Constitutive expression of the neutral PR-5 (OLP, PR-5d) gene in roots and cultured cells of tobacco is mediated by ethylene-responsive cis-element AGCCGCC sequences

The constitutive accumulation of tobacco neutral PR-5 (osmotin-like protein; OLP, PR-5d) in roots and cultured cells was studied in transgenic tobacco plants harboring the OLP promoter::GUS gene. This construct showed strong β-glucuronidase expression in vascular tissues and cortex of roots as well as in cultured cells. Analysis using a mutated promoter showed that ethylene-responsive elements (AGCCGCC) were necessary for constitutive expression in roots and cultured cells. An electrophoretic mobility shift assay indicated that ERF3 (EREBP3), an ethylene-responsive-element-binding factor that was reported to be expressed in roots and in cultured cells as well as in ethephon-treated leaves, could bind to the AGCCGCC sequences of the OLP gene. These findings suggest that AGCCGCC sequences and ERFs mediate the constitutive expression of the OLP gene in roots and cultured cells of tobacco.

Selectins induced by interleukin-1beta on the human liver endothelial cells act as ligands for sialyl Lewis X-expressing human colon cancer cell metastasis

We have previously reported that colon cancer cells metastasized to the liver expressed an increased amount of sialyl Lewis X (SLeX) antigen compared to their corresponding primary lesions. It is now well known that SLeX antigen and sialyl Lewis A (SLeA) antigen are ligands for the selectins expressed on the endothelial cells. Therefore, it is assumed that SLeX-rich colon cancer cells could be easily adhered to the endothelial cells that express selectins. In this report we have tried to induce selectin expression on the human liver sinusoidal endothelial cells and have examined the adhesion of SLeX-high or -low expressing colon cancer cells to the interleukin-1beta (IL-1beta)-treated liver specimens using Stamper-Woodruff assay. These human colon cancer cells are termed KM12HX or KM12LX cells, respectively. A significantly increased number of KM12HX cells adhered to the IL-1beta-treated liver specimens compared to KM12LX cells. The adhesion of KM12HX cells was inhibited by the pretreatment of tumor cells with anti-SLeX antibody or by the pretreatment of liver specimens with anti-selectin antibodies. Selectin expression on the liver sinusoidal endothelial cells and endothelial cells of blood vessels after IL-1beta treatment was confirmed by immunohistochemically using anti-selectin monoclonal antibodies (MAbs). These findings strongly suggest that SLeX-expressing cancer cells could adhere to the sinusoidal endothelial cells via an SLeX-selectin interaction system and this could be a first step for colon cancer cells that metastasize to the liver. The mechanism by which these selectins can be induced in vivo is the next problem to be considered.

Macroscopic distribution of coronary atherosclerotic lesions in cholesterol-fed rabbits

In the present study we macroscopically examined a change in the distribution of coronary atherosclerosis in cholesterol-fed rabbits. Rabbits were fed a cholesterol-enriched diet for 15 weeks, then replaced by a normal diet, and were sacrificed at 15, 24, 32 and 42 weeks after the start of the experiment. The coronary atherosclerosis in the cholesterol-fed rabbits was distributed more densely in the proximal portion than in the middle and distal portions, and the lesions were severe at 24 and 32 weeks after the start of the experiment. comparison of lesions in the three portions at these time points showed that the percentages of lesion areas in the proximal portion, the middle portion and the distal portion were approximately 51%, 21 to 25% and 0.2 to 3.7%, respectively. Macroscopic observation of the coronary atherosclerotic lesions showed that the lesions formed over the vessel lumen in the proximal portion within the range of approximately 5 mm from the orifice of the left coronary artery. In the middle portion, the lesions formed predominantly around the orifices of branches as small patchy lesions from 1 to 3 mm in diameter. These findings support previous histopathological reports that suggested that the incidence of stenosis in the proximal portion was high, and the incidence of lesion occurrence in the middle and the distal portions varied. The method, macroscopical investigation of the coronary artery, is useful for analyzing coronary atherosclerosis in the rabbit.

Structure of the human transcription factor TFIIF revealed by limited proteolysis with trypsin

In this study, the human general transcription factor IIF (TFIIF), a heteromeric complex of RAP74 and RAP30 subunits, was subjected to limited proteolysis with trypsin. The central region of RAP74 was demonstrated to be highly sensitive to trypsin while both the N- and C-terminal regions contained trypsin-resistant structures. In contrast, RAP30 digestion occurred after proteolysis of RAP74. The digestion pattern of RAP74 recruited into the preinitiation complex showed no marked difference from that of IIF, while RAP30 in the complex was protected from trypsin. These results indicate that RAP74 apparently contains three structural domains, the central one of which is externally surfaced and unstructured, but RAP30 is internally wrapped by RAP74. Furthermore, the accessibility of the central region of RAP74 is unaltered in the minimal preinitiation complex, while RAP30 is involved in promoter recognition through its DNA binding activity.

Characterization of a transferrin-independent iron uptake system in rat primary cultured cortical cells

Multiple transferrin-independent iron uptake (Tf-IU) systems are known to be involved in the internalization of free iron salt in various mammalian cells. However, the characteristics of a Tf-IU system in cortical cells are not clear. In this study, we characterized the Tf-IU systems in both cortical and glial predominant (GP) cells from rat cerebral cortex to investigate the mechanism by which iron (Fe) or aluminum (Al) accumulates in the cerebral cortex. The Tf-IU systems in both cells were temperature- and Ca2*-dependent. The upregulation of Tf-IU system in GP cells by Fe- or Al-nitrilotriacetate (Fe- or AI-NTA) was 2- or 4-fold higher than that of cortical cells. Chemiluminescence analysis specific for O2- and 1O2 also showed that the production of active oxygen species in Fe-loading GP cells was twice higher than that of Fe-loading cortical cells. These results suggest the existence of Tf-IU systems in both cortical and GP cells similar to those of HeLa cells whose Tf-IU is metal- and Ca-2+ dependent, and that the glial cells contribute to metal accumulation in cerebral cortex. The present study may help to explain the pathogenesis of neurodegenerative disorders caused by inducing oxidative stress.

Cloning and characterization of the Hakata antigen, a member of the ficolin/opsonin p35 lectin family

The Hakata antigen is a novel, thermolabile beta2-macroglycoprotein that reacts with sera from patients suffering from systemic lupus erythematosus. In this study we present the structure and the function of the Hakata antigen. We have identified cDNA clones encoding the Hakata antigen and analyzed its function. The cDNA included a possible open reading frame of 897 nucleotides, encoding 299 amino acids. The Hakata antigen consisted of a collagen-like domain in the middle section and a fibrinogen-like domain in the COOH terminus, both of which are homologous to human ficolin-1 and opsonin P35, indicating that these three molecules form a distinct family. The molecular mass of the Hakata antigen expressed in transfected cells was 35 kDa under reduced conditions, and it formed ladder bands under nonreducing conditions compatible with the previous result that the Hakata antigen exists in serum as homopolymers. Purified Hakata antigen sustained lectin activity, showing affinity with GalNAc, GlcNAc, D-fucose as mono/oligosaccharide, and lipopolysaccharides from Salmonella typhimurium and Salmonella minnesota. These results suggest that the Hakata antigen, a new member of the ficolin/opsonin P35 family, plays a role in the serum exerting lectin activity under physiological conditions.

[Chemotherapy of Hansen's disease in Japan--present status]

In order to know leprosy chemotherapy status in Japan, three recently conducted Government-supported nation-wide survey, namely chemotherapy research group survey (Takizawa, 1994, 71 cases) follow up result of Takizawa's study (Miyagi, 1997, 59 cases) and leprosy patient registry (Goto, 1996, 130 cases) were compared and analyzed. For most fresh and relapse cases, multi-drug therapy were applied, among them rifampicin/dapsone or rifampicin/dapsone/clofazimine combinations were selected in about half of new cases and about 1/3 of relapse cases. In many cases dose and intervals were based on WHO protocol, however smaller dosage was used in some cases. Quinolone (ofloxacin) was used in 40% of cases during the therapy. Reversal reaction was observed in 7/71 cases and erythema nodosum leprosum was observed in 6/71 cases. In order to prevent chemotherapy-induced deformities, we propose a modified protocol for new cases accompanied by reactional status, which starts with clofazimine monotherapy and followed by WHO/MB.

Interrelationship of cardiovascular effects, plasma levels of nicorandil, and vascular cGMP formation in conscious rats

The relationship between the dual activity of nicorandil (KATP channel-opening activity and nitrate-like action), plasma levels, and changes in vascular cGMP levels and cardiovascular parameters was investigated in conscious rats. Nicorandil (3 mg kg(-1), p.o.) was rapidly absorbed and caused a significant reduction in blood pressure, lasting for at least 1 h, increases in heart rate and femoral blood flow, and decreases in femoral vascular resistance. These were entirely abolished by intravenous glibenclamide (20 mg kg(-1)). The plasma concentration of nicorandil reached a maximum 30 min after dosing. After administration of nicorandil, a correlation was observed between blood pressure and plasma nicorandil level or femoral vascular resistance. A significant increase (P < 0.05) in the cGMP content of the thoracic aorta occurred 15 min after administration of nicorandil, and persisted for at least 2 h. These results imply that nicorandil induces vasodilatation by opening KATP channels in peripheral resistance vessels, leading to overt reduction of blood pressure, but acts on conductance vessels mainly through nitrate-like activity.

Vascular levels and cGMP-increasing effects of nicorandil administered orally to rats

We examined a relation between cyclic guanosine monophosphate (cGMP) production in thoracic aorta, as an indicator probably reflecting the vascular response, and the vascular as well as plasma levels of nicorandil administered orally to rats. Nicorandil (3 mg/kg) given orally was rapidly absorbed, reaching the maximal plasma (approximately 2,600 ng/ml) and vascular concentrations (approximately 176 ng/g) at 15 min after the dosing and thereafter decreased rapidly. Even 2 h after the dosing, the level of the vascular cGMP formation in vivo remained significantly higher (approximately 1,000 fmol/mg increase from the control level) in the nicorandil-treated group, compared with the vehicle-treated one, and was enough to develop pronounced muscle relaxation in in vitro aortic preparations. However, it seems that the vascular cGMP increase in vivo was not always correlated to the plasma concentration of nicorandil, because the plasma concentration (approximately 750 ng/ml corresponding to 3.5 microM) at 2 h after the dosing, caused only relatively low cGMP production (300-400 fmol/mg increase from the control level), when tested in in vitro aortic preparations. Our study may indicate, therefore, that the vascular cGMP elevation in vivo is due to the content of nicorandil effectively remaining at its vascular targets of action as well as the plasma nicorandil concentration.

Expression of proliferating cell nuclear antigen (PCNA) and apoptosis related antigen (LeY) in epithelial skin tumors

We semiquantitatively analyzed expression of PCNA and LeY in seborrheic keratosis (SK), actinic keratosis (AK), Bowen's disease (BD), and squamous cell carcinoma (SCC), using immunocytochemically stained tissue sections. PCNA expression increased in a stepwise fashion from low levels in normal skin to higher expressions within SK, AK, BD, and SCC. The levels of LeY protein also increased in this order. The PCNA expression pattern shifted from expression limited to the basal and suprabasal cell layers (in normal skin and SK) to expression extending to the upper squamous and granular layers (in AK, BD, and SCC). On the other hand, the pattern of LeY expression shifted from the granular (in normal skin) to the upper squamous (in SK and AK) and suprabasal layers (in BD and SCC). These findings suggest that PCNA expression is related to the degree of cell proliferation and that LeY expression is related to the degree of differentiation or keratinization of tumor cells. In addition, PCNA and LeY show a reciprocal relationship in their expression.

Activation of mitogen-activated protein kinases is not required for the extension of neurites from PC12D cells triggered by nerve growth factor

Numerous studies with PC12 cells have suggested that the mitogen-activated protein (MAP) kinase pathway might play a major role in the neuronal differentiation that is induced by nerve growth factor (NGF). Cells of the PC12D subline extend neurites within several hours in response to NGF in the presence of inhibitors of the synthesis of RNA and protein. We examined the effects of a specific inhibitor 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059) of the MAP kinase kinase (MEK)/MAP kinase pathway on the NGF-induced outgrowth of neurites in PC12D cells. The increase in MAP kinase activity in response to NGF was reduced by 80% upon treatment of PC12D cells with 50 microM PD98059, whereas the NGF-dependent formation of ruffles and the subsequent outgrowth of neurites were not blocked by PD98059 at this concentration. The outgrowth of neurites from conventional PC12 cells by NGF was suppressed by the addition of 50 microM PD98059 as reported by Pang et al. [L. Pang, T. Sawada, J. Stuart,S.J. Decker, A.R. Saltiel, Inhibition of MAP kinase kinase blocks the differentiation of PC12 cells induced by nerve growth factor, J. Biol. Chem. 270 (1995) 13585-13588]. In contrast, the rapid regeneration of neurites from PC12 cells primed with NGF, was not altered in the presence of the same dose of the inhibitor of MEK. It appeared, therefore, that the activation of the MAP kinase pathway was not necessarily required for the NGF-dependent extension of neurites. When PC12D cells were transfected with the dominant inhibitory Ha-ras Asn-17 gene, the induction of the mutant Ras protein led the suppression of the rapid outgrowth of neurites in response to NGF but not to dibutyryl cyclic AMP (dbcAMP). The result implies a direct involvement of Ras protein in the NGF-induced signal transduction that lead to the formation of neurites in PC12D cells. We can conclude that the activation of MAP kinase and selective gene expression are required for the differentiation of conventional PC12 cells to sympathetic neuron-like cells and that activation of Ras protein and, subsequently, of a MAP kinase-independent pathway might be involved in the extension of neurites from PC12D cells or in the regeneration of neurites from primed PC12 cells in response to NGF.

The guinea-pig skin sensitization test revisited: an evaluation formula to predict possible sensitization levels for eight chemicals used in household products

In predicting human skin sensitization due to possible risky chemicals, it is not sufficient to evaluate solely the minimum induction dose (MID) or the standard challenge dose (SCD) in the Guinea Pig Maximization Test (GPMT). Nakamura et al. (1994) (Nakamura, A., Momma, J., Sekiguchi, H., Noda, T., Yamano, T., Kaniwa, M., Kojima, S., Tsuda, M., Kurokawa, Y., 1994. A new protocol and criteria for quantitative determination of sensitization potencies of chemicals by guinea pig maximization test. Contact Dermatitis 31, 72-85) previously measured the residual dose of chemicals in the products implicated in human allergic accidents, and stated that '... the level of chemical in the products (direct exposure-dose = DED) was similar to or higher than value of sensitization potency.' However, several of the chemicals listed in their article, show an even lower value of sensitization potency than the DED, although a potential correlation between results of the GPMT and the DED was seemed to be evident; a key question about the essential rule of those parameters therefore remains open. Using the data of Nakamura et al. (1994), we analyzed the functional rules of the three independent parameters, the MID, the SCD, and the DED on which the GPMT is based. Calculations of the degree of allergic reactions elicited in humans provided a range of discrimination constants (D) using the formula; D = DED/(MID*SCD). Possible human allergic accidents may be predicted when the dose of a candidate chemical in a chemical product (equal to DED) exceeds the value; D*(MID*SCD), following the correct evaluation of the MID as well as the SCD.

Ultrastructural changes in motor endplates of the lumbrical muscles of rats induced by a microsomal Ca2+ ATPase inhibitor, 2,5-di(tert-butyl)-1,4-hydroquinone

Female Wistar rats were treated orally for 5 days with 80 mg/kg body weight of 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ), a microsomal Ca2+ ATPase inhibitor. Motor endplates of the lumbrical muscles were examined by light and electron microscopy. There was a decrease in body weight in the treated rats from the first day after administration, and toxic signs appeared after the third day, such as adoption of a prone position, salivation, lacrymation, and an abnormal gait and/or muscle weakness. No remarkable macroscopic or light microscopic changes were noted in the lumbrical muscles as well as other peripheral nerves of hind legs of the treated rats killed 1 day after the last DTBHQ treatment. Ultrastructurally, neurotoxicity characterized by loss of synaptic vesicles and mitochondria in the motor endplates, and by destruction of the motor terminals was detected in the lumbrical muscles of the treated rats. These results strongly indicate that DTBHQ targets the motor endplates in the rat lumbrical muscles and suggest that the resultant damage is responsible for the appearance of neurological signs, such as an abnormal gait and loss of muscle control.

The PC motif: a novel and evolutionarily conserved sequence involved in interaction between p40phox and p67phox, SH3 domain-containing cytosolic factors of the phagocyte NADPH oxidase

The superoxide-generating NADPH oxidase, dormant in resting phagocytes, is activated during phagocytosis following assembly of the membrane-integrated protein cytochrome b558 and cytosolic factors. Among the latter are the three proteins containing Src homology 3 (SH3) domains, p67phox, p47phox and p40phox. While the first two factors are indispensable for the activity, p40phox is tightly associated with p67phox in resting cells and is suggested to have some modulatory role. Here we describe a systematic analysis of the interaction between p40phox and p67phox using the yeast two-hybrid system and in vitro binding assays with recombinant proteins. Both methods unequivocally showed that the minimum requirements for stable interaction are the C-terminal region of p40phox and the region between the two SH3 domains of p67phox. This interaction is maintained even in the presence of anionic amphiphiles used for the activation of the NADPH oxidase, raising a possibility that it mediates constitutive association of the two factors in both resting and activated cells. The C-terminal region of p40phox responsible for the interaction contains a characteristic stretch of amino acids designated as the PC motif, that also exists in other signal-transducing proteins from yeast to human. Intensive site-directed mutagenesis to the motif in p40phox revealed that it plays a critical role in the binding to p67phox. Thus the PC motif appears to represent a novel module for protein-protein interaction used in a variety of signaling pathways.

Aluminum taken up by transferrin-independent iron uptake affects the iron metabolism in rat cortical cells

We previously demonstrated that cultured human fibroblasts internalize iron via transferrin-independent iron uptake (Tf-IU), redox, and receptor-mediated endocytosis uptake systems [Oshiro, S., Nakajima, H., Markello, T., Krasnewich, D., Bernardini, I., and Gahl, W.A. (1993) J. Biol. Chem. 268, 21586 21591]. Of these iron transport systems, the Tf-IU system is involved in the accumulation of transition metals in various mammalian cells. It is also known that in experimental animals fed aluminum (Al), Al at micromolar level selectively accumulates in the brain. In the present study, we examined the effects of Al accumulated in the brain cells on iron transport by the Tf-IU system and iron metabolism, using primary cultures from fetal rat cerebral cortex. Pretreatment of cells with 200 microM Al-nitrilotriacetate upregulated the Tf-IU system for iron. Moreover, of various metals tested, Al markedly upregulated the Tf-IU activity. To examine the influence of Al on iron metabolism, the interaction between Al accumulated in the cells and iron-responsive element binding protein (IRE-BP), a cellular iron regulator, was examined by Northern blot analysis, and activity assay: Al decreased the Tf receptor mRNA level and increased the aconitase activity of IRE-BP. The increase of aconitase activity by Al was also observed in vitro. These results suggest that Al accumulated in cortical cells affects iron metabolism.

Triple extramammary Paget's disease

BACKGROUND

Triple extramammary Paget's disease (TEPD) has been considered to be rare in the English literature, and its incidence and characteristics are unclear. There are many therapeutic options for treating extramammary Paget's disease (EPD).

OBJECTIVE

Our purpose was to investigate how many TEPD cases have been reported previously and to describe their characteristics. We also describe the effectiveness of radiotherapy for them.

METHODS

We report two TEPD cases, and summarize previously reported TEPD cases together with our cases.

RESULTS

Twenty-three TEPD cases have been reported previously. Of these, 19 cases have been in Japan. All but one patient with TEPD were male. Their axillary lesions often showed no eruptions or very slight erythema. Radiotherapy for our cases was effective although the effectiveness of radiotherapy is controversial.

CONCLUSION

In genital Paget's disease bilateral axillae should be examined histologically, even if they show no or slight eruptions. Radiotherapy may be useful for EPD, particularly axillary Paget's disease.

Perianal Paget's disease years after rectal adenocarcinoma removal

BACKGROUND

Perianal Paget's disease often coincides with anorectal carcinoma, which extends into the epidermis from a contiguous organ.

OBJECTIVE

Our purpose was to present a patient with perianal Paget's disease who had a rectal adenocarcinoma excised 14 years previously in another hospital and to determine whether there is a relationship between the perianal Paget's disease and the rectal adenocarcinoma.

METHODS

We examined the resected specimens of the rectal adenocarcinoma and the perianal Paget's disease histologically.

RESULTS

In the resected specimen of the rectal adenocarcinoma, Paget cells were present within the anal epidermis adjacent to the rectal adenocarcinoma. The Paget cells showed the same histochemical and immunohistological findings as the adenocarcinoma cells.

CONCLUSION

There was a close relationship between the perianal Paget's disease and the rectal adenocarcinoma. It is probable that the Paget cells were derived from direct spread from the rectal adenocarcinoma.

p32 protein, a splicing factor 2-associated protein, is localized in mitochondrial matrix and is functionally important in maintaining oxidative phosphorylation

Human p32, originally cloned as a splicing factor 2-associated protein, has been reported to interact with a variety of molecules including human immunodeficiency virus Tat and complement 1q (C1q). p32 protein is supposed to be in the nucleus and on the plasma membrane for the association with human immunodeficiency virus Tat and C1q, respectively. None of the interactions, however, is proven to have a physiological role. To investigate the physiological function of p32, we determined the intracellular localization of p32. The fractionation of cells, fluorescent immunocytochemistry, and electron microscopic immunostaining show that p32 is exclusively localized in the mitochondrial matrix. We cloned a Saccharomyces cerevisiae homologue of human p32 gene, referred to yeast p30 gene. The yeast p30 protein is also localized in the mitochondrial matrix. The disruption of the p30 gene caused the growth retardation of yeast cells in a glycerol medium but not in a glucose medium, i.e. the impairment of the mitochondrial ATP synthesis. The growth impairment was restored by the introduction of the human p32 cDNA, indicating that p30 is a functional yeast counterpart of human p32. Taken together, both p32 and p30 reside in mitochondrial matrix and play an important role in maintaining mitochondrial oxidative phosphorylation.

Autoantibody reactive with the human general transcription factor TFIIF in sera from patients with autoimmune disorders

Transcription factor (TF) IIF, a heteromeric protein composed of two subunits, RAP30 and RAP74, is required for both specific initiation and elongation of mRNA synthesis by RNA polymerase II. We have identified high titre of specific autoantibodies against the RAP74 subunit of TFIIF in sera from patients with systemic lupus erythematosus (SLE) as well as those with rheumatoid arthritis (RA), periarteritis nodosa (PN), Sjögren's syndrome (SS), dermatomyositis (DM), and mixed connective tissue disease (MCTD) by Western blot or immunoprecipitation. The epitopes recognized by autoantibodies were shown to be preferentially clustered at the central charged region. Anti-RAP74 autoantibody was shown to suppress the activity of TFIIF-stimulated elongation of mRNA synthesis by RNA polymerase II. It is concluded that some patients with autoimmune disorders develop specific autoantibodies against the RAP74 subunit of TFIIF.

Phosphorylation of human general transcription factors TATA-binding protein and transcription factor IIB by DNA-dependent protein kinase--synergistic stimulation of RNA polymerase II basal transcription in vitro

DNA-dependent protein kinase (DNA-PK) has been known to catalyze phosphorylation of a number of regulatory factors involved in DNA replication and transcription such as simian virus 40 T antigen, p53, c-Myc, Sp1, and RNA polymerase II (Pol II). We examined the possibility that DNA-PK phosphorylates the general transcription factors TATA-binding protein (TBP) and transcription factor (TF) IIB, which play key roles in the formation of transcription initiation complex with Pol II. By using a highly purified preparation of DNA-PK from Raji cells, both TBP and TFIIB were shown to be phosphorylated in vitro by DNA-PK. We then investigated the effect of the phosphorylation of these factors on Pol II basal transcription. Stepwise analysis of preinitiation complex formation by electrophoretic mobility shift assay revealed that the phosphorylation of TBP and TFIIB by DNA-PK did not affect the formation of promoter (P)-TBP and P-TBP-TFIIB complexes but synergistically stimulated the formation of P-TBP-TFIIB-TFIIF-Pol II complex. Similarly, combination of the phosphorylated TBP and TFIIB synergistically stimulated Pol II basal transcription from adenovirus major late promoter. These observations suggest that DNA-PK could positively regulate the Pol II basal transcription by phosphorylating TBP and TFIIB.

Telomerase elevation in pancreatic ductal carcinoma compared to nonmalignant pathological states

Telomerase activity was measured in surgically resected tissues of 20 human pancreatic ductal carcinomas, 12 adenomas, 5 pancreatitis tissues, 14 normal pancreatic ducts, and 13 normal pancreatic tissues (primarily made up of acinar cells) using a PCR-based telomerase assay. Relative telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of a human pancreatic cancer cell line, MIA PaCa-2, per microgram of protein in the tissue samples. The median value (25th percentile, 75th percentile) of relative telomerase activity in pancreatic carcinomas was 13.2 (3.58, 244), which was significantly higher relative to normal tissues, normal ducts, pancreatitis tissues, and adenomas (P < 0.0001). When the cutoff value of relative telomerase activity was set at 1.00 and 3.00, the positivity rates of telomerase activity in pancreatic ductal carcinomas were 100 and 80%, respectively. Some of the adenoma samples displayed a weak telomerase ladder. However, when semiquantitatively analyzed, the relative telomerase activity of all adenoma tissues was less than 1.00 equivalent cells per microgram protein of the tissues, which was equivalent to the values encountered in normal ducts. Thus, our results indicate that reactivation of telomerase may occur at a late stage of pancreatic ductal carcinogenesis. Therefore, telomerase may be a specific marker for distinguishing pancreatic cancer from pancreatitis and adenomas.

Characterization of the human thrombopoietin gene promoter. A possible role of an Ets transcription factor, E4TF1/GABP

Thrombopoietin (TPO), the ligand for c-Mpl, is a cytokine that regulates megakaryocyte growth and development. We have cloned the 5'-flanking region of the human TPO gene and analyzed its promoter activity. The human TPO gene promoter lacks a TATA box and directs transcription initiation at multiple sites over a 50-nucleotide region. Transient expression in a human liver cell line (PLC) of promoter fragment-luciferase reporter gene constructs containing a series of 5'-truncated sequences or site-directed mutations identified a sequence 5'-ACTTCCG-3' from -69 to -63 as a positive cis-acting element for high level expression of TPO gene. This sequence contains a core motif (C/A)GGA(A/T) for Ets family proteins in the noncoding strand. Gel mobility shift assays performed with nuclear protein from PLC cells identified a DNA binding protein(s) specific for the element. Anti-E4TF1-60(GABPalpha) or anti-E4TF1-53/47(GABPbeta) antibodies supershifted the complex in gel shift assay. Furthermore, co-expression of E4TF1-60 and E4TF1-53/47 squelched TPO gene expression in PLC and HepG2 cells. It is concluded that Ets family transcription factor E4TF1(GABPalpha/beta), an ubiquitously expressed protein, is required for high level expression of the TPO gene in liver.

Inhibition of the nerve growth factor-induced outgrowth of neurites by trichostatin A requires protein synthesis de novo in PC12D cells

Trichostatin A (TSA) inhibits the activity of histone deacetylase and blocks both oncogenic ras-induced and nerve growth factor-induced (NGF-induced) outgrowth of neurites from PC12 cells. Cells of the PC12D subline extend neurites very rapidly in response to NGF, basic fibroblast growth factor (bFGF), dibutyryl cAMP (dbcAMP) and to staurosporine, even in the presence of an inhibitor of RNA synthesis, as do primed PC12 cells or cultured sympathetic neurons. TSA at 100 nM selectively blocked the NGF- and bFGF-induced outgrowth of neurites from PC12D cells, but not the outgrowth induced by dbcAMP or staurosporine. The NGF-induced changes in morphology with the relocalization of F-actin, were not inhibited by TSA. However, the subsequent formation of growth cones and the outgrowth of neurites was blocked. The activation of mitogen-activated protein (MAP) kinases in NGF-stimulated cells was also unaffected by TSA. When TSA was added to cells that were extending neurites in response to NGF, the number of neurite-bearing cells decreased after a lag period. In the presence of inhibitors of RNA or protein synthesis namely, actinomycin D, cordycepin, and cycloheximide, TSA no longer blocked the NGF- and bFGF-dependent outgrowth of neurites from PC12D cells. Regardless of the effect of TSA, the rapid outgrowth of neurites from PC12D cells was unaffected by the presence of cycloheximide, which inhibited protein synthesis by 97%, as determined by monitoring the incorporation of [35S]methionine/cysteine. This study provides proof that the NGF-induced elongation of neurites does not require protein synthesis de novo. These observations suggest that TSA might not inhibit the early signal-transduction pathway of NGF, but might block the late pathway, which is related to the formation of growth cones and/or neurites. Cellular conditions that no longer allow the NGF- and bFGF-mediated elongation of neurites might be produced by TSA via synthesis of some specific protein(s) due to changes in RNA(s) synthesis de novo.

Semi-quantitative analysis of telomerase in pancreatic ductal adenocarcinoma

Using a polymerase chain reaction-based amplification assay, we measured telomerase activity in surgically resected pancreatic ductal carcinomas (n = 16 cases) and normal ducts (n = 6), comparing findings with the telomerase activity of a human pancreatic cancer cell line, MIA PaCa-2, as a standard, i.e., relative telomerase activity was determined. Telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of MIA PaCa-2 per microgram protein of tissue samples. The median value for telomerase activity in normal pancreatic ducts was 0.13 and the 25th and 75th percentile were 0.01 and 0.76. The median value for telomerase activity in pancreatic ductal adenocarcinoma was 34.7 (25th percentile, 4.98; and 75th percentile, 296), significantly higher than that of normal ducts (P < 0.001). When the cut-off value was set at 1.0 and 3.0, the telomerase positivity rate of pancreatic ductal adenocarcinomas was 100% and 81.3%, respectively. Telomerase may be specific marker for pancreatic ductal carcinomas.