Gene expression analysis of imatinib-resistant GIST

To reveal mechanisms for acquired imatinib resistance in gastrointestinal stromal tumor (GIST), we have analyzed several cell lines with resistance to imatinib. The parental cell line, T1, was cultured exposed to imatinib, doses of which were increased in a stepwise manner where we selected survived cells until normal cell growth resumed. Thus, we independently established imatinib-resistant GIST cell lines, which exhibited more than 500 times IC50 values (over 10 μM) for imatinib compared to the parental line. R2, RA2, R8, and R9 are fully resistant cell lines. T117 was exposed only for 7 weeks.