The Things Aurora B inhibitor BI-1356 Pros Might Teach You

As an first assessment of cellular effects of exposure to CP466722, no adverse effects on cell viability had been observed in major and hTERT immortalized human diploid fibroblasts or within a wide variety of human tumor cell lines, even right after continuous exposure for 72 hours.

Disruption of ATM dependent phosphorylation events also as inhibition of ATM dependent p53 induction had been also observed in MCF 7 human breast cancer cells and major and immortalized diploid human fibroblasts. General, the response to IR in cells treated with CP466722 was similar to that noticed in cells lacking ATM. Because 1 long term objective is to characterize the potential Aurora B inhibitor of CP466722 to sensitize tumors to radiation or chemotherapeutic agents in murine models in vivo, it was important to know if CP466722 was effective at inhibiting Atm kinase in mouse cells. The ATM signaling pathway is conserved from human to mouse and ATM kinase activity can be monitored by analyzing similar downstream events. An exception is phosphorylation of Chk2 on threonine 68 which is difficult to detect in mouse cells.

While ATM is preferentially activated by DSBs and phosphorylates Chk2 on threonine 68, ATR is preferentially activated by stalled replication forks and phosphorylates serine 345 of Chk1. Though CP466722 BI-1356 did not affect ATR kinase activity in vitro, we examined the ability of the compound to affect ATR kinase activity in cells. hTERT immortalized human fibroblasts were treated for 1h with the replication inhibitor aphidicolin in the presence or absence of CP466722. ATR dependent phosphorylation of Chk1 was not inhibited by CP466722, even though ATM dependent phosphorylation of Chk2 was blocked in these cells. Failure to inhibit aphidicolin induced Chk1 phosphorylation in cells lacking ATM provided even more definitive evidence that CP466722 does not inhibit ATR kinase in cells.

Serum starvation resulted in an almost complete loss of AKT phosphorylation.