Journal of Dental Research, Vol 77, 1700-1707, Copyright © 1998 by International & American Associations for Dental Research Online Journals
Serum or growth factor deprivation induces the expression of alkaline phosphatase in human gingival fibroblasts
T. Abe, Y. Hara, Y. Abe, Y. Aida and K. Maeda
Department of Periodontology and Endodontology, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
We have previously reported that the increased expression of alkaline
phosphatase (ALP) activity is a phenotypic characteristic of gingival
fibroblasts present in chronic inflammatory periodontal lesions. We
hypothesized that ALP might be induced in gingival fibroblasts by
environmental factors. In the present study, we investigated the factors
influencing the induction of ALP expression in fibroblasts derived from
healthy human gingiva. The withdrawal of serum from confluent cultures of
fibroblasts increased the number of cells positive for ALP activity and
protein, without their proliferation. Suramin, a growth factor antagonist,
induced ALP expression in cells cultured with serum. Serum re-addition or
exposure to platelet-derived growth factor-AB and/or insulin-like growth
factor I suppressed ALP induction and caused cell growth. ALP-positive
cells could survive for up to 6 weeks after serum deprivation, a condition
inducing cell death via apoptosis. These results demonstrate that serum or
growth factor deprivation induces the expression of ALP in gingival
fibroblasts. ALP expression is negatively correlated with cell growth and
accompanied by a change into serum-growth-factor-independent survival.
