Hepatocyte growth factor is an invasion/migration factor of rat urothelial carcinoma cells in vitro

Hepatocyte growth factor (HGF) plays an important role in the growth, progression and angiogenesis of various tumors. It is reported that patients with urinary bladder cancer have elevated levels of HGF in urine and that bladder cancer tissue contains an increased amount of HGF. Thus, the data suggest a functional role of HGF in urinary bladder cancer. We evaluated the mechanistic role of HGF in urinary bladder carcinoma in vitro using the rat urothelial cell lines MYP3 (anchorage-dependent and non-tumorigenic in athymic nude mice), LMC19, MYU3L, T6 and AS-HTB1 (anchorage-independent and tumorigenic). The HGF receptor c-met was expressed by all of the cell lines, as determined by northern blot. In MYP3 cells, HGF strongly stimulated anchorage-dependent growth, but not migration, invasion or secretion of matrix metalloproteinases (MMPs). In LMC19, T6 and AS-HTB1 cells, HGF stimulated migration, invasion and secretion of MMPs. Anchorage-dependent growth stimulation was limited to AS-HTB1 cells. MYU3L cells were refractory to HGF in both growth and invasion assays. However, a neutralizing antibody and an anti-sense oligonucleotide to HGF partially inhibited the growth only of MYU3L cells, the finding being indicative of an autocrine stimulatory mechanism. HGF mRNA expression and protein synthesis were induced in bladder stromal cells by the conditioned medium of carcinoma cell lines, and IL-1beta and basic fibroblast growth factor were identified as cancer cell-derived HGF-releasing factors. These results suggest that HGF acts as a mitogen in a non-tumorigenic cell line, whereas in tumorigenic cell lines it acts as an invasion and migration factor by either a paracrine or an autocrine mechanism.

Transcriptional targeting of herpes simplex virus for cell-specific replication

Tissue- or cell-specific targeting of vectors is critical to the success of gene therapy. We describe a novel approach to virus-mediated gene therapy, where viral replication and associated cytotoxicity are limited to a specific cell type by the regulated expression of an essential immediate-early viral gene product. This is illustrated with a herpes simplex virus type 1 (HSV-1) vector (G92A) whose growth is restricted to albumin-expressing cells. G92A was constructed by inserting an albumin enhancer/promoter-ICP4 transgene into the thymidine kinase gene of mutant HSV-1 d120, deleted for both copies of the ICP4 gene. This vector also contains the Escherichia coli lacZ gene under control of the thymidine kinase promoter, a viral early promoter, to permit easy detection of infected cells containing replicating vector. In the adult, albumin is expressed uniquely in the liver and in hepatocellular carcinoma and is transcriptionally regulated. The plaquing efficiency of G92A is > 10(3) times higher on human hepatoma cells than on non-albumin-expressing human cells. The growth kinetics of G92A in albumin-expressing cells is delayed compared with that of wild-type HSV-1, likely due to aberrant expression of ICP4 protein. Cells undergoing a productive infection expressed detectable levels of ICP4 protein, as well as the reporter gene product beta-galactosidase. Confining a productive, cytotoxic viral infection to a specific cell type should be useful for tumor therapy and the ablation of specific cell types for the generation of animal models of disease.

Effect of selenium on lead-induced alterations in rat brain

The effects of lead (Pb) and selenium (Se) interactions on central nervous system (CNS) functions were seen in adult rats by both biochemical and histologic pathological alterations. Pb administration of 20 mg/kg body wt for 8 wk showed degenerative changes only in the cerebral cortex. The changes in the cerebellar regions were not significant. Biochemically a marked decrease in the DNA, RNA, and protein content was seen following lead treatment. These decreases were significant in both the regions of the brain. During the concomitant administration of Pb and Se, the alterations in the transverse section of cerebral cortex showed only marginal changes. The values of DNA and RNA content showed significant improvement in both regions of the brain compared to the Pb treated group.

Hepatocyte growth factor and its receptor are expressed in cardiac myocytes during early cardiogenesis

In the mouse, the heart primordium arises when mesoderm is set aside during gastrulation, is induced by pharyngeal endoderm, migrates ventrally to the midline of the embryo, forms a tube, and begins beating. Little is known of the molecular mechanisms that mediate the determination, mitosis, differentiation, and migration that lead to the beating heart. Transcripts for hepatocyte growth factor/scatter factor (HGF) and its receptor are coexpressed transiently and dynamically in the premyocardium but not in other heart progenitor cells. Transcripts the HGF ligand and receptor are first detected before cardiac function and looping and persist through the first looping stage, when heart morphology begins to elaborate. HGF ligand and receptor mRNA are detectable after the putative heart transcription factor, Csx/Nkx2-5, and concomitantly with the heart structural gene, cardiac actin. HGF receptor mRNA is detected in the mesoderm of the headfold stage and persists in myocardial precursors of the ventricles and atria (but not in the outflow-tract smooth muscle cells) through the 14-somite stage at approximately 8.75 days after fertilization (day E8.75). At the headfold stage, between E7.5 and E8.0, HGF receptor mRNA was detected in myocardial cells before fusion at the ventral midline. HGF ligand and receptor mRNA transcripts are coexpressed in the embryo, except in the headfold state (when only the HGF receptor can be detected) and in the heart at the 14- to 18-somite stage (when only HGF ligand can be detected). The dynamic pattern of coexpression suggests an autoregulatory role for HGF and its receptor in early heart development.

Selective tumorigenesis in non-parenchymal liver epithelial cell lines by hepatocyte growth factor transfection

Hepatocyte growth factor (HGF) has been recently suggested to contribute to tumorigenesis by an autocrine mechanism in fibroblast cells overexpressing its receptor, the MET/HGFR protein. Since epithelial cells represent the primary physiologic target of HGF, we investigated whether inappropriate expression of HGF by epithelial cells which normally express MET/HGFR may also contribute to tumorigenesis. We have transfected a full length rat HGF gene into three mouse epithelial cell lines, one derived from breast (MM55) and two (BNL CL.2 and NMuLi) representing liver non-parenchymal epithelial cells (NPEC). We confirmed the presence of the transfected gene by Southern blot analysis, the production of HGF protein by immunofluorescence, and the preservation of HGF biologic activity by bio-assay. In comparison to untransfected cells, all three HGF-transfected cell lines displayed high level MET/HGFR autophosphorylation and increased ability to proliferate in media containing low serum. The two HGF-transfected liver NPEC lines, but not the HGF-transfected mammary cell line, displayed loss of cell contact growth-inhibition and acquired a markedly increased ability to form colonies in soft agar. Furthermore, the NPEC HGF-transfected cell lines formed much larger tumors in nude mice than the untransfected counterparts, with extensive invasion and sporadic lung metastases. These results demonstrate that overexpression of HGF in at least some epithelial cells contribute to tumorigenesis, and furthermore suggest a possible role for the HGF-MET/HGFR system in the progression of certain epithelial tumors.

Hepatocyte growth factor-induced signal transduction in two normal mouse epithelial cell lines

We have investigated HGF-induced signal transduction in two normal mouse epithelial cell lines (M23 and MM55). Both cell lines display HGF-induced mitogenesis and high level HGF-induced autophosphorylation of MET/HGFR. In both M23 and MM55 cells, HGF induces association with MET/HGFR and increased tyrosine phosphorylation of the SH2-domain containing proteins PI3K, GAP and NCK. PLC-gamma exhibited neither HGF-induced increases in tyrosine phosphorylation nor an association with MET/HGFR in these cell lines. Additionally, HGF induced increased transcription of c-fos, c-jun, junB, junD, and c-myc early response genes in both cell lines. We therefore suggest that the second messenger proteins PI3K, GAP and NCK, and possibly the protein products of the c-fos, c-jun, junB, junD and c-myc genes, are important elements in the HGF-induced mitogenic pathway in the normal mouse epithelial cell lines M23 and MM55.

Digital monitoring of sleep-disordered breathing using snoring sound and arterial oxygen saturation

A new portable digital recorder (SNORESAT) that uses the sound of snoring and arterial oxygen saturation (SaO2) to monitor breathing abnormalities during sleep was constructed and compared in the laboratory with standard overnight polysomnography (PSG). The device digitally records sound from a transducer applied to the chest and SaO2 from a commercially available ear oximeter. A snore is identified when the moving time average of the sound exceeds a threshold voltage level longer than 0.26 s. The stored data are transferred to a personal computer for poststudy analysis. An analysis algorithm identifies a respiratory disturbance event when a quiet period of 10 to 120 s separates two snores and is associated with a fall in SaO2 exceeding 3%. The respiratory disturbance index (RDI), mean apnea duration, mean lowest SaO2, and number of desaturations > 3% are computed. A total of 129 referrals to the sleep apnea outpatient clinic underwent simultaneous all-night recording of PSG and SNORESAT. Using the computed RDI recorded by the SNORESAT, the sensitivity and specificity of the monitor in detecting sleep apnea syndrome (SAS) ranged between 84 and 90% and 95 and 98%, respectively, depending on the PSG value of RDI used to define SAS (range, > or = 7 to > or = 20 events/h). Using a PSG value of RDI > or = 10, or > or = 20 RD/h as the definition for SAS, the prevalence of SAS in the referral population was 45 and 31%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatocyte growth factor induces proliferation and morphogenesis in nonparenchymal epithelial liver cells

Hepatocyte growth factor is the most potent mitogen known for hepatocytes, and increasing evidence suggests that hepatocyte growth factor plays an important role in liver regeneration. However, hepatocytes are not the only liver epithelial cell population that proliferates during regeneration. Experimental and clinical data indicate that the regenerative liver response also includes the participation of nonparenchymal epithelial cells. The possible role of hepatocyte growth factor in this nonparenchymal epithelial cell regenerative response has not been explored. We studied the effects of hepatocyte growth factor with a model of two normal mouse nonparenchymal epithelial cell-derived cell lines with varying differentiation potentials. Addition of hepatocyte growth factor induced mitogenesis and scattering of colonies growing on culture dishes in both cell lines. Furthermore, hepatocyte growth factor was found to exert a profound morphogenic effect on cells growing in collagen matrixes. Hepatocyte growth factor-treated embryonic BNL CL.2 cell colonies developed elaborately branching elongated cords with only minimal tubularization. Hepatocyte growth factor-treated postnatal NMuLi cell colonies developed a network of anastomosing tubules with wide lumens. These morphological changes were not inhibitable by transforming growth factor-beta and were not induced by other hepatocellular growth factors including epidermal growth factor, transforming growth factor-alpha, acidic fibroblast growth factor and insulin. Histological sections of the hepatocyte growth factor-treated BNL CL.2 cell colonies resembled neocholangioles, believed to include facultative stem cells, which proliferate after submassive and massive hepatic necrosis. Sections of hepatocyte growth factor-treated NMuLi colonies resembled ductules proliferating in biliary tract obstruction from a wide variety of causes. This work represents the first examples of hepatocyte growth factor-induced mitogenesis, scattering and morphogenesis in the same cell lines. More important, our data suggest that hepatocyte growth factor mediates liver response to injury not only by acting on hepatocytes but also by exerting mitogenic and morphogenic influences on nonparenchymal epithelial cell components.

Circular-harmonic function, minimum average correlation energy filters

New distortion-invariant correlation filters for in-plane rotation invariance are considered. These use circular-harmonic functions combined with minimum-average correlation-plane filter techniques. Various circular-harmonic function shortcomings are quantified.

Structure, tissue-specific expression, and transforming activity of the mouse met protooncogene

A 6.7-kilobase met complementary DNA (cDNA) was isolated from a pcD cDNA library prepared from C3H mouse fibroblast cell line polyadenylated RNA. Sequence analysis of 6.7-kilobase met cDNA insert revealed that it contained the entire open reading frame and shared an overall homology of 88.1% with the human met gene. Using the mouse met cDNA as probe, high levels of met expression were observed in the kidney, brain, lung, skin, and embryonic tissue as well as in several factor responsive mouse myeloid cell lines. Under SV40 promoter control, the mouse met protooncogene cDNA in the pCD vector was able to transform NIH 3T3 cells. These transformed cells possess multiple copies of mouse met cDNA and exhibit properties of malignant cells, including growth in soft agar and induction of tumors in nude mice. Tumor explant cell lines analyzed by Western blot also reveal the presence of high levels of Mr 170,000 and 140,000 met protein product(s).

c-mos proto-oncogene RNA transcripts in mouse tissues: structural features, developmental regulation, and localization in specific cell types

c-mos RNA transcripts have been previously detected in mouse gonadal tissue and in late-term embryos. Here, we show that they are also present at low levels in placenta and in adult mouse brain, kidney, mammary gland, and epididymis. Marked differences are observed in the size of the mos RNA transcripts detected in different tissues. All transcripts appear to end at the same 3' position, and the tissue-specific size variations appear to be due to the use of different promoters. For example, the testicular and ovarian RNA transcripts initiate approximately 280 and approximately 70 base pairs, respectively, upstream from the first initiation codon, but both end at a common site downstream from the mos open reading frame. The expression of mos is developmentally regulated in gonadal tissue. Thus, the level of mos transcripts in testes is low for the first 3 weeks after birth, increases at least 10-fold around day 25, and reaches adult levels by day 30. In contrast, ovaries from preweaning mice contain a higher level of mos mRNA compared to ovaries from adult mice. In cell fractionation experiments we show that mos transcripts are present in haploid germ cells. We find that these transcripts are associated with monosomes and polysomes. The peculiar pattern of mos expression in mouse gonadal tissue suggests a role for the c-mos proto-oncogene in germ cell differentiation.