S. Ando et al., Role of IRS-1 signaling in insulin-induced modulation of estrogen receptors in breast cancer cells, BIOC BIOP R, 253(2), 1998, pp. 315-319
Citations number
25
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Cross-talk between steroid hormones and polypeptide growth factors regulate
s the growth of hormone-responsive breast cancer cells. For example, in the
MCF-7 human breast cancer cell line, insulin upregulates estrogen receptor
(ER) content and binding capacity. Since the insulin receptor (IR) substra
te 1 (IRS-1) is one of the core signaling elements transmitting mitogenic a
nd metabolic effects of insulin, we investigated whether IRS-1 is also requ
ired for the insulin-induced function of the ER. The effects of insulin on
the ER were compared in MCF-7 cells and MCF-7-derived cell lines with decre
ased levels (by similar to 80%) of IRS-1 due to the expression of IRS-1 ant
isense RNA. The severe IRS-1 deficiency in MCF-7 cells was associated with
(1) reduced mitogenic response to 20 ng/ml insulin and 10% calf serum (CS),
but not to 1 nM estradiol (E2); (2) loss of insulin-E2 synergism; (3) up-r
egulation of ER protein expression and binding capacity; and (4) loss of in
sulin-induced regulation of ER tyrosine phosphorylation. In conclusion, the
data confirm the existence of the IR-ER cross-talk and suggest that IRS-l-
dependent signaling may contribute to the negative regulation of the ER exp
ression and function in MCF-7 cells. (C) 1998 Academic Press.