RESUMEN
Oxaliplatin (OHP) treatment of colorectal cancer (CRC) frequently leads to resistance. OHP resistance was induced in CRC cell lines LoVo-92 and LoVo-Li and a platinum-sensitive ovarian cancer cell line, A2780, and related to cellular platinum accumulation, platinum-DNA adducts, transporter expression, DNA repair genes, gene expression arrays, and array-CGH profiling. Pulse (4 h, 4OHP) and continuous exposure (72 h, cOHP) resulted in 4.0 to 7.9-fold and 5.0 to 11.8-fold drug resistance, respectively. Cellular oxaliplatin accumulation and DNA-adduct formation were decreased and related to OCT1-3 and ATP7A expression. Gene expression profiling and pathway analysis showed significantly altered p53 signaling, xenobiotic metabolism, role of BRCA1 in DNA damage response, and aryl hydrocarbon receptor signaling pathways, were related to decreased ALDH1L2, Bax, and BBC3 (PUMA) and increased aldo-keto reductases C1 and C3. The array-CGH profiles showed focal aberrations. In conclusion, OHP resistance was correlated with total platinum accumulation and OCT1-3 expression, decreased proapoptotic, and increased anti-apoptosis and homologous repair genes.
Asunto(s)
Neoplasias Colorrectales/tratamiento farmacológico , Resistencia a Antineoplásicos/genética , Neoplasias Ováricas/tratamiento farmacológico , Oxaliplatino/efectos adversos , Apoptosis/efectos de los fármacos , Proteínas Reguladoras de la Apoptosis/genética , Proteína BRCA1/genética , Línea Celular Tumoral , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Hibridación Genómica Comparativa , Aductos de ADN/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Reparación del ADN/efectos de los fármacos , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Transportador 1 de Catión Orgánico/genética , Neoplasias Ováricas/genética , Neoplasias Ováricas/patología , Oxaliplatino/farmacología , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH/genética , Proteínas Proto-Oncogénicas/genética , Proteína p53 Supresora de Tumor/genética , Proteína X Asociada a bcl-2/genéticaRESUMEN
A great number of fluorescent probes have been developed for detecting singlet oxygen (1O2), which is considered to be one of the most effective reactive oxygen species (ROS), especially in clinical applications. The commercially available fluorescent probe Singlet Oxygen Sensor Green (SOSG) is widely used due to its reported high selectivity to 1O2. In this study, we carried out systemic experiments to determine the activation of SOSG in the presence of ionizing radiation. The results show that the SOSG probe exhibits a pronounced fluorescence increase as a function of radiation dose delivered by gamma-rays as well as X-rays, in conditions where the formation of singlet oxygen is not expected. Furthermore, scavenger tests indicate that hydroxyl radicals may be involved directly or indirectly in the activation process of SOSG although the exact mechanism remains unknown.
RESUMEN
This letter is meant to make scientists aware of the proper application of transmission electron microscopy (TEM) for the assessment of polymeric self-assemblies. Cryogenic (cryo)-TEM should be the method of choice. Here, we show the difference in morphologies observed in the same sample when using cryo-TEM and when using TEM with drying, demonstrating the importance of choosing the proper method.
RESUMEN
BACKGROUND: Single photon emission computed tomography (SPECT) is an indispensable tool in the determination of the in vivo fate of polymeric micelles. However, for this purpose, the micelles need to be radiolabeled, and almost all radiolabeling procedures published to date involve the conjugation of a chelating agent to the constituting polymer, which could actually affect their biodistribution. In this paper, we report a new facile method for radiolabeling polystyrene-b-poly(ethylene oxide) diblock copolymer micelles without the necessity of any chemical modification. Instead, we entrap the radiolabel (i.e., (111)In) in the micellar core during the formation of the micelles by using tropolone as lipophilic ligand. METHODS: Micelles were prepared by emulsifying a polymer solution in chloroform with a buffer containing (111)In and lipophilic ligand tropolone, by stirring for about 2 h. The produced micelles were physically characterized by means of dynamic light scattering and transmission electron microscopy. The biological properties of the radiolabeled micelles were determined by means of in vivo and ex vivo evaluation. SPECT analysis was done on Balb/c-nu mice, after administration of 1 mg micelles containing 22 MBq of (111)In. SPECT images were obtained over 24 h. Biodistribution of the micelles was assessed also ex vivo. RESULTS: The radiolabeling method is robust and reproducible with constant radiolabeling efficiency (~30 %) even at indium concentrations that are much higher than the necessary for in vivo studies, and the radiolabel retention is more than 80 % in mouse serum at 48 h. Radiolabeled micelles having hydrodynamic radius of 97 ± 13 nm have been successfully evaluated in vivo and ex vivo in non-tumor-bearing mice, revealing significant blood circulation up to at least 24 h post injection, with low accumulation in most organs except for the liver and spleen, which are the natural organs for clearance of nanoparticles. CONCLUSIONS: An easy and robust radiolabeling method has been developed, and its applicability is demonstrated in animal studies, showing its value for future investigation of polymeric micelles as nanocarriers in tumor-bearing mice.
