Both products of the fosB gene, FosB and its short form, FosB/SF, are transcriptional activators in fibroblasts.

We demonstrate that a member of the fos family, the fosB gene, gives rise to two transcripts by alternative splicing of exon 4, generating two proteins, FosB of 338 amino acids and a short form, FosB/SF, which contains the DNA binding and dimerization domains but not the 101 amino acids of the C terminus. FosB/SF activates an AP-1-chloramphenicol acetyltransferase construct in NIH 3T3 cells, as determined by transient and stable transfections, although more weakly than does FosB. In contrast to FosB, FosB/SF has lost its ability to repress the dyad symmetry element of the c-fos gene. FosB/SF when expressed in excess to FosB can downmodulate the activity of FosB. Constitutive expression of high levels of FosB/SF in NIH 3T3 cells has no significant inhibitory effect in the induction of cell proliferation or cell cycle progression, indicating that FosB/SF is not a negative regulator of cell growth. This conclusion is further confirmed by the observation that the majority of the Jun molecules are complexed with FosB/SF in the FosB/SF-overexpressing cells.

Relationships of the structure and function of the interferon receptor to hormone receptors and establishment of the antiviral state.

This report describes similarities between the structure and function of the interferon receptor and receptors for glycoprotein hormones and several bacterial toxins. Specifically, it describes several common molecular and mechanistic elements, including: (a) the presence of a glycoprotein as well as a ganglioside component in the receptor; (b) changes in membrane structure as a consequence of interferon action; (c) interferon-induced intracellular cyclic adenosine 3':5'-monophosphate changes; and (d) alterations in the flux of certain ions across the membrane. Since interferon has an antiviral effect, these results define a relationship between hormonal perturbation of cellular events and the ability of an agent to prevent or suppress viral infections of cells. Further definition of these relationships should be important to our understanding of the oncogenic state, of hormonal effects on the oncogenic state, and of other human diseases in which hormonal perturbations of non-target tissues or cross-reactivity of receptors could be pathogenic.

Regulation by calcium and calmodulin of adenylate cyclase from rabbit intestinal epithelium.

The effect of calcium on adenylate cyclase from rabbit small intestine has been studied using a particulate preparation obtained from isolated epithelial cells. Both basal and vasoactive intestinal peptide-stimulated activities were inhibited by calcium concentrations in the micromolar range. In the presence of calmodulin, a biphasic response was obtained. At low calcium concentration (4 X 10(-9)-6 X 10(-8) M) the enzyme was activated up to 50%. As the Ca2+ concentration was increased, the enzyme was concomitantly inhibited. Half-maximal inhibition of calmodulin-dependent activity was obtained at 1 microM free Ca2+. The activation of the enzyme was also dependent on the concentration of Mg2+. At less than 1 microM Ca2+, the enzyme exhibited a biphasic response, being activated at below 3 mM Mg2+ and inhibited at higher concentrations. At Ca2+ concentrations that were inhibitory, the enzyme did not show the biphasic response to Mg2+. At concentrations above 3 mM, the maximal rate (Vmax) remained constant. Vmax was inversely proportional to the concentration of Ca2+ present. Calmodulin altered Vmax when acting on vasoactive intestinal peptide-stimulated enzyme. Calmodulin had no effect on the Km for hormone activation. The calmodulin-dependent activity was inhibited by incubation with trifluoperazine.

Permeability properties of isolated enterocytes from rat small intestine.

Metabolic and permeability properties of enterocytes isolated by treatment of rat small intestine with hyaluronidase or EDTA were compared. No significant difference was observed in the ability of the two types of cell to produce lactate from glucose. However, while cells obtained with hyaluronidase accumulate alpha-methylglucoside, cells obtained with EDTA were unable to accumulate the sugar above the medium concentrations. When resuspended in a medium designed to resemble the intracellular medium, potentiometric measurements showed that cells obtained with hyaluronidase released Ca2+ to the medium while cells obtained with EDTA accumulated it. Using 45Ca transport assays, this was shown to be an ATP-dependent process, the accumulated 45Ca being totally released by the addition of the ionophore A23187. When cells obtained with EDTA were resuspended in a medium containing concentrations of free Ca2+ higher that 10 microM, the uptake was partially inhibited by sodium orthovanadate and also by oligomycin and antimycin. At free Ca2+ concentrations lower than 1 microM, the accumulation was inhibited up to 87% by sodium orthovanadate while mitochondrial inhibitors inhibited only 5%. Thus, it appears that during their preparation cells obtained with hyaluronidase retain their integrity while cells obtained with EDTA become permeable to Ca2+ and other ions. The usefulness of both types of preparation in metabolic and transport studies is discussed.

The specificity of induction of alpha-galactosidase from Saccharomyces carlsbergensis.

A number of sugars and derivatives have been tested for their ability to induce the synthesis of alpha-galactosidase from Saccharomyces carlsbergensis. Besides galactose and the substrates of the enzyme melibiose, raffinose and stachyose, D-galacturonic acid, L-arabinose, D-tagatose, methyl-alpha-D-galactoside, lactose and isopropyl-beta-D-thiogalactoside were able to act as inducers. Of these, methyl-alpha-D-galactoside, lactose, isopropyl-beta-D-thiogalactoside and L-arabinose have been shown to be gratuitous inducers with which kinetic studies of induction have been carried out. Lactose was the most efficient inducer, giving a maximal differential rate of synthesis of the enzyme of 110 mU/10(7) cells at a concentration of 180 mM, followed by L-arabinose (60 mU/10(7) cells at 40 mM), isopropyl-beta-D-thiogalactoside (43 mU/10(7) cells at 60 mM) and methyl-alpha-D-galactoside (25 mU/10(7) cells at 150 mM). The concentration of inducer required to obtain half-maximal induction was similar for lactose, L-arabinose and isopropyl-beta-D-thiogalactoside and about 5-fold higher for methyl-alpha-D-galactoside. The property of the compounds to act as inducers was compared to their ability to interact with the enzyme and the results discussed in terms of the molecular structures which are recognized by the enzyme and by the induction machinery.

Cholera toxin induces changes in the ion permeability of intestinal brush border membranes.

Cholera toxin can alter the ion permeability of brush border membrane vesicles from rabbit small intestine. This alteration is reflected by differences in membrane potential-stimulated, Na-dependent, D-[3H]glucose transport by these vesicles, as well as by an enhancement in the accumulation of the lipophilic cation [3H]tetraphenylphosphonium in response to an artificially imposed membrane potential. Analogous effects were observed when the intact tissue was treated with the toxin and the vesicles subsequently obtained. An important implication of this finding is that cholera toxin does not need to activate adenylate cyclase to induce permeability changes in the cell membrane since the experiments were carried out in conditions where neither ATP nor cyclic AMP was present.

Glucose activation of adenylate cyclase in Saccharomyces cerevisiae mutants lacking glucose-phosphorylating enzymes.

The "in vitro" activation by glucose of the RAS-adenylate cyclase system in membranes from a strain of Saccharomyces cerevisiae lacking any functional glucose kinase activity presents similar features to those of the wild type. However, this triple mutant appears to be unable to produce the glucose-induced increase of cAMP levels "in vivo". The results obtained in vitro indicate that the signal transduction mechanism is active in the mutant cells and suggest that the absence of intracellular acidification in vivo might be responsible for the lack of response to glucose.

EMS1 gene amplification correlates with poor prognosis in squamous cell carcinomas of the head and neck.

The relationship between CCND1 and/or EMS1 amplification and disease outcome was studied in a prospective series of 104 head and neck squamous cell carcinomas treated by surgical resection. The CCND1 and EMS1 copy number in tumor samples was estimated by differential PCR. The presence or absence of amplification was analyzed in relation to clinicopathological variables, tumor recurrence, and patient survival. CCND1 amplification occurred in 32 cases (31%) and was associated with increased lymph node stage (P = 0.005) and advanced disease stage (P = 0.003). EMS1 amplification was identified in 21 cases (20%) and was related with advanced T stages (P = 0.001), increased lymph node stage (P = 0.02), advanced disease stage (P = 0.041), poor histological differentiation (P = 0.018), recurrent disease (P = 0.0004), and reduced disease-specific survival (P < 0.0001). Coamplification of both genes occurred in 11 cases (11.5%). Multivariate analysis confirmed that in addition to regional lymph node status, EMS1 amplification is an independent predictor of death from the tumor (P = 0.0027). CCND1 amplification was not prognostic. These data indicate that EMS1 amplification, but not CCND1 amplification, predicts early recurrence and reduced survival in squamous cell carcinoma of the head and neck. The prognostic significance previously attributed to CCND1 amplification may be attributable to its frequent coamplification with EMS1.

Activation of adenylate cyclase in cdc25 mutants of Saccharomyces cerevisiae.

The activation of adenylate cyclase by guanine nucleotides and 6-deoxyglucose was studied in membrane preparations from S. cerevisiae mutants lacking the CDC25 gene product. Adenylate cyclase from cdc25 ts membranes was activated by GTP and GppNHp in membranes from cells collected after glucose was exhausted from the medium. The activation was also observed in membranes from repressed cells at 2.5 mM Mg2+. It is also shown that 6-deoxyglucose can activate adenylate cyclase in the absence of CDC25 gene product. The relative amount of membrane-bound adenylate cyclase was drastically reduced in cdc25 ts membranes when subjected to the restrictive temperature, while no significant change was observed in the wild type. These data suggest that Cdc25 might not be required in certain conditions for the guanine nucleotide exchange reaction in Ras and that it might be implicated in anchoring the Ras/adenylate cyclase system to the plasma membrane.

Molecular cloning of a mouse homologue for the Drosophila splicing regulator Tra2.

We report the identification of a mouse cDNA, SIG41, encoding a protein of 288 amino acids that is 45% identical (58% similar) to the Drosophila splicing regulator Tra2. SIG41 cDNA contains four polyadenylation signals whose alternative use gives rise to four types of transcripts (2.1, 2.0, 1.5, and 1.4 kb) in mouse cells. Northern analysis and RT-PCR assays showed that SIG41 mRNA is present in virtually all the cell lines and tissues studied, with remarkable levels of expression in uterus and brain tissues. Differential stability of the SIG41 mRNAs was detected in mouse macrophage cells.

In vitro activation of the Saccharomyces cerevisiae Ras/adenylate cyclase system by glucose and some of its analogues.

Using crude membrane preparations of Saccharomyces cerevisiae, we have demonstrated that glucose and glucose analogues which are not efficiently phosphorylated activate the guanine nucleotide-dependent adenylate cyclase in vitro. The activation appears to be mediated by the Ras proteins. Moreover, data are presented indicating that glucose and its analogues activate adenylate cyclase by stimulating the exchange of guanine nucleotides at its regulatory component. Thus, it has been possible to show the action of a physiological effector on the nucleotide exchange reaction in a member of the ras superfamily.

Amplification of ERBB oncogenes in squamous cell carcinomas of the head and neck.

The activation of ERBB oncogenes has been described in various human tumours, including squamous cell carcinomas of the head and neck (SCCHN), and, in some of them, it has been correlated with a poor prognosis. Tissue samples from 59 patients with SCCHN were studied. After DNA extraction, the ERBB1, ERBB2 and ERBB3 copy number in tumour samples was estimated with the polymerase chain reaction (PCR) method. The PCR products were analysed by agarose gel electrophoresis and quantified by image analysis techniques. 9 (15%) cases presented with ERBB1 amplification, which was correlated with lymph node involvement (P = 0.04), poorly differentiated tumours (P = 0.03) and a hypopharyngeal primary site (P = 0.035). No correlation among amplification status, recurrence, metastases and survival was observed, although this may be due to the small number of patients in the amplified group. None of the 59 cases presented amplification of ERBB2 and ERBB3 oncogenes.

Measurement of cytotoxicity by propidium iodide staining of target cell DNA. Application to the quantification of murine TNF-alpha.

A rapid and sensitive method is described for the determination of murine tumor necrosis factor (TNF-alpha), which can be performed in microtiter plates using a fluorescence plate scanner. The method is based on the binding of propidium iodide (PI), a membrane-impermeant dye, to nucleic acids of WEHI 164 cells, whose plasma membrane permeable due to TNF-alpha-induced cell damage. The analytical range for the proposed method is 0.3-200 pg/ml of TNF-alpha after 5 h of incubation. The optimal number of target cells was found to be 4-5X10(4)/well. The variability obtained for the PI assay was 7.6%; lower than that obtained with a commonly employed method in which MTT is used to determine cell viability (11.3%). Thus, the PI assay appears to be a reliable and reproducible method for the determination of biologically active TNF-alpha. The assay can be performed in a few hours and has the advantage over the current MTT and 51Cr-released assays that kinetic studies of TNF-alpha toxicity are possible since it permits multiple, sequenced measurements of cell viability during the incubation of the sample. The method can also be used for the determination of human TNF-alpha.

Differential regulation of the murine ribosomal protein L26 gene in macrophage activation.

In mouse RAW 264.7 macrophages, the gene for ribosomal protein L26 is positively regulated by silica. In order to study L26 gene expression a near full-length cDNA for mouse L26 was isolated and characterized. Sequence analysis revealed that mouse L26 is a 145 amino acid protein highly homologous to other vertebrate L26 proteins. The treatment of RAW 264.7 cells with the inflammatory mediators LPS and IFN gamma induced the expression of L26 mRNA, but the patterns of expression obtained differed markedly from silica. On the contrary, TNF alpha acted as a down-regulator of L26 gene. Our results suggest that the synthesis of ribosomal components in response to macrophage activators is inducer-specific. Mouse genomic DNA analysis revealed the presence of multiple (10-12) sequences related to the L26 gene.

Variability of genetic alterations in different sites of head and neck cancer.

OBJECTIVE: Tumors arising from different sites of the head and neck area have different clinical behavior. However, most of the studies on genetic alterations in head and neck squamous cell carcinomas do not make a distinction between the sites within this area. The objective of this study is to compare the genetic alterations in three different sites of the head and neck (larynx, oropharynx, and hypopharynx). STUDY DESIGN: Prospective study. METHODS: Thirty-eight laryngeal, 29 oropharyngeal, and 37 hypopharyngeal carcinomas were studied. DNA from tumor and healthy tissue was evaluated for amplification of the oncogenes at 11q13 region (CCND1, FGF3, FGF4 and EMS1) and of the oncogenes MYC and ERBB1; for integration of the human papillomavirus (HPV) types 6b and 16; for loss of heterozygosity (LOH) at p53 and NAT2; and for the cellular DNA content. RESULTS: FGF3 and FGF4 showed a significantly higher frequency of amplification in hypopharyngeal tumors (P =.006 and P =.0002, respectively). CCND1 amplification had a nearly statistically significant (P =.072) higher frequency of amplification in hypopharyngeal tumors. Aneuploid tumors were found in a significantly lower proportion in the larynx (P =.03) compared with the other sites. For the other genetic alterations, no significant differences among the three sites were found. CONCLUSIONS: These results suggest that cancers originating from different sites in the head and neck may have different tumor biology. Therefore, they should be considered as different entities.

MYC amplification in squamous cell carcinomas of the head and neck.

OBJECTIVES: To establish the frequency of MYC amplification in squamous cell carcinoma (SCC) of the head and neck to evaluate its correlation with clinicopathologic variables that are used in clinical practice. DESIGN: Cohort analytic study. SETTING: University Hospital. PATIENTS: Fifty-nine consecutive patients with SCC of the head and neck. INTERVENTION: Oncologic surgery. MAIN OUTCOME MEASURES: The MYC copy number in tumor samples was estimated with the polymerase chain reaction. The presence or absence of amplification was correlated with the anatomic site, T stage, nodal involvement, pathologic grade, recurrence, distant metastases, and survival. RESULTS: Six SCC specimens (11%) showed MYC amplification. A highly statistical correlation between MYC amplification and T stage was noted (P < .005). Amplification was also significantly correlated with a hypopharyngeal primary site (P < .05). No correlation among amplification status, nodal involvement, pathologic grade, relapse, metastases, and survival was observed. CONCLUSIONS: Amplification of MYC is associated with advanced primary tumors, and it appears to be a late event in the tumorigenesis of SCCS of the head and neck. However, there is no correlation between MYC amplification and prognosis.

Relationship of human papillomavirus to ploidy in squamous cell carcinomas of the head and neck.

To establish the relationship between the presence of human papillomavirus (HPV) gene sequences and the development of genetic abnormalities, 31 squamous cell carcinomas of the head and neck were studied for the presence of HPV types 6b and 16 and the DNA content by flow cytometry. Eighteen (58%) cases were aneuploid. HPV DNA was present in seven (22.5%) tumors. Five of them were positive for the HPV type 6b and two for the HPV type 16. Aneuploidy was correlated with poorly differentiated tumors. No correlation was found between the presence of HPV, DNA content, or tumor differentiation. Consequently, the presence of HPV gene sequences does not seem to be related to a higher incidence of genetic abnormalities in squamous cell carcinomas of the head and neck.

[Analysis of rearrangements in the first exon of c-myc oncogene in squamous cell carcinoma of the head and neck]. / Análisis de reordenamientos en el primer exón del oncogén c-myc en carcinomas epidermoides de cabeza y cuello.

Activation of c-myc has been implicated in the origin of different human tumors, and can be produced by diverse mechanisms as amplifications or rearrangements. We examined 55 squamous cell carcinomas of the upper aerodigestive tract for rearrangements involving the first exon of c-myc, which plays a regulatory role in the c-myc expressión. Polymerase chain reaction (PCR) amplification of different fragments of c-myc exon 1 was performed using four oligonucleotide primers that correspond to consecutive sequences from the 5' end of the c-myc exon 1, combined with one oligonucleotide that corresponds to the 3' end. Amplified c-myc PCR products appear as single bands of 580, 495, 417 and 333 base pairs on the electrophoretic analysis. Only in one case a rearrangement involving the first exon of c-myc was found. We concluded that gene rearrangement is not a common mechanism of activation of c-myc in squamous cell carcinomas of the head and neck.

[The relation between human papilloma virus and cellular DNA content in epidermoid carcinoma of the head and neck]. / Relación entre el virus del papiloma humano y el contenido celular de ADN en los carcinomas epidermoides de cabeza y cuello.

The relation between the presence of gene sequences of human papilloma virus (HPV) and the development of abnormalities in cellular DNA content was analyzed in 31 squamous-cell carcinomas of the head and neck. The integration of HPV types 16 and 6b by PCR and DNA content was studied by flow cytometry in 31 specimens from patients with squamous-cell carcinoma of the head and neck. Eighteen (58%) cases were aneuploid. HPV DNA was present in seven tumors (22.5%), five of then HPV-6b and two of them HPV-16. Aneuploidy correlated with poorly differentiated tumors. No correlation was found between HPV integration and either cellular DNA content or the degree of histological tumor differentiation. Therefore, the presence of HPV gene sequences did not seem to be associated with a higher incidence of aneuploidy in squamous-cell carcinoma of the head and neck.

A role for dorsal and ventral hippocampus in response learning.

The hippocampus and the striatum have been traditionally considered as part of different and independent memory systems despite growing evidence supporting that both brain regions may even compete for behavioral control in particular learning tasks. In this regard, it has been reported that the hippocampus could be necessary for the use of idiothetic cues in several types of spatial learning tasks. Accordingly, the ventral striatum receives strong anatomical projections from the hippocampus, suggesting a participation of both regions in goal-directed behavior. Our work examined the role of the dorsal and ventral hippocampus on a response learning task. Cytochrome c oxidase (C.O.) quantitative histochemistry was used as an index of brain oxidative metabolism. In addition, determination of C.O. subunit I levels in the hippocampus by western blot analysis was performed to assess the contribution of this subunit to overall C.O. activity. Increased brain oxidative metabolism was found in most of the studied hippocampal subregions when experimental group was compared with a swim control group. However, no differences were found in the amount of C.O. subunit I expressed in the hippocampus by western blot analysis. Our results support that both the dorsal and ventral hippocampus are associated with the use of response strategies during response learning.