Fig. 1. Effects of TBT on neuroblastoma differentiation and tumour growth.

a Representative images of neural outgrowth and immunofluorescence staining. Neural extension and increased expression of ßIII-tubulin were observed in NB-1 cells treated with 1 µM of TBT. Scale bar = 100 µm. b Quantification of neurite length and number. The average neurite length and the number of neurites in a cell were increased in NB-1 cells by treatment with 1 µM of TBT. n.s. non-significant. c Induction of six differentiation marker genes in seven cell lines treated with TBT. Heatmap was drawn using the maximum and minimum values of expression levels of each gene. Information on MYCN amplification status was obtained from previous reports. With the criterion of upregulation of three genes or more among the six genes evaluated, five of the seven cell lines showed differentiation by TBT. d Xenograft growth curves of the TBT- and mock-treated groups. Results are shown as mean ± SE, and statistical significance was tested using an unpaired Student’s t-test (n = 8/vehicle group; n = 6 /TBT group). e Macroscopic view of the xenografts in the two treatment groups. f The therapeutic effect assessed by tumour weight at necropsy. Horizontal bars show the average. Although there was no significant difference in the average tumour weight between mock- and TBT-treated groups, the macroscopic sizes of xenograft tumours in the TBT-treated group were smaller than those of the vehicle-administered group.