At higher concentra tions, a change in the cell morphology

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The combination index analysis showed synergistic cyto toxic effects when two drugs were combined at relatively higher concentrations. Next, whether perifosine enhances the effect of SNS 032 in long term colony formation assay was also examined. We observed that, under the conditions when SNS 032 or perifosine alone had moderate inhibition effect Ivacaftor 構造 of colony formation of leukemic cell lines the combination therapy almost com pletely suppressed the colony forming ability of these leukemic cells, Similar results were also found in primary blasts obtained from 2 patients with AML, To further delineate the effect of combination treatment on growth signaling, we examined the effect of SNS 032, perifosine, and combin ation on the activiation of caspase pathway, phosphorylation of mTOR and downstream targets, as well as expression of phosphor ERK1 2.

As shown in Figure 7D, we found that al though SNS 032 and perifosine alone had little effect on caspase 3 and PRAP, the two together were highly effective, suggesting that perifosine can enhance SNS 032 induced apoptosis. LBH589 代理店 Several studies have shown that perifosine inhibits activation of Akt in cancer cells, Consistent with these reports, perifosine significantly inhibited the level of phosphorylated Akt in KG 1 and NB4 cells and consequently decreased the level of phosphorylated mTOR, which represent the activity of mTORC1, but not that of phosphorylated mTOR, Whereas, phosphorylated mTOR levels declined in KG 1 and NB4 cells at the low concentrations of 60 and 80 nM of SNS 032, respectively.

Importantly, combined SNS 032 and perifosine therapy resulted in almost complete elimination of phosphorylated Akt and activity of mTORC1. Consequently, it also significantly attenuated 4E BP1 phosphorylation at all tested sites and phosphorylated p70S6K, both of which are direct target of mTORC1. Together, LY2109761 availability this combin ation treatment is likely to have significant benefit to AML patients as it can synergistically inhibit activity of mTORC1 and Akt in leukemic cells. Discussion CDK inhibitors are gaining success in the clinic as antitumor agents for cancers including hematologic ma lignancies, SNS 032 is a potent CDK inhibitor, which targets CDK2, CDK7, and CDK9, the CDKs that regulate the initiation and elongation of transcription by phosphorylating Ser2 and Ser5 of RNA Pol II, respect ively.

These biologic effects are attributed to the inhibi tory activity against CLL and MCL cells, which was also demonstrated in AML cells, This study investigated the actions of SNS 032 in AML cells. Our results showed that SNS 032 was active against majority of the tested AML cell lines and primary leukemic cells. However, its mechanisms of action seem to be dependent on the molecular context of the disease. We found that in addition to the typical inhibitory effect on phosphorylation of RNA pol II, SNS 032 caused reduc tion of activity of mTORC1 and mTORC2, as evidenced by dephosphorylation of mTOR on Ser2448 and Ser2481, without strongly inhibiting PI3K, ERK MAPK, and STAT3 5. Consistent with these results, SNS 032 treatment elicited potent suppression of phosphorylation 4E BP1 and p70S6K, the downstream targets of mTORC1, in AML cells and also reduced phosphor Akt on Ser473, a substrate of mTORC2.