CD4+ T cells infiltrating breast tumors exhibit altered expression
of T cell immune response genes in comparison with their counterparts
from the lymph node and blood
Equeter C, El Ouriaghli
F, Haibe-Kains B, Stamatopoulos B, André F, Lallemand
F, Filippov V, Larsimont D, Sotiriou C, Willard-Gallo K
We initiated a study to
understand the functional defects in T cells infiltrating breast tumors
by comparing purified CD4+ T cells from the primary tumor, axillary
lymph node and peripheral blood of individual patients with ER+ and ER−
invasive ductal breast carcinoma. CD4+ T cells were isolated after
tissue digestion with collagenase IV and the extracted RNA was analyzed
on Affymetrix Human GeneChip© Arrays. Unsupervised analysis revealed
that the greatest differences in gene expression were characteristic of
the tissue examined rather than the patient. Interestingly, the
profiles of gene expression for CD4+ T cells from patients compared
with age- and sex-matched controls were quite similar. However,
patient’s CD4+ T cells isolated from the tumor were strikingly
different from their blood. This comparative analysis revealed that the
T cell receptor (TCR/CD3) and IL-2 signaling pathways were
downregulated while the VEGF and TGFβ pathways were upregulated in the
tumor infiltrating T cells. These effects do not appear to be due to an
increased presence of regulatory CD4+ T cells since FOXP3 expression
was similar in cells isolated from the three tissues. Preliminary
real-time RT-PCR experiments confirm the downregulation of several
genes in the TCR/CD3 as well as in the IL-2 pathways. Flow cytometric
analysis revealed that TCR/CD3 surface proteins were also
downregulated, with the greatest difference observed between CD4+ T
cells from the tumor relative to the blood and to a lesser extent the
lymph node. Ongoing experiments have been designed to further our
understanding of changes in CD4+ T cell gene expression resulting from
their interactions with other cells present in the tumor
microenvironment.