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PubMedDate not supplied

Detection of nitroaromatic compounds on coal combustion particles.

Mutagenic and nonmutagenic extracts of fly ash from fluidized bed combustion were analyzed to determine the compounds responsible for the direct mutagenic activity (mutagenic activity that does not require added metabolic enzymes in the Salmonella mutagenicity assay). Some nitro derivatives of polycyclic aromatic hydrocarbons which are direct acting mutagens were detected by tandem triple quadrupole mass spectrometry. Treatment of a mutagenic and a nonmutagenic extract with excess N2O4 resulted in 28- and 3200-fold increases, respectively, in direct mutagenicity in Salmonella typhimurium strain TA98 and an increase in the relative abundance of nitroaromatic compounds. Polycyclic aromatic compounds were also detected and tentatively identified by gas chromatography-mass spectrometry. Since, previous studies have shown that polycyclic aromatic hydrocarbons may react with NO2 to form direct-acting mutagens, it appears that the direct-acting mutagens in these fly ash extracts may be products of reactions of polycyclic aromatic hydrocarbons with NOX in the combustion gases.

Coal↗
PubMed2005

Diels-alder adducts of 3,6-dibromophencyclone with short-chain N-n-alkylmaleimides: 1H and 13C nuclear magnetic resonance studies of hindered rotations and magnetic anisotropy, and ab initio calculations for optimized structures.

3,6-Dibromophencyclone, 2, reacted with N-ethylmaleimide, 3a; N-n-propylmaleimide, 3b; and N-n-butylmaleimide, 3c; to form the corresponding Diels-Alder adducts, 4a, 4b, and 4c. The nuclear magnetic resonance (NMR) spectra of the adducts were studied at ambient temperatures at 300 MHz for proton and 75 MHz for carbon-13. Full proton assignments were achieved by high-resolution COSY45 spectra for the aryl proton regions. Rigorous assignments for protonated carbons were obtained with the heteronuclear chemical shift correlation spectra (HETCOR). Slow exchange limit (SEL) spectra were observed for both proton and carbon-13 NMR for each adduct, with slow rotation on the NMR timescales for the unsubstituted bridgehead phenyl groups. Endo Diels-Alder adduct stereochemistry was supported by substantial magnetic anisotropic shielding effects in the 1H NMR spectra of the alkyl groups. Proton NMR shifts are compared with those previously reported for the corresponding adducts, 5b and 5c, obtained from 3b and 3c, respectively, with the parent compound, phencyclone, 1. Results of ab initio molecular modeling calculations at the Hartree-Fock level using the LACVP* basis set for conformers of the dibrominated adducts, 4a-4c, are presented, together with HF/6-31G* results for the non-brominated adducts, 5a, 5b, and 5c. Novel aspects of this present work include: (a) attempts to quantitatively evaluate alkyl proton NMR shielding magnitudes in the adducts, relative to maleimide precursors, and (b) use of ab initio Hartree-Fock level calculations to try to reconcile adduct geometries with the observed shielding magnitudes. Our results here complement and extend studies of: (a) adducts of the parent phencyclone with straight-chain N-n-alkylmaleimides, and (b) adducts of 3,6-dibromophencyclone with other symmetrical dienophiles.

Anisotropy↗
PubMedDate not supplied

Studies on the active principles of Schisandra sphenanthera Rehd. et Wils. The structures of schisantherin A, B, C, D, E, and the related compounds.

Deoxyschisandrin (VIII) and five new lignans, named schisantherin A, B, C, D, and E, were isolated from the active fraction of the fruits of Schisandra sphenanthera Rehd. et Wils. Their configurations and conformations were established by exhaustive spectral analysis as well as chemical degradations as shown in Ia, Ib; IIa, IIb; IIIa, IIIb; IVa, IVb, and Va, Vb respectively, and their absolute configurations at biphenyl, at C6, C7, and C8 were all assigned to be S form. The position of the methylenedioxyl group in the structures of gamma-schisandrin and Wuweizisu C (as described in the literature), isolated from Schisandra chinensis, must be corrected as shown in VI and VII respectively. In pharmacologica studies and preliminary clinical trials, schisantherin A, B, C, and D showed good effect in lowering the serum glutamic-pyruvic transaminase level of the patients suffering from chronic virus hepatitis. Schisantherin E and deoxyschisandrin were not effective.

Animals↗
PubMed1990

Differential mutagenicity of two dihydrophenalene congeners: examination of formaldehyde generation and reactive intermediate formation as possible mechanisms.

Compounds in the dihydrophenalene series are currently under investigation as potential antipsychotic agents. The mutagenicity of two compounds in this series was evaluated in several strains in the Ames Salmonella (2,3-dihydro-N,N-dimethyl-1H-phenalen-2-amine:HCI) was less mutagenic than its monomethyl analogue, U-64,273A. Two hypothesis-the of formaldehyde and release of formaldehyde and the formation of macromolecular reactive intermediates--were evaluated as possible mechanisms for the observed mutagenicity. Formaldehyde release during biotransformation of U-65,556A but not U-64,273 was demonstrated, as measured by trapping with the Nash reagent. Thus, formaldehyde release does not correlate with the mutagenic potency of these compounds. Covalent binding of U-65,556A-[3H] equivalents to rat hepatic protein was observed, but binding to DNA, which is considered the more critical target molecule, was not observed. These data suggest that reactive intermediate formation does not explain the mutagenicity of U-65,556A in the Ames Salmonella assay. Follow-up studies were conducted to assess the possible contribution of tritium exchange to the observed covalent binding to protein by quantitatively recovering 3H2O from incubations containing U-65,556A-[3H] and rat liver microsomes. Data indicate that enzyme-dependent formation of 3H2O does occur but that this phenomenon does not account for U-65,556A-[3H]-derived, protein-bound tritium in covalent binding studies.

Animals↗
PubMed1989

Comparative lung tumorigenicity of parent and mononitro-polynuclear aromatic hydrocarbons in the BLU:Ha newborn mouse assay.

A BLU:Ha newborn mouse lung adenoma bioassay was employed to compare the tumorigenicity of selected mononitroarenes and unsubstituted parent compounds 6 months after initial treatment. The presence of a nitro group had a variable effect upon compound potency in which tumorigenicity was increased, abolished, or unchanged. On the basis of results with equimolar doses, the potency of benzo[a]pyrene was greater than 6-nitrobenzo[a]pyrene (inactive), 6-nitrochrysene was much greater than chrysene (inactive), 3-nitrofluoranthene (active) was equal to fluoranthene (active), and 1-nitropyrene (inactive) was equivalent to pyrene (inactive). The potency series among the mononitroarenes was 6-nitrochyrsene much greater than 3-nitrofluoranthene greater than 6-nitrobenzo[a]pyrene (inactive) = 1-nitropyrene (inactive). Lung tumor incidence and multiplicity were similar for both males and females. No consistent pattern was observed for the occasional appearance of lymphoma or hepatic nodular hyperplasia in the various treatment groups.

Adenoma↗
PubMed1991

Comparative fluorometric study of benzo(a)pyrene and aza-aromatic hydrocarbon penetration and metabolism kinetics in the skin of hairless mice.

The kinetics of penetration and metabolism of BaP, BACs, DB(a,h)ACs and DB(c,g)Cs in the skin of hairless mice was studied. The relative fluorescence intensities were measured during three hours after applying 10 nmoles of the compound to the interscapular region of the mice. By using a kinetical model which combines a non-steady diffusion of a hydrocarbon through the stratum corneum and the metabolic oxidation by epidermal cells, the rate constants for the two processes were calculated. It has been shown that B(a)AC, B(c)AC and 12-MB(a)AC penetrate into the skin and are oxidized by epidermal cells more efficiently than BaP. In contrast, alkyl-DB(a,h)ACs (except 14-MDB(a,h)AC) show a great stability in the mouse skin. The carcinogenic BaP, 7-MB(c)AC and DB(a,h)AC have average rates of elimination from the skin.

Animals↗
PubMed1995

Exposure of the deck crew to carcinogenic agents on oil product tankers.

Work on deck on eight oil product tankers was examined. The purpose was to evaluate the need for improvement of the working environment to reduce the risk of occupational cancer. Benzene, polyaromatic hydrocarbons (PAHs) and organic lead compounds were sampled, and the crew answered a questionnaire on acute health effects. By area monitoring, benzene was generally found to be in the range from the detection limit, of 0.01 ppm, up to 1.15 ppm, but one tanker which loaded gasoline with the hatches open had levels up to 55 ppm. Personal monitoring showed exposure levels in the range 0.01-1.15 ppm. The PAH-levels and the levels of organic lead were low. No seamen were observed using respiratory protective equipment. Central nervous system symptoms were reported by the crew with the highest exposures to benzene although benzene may not be the only cause. The exposure to benzene and other hydrocarbons on the deck of oil product tankers ought to be reduced.

Air Pollutants, Occupational↗
PubMedDate not supplied

Evaluation of worker exposure to asphalt paving fumes using traditional and nontraditional techniques.

Forty-five workers at 11 paving sites across the United States were evaluated for exposure to paving asphalt (bitumen) fumes. Traditional measures of exposure such as total particulate matter (TPM) and benzene soluble matter (BSM) were monitored. In addition, total organic matter (TOM), which includes both the BSM residue and the more volatile components that pass through the filter and are collected on sorption material, was quantified and further characterized using a gas chromatography technique and a recently developed fluorescence test. The latter method, which indirectly estimates the content of four- to six-ring polycyclic aromatic compounds, is used as a predictor of carcinogenicity. The correlation between fluorescence emission intensity and carcinogenicity for 36 laboratory generated fume fractions, as measured in a mouse skin-painting bioassay, was then used to estimate the carcinogenic potential of worker monitoring samples. Emission levels, and therefore predicted carcinogenicity, for these samples were at least 17-fold below the value corresponding to a minimal carcinogenic effect. This result was consistent with more extensive chemical analysis (using gas chromatography/mass spectrometry) of two of the samples, which showed the predominant constituents to be alkanes, monocycloparaffins, alkyl-benzenes, alkyl-naphthalenes, and alkyl-benzothiophenes. The geometric mean exposures for all worker studies were 0.21 mg/m3 (TPM), 0.06 mg/m3 (BSM), and 1.23 mg/m3 (TOM).

Adult↗
PubMed2003

Multiple biomarkers study in painters in a shipyard in Korea.

Shipbuilding workers are exposed to a variety of genotoxic compounds including polycyclic aromatic hydrocarbons (PAHs). A limited number of studies have been conducted to evaluate biomarkers related to PAH exposure in painters in the shipyard industry. We examined this in 208 workers recruited from a shipyard located in South Korea. Employees were grouped into three exposure groups: (1) 111 painters using coal tar paints, (2) 70 painters using general paints, and (3) 27 on-site controls using no paints. Levels of urinary 1-hydroxypyrene glucuronide (1-OHPG), as internal dose of PAH exposure, were measured by synchronous fluorescence spectroscopy. Glutathione S-transferase (GST) M1 and T1 genotypes were assessed by a multiplex polymerase chain reaction (PCR)-based method, aromatic-DNA adducts in peripheral white blood cells were measured by 32P-postlabeling, and glycophorin A (GPA) variant frequencies in red blood cells were assessed by flow cytometry. Information on demographic characteristics, smoking habits, diet, job title and use of personal protective equipment (e.g. respiratory and dermal) were collected by self-administered questionnaire. Average urinary 1-OHPG levels in coal tar paint (2.24 micromol/mol creatinine) and general paint (1.38 micromol/mol creatinine) users were significantly higher than in on-site controls (0.62 micromol/mol creatinine) (P<0.001). Paint use, irrespective of the type of paints, and smoking (yes/no) were positively associated with urinary 1-OHPG levels, whereas green tea consumption (yes/no) was negatively associated with the 1-OHPG levels. No significant effect in the 1-OHPG levels were observed for the GSTM1 and GSTT1 genotypes. Aromatic-DNA adduct levels tended to be higher in coal tar paint users (P = 0.06) and painters (P = 0.07) compared to on-site controls. No differences in adduct levels were observed, between the two groups of painters, and the combined group showed greater adduct levels than on-site controls (P = 0.05). GPA mutation frequencies measured in 55 individuals with MN heterozygote genotypes were not significantly different among the three exposure groups, and no correlation was observed between urinary 1-OHPG levels and aromatic-DNA adducts or GPA mutation frequency. These results suggest that painters in the shipyard were exposed to significant amounts of PAHs and possibly to other genotoxic aromatic compounds, and that urinary 1-OHPG may be a potential biomarker of PAH exposure in this population.

Adult↗
PubMed1995

Characterization of the cysteine-rich region of the Caenorhabditis elegans protein Unc-13 as a high affinity phorbol ester receptor. Analysis of ligand-binding interactions, lipid cofactor requirements, and inhibitor sensitivity.

The Caenorhabditis elegans Unc-13 protein is a novel member of the phorbol ester receptor family having a single cysteine-rich region with high homology to those present in protein kinase C (PKC) isozymes and the chimaerins. We expressed the cysteine-rich region of Unc-13 in Escherichia coli and quantitatively analyzed its interactions with phorbol esters and related analogs, its phospholipid requirements, and its inhibitor sensitivity. [3H]Phorbol 12,13-dibutyrate [3H]PDBu bound with high affinity to the cysteine-rich region of Unc-13 (Kd = 1.3 +/- 0.2 nM). This affinity is similar to that of other single cysteine-rich regions from PKC isozymes as well as n-chimaerin. As also described for PKC isozymes and n-chimaerin, Unc-13 bound diacylglycerol with an affinity about 2 orders of magnitude weaker than [3H]PDBu. Structure-activity analysis revealed significant but modest differences between recombinant cysteine-rich regions of Unc-13 and PKC delta. In addition, Unc-13 required slightly higher concentrations of phospholipid for reconstitution of [3H]PDBu binding. Calphostin C, a compound described as a selective inhibitor of PKC, was also able to inhibit [3H]PDBu binding to Unc-13, suggesting that this inhibitor is not able to distinguish between different classes of phorbol ester receptors. In conclusion, although our results revealed some differences in ligand and lipid cofactor sensitivities, Unc-13 represents a high affinity cellular target for the phorbol esters as well as for the lipid second messenger diacylglycerol, at least in C. elegans. The use of phorbol esters or some "specific" antagonists of PKC does not distinguish between cellular pathways involving different PKC isozymes or novel phorbol ester receptors such as n-chimaerin or Unc-13.

Amino Acid Sequence↗
PubMed1992

Apical and basolateral Na/H exchange in cultured murine proximal tubule cells (MCT): effect of parathyroid hormone (PTH).

Kidney proximal tubule Na/H exchange is inhibited by PTH. To analyze further the cellular mechanisms involved in this regulation we have used MCT cells (a culture of SV-40 immortalized mouse cortical tubule cells) grown on permeant filter supports. Na/H exchange was measured using single cell fluorescence microscopy (BCECF) and phosphate transport (measured for comparisons) by tracer techniques. MCT cells express apical and basolateral Na/H exchangers which respond differently to inhibition by ethylisopropylamiloride and by dimethylamiloride, the basolateral membrane transporter being more sensitive. Apical membrane Na/H exchange was inhibited by PTH (10(-8) M; by an average of 25%); similar degrees of inhibition were observed when cells were exposed either to forskolin, 8-bromo-cAMP or phorbol ester. Basolateral membrane Na/H exchange was stimulated either by incubation with PTH (to 129% above control levels) or by addition of phorbol ester (to 120% above control levels); it was inhibited after exposure to either forskolin or 8-bromo-cAMP. The above effects of PTH and phorbol ester (apical and basolateral) were prevented by preincubation of cells with protein kinase C antagonists, staurosporine and calphostin C; both compounds did not affect forskolin or 8-bromo-cAMP induced effects. PTH also inhibited apical Na-dependent phosphate influx (29% inhibition at 10(-8) M); it had no effect on basolateral phosphate fluxes (Na-dependent and Na-independent). Incubation with PTH (10(-8) M) resulted in a rapid and transient increase in [Ca2+]i (measured with the fluorescent indicator, fura-2), due to stimulation of a Ca2+ release from intracellular stores. Exposure of MCT cells to PTH did not elevate cellular levels of cAMP. Taken together, these results suggest that PTH utilizes in MCT cells the phospholipase C/protein kinase C pathway to differently control Na/H exchangers (apical vs. basolateral) and to inhibit apical Na/Pi cotransport.

Alkaloids↗
PubMed2001

Preliminary risk assessment of the wet landscape option for reclamation of oil sands mine tailings: bioassays with mature fine tailings pore water.

Chemical and biological assays have been carried out on the "pore water" that results from the settling of the tailings that accompany bitumen recovery from the Athabasca oil sands. Examination of the nonacidic extracts of pore water by gas chromatography-mass spectroscopy allowed the identification of numerous two- to three-ring polycyclic aromatic compounds (PACs), to a total concentration of 2.6 micrograms/L of pore water. The PACs were biodegraded by microflora naturally present in the pore water. Acute toxicity was associated principally with the acidic fraction (naphthenic acids) of pore water extracts according to the Microtox assay; other work has shown that acute toxicity dissipates fairly rapidly. Both individual PACs and concentrated pore water extracts showed minimal levels of binding to the rat Ah receptor and induced minimal ethoxyresorufin-O-deethylase activity in primary rat hepatocytes, showing an insignificant risk of inducing monooxygenase activity. Taken together with previous work showing negligible mutagenic activity of these extracts, we conclude that it should be possible to develop tailing slurries into biologically productive artificial lakes.

Animals↗
PubMed1990

Xenobiotic-inducible expression of murine glutathione S-transferase Ya subunit gene is controlled by an electrophile-responsive element.

Glutathione S-transferase (GST) Ya subunit gene expression is induced in mammalian tissues by two types of chemical agents: (i) planar aromatic compounds (e.g., 3-methylcholanthrene, beta-naphthoflavone, and 2,3,7,8-tetrachlorodibenzo-p- dioxin) and (ii) electrophiles (e.g., trans-4-phenyl-3-buten-2-one and dimethyl fumarate) or compounds easily oxidized to electrophiles (e.g., tert-butylhydroquinone). To study the mechanism of this induction, we have introduced deletions in the 5' flanking region of a mouse GST Ya subunit gene, fused it to the coding sequence for chloramphenicol acetyltransferase (CAT) activity, and transfected the Ya-CAT genes for expression into hepatoma cells. We show that a single cis-regulatory element, between nucleotides -754 and -713 from the start of transcription, is responsible for the induction by both planar aromatic and electrophilic compounds. Using murine hepatoma cell mutants defective in either the Ah-encoded aryl hydrocarbon receptor (BPrc1 mutant) or in cytochrome P1-450 gene (c1 mutant), we show that induction by planar aromatic but not by electrophilic inducers requires a functional Ah receptor and cytochrome P1-450 activity. From this it is concluded that Ya gene activation by planar aromatic compounds involves metabolism of these inducers by the phase I xenobiotic-metabolizing cytochrome P1-450 system into electrophilic compounds, which is consistent with a recently proposed model [Prochaska, H. J. & Talalay, P. (1988) Cancer Res. 48, 4776-4782]. Therefore, the regulatory sequence of the Ya gene should be considered an electrophile-responsive element (EpRE) activated exclusively by inducers containing an electrophilic center. An EpRE-containing 41-bp oligonucleotide ligated at the -187 site of the Ya gene promoter confers upon it an increase in basal activity and xenobiotic inducibility. The basal activity augments with the number of EpRE copies. DNase I protection patterns show the protection of the EpRE domain by a nuclear factor(s) that becomes more abundant upon exposure of Hepa 1c1c7 cells to tert-butylhydroquinone.

Animals↗
PubMed1984

Role of cytochrome P-450 and related enzymes in the pulmonary metabolism of xenobiotics.

The lung metabolizes a wide variety of xenobiotics and, in the process, forms products that may be more or less toxic than the parent compound. The consequence of metabolism, activation or detoxication, is a function of the nature of the substrate and of the characteristics and concentrations of the enzymes involved. As a result, the biotransformation of xenobiotics can lead to their excretion or to the formation of reactive products that produce deleterious effects by binding covalently to tissue macromolecules. Among the enzymes that metabolize xenobiotics, those associated with the cytochrome P-450-dependent monooxygenase system are probably the most important. The route by which a given substrate is metabolized in a tissue or cell is, to a great extent, determined by the types and concentrations of cytochrome P-450 isozymes present. We are just beginning to understand the distribution of these enzymes in lung and to appreciate the species and cellular differences that exist.

Animals↗
PubMed1995

The CAT-Tox (L) assay: a sensitive and specific measure of stress-induced transcription in transformed human liver cells.

Identifying and measuring the molecular mechanisms of toxicity is an important goal in hazard assessment. We have developed an assay in transformed human liver cells to simultaneously measure the transcriptional responses of 14 stress promoter- or response element-chloramphenicol acetyl transferase (CAT) fusion constructs that are stably integrated into the HepG2 cell line. This assay can measure a wide spectrum of stresses, both toxic and nontoxic, such as protein and protein biosynthesis perturbations, DNA damage, heavy metals, and planar aromatic hydrocarbons. We found that each promoter or response element can be induced by one or more of four chemicals that were tested in the assay. These results have been interpreted in light of the current models of action for each compound. The responses of this assay system can distinguish among compounds that are closely related in their structure and have been shown previously to elicit similar biological activities in simple assay systems. We have designated this technique the CAT-Tox (L)iver assay. It measures a broad range of cellular stresses and toxicants at levels that were comparable to or below those of established methods. The induction profiles generated using the CAT-Tox (L) assay can help to elucidate the molecular mechanisms by which chemicals exert their actions on human cells. These profiles can be indicative of both toxic and nontoxic processes that are occurring in the cell. We propose that this cellular stress assay can serve as a screen for a variety of substances at the molecular level.

Base Sequence↗
PubMed1989

Formation of chlorinated PAH--a possible health hazard from water chlorination.

Four PAH compounds, fluorene, anthracene, fluoranthene and benzo(a)pyrene were dissolved in humus poor (lake) and humus rich water. The samples were chlorinated, stored for three days, and extracted with cyclohexane. Chlorinated derivatives of the four compounds were synthesised and used as calibration standards for quantitative analysis of the corresponding chlorinated PAH formed during the experiment. The synthesized chlorinated PAH were tested for mutagenic activity by the Ames test, and their octanol/water partition coefficient (Pow) were determined by thin layer chromatography. Chlorinated fluorene, fluoranthene and benzo(a)pyrene were formed during chlorination of PAH polluted lake water, but not during chlorination of the humus rich water samples. All chlorinated PAH except 9,10-dichloroanthracene, acted as strong mutagens both in the presence and in the absence of metabolic activation, while benzo(a)pyrene was the only mutagen active parent PAH. The determined Pow showed high lipophilicity for all chlorinated PAH. Theoretically determined bioconcentration factors (BCF) were found to be extremely high, and increased with increasing ring number and increasing number of chlorine atoms attached to the ring.

Anthracenes↗
PubMed1985

Formation, occurrence and analysis of polychlorinated dibenzofurans, dioxins and related compounds.

In several accidents (fires, explosions) involving electrical systems containing polychlorinated biphenyls (PCBs) or benzenes (PCBZs), the formation of polychlorinated tricyclic aromatic compounds such as polychlorinated dibenzofurans (PCDFs), dibenzo-p-dioxins (PCDDs) and biphenylenes (PCBPs) was observed. These findings were not surprising in light of our previous studies on the formation of PCDFs and PCDDs from the thermolysis (500-750 degrees C in presence of air) of PCBs or PCBZs. In these experiments we identified three main and a fourth minor reaction pathway leading to PCDFs from PCBs. The three main reactions involved the loss of ortho-Cl2, and the losses of ortho-HCl with and without a 2,3-chlorine shift. The fourth, minor reaction route found with some PCBs, involved the loss of ortho-H2. These reaction pathways were intramolecular cyclizations via oxidation to phenolic compounds. Thermolysis of commercial PCBs (Aroclor 1254 and 1260) yielded the same PCDF isomers as expected from the main PCB components via these four reaction pathways; the isomers formed included the toxic 2,3,7,8-substituted tetra-, penta- and hexa-CDFs. Thermolysis of PCBZs involved complex condensation reactions with multiple rearrangements leading to PCDFs as well as PCDDs. Again oxidation to phenolic products was involved but the reaction routes are not yet fully elucidated. The results of samples from transformer and capacitor accident sites showed very complex PCDF mixtures with 2,3,7,8-substituted isomers as main components and originating from the PCBs in the transformer liquid. The unusual presence of PCDDs in samples from the Binghamton accident originates from PCBZs present in transformer fluid of that specific installation, thus confirming our previous thermolysis findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Occupational↗
PubMed1994

Light-dependent induction of early-response gene expression by calphostin-C.

Calphostin-C is a compound possessing the ability to inhibit protein kinase C (PKC) by oxidative modification in vitro and to enhance the epidermal growth factor (EGF) receptor phosphorylation in vivo in a light-dependent manner. Here, we found that calphostin-C induced c-fos and c-jun mRNA accumulation in the lung adenocarcinoma cell line A549 in a light-dependent manner. Nuclear run-on assay revealed that this mRNA accumulation took place at the transcription level. However, unlike in vitro, calphostin-C did not inhibit cytosolic PKC activity in vivo, and the gene expression induced by calphostin-C was inhibited by another PKC inhibitor, staurosporine. Thus, it was suggested that calphostin-C activates cytosolic PKC-dependent signaling pathway to the induction of "early-response gene" expression in a light-dependent manner.

Adenocarcinoma↗