Pirarubicin

Pirarubicin is rapidly taken up by M5076 cells and the intracellular concentration of pirarubicin reaches more than 2.5-fold that of doxorubicin. Pirarubicin is more effective than doxorubicin in terms of the 50% cell growth-inhibitory concentration in vitro. ^[1] Pirarubicin causes G0/G1 cell cycle arrest in MG-63 cells. Pirarubicin suppresses the expression of PCNA, cyclin D1, cyclin E and Bcl-2, and increases Bax expression in MG-63 cells. ^[2] Pirarubicin markedly relaxes contractions induced by noradrenaline (0.1 μM) in the aorta with endothelium, but not in that without endothelium. Pirarubicin-induced relaxation is inhibited by methylene blue (5 μM), hydroquinone (100 μM), phenidone (50 μM), haemoglobin (1 μM) and p-bromophenacyl bromide (50 μM), but not by indomethacin (25 μM). ^[3] Pirarubicin is approximately 2-5 times more potent than Adriamycin in SKUT1B, HEC1A, and BG1 cell lines. Pirarubicin also displays a reverse dose-response pattern of G2 block so that at high dose, cell cycle kinetics would mirror those of untreated controls. ^[4]

Pirarubicin reduces the tumor weight to 60% of the control level in M5076 solid tumor-bearing mice, although doxorubicin has no effect. ^[1] Pirarubicin and Epirubicin are effective against V x 2 tumor when injected via the hepatic intra-arterial (h.i.a.) route, the activity of Pirarubicin is stronger than that of Epirubicin. ^[5]