Effect of scatter factor and hepatocyte growth factor on motility and morphology of MDCK cells

Bioactive Compounds for the Treatment of Renal Disease

Kidney diseases including acute kidney injury and chronic kidney disease are among the largest health issues worldwide. Dialysis and kidney transplantation can replace a significant portion of renal function, however these treatments still have limitations. To overcome these shortcomings, a variety of innovative efforts have been introduced, including cell-based therapies. During the past decades, advances have been made in the stem cell and developmental biology, and tissue engineering. As part of such efforts, studies on renal cell therapy and artificial kidney developments have been conducted, and multiple therapeutic interventions have shown promise in the pre-clinical and clinical settings. More recently, therapeutic cell-secreting secretomes have emerged as a potential alternative to cell-based approaches. This approach involves the use of renotropic factors, such as growth factors and cytokines, that are produced by cells and these factors have shown effectiveness in facilitating kidney function recovery. This review focuses on the renotropic functions of bioactive compounds that provide protective and regenerative effects for kidney tissue repair, based on the available data in the literature.

A cellular automaton based on plasma membrane turnover accurately recapitulates cell mechanics during epithelial scattering

Epithelial cells can be triggered to actively detach from epithelial tissues and become solitary, migratory and invasive. This process occurs repeatedly in development, where it is termed epithelial-mesenchymal transition (EMT), and can be recapitulated as epithelial scattering in cell culture models. Detachment of cell-cell junctions involves changes in contractile forces, actin cytoskeletal organization, changes in cell-substrate adhesion properties, surface presentation of cell-cell adhesion molecules, and gene expression. That these cellular processes affect each other and share molecular components creates difficulties in generating hypotheses and designing experiments to understand the mechanics of epithelial scattering. Computational modeling is proving a powerful too in such instances. Here we develop a cellular automaton to reveal insights into how cells rupture epithelial cell-cell junctions during scattering. The model is optimized for realistic and stable recapitulation of behavior of single cells, then for realistic simulation of multiple cells forming epithelial colonies. With a workable model of epithelial cell behavior, we then alter model parameters and assess whether we can realistically mimic epithelial scattering. Adjusting model parameters to recapitulate epithelial scattering reveals that induction of cell migration is the major driver of epithelial scattering.

Control of cell mechanics by RhoA and calcium fluxes during epithelial scattering

Epithelial tissues use adherens junctions to maintain tight interactions and coordinate cellular activities. Adherens junctions are remodeled during epithelial morphogenesis, including instances of epithelial-mesenchymal transition, or EMT, wherein individual cells detach from the tissue and migrate as individual cells. EMT has been recapitulated by growth factor induction of epithelial scattering in cell culture. In culture systems, cells undergo a highly reproducible series of cell morphology changes, most notably cell spreading followed by cellular compaction and cell migration. These morphology changes are accompanied by striking actin rearrangements. The current evidence suggests that global changes in actomyosin-based cellular contractility, first a loss of contractility during spreading and its activation during cell compaction, are the main drivers of epithelial scattering. In this review, we focus on how spreading and contractility might be controlled during epithelial scattering. While we propose a central role for RhoA, which is well known to control cellular contractility in multiple systems and whose role in epithelial scattering is well accepted, we suggest potential roles for additional cellular systems whose role in epithelial cell biology has been less well documented. In particular, we propose critical roles for vesicle recycling, calcium channels, and calcium-dependent kinases.

Epithelial-mesenchymal transition: a cancer researcher's conceptual friend and foe

Epithelial-mesenchymal transition (EMT) describes a series of rapid changes in cellular phenotype. During EMT, epithelial cells down-modulate cell-cell adhesion structures, alter their polarity, reorganize their cytoskeleton, and become isolated, motile, and resistant to anoikis. The term EMT is often applied to distinct biological events as if it were a single conserved process, but in fact EMT-related processes can vary in intensity from a transient loss of cell polarity to the total cellular reprogramming, as found by transcriptional analysis. Based on clinical observations, it is more appropriate in most cases to describe the emergence of an EMT-like phenotype during tumor progression. Although EMT implies complete trans-differentiation, EMT-like emphasizes the intermediary phenotype associated with tumor cell renewal and adaptation to specific microenvironments. Here, we categorize the various EMT-like phenotypes found in human carcinomas that, depending on the tumor type, may or not represent analogous stages in tumor progression. We based these categories on the global tumor phenotype. The tumor microenvironment, which is associated with stromal reactions, hypoxia, paucity of nutrients, impaired differentiation, and activation of various EMT-associated pathways, modulates overall tumor phenotype and leads to tumor heterogeneity.

Epithelial-mesenchymal transition: a cancer researcher's conceptual friend and foe

Epithelial-mesenchymal transition (EMT) describes a series of rapid changes in cellular phenotype. During EMT, epithelial cells down-modulate cell-cell adhesion structures, alter their polarity, reorganize their cytoskeleton, and become isolated, motile, and resistant to anoikis. The term EMT is often applied to distinct biological events as if it were a single conserved process, but in fact EMT-related processes can vary in intensity from a transient loss of cell polarity to the total cellular reprogramming, as found by transcriptional analysis. Based on clinical observations, it is more appropriate in most cases to describe the emergence of an EMT-like phenotype during tumor progression. Although EMT implies complete trans-differentiation, EMT-like emphasizes the intermediary phenotype associated with tumor cell renewal and adaptation to specific microenvironments. Here, we categorize the various EMT-like phenotypes found in human carcinomas that, depending on the tumor type, may or not represent analogous stages in tumor progression. We based these categories on the global tumor phenotype. The tumor microenvironment, which is associated with stromal reactions, hypoxia, paucity of nutrients, impaired differentiation, and activation of various EMT-associated pathways, modulates overall tumor phenotype and leads to tumor heterogeneity.

Keratinocyte and hepatocyte growth factors in the lung: roles in lung development, inflammation, and repair

A growing body of evidence indicates that the epithelial-specific growth factors keratinocyte growth factor (KGF), fibroblast growth factor (FGF)-10, and hepatocyte growth factor (HGF) play important roles in lung development, lung inflammation, and repair. The therapeutic potential of these growth factors in lung disease has yet to be fully explored. KGF has been best studied and has impressive protective effects against a wide variety of injurious stimuli when given as a pretreatment in animal models. Whether this protective effect could translate to a treatment effect in humans with acute lung injury needs to be investigated. FGF-10 and HGF may also have therapeutic potential, but more extensive studies in animal models are needed. Because HGF lacks true epithelial specificity, it may have less potential than KGF and FGF-10 as a targeted therapy to facilitate lung epithelial repair. Regardless of their therapeutic potential, studies of the unique roles played by these growth factors in the pathogenesis and the resolution of acute lung injury and other lung diseases will continue to enhance our understanding of the complex pathophysiology of inflammation and repair in the lung.

Hepatocyte growth factor in renal failure: promise and reality

Can science discover some secrets of Greek mythology? In the case of Prometheus, we can now suppose that his amazing hepatic regeneration was caused by a peptide growth factor called hepatocyte growth factor (HGF). Increasing evidence indicates that HGF acts as a multifunctional cytokine on different cell types. This review addresses the molecular mechanisms that are responsible for the pleiotropic effects of HGF. HGF binds with high affinity to its specific tyrosine kinase receptor c-met, thereby stimulating not only cell proliferation and differentiation, but also cell migration and tumorigenesis. The three fundamental principles of medicine-prevention, diagnosis, and therapy-may be benefited by the rational use of HGF. In renal tubular cells, HGF induces mitogenic and morphogenetic responses. In animal models of toxic or ischemic acute renal failure, HGF acts in a renotropic and nephroprotective manner. HGF expression is rapidly up-regulated in the remnant kidney of nephrectomized rats, inducing compensatory growth. In a mouse model of chronic renal disease, HGF inhibits the progression of tubulointerstitial fibrosis and kidney dysfunction. Increased HGF mRNA transcripts were detected in mesenchymal and tubular epithelial cells of rejecting kidney. In transplanted patients, elevated HGF levels may indicate renal rejection. When HGF is considered as a therapeutic agent in human medicine, for example, to stimulate kidney regeneration after acute injury, strategies need to be developed to stimulate cell regeneration and differentiation without an induction of tumorigenesis.

Hepatocyte growth factor/scatter factor-induced intracellular signalling

Hepatocyte growth factor (HGF) identical to scatter factor (SF) is a glycoprotein involved in the development of a number of cellular phenotypes, including proliferation, mitogenesis, formation of branching tubules and, in the case of tumour cells, invasion and metastasis. This fascinating cytokine transduces its activities via its receptor encoded by the c-met oncogene, coupled to a number of transducers integrating the HGF/SF signal to the cytosol and the nucleus. The downstream transducers coupled to HGF/MET, most of which participate in overlapping pathways, determine the development of the cell's phenotype, which in most cell types is dual.

Detection and characterization of an activity which aligns mesodermal cells into parallel arrays

A cell line of mesodermal origin, FS9, was found to release a Cell Orienting Factor into its culture medium. In contrast with the random migration of controls, the orienting activity causes migrating mesenchymal cells to form an orderly "halo' surrounding tissue explants; individual cells and their cytoskeletons are elongated and parallel to each other but at right angle to the explant. No effect on the rate of cell movement was apparent. The orienting activity could be quantified by counting the number of cells found within strings radiating at right angles to a single tissue explant in the presence of FS9 conditioned medium or by using NIH image analysis. A dose dependent relationship with half maximal activity occurring at a 25% dilution of conditioned medium was observed. Cells that migrated randomly in the absence of conditioned medium became oriented within 4 h of exposure to 50% conditioned medium. Conversely, when the conditioned medium was removed, parallel alignment was rapidly lost. The orienting activity was found in conditioned media from a variety of mesodermal derivatives. Transformation of Balb/c 3T3 cells using EJ-ras oncogene led to augmented production of the activity. Furthermore, insulin was required in serum-free medium to support its production, Laminin, fibronectin and collagen and a range of pure cytokines, neither promoted nor inhibited orientation. Cell alignment was also unaffected by treatments which interfered with cell-substrate interactions and motility including the addition of the RGD peptide or anti-integrin beta 1 and beta 3 antibodies. A protein is likely to be involved since the activity was heat and trypsin sensitive and non-dialysable. The possibility is discussed that the orienting activity is a novel protein(s) which alters intercellular interactions to promote the formation of an aligned pattern by migrating mesenchymal cells.

Cryopreservation of rat hepatocyte monolayer cultures

1. Most previous attempts to cryopreserve hepatocytes have used suspensions stored at either -70 degrees C or in liquid nitrogen, and the major problem is that these do not, on subsequent thawing, attach well in culture. This limits their use in studies of drug metabolism and xenobiotic-induced toxicity. In this manuscript we demonstrate successful cryopreservation of rat hepatocytes as monolayers attached to a collagen film. 2. Monolayers can be frozen and thawed without significant loss of cells, and although damage to the internal and plasma membranes is evident immediately post-thaw, a remarkable repair process takes place over 24-48 h post-thaw. Immediately post-thaw only 10% of the cells exclude Trypan Blue, but by 48 h 80-90% of the thawed cells are viable, indicating that repair of the plasma membranes has taken place. 3. The cells post-thaw retain aspects of liver-specific function including cytochrome P450 content and albumin synthesis. However, cytosolic proteins are lost through the damaged membranes and, probably because of this, urea synthesis from ammonia is retained at only 25% of pre-freeze values. 4. A cryopreservation method based on adherent hepatocytes on a collagen substrate overcomes the problems encountered with culture of cryopreserved hepatocyte suspensions, and may provide a practical means of establishing a 'bank' of hepatocytes from several donors and species.

Hepatocyte growth factor is involved in formation of osteoclast-like cells mediated by clonal stromal cells (MC3T3-G2/PA6)

Osteoclast formation from hemopoietic precursors has been shown to require the support of stromal cells in bone tissue. In this study, we demonstrated that hepatocyte growth factor (HGF) is one of the stromal cell-derived molecules responsible for osteoclast-like cell formation. For our experiments, we used a coculture system for osteoclastic cell formation and activation in which hemopoietic blast cells are cocultured with calvaria-derived stromal MC3T3-G2/PA6 (PA6) cells on dentine slices in the presence of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Addition of anti-HGF neutralizing IgG to the cocultures inhibited the formation of osteoclastic cells and their dentine-resorbing activity. We detected a single 6.0-kb transcript for HGF in PA6 cells, and also recognized immunoreactive M(r) 81,000 and 88,000 forms of HGF in conditioned medium (CM) from PA6 cell cultures, the level of which reached 6 ng/ml. Both the CM and HGF stimulated the proliferation of blast cells synergistically with granulocyte-macrophage colony-stimulating factor, resulting in an increased number of osteoclast precursors that respond to 1,25(OH)2D3 that are tartrate-resistant acid phosphatase-positive multinucleate cells in stromal cell-free blast cell cultures in plastic wells. The effect of the CM was diminished by the addition of anti-HGF IgG. However, neither the CM nor HGF stimulated the formation of osteoclastic cells and pits on dentine slices in the absence of PA6 cells. These results suggest that although HGF cannot completely replace stromal cells, it is one of the paracrine mediators produced by stromal cells that act on proliferation of osteoclastic cell precursors.

Comparative effects of hepatocyte growth factor and epidermal growth factor on motility, morphology, mitogenesis, and signal transduction of primary rat hepatocytes

Hepatocyte growth factor (HGF) and epidermal growth factor (EGF) are major hepatocyte mitogens, but HGF, also known as scatter factor (SF), has also been shown as a potent motogen for epithelial and endothelial cells. The mechanisms by which HGF is a stronger motogen compared to other mitogens are not understood. Here we report a comparative study of the effect of the two growth factors on cultured primary rat hepatocytes regarding their differential effects on morphology, mitogenicity, and motility as well as the phosphorylation of cytoskeletal-associated proteins. Using three different motility assays, both HGF and EGF increased the motility of hepatocytes, but HGF consistently elicited a significantly greater motility response than EGF. Additionally, HGF induced a more flattened, highly spread morphology compared to EGF. To examine if HGF and EGF phosphorylated different cytoskeletal elements as signal transduction targets in view of the observed variation in morphology and motility, primary cultures of 32P-loaded rat hepatocytes were stimulated by either HGF or EGF for up to 60 min. Both mitogens rapidly stimulated four isoforms of MAP kinase with similar kinetics and also rapidly facilitated the phosphorylation of cytoskeletal-associated F-actin. Two cytoskeletal-associated proteins, however, were observed to undergo rapid phosphorylation by HGF and not EGF during the time points described. One protein of 28 kDa was observed to become phosphorylated fivefold over controls, while the EGF-stimulated cells showed only a slight increase in the phosphorylation of this protein. Another protein with an apparent mwt of 42 kDa was phosphorylated 20-fold at 1 min and remained phosphorylated over 50-fold over control up to the 60 min time point. This protein was observed to become phosphorylated by EGF only after 10 min, and to a lesser extent (20-fold). Taken together, the data suggest that HGF and EGF stimulate divergent as well as redundant signal transduction pathways in the hepatocyte cytoskeleton, and this may result in unique HGF- or EGF-specific motility, morphology, and mitogenicity in hepatocytes.

Expression of scatter factor/hepatocyte growth factor is regionally correlated with the initiation of sperm motility in murine male genital tract: is scatter factor/hepatocyte growth factor involved in initiation of sperm motility?

Based upon findings that the scatter factor/hepatocyte growth factor (SF/HGF) has strong mitogenic and motogenic properties, and that the sperm cell acquires its fertilizing capacity and motility in the distal parts of mammalian epididymis, the present study was conducted to investigate the role of SF/HGF in initiation of sperm cell motility. This was investigated by determining the expression of SF/HGF in various regions of the murine male genital tract by scatter and cell tracking assays using MDCK epithelial cells, Western blot procedure, and the immunohistochemical procedure using paraffin sections of various regions of the male genital tract. The findings from all these assays indicate that SF/HGF is differentially expressed in various parts of the male genital tract with slight or no expression in the testes, caput epididymis, and vas deferens, and with the highest expression in cauda and corpus (distal) epididymis followed by expression in the corpus (proximal) epididymis. This region-specific SF/HGF expression pattern coincides with the pattern of acquiring the fertilizing capacity and motility by the sperm cell during its transit through the male genital tract. However, wherever SF/HGF was expressed in the male genital tract, its molecular weight was slightly higher (Mr, 82 kD), compared to the SF/HGF expressed in various other somatic tissues (Mr, 78 kD), indicating that the genital tract SF/HGF may be a different molecular species that shares some immunoreactive epitopes with the somatic cell SF/HGF. Incubation of immotile sperm from caput epididymis with the purified human placental SF/HGF of 78 kD initiated motility in 5-15% of sperm population. These results strongly suggest that the SF/HGF-like activity is expressed in the male genital tract in a region-specific manner, and this activity may have a role in initiation of sperm motility acquired during its transit through the epididymis in mammals.

Disruption of epithelial cell-matrix interactions induces apoptosis

Cell-matrix interactions have major effects upon phenotypic features such as gene regulation, cytoskeletal structure, differentiation, and aspects of cell growth control. Programmed cell death (apoptosis) is crucial for maintaining appropriate cell number and tissue organization. It was therefore of interest to determine whether cell-matrix interactions affect apoptosis. The present report demonstrates that apoptosis was induced by disruption of the interactions between normal epithelial cells and extracellular matrix. We have termed this phenomenon "anoikis." Overexpression of bcl-2 protected cells against anoikis. Cellular sensitivity to anoikis was apparently regulated: (a) anoikis did not occur in normal fibroblasts; (b) it was abrogated in epithelial cells by transformation with v-Ha-ras, v-src, or treatment with phorbol ester; (c) sensitivity to anoikis was conferred upon HT1080 cells or v-Ha-ras-transformed MDCK cells by reverse-transformation with adenovirus E1a; (d) anoikis in MDCK cells was alleviated by the motility factor, scatter factor. The results suggest that the circumvention of anoikis accompanies the acquisition of anchorage independence or cell motility.

Effect of hepatocyte growth factor/scatter factor and other growth factors on motility and morphology of non-tumorigenic and tumor cells

Using an automated cell analyzer system, the effect of hepatocyte growth factor/scatter factor (HGF/SF), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), endothelial acidic fibroblast growth factor (a-FGF), platelet derived growth factor (PDGF), and recombinant human insulinlike growth factor (IGF) on the motility and morphology of Madin-Darby canine kidney (MDCK), rat hepatomas, C2, and H5-6 and murine mammary carcinoma (EMT-6) cells was investigated. Treatment of MDCK cells with HGF/SF, bFGF, EGF, and a-FGF resulted in an increase in average cell velocity and in the fraction of moving cells. Cells treated with the PDGF and IGF did not show significant alterations in velocity. MDCK cells treated with each growth factor were classified into groups of "fast" and "slow" moving cells based on their average velocities, and the average morphologic features of the two groups were quantitated. Fast-moving cells had larger average area, circularity, and flatness as compared to slow-moving cells. Factors that stimulated cell movement also induced alterations in cell morphologic parameters including spreading, flatness, area, and circularity. HGF/SF also scattered and stimulated motility of C2 and H5-6 hepatoma cells. In contrast to MDCK cells, there was no significant difference between the morphology of the fast moving and slow moving C2 and H5-6 cells. These studies suggest that growth factor cytokines have specific effects on motility of normal and tumor cells.