A novel synthetic compound, (Z)-5-(3-hydroxy-4-methoxybenzylidene)-2-iminothiazolidin-4-one (MHY773) inhibits mushroom tyrosinase

As part of continued efforts for the development of new tyrosinase inhibitors, (Z)-5-(substituted benzylidene)-2-iminothiazolidin-4-one derivatives (1a – 1l) were rationally synthesized and evaluated for their inhibitory potential in vitro. These compounds were designed and synthesized based on the structural attributes of a β-phenyl-α,β-unsaturated carbonyl scaffold template. Among these compounds, (Z)-5-(3-hydroxy-4-methoxybenzylidene)-2-iminothiazolidin-4-one (1e, MHY773) exhibited the greatest tyrosinase inhibition (IC₅₀ = 2.87 μM and 8.06 μM for monophenolase and diphenolase), and outperformed the positive control, kojic acid (IC₅₀ = 15.59 and 31.61 μM). The kinetic and docking studies demonstrated that MHY773 interacted with active site of tyrosinase. Moreover, a melanin quantification assay demonstrated that MHY773 attenuates α-melanocyte-stimulating hormone (α-MSH) and 3-isobutyl-1-methylxanthine (IBMX)-induced melanin contents in B16F10 melanoma cells. Taken together, these data suggest that MHY773 suppressed the melanin production via the inhibition of tyrosinase activity. MHY773 is a promising for the development of effective pharmacological and cosmetic agents for skin-whitening.     

l-2-Hydroxyglutarate dehydrogenase: identification of a novel enzyme activity in rat and human liver. Implications for l-2-hydroxyglutaric acidemia

In this paper we studied the degradation of l-2-hydroxyglutarate in tissues from rat and man in order to try and find the underlying basis for the accumulation of this metabolite in l-2-hydroxyglutaric patients. The results show that l-2-hydroxyglutarate is not degraded by an oxidase but via a dehydrogenase which was found to be present in liver only. This newly identified enzyme activity was characterized kinetically, although the nature of the reaction product remains to be identified.     

Modulation of aortic protein phosphorylation by benzo(a)pyrene: Implications in PAH-induced atherogenesis

The toxicity of polycyclic aromatic hydrocarbons such as benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, and 3-methylcholanthrene has been associated with alterations in the proliferation of vascular smooth muscle cells and the development of lesions of mesenchymal origin. Because phosphorylation of endogenous substrates plays a central role in the regulation of smooth muscle cell growth, the present studies were conducted to evaluate the phosphorylation pattern of medial aortic protein upon repeated in vivo exposure of Japanese quail to benzo(a)pyrene (BaP). Medial aortic homogenates from quail treated for 10 weeks with 10 mg/kg benzo(a)pyrene or vehicle were processed for in vitro measurements of protein phosphorylation. In vitro phosphorylation of endogenous or exogenous proteins stimulated in vitro by phorbol myristate acetate/phosphatidyl-serine or cyclic AMP, known activators of protein kinase C and cyclic AMP-dependent protein kinase, respectively, was examined in the cytosolic and particulate fractions of homogenates from control and treated animals. Benzo(a)pyrene treatment significantly enhanced the basal phosphorylation of Mr 113, 35, and 23 kDa proteins in the cytosolic fraction. Modest increases in the phosphorylation of Mr 71, 52, and 38 kDa were also observed under basal conditions. No changes in the basal phosphorylation of particulate proteins were observed. Phosphorylation of endogenous protein substrates by protein kinase C in the cytosolic fraction was not altered by benzo(a)pyrene treatment. In contrast, inhibition of C-kinase-mediated phosphorylation of endogenous Mr 272, 72, and 45 kDa proteins was observed in the particulate fraction of aortic homogenates from benzo(a)pyrene-treated quail relative to controls. Exogenous histone phosphorylation by PKC in the particulate, but not cytosolic fraction, was decreased by benzo(a)pyrene treatment. The effects of benzo(a)pyrene on the C-kinase system were specific, since cAMP-mediated phosphorylation of endogenous proteins, as well as exogenous histone, was not altered by benzo(a)pyrene. Interestingly, benzo(a)pyrene treatment was associated with a selective increase of Mr 200, 80, and 67 kDa proteins in the cytosolic fraction. Collectively, these data are consistent with the hypothesis that medial protein phosphorylation is a significant molecular target of benzo(a)pyrene within the vascular wall.     

Stress-mediated modulation of B(alpha)P-induced hepatic CYP1A1: role of catecholamines

The present study investigated the involvement of catecholamines in stress-mediated alterations in CYP1A1 induction by benzo(alpha)pyrene (B(alpha)P) in Wistar rats. This was achieved by measuring EROD activity and CYP1A1 mRNA levels in liver tissue from rats exposed to restraint stress and B(alpha)P coupled with pharmacological modulation of peripheral and central catecholamine levels and different adrenoceptors. In a state of reserpine-induced central and peripheral catecholamine depletion, stress strongly suppressed EROD induction. Peripheral catecholamines do not appear to play a critical role in the stress-mediated modulation of EROD inducibility by B(alpha)P. Stress did not alter EROD inducibility by B(alpha)P when peripheral catecholamines were either depleted by guanethidine or supplemented by peripheral adrenaline administration. On the other hand, central noradrenergic systems appear to have a role in the stress-mediated changes in B(alpha)P-induced EROD activity and Cyp1A1 gene expression. Stimulation or blockade of noradrenaline release with atipamezole and dexmedetomidine, respectively, significantly modified the up-regulating effect of stress. Alpha1 adrenoceptors also appear to participate in the effect of stress on EROD inducibility. Alpha1-blockade with prazosin potentiated the up-regulating effect of stress, possibly preventing the down-regulating effect of noradrenaline. Beta adrenoceptors also seem to be involved directly or indirectly in the stress-mediated modulation of Cyp1A1, as propranolol (beta-antagonist) blocked the down-regulating effect of stress on B(alpha)P-induced Cyp1A1 gene expression. Plasma corticosterone alterations after stress were not related to alterations in the B(alpha)P-induced EROD activity and Cyp1A1 gene expression. In conclusion, stress appears to interfere in the regulation of B(alpha)P-induced hepatic CYP1A1 in an unpredictable manner and via signalling pathways not always directly related to catecholamines. In particular, whenever drug treatment disrupts noradrenergic neurotransmission, other stress-stimulated factors appear to modify the induction of CYP1A1. In summary, regulation of induction of hepatic CYP1A1 during stress appears to involve various components of the stress system, including central and peripheral catecholamines, which interact in a complex manner, yet to be elucidated.     

Reactivity and binding of benzo(a)pyrene diol epoxide to poly(dG-dC).(dG-dC) and poly(dG-m5dC).(dG-m5dC) in the B and Z forms

The physical and covalent binding of the carcinogen benzo(a)pyrene-7,8-diol-9,10-oxide (BaPDE) to poly(dG-dC).(dG-dC) and poly(dG-m5dC).(dG-m5dC) in the B and Z forms were studied utilizing absorbance, fluorescence and linear dichroism techniques. In the case of poly(dG-dC).(dG-dC) the decrease in the covalent binding of BaPDE with increasing NaCl concentration (0.1-4 M) as the B form is transformed to the Z form is attributed to the effects of high ionic strengths on the reactivity and physical binding of BaPDE to the polynucleotides; these effects tend to obscure differences in reactivities with the B and Z forms of the nucleic acids. In the case of poly(dG-m5dC).(dG-m5dC) the B-to-Z transition is induced at low ionic strength (2 mM NaCl + 10 microM Co(NH3)6Cl3) and the covalent binding is found to be 2-3-times lower to the Z form than to the B form. Physical binding of BaPDE by intercalation, which precedes the covalent binding reaction, is significantly lower in the Z form than in the B form, thus accounting, in part, for the lower covalent binding. The linear dichroism characteristics of BaPDE covalently bound to the Z and B forms of poly(dG-m5dC).(dG-m5dC) are consistent with nonintercalative, probably external conformations of the aromatic pyrenyl residues.     

Inhibition of benzo(a)pyrene-induced cell cycle progression by all-trans retinoic acid partly through cyclin D1/E2F-1 pathway in human embryo lung fibroblasts

Benzo(a)pyrene [B(a)P] is a potent environmental carcinogen, which induces cell cycle changes. All-trans retinoic acid (ATRA) is a promising agent in prevention and treatment of human cancers. In the present study, we investigated the inhibition of B(a)P-induced cell cycle progression by ATRA in human embryo lung fibroblast (HELF). Our results showed that after treatment with B(a)P, the expression of cyclin D1 and E2F-1 were both increased significantly in HELF. There were almost no changes of CDK4 and E2F-4 expression by treatment with B(a)P. As expected, pretreatment with ATRA could efficiently decrease B(a)P-induced overexpression of cyclin D1 and E2F-1. In a further study, we stably transfected antisense cyclin D1 and antisense CDK4 plasmid into HELF. The inhibition of cyclin D1 expression and the inhibition of CDK4 expression significantly impaired the B(a)P-induced overexpression of E2F-1 respectively. Pretreatment with ATRA, cells expressing antisense cyclinD1 or antisense CDK4 showed a lesser decrease of B(a)P-induced overexpression of E2F-1 compared with similarly treated HELF. Furthermore, flow cytometry analysis showed that B(a)P promoted cell cycle progression from G(1) phase to S phase, while pretreatment with ATRA could inhibit B(a)P-induced cell cycle progression by an accumulation of cells in the G(1) phase. It was suggested that ATRA could block B(a)P-induced cell cycle promotion partly through the cyclin D1/E2F-1 pathway in HELF.     

5-(Hydroxymethyl)-2-furfural: a selective inhibitor of DNA polymerase lambda and terminal deoxynucleotidyltransferase

5-(Hydroxymethyl)-2-furfural (HMF), a pyrolysate of carbohydrate isolated from instant coffee (Coffea arabica L.), selectively inhibits the activities of mammalian DNA polymerase lambda (pol lambda) and terminal deoxynucleotidyltransferase (TdT) which are family X pols, in vitro. The compound influenced neither the activities of replicative DNA polymerases such as alpha, delta, and epsilon, nor even the activity of pol beta which is from the same family and thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since parts of HMF such as furan, furfuryl alcohol, and 2-furaldehyde did not influence the activities of any enzymes tested, the substituted form of furan with a hyroxymethyl group and a formyl group might be important for the inhibition of pol lambda and TdT. The inhibitory effect of HMF on intact pol lambda (i.e., residues 1-575), a truncated pol lambda lacking the N-terminal BRCA1 C-terminus domain (133-575, del-1 pol lambda) and another truncated pol lambda lacking the N-terminal proline-rich region (245-575, del-2 pol lambda) was dose-dependent, and 50% inhibition was observed at a concentration of 26.1, 10.3, and 4.6 microM, respectively. The IC(50) value of HMF for TdT was the same as that for del-2 pol lambda (5.5 microM). The HMF-induced inhibition of both pol lambda and TdT activities was competitive with respect to both the DNA template-primer and the dNTP substrate. On the basis of these results, HMF was suggested to bind to the pol beta-like region of pol lambda and TdT.     

ERK-dependent induction of TNFalpha expression by the environmental contaminant benzo(a)pyrene in primary human macrophages

Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BP) are toxic environmental contaminants known to enhance production of pro-inflammatory cytokines such as IL-1beta. The present study was designed in order to determine whether TNFalpha, another cytokine acting in inflammation, may also constitute a target for these chemicals. Both TNFalpha mRNA and TNFalpha secretion levels were found to be enhanced in human BP-treated macrophages. Dioxin, a contaminant activating the aryl hydrocarbon receptor (AhR) like PAHs, was also shown to increase TNFalpha expression. BP-mediated TNFalpha induction was however not suppressed by AhR antagonists, making unlikely the involvement of the typical AhR signalling pathway. BP-exposure of macrophages did not enhance NF-kappaB DNA binding activity, but it activated the MAP kinase ERK1/2. In addition, the use of chemical inhibitors of extracellular signal-regulated protein kinase (ERK) activation fully abrogated induction of TNFalpha production in BP-treated macrophages. These data likely indicate that PAHs enhance TNFalpha expression in human macrophages through an ERK-related mechanism. Such a regulation may contribute to confer pro-inflammatory properties to these widely-distributed environmental contaminants.     

Synthesis and biological evaluation of 1-(benzenesulfonamido)-2-[5-(N-hydroxypyridin-2(1H)-one)]acetylene regioisomers: a novel class of 5-lipoxygenase inhibitors

A hitherto unknown class of linear acetylene regioisomers were designed such that a SO₂NH₂ group was located at the ortho-, meta-, or para-position of the acetylene C-1 phenyl ring, and a N-hydroxypyridin-2(1H)-one moiety was attached via its C-5 position to the C-2 position on an acetylene template (scaffold). All three regioisomers inhibited 5-lipoxygenase (5-LOX), where the relative potency order was 2-SO₂NH₂ (IC₅₀ = 10 μM) >3-SO₂NH₂ (IC₅₀ = 15 μM) >4-SO₂NH₂ (IC₅₀ = 68 μM) relative to the reference drug nordihydroguaiaretic acid (NDGA; IC₅₀ = 35 μM). The 2-SO₂NH₂ regioisomer (ED₅₀ = 86.0 mg/kg po) exhibited excellent oral anti-inflammatory (AI) activity that was more potent than aspirin (ED₅₀ = 128.9 mg/kg) and marginally less potent than ibuprofen (ED₅₀ = 67.4 mg/kg). The N-hydroxypyridin-2(1H)one moiety provides a novel pharmacophore for the design of cyclic hydroxamic mimetics capable of chelating 5-LOX iron for exploitation in the design of 5-LOX inhibitory AI drugs.     

Inactivation of the Cullin (CUL)-RING E3 ligase by the NEDD8-activating enzyme inhibitor MLN4924 triggers protective autophagy in cancer cells

The multiunit Cullin (CUL)-RING E3 ligase (CRL) controls diverse biological processes by targeting a mass of substrates for ubiquitination and degradation, whereas its dysfunction causes carcinogenesis. Post-translational neddylation of CUL, a process triggered by the NEDD8-activating enzyme E1 subunit 1 (NAE1), is required for CRL activation. Recently, MLN4924 was discovered via a high-throughput screen as a specific NAE1 inhibitor and first-in-class anticancer drug. By blocking CUL neddylation, MLN4924 inactivates CRL and causes the accumulation of CRL substrates that trigger cell cycle arrest, senescence and/or apoptosis to suppress the growth of cancer cells in vitro and in vivo. Recently, we found that MLN4924 also triggers protective autophagy in response to CRL inactivation. MLN4924-induced autophagy is attributed partially to the inhibition of mechanistic target of rapamycin (also known as mammalian target of rapamycin, MTOR) activity by the accumulation of the MTOR inhibitory protein DEPTOR, as well as reactive oxygen species (ROS)-induced stress. Moreover, the blockage of autophagy response enhances apoptosis in MLN4924-treated cells. Together, our findings not only reveal autophagy as a novel cellular response to CRL inactivation by MLN4924, but also provide a piece of proof-of-concept evidence for the combination of MLN4924 with autophagy inhibitors to enhance therapeutic efficacy.     

Inactivation of the Cullin (CUL)-RING E3 ligase by the NEDD8-activating enzyme inhibitor MLN4924 triggers protective autophagy in cancer cells

The multiunit Cullin (CUL)-RING E3 ligase (CRL) controls diverse biological processes by targeting a mass of substrates for ubiquitination and degradation, whereas its dysfunction causes carcinogenesis. Post-translational neddylation of CUL, a process triggered by the NEDD8-activating enzyme E1 subunit 1 (NAE1), is required for CRL activation. Recently, MLN4924 was discovered via a high-throughput screen as a specific NAE1 inhibitor and first-in-class anticancer drug. By blocking CUL neddylation, MLN4924 inactivates CRL and causes the accumulation of CRL substrates that trigger cell cycle arrest, senescence and/or apoptosis to suppress the growth of cancer cells in vitro and in vivo. Recently, we found that MLN4924 also triggers protective autophagy in response to CRL inactivation. MLN4924-induced autophagy is attributed partially to the inhibition of mechanistic target of rapamycin (also known as mammalian target of rapamycin, MTOR) activity by the accumulation of the MTOR inhibitory protein DEPTOR, as well as reactive oxygen species (ROS)-induced stress. Moreover, the blockage of autophagy response enhances apoptosis in MLN4924-treated cells. Together, our findings not only reveal autophagy as a novel cellular response to CRL inactivation by MLN4924, but also provide a piece of proof-of-concept evidence for the combination of MLN4924 with autophagy inhibitors to enhance therapeutic efficacy.     

Benzo(alpha)pyrene-induced up-regulation of CYP1A2 gene expression: role of adrenoceptor-linked signaling pathways

CYP1A2, a principal catalyst for metabolism of various therapeutic drugs and carcinogens, among others, is in part regulated by the stress response. This study was designed to assess whether catecholamines and in particular adrenergic receptor-dependent pathways, modulate benzo(alpha)pyrene (B(alpha)P)-induced hepatic CYP1A2. To distinguish between the role of central and peripheral catecholamines in the regulation of CYP1A2 induction, the effect of central and peripheral catecholamine depletion using reserpine was compared to that of peripheral catecholamine depletion using guanethidine. The effects of peripheral adrenaline and L-DOPA administration were also assessed. The results suggest that alterations in central catecholamines modulate 7-methoxyresorufin O-demethylase activity (MROD), CYP1A2 mRNA and protein levels in the B(alpha)P-induced state. In particular, central catecholamine depletion, dexmedetomidine-induced inhibition of noradrenaline release and blockade of alpha(1)-adrenoceptors with prazosin, up-regulated CYP1A2 expression. Phenylephrine and dexmedetomidine-induced up-regulation may be mediated, in part, via peripheral alpha(1)- and alpha(2)-adrenoceptors, respectively. On the other hand, the L-DOPA-induced increase in central dopaminergic activity was not followed by any change in the up-regulation of CYP1A2 expression by B(alpha)P. Central noradrenergic systems appeared to counteract up-regulating factors, most likely via alpha(1)- and alpha(2)-adrenoceptors. In contrast, peripheral alpha- and beta-adrenoceptor-related signaling pathways are linked to up-regulating processes. The findings suggest that drugs that bind to adrenoceptors or affect central noradrenergic neurotransmission, as well as factors that challenge the adrenoceptor-linked signaling pathways may deregulate CYP1A2 induction. This, in turn, may result in drug-therapy and drug-toxicity complications.     

Design and total synthesis of (-)-codonopsinine, (-)-codonopsine and codonopsinine analogues by O-(2-oxopyrrolidin-5-yl)trichloroacetimidate as amidoalkylating agent with improved antimicrobial activity via solid lipid nanoparticle formulations

A general strategy towards total synthesis of (-)-codonopsinine, (-)-codonopsine and codonopsinine analogues has been developed from (D)-tartaric acid via the intermediate (3S,4R)-1-methyl-2-oxo-5-(2,2,2-trichloroacetamido)pyrrolidinediacetate (7). α-amidoalkylation studies of 7 with electron rich benzene derivative 8a-g as C-nucleophiles afforded (aryl derivatives) 9a-g. The target compounds 1, 2 and 13c-g were readily obtained from 10a-g via Grignard addition to the homochiral lactam which was produced by deoxygenation using Lewis-acid followed by deacetylation. The synthesized compounds were loaded onto solid lipid nanoparticle formulations (SLNs) prepared by hot emulsification-ultrasonication technique using Compritol as solid lipid and Pluronic f68 as surfactant. SLNs were fully evaluated and the permeation of synthesized compound from SLNs was assayed against non-formulated compounds through dialysis membranes using Franz cell. The data indicated good physical characteristics of the prepared SLNs, sustaining of release profiles and significant improvement of permeation ability when compared to the non-formulated compounds. The antibacterial and antifungal activities of 1, 2 and 13c-g were determined by disc diffusion and microbroth dilution method to determine the minimum inhibitory concentrations (MIC) against seven microorganisms (Staphyloccus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter baumannii and Candida albicans). The most active compounds against the Gram positive S. aureus were 1, 13C, 13d, and 13g. Also, 13c, 13d, and 13e had antibacterial activity but not 13f against some Gram negative organisms (E. coli, and P. mirabilis). MIC concentrations against P. aeruginosa, and K. pneumoniae were?≥512?μg/ml, while that against A. baumannii was?≥128?μg/ml except for nanoformulae of 13e and 13f that were 16 and 64?μg/ml, respectively. No antifungal activity against Candida albicans was recorded for all compounds and their nanoformulae (MIC?>?1024?μg/ml). SLNs were found to decrease the MIC values for some of the compounds with no effect on the antifungal activity. In conclusion, we demonstrated a novel, straight-forward and economical procedure for the total synthesis of (-)-codonopsinine 1, (-)-codonopsine 2 and codonopsinine analogues 13c-g from simple and commercially available starting materials; d-tartaric acid; with antimicrobial activities against Gram positive and Gram-negative organisms that were improved by SLNs formulations.     

Synthesis of (E)-9-(1-pyrenyl)-4-hydroxynon-2-enal, a fluorescent probe of the (E)-4-hydroxynon-2-enal with retained biological properties

(E)-9-(1-pyrenyl)-4-hydroxynon-2-enal (FHNE), a fluorescent probe of (E)-4-hydroxynon-2-enal (HNE) is synthesised in seven steps and in 35% overall yield, starting from commercially available 1-pyrencarboxyaldehyde. When incubated with cultured HeLa cells this fluorescent probe penetrates cells and particularly concentrates in the region surrounding the nucleus. As the parent compound, HNE it is able to induce the activation of heat shock factor (HSF) and it is able to induce the binding of HSF to heat shock element (HSE).     

Inhibition of benzo(a)pyrene-induced carcinogenesis by vitamin C alone and by vitamin C/vitamin E and selenium/glutathione

The reduction on peroxidation caused by benzopyrenes by some naturally occurring antineoplastic agents was studied in this experimental work. Inhibition/reduction of experimental carcinogenesis induced by benzo(a)pyrene by vitamin C alone and by vitamin C/vitamin E and selenium/glutathione was attempted in 224 female Wistar rats divided in four groups. Injected with 10.08 mL benzo(a)pyrene, the animals were treated with some naturally occurring substances like vitamin C alone and a combination of anticarcinogens. By calculating the carcinogenic potency of benzo(a)pyrene and the anticarcinogenic potency of substances used as well as histological examination of developed tumors and survival time of treated animals, it was found that vitamin C exerts a significant anticarcinogenic effect of 8.3 units and that the combination of the two anticarcinogens used produced a significant prolongation of the animals survival time with anticarcinogenic potency of 22.1 and 22.2 units, respectively. This is considered a potent anticarcinogenic effect. The question of an additional supportive administration of such agents complementary to the conventional cancer chemotherapy in humans is raised. Of course, further studies are needed.     

Synthesis of (Z)-2-((1H-indazol-3-yl)methylene)-6-[11C]methoxy-7-(piperazin-1-ylmethyl)benzofuran-3(2H)-one as a new potential PET probe for imaging of the enzyme PIM1

(Z)-2-((1H-Indazol-3-yl)methylene)-6-methoxy-7-(piperazin-1-ylmethyl)benzofuran-3(2H)-one is a potent and selective proviral integration site in moloney murine leukemia virus kinase 1 (PIM1) inhibitor with an IC₅₀ value of 3 nM. (Z)-2-((1H-Indazol-3-yl)methylene)-6-[¹¹C]methoxy-7-(piperazin-1-ylmethyl)benzofuran-3(2H)-one, a new potential PET probe for imaging of the enzyme PIM1, was first designed and synthesized in 20–30% decay corrected radiochemical yield and 370–740 GBq/μmol specific activity at end of bombardment (EOB). The synthetic strategy was to prepare a carbon-11-labeled Boc-protected intermediate followed by a quick acidic de-protection.     

Resolution and Synthesis of (S)-1-(2-Naphthyl)ethanol with Immobilized Pea Protein: As a New Biocatalyst

(S)-1-(2-Naphthyl)ethanol was yielded by immobilized pea (Pisum sativum L.) protein (IPP) from (R, S) 2-naphthyl ethanol (>99% ee, yield; about 50%), in which the (R)-enantiomer was selectively oxidized to 2-acetonaphthone. IPP could be reused consecutively at least three times without any decrease of yield and optical purity.     

Induction of 2',5' oligo(A) synthetase in tumor-bearing mice with encephalomyocarditis (EMC) virus or poly(I)poly(C)

Infection of 13 month-old C3H mice with EMC virus or inoculation with the interferon inducer poly(I)poly(C) results in elevated levels of the enzyme 2',5' oligo(A) synthetase only in animals with spontaneous tumors (breast cancer or hepatomas). High enzymatic activities are detected in homogenates from liver, spleen, plasma and neoplastic cells of the animals with breast carcinomas and only in the neoplastic liver cells of the animals with hepatomas.     

Differential Alterations in Metabolic Pattern of the Spliceosomal UsnRNAs during Pre-Malignant Lung Lesions Induced by Benzo(a)pyrene: Modulation by Tea Polyphenols

The differential alterations of the spliceosomal UsnRNAs (U1, U2, U4, U5, and U6) were reported to be associated with cellular proliferation and development. The attempt was made in this study to analyze the metabolic pattern of the spliceosomal UsnRNAs during the development of pre-malignant lung lesions induced in experimental mice model system by benzo(a)pyrene (BP) and also to see how tea polyphenols, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), modulate the metabolism of these UsnRNAs during the lung carcinogenesis. No significant changes in the level of the UsnRNAs were seen in the inflammatory lung lesions at 9th week due to treatment of BP. However, there was significant increase in the level of U1 (∼2.5 fold) and U5 (∼47%) in the hyperplastic lung lesions at 17th week. But in the mild dysplastic lung lesions at 26th week, the level of UsnRNAs did not change significantly. Whereas, in the dysplastic lung lesions at 36th week there was significant increase in the level of the U2 (∼2 fold), U4 (∼2.5 fold) and U5 (∼2 fold). Due to the EGCG and ECG treatment the lung lesions at 9th week appeared normal and in the 17th, 26th, and 36th week it appeared as hyperplasia. The level of the UsnRNAs was significantly low in the lung lesions at 9th week (only U2 and U4 by EGCG), at 17th week (only U1 by EGCG/ECG), at 26th week (U1 by ECG; U2, U4 and U5 by EGCG/ECG) and at 36th week (U1 by ECG, U2 and U4 by EGCG/ECG). Whereas, there was significant increase in the level of U5 (by EGCG/ECG) and U6 (by EGCG only) in the lung lesions at 36th and 26th week respectively. This indicates that the metabolism of the spliceosomal UsnRNAs differentially altered during the development of pre-malignant lung lesions by BP as well as during the modulation of the lung lesions by the tea polyphenols.