Metastatic estrogen receptor (ER)-expressing breast cancer (BC) occurs after prolongedpatient treatment with endocrine therapy (ET) (e.g., aromatase inhibitors—AI; 4OHtamoxifen—4OH-Tam). Often these metastatic BCs express a mutated ER variant (e.g., Y537S),which is transcriptionally hyperactive, sustains uncontrolled proliferation, and renders tumor cellsinsensitive to ET drugs. Therefore, new molecules blocking hyperactive Y537S ER mutation transcriptionalactivity are requested. Here we generated an MCF-7 cell line expressing the Y537SER mutation stably expressing an estrogen-responsive element (ERE) promoter, which activitycan be monitored in living cells. Characterization of this cell line shows both hyperactive basaltranscriptional activity with respect to normal MCF-7 cells, which stably express the same ERE-basedpromoter and a decreased effect of selective ER downregulators (SERDs) in reducing Y537S ERmutant transcriptional activity with respect to wild type ER transcriptional activity. Kinetic profilesof Y537S ER mutant-based transcription produced by both drugs inducing receptor degradationand siRNA-mediated depletion of specific proteins (e.g., FOXA1 and caveolin1) reveals biphasicdynamics of the inhibition of the receptor-regulated transcriptional effects. Overall, we report a newmodel where to study the behavior of the Y537S ER mutant that can be used for the identification ofnew targets and pathways regulating the Y537S ER transcriptional activity.
Real-Time Challenging of ER Y537S Mutant Transcriptional Activity in Living Cells
Cipolletti M;
2021-01-01
Abstract
Metastatic estrogen receptor (ER)-expressing breast cancer (BC) occurs after prolongedpatient treatment with endocrine therapy (ET) (e.g., aromatase inhibitors—AI; 4OHtamoxifen—4OH-Tam). Often these metastatic BCs express a mutated ER variant (e.g., Y537S),which is transcriptionally hyperactive, sustains uncontrolled proliferation, and renders tumor cellsinsensitive to ET drugs. Therefore, new molecules blocking hyperactive Y537S ER mutation transcriptionalactivity are requested. Here we generated an MCF-7 cell line expressing the Y537SER mutation stably expressing an estrogen-responsive element (ERE) promoter, which activitycan be monitored in living cells. Characterization of this cell line shows both hyperactive basaltranscriptional activity with respect to normal MCF-7 cells, which stably express the same ERE-basedpromoter and a decreased effect of selective ER downregulators (SERDs) in reducing Y537S ERmutant transcriptional activity with respect to wild type ER transcriptional activity. Kinetic profilesof Y537S ER mutant-based transcription produced by both drugs inducing receptor degradationand siRNA-mediated depletion of specific proteins (e.g., FOXA1 and caveolin1) reveals biphasicdynamics of the inhibition of the receptor-regulated transcriptional effects. Overall, we report a newmodel where to study the behavior of the Y537S ER mutant that can be used for the identification ofnew targets and pathways regulating the Y537S ER transcriptional activity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
