Maintenance of differentiation capacity of HT-29 cells after radiation exposure.
OBJECTIVE
Following ionizing radiation exposure, intestinal crypt regeneration is possible but it is still not known if regenerating crypts give rise to differentiated functional epithelial cells on villi. The aim of this study was to demonstrate that irradiated progeny of enterocytic precursor cells are capable of proliferation and subsequent differentiation using the HT-29?cell line.


METHODS
Cells were cultured, irradiated (5 Gy or 10 Gy) and incubated in the presence or absence of butyrate (5 mM). Cell numbers, cell cycle parameters, alkaline phosphatase (ALP) activity, occludin labelling and gene expression were determined at different times post-exposure.


RESULTS
Butyrate-induced inhibition of cell growth and arrest in G0 phase was comparable in both sham and irradiated cells in addition to similar development of ALP activity and expression. Cells also formed a monolayer with tight junctions post-irradiation. Butyrate-stimulated modulation of integrin expression during differentiation was unchanged after radiation exposure. Genes known to be implicated in differentiation mechanisms, i.e., growth and transcription factors (vascular Epidermal Growth Factor, v-EGF ; Activating Transcription Factor 4, ATF4), cell cycle genes (Cyclin-Dependent Kinase Inhibitor 1A, CDKN1A/p21(Cip1/waf1)), were studied. Most responded similarly to the differentiation stimulus whether irradiated or not.


CONCLUSIONS
These results demonstrate that irradiated HT-29 cells still respond to butyrate to form a differentiated, functional epithelium.
Haton
Céline
C
Institut de Radioprotection et de Sûreté Nucleaire/DRPH/SRBE, Cedex, France.
Lebrun
Fabienne
F
Benderitter
Marc
M
Griffiths
Nina M
NM
D000469:Alkaline Phosphatase / Q000378:metabolism; D002087:Butyrates / Q000494:pharmacology; D002454:Cell Differentiation / Q000528:radiation effects*; D020895:Enterocytes / Q000166:cytology / Q000528:radiation effects*; D016193:G1 Phase / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D016192:Resting Phase, Cell Cycle / Q000187:drug effects
D002087:Butyrates; D000469:Alkaline Phosphatase