Significant differences in the retention of the borocaptate monomer (BSH) and dimer (BSSB) in malignant cells

The B-10 enriched form of Na2B12H11SH (BSH) is used in a binary cancer radi ation treatment, known as boron neutron capture therapy (BNCT). The BSH ani on can also form a dimer, [B24H22S2](4-) (BSSB), previously used in animal model studies. It is demonstrated here that the retention of BSSB in mouse M2R melanoma and rat C6 glioma cells is significantly longer than that of t he monomer BSH. The washout of the BNCT agents from cultured cells was foll owed using B-11 nuclear magnetic resonance spectroscopy. One hour after swi tching to boron-free culture medium, the relative amount of BSSB retained i n M2R cells was at least about six times higher than that of BSH The initia l washout rate (over the first similar to4 h) of BSSB was 4 x 10(-3) min(-1 ) (t(1/2), similar to3 h) for M2R cells, and of the same order of magnitude for glioma cells. (C) 2001 Elsevier Science Ireland Ltd. All rights reserv ed.