Search results for "drug resistance"
showing 10 items of 953 documents
Proteomic profiling of Trastuzumab (Herceptin(R))-sensitive and -resistant SKBR-3 breast cancer cells.
2013
BACKGROUND: The Human Epidermal Growth Factor Receptor 2 (HER-2), overexpressed in 25-30% of breast carcinomas (BC), is the therapeutic target for trastuzumab, a recombinant humanized monoclonal antibody. The initial response to trastuzumab is often followed by drug-insensitivity within one year. Several hypotheses have been raised to explain this event, but the mechanisms behind the responses to trastuzumab are still unclear. Aim: To study the effects of short and prolonged trastuzumab treatment on the proteomic profiles of HER-2-overexpressing SKBR-3 BC cells. MATERIALS AND METHODS: Cells were treated with trastuzumab to obtain sensitive and resistant clones. The drug effects were evaluat…
ChemInform Abstract: Synthesis and Induction of G0-G1 Phase Arrest with Apoptosis of 3,5-Dimethyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,…
2009
The multistep synthesis of 3,5-dimethyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,4-f][1,2,3,5]tetrazepin-4(3H)-one 15 has been carried out. The compound showed antiproliferative and apoptotic effects against K562, K562-R (imatinib mesilate resistant), HL60 and multidrug resistant (MDR) HL60 cell lines. Compound 15 showed a pro-apoptotic activity against HL60 and K562 resistant cell lines markedly higher than etoposide and busulfan, respectively. Flow cytometry studies carried out on K562 cells allowed to establish that 15 induces G0-G1 phase arrest followed by apoptosis.
Cytotoxic activity of secondary metabolites derived from Artemisia annua L. towards cancer cells in comparison to its designated active constituent a…
2010
Artemisia annua L. (sweet wormwood, qinhao) has traditionally been used in Chinese medicine. The isolation of artemisinin from Artemisia annua and its worldwide accepted application in malaria therapy is one of the showcase success stories of phytomedicine during the past decades. Artemisinin-type compounds are also active towards other protozoal or viral diseases as well as cancer cells in vitro and in vivo. Nowadays, Artemisia annua tea is used as a self-reliant treatment in developing countries. The unsupervised use of Artemisia annua tea has been criticized to foster the development of artemisinin resistance in malaria and cancer due to insufficient artemisinin amounts in the plant as c…
Spectrum of pncA Mutations in Multidrug-Resistant Mycobacterium tuberculosis Isolates Obtained in Latvia
2004
Pyrazinamide (PZA) is an effective antituberculous agent ([1][1]) that becomes active when bacterial pyrazinamidase converts it to pyrazinoic acid, which is toxic to mycobacteria ([4][2]). In Mycobacerium tuberculosis , PZA resistance is associated with the loss of pyrazinamidase activity, mainly
Recurrences of multidrug-resistant tuberculosis: Strains involved, within-host diversity, and fine-tuned allocation of reinfections
2020
34 páginas, 13 figuras
Possible Mechanisms for Tumour Cell Sensitivity to TNF-a and Potential Therapeutic Applications
2001
TNF is a macrophage / monocyte-derived cytokine with cytostatic and cytotoxic anti-tumour activity. TNF-alpha can cause haemorrhagic necrosis and regression of experimental tumours. Nevertheless, the TNF-alpha doses required to cure tumour-bearing mice lead to injury of normal tissues and, eventually, may cause a lethal shock syndrome. This toxicity implies severe limitations for the therapeutic use of TNF-a. Reactive oxygen intermediates (ROIs) are involved in TNF-a-induced cell killing. Different studies are consistent with the hypothesis that tumour cell sensitivity to TNF-alpha is related to its capacity to buffer oxidative attack. Recently, we have demonstrated that the sensitivity of …
Antiproliferative activity against leukemia cells of sesquiterpene lactones from the Turkish endemic plant Centaurea drabifolia subsp. detonsa
2017
The apolar organic extract obtained from aerial parts of Centaurea drabifolia Sibth. & Sm. subsp. detonsa (Bornm.) Wagenitz, growing wild in Turkey, was investigated for the first time for its secondary metabolite composition. Seven sesquiterpene lactones belonging to the guaiane class (1-7), including the new compound 4, along with a fatty acid lactone derivative (8), were isolated. The structures of these compounds were established by spectroscopic analysis, including 2D NMR spectroscopic techniques, with the stereostructure of the new guaiane 4 determined with the help of MTPA derivatization. Cytotoxic activities of compounds 1-7 were evaluated against two cancer cell lines, namely acute…
Evolución de la resistencia transmitida y adquirida a fármacos antirretrovirales en pacientes infectados con VIH-1
2018
Introducción: La adquisición y transmisión de resistencia amenaza el éxito del tratamiento antirretroviral. En este estudio evaluamos el comportamiento epidemiológico de las mutaciones de resistencia (MR) a fármacos antirretrovirales del VIH-1 según factores de riesgo y clínicos específicos. Metodología: Este es un estudio retrospectivo observacional de series transversales acumuladas, realizado en la Unidad de Enfermedades Infecciosas de un hospital universitario en España (CHGUV) entre los años 2003 y 2014. Nuestro objetivo fue estimar la evolución de la frecuencia anual de MR a fármacos antirretrovirales en el genoma de la proteasa y transcriptasa inversa del VIH-1 durante el periodo de …
Light-induced resistance of the keratin network to the filament-disrupting tyrosine phosphatase inhibitor orthovanadate.
2003
Epidermal keratinocytes respond to low-dose light irradiation by inducing signaling cascades that lead to long-term effects on gene transcription thereby protecting cells against damage. In contrast, little is known about immediate light-induced alterations of structural proteins. We have made the intriguing observation that light produces fundamental changes in the properties of the keratin filament system of cultured epidermoid A-431 cells. A short light exposure (1–10 min) causes the keratin cytoskeleton to become immediately resistant to the tyrosine phosphatase inhibitor orthovanadate, which otherwise disrupts the keratin filament network completely in just a few minutes. This protecti…
Thymidylate synthase polymorphism and microsatellite instability: association in colorectal cancer.
2005
5-Fluorouracil (5FU) is the main drug used for the treatment of colorectal cancer (CRC) and Thymidilate Synthase (TS) is its target enzyme. TS gene has regulatory tandemly repeated sequences in its 5'' and 3''untraslated region (5''-3'' UTR). CRC often shows a kind of genomic instability called Microsatellite Instability (MSI) that is associated with TS levels and survival. Our data show that the genotype 2R/2R (homozygosity for 2 tandem repeat sequences in the 5''UTR) is more frequently associated with MSI+ and lower TS levels. More over we did not find any significant association between the 2R/3R (heterozygosity for 2 and 3 tandem repeat sequences in the 5''UTR) and 3R/3R (homozygosity f…