Phosphorylated STAT3 (Tyr705) as a biomarker of response to pimozide treatment in triple-negative breast cancer
Sundee Dees, Laura Pontiggia, Jean-François Jasmin, Isabelle Le Mercier
Abstract
. Currently, there are no FDA-approved STAT3 inhibitors for TNBC. Although pimozide, a FDA-approved antipsychotic drug, has been attributed a role as a STAT3 inhibitor in several cancers, its role on this pathway remains unexplored in TNBC. As a "one size fits all" approach cannot be applied to TNBC therapies due to the heterogeneous nature of this aggressive cancer, we hypothesized that STAT3 could be a novel biomarker of response to guide pimozide therapy. Using human cell lines representative of four TNBC subtypes (basal-like 1, basal-like 2, mesenchymal-like, mesenchymal stem-like), our current report demonstrates that pimozide significantly reduced their invasion and migration, an effect that was predicted by STAT3 phosphorylation on tyrosine residue 705 (Tyr705). Mechanistically, phosphorylated STAT3 (Tyr705) inhibition resulting from pimozide treatment caused a downregulation of downstream transcriptional targets such as matrix metalloproteinase-9 (MMP-9) and vimentin, both implicated in invasion and migration. The identification of biomarkers of response to TNBC treatments is an active area of research in the field of precision medicine and our results propose phosphorylated STAT3 (Tyr705) as a novel biomarker to guide pimozide treatment as an inhibitor of invasion and migration.