Roscovitine

Roscovitine (Seliciclib or CYC202) is a cyclin-dependent kinase (CDK) inhibitor that preferentially inhibits multiple enzyme targets including CDK2, CDK7 and CDK9, which alter the growth phase or state within the cell cycle of treated cells. Cyclin-dependent kinases (cdk) play an essential role in the intracellular control of the cell division cycle (cdc). Seliciclib has been shown to inhibit RNA polymerase II-dependent transcription and down-regulation of the protein MCL1. Roscovitine inhibits in vitro M-phase-promoting factor activity and in vitro DNA synthesis in Xenopus egg extracts. It blocks progesterone-induced oocyte maturation of Xenopus oocytes and in vivo phosphorylation of the elongation factor eEF-1. Roscovitine inhibits the proliferation of mammalian cell lines with an average IC50 of 16 microM. At 20 microM, Roscovitine induced apoptosis in 21 of 28 B-CLL samples and was equally effective in zap-70-positive or -negative samples. Caspase-3 was cleaved in B-CLL cells exposed to Roscovitine and the pancaspase inhibitor z.VAD.fmk-blocked Roscovitine-induced apoptosis. Roscovitine induced a block in G1 earlier than that induced by aphidicolin. S-phase synchronized cells treated with roscovitine were arrested at a 4C DNA content at the G2/ M transition. Finally, cells in metaphase were insensitive to roscovitine. The purified CDK/cyclin kinase activities of late G1 and early M arrested cells were inhibited in vitro by roscovitine.