Sp) Octyl 8 chloroadenosine 3′5′cyclophosphate (OCC), a newly synthesized 8 Cl c AMP derivative, strongly induced inhibition and differentiation in human leukemia HL 60 cells. In flow cytometry, OCC brought about a block at the G1 phase of HL 60 cell cycle. OCC inhibited strongly the synthesis of DNA without affecting the synthesis of RNA and protein in HL 60 cells and also activated the c AMP dependent protein kinase in the cytosol of HL 60 cells. 8 Chloroadenosine is the active metabolite of OCC and inhibited significantly the growth of tumour in vitro and in vivo tests. 8 Chloroadenosine can induce differentiation of gastric mucoid adenocarcinoma cell line MGc80 3 and induce apoptosis in the MOLT 4 cells. The mechanism of the antitumour effects of 8 chloroadenosine was discussed.
