Alpha-fetoprotein “ring and tail” peptides
The invention relates to compounds that are analogs of a cyclic peptide, cyclo[EKTOVNOGN] (SEQ ID NO: 13), AFPep, that has anti-estrotrophic activity. The analogs of the invention include peptides and peptidomimetics that inhibit estrogen receptor-dependent cell proliferation. The compounds of the invention are useful for treating cell proliferative disorders or physiological conditions characterized by undesirable or unwanted estrogen induced cell proliferation, including breast cancer.
1. A cyclic peptide comprising a ring portion and a hydrophobic tail portion, said ring portion comprising from 5-9 amino acids, wherein said ring portion of said peptide comprises an amino acid sequence selected from the group consisting of:
AA 1 -AA 2 -AA 3 -AA 4 a)
wherein AA 1 is threonine, serine, valine or alanine;
AA 2 is hydroxyproline or serine;
AA 3 is valine, isoleucine, leucine or threonine; and
AA 4 is asparagine or glycine;
AA′ 1 -AA′ 2 -AA′ 3 -N-AA′ 4 b)
wherein AA′ 1 is threonine, serine, valine or alanine;
AA′ 2 is hydroxyproline or serine;
AA′ 3 is valine, isoleucine, leucine or threonine; and
AA′ 4 is hydroxyproline or asparagine; or
AA″ 1 -AA″ 2 -N-AA″ 3 c)
wherein AA″ 1 is hydroxyproline or serine;
AA″ 2 is valine, isoleucine, leucine or threonine; and
AA″ 3 hydroxyproline or asparagine; and
said hydrophobic tail portion comprises from 1 to 4 amino acids.
2. The cyclic peptide of claim 1 , wherein said tail portion comprises 1-4 amino acids that have hydrophobic side chains.
3. The cyclic peptide of claim 1 , wherein said peptide has anti-estrotrophic activity.
4. A cyclic peptide comprising a ring portion and a hydrophobic tail portion, said ring portion comprising from 5-9 amino acids, wherein said ring portion of said peptide comprises an amino acid sequence selected from TPVN (SEQ ID NO: 2), TOVN (SEQ ID NO: 3), TPVNP (SEQ ID NO: 4), TOVNP (SEQ ID NO: 5), TPVNO (SEQ ID NO: 6), TOVNO (SEQ ID NO: 7), PVNPG (SEQ ID NO: 8), OVNOG (SEQ ID NO: 9), KTOVN (SEQ ID NO: 10), KTOVNO (SEQ ID NO: 11), KTOVNOG (SEQ ID NO: 14), KTPVNPG (SEQ ID NO: 15) and EKTOVNOGN (SEQ ID NO: 13).
5. The cyclic peptide of claim 1 , wherein the ring portion of said peptide comprises the amino acid sequence EKTOVNOGN (SEQ ID NO. 13).
6. The cyclic peptide of claim 1 , wherein said tail portion comprises phenylalanine.
7. The cyclic peptide of claim 6 , comprising the amino acid sequence [EKTOVNOGN] (SEQ ID NO: 13) F.
8. The cyclic peptide of claim 1 , wherein said tail portion comprises isoleucine.
9. The cyclic peptide of claim 8 comprising the amino acid sequence [EKTOVNOGN]I (SEQ ID NO: 13).
10. The cyclic peptide of claim 1 , wherein said tail portion comprises phenylalanine and isoleucine.
11. The cyclic peptide of claim 10 comprising the amino acid sequence [EKTOVNOGN] (SEQ ID NO: 13) FI.
12. A method of reducing estrogen-stimulated growth of cells, the method comprising exposing said cells to the peptide of claim 1 .
13. The method of claim 12 , comprising exposing the cells to tamoxifen before, during, or after exposing the cells to the peptide.
14. A method for the treatment of breast cancer in a patient comprising administering to the patient a therapeutically effective amount of the peptide of claim 1 .
15. A pharmaceutical composition comprising a peptide of claim 1 and a pharmaceutically acceptable carrier.