(A) Scheme of a yeast-based screen for drug-resistant mutations in mTOR kinase
domain. mTOR kinase domain is amplified by error-prone PCR to generate
randomized mutations, which is then recombined in frame into the TOR2-mTOR
plasmid by gap-repair in tor2-dg cells, and is selected on
SC-leucine minus plates. Replica plating is then made onto SC-leucine plates
containing DMSO or mTOR kinase inhibitor for selection of drug resistant
clones.
(B) tor2-dg cells expressing WT or mutant TOR2-mTOR were
serially diluted by 10-fold and assayed for sensitivity to different mTOR kinase
inhibitors in the presence of amphotericin B. Vector and TOR2 were used as
controls. Drug resistant assay was performed at 37°C in the presence of
amphotericin B (except OSI-027).
(C) Systematic mutational analysis of L2185 on drug resistance.
tor2-dg cells expressing WT or mutant TOR2-mTOR carrying
all possible mutations at L2185 were serially diluted by 10-fold and tested for
sensitivity to different mTOR kinase inhibitors at 37°C. AZD8055, BEZ235,
INK128, PF-04691502 and PKI-587 were supplemented with amphotericin B.