Five cell lines showed markedly larger IC50 values, KCL 22, MHH TALL1, NALM 1, SD 1, and SUP B15. These cell lines were inherently
selelck kinase inhibitor resistant to imatinib according to the results of proliferation and apoptosis assays, as they had not been preincubated with the TKI. BCR ABL1 mutations, BCR ABL1 expression, imatinib transporters Point mutations within the kinase domain of BCR ABL1 will be the most important result in of imatinib resistance inside the chronic phase of CML. Despite the fact that second generation BCR ABL1 inhibitors are effective in most BCR ABL1 mutated cases, all 5 imatinib insensitive cell lines identified here were also resistant to nilotinib suggesting that resistance may possibly not be triggered by BCR ABL1 mutations. In accordance with this notion, genomic AZD6482,AZD8330,AZD8931 sequencing showed no sequence altera tions within the kinase domain in the resistant cell lines. The DNA binding protein Ikaros is a major regulator of lymphoid development. Deletion of Ikaros is located in the majority of BCR ABL1 good ALL and of CML in progression to lymphoid blast crisis. Public genomic array data indicate hemizygous loss of your 7p12 region in cell line NALM 1, which includes IKZF1 along with the neighbouring gene Dopa decarboxylase sanger. ac. ukcgi bingeneticsCGP 10kCGHviewer. cgi chr 7 dna NALM 1. Genomic PCR analysis confirmed loss of IKZF1 in this cell line, but not in cell lines SD 1, SUP B15 and MHH TALL 1. Even so, the majority of Ph ALL with IKZF1 aberrations do not show deletion on the whole gene, but as an alternative intragenic loss of many IKZF1 exons, top for the expression of mRNA variants that mimic normal splice variants. A recent publi cation correlates expression in the Ikaros variant Ik6 with high BCR ABL1 mRNA levels and imatinib resistance in Ph ALL. We couldn't confirm this correlation among Ph ALL and CML cell lines, Ik6 was expressed in 219 BCR ABL1 good cell lines, a single becoming imatinib sensitive and a single resistant. Neither
Osteosarcoma cell line SUP B15 nor most other TKI resistant cell AZD6482,AZD8330,AZD8931 lines showed particularly high BCR ABL1 expression levels in accordance with quantita tive RT PCR analysis. The only exception was cell line KCL 22 with about 2 fold greater BCR ABL1 expression levels, both at the mRNA as well as the protein level. Even though supporting the notion that a causative correlation may exist in between the higher expression of your mutated kinase and imatinib resistance for cell line KCL 22, these final results also showed that in 45 cell AZD6482,AZD8330,AZD8931 lines TKI resistance was not the conse quence of BCR ABL1 overexpression. Therefore, neither BCR ABL1 mutations nor overexpres sion from the kinase were the general trigger AZD6482,AZD8330,AZD8931 for imatinib resistance in these cell lines. Consequently, it appeared unlikely that imatinib resistance was caused by deregulated
selleck chemicals transport proteins. Finally, the obtaining that both imatinib and nilotinib AZD6482,AZD8330,AZD8931 induced dephosphorylation of signal transducer and activator of transcription 5 inside the TKI resistant cell line SUP B15 as shown in Figure 2 additional excludes resis tance being due to low intracellular drug levels. Both drugs were transported into the cells which responded by dephosphorylating STAT5 although AZD6482,AZD8330,AZD8931 retaining viability.
