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151.
Thymidine phosphorylase inhibits apoptosis induced by cisplatin 总被引:8,自引:0,他引:8
Ikeda R Furukawa T Mitsuo R Noguchi T Kitazono M Okumura H Sumizawa T Haraguchi M Che XF Uchimiya H Nakajima Y Ren XQ Oiso S Inoue I Yamada K Akiyama S 《Biochemical and biophysical research communications》2003,301(2):358-363
An angiogenic factor, platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP), stimulates the chemotaxis of endothelial cells and confers resistance to apoptosis induced by hypoxia. 2-Deoxy-D-ribose, a degradation product of thymidine generated by TP, partially prevents hypoxia-induced apoptosis. TP is expressed at higher levels in tumor tissues compared to the adjacent non-neoplastic tissues in a variety of human carcinomas. High expression of TP is associated with an unfavorable prognosis. To investigate the effect of TP on cisplatin-induced apoptosis, human leukemia Jurkat cells were transfected with wild-type or mutant (L148R) TP cDNA. TP inhibited a number of steps in the cisplatin-induced apoptotic pathway, activation of caspases 3 and 9 and mitochondrial cytochrome c release. These findings suggest a mechanism by which TP confers resistance to apoptosis induced by cisplatin. Moreover, mutant TP that has no enzymatic activity also suppressed cisplatin-induced apoptosis. These findings indicate that TP has cytoprotective functions against cytotoxic agents which are independent of its enzymatic activity. 相似文献
152.
Akhand AA Ikeyama T Akazawa S Kato M Hossain K Takeda K Suzuki H Takahashi M Nakashima I 《Biochemical and biophysical research communications》2002,292(4):826-831
By use of a specifically sulfhydryl group-reactive chemical, 1,4-butanediyl-bismethanethiosulfonate (BMTS), we studied the localization of oxidative stress-responsive target cysteines for activation of a receptor-type protein tyrosine kinase, c-RET. The chemical, which reacted with RET proteins on the cell surface for sulfhydryl-linked aggregation, induced autophosphorylation and activation of RET kinase. When extracellular domain-deleted RET mutant (RET-PTC-1) cells were exposed to BMTS, neither the molecular status nor the activity of the enzyme was affected, suggesting that the target cysteines of BMTS to which cells were exposed for reaction are located in the cysteine-rich region of the extracellular domain of RET kinase. Despite this result, the exposure of a subcellular form of c-RET or RET-PTC-1 kinase isolated by immunoprecipitation to BMTS did induce activation of the enzyme. These results suggest that cysteines in both the extracellular and the intracellular domains of RET can work as target sites of accessible BMTS and possibly other oxidative elements for structural modification and activation of RET kinase. 相似文献
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Okazaki H Osuga J Tsukamoto K Isoo N Kitamine T Tamura Y Tomita S Sekiya M Yahagi N Iizuka Y Ohashi K Harada K Gotoda T Shimano H Kimura S Nagai R Yamada N Ishibashi S 《The Journal of biological chemistry》2002,277(35):31893-31899
Cholesterol ester (CE)-laden foam cells are a hallmark of atherosclerosis. To determine whether stimulation of the hydrolysis of cytosolic CE can be used as a novel therapeutic modality of atherosclerosis, we overexpressed hormone-sensitive lipase (HSL) in THP-1 macrophage-like cells by adenovirus-mediated gene delivery, and we examined its effects on the cellular cholesterol trafficking. We show here that the overexpression of HSL robustly increased neutral CE hydrolase activity and completely eliminated CE in the cells that had been preloaded with CE by incubation with acetylated low density lipoprotein. In these cells, cholesterol efflux was stimulated in the absence or presence of high density lipoproteins, which might be at least partially explained by the increase in the expression of ABCA1. Importantly, these effects were achieved without the addition of acyl-CoA:cholesterol acyltransferase inhibitor, cAMP, or even high density lipoproteins. Furthermore, the uptake and degradation of acetylated low density lipoprotein was significantly reduced probably by decreased expression of scavenger receptor A and CD36. Notably, the cells with stimulated CE hydrolysis did not exhibit either buildup of free cholesterol or cytotoxicity. In conclusion, increased hydrolysis of CE by the overexpression of HSL leads to complete elimination of CE from THP-1 foam cells not only by increasing efflux but also by decreasing influx of cholesterol. 相似文献
156.
Jervis Vermal Thevathasan Elisabeth Tan Hui Zheng Yu-Chun Lin Yang Li Takanari Inoue Marc Fivaz 《Molecular biology of the cell》2013,24(14):2228-2237
Self-amplification of phosphoinositide 3-kinase (PI3K) signaling is believed to regulate asymmetric membrane extension and cell migration, but the molecular organization of the underlying feedback circuit is elusive. Here we use an inducible approach to synthetically activate PI3K and interrogate the feedback circuitry governing self-enhancement of 3′-phosphoinositide (3-PI) signals in NIH3T3 fibroblasts. Synthetic activation of PI3K initially leads to uniform production of 3-PIs at the plasma membrane, followed by the appearance of asymmetric and highly amplified 3-PI signals. A detailed spatiotemporal analysis shows that local self-amplifying 3-PI signals drive rapid membrane extension with remarkable directional persistence and initiate a robust migratory response. This positive feedback loop is critically dependent on the small GTPase HRas. Silencing of HRas abrogates local amplification of 3-PI signals upon synthetic PI3K activation and results in short-lived protrusion events that do not support cell migration. Finally, our data indicate that this feedback circuit is likely to operate during platelet-derived growth factor–induced random cell migration. We conclude that positive feedback between PI3K and HRas is essential for fibroblasts to spontaneously self-organize and generate a productive migratory response in the absence of spatial cues. 相似文献
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Motohiko Ukiya Takashi Kikuchi Harukuni Tokuda Keiichi Tabata Yumiko Kimura Takanari Arai Yoichiro Ezaki Osamu Oseto Takashi Suzuki Toshihiro Akihisa 《化学与生物多样性》2010,7(8):1871-1884
Nineteen known triterpenoids, 1 – 19 , and one known sesquiterpenoid, 20 , were isolated from dammar resin obtained from Shorea javanica K. & V. (Dipterocarpaceae). One of the acidic triterpenoids, dammarenolic acid ( 1 ), was converted to fourteen derivatives, namely, an alcohol, 21 , an aldehyde, 22 , and twelve L ‐amino acid conjugates, 23 – 34 . Compounds 1 – 34 were examined for their inhibitory effects on the induction of Epstein–Barr virus early antigen (EBV‐EA) by 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) in Raji cells, a known primary screening test for antitumor promoters. All of the compounds tested, except for compounds 4, 5, 12 – 14, 16 , and 17 , showed inhibitory effects against EBV‐EA activation with potencies either comparable with or stronger than that of β‐carotene, a known natural antitumor promoter. In addition, (20S)‐20‐hydroxy‐3,4‐secodammara‐4(28),24‐dien‐3‐al ( 22 ) exhibited inhibitory effects on skin tumor promotion in an in vivo two‐stage mouse skin carcinogenesis test based on 7,12‐dimethylbenz[a]anthracene (DMBA) as initiator, and with TPA as promoter. Furthermore, evaluation of the cytotoxic activities of compounds 1 – 34 against human cancer cell lines showed that reduction (i.e., 21 and 22 ) or conjugation with L ‐amino acids (i.e., 23 – 34 ) of compound 1 enhanced the cytotoxicity against human melanoma cell line CRL1579. 相似文献
160.
Satomi Mezuki Kenji Fukuda Tomonaga Matsushita Yoshihisa Fukushima Ryu Matsuo Yu-ichi Goto Takehiro Yasukawa Takeshi Uchiumi Dongchon Kang Takanari Kitazono Tetsuro Ago 《BMC neurology》2017,17(1):217