TIG3 Tumor Suppressor-Dependent Organelle Redistribution and Apoptosis in Skin Cancer Cells

TIG3 is a tumor suppressor protein that limits keratinocyte survival during normal differentiation. It is also important in cancer, as TIG3 level is reduced in tumors and in skin cancer cell lines, suggesting that loss of expression may be required for cancer cell survival. An important goal is identifying how TIG3 limits cell survival. In the present study we show that TIG3 expression in epidermal squamous cell carcinoma SCC-13 cells reduces cell proliferation and promotes morphological and biochemical apoptosis. To identify the mechanism that drives these changes, we demonstrate that TIG3 localizes near the centrosome and that pericentrosomal accumulation of TIG3 alters microtubule and microfilament organization and organelle distribution. Organelle accumulation at the centrosome is a hallmark of apoptosis and we demonstrate that TIG3 promotes pericentrosomal organelle accumulation. These changes are associated with reduced cyclin D1, cyclin E and cyclin A, and increased p21 level. In addition, Bax level is increased and Bcl-XL level is reduced, and cleavage of procaspase 3, procaspase 9 and PARP is enhanced. We propose that pericentrosomal localization of TIG3 is a key event that results in microtubule and microfilament redistribution and pericentrosomal organelle clustering and that leads to cancer cell apoptosis

Synthesis and application of silylated pyrrolidines : enantioselective organocatalytic synthesis of alpha-trifluoromethyl alpha-amino acid derivatives and copper catalyzed multicomponent reactions

The work presented in this thesis focuses on the synthesis and application of silylated pyrrolidines, chiral phosphoric acid catalyzed Friedel-Crafts reactions to form quaternary trifluoromethylated amino acid derivatives and copper-catalyzed four-component reactions towards functionalized imidates. First, various silylated pyrrolidines were obtained in high yields by asymmetric synthesis. Enantiopure (S)-2-(diphenylmethylsilyl)pyrrolidine was furnished after recrystallization of its HCl salt and the absolute configuration was confirmed by X-ray crystal structure analysis. The application of these Lewis base structures, bearing a silyl group directly attached to the pyrrolidine, in asymmetric Michael-type addition reactions has been demonstrated. The catalyzed enantioselective addition of propanal and butanal to nitroolefins resulted in the desired nitro aldehydes in high yields (up to 99%), diastereoselectivities (up to 97:3 dr) and enantioselectivities (up to 95.5:4.5 er). The second part of this work describes the first Brønsted acid catalyzed Friedel-Crafts reaction to form quaternary amino acids that bear a trifluoromethyl moiety. Trifluoropyruvate imines were selected as substrates for this purpose. These imines were activated by a catalytic amount of TRIP and reacted with a wide variety of indole derivatives to afford the desired compounds in high yields (up to 99%) and enantioselectivities (up to 97.5:2.5 er). The absolute configuration of a representative example was determined by comparison of theoretical and experimental ECD spectra. The deprotection of the 6-chloro derivative with trifluoroacetic acid yielded the free amino ester. In addition to indole derivatives, pyrrole could be used as substrate for this Friedel-Crafts reaction. However, more investigations are necessary to obtain higher yields and enantioselectivities in that case. The last project of this thesis describes the development of copper-catalyzed multicomponent reactions. Terminal alkynes, tosyl azide, methanol and nitroolefins reacted in the presence of triethylamine as base and catalytic amount of copper(I) iodide to form functionalized imidates in one-pot. A wide variety of terminal alkynes and nitroolefins were tolerated to give the desired adducts in high yields (up to 74%) with moderate diastereoselectivities (up to 66:34 dr). The course of this transformation was studied by NMR spectroscopic experiments. Interestingly, an intramolecular example was discovered that led to the formation of a 1,2-dihydroisoquinoline derivative

Synthesis and application of silylated pyrrolidines : enantioselective organocatalytic synthesis of alpha-trifluoromethyl alpha-amino acid derivatives and copper catalyzed multicomponent reactions

The work presented in this thesis focuses on the synthesis and application of silylated pyrrolidines, chiral phosphoric acid catalyzed Friedel-Crafts reactions to form quaternary trifluoromethylated amino acid derivatives and copper-catalyzed four-component reactions towards functionalized imidates. First, various silylated pyrrolidines were obtained in high yields by asymmetric synthesis. Enantiopure (S)-2-(diphenylmethylsilyl)pyrrolidine was furnished after recrystallization of its HCl salt and the absolute configuration was confirmed by X-ray crystal structure analysis. The application of these Lewis base structures, bearing a silyl group directly attached to the pyrrolidine, in asymmetric Michael-type addition reactions has been demonstrated. The catalyzed enantioselective addition of propanal and butanal to nitroolefins resulted in the desired nitro aldehydes in high yields (up to 99%), diastereoselectivities (up to 97:3 dr) and enantioselectivities (up to 95.5:4.5 er). The second part of this work describes the first Brønsted acid catalyzed Friedel-Crafts reaction to form quaternary amino acids that bear a trifluoromethyl moiety. Trifluoropyruvate imines were selected as substrates for this purpose. These imines were activated by a catalytic amount of TRIP and reacted with a wide variety of indole derivatives to afford the desired compounds in high yields (up to 99%) and enantioselectivities (up to 97.5:2.5 er). The absolute configuration of a representative example was determined by comparison of theoretical and experimental ECD spectra. The deprotection of the 6-chloro derivative with trifluoroacetic acid yielded the free amino ester. In addition to indole derivatives, pyrrole could be used as substrate for this Friedel-Crafts reaction. However, more investigations are necessary to obtain higher yields and enantioselectivities in that case. The last project of this thesis describes the development of copper-catalyzed multicomponent reactions. Terminal alkynes, tosyl azide, methanol and nitroolefins reacted in the presence of triethylamine as base and catalytic amount of copper(I) iodide to form functionalized imidates in one-pot. A wide variety of terminal alkynes and nitroolefins were tolerated to give the desired adducts in high yields (up to 74%) with moderate diastereoselectivities (up to 66:34 dr). The course of this transformation was studied by NMR spectroscopic experiments. Interestingly, an intramolecular example was discovered that led to the formation of a 1,2-dihydroisoquinoline derivative

Magnetic resonance angiography in infrapopliteal arterial disease: prospective comparison of 1.5 and 3 Tesla magnetic resonance imaging

PURPOSE: To prospectively determine the accuracy of 1.5 Tesla (T) and 3 T magnetic resonance angiography (MRA) versus digital subtraction angiography (DSA) in the depiction of infrageniculate arteries in patients with symptomatic peripheral arterial disease. PATIENTS AND METHODS: A prospective 1.5 T, 3 T MRA, and DSA comparison was used to evaluate 360 vessel segments in 10 patients (15 limbs) with chronic symptomatic peripheral arterial disease. Selective DSA was performed within 30 days before both MRAs. The accuracy of 1.5 T and 3 T MRA was compared with DSA as the standard of reference by consensus agreement of 2 experienced readers. Signal-to-noise ratios (SNR) and signal-difference-to-noise ratios (SDNRs) were quantified. RESULTS: No significant difference in overall image quality, sufficiency for diagnosis, depiction of arterial anatomy, motion artifacts, and venous overlap was found comparing 1.5 T with 3 T MRA (P > 0.05 by Wilcoxon signed rank and as by Cohen k test). Overall sensitivity of 1.5 and 3 T MRA for detection of significant arterial stenosis was 79% and 82%, and specificity was 87% and 87% for both modalities, respectively. Interobserver agreement was excellent k > 0.8, P < 0.05) for 1.5 T as well as for 3 T MRA. SNR and SDNR were significantly increased using the 3 T system (average increase: 36.5%, P < 0.032 by t test, and 38.5%, P < 0.037 respectively). CONCLUSIONS: Despite marked improvement of SDNR, 3 T MRA does not yet provide a significantly higher accuracy in diagnostic imaging of atherosclerotic lesions below the knee joint as compared with 1.5 T MRA

UV–Vis Monitoring of Radical Polymerizations by Spin Trapping with Chromophoric Nitrones

The application of chromophoric radical spin traps for highly sensitive UV–vis monitoring of conversion of radical enhanced spin capturing polymerizations (ESCP) is presented. In ESCP the growing macroradical is reacting with a nitrone providing the corresponding polymeric nitroxide radical spin trap which will react irreversibly with a second macroradical to eventually give a polymeric alkoxyamine. The progress of styrene and <i>n</i>-butyl acrylate ESC polymerizations in the presence of π-conjugated nitrones is successfully visualized via a significant change of absorbance of the nitrone chromophore in the 200–500 nm range due to the nitrone transformation into an alkoxyamine moiety upon incorporation into the polymer. Moreover, related studies on UV–vis monitoring of photochemical rearrangement of nitrones to their corresponding oxaziridines are discussed