Age-dependent induction of hepatic tumor regression by the tissue microenvironment after transplantation of neoplastically transformed rat liver epithelial cells into the liver

Age is the biggest risk factor associated with the development of cancer. Whereas the incidence of neoplastic disease increases dramatically in aging humans and experimental animals, the effects of aging on tumorigenesis are poorly understood. Using a rodent model, we have previously shown that the microenvironment of the hepatic parenchyma regulates hepatic tumor formation from transplanted neoplastic cells in an age-dependent manner. In the current study, we have investigated the mechanistic basis for the age-dependent suppression of tumor formation by transplanted BAG2-GN6TF rat liver epithelial tumor cells. Examination of liver tissue at 7 and 14 days after transplantation of liver tumor cells revealed the presence of injection-site tumors in both young and old animals. With time, these tumors spontaneously regressed from young adult livers, leaving no tumor remnant and without evidence of injury to the parenchyma. In contrast, tumors detected in old animals at early time points after transplantation persisted for the remainder of the life of the host. Reduced cell proliferation and increased apoptotic cell death were detected in hepatic tumors in young rats relative to hepatic tumors in old rats. These observations suggest that the regression of hepatic tumors from young rats was the direct result of an increased ratio of cell death to cell birth, whereas the persistence and expansion of hepatic tumors in old rats was related to increased cell proliferation relative to cell death. Because young adult rats developed persistent (nonregressing) tumors after transplantation of BAG2-GN6TF cells to extrahepatic sites, the consistent regression of BAG2-GN6TF tumors from livers of young rats seemed to be largely a result of interactions between tumor cells and factors specific to the liver microenvironment. These data indicate that the hepatic microenvironment of young rats can negatively regulate the growth of transformed liver epithelial cells, but with increasing age, the ability of the hepatic microenvironment to suppress the growth of neoplastic tissue deteriorates. Age-associated alterations in tissue microenvironments may thus permit the development of tumors late in life.

Biochemical characterization and deletion analysis of recombinant human protein phosphatase 2C alpha

The use of protein phosphatase inhibitors has been instrumental in defining the intracellular roles of protein phosphatase 1 (PP1), PP2A and PP2B. Identification of the role of PP2C in vivo has been hampered, in part, by the unavailability of specific inhibitors. In order to facilitate the identification of novel and specific inhibitors of PP2C by random screening of compounds, and to further characterize this enzyme at the molecular level by site-directed mutagenesis and X-ray crystallography, we have expressed active recombinant human PP2C alpha (rPP2C alpha) in Escherichia coli. Biochemical characterization of rPP2C alpha showed that it could hydrolyse p-nitrophenyl phosphate (pNPP) although, in contrast with native PP2C, this was not stimulated by Mg2+. As with native PP2C, okadaic acid failed to inhibit rPP2C alpha, whereas 50 mM NaF dramatically inhibited its activity. An alignment of the amino acid sequence of AMP-activated protein kinase (AMPK) with those of other serine/threonine protein kinases around the regulatory phosphorylation site (subdomains VII-VIII) revealed a high degree of conservation. Phosphopeptides derived from this region of AMPK and containing the almost invariant threonine (Thr172 in AMPK) were found to be good substrates for rPP2C alpha. We also showed that rPP2C alpha can inactivate AMPK, but only in the presence of Mg2+. To define the regions of PP2C alpha important for catalytic activity, we expressed a number of truncated proteins based on the sequence and proposed domain structure of the PP2C alpha homologue from Paramecium tetraurelia. Deletion of 75 residues (9 kDa) from the C-terminus appeared to have little effect on the catalytic activity using pNPP, phosphopeptides or AMPK as substrates. This suggests that the residues important in catalysis lie elsewhere in the protein. A further deletion of the C-terminus led to a completely inactive and very poorly soluble protein.

Synthesis and activity of a novel series of 3-biarylquinuclidine squalene synthase inhibitors

Quinuclidines with a 3-biaryl substituent are a new class of potent, orally active squalene synthase (SQS) inhibitors. Variants around these rigid structures indicate key structural requirements for cationic SQS inhibitors. Thus the lower in vitro potency found for quinuclidines bearing 3-substituents, which did not overlay the biphenyl group of 3-(biphenyl-4-yl)-3-hydroxyquinuclidine (2) (IC50 = 16 nM, rat microsomal SQS), implied a directional requirement for the 3-substituent. Similarly, the lower potency of the 3-terphenyl analogue 6 (IC50 = 370 nM) indicated size constraints for this substituent. In compounds with a linking group between the quinuclidine and biphenyl ring, linking groups of lower lipophilicity were less well tolerated (e.g., 17, CH2CH2, IC50 = 5 nM vs 19, NHCO, IC50 = 1.2 microM). Replacement of the distal phenyl ring of 2 with a more polar pyridine heterocycle caused a reduction in in vitro potency. In general, good in vivo activity in the rat was restricted to 3-hydroxy analogues, with the 3-[4-(pyrid-4-yl)phenyl] derivative 39 (IC50 = 161 nM) showing the best inhibition (following oral dosing) of cholesterol biosynthesis from mevalonate (ED50 = 2.7 mg/kg).

The hepatitis B virus posttranscriptional regulatory element is composed of two subelements

The RNAs of the hepatitis B virus (HBV) contain a cis-acting regulatory element which facilitates the cytoplasmic localization of unspliced transcripts (J. Huang and T. J. Liang, Mol. Cell. Biol. 13:7476-7486, 1993, and Z. M. Huang and T. S. Yen, J. Virl. 68:3193-3199, 1994). Such localization is presumed to be mediated by cellular factors which interact with the element. The HBV posttranscriptional regulatory element (HBVPRE) can efficiently activate an RNA export reporter system in an orientation-dependent and position-independent manner. Deletion analysis reveals that the HBVPRE consists of two subelements which function synergistically. A synergistic effect was also observed when the 5' (PREalpha) or 3' (PREbeta) subelements were duplicated. The bipartite structure of the HBVPRE is reminiscent of reports that the high-affinity binding sites of the Rev-like proteins must be duplicated to function efficiently (M. Grone, E. Hoffmann, S. Berchtold, B.R. Cullen, and R. Grassmann, Virology 204:144-152, 1994; X. Huang, T.J. Hope, B.L. Bond, D. McDonald, K. Grahl, and T. G. Parslow, J. Virol. 65:2131-2134, 1991; and D. McDonald, T. J. Hope, and T. G. Parslow, J. Virol. 66:7232-7238, 1992).

Inhibition of squalene synthase of rat liver by novel 3' substituted quinuclidines

Squalene synthase (SQS) is a key enzyme in the biosynthetic pathway for cholesterol and is a target for improved agents to lower plasma levels of low-density lipoprotein (LDL). A series of novel 3' substituted quinuclidines have been discovered as inhibitors of the rat liver microsomal enzyme. In this study, we demonstrate the inhibitory effects in vitro and in vivo, of two examples of the series. When microsomes were preincubated with compounds, before addition of substrate, both 3-(biphenyl-4-yl)quinuclidine (BPQ) and 3-(biphenyl-4-yl)-3-hydroxyquinuclidine (BPQ-OH) were found to cause biphasic inhibition of the enzyme with apparent inhibition constants (K'i) for the sensitive phases of 12 nM and 15 nM, respectively. The K'i values for the insensitive phases were 1.8 microM and 2.9 microM, respectively. The two examples inhibited equally both steps of the SQS-catalysed reaction, as shown by parallel inhibition of 3H+ release and labelled squalene formation from [1-3H]farnesyl pyrophosphate (FPP). BPQ and BPQ-OH were shown to be inhibitors of hepatic sterol synthesis from mevalonate with ED50 values of 10.6 and 7.1 mg/kg, respectively, after acute oral administration to the rat. BPQ-OH was chosen for further study and, to determine its selectivity of effect on the mevalonate pathway in vivo, the effect of a dose of 70 mg/kg on the pattern of labelled mevalonate incorporation into the various lipid fractions of the rat liver was examined. As expected, the incorporation into squalene and sterol products was inhibited by about 70%. An appearance of label in fractions corresponding to farnesyl and geranylgeranylpyrophosphates, as well as the corresponding alcohols, was observed in treated but not control animals. In addition, the administration of compound resulted in the appearance of peaks of mevalonate-derived radioactivity in an acidic fraction believed to represent metabolites of farnesol. Such results are consistent with inhibition of the mevalonate pathway at, and not before, SQS. In contrast, there was a significant increase in the incorporation of labelled mevalonate into ubiquinone 10, and the synthesis of dolichols was apparently unchanged. The results suggest a specific effect of BPQ-OH on rat liver SQS. The compound is, therefore, an interesting lead for further investigation of this class of compounds.

Erythemal ultraviolet insolation in New Zealand at solar zenith angles of 30 and 45

Solar UV radiometers with spectral responsivities that are close to the erythemal/carcinogenic action spectrum of skin have been installed at several centers of population in New Zealand, including Auckland, 37 degrees S, Wellington, 41 degrees S and Christchurch, 43.5 degrees S. The data set covers the period from the time the radiometry program commenced in 1988/1989 to the end of the southern summer, March 1995. The radiometers were recalibrated annually and the data were corrected for changes in the absolute responsivity of the radiometers. Erythemally effective UV irradiances at solar zenith angles of 30 degrees and 45 degrees were then extracted from the data set. No monotonic trend in these data is apparent, although there are statistically significant differences in mean irradiances from one year to the next. An example of this is the decrease observed in all sites following the Mt. Pinatubo eruption in June 1991. The maximum erythemally effective insolations at solar zenith angles of 30 degrees and 45 degrees were consistently lower in Christchurch than in the other two New Zealand sites. This could arise from higher levels of atmospheric turbidity and/or tropospheric ozone at this location. Also, a seasonal increase in erythemally effective UV insolation from spring to autumn was observed each year in all three New Zealand sites.

Zygomycosis (mucormycosis) and HIV infection: report of three cases and review

We report three cases of zygomycosis (mucormycosis) occurring in three individuals infected with the human immunodeficiency virus (HIV) and review 12 other published cases. We present the only two case reports of disseminated zygomycosis in AIDS patients, and the only AIDS patient with renal zygomycosis to survive without nephrectomy, receiving intravenous (i.v.) amphotericin alone. Coinfection with zygomycosis and HIV is rare, occurs primarily in patients with low CD4+ lymphocyte counts, does not always require the usual predisposing conditions for zygomycosis, and may be the presenting opportunistic infection among HIV-infected persons. Transient episodes of neutropenia occurring within 4 months before presentation may be a risk factor for this disease. Zygomycosis may arise in multiple sites including the basal ganglia, cutaneous tissue, kidney, respiratory tract, and may be disseminated. Occurring more commonly in, but not restricted to, injection drug users, it is significantly associated with sites other than basal ganglia in those patients with advanced HIV disease or AIDS. The presenting symptoms are related to the site of involvement, and the illness may develop insidiously or progress rapidly to a fulminant course. Successful therapy usually consists of surgical debridement and intravenous amphotericin B. Overall mortality in this review is 40%, and is significantly associated with sites of disease inaccessible to surgical debridement.

Detection of candidates for cancer cell motility inhibitory protein in the Dunning adenocarcinoma model

The more differentiated components of a primary tumor may produce substances that reduce the growth rate and metastatic potential of more aggressive components. In the Dunning R-3327 prostatic adenocarcinoma model, cancer cell motility is required for metastatic potential. Medium conditioned by the non-motile, non-metastatic G subline contains proteins of molecular weight 50-100 kDa that inhibited the motility of the highly motile, highly metastatic MAT-LyLu subline. G subline-conditioned medium was separated by DEAE-cellulose chromatography using a linear gradient of 0-0.5 M NaCl in 100 mM Tris at pH 8.3. The motility inhibitory activity of G-conditioned medium was localized to column fractions 51-70 that contained 18% of the applied protein and only 6.5% of the proteins secreted by the G cells. Analysis of pooled fractions 51-60 and 61-70 by two-dimensional gel electrophoresis identified five protein families, with a total of 12 charged proteins of molecular weights approximating 66, 54, 50, 41 and 34 kDa, that were not present or present in reduced quantities in column fractions that did not inhibit motility. Isolation and identification of motility inhibitory protein may prove it the first substance discovered that is produced by a more differentiated component of a neoplasm that directly inhibits a metastasis-associated property.

Psychological profile of patients suffering from Crohn's disease and ulcerative colitis

Patients with Crohn's disease (CD, n = 61) and ulcerative colitis (UC, n = 24) were studied using an interview and a series of percept-genetic tests describing anxiety, defensive strategies, and the self-image. Attention was specifically directed at a subgroup of CD (n = 15) with its inflammation limited to the colon (colon Crohn, CC). There was also a control group (n = 43). CC had more immature parent relations than the other groups. They were more childishly concrete and more alexithymic. While CC differ from other Crohn patients in many respects, the real cleft opens up with regard to UC, in spite of location of their illness. CC patients obviously have a psychological profile of their own.

Suppression of the tumorigenic phenotype of a rat liver epithelial tumor cell line by the p11.2-p12 region of human chromosome 11

Comparative chromosomal mapping studies and investigations of tumor-associated chromosomal abnormalities suggest that the development of hepatic tumors in humans and rats may share a common molecular mechanism that involves inactivation of the same tumor suppressor genes or common genetic loci. We investigated the potential of human chromosomes 2 and 11 to suppress the tumorigenic phenotype of rat liver epithelial tumor cell lines. These tumor cell lines (GN6TF and GP7TB) display elevated saturation densities in culture, efficiently form colonies in soft agar, and produce subcutaneous tumors in 100% of syngeneic rat hosts with short latency periods. Introduction of human chromosome 11 by microcell fusion markedly altered the tumorigenicity and the transformed phenotype of GN6TF cells. In contrast, the tumorigenic potential and phenotype of GP7TB cells was unaffected by the introduction of human chromosome 11, indicating that not all rat liver tumor cell lines can be suppressed by loci carried on this chromosome. Introduction of human chromosome 2 had little or no effect on the tumorigenicity or cellular phenotype of either tumor cell line, suggesting the involvement of chromosome 11-specific loci in the suppression of the GN6TF tumor cell line. The GN6TF-11neo microcell hybrid cell lines displayed significantly reduced saturation densities in monolayer cultures, and their ability to grow in soft agar was completely inhibited. Although GN6TF-11neo cells ultimately formed tumors in 80-100% of syngeneic rat hosts, the latency period for tumor formation was much longer. Molecular characterization of GN6TF-11neo microcell hybrid cell lines indicated that some of the clonal lines had spontaneously lost significant portions of the introduced human chromosome, partially delineating the chromosomal location of the putative tumor suppressor locus to the region between the centromere and 11p12. Molecular examination of microcell hybrid-derived tumor cell lines further defined the minimal portion of human chromosome 11 capable of tumor suppression in this model system to the region 11p11.2-p12.

Diffuse panbronchiolitis in a Hispanic man with travel history to Japan

Diffuse panbronchiolitis is a chronic airflow disorder of obscure origin, which has been reported infrequently outside of Japan and never with any long-term follow-up. We report such a case in a Hispanic man. Furthermore, this patient had an extensive travel history to the Far East, including Japan. This case raises the possibility of a poorly transmissible infectious agent responsible for the disease.

Differential dependence of the tumorigenicity of chemically transformed rat liver epithelial cells on autocrine production of transforming growth factor alpha

The tumorigenic phenotype in rat liver epithelial cells overexpressing c-myc may depend on a transforming growth factor (TGF)-alpha/epidermal growth factor receptor autocrine loop (L. W. Lee et al., Cancer Res., 51: 5238-5244, 1991). In the present study, we have used constitutive sense and antisense TGF-alpha expression vectors to modify TGF-alpha production in carcinogen-transformed clonal derivatives of a rat liver epithelial cell line, WB-F344, that variably express c-myc, endogenous TGF-alpha, and tumorigenicity. Transgene-mediated TGF-alpha protein production was elevated 2- to 9-fold in derivatives of a low c-myc-expressing transformed cell line, GN4, and 35-fold in a derivative of a high c-myc-expressing cell line, GN6. Although the GN4- and GN6-derived cell lines expressed functional EGF receptor and steady-state c-myc mRNA levels that were comparable to their respective parental cell lines, increased TGF-alpha expression did not increase the tumorigenicity of the derivatives relative to the parental cell lines. Similarly, in vitro growth characteristics of the GN4- and GN6-derived cell lines were not markedly altered by increased autocrine TGF-alpha production. Additionally, GN4, GN6, and their derivatives were, for the most part, unresponsive to exogenously applied TGF-alpha in vitro. In contrast, antisense TGF-alpha RNA expression significantly suppressed endogenous TGF-alpha production in a high c-myc-expressing, high TGF-alpha-expressing, highly tumorigenic clonal line, GP9; this suppression resulted in lowered steady-state c-myc levels and attenuated in vitro growth. Antisense-mediated suppression of all of these in vitro phenotypes in GP9 was reversed by exogenous TGF-alpha. The latency of tumor formation by the antisense derivative of cell line GP9 was significantly lengthened (> 3-fold) relative to the time required for tumor formation by its parental cell line. These results demonstrate that a TGF-alpha/epidermal growth factor receptor autocrine loop may be necessary for exaggerated in vitro and in vivo growth of some transformed rat liver epithelial cells (e.g., GP9); however, the autocrine loop is not generally sufficient to support tumorigenicity, even in transformed clonal lines expressing elevated levels of c-myc.

Ketoconazole and sulphaphenazole as the respective selective inhibitors of P4503A and 2C9

1. The potential of ketoconazole and sulphaphenazole to inhibit specific P450 enzyme activities (1A2, 2A6, 2B6, 2C9/8, 2C19, 2D6, 2E1, 3A and 4A) was investigated using human liver microsomes. 2. Ketoconazole demonstrated an inhibitory effect on cyclosporine oxidase and testosterone 6 beta-hydroxylase activities, with mean IC50's of 0.19 and 0.22 microM respectively. Ketoconazole inhibition of the other P450 activities investigated was significantly less, as illustrated by IC50's of at least a magnitude higher. 3. Sulphaphenazole was shown to have an inhibitory effect on tolbutamide hydroxylase activity, with a mean IC50 of 0.8 microM in incubations containing 100 microM tolbutamide. Sulphaphenazole (at concentrations of up to 100 microM) did not exhibit any significant inhibition of the other enzyme activities investigated. 4. Ketoconazole and sulphaphenazole are the respective selective inhibitors of P4503A and 2C9. Ketoconazole at 1 microM and sulphaphenazole at 10 microM can be used to establish the involvement of P4503A and 2C9 respectively in oxidative reactions in human liver microsomes.

Novel electrophoretic protocol for collection of mutations in the lambda light chain immunoglobulin gene in a human B-lymphoblastoid cell strain

Spontaneous and chemically induced mutation was examined in the lambda light chain immunoglobulin gene in a human B-lymphoblastoid cell strain (T5-1). The hemizygous lambda gene is a unique mutational target gene which codes for a protein that is both expressed on the cell membrane and secreted. Mutations in the lambda gene were detected by analysis of western blots of isoelectric focusing gel electrophoresis of T5-1 cell conditioned culture medium. None of 5,841 individual clones established from vehicle-exposed populations had detectable variations in the isoelectric banding pattern of the constitutively secreted lambda immunoglobulin protein. In contrast, 113 of 6,128 clonal populations established from N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-exposed populations exhibited stable variations in expression of the lambda immunoglobulin: isoelectric variants (n = 3) and non-secretors (n = 110). MNNG-induced mutations in the lambda gene, which resulted in lambda immunoglobulin proteins with altered isoelectric points (pIs), occurred at a frequency of no less than 4.9 x 10(-4) mutations/cell, indicating the mature rearranged lambda immunoglobulin gene is comparably sensitive to carcinogen induced mutation as other human autosomal target genes. Approximately one-half of the MNNG-induced non-secretor mutant clones lacked lambda mRNA while one-half maintained constitutive transcription and expression of the lambda immunoglobulin on the cell surface, demonstrating that carcinogen damage interdicted gene function at multiple points.

Characterisation of the cytochrome P450 enzymes involved in the in vitro metabolism of granisetron

1. The metabolism of granisetron was investigated in human liver microsomes to identify the specific forms of cytochrome P450 responsible. 2. 7-hydroxy and 9'-desmethyl granisetron were identified as the major products of metabolism following incubation of granisetron with human liver microsomes. At low, clinically relevant, concentrations of granisetron the 7-hydroxy metabolite predominated. Rates of granisetron 7-hydroxylation varied over 100-fold in the human livers investigated. 3. Enzyme kinetics demonstrated the involvement of at least two enzymes contributing to the 7-hydroxylation of granisetron, one of which was a high affinity component with a Km of 4 microM. A single, low affinity, enzyme was responsible for the 9'-desmethylation of granisetron. 4. Granisetron caused no inhibition of any of the cytochrome P450 activities investigated (CYP1A2, CYP2A6, CYP2B6, CYP2C9/8, CYP2C19, CYP2D6, CYP2E1 and CYP3A), at concentrations up to 250 microM. 5. Studies using chemical inhibitors selective for individual P450 enzymes indicated the involvement of cytochrome P450 3A (CYP3A), both pathways of granisetron metabolism being very sensitive to ketoconazole inhibition. Correlation data were consistent with the role of CYP3A3/4 in granisetron 9'-desmethylation but indicated that a different enzyme was involved in the 7-hydroxylation.

Development of dexamethasone-inducible tyrosine aminotransferase activity in WB-F344 rat liver epithelial stemlike cells cultured in the presence of sodium butyrate

Sodium butyrate acts as a differentiation-promoting agent for a wide variety of cell types, including some tumor cell lines. In this study, we examined the effects of sodium butyrate (SB) on the functional differentiation of cultured WB-F344 rat liver epithelial stemlike cells. Treatment of WB-F344 cells with 3.75 mM SB resulted in an inhibition of cellular proliferation, alterations to normal cellular morphology (increased cell size and decreased nuclear/cytoplasmic ratio), and significant increases in cellular protein synthesis. The SB-mediated changes in cell morphology, proliferative status, and protein catabolism were accompanied by development of dexamethasone-inducible tyrosine aminotransferase (TAT) enzyme activity. Culture of WB-F344 cells in growth medium containing SB and dexamethasone (DEX; 1 x 10(-6) M) resulted in greater than sevenfold increase in the basal TAT activity compared with control cultures. An additional sixfold increase in TAT activity was observed when cells cultured in medium containing SB and DEX were exposed to 1 x 10(-7) M DEX during the last 24 hours of culture. The DEX-inducible TAT activity developed by SB-treated WB-F344 cells responded to the modulating effects of insulin and L-tyrosine in a manner that closely resembled that reported for cultured hepatocytes and hepatoma cell lines. These studies show that treatment of WB-F344 rat liver epithelial stemlike cells with the differentiation-promoting agent SB in vitro leads to expression of the differentiation-specific hepatocyte enzyme TAT.

Age-dependent regulation of the tumorigenic potential of neoplastically transformed rat liver epithelial cells by the liver microenvironment

Neoplastically transformed rat liver epithelial cell lines (GN6TF and GP7TB), which form tumors with short latency at s.c. or i.p. transplantation sites of syngeneic rats, did not form tumors or were weakly tumorigenic following transplantation into the livers of young adult rats and expressed increasing tumorigenicity in livers of increasingly aged rats. These results suggest that progressive alterations in the hepatic parenchyma with increasing age enabled tumor formation by providing a less suppressive microenvironment for expression of the tumorigenic phenotype. Age is widely recognized as a significant risk factor in the development of neoplasia; this study describes a model for investigation of the influence of age-dependent changes in the hepatic microenvironment on the development of hepatic cancer.

Inhalation risk in low-gravity spacecraft

Inhalation risks on long-duration manned spaced flight include gasses chronically released by outgassing of materials, gasses released during spills, thermodegradation events (including fires) with their attendant particulates, and fire extinguishment. As an example, an event in which electronic insulation consisting of polytetrafluoroethylene undergoes thermodegradation on the Space Station Freedom was modeled experimentally and theoretically from the initial chemistry and convective transport through pulmonary deposition in humans. The low-gravity environment was found to impact various stages of event simulation. Critical unknowns were identified, and these include the extent of production of ultrafine particles and polymeric products at the source in low gravity, the transport of ultrafine particles in the spacecraft air quality control system, and the biological response of the lung, including alveolar macrophages, to this inhalation risk in low gravity.

Overexpression of c-K-ras, c-N-ras and transforming growth factor beta co-segregate with tumorigenicity in morphologically transformed C3H 10T1/2 cell lines

Morphologic transformation and tumorigenicity are separate cellular phenotypes in transformed 10T1/2 cells. We have investigated the levels of expression of genes for c-myc, c-H-ras, c-K-ras, c-N-ras, TGF beta and Rb in 42 morphologically transformed 10T1/2 cell lines, in an attempt to define the molecular mechanisms governing morphologic transformation and tumorigenicity in the 10T1/2 cell system. The 10T1/2 cell lines investigated generally overexpressed mRNAs for c-myc, c-H-ras, and TGF beta relative to the levels expressed by wild-type 10T1/2 cells (levels of expression > 1.5-fold that of wild-type 10T1/2 cells). In contrast, only half of these cell lines overexpressed mRNAs for c-N-ras and/or Rb relative to wild-type 10T1/2 cells, and only 25% overexpressed c-K-ras mRNA. The mean levels of mRNA expression for each of c-K-ras, c-N-ras and TGF beta genes in tumorigenic cell lines were significantly greater than the mean levels of expression in non-tumorigenic cell lines, suggesting an association between tumorigenicity and the levels of expression of these specific genes. In contrast, levels of expression for c-myc, c-H-ras and Rb genes were not correlated with tumorigenicity. Cell lines that coexpressed high levels of c-K-ras, c-N-ras and TGF beta genes were likely to be tumorigenic (11/12 cell lines were tumorigenic), whereas cell lines that coexpressed low levels of these genes were unlikely to be tumorigenic (1/10 cell lines were tumorigenic). High expression of TGF beta was sufficient for tumorigenicity in the absence of high levels of expression of c-K-ras and c-N-ras (5/5 cell lines were tumorigenic). Elevated expression of either c-K-ras or c-N-ras alone was insufficient for tumorigenicity, however, coordinate overexpression of both c-K-ras and c-N-ras was associated with tumorigenicity irrespective of the expression status for TGF beta (13/15 cell lines were tumorigenic). These results suggest that overexpression of c-myc, c-H-ras and TGF beta are commonly associated with, and possibly mechanistically related to, the process of morphologic transformation in 10T1/2 cells. In addition, these results suggest that progression from morphologic transformation to tumorigenicity in 10T1/2 cell lines is frequently accompanied by overexpression of c-K-ras and c-N-ras, and by enhancement of the level of overexpression of TGF beta.

DNA contents and chromosomes of clonal lines of transformed rat liver epithelial cells and of cells from their derived tumors

Clonal lines of transformed rat liver epithelial cells, derived from a single population of cloned diploid rat liver epithelial (stem-like) cell line (WB-F344) by exposure in vitro to N-methyl-N'-nitro-N- nitrosoguanidine (MNNG), produce hepatocellular carcinomas, hepatoblastomas and adenocarcinomas in syngeneic rats (Tsao and Grisham, Am. J. Pathol., 127, 168-181, 1987). In this study we show that these clonal lines demonstrate near-diploid (GN clones) or near-triploid (GP clones) aneuploidy and the universal occurrence of non-random chromosomal abnormalities. Marker chromosomes that involved four autosomes--a non-reciprocal translocation involving chromosomes 1 and 7 (t1q43;7q34), and addition of DNA of unknown origin to the pericentromeric regions of chromosomes 4 and 10--occurred in all of the cells of all transformed clones and in the cells of tumors that grew from them. New marker chromosomes involving the same regions of chromosomes 4 and 7 were found in several cell lines established from independent tumors. The preservation of marker chromosomes in tumor cells in the face of random loss and gain of other chromosomes suggests that these non-random aberrations were necessary for tumor formation. The presence of marker chromosomes was associated with increased expression of the c-myc gene (located at q34 on chromosome 7), the c-H-ras gene (located at q41-43 on chromosome 1) and the c-K-ras and TGF alpha genes (both located at unknown sites on chromosome 4), which we have previously shown to be highly correlated with tumorigenicity in these same transformed clonal lines (Lee et al., Cancer Res., 51, 5238-5244, 1992).

Short-term diethylnitrosamine-induced oval cell responses in three strains of mice

The oval cells of the liver have been identified as target cells of chemical carcinogens during rat hepatocarcinogenesis and are believed to act as liver stem cells. In this study mice (strains C3H/EJ (C3H), C57/BL6J (C57) and hybrid B6C3F1 (F1)) were sacrificed at 1, 3 and 7 days after administration of a single dose of the carcinogen diethylnitrosamine (DEN), and histopathological studies of oval cells were evaluated using Haematoxylin and Eosin (H&E), Picro-Mallory (P-M), alpha-fetoprotein (A-FP) and glutathione S-transferase placental form (GST-pi) staining techniques and electron microscopy (EM). Increased oval cell proliferation was observed as soon as one day following exposure of the mice to DEN, in a manner consistent with C3H and C57 mice exhibiting high and low susceptibility to DEN respectively, with hybrid F1 mice being intermediate in DEN sensitivity. This analysis indicates that, in mice, oval cells are target cells at very early stages of liver carcinogenesis and supports the notion that oval cells are potential liver stem cells.

HIV and pulmonary hypertension: a review

We describe two unique cases of pulmonary hypertension in association with the human immunodeficiency virus (HIV) and review the 28 previously reported cases in the world literature. Our first patient has coexistent chronic active hepatitis, which has previously been associated with the development of plexogenic pulmonary hypertension; however, our second case clearly demonstrates a closer link between HIV infection and pulmonary hypertension. Unlike previously reported cases, our latter case was devoid of all other coexistent factors including intravenous drug abuse, hepatitis B antigenemia, coexisting immunologic lung parenchymal injury, and hepatitis. Additionally, this is the first case documenting the presence of asymptomatic type II cryoglobulins in an HIV-positive patient with plexogenic pulmonary hypertension.

Morphologic transformation of the C3H 10T1/2 cell line is accompanied by altered expression of the p53 tumor suppressor gene

Wildtype 10T1/2 cells and 42 clonally derived morphologically transformed 10T1/2 cell lines were evaluated for expression of p53 mRNA and protein. Wildtype 10T1/2 cells expressed detectable levels of p53 mRNA and multiple immunologically distinct forms of the p53 protein, including both PAb240- and PAb246-reactive conformations of the protein. However, DNA sequence analysis revealed no mutations within the coding sequence of the expressed p53 gene(s) in wildtype 10T1/2 cells. Morphologic transformation of 10T1/2 cells resulted in clonal cell lines that overexpressed p53 mRNA and total p53 protein (PAb421-reactive) relative to the level of expression in wildtype 10T1/2 cells. Immunoprecipitation analysis demonstrated the expression of both PAb246-reactive and PAb240-reactive conformations of the p53 protein in all morphologically transformed 10T1/2 cell lines evaluated, irrespective of the tumorigenic potential of the individual line. Nonetheless, expression of PAb240-reactive p53 protein at levels equal to or higher than that found in wildtype 10T1/2 cells was associated with tumorigenicity in morphologically transformed 10T1/2 cell lines, suggesting that the relative contribution of PAb240-reactive p53 protein to the total cellular p53 protein represents an important determinant for the expression of the tumorigenic phenotype. Our results demonstrate that altered expression of p53 represents a common feature of morphologically transformed 10T1/2 cell line, suggesting that alteration of the expression of the p53 tumor suppressor gene may represent an early and necessary step in the morphologic transformation of 10T1/2 cells. Additionally, overexpression of PAb240-reactive p53 protein may influence the tumorigenic potential of morphologically transformed 10T1/2 cell lines.