Diverse effects of indolocarbazole compounds on the cell cycle progression of ras-transformed rat fibroblast cells.

Indolocarbazole compounds have been reported to exert antitumor activity against human and murine tumor cell lines in vitro and/or in v/vo1~13).These compoundsare thought to be divided into two major groups, i.e. protein kinase inhibitors and topoisomerase inhibitors7).The former includes natural compounds such as staurosporine1}, K-252a2) and UCN-013~5) as well as chemically synthesized derivatives of the natural compounds2'6'1 1}.The latter includes natural compounds such as rebeccamycin8), AT24339) and several derivatives of the natural compounds which did not exert the apparent inhibitory activities against protein kinases7'10~12).Recent studies showed that staurosporine and K-252a exhibited a unique effect on the cell cycle distribution of mammalian cells13~17).At lower