Scientific Reports (Jul 2017)

Reduced expression of the murine HLA-G homolog Qa-2 is associated with malignancy, epithelial-mesenchymal transition and stemness in breast cancer cells

  • Istéfani L. da Silva,
  • Lucía Montero-Montero,
  • Ester Martín-Villar,
  • Jorge Martin-Pérez,
  • Bruno Sainz,
  • Jaime Renart,
  • Renata Toscano Simões,
  • Émerson Soares Veloso,
  • Cláudia Salviano Teixeira,
  • Mônica C. de Oliveira,
  • Enio Ferreira,
  • Miguel Quintanilla

DOI
https://doi.org/10.1038/s41598-017-06528-x
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 11

Abstract

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Abstract Qa-2 is believed to mediate a protective immune response against cancer; however, little is known about the role of Qa-2 in tumorigenesis. Here, we used 4T1 breast cancer cells to study the involvement of Qa-2 in tumor progression in a syngeneic host. Qa-2 expression was reduced during in vivo tumor growth and in cell lines derived from 4T1-induced tumors. Tumor-derived cells elicited an epithelial-mesenchymal transition associated with upregulation of Zeb1 and Twist1/2 and enhanced tumor initiating and invasive capacities. Furthermore, these cells showed increased stem characteristics, as demonstrated by upregulation of Hes1, Sox2 and Oct3/4, and enrichment of CD44high/CD24median/low cells. Remarkably, Qa-2 cell-surface expression was excluded from the CD44high/CD24median/low subpopulation. Tumor-derived cells showed increased Src activity, and treatment of these cells with the Src kinase inhibitor PP2 enhanced Qa-2 but reduced Sox2 and CD44high/CD24median/low expression levels, suggesting that Src signaling, while positively associated with stemness, negatively regulates Qa-2 expression in breast cancer. Finally, overexpression of the Qa-2 family member Q7 on the cell surface slowed down in vivo tumor growth and reduced the metastatic potential of 4T1 cells. These results suggest an anti-malignant role for Qa-2 in breast cancer development, which appears to be absent from cancer stem cells.