Epithelial-mesenchymal interaction protects normal colonocytes from 4-HNE-induced phenotypic transformation
Abstract
Introduction
Recent studies have shown that epithelial-stromal interactions could play a role in the development
of colorectal cancer. Here, we investigated the role of fibroblasts in the transformation
of normal colonocytes induced by 4-HNE.
Methods
Normal Co colonocytes and nF fibroblasts from the same mouse colon were exposed, in
monoculture (m) or coculture (c), to 4-HNE (5 μM) twice weekly for 3 weeks. Gene expression
was then analysed and the ability of Co colonocytes to grow in anchorage-independent
conditions was tested in soft agar. Fibroblasts previously treated or not with 4-HNE were
also seeded in culture inserts positioned above the agar layers to allow paracrine exchanges
with colonocytes.
Results
First, 60% of the genes studied were modulated by coculture in Co colonocytes, with
notably increased expression of BMP receptors. Furthermore, while 4-HNE increased the
ability of monoculture-treated Co colonocytes to form colonies, this effect was not
observed in coculture-treated Co colonocytes. Adding a selective BMPR1 inhibitor during
the treatment phase abolished the protective effect of coculture. Conversely, addition of a
BMP4 agonist to the medium of monoculture-treated Co colonocytes prevented phenotypic
transformation by 4-HNE. Second, the presence of nF(m)-HNE fibroblasts during
the soft agar assay increased the number and size of Co(m) colonocyte colonies, regardless
of whether these cells had been previously treated with 4-HNE in monoculture. For
soft agar assays performed with nF(c) and Co(c) cells initially treated in coculture, only
the reassociation between Co(c)-HNE and nF(c)-HNE resulted in a small increase in the
number of colonies.
Conclusions
During the exposure phase, the epithelial-mesenchymal interaction protected colonocytes
from 4-HNE-induced phenotypic transformation via activation of the BMP pathway. This
intercellular dialogue also limited the ability of fibroblasts to subsequently promote colonocyte-
anchorage-independent growth. In contrast, fibroblasts pre-exposed to 4-HNE in
monoculture strongly increased the ability of Co(m) colonocytes to form colonies.
Domains
CancerOrigin | Publisher files allowed on an open archive |
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