Arsenic trioxide inhibits human t cell-lymphotropic virus-1-induced syncytiums by down-regulating gp46.

Adult T-cell leukemia (ATL) is a severe chemotherapy-resistant malignancy associated with prolonged infection by the human T cell-lymphotropic virus 1 (HTLV-1). One approach to prevent the onset of ATL is to inhibit the growth/transmission of HTLV-1 infected cells using arsenic trioxide (As(2)O(3)). However, there are no reports on the transmission inhibitory effect of As(2)O(3). In this study, we reveal that As(2)O(3) exerts an inhibitory effect on syncytium formation between HTLV-1 infected MT-2 and HeLa cells. In addition, Western blot analysis revealed that the HTLV-1 derived envelope protein gp46 was down regulated by As(2)O(3) treatment, suggesting that As(2)O(3) may inhibit HTLV-1 virus transmission via down-regulation of gp46. These results suggest that As(2)O(3) may be a promising drug to treat refractory HTLV-1-related diseases.