Abstract
Purpose: The efficiency of boron neutron capture therapy (BNCT) depends on the sufficient accumulation of boron-10 in cancer cells. Currently, prompt γ-ray analysis (PGA), inductively coupled plasma (ICP) and α-autoradiography facilities are widely used to measure the boron concentration. These methods are effective to determine the boron-10 average concentration in tumor tissues, but they can not demonstrate boron distribution in detail in tumor tissues and cancer cells. Here, we tried to clarify the boron-10 compound distribution using immunofluorescence staining.
Materials and methods: The human lung carcinoma cell line (A549) was cultured at subconfluent density. The boron-10 compound BPA (p-boronophenylalanine) was dissolved (10B: 1300 ppm) and prepared to study. The A549 cells were incubated with BPA at different 10B concentrations (1.625, 3.25, 6.5, 13, 26 and 52 ppm) for one hour. They were then processed for immunofluorescence staining with anti-BPA monoclonal antibody and Alexa Fluor labeling antibody. In addition, DAPI (4',6-diamino-2-phenylindole) staining was performed to observe the nucleus in cells. The immunofluorescence staining was observed by a fluorescence microscope and the intensity of BPA staining was measured by Adobe Photoshop Software.
Results: The double staining of BPA and DAPI showed that BPA was accumulated mostly in the surrounding of nucleus of A549 cells. The intensity of BPA staining increased with the increasing concentration of 10B. Up to 13 ppm 10B, the intensity of BPA staining increased in a linear dose-dependent manner. In addition, the peak of intensity histogram of 13 ppm 10B staining shifted to the higher intensity area compared with that of 3.25 ppm 10B staining.
Conclusions: In this study, the BPA accumulation in the surrounding of nucleus of A549 cells was investigated by an imaging method in vitro. In future, we will prefer to study the BPA distribution in tumor tissues with this method in vivo.
