RESUMEN
BACKGROUND: Boron neutron capture therapy usually relies on soluble, rather than particulate, boron compounds. This study evaluated the use of a novel boron nanoparticle for boron neutron capture therapy. MATERIALS AND METHODS: Two hundred and fifty thousand B16-OVA tumour cells, pre-incubated with boron nanoparticles for 12 hours, were injected subcutaneously into C57BL/6J mice. The tumour sites were exposed to different doses of neutron radiation one, four, or eight days after tumour cell inoculation. RESULTS: When the tumour site was irradiated with thermal neutrons one day after injection, tumour growth was delayed and the treated mice survived longer than untreated controls (median survival time 20 days (N = 8) compared with 10 days (N = 7) for untreated mice). CONCLUSION: Boron nanoparticles significantly delay the growth of an aggressive B16-OVA tumour in vivo by boron neutron capture therapy.
Asunto(s)
Terapia por Captura de Neutrón de Boro/métodos , Melanoma Experimental/prevención & control , Melanoma Experimental/radioterapia , Nanopartículas/uso terapéutico , Neutrones/uso terapéutico , Animales , Línea Celular Tumoral , Femenino , Ratones , Ratones Endogámicos C57BL , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
In the fission yeast Schizosaccharomyces pombe, there are relatively few signal peptides available and most reports of their activity have not been comparative. Using sequence information from the S. pombe genome database we have identified three putative signal peptides, designated Cpy, Amy and Dpp, and compared their ability to support secretion of green fluorescent protein (GFP). In the comparison we also included the two well-described secretion signals derived from the precursors of, respectively, the Saccharomyces cerevisiae alpha-factor and the S. pombe P-factor. The capability of the tested signal peptides to direct secretion of GFP varied greatly. The alpha-factor signal did not confer secretion to GFP and all the produced GFP was trapped intracellular. In contrast, the Cpy signal peptide supported efficient secretion of GFP with yields approximating 10 mg/L. We also found that the use of an attenuated version of the S. cerevisiae URA3 marker substantially increases vector copy number and expression yield in fission yeast.
Asunto(s)
Señales de Clasificación de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Schizosaccharomyces/genética , Catepsina A/química , Proteínas Fúngicas/genética , Vectores Genéticos , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/genética , Humanos , Plásmidos , Proteínas Recombinantes de Fusión/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/química , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
To examine whether the fission yeast Mam1 ABC transporter can be used for secretion of heterologous proteins, thereby bypassing the classical secretion pathway, we have analyzed chimeric forms of the M-factor precursor. It was demonstrated that GFP can be exported when fused to both the amino-terminal prosequence from mfm1 and a CaaX motif. This secretion was dependent on the Mam1 transporter and not the classical secretion pathway. The secretion efficiency of GFP, however, was relatively low and most of the reporter protein was trapped in the vacuolar membranes. Our findings suggest that the Mam1 ABC protein is a promiscuous peptide transporter that can accommodate globular proteins of a relatively large size. Furthermore, our results help in defining the sequences required for processing and secretion of natural M-factor.