothelial permeability.

Hepatocyte-specific c-Met Deletion Disrupts Redox Homeostasis and Sensitizes to Fas-mediated Apoptosis

The hepatocyte growth factor and its receptor c-Met direct a pleiotropic signal transduction pathway that controls cell survival. We previously demonstrated that mice lacking c-Met (Met-KO) in hepatocytes were hypersensitive to Fas-induced liver injury. In this study, we used primary hepatocytes isolated from Met-KO and control (Cre-Ctrl) mice to address more directly the protective effects of c-Met signaling. Loss of c-Met function increased sensitivity to Fas-mediated apoptosis. Hepatocyte growth factor suppressed apoptosis in Cre-Ctrl but not Met-KO hepatocytes concurrently with up-regulation of NF-kappaB and major antiapoptotic proteins Bcl-2 and Bcl-xL. Intriguingly, Met-KO hepatocytes exhibited intrinsic activation of NF-kappaBas well as Bcl-2 and Bcl-xL. Furthermore, unchallenged Met-KO cells displayed oxidative stress as evidenced by overproduction of reactive oxygen species, which was associated with greater NADPH and Rac1 activities, was blocked by the known NADPH oxidase inhibitors, and was paralleled by increased lipid peroxidation and reduced glutathione (GSH) content. N-Acetylcysteine, an antioxidant and GSH precursor, significantly reduced Jo2-induced cell death. Conversely, the GSH-depleting agent buthionine sulfoximine completely abolished the protective effects of N-acetylcysteine in Met-KO hepatocytes. In conclusion, genetic inactivation of c-Met in mouse hepatocytes caused defects in redox regulation, which may account for the increased sensitivity to Fas-induced apoptosis and adaptive up-regulation of NF-kappaB survival signaling. These data provide evidence that intact c-Met signaling is a critical factor in the protection against excessive generation of endogenous reactive oxygen species.

Cytokine-pretreatment of CD34 + cord blood stem cells in vitro reduces long-term cell engraftment in NOD/SCID mice

Stem cell homing, engraftment and organ regeneration are controlled by cytokines, chemokines and cell–cell interactions. In this paper, cytokine effects on homing- and engraftment-related characteristics of CD34 + cord blood cells were examined. Untreated CD34 + cells were mainly in the G 0/G 1 cell cycle phase, expressed adhesion receptors on a low level, were positive for vimentin, and negative for the epithelial marker cytokeratin 8/18. Treatment with stem cell factor (SCF) stimulated cell proliferation, increased the number of cells in S and G 2/M cell cycle phase as well as the expression of adhesion receptors. The expression of cytokeratin 8/18 was increased and that of vimentin remained unchanged. Hepatocyte growth factor (HGF) did not stimulate cell proliferation and expression of adhesion receptors, but increased expression of cytokeratin 8/18. In NOD/SCID mice, kinetics of stem cell distribution revealed a fast elimination of human cells from blood. An increase in the number of engrafted cells was observed in different mouse organs in a time-dependent manner, preferentially in bone marrow, spleen and liver. Pretreatment with SCF resulted in reduction of long-term engraftment in bone marrow. HGF pretreatment of cord blood cells showed no significant effects on long-term engraftment capacity in mouse organs compared to untreated cells. Our data provide in vivo evidence that pretreatment of CD34 + cells with SCF reduces long-term cell engraftment in NOD/SCID mice.

HGF protects cultured cortical neurons against hypoxia/reoxygenation induced cell injury via ERK1/2 and PI-3K/Akt pathways

Hepatocyte growth factor (HGF) has been revealed to exert multipotent activities on a variety of cells. In this study, we investigated whether HGF had a direct neuroprotection on cultured cerebral cortical neurons subjected to hypoxia/reoxygenation (H/R) and explored the intracellular signalings mediated the effects. The decrease in cell viability and increase in number of apoptotic cells resulting from H/R were significantly prevented by HGF pre-treatment. HGF stimulated both ERK1/2 and Akt activities in cortical neurons. Inhibition of ERK activation completely abolished the protective effects of HGF, and inhibition of Akt activation reduced, but did not completely eliminate the HGF mediated neuroprotection. It is suggested that the neuroprotection of HGF depend on ERK1/2 pathway, and, to a lesser extent, PI-3K/Akt pathway. In addition, we found that pre-treatment with HGF remarkably attenuated the decrease in expression of Bcl-2 and Bcl-xL induced by H/R, but failed to affect the amount of Bax. It is likely that Bcl-2 and Bcl-xL contribute to the protective effects of HGF.

Genes regulated by hepatocyte growth factor as targets to sensitize ovarian cancer cells to cisplatin

Advanced ovarian cancers are initially responsive to chemotherapy with platinum drugs but develop drug resistance in most cases. We showed recently that hepatocyte growth factor (HGF) enhances death of human ovarian cancer cell lines treated with cisplatin (CDDP) and that this effect is mediated by the p38 mitogen-activated protein kinase. In this work, we integrated genome-wide expression profiling, in silico data survey, and functional assays to identify transcripts regulated in SK-OV-3 ovarian cancer cells made more responsive to CDDP by HGF. Using oligonucleotide microarrays, we found that HGF pretreatment changes the transcriptional response to CDDP. Quantitative reverse transcription-PCR not only validated all the 15 most differentially expressed genes but also confirmed that they were primarily modulated by the combined treatment with HGF and CDDP and reversed by suppressing p38 mitogen-activated protein kinase activity. Among the differentially expressed genes, we focused functional analysis on two regulatory subunits of the protein phosphatase 2A, which were down-modulated by HGF plus CDDP. Decrease of each subunit by RNA interference made ovarian cancer cells more responsive to CDDP, mimicking the effect of HGF. In conclusion, we show that HGF and CDDP modulate transcription in ovarian cancer cells and that this transcriptional response is involved in apoptosis regulation. We also provide the proof-of-concept that the identified genes might be targeted to either increase the efficacy of chemotherapeutics or revert chemotherapy resistance.

Hepatocyte growth factor suppresses acute renal inflammation by inhibition of endothelial E-selectin

Vascular endothelial activation, marked by de novo expression of E-selectin, is an early and essential event in the process of leukocyte extravasation and inflammation. Evidence suggests that hepatocyte growth factor (HGF) ameliorates inflammation in animal models of renal disease, implying that HGF might inhibit specific components of the inflammatory response. This study examined the effect of HGF on endothelial E-selectin expression in acute inflammation induced by tumor necrosis factor (TNF)-α. In vitro, HGF suppressed TNF-α-induced cell surface expression of E-selectin in human umbilical vein endothelial cells (HUVEC) and inhibited E-selectin mediated monocytic adhesion to endothelial monolayers. HGF activated phosphatidylinositol 3-kinase (PI3K)–Akt that in turn inhibited its downstream transducer glycogen synthase kinase (GSK)3. Blockade of the PI3K–Akt pathway with specific inhibitors abrogated HGF induced inhibitory phosphorylation of GSK3 and suppression of E-selectin. In addition, selective inhibition of GSK3 activity by lithium suppressed TNF-α-induced E-selectin expression and monocytic adhesion, reminiscent of the action of HGF. Moreover, ectopic expression of an uninhibitable mutant GSK3β, in which the regulatory serine-9 is replaced by alanine, abolished HGF's suppressive effect on endothelial E-selectin. In vivo, administration of exogenous HGF reduced endothelial expression of E-selectin induced by bolus injection of TNF-α. This was associated with less sequestration of circulating fluorescence-labeled macrophages in the kidney. These findings suggest that HGF ameliorates acute renal inflammation in part by downregulating E-selectin mediated macrophage adhesion to the inflamed endothelium.

Ceramide-induced apoptosis: role of catalase and hepatocyte growth factor

The aim of this study was to elucidate cellular mechanisms involved in ceramide-induced apoptosis and its attenuation by hepatocyte growth factor (HGF). Human retinal pigmented epithelial cells (RPE) incubated with C 2 ceramide accumulated reactive oxygen species (ROS) in mitochondria and underwent apoptosis in a dose-dependent manner. Ceramide-treated cells showed increased caspase-3 activation and an increase in mitochondrial membrane permeability transition (MPT). Low doses of H 2O 2 (100 μM) alone induced negligible apoptosis; however, ceramide-induced apoptosis was significantly enhanced by co-incubation with H 2O 2 (100 μM). Furthermore, ceramide treatment significantly decreased catalase enzymatic activity and protein expression. HGF pretreatment (20 ng/ml) significantly inhibited ceramide-induced apoptosis and reduced the accumulation of ROS, the activation of caspase-3, and the increase in MPT and prevented the reduction in catalase activity and expression. Together, the data suggest that ceramide induces apoptosis in RPE cells by increasing ROS production, MPT, and caspase-3 activation. The ceramide effect is potentiated by H 2O 2 and associated with a reduction in catalase activity, suggesting that catalase plays a central role in regulating this apoptotic response. The ability of HGF to attenuate these effects demonstrates its effectiveness as an antioxidant growth factor.

Hepatocyte growth factor stimulates adenoviral-mediated gene transfer across the apical membrane of epithelial cells.

The apical surface of polarized epithelial cells is relatively resistant to gene delivery by various agents including adenoviral vectors. Hepatocyte growth factor (HGF) dedifferentiates previously well-polarized Madin-Darby canine kidney (MDCK) cell monolayers by altering cell-surface polarity and inhibiting tight junction function. We used an in vitro model of polarized MDCK cells grown on permeable supports to examine the effects of HGF pretreatment on adenoviral (Ad)-mediated gene delivery through the apical surface of epithelial cell monolayers. HGF pretreatment of MDCK cell monolayers for 72 h increased Ad-mediated gene transfer and expression of enhanced green fluorescent protein (EGFP) and luciferase in a dose-dependent fashion. Time-course analysis of HGF-induced stimulation of Ad-mediated gene transfer was seen after 24 h and increased further with pretreatment periods extending to 72 h. HGF pretreatment increased Ad-mediated gene transfer at varying multiplicity of infection (MOI; ranging from 0.2-2000). PCR analysis for adenoviral DNA in control and HGF-pretreated MDCK cells suggested increased entry of viral constructs into HGF-pretreated MDCK cell monolayers. HGF-induced alterations in cell polarity are reversible upon removal of HGF. These data demonstrate that HGF pretreatment of MDCK cells increases the sensitivity of the cells to Ad-mediated gene delivery. The mechanism by which this occurs appears to be through increased entry of adenovirus into epithelial cells. These data provide evidence that biological agents that transiently alter epithelial cell polarity and tight junction function can be used to augment Ad-mediated gene delivery into epithelial cells from the apical surface.

A possible mechanism for prevention of intestinal programmed cell death after ischemia-reperfusion injury by hepatocyte growth factor pretreatment

Background/Purpose: Intestinal ischemia-reperfusion (IR) injury produces necrosis and apoptosis resulting in tissue loss. The authors have observed previously that pretreatment with hepatocyte growth factor (HGF) attenuates enterocyte apoptosis after IR. This study investigated the effects of HGF on tissue levels of caspase-8, an apoptosis initiator, and caspase-3, an apoptosis effector, in intestinal mucosa after IR. Methods: Thirty rats underwent placement of jugular venous catheters connected to osmotic pumps; 15 rats received vehicle, and 15 rats received HGF (150 μg/kg/d). After a 48-hour infusion, 5 rats from each group underwent either 35 minutes of superior mesenteric artery occlusion alone, or ischemia followed by 2 or 6 hours of reperfusion. Mucosal protein was analyzed for caspase-8 and caspase-3 activity. DNA fragmentation was used to measure the presence of apoptosis. Statistical significance was determined using analysis of variance. Results: After 6 hours of reperfusion, caspase-3 activity was increased significantly in control animals (P <.05). In HGF-pretreated animals, caspase-8 and caspase-3 activities were significantly reduced at 6 hours compared with control animals (P <.05). Conclusion: By preventing the activation of enterocyte caspase enzymes, and, thus, reducing apoptosis, HGF may enhance preservation of the intestine after IR injury. J Pediatr Surg 37:1696-1699. Copyright 2002, Elsevier Science (USA). All rights reserved.

Hepatoctye growth factor pretreatment reduces apoptosis and mucosal damage after intestinal ischemia-reperfusion

Background/Purpose: Ischemia-reperfusion (IR) injury to the intestine can result in mucosal damage and cellular death. This study was designed to evaluate the protective effects of pretreatment with hepatocyte growth factor (HGF) on intestine after moderate IR injury. Methods: Control animals (n = 7) received 48 hours of intravenous saline, and treatment animals (n = 7) received HGF (150 μg/kg/d). After 35 minutes of mesenteric artery occlusion and 120 minutes of reperfusion, serum and jejunal mucosa samples were obtained. Fluorometric assays were performed for hexosaminidase A (HEX A) and β-glucuronidase (GLUC), enzyme markers of enterocyte necrosis. Apoptosis was quantified by the TUNEL method. Transcription of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) was assessed by multiplex reverse transcription polymerase chain reaction (RT-PCR) Statistical analysis was performed using the Student's t test. Results: After HGF pretreatment, HEX A and GLUC activities were reduced from 543 ± 28 to 343 ± 35 nmole/h/mL (P <.01) and 183 ± 29 to 119 ± 22 nmole/h/mL (P <.01), respectively. Pretreated animals had a reduced number of apoptotic cells per 10 crypts (33 ± 11) compared with untreated rats (225 ± 24) after IR injury (P <.01). Mean IFN-γ band intensity was lower in HGF-pretreated animals (0.05 ± 0.02) compared with controls (0.31 ± 0.09; P <.05). Conclusions: Pretreatment with HGF reduces the severe crypt apoptosis and cellular necrosis after IR injury to the intestine. These data suggest that HGF may be beneficial in attenuating IR damage and thus may have significant clinical application. J Pediatr Surg 37:1093-1097. Copyright 2002, Elsevier Science (USA). All rights reserved.

Susceptibility of epithelial cells to Pseudomonas aeruginosa invasion and cytotoxicity is upregulated by hepatocyte growth factor.

Normal cell polarity protects epithelial cells against Pseudomonas aeruginosa invasion and cytotoxicity. Using epithelial cell clones with selective defects in sorting of membrane constituents, and using hepatocyte growth factor pretreatment, we found that polarized susceptibility to P. aeruginosa can be altered without disrupting tight junctions. The results also showed that cellular susceptibility factors for invasion and cytotoxicity are not the same, although both are localized to the basolateral cell surface in polarized epithelial cells.

Hepatocyte growth factor and its actions in growth plate chondrocytes.

Hepatocyte growth factor (HGF) has been implicated as a paracrine regulator of organogenesis and repair in many tissues. Here we have studied the expression and actions of HGF in intact rachitic rat growth plate and derived cultures of proliferative zone chondrocytes. In vivo and in vitro chondrocytes express HGF mRNA; 1,25(OH)2 has a three-fold maximal stimulatory effect, which can be blocked by H-7, an inhibitor of protein kinase C. Although HGF elaboration and action generally follow a paracrine model, chondrocytes appear capable of both expressing and responding to HGF. mRNA encoding the HGF receptor (c-met) was detected in both growth cartilage and derived chondrocyte cultures. HGF addition to chondrocyte cultures increased collagen II mRNA and alkaline phosphatase enzymatic activity to degrees comparable to that observed for active vitamin D metabolites. Combining HGF and 1,25-D evoked a synergistic response (ninefold) of alkaline phosphatase activity. To assess whether a similar stimulatory effect might be seen with bioactive peptides and HGF, we investigated the effect of HGF pretreatment on acute responses of chondrocytes to synthetic human calcitonin, an anabolic chondrocyte regulator whose skeletal action are mediated principally by cAMP elevation and subsequent protein kinase A activation. CT's maximal activation of protein kinase A was increased by prior HGF treatment from 56% to 78%. In concert, our findings indicate that in addition to HGF's classical paracrine role during skeletal growth, this growth factor may modulate hormonal sensitivity of the chondrocyte during proliferation, differentiation, and/or apoptosis.