HKI 272 th showed that these naturally Smoothened Pathway overexpress ERBB2 NSCLC cells sensitive to a degree comparable with the line H 1781 ERBB2 described mutant cells that were previously too sensitive of us have HKI 272, w While the cell line with KRAS mutations A549 was resistant HKI 272nd In accordance with the Ver published shall result, Calu 3 cells were widerstandsf less Be treated as hig to erlotinib H 1781 cells, the IC 50 for erlotinib was about 10 times but h Ago for 272 as HKI. Biochemical analysis showed that pharmacodynamic treatment of both H 1781 and Calu 3 cells with 272 to HKI inhibition of receptor phosphorylation and inhibition of phosphoinositide 3-kinase and mitogen-activated protein kinase canals le leads at nanomolar concentrations. In a direct comparison of the biochemical reaction between the ERBB2 and EGFR mutant Ba/F3 cells with Calu 3 and H 1781 cells, we found that the absolute values are found in the tests IC50 growth inhibition, the F Ability of the drug in order to reflectthe target effect. The absolute difference in IC50 values between GM and Ba/F3 naturally occurring mutant cancer cell lines may be due to Changes in the intracellular Ren drug metabolism and the biochemical IC 50 values were Similar to the values determined in assays of inhibition of growth. These differences are nnten k Also in H 3255-cells was observed that the mutation of the EGFR L858R when its receiver Accessibility for EGFR inhibitor erlotinib with the L858R mutant Ba/F3 cells was compared. It is important to both H and 3255 L858R mutant Ba/F3 cells are also models EGFRmutant and erlotinib-sensitive lung tumors observed. Thus, although the differences in absolute IC 50 values in natural cancer cell lines and Ba/F3 cells expressing the same genetic L can Observed sion, they usually show anything similar Ph Genotypes in the drug Sen treatment. In summary, we have shown that the h Most frequent NSCLC derived ERBB2 mutants and the wild-type ErbB2 overexpression induces oncogenic transformation in a mouse model of cell transformation. The transformation was accompanied by constitutive autophosphorylation of mutant transgenic and wild-type ERBB2. Closing Lich, although the resulting cells were relatively resistant to reversible EGFR TKIs erlotinib, they have excellent sensitivity t the irreversible inhibitor with dual specificity t EGFR/ERBB2 kinase, HKI shown 272nd Additionally Tzlich to somatic mutations ERBB2 ERBB2 gene amplification has reported recently in a proportion of non-small cell lung cancer. In line with these observations revealed a vorl INDICATIVE analysis of gene copy number using SNP arrays to Gain Ren rkung of ERBB2 in a case of 95 prime NSCLC tumors. Taken together, k Can our results provide a rationale for the use of dual EGFR/ERBB2 irreversible inhibitors, such as HKI deliver 272 verst, in patients with ErbB2 mutant or ERBB2 RKT lung tumors. Materials and Methods for generating mutants Ba/F3 cells ERBB2 ERBB2 cDNA was subcloned into pBabe hygro. The h Ufigsten NSCLC mutant derivatives were prepared in the retroviral construct via site-specific mutagenesis and viral supernatant, introduced as described. Murine Ba/F3 cells were fa Is Stable transduced with retroviruses and IL-3 was withdrawn. A drug Se treatment, the cells seeded in 96-well plates t and.