Oncoprotein SET dynamically regulates cellular stress response through nucleocytoplasmic transport in breast cancer.

ABSTRACT

SETß is the predominant isoform of oncoprotein SE translocation (SET) in various breast cancer cell lines. Interactome-transcriptome analysis has shown that SETß is intimately associated with cellular stress response. Among various exogenous stimuli, formaldehyde (FA) causes distinct biological effects in a dose-dependent manner. In response to FA at different concentrations, SET dynamically shuttles between the nucleus and cytoplasm, performing diverse biofunctions to restore homeostasis. At a low concentration, FA acts as an epidermal growth factor (EGF) and activates the HER2 receptor and downstream signaling pathways in HER2+ breast cancer cells, resulting in enhanced cell proliferation. Nucleocytoplasmic transport of SETß is controlled by the PI3K/PKCα/CK2α axis and depletion or blockade of the transport of SETß suppresses EGF-induced activation of AKT and ERK. SETß also inhibits not only stress-induced activation of p38 MAPK signaling pathway, but also assembly of stress granules by hindering formation of the G3BP1-RNA complex. Our findings suggest that SET functions as an important regulator which modulates cellular stress signaling pathways dynamically.