POSTCONFLUENT MULTILAYERED CELL-LINE CULTURES FOR SELECTIVE SCREENINGOF GEMCITABINE

The in vitro cytotoxicity of gemcitabine (dFdC) was tested in ovarian and colon cancer cell Lines grown as monolayers and three-dimensional multilayered cell cultures. In our model, dFdC showed slight selectivi ty in cytotoxicity against ovarian over colon cancer cells, when cell lines were grown as monolayers. However, when cell lines were grown as multilayers, this selectivity was accentuated: A2780 multilayers were 14 times less sensitive than monolayers, but the colon cancer cell li nes were more than 1000 times more resistant than their corresponding monolayers. The accumulation of the active metabolite, dFdCTP, after 2 4h exposure to 1 mu M dFdC varied between 1100 and 1900 pmol/10(6) cel ls in monolayers. This was 5 times lower in multilayers compared with monolayers of all four cell Lines, which can, in part, explain the low er sensitivity of the multilayers. In addition, it appears that the am ount of the active metabolite retained is more important than the amou nt accumulated initially, since the differences between the ovarian an d the colon cancer cell lines were more evident in retention experimen ts. Exposure to dFdC caused a 2-3-fold increase in the levels of sever al nucleotides, except for the CTP pools in the colon cancer lines, wh ich were reduced by 3-fold at the highest dFdC concentration (10 mu M) . The findings with the multilayer model are in better agreement with in vivo activity in ovarian cancer and colon cancer than those with th e monolayer system. This indicates the potential of the multilayer sys tem to be a better predictive model than the conventionally used monol ayer cultures. (C) 1998 Elsevier Science Ltd. All rights reserved.