The function of the full length p53 protein in the Calu 6 c

[jy9202]

Our results show that SNS 032 significantly inhibits cell proliferation and induces apoptosis in AML cells. However, some of leukemic cells are resistant to the drug induced cell death. Furthermore, we show, for the first time, that SNS 032 suppresses the levels of mTOR expression and phosphor mTOR on Ser2448 and Ser2481. Additionally, treatment of human AML cells JAK 阻害剤 with SNS 032 in combin ation with Akt inhibitor perifosine causes enhanced cell death. This synergistic cytotoxic effect most likely results from elimination of Akt activation. The findings of the present study provide a rationale for combining SNS 032 with perifosine for the treatment of AML. Results SNS 032 mediated leukemia cell killing effect It has been shown that AML and CML cells are sensitive to SNS 032, We first examined the effect of SNS 032 on the viability of cultured AML cell lines.

As shown in Figure 1A, the doses that inhibited 50% proliferation at 24 h on cell proliferation buy LDE225 in a panel of 7 AML cell lines ranged from 71. 7 402 nM, with the panel including subtypes M2, M3, M5, and M6 according to the French American British classifi cation. The IC50 in CML K562 cells was 224. 3 nM. HEL cells, however, were found to be resistant with IC50 3000 nM. Consistent with these results, colony forma tion assay showed that a significant reduction in clonogenic ability at 50 and 100 nM and a complete ces sation of colony formation at 200 nM in HL 60, THP 1, U937, KG 1, and NB4 cells, but not in Kasumi 1 and K562 cells.

HEL cells were resistant to SNS 032 in respect to inhibiting colony forming, We next evaluated the effects of SNS 032 on the cellular proliferation of primary leukemic cells. The characteristics of 47 patients are detailed in Table 1. The majority of primary AML samples was very sensitive to the drug, with mean IC50 values for LY2109761 ic50 the different FAB types ranging between 136. 2 nM and 186. 7 nM, There was no significant difference between the response to SNS 032 and the characteristics of AML patients, How ever, a small fraction of the specimens was rela tively resistant to SNS 032 mediated cell death, Also, a significant decrease in the number of colony formation was observed in the primary blasts obtained from 4 patients with newly diagnostic AML, but not in the bone marrow cells from healthy volunteers, SNS 032 induced apoptosis and inhibited not only phosphorylation of RNA Pol II but also phosphorylation of mTOR and its downstream targets Previous studies showed that induction of apoptosis is a key action for SNS 032 induced cell death in AML and CML, We therefore evaluated the effect of SNS 032 on apoptosis of AML cell lines.

Cells were treated with increas ing doses of the drug for 24 h, and then apoptotic cells were determined by annexin V FITC. The 50% effective concen tration of KG 1 and HL 60 cell lines was 192. 2 and 194. 8 nM, respectively. In contrast, HEL cells were resistant to SNS 032 induced apoptosis. There was little cell death at 24 h after SNS 032 treatment, even at concentration of 200 nM, To examine the cell cycle effects, HL 60 cells were cultured with SNS 032 or Rapamycin, respect ively, and cell cycle analysis was performed.