Novel Insights into YB-1 Signaling and Cell Death Decisions

SIMPLE SUMMARY: Signals that determine cell survival or death are essential for maintaining tissue homeostasis. Cell death promotes the removal of unwanted cells; however, a failure of cells to die or cells dying when they should not can exacerbate inflammation, and the former is a causative factor in cancerous diseases. YB-1 plays critical roles in cell proliferation and differentiation, stress responses, and tumorigenesis. In this review, we have summarized recent insights into the role of YB-1 in signaling cell survival and apoptosis. ABSTRACT: YB-1 belongs to the evolutionarily conserved cold-shock domain protein family of RNA binding proteins. YB-1 is a well-known transcriptional and translational regulator, involved in cell cycle progression, DNA damage repair, RNA splicing, and stress responses. Cell stress occurs in many forms, e.g., radiation, hyperthermia, lipopolysaccharide (LPS) produced by bacteria, and interferons released in response to viral infection. Binding of the latter factors to their receptors induces kinase activation, which results in the phosphorylation of YB-1. These pathways also activate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a well-known transcription factor. NF-κB is upregulated following cellular stress and orchestrates inflammatory responses, cell proliferation, and differentiation. Inflammation and cancer are known to share common mechanisms, such as the recruitment of infiltrating macrophages and development of an inflammatory microenvironment. Several recent papers elaborate the role of YB-1 in activating NF-κB and signaling cell survival. Depleting YB-1 may tip the balance from survival to enhanced apoptosis. Therefore, strategies that target YB-1 might be a viable therapeutic option to treat inflammatory diseases and improve tumor therapy.