Compositions for enhancing transport of molecules into cells
Compositions and methods for enhancing delivery of molecules, e.g. biological agents, into cells are described. The composition is a conjugate of the biological agent, preferably a nucleic acid analog having a substantially uncharged backbone, covalently linked to a peptide transporter moiety as described. Conjugation of the peptide transporter to a substantially uncharged nucleic acid analog, such as a morpholino oligomer, is also shown to enhance binding of the oligomer to its target sequence and enhance antisense activity.
1. A peptide-oligomer analog conjugate comprising a carrier peptide covalently linked to a nucleic acid analog, the nucleic acid analog comprising a substantially uncharged backbone and a targeting base sequence, and the carrier peptide consisting of ten to fifteen subunits selected from X and Y subunits, including eight to thirteen X subunits, two to four Y subunits, at least one linker subunit linking the nucleic acid analogue to the peptide carboxy terminus, wherein:
(a) each X subunit is independently an amino acid subunit comprising a side chain of the structure R 1 N═C(NH 2 )R 2 , where R 1 is H or R; R 2 is R, NH 2 , NHR, or NR 2 , where each R is independently lower alkyl or lower alkenyl and optionally comprises oxygen or nitrogen,
or R 1 and R 2 may together form a ring; and wherein the side chain is linked to the amino acid via R 1 or R 2 ; and
(b) each Y subunit is independently a hydrophobic amino acid, and
wherein each linker subunit comprises the formula —C(O)—(CH 2 ) n —NH, wherein n is an integer from 2 to 7.
2. The peptide-nucleic acid analog conjugate of claim 1 , wherein each Y subunit comprises a substituted or unsubstituted alkyl, alkenyl, alkynyl, aryl or aralkyl side chain, wherein the alkyl, alkenyl or alkynyl side chain includes at most one heteroatom for every six carbon atoms.
3. The peptide-nucleic acid analog conjugate of claim 1 , wherein the linker comprises a β-alanine subunit, a 6-aminohexanoic acid subunit or combinations thereof.
4. The peptide-nucleic acid analog conjugate of claim 1 , wherein each Y subunit is selected from the group consisting of phenylalanine, tyrosine, tryptophan, leucine, isoleucine, and valine.
5. The peptide-nucleic acid analog conjugate of claim 1 , wherein each X subunit is arginine.
6. The peptide-nucleic acid analog conjugate of claim 1 , wherein the carrier peptide has the formula (ArgYArg) 4 .
7. The peptide-nucleic acid analog conjugate of claim 6 , wherein each Y subunit is selected from the group consisting of phenylalanine, tyrosine, tryptophan, leucine, isoleucine, and valine.
8. The peptide-nucleic acid analog conjugate of claim 6 , wherein each Y subunit is phenylalanine.
9. The peptide-nucleic acid analog conjugate of claim 8 , wherein the linker comprises a β-alanine subunit, a 6-aminohexanoic acid subunit or combinations thereof.
10. The peptide-nucleic acid analog conjugate of claim 6 , wherein each Y subunit is tyrosine.
11. The peptide-nucleic acid analog conjugate of claim 10 , wherein the linker comprises a β-alanine subunit, a 6-aminohexanoic acid subunit or combinations thereof.
12. The peptide-nucleic acid analog conjugate of claim 6 , wherein the nucleic acid analog comprises a morpholino nucleic acid analog, the morpholino nucleic acid analog comprising morpholino subunits linked by phosphorus-containing linkages, the phosphorus-containing linkages linking the morpholino nitrogen of one morpholino subunit to an exocyclic carbon at the morpholino 3-position of an adjacent morpholino subunit.
13. The peptide-nucleic acid analog conjugate of claim 12 , wherein the morpholino subunits are linked by phosphorous-containing linkages in accordance with Formula (I):
wherein:
Y 1 is O;
Z is O;
X is alkyl, alkoxy, thioalkoxy or alkyl amino; and
Pj is a purine or pyrimidine base-pairing moiety effective to bind to a base in a polynucleotide by base-specific hydrogen bonding.
14. The peptide-nucleic acid analog conjugate of claim 13 , wherein X in Formula (I) is dimethylamino.
15. The peptide-nucleic acid analog conjugate of claim 6 , wherein the carrier peptide is attached to the 5′ terminus or the 3′ terminus of the nucleic acid analog.
16. The peptide-nucleic acid analog conjugate of claim 15 , wherein the carrier peptide is attached to the 5′ terminus of the nucleic acid analog.
17. The peptide nucleic-acid analog conjugate of claim 16 , wherein the carrier peptide is attached to the 5′ terminus of the nucleic acid analog via a piperazinyl moiety having the following structure:
18. The peptide-nucleic acid analog conjugate of claim 6 , wherein the targeting base sequence of the nucleic acid analog is targeted to an antisense target in a polynucleotide, wherein the antisense target is a splice site in a pre-mRNA, a translation start site in an mRNA, or a cis-acting element in a viral genome.