JNK inhibitor SP600125 is a partial agonist of human aryl hydrocarbon receptor and induces CYP1A1 and CYP1A2 genes in primary human hepatocytes

SP600125, a specific inhibitor of c-Jun-N-Terminal kinase (JNK), was reported as a ligand and antagonist of aryl hydrocarbon receptor (AhR) [Joiakim A, Mathieu PA, Palermo C, Gasiewicz TA, Reiners Jr JJ. The Jun N terminal kinase inhibitor SP600125 is a ligand and antagonist of the aryl hydrocarbon receptor. Drug Metab Dispos 2003;31(11):1279-82]. Here we show that SP600125 is not an antagonist but a partial agonist of human AhR. SP600125 significantly induced CYP1A1 and CYP1A2 mRNAs in primary human hepatocytes and CYP1A1 mRNA in human hepatoma cells HepG2. This effect was abolished by resveratrol, an antagonist of AhR. Consistent with the recent report, SP600125 dose-dependently inhibited CYP1A1 and CYP1A2 genes induction by a prototype AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in human hepatocytes. Moreover, SP600125 displayed typical behavior of a partial agonist in HepG2 cells transiently transfected with a reporter plasmid containing two inverted repeats of the dioxin responsive element or with a plasmid containing 5'-flanking region of human CYP1A1 gene. SP600125 transactivated the reporter plasmids with EC(50) of 0.005 and 1.89 microM, respectively. On the other hand, TCDD-dependent transactivation of the reporter plasmids was inhibited by SP600125 with IC(50) values of 1.54 and 2.63 microM, respectively. We also tested, whether the effects of SP600125 are due to metabolism. Using liquid chromatography/mass spectrometry approach, we observed formation of two minor monohydroxylated metabolites of SP600125 in human hepatocytes, human liver microsomes but not in HepG2 cells. These data imply that biotransformation is not responsible for the effects of SP600125 on AhR signaling. In conclusion, we demonstrate that SP600125 is a partial agonist of human AhR, which induces CYP1A genes.     

Lectin-HPMA copolymer conjugates: potential oral drug carriers for targeting diseased tissues

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer-lectin conjugates were investigated for potential use as targeted oral drug carriers for treatment of inflammatory conditions such as colitis. Wheat germ agglutinin (WGA)-HPMA copolymer and peanut agglutinin (PNA)-HPMA copolymer and fluorescein isothiocyanate (FITC)-labeled WGA- and PNA-HPMA copolymer conjugates were synthesized. Conjugate dissociation constants (K_d) for lectin-carbohydrate binding determined by frontal affinity chromatography indicated that no activity reduction of the lectins occurred during the synthesis of these conjugates. K_d values measured were in good agreement with literature findings for similar lectin-carbohydrate interactions, on the order of 10⁻⁵ M⁻¹. Biorecognition of these conjugates by healthy rat intestinal tissue resulted in differential HPMA copolymer-lectin conjugate binding patterns in the same tissue. HPMA copolymer-WGA conjugate showed strong binding in the healthy rat intestinal tissues, while the HPMA copolymer-PNA conjugate showed minimal, but specific binding. This differential binding suggests that site-specific drug delivery via specific lectin recognition may be feasible for treatment of colon inflammation or cancer.     

HPMA copolymer–anticancer drug–OV-TL16 antibody conjugates. II. Processing in epithelial ovarian carcinoma cells in vitro

The binding, internalization, subcellular trafficking and in vitro cytotoxicity of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer–anti-cancer drug–OV-TL16 antibody (Ab) conjugates in the ovarian carcinoma OVCAR-3 cell line have been investigated. Adriamycin (ADR) and meso chlorin e₆ mono(N-2-aminoethylamide) (Mce₆) photosensitizer were used as anti-cancer drugs. Targeted (Ab-containing) conjugates were compared with non-targeted HPMA copolymer–drug conjugates and with free drugs. Targeted conjugates were taken up rapidly by cells and detected within lysosomes by confocal fluorescence microscopy. The ADR attached to polymer chains via a degradable GFLG spacer was released from the conjugate, diffused via the lysosomal membrane into the cytoplasm and ultimately accumulated in the cell nuclei. In contrast, conjugates containing ADR bound via the GG spacer accumulated in the lysosomes, but no fluorescence could be detected in the cell nuclei. Binding the drugs to a non-targeted HPMA copolymer decreased their cytotoxicity in vitro. The IC₅₀ dose increased from 2 μM for free ADR to 150 μM for P(GFLG)–ADR (P is the HPMA copolymer backbone) and from 0.34 μM for free Mce₆ (with light) to 290 μM for P–(GG)–Mce₆. However, attachment of OV-TL16 Abs rendered HPMA copolymer–drug conjugates biorecognizable by OVCAR-3 cells and markedly increased their cytotoxicity. The IC₅₀ doses were 4.4 and 0.38 μM for the targeted conjugates P(GFLG)–ADR–Ab and P(GG)–Mce₆–Ab (with light), respectively. Biorecognition was shown to be specific by inhibition experiments with free Ab. The findings indicate the potential of these conjugates as effective agents in the treatment of ovarian cancer. Int. J. Cancer 75:600–608, 1998. © 1998 Wiley-Liss, Inc.     

Synthesis of semitelechelic poly[N-(2-hydroxypropyl)methacryl-amide] by radical polymerization in the presence of alkyl mercaptans

The free radical polymerization of N-(2-hydroxylpropyl)methacrylamide (HPMA) in the presence of chain transfer agents was studied. Methyl 3-mercaptopropionate (MMP) and 2-mercaptoethylamine (MEA) were used as chain transfer agents and 2,2′-azobisisobutyronitrile (AIBN) was used as the initiator. Semitelechelic (ST) polymers produced under various reaction conditions were analyzed by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and size exclusion chromatography (SEC). The molecular weight of the ST polymers was regulated by the initial molar ratio of chain transfer agent to HPMA. The free radicals formed by the decomposition of AIBN initiated a fraction of polymer chains; such chains were not terminated in a functional group. The amount of these polymer chains depended on the concentration and efficiency of the chain transfer agent, concentration of AIBN, and conversion. Decreasing the concentration of AIBN and increasing the concentration of the chain transfer agent reduced the formation of nonfunctionalized polymer chains.     

Synthesis and significant cytostatic activity of 7-hetaryl-7-deazaadenosines

A series of 7-aryl- and 7-hetaryl-7-deazaadenosines was prepared by the cross-coupling reactions of unprotected or protected 7-iodo-7-deazaadenosines with (het)arylboronic acids, stannanes, or zinc halides. Nucleosides bearing 5-membered heterocycles at the position 7 exerted potent in vitro antiproliferative effects against a broad panel of hematological and solid tumor cell lines. Cell cycle analysis indicated profound inhibition of RNA synthesis and induction of apoptosis in treated cells. Intracellular conversion to triphosphates has been detected with active compounds. The triphosphate metabolites showed only a weak inhibitory effect on human RNA polymerase II, suggesting potentially other mechanisms for the inhibition of RNA synthesis and quick onset of apoptosis. Initial in vivo evaluation demonstrated an effect of 7-(2-thienyl)-7-deazaadenine ribonucleoside on the survival rate in syngeneic P388D1 mouse leukemia model.     

Influence of Oral Antidiabetic Drugs on Hyperglycemic Response to Foods in Persons with Type 2 Diabetes Mellitus as Assessed by Continuous Glucose Monitoring System: A Pilot Study

Background

The purpose of this prospective open-label trial was (1) to assess the influence of oral antidiabetic drugs (OAD) on the glycemic index (GI), glucose response curves (GRCs), daily mean plasma glucose (MPG) and (2) to compare the GI of foods in persons with OAD-treated type 2 diabetes mellitus (T2DM) with the respective GI in healthy persons (HP).

Methods

Tested foods containing 50 g of carbohydrates were eaten for breakfast and dinner after 10 and 4 h of fasting, respectively. Glycemic index, GRC, and MPG were obtained using the CGMS^®System Gold™ (CGMS). In T2DM patients [n = 16; age (mean ± standard error) 56.0 ± 2.25 years], foods were tested four times: tests 1, 2, and 3 were performed within one week in which placebo was introduced on day 2, and test 4 was carried out five weeks after reintroduction of OAD. Glycemic indexes, GRC, and MPG from tests 1, 2, 3, and 4 were compared. In a control group of 20 HP (age 24.4 ± 0.71 years), the mean GIs were calculated as the mean from 20 subject-related GIs.

Results

In T2DM patients, subject-related assessment of GIs, GRC, and MPG distinguished persons with and without OAD effect. Nevertheless, the group-related GIs and the MPG on days 2, 8, and 39 showed no significant difference. There was no significant difference between the GIs in OAD-treated T2DM patients (test 4) versus HP (except in apple baby food). Glucose response curves were significantly larger in T2DM patients (test 4) versus HP.

Conclusions

Determination of GRC and subject-related GI using the CGMS appears to be a potential means for the evaluation of efficacy of OAD treatment. Further studies are underway.     

Saccharide-mediated interactions of boar sperm surface proteins with components of the porcine oviduct

The role of boar seminal plasma proteins attached to the sperm plasma membrane during ejaculation has been studied in saccharide-mediated events in the female reproductive tract. Heparin-binding (Hep(+)) proteins (DQH sperm surface protein, and AQN and AWN spermadhesins) and their aggregated forms (fractions II and III) interacted more strongly with both oviductal epithelium cells and fluid than non-heparin-binding (Hep(-)) proteins (PSP I and PSP II spermadhesins) and their heterodimer (fraction IV), and interactions correlate with affinity of these proteins to yeast mannan. Indirect immunofluorescence (IMF) showed that the AQN 1 spermadhesin and fraction II bind to the apical glycocalyx of the ampulla, as well as the isthmic and uterine tubal junction regions of the oviductal sections. IMF demonstrated the recognition of AQN 1 and fraction II and mannosyl components of oviductal epithelium. We suggest that Hep(+) proteins (especially AQN 1, fraction II) on sperm could enable sperm binding to oviductal epithelium and thus participate in formation of the sperm oviductal reservoir. Interactions of Hep(+) proteins to oviductal epithelium were inhibited by mannan, hyaluronic acid and sialylated O-glycoproteins. No or slight inhibition was observed with sulphated polysaccharides (heparin, chondroitin sulphate) and simple monosaccharides. Besides that, attachment of boar seminal plasma proteins to oviductal epithelium cells was affected by oviductal fluid, the natural environment in the oviduct. Moreover, the ability of hyaluronic acid to inhibit the interaction of sperm surface proteins to the oviduct might play a role in sperm release from the oviductal reservoir and in the capacitation process.     

Inverse correlation between plasma Beta-carotene and interleukin-6 in patients with advanced coronary artery disease

The interrelationships between plasma beta-carotene, alpha-tocopherol, and the level of systemic inflammation and oxidative stress were investigated in patients with advanced coronary artery disease (CAD). Plasma beta-carotene, alpha-tocopherol, malondialdehyde, free radicals, interleukin-6, high sensitive C-reactive protein levels, and other risk factors of CAD were determined in a group of patients with advanced CAD [significant stenosis according to coronarographic examination (n=91) and a control group of examined patients with coronary arteries with no stenosis (n=49)]. Between-group differences in continuous variables were analyzed with the Hotelling T2-test (software NCSS2000), analyses of correlation matrix with the software STATISTICA. Advanced CAD coincided with significantly lower plasma concentrations of high-density lipoprotein (HDL)-cholesterol and beta-carotene as well as with elevated levels of all inflammatory markers, but only with mild increase of oxidative stress. Beta-carotene significantly inversely correlated with interleukin-6. This inverse correlation could suggest potential protective effect of beta-carotene on atherosclerosis due to the inhibition of inflammatory processes.