[A study of the effect of anti-tumor agents combined with caffeine on established lines of human osteosarcoma cells and primary cultured human sarcoma cells by clonogenic assay].

A study on the effect of anti-tumor agents combined with caffeine on sarcoma cells was carried out by clonogenic assay. The materials used were an established line of human osteosarcoma cells (OST strain) and twelve surgically resected or biopsied specimens. Caffeine showed a marked synergistic effect on sarcoma cells with the DNA-damaging agents, ADR, CDDP, CPM and MMC in terms of colony inhibition. In particular, 0.2 micrograms/ml CDDP with 2 mM caffeine showed a considerable synergistic effect on human sarcoma cells. Among the 12 cases, more than 50% colony inhibition was observed in 7 cases which were treated with this combination of CDDP with caffeine. Furthermore, a combination of 0.02 micrograms/ml CDDP (1/100 of peak plasma concentration) with 2 mM caffeine also showed more than 50% colony inhibition. Therefore, we assumed that caffeine was able to reduce the necessary dose of anti-tumor agent in some way. We stress that caffeine seems to be a very useful synergistic drug for causing lethality in sarcoma cells in combination with various DNA-damaging agents which are not effective on sarcoma cells.