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Endothelin-1 induces an angiogenic phenotype in cultured endothelial cells and stimulates neovascularization in vivo.

The endothelial cell-derived endothelin-1 (ET-1) is a potent mitogen for endothelial cells, vascular smooth muscle cells, and tumor cells. In this study, we analyzed the role of ET-1 on human umbilical vein endothelial cell (HUVEC) phenotype related to different stages of angiogenesis. ET-1 promoted HUVEC proliferation, migration, and invasion in a dose-dependent manner. The ET(B) receptor (ET(B)R) antagonist, BQ 788, blocked the angiogenic effects induced by ET-1, whereas the ET(A)R antagonist was less effective. ET-1 stimulated matrix metalloproteinase-2 mRNA expression and metalloproteinase-2 production, as determined by reverse transcriptase-polymerase chain reaction and gelatin zymography. Furthermore ET-1 was able to enhance HUVEC differentiation into cord vascular-like structures on Matrigel. When tested in combination with vascular endothelial growth factor (VEGF), ET-1 enhanced VEGF-induced angiogenic-related effects on endothelial cells in vitro. Finally, using the Matrigel plug neovascularization assay in vivo, ET-1 in combination with VEGF stimulated an angiogenic response comparable to that elicited by basic fibroblast growth factor. These findings demonstrated that ET-1 induces angiogenic responses in cultured endothelial cells through ET(B)R and that stimulates neovascularization in vivo in concert with VEGF. ET-1 and its receptors acting as angiogenic regulators might represent new targets for anti-angiogenic therapy.

Cell Differentiation↗

Shedding of the matrix metalloproteinases MMP-2, MMP-9, and MT1-MMP as membrane vesicle-associated components by endothelial cells.

Production of matrix-degrading proteases, particularly matrix metalloproteinases (MMPs), by endothelial cells is a critical event during angiogenesis, the process of vessel neoformation that occurs in normal and pathological conditions. MMPs are known to be highly regulated at the level of synthesis and activation, however, little is known about the regulation of MMP secretion by endothelial cells. We found that cultured human umbilical vein endothelial cells shed vesicles (300 to 600 nm) originating from localized areas of the cell plasma membrane, as revealed by ultrastructural analysis. Normal and reverse zymography, Western blot, and immunogold analyses of the vesicles showed two gelatinases, MMP-2 and MMP-9, in both the active and proenzyme forms, the MT1-MMP proenzyme located on the external side of the vesicle membrane and the two inhibitors TIMP-1 and TIMP-2. Serum and the angiogenic factors, fibroblast growth factor-2 and vascular endothelial growth factor, stimulated the shedding of MMPs as vesicle components. Shedding the vesicle was rapid, as it was already completed after 4 hours. Addition of shed vesicles to human umbilical vein endothelial cells resulted in autocrine stimulation of invasion through a layer of reconstituted basement membrane (Matrigel) and cord formation on Matrigel. We conclude that endothelial cells shed MMP-containing vesicles and this may be a mechanism for regulating focalized proteolytic activity vital to invasive and morphogenic events during angiogenesis.

Cells, Cultured↗

Inhibition of angiogenesis and vascular tumor growth by interferon-producing cells: A gene therapy approach.

We developed an in vivo gene therapy approach to characterize and optimize the anti-angiogenic activity of class I interferons (IFNs), using packaging cell lines producing an amphotropic LXSN-based retrovirus expressing either IFN-alpha1 (alpha1Am12), IFN-beta (betaAm12) murine cDNAs, or the vector alone (neoAm12). Pretreatment of endothelial-like Eahy926 cells in vitro with conditioned media (CM) from alpha1Am12 or betaAm12 cells for 48 hours significantly inhibited their migration and invasion as compared to neoAm12-CM-treated cells. betaAm12-CM also inhibited the formation of capillary-like structures on Matrigel by EAhy926 cells. In vivo, inclusion of the betaAm12 cells strongly inhibited, and alpha1Am12 partially inhibited, the angiogenic response in the Matrigel sponge model in both immune-competent and athymic nude mice. Electron microscopy showed a reduction of host cell infiltration in alpha1Am12- and betaAm12-containing sponges and reduction of invading tubular clefts of host cells as compared to controls. Finally, inoculation of either alpha1Am12 or betaAm12 cells (10%) along with a highly angiogenic Kaposi's sarcoma cell line (90%) resulted in a powerful reduction of tumor growth in nude mice in vivo, as did infection with the interferon-alpha-producing retroviruses. These data suggest that a gene therapy approach using class I interferons can effectively inhibit tumor angiogenesis and growth of vascular tumors.

Animals↗

Modulation of metastasis phenotypes of non-small cell lung cancer cells by 17-allylamino 17-demethoxy geldanamycin.

BACKGROUND: Cancer cells that overexpress c-erbB oncogenes exhibit resistance to chemotherapy, enhanced tumorigenicity, as well as increased propensity for metastasis. The aim of this study was to investigate if depletion of erbB-1/EGFR and erbB-2/HER2neu oncogene products by 17-allylamino 17-demethoxy Geldanamycin (17AAGA) could diminish the metastatic potential of non-small cell lung cancer (NSCLC) cells that express varying levels of the erbB1/erbB2 oncogenes. METHODS: NSCLC cell lines (H460, H358, H322, or H661) were assayed for expression of erbB1 and erbB2, the cell adhesion molecule E-cadherin, secretion of the matrix metalloproteinase 9 (MMP-9), and vascular endothelial cell growth factor (VEGF), as well as their ability to invade Matrigel after 48-hour exposure to 17AAGA. RESULTS: 17AAGA significantly depleted erbB1 or erbB2 levels in NSCLC cells expressing high levels of these proteins, and effectively inhibited their growth with IC50 values ranging from 50 to 90 nmol/L. Moreover, drug treatment enhanced E-cadherin expression in H322 and H358 cells, and inhibited secretion of MMP-9 and VEGF secretion by tumor cells. 17AAGA diminished hypoxia-induced upregulation of VEGF expression as well as growth factor-mediated augmentation of MMP-9 secretion, and profoundly inhibited the ability of H322 and H358 cells to migrate through Matrigel in response to chemoattractants. CONCLUSIONS: In addition to its known antiproliferative and chemosensitization effects, 17AAGA inhibits the metastatic phenotype of lung cancer cells. 17AAGA may be a novel pharmacologic agent for specific molecular intervention in lung cancer patients.

Benzoquinones↗

Dimethylarginine dimethylaminohydrolase activity modulates ADMA levels, VEGF expression, and cell phenotype.

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and is metabolised by dimethylarginine dimethylaminohydrolase (DDAH). Elevated levels of circulating ADMA correlate with various cardiovascular pathologies less is known about the cellular effects of altered DDAH activity. We modified DDAH activity in cells and measured the changes in ADMA levels, morphological phenotypes on Matrigel, and expression of vascular endothelial growth factor (VEGF). DDAH over-expressing ECV304 cells secreted less ADMA and when grown on Matrigel had enhanced tube formation compared to untransfected cells. VEGF mRNA levels were 2.1-fold higher in both ECV304 and murine endothelial cells (sEnd.1) over-expressing DDAH. In addition the DDAH inhibitor, S-2-amino-4(3-methylguanidino)butanoic acid (4124W 1mM), markedly reduced human umbilical vein endothelial cell tube formation in vitro. We have found that upregulating DDAH activity lowers ADMA levels, increases the levels of VEGF mRNA in endothelial cells, and enhances tube formation in an in vitro model, whilst blockade of DDAH reduces tube formation.

Amidohydrolases↗

Coexpression of endothelial markers and CD14 by cytokine mobilized CD34+ cells under angiogenic stimulation.

OBJECTIVE: A subset of adult peripheral blood leukocytes functions as endothelial progenitor cells that incorporate into the vasculature in animal models of neovascularization. The basic mechanisms by which differentiation proceeds are still unclear. This study analyses the in vitro differentiation of cytokine mobilized, human CD34(+) cells. METHODS: Granulocyte-monocyte colony stimulating factor mobilized human CD34(+) cells were isolated and grown in culture in the presence of vascular endothelial growth factor (50 ng/ml) and basic fibroblast growth factor (10 ng/ml). Their differentiation was followed using cytological and immunohistochemical techniques. Fibronectin-coated culture dishes or three-dimensional cultures were used. RESULTS: CD34(+) cells grown on fibronectin-coated dishes differentiated along the granulocytic and monocytic/macrophage lineages with no evidence for an endothelial cell differentiation. CD14(+) macrophages appeared in long-term culture and then acquired endothelial cell markers such as VE-cadherin, the endothelial form of NO synthase and the von Willebrand factor. Yet they were unable to form tubular structures in Matrigel. Only typical macrophages were observed in Matrigel. CONCLUSION: Angiogenic stimulation of CD34(+) precursor cells leads to cells that expressed mixed macrophage and endothelial cell properties. They could represent an intermediate phenotype in the pathway that leads to mature endothelial cells.

Adult↗

Evaluation of the effect of culture matrices on induction of CYP3A isoforms in cultured porcine hepatocytes.

Several bioartificial liver devices have been developed as temporary therapy for patients suffering from fulminant hepatic failure. Some of these devices contain porcine hepatocytes entrapped in collagen matrices. In order to improve the function of these BAL devices, there exists a need to optimize metabolic function of cultured hepatocytes. The goal of these investigations was to evaluate the effect of altering culture conditions on rifampin-mediated induction of CYP3A isoforms in cultured porcine hepatocytes. Midazolam metabolism was compared in porcine hepatocytes cultured in a monolayer configuration on collagen gels, in a sandwich configuration between collagen gels and a Matrigel overlay, and in spheroidal cultures. The effect of culture conditions was evaluated, by measuring CYP3A-mediated metabolism of midazolam and by immunoblotting to detect CYP3A proteins, in control cultures and in rifampin-treated cultures. Results obtained by normalizing the metabolism rate data to cell numbers (based on DNA content) present at the end of the culture experiment, showed that there was no difference between the different culture conditions tested. Our results suggest that culturing porcine hepatocytes as spheroids or in a sandwich configuration between collagen and Matrigel, offers no advantage in terms of CYP3A-mediated metabolic function on a per cell basis compared to culturing on collagen gels.

Animals↗

KR-31372 inhibits KDR/Flk-1 tyrosine phosphorylation via K+(ATP) channel opening in its antiangiogenic effect.

The aim of this study was to identify the signaling pathway of the antiangiogenesis by (2R,3R,4S)-N-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl 2H-1-benzopyran-4yl)-N'-benzylguanidine (KR-31372). KR-31372 inhibited the in vitro basal tube formation using Matrigel-coated plate and in vivo neovascularizations in mice induced by Matrigel containing vascular endothelial growth factor (VEGF(165), 5 ng/ml). VEGF(165) markedly increased cell proliferation using 5-bromo-2'-deoxyuridine incorporation and chemotactic migration using transwell chamber in human umbilical vein endothelial cells, those of which were significantly suppressed by pretreatment with KR-31372 and levcromakalim concentration dependently. The suppression of all these variables were strongly antagonized by glibenclamide, ATP-sensitive K(+) channel blocker. KR-31372 (10(-6)-10(-4) M) and levcromakalim (10(-5) M) concentration-dependently suppressed the VEGF(165)-induced increases in KDR/Flk-1 tyrosine phosphorylation as well as the extracellular signal-related kinase 1/2 (ERK1/2), p38 MAK and p125(FAK) tyrosine phosphorylation. These variables were significantly antagonized by glibenclamide. In conclusion, KR-31372 significantly inhibited the KDR/Flk-1 tyrosine phosphorylation-linked ERK1/2, p38 MAPK and p125(FAK) tyrosine phosphorylation via mediation of K(+)(ATP) channel opening, thereby resulting in antiangiogenesis.

Adenosine Triphosphate↗

The SHB adapter protein is required for efficient multilineage differentiation of mouse embryonic stem cells.

The SH2 domain-containing adapter protein SHB transmits signals from receptor tyrosine kinases regulating diverse processes such as apoptosis and differentiation. To elucidate a role for SHB in cell differentiation, wild-type and R522K (inactive SH2 domain-mutant) SHB were transfected and expressed in mouse embryonic stem (ES) cells. Microarray analysis using Affymetrix U74A chips on undifferentiated ES cells and expression of selected differentiation markers after generation of embryoid bodies were subsequently assessed. Wild-type SHB altered the expression of 16 genes in undifferentiated ES cells, many of which have been found to relate to neural cell function. R522K-SHB altered the expression of 128 genes in undifferentiated ES cells, the majority of which were decreased, including several transcription factors related to development. When grown as embryoid bodies, after 4 days R522K-SHB ES cells were already found to display a different morphological appearance, with an impaired cavity formation that occurred in the absence of altered OCT4 expression. This impairment was reversed by exogenous addition of Matrigel. In addition, R522K-SHB embryoid bodies displayed reduced mRNA contents of the liver protein albumin, the pancreatic proteins amylase, glucagon and insulin after 20 days of differentiation. Matrigel did not restore the impaired expression of albumin in the R522K-SHB cells. Expression of the mesodermal marker cardiac actin and the neural marker neurofilament heavy chain alpha was not affected by wild-type or R522K-SHB overexpression. It is concluded that SHB is required for efficient differentiation of ES cells into embryoid bodies with normal cavities and cells belonging to endodermal lineages.

Adaptor Proteins, Signal Transducing↗

Intact aggrecan and chondroitin sulfate-depleted aggrecan core glycoprotein inhibit axon growth in the adult rat spinal cord.

Aggrecan is a chondroitin sulfate (CS)/keratan sulfate (KS)-substituted proteoglycan (PG) abundant in cartilage which is also present within the mammalian embryonic, adult, and injured adult central nervous system (CNS). Although its role within the CNS is not clear, cell culture studies show that when substituted with CS, aggrecan inhibits neurite extension. To better understand the inhibitory effect of aggrecan on injured adult axons in vivo, we developed a model to independently test intact aggrecan and CS-depleted aggrecan core glycoprotein. Acute rat spinal cord hemisection cavities were filled with a growth-promoting matrix, Matrigel, and severed dorsal rootlets were placed into this matrix. This created an assay in which axons readily grew. The extent of ingrowth in this baseline assay was compared to the ingrowth in Matrigel loaded with intact aggrecan or the purified core glycoprotein of aggrecan. Our results show that both intact aggrecan and equivalent concentrations of the core glycoprotein component significantly inhibit axonal growth in this model system. These results confirm that aggrecan can inhibit the growth of adult axons in vivo and suggest that the inhibitory effects of aggrecan may be mediated, at least in part, by structures located on the core glycoprotein in the absence of the bulk of the CS chains.

Aggrecans↗

A novel basement membrane-induced gene identified in the human endometrial adenocarcinoma cell line HEC1B.

Cultured HEC1B human endometrial adenocarcinoma cells respond to reconstituted basement membrane (Matrigel) by morphological and functional differentiation in vitro. Our goal is to identify genes involved in this differentiation process. By means of rt-PCR, we were able to isolate the novel 2.4 kb Matrigel-induced transcript icb-1 containing an open reading frame predicting a 31.7 kDa protein. The time-dependent induction of icb-1 gene expression by basement membrane was confirmed by Northern blot experiments. In a data bank search, several EST homologues corresponding to the 3' untranslated region could be found. In summary, icb-1 as a new tool enables us to study molecular mechanisms of cell-matrix interactions contributing to carcinogenesis.

Amino Acid Sequence↗

Overexpression of pp60c-src elicits invasive behavior in rat colon epithelial cells.

BACKGROUND & AIMS: Src activation is reported as an early event found in preneoplastic colonic adenomas and in 70% of colon carcinomas. The aim of this study was to identify the biological consequences of c-src overexpression in rat colon epithelial cells. METHODS: Introduction and overexpression of c-src in an immortalized rat colon epithelial cell line was achieved using lipofection. Transfectants were tested for changes in growth and cell behavior using different in vitro assay systems. RESULTS: Colon epithelial cells overexpressing c-src showed the ability to form microcolonies in soft agar without acquiring tumorigenic potential. In in vitro assays, c-src transfectants displayed a gain of invasive potential through Matrigel without an accompanying change in migrational ability. No discernible qualitative changes were observed in the phosphotyrosyl protein profile between c-src and v-src transfectants. Assessment of the cadherin/catenin status in these cells revealed an intact, functional complex with no detectable tyrosine phosphorylation of different components of the complex. CONCLUSIONS: Overexpression of c-src in an immortalized rat colon epithelial cell line does not elicit full neoplastic transformation but enhances anchorage-independent growth and confers invasion capability. Increased invasion through Matrigel was not linked to inactivation of the cadherin complex in c-src transfectants.

Animals↗

Epidermal growth factor stimulation can substitute for c-Src overexpression in promoting breast carcinoma invasion.

BACKGROUND AND AIMS: Cancer progression is in large part dependent on the complex process of cell invasion, involving adhesion, motility, and enzymatic proteolysis. Overexpression of the Src proto-oncogene (c-Src), a nonreceptor tyrosine kinase, has been implicated in the progression of both colon and breast cancer. Our group has previously reported that overexpression of c-Src leads to a significant gain in invasive cell behavior in vitro. In this study, we sought to assess the relative importance of epidermal growth factor (EGF) stimulation and c-Src overexpression in conferring an invasive phenotype. METHODS: Breast carcinoma cells and colon epithelial cells which naturally express low levels of c-Src were used for these studies. The cells were transfected so that they overexpressed c-Src; the mock-transfected parent lines were used as controls. Transfectants were tested for changes in invasion patterns after Src inhibition and EGF stimulation. RESULTS: Invasion assays in both cell systems confirmed the importance of c-Src in determining invasive potential. A significant correlation was shown between c-Src kinase protein and cell invasion. Furthermore, Src inhibition significantly inhibited invasion in a dose-dependent manner. To clarify the relative contribution of EGF and c-Src to cell invasion, the ability of cells to invade through growth-factor-reduced matrigel, with or without EGF added, was compared to invasion through intact matrigel. The breast and colon cell lines behave quite differently in this regard. In the colon model, overexpressed c-Src is critical for cell invasion and stimulation with EGF is synergistic with c-Src overexpression. Conversely, the breast carcinoma cells transfected with c-Src were unable to invade without EGF stimulation and did not demonstrate the same synergistic relationship between c-Src and EGF. Instead, our results indicate that in BT474 breast carcinoma cells, EGF can substitute for c-Src in promoting breast cancer cell invasion. CONCLUSIONS: Because most breast carcinomas overexpress c-Src, it behooves one to question the extent to which reducing the amount of EGF and consequent EGFR activity will decrease invasion. In this study, the effects of EGF on cell invasion were determined in light of a single alteration in c-Src expression. Our results show that EGF enhances the impact of c-Src overexpression on invasion. In breast cancer cells, EGF is capable of inducing invasion to the same extent as c-Src overexpression. This suggests that anti-EGFR therapies will be efficacious in retarding breast carcinoma invasion and metastasis.

Animals↗

Focal adhesions and associated proteins in medullary thyroid carcinoma cells.

BACKGROUND: In medullary thyroid carcinoma (MTC), mutations in the RET protooncogene lead to oncogenic transformation. RET activation in other cell types has been shown to cause phosphorylation of the focal adhesion-associated proteins focal adhesion kinase (FAK), paxillin, and p130(CAS). We hypothesized that adhesion-dependent signaling might be deranged in MTC cells. METHODS: Indirect immunofluorescence was used to label beta(1) integrin, FAK, paxillin, and p130CAS. Rhodamine-labeled phalloidin was used to visualize actin microfilaments. Phosphorylated protein was detected by immunoprecipitation followed by Western blotting for phosphotyrosine. MTC cell invasiveness was quantified using a modified Boyden chamber assay. RESULTS: Clustering of beta(1) integrin, FAK, paxillin, and p130(CAS) into focal adhesions were not detected in MTC cells under any conditions, although clustering was seen as expected in control HeLa cells. Despite this failure, FAK, paxillin and p130(CAS) were all found to be phosphorylated. Actin microfilaments were generally not seen although in a few cells, small, poorly formed microfilaments could be detected. MTC cells invaded poorly as compared with highly invasive cell lines. However a clear difference was noted between invasiveness on growth factor depleted Matrigel and regular Matrigel. CONCLUSIONS: In MTC cells, focal adhesions are not seen in response to interaction with extracellular matrix. Consistent with this failure, actin microfilaments are absent or poorly formed and invasion is weak. Despite the absence of focal adhesions, focal adhesion proteins remain phosphorylated, even though in normal cells their signaling activity is dependent on focal adhesion formation. Deranged adhesion-dependent signaling may contribute to MTC pathogenesis.

Actin Cytoskeleton↗

Effects of epidermal growth factor on the invasion activity of the bladder cancer cell line.

PURPOSE: Epidermal growth factor (EGF) is excreted in high concentrations in the urine and stimulates urothelial cell growth. The cultured bladder cancer cell line KU-1 was used to study the molecular mechanisms by which EGF affects urothelial tumor growth and invasion activity. MATERIALS AND METHODS: KU-1 cells were grown in cell culture in the presence or absence of EGF. Anchorage-independent cell growth assays and Matrigel invasion assays were performed. Expression of cytokeratins was examined by Northern and Western blot analyses. Chloramphenicol acetyltransferase assays were used to determine whether EGF stimulated matrix metalloproteinase expression. RESULTS: EGF enhanced anchorage-independent growth in soft agar and increased the number of cells penetrating into a Matrigel membrane. A transient transfection assay revealed that EGF increased the promoter activities of the matrix metalloproteinase 1 and 9 genes in KU-1 cells. Moreover, the morphology of KU-1 cells changed after the addition of EGF to the culture medium. Western and Northern blot analyses demonstrated that EGF decreased cytokeratin 19 expression, but did not affect expression of cytokeratin 8 or 18. CONCLUSION: EGF increased the invasive activity of KU-1 bladder cancer cells in part by increasing the secretion of matrix metalloproteinases. Morphologic changes may result from altered composition of cytoskeletal proteins.

Epidermal Growth Factor↗

Exposure to alkyllysophospholipids inhibits in vitro invasion of transitional cell carcinoma.

Alkyllysophospholipids (ALP) are a group of synthetic analogs of a naturally occurring 2-lysophosphocholine. They are directly cytotoxic to a variety of neoplastic cell lines and can modulate the activation of macrophages against tumor cells. Moreover, recent reports have demonstrated the ability of racemic 1-octadecyl-2-methyl-sn-glycero-3-phosphocholine (ET-18-O-CH3) to prevent tumor cell invasion when given in noncytotoxic concentrations. Using an in vitro model, we studied the ability of ET-18-O-CH3 to prevent transitional cell carcinoma invasion. Cytostatic activity was determined by clonal growth assay (25,000 cells per plate). Suppression of colony growth was found at concentrations greater than 4 micrograms/ml. of ET-18-O-CH3 in rat and mouse transitional cell carcinoma (TCC) cell lines and greater than 2 micrograms/ml. in a human TCC line. Inhibition of tumor cell invasion was assessed by the effects on cell migration through Matrigel-coated 8 microns-pore polycarbonate filters (using 1 x 10(5) cells per chamber). Invasion was reduced to 50 to 70% of controls in both the mouse and rat TCC lines at the highest concentration (4.0 micrograms/ml.). In the human TCC line, invasion was reduced to less than 30% of controls at concentrations as low as 0.5 micrograms/ml. Motility (without invasion) of the human TCC line, as measured by cell migration through the micropore filter without the Matrigel coating, was inhibited at the same concentration of ET-18-O-CH3 found to inhibit invasion. The anti-invasive effect seen with noncytotoxic concentrations of ALP may prove useful in the treatment of transitional cell carcinoma.

Animals↗

Entubulization repair of severed cavernous nerves in the rat resulting in return of erectile function.

Erectile dysfunction is a significant complication of radical pelvic surgery in men. Using the rat as an experimental model, we investigated the feasibility of repairing surgically ablated cavernous nerves utilizing silastic tube nerve growth conduits filled with nerve growth enhancing media. Known fertile male Sprague-Dawley rats were randomly divided into four surgical groups consisting of nerve ablation, immediate nerve reconstruction utilizing the entubulization technique (two groups) and control. The nerve ablation group had five mm. sections of the cavernosal nerve excised bilaterally. The entubulization nerve graft group had five mm. sections of the cavernous nerve excised bilaterally, followed by immediate microsurgical reconstruction with a silastic nerve tube conduit filled with either Matrigel and heparin (MA) or Matrigel and heparin plus acidic fibroblast growth factor (MA/aFGF), interposed between the severed cavernous nerve stumps bilaterally. The control group underwent sham operations with the cavernous nerves being exposed only. Erectile function was evaluated at one, two, and four months postoperatively. Return of erectile function was defined as tumescence of the corporal bodies with application of direct electrical stimulation (four volts of five millisecond pulses at 20 Hertz) to the proximal cavernous nerves. The two and four month electrical stimulation studies resulted in tumescence from 50% and 58% of the entubulization nerve reconstructed nerves with MA/aFGF versus 29% and 30% for the MA only group and only 5% and 11% for the ablated group, respectively. We conclude that in this experimental model immediate nerve graft repair utilizing entubulization techniques with the addition of nerve growth enhancing media appears to be a successful method of salvaging erectile function when the cavernous nerves have been divided.

Animals↗

Type IV procollagen mRNA regulation: evidence for extracellular matrix/cytoskeleton/nuclear matrix interactions in human urothelium.

The absence of basement membrane components correlates with tumor stage and progression in human bladder cancers. We have previously shown that invasive tumors possess the ability to degrade basement membrane. However, the presence of basement membrane may be affected not only by its degradation, but by its synthesis and deposition as well. Our results in the present study suggest that while the invasive human transitional carcinoma cell line EJ has an increased amount of type IV procollagen mRNA when compared to the non-invasive RT4 cell line, type IV collagen staining is absent in the invasive EJ cells and intensely present in the non-invasive RT4 cells. Moreover, when EJ cells were grown on an artificial basement membrane (Matrigel), type IV procollagen mRNA expression was down-regulated to the levels seen with the non-invasive RT4 cells. We also discovered that the invasive cells, when grown on Matrigel, appeared morphologically different from the same cells grown on plastic tissue cultures. We conclude that a deficient basement membrane in invasive cancer cells may be due not only to active proteolytic activity but also to an abnormal production and deposition of extracellular matrix components. In addition, we also demonstrated that basement membrane components may have a significant effect on epithelial cell morphology and gene regulation, and that any alterations of the extracellular matrix-cytoskeleton-nuclear matrix interactions can lead to altered gene regulations and cell function.

Basement Membrane↗