Prostaglandin E2 regulates B cell proliferation through a candidate tumor suppressor, Ptger4

ABSTRACT: Recognition of foreign antigens by B cell receptor (BCR) on mature B cells leads to their clonal expansion, which is critically important for the effective host defence of the organism. However, excessive antigenic responses or reaction of B cells against body’s own components frequently lead to diverse immune diseases, such as B-cell lymphoma or autoimmunity, that often affect humans. Identification of genes that restrain uncontrolled proliferation of B cells is therefore an important goal towards understanding the origin of such diseases. Here we identify Ptger4 as a negative feedback regulator of B-cell proliferation in response to BCR triggering, and show that its encoded EP4 receptor is a principal molecule conveying the growth-suppressive effect of prostaglandin E2 (PGE2). In controlled in vitro assays, Ptger4-/- B cells showed augmented proliferative response and increased expression of activating genes upon BCR stimulation. Stable knock-down of Ptger4 in B-cell lymphoma markedly accelerated tumour spread in mice, while Ptger4 overexpression yielded significant protection. Lack of Ptger4 rendered mouse B cells completely resistant to proliferation arrest signalled by PGE2, and we find by transcriptional profiling that intrinsic activity of Ptger4 and PGE2-EP4 signalling target a similar set of activating genes. We further show that Ptger4 inhibits mouse B-cell activation in vivo and find it significantly downregulated in human B-cell lymphoma. Our results demonstrate that Ptger4 functions in B cells as a candidate tumour suppressor whose activity is regulated by the presence of PGE2 in the microenvironment. These findings suggest that targeting EP4 receptor for prostaglandin may present a novel strategy for treatment of B-cell diseases. Keywords: time course, cell type comparison, compound treatment design, microarray experiment record B cells were extracted from spleen of Ptger4+/+ and Ptger4-/- mice, and incubated in vitro for the indicated period with or without anti-IgM (Fab')2 antibody fragments and co-treated with or without PGE2. Total RNA was extracted, amplified, labelled with Cy3 or Cy5, and hybridized to mouse 24k oligo-arrays using a dye-swap strategy.

ORGANISM(S): Mus musculus

SUBMITTER: Olivier ALIBERT 

PROVIDER: E-GEOD-9847 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress