Tumor Cell-Derived Periostin Regulates Cytokines That Maintain Breast Cancer Stem Cells

Basal-like breast cancer (BLBC) cells share phenotypic similarities with cancer stem cells (CSCs) but the underlying molecular basis for this connection remains elusive. We hypothesized that BLBC cells are able to establish a niche permissive to the maintenance of CSCs and found that tumor cell-derived periostin (POSTN), a component of the extracellular matrix, as well as a corresponding cognate receptor, integrin αvβ3, are highly expressed in a subset of BLBC cell lines as well as in cancer stem cell-enriched populations. Furthermore, we demonstrated that an intact periostin-integrin β3 signaling axis is required for the maintenance of breast CSCs. POSTN activates the ERK signaling pathway and regulates NF-κB-mediated transcription of key cytokines, namely IL6 and IL8, which in turn mediate downstream activation of STAT3. In summary, these findings suggest that BLBC cells have an innate ability to establish a microenvironmental niche supportive of CSCs. RNA was isolated from three biological replicates of the indicated SUM159 cell lines. SUM159 shGFP cells express a control shRNA plasmid directed at GFP while the two other lines carry shRNA plasmids directed at POSTN or ITGB3.