Increased globotriaosylceramide levels in a transgenic mouse expressing human alpha1,4-galactosyltransferase and a mouse model for treating Fabry disease.

Fabry disease is a lysosomal storage disorder caused by an α-galactosidase A (α-Gal A) deficiency and resulting in the accumulation of glycosphingolipids, predominantly globotriaosylceramide (Gb3). A transgenic mouse expressing the human α-Gal A R301Q mutant in an α-Gal A-knockout background (TgM/KO) should be useful for studying active-site-specific chaperone (ASSC) therapy for Fabry disease. However, the Gb3 content in the heart tissue of this mouse was too low to detect an ASSC-induced effect. To increase the Gb3 levels in mouse organs, we created transgenic mice (TgG3S) expressing human α1,4-galactosyltransferase (Gb3 synthase). High levels of Gb3 were observed in all major organs of the TgG3S mouse. A TgG3S (+/-)M(+/-)/KO mouse was prepared by cross-breeding the TgG3S and TgM/KO mice and the Gb3 content in the heart of the TgG3S(+/-)M(+/-)/KO mouse was 1.4 µg/mg protein, higher than in the TgM(+/-)/KO (<0.1 µg/mg protein). Treatment with an ASSC, 1-deoxygalactonojirimycin, caused a marked induction of α-Gal A activity and a concomitant reduction of the Gb3 content in the TgG3S(+/-) M(+/-)/KO mouse organs. These data indicated that the TgG3S(+/-) M(+/-)/KO mouse was suitable for studying ASSC therapy for Fabry disease, and that the TgG3S mouse would be useful for studying the effect of high Gb3 levels in mouse organs.

Biological analysis of gastrointestinal stromal tumors.

The biological behaviour of a gastrointestinal stromal tumor (GIST) cannot be easily predicted from preoperative clinical examination alone. As a result, there is little standardization in the surgical treatment of GIST. In this study, we analyzed the clinicopathology and immunohistochemistry of 20 cases of GIST to clarify factors associated with tumors showing malignant potential. Immunohistochemical analysis of KIT, CD34, vimentin, alpha-smooth muscle actin (SMA), s-100, p53, ki-67, bcl-2 and bax expression was performed on 20 surgically resected GIST. An apoptotic index (AI) was calculated for each sample using a TdT-mediated dUTP-biotin nick end-labeling method. With regard to bcl-2, t(14;18) translocations were also investigated using a polymerase chain reaction based method. Finally, the relationship between these biological results and clinicopathological data was analyzed. Of the 20 cases studied, two patients died due to lung or liver metastasis. All cases stained positive for vimentin, nine cases were positive for alpha-SMA and three cases positive for s-100. All cases were stained for both KIT and CD34, which tended to correlate with malignant potential. There was significant difference in frequency of bcl-2 overexpression (p<0.05) and trend in Ki-67 labeling index (p=0.098) between benign and malignant cases. However, with regard to bcl-2, no chromosomal t(14;18) translocations were detected in four analyzed cases. In GIST, overexpression of bcl-2 may play an important role in increasing malignant potential. Furthermore, Ki-67 L.I. and bcl-2 overexpression may be useful in predicting malignant potential, and therefore help to determine the surgical treatment, follow-up manner, and the necessity of adjuvant therapy.