CD7 promotes extramedullary involvement of the B-cell acute lymphoblastic leukemia line Tanoue by enhancing integrin β2-dependent cell adhesiveness

Int J Oncol. 2014 Sep;45(3):1073-81. doi: 10.3892/ijo.2014.2492. Epub 2014 Jun 11.

Abstract

Extramedullary involvement (EMI) is a factor that defines prognosis of acute lymphoblastic leukemia; however, the molecular mechanism(s) remain elusive. Here, we show that CD7 promotes EMI of the human B-cell acute lymphoblastic leukemia cell line Tanoue. The Tanoue cell line expressing firefly luciferase, Luc-Tanoue, was transplanted into non-obese diabetic/severe combined immunodeficient mice, and cells infiltrated into the brain were cultured ex vivo. This process was repeated 4 times to obtain the highly invasive line Luc-Tanoue-F4. Comparison of the global gene expression signatures of Luc-Tanoue-F4 and Luc-Tanoue indicated that the CD7 gene showed the largest increase in expression among EMI-related genes in Luc-Tanoue-F4 cells. Overexpression of CD7 in Tanoue enhanced cell invasiveness. Among cell migration, proliferation, adhesion and protease activity, only cell adhesiveness showed enhancement in Luc-Tanoue-F4. Expression of the intracellular domain, but not the extracellular domain, of CD7 enhanced cell adhesiveness. Luc-Tanoue-F4 showed a higher level of integrin β2 expression; overexpression of CD7 induced the expression of integrin β2 in Luc-Tanoue. These results show that CD7 induces integrin β2 and enhances cell adhesiveness and invasiveness in Tanoue cells. This study highlights the role of the CD7/integrin β2 axis as a critical pathway in the process of EMI of human B-cell acute lymphoblastic leukemia.

MeSH terms

  • Animals
  • CD18 Antigens / metabolism*
  • Cell Adhesion
  • Cell Line, Tumor
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Mice
  • Mice, Inbred NOD
  • Neoplasm Invasiveness / genetics*
  • Neoplasms, Experimental
  • Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / metabolism*
  • Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / pathology*

Substances

  • CD18 Antigens