Peptide inhibition of cytokine-stimulated aromatase activity in breast tissue fibroblasts.
The cytokine interleukin-6 (IL-6) and its soluble receptor (IL-6sR) can act synergistically to stimulate aromatase activity in cultured stromal fibroblasts derived from breast tissues. In this study, a 16 amino acid peptide, AROHIB, has been used in an attempt to block the ability of IL-6 plus IL-6sR to stimulate aromatase activity in stromal fibroblasts. Pre-incubation of cells with AROHIB for a 3-h period before the addition of IL-6 and IL-6sR resulted in a marked (67%) reduction in the ability of these factors to stimulate aromatase activity. AROHIB was found to be rapidly degraded when exposed to MCF-7 breast cancer cells or fibroblasts. Analysis by FAB-MS was used to identify the site of peptide cleavage. Subsequently, a series of 10 amino acid peptides, DP1-DP4, were designed, synthesised and tested for their ability to resist proteolytic degradation and to inhibit IL-6 plus IL-6sR-stimulated aromatase activity. Peptide DP2, a modified version of the active fragment of AROHIB, had N-acetyl and C-amino terminal protection and an internal D-amino acid (instead of L form) at the site of proteolytic cleavage. Using cells cultured in the presence of 2% stripped foetal calf serum, peptide DP2 resulted in a 74% reduction in cytokine-stimulated aromatase activity. Under serum-free conditions, peptides DP1-DP3 showed modest inhibitory properties. Results from this study suggest that it may be possible to develop small peptides to inhibit cytokine-stimulated aromatase activity in a tissue-specific manner.
Parish
D
D
Endocrinology and Metabolic Medicine, Imperial College School of Medicine, St. Mary's Hospital, W2 1NY, London, UK.
Purohit
A
A
Singh
A
A
Rosankiewicz
J
J
Ghilchik
M W
MW
Reed
M J
MJ
D000595:Amino Acid Sequence; D001141:Aromatase / Q000378:metabolism; D047072:Aromatase Inhibitors; D001940:Breast / Q000187:drug effects* / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D019947:Receptors, Interleukin-6 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000093242:Interleukin-6 Inhibitors
D001141:Aromatase; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D010455:Peptides; D019947:Receptors, Interleukin-6; D000093242:Interleukin-6 Inhibitors