Cytotoxic ribonuclease variants
This invention relates to cytotoxic variants of human ribonuclease 1 (RNase 1) identified through analysis of the interaction between RNase 1 and the human ribonuclease inhibitor (hRI) as defined by the three dimensional (3-D) atomic structure of the RNase1 hRI complex. Also disclosed is the 3-D structure of the hRI•RNase 1 complex and methods for designing the RNase 1 variants.
1. A method for inhibiting the proliferation of cancer cells, comprising delivering to the cells an effective amount of an engineered human Ribonuclease (RNase 1) polypeptide, said polypeptide comprising SEQ ID NO:2 except for one or more amino acid substitutions in the region of amino acid residues 85 to 94 and one or more amino acid substitutions selected from the group consisting of substitutions at position 4, 38, 39, 67, and 118 of SEQ ID NO:2.
2. The method of claim 1 , wherein said amino acid substitutions at positions 4, 38, 39, 67 and 118 are R4C, G38R, R39G, N67R, and V118C.
3. The method of claim 1 , wherein said amino acid substitution in the region of amino acid residues 85 to 94 is N88L.
4. The method of claim 1 , wherein said amino acid substitution in the region of amino acid residues 85 to 94 is G89R.
5. The method of claim 1 , wherein said amino acid substitution in the region of amino acid residues 85 to 94 is R91G.
6. A method for inhibiting the proliferation of cancer cells, comprising delivering to the cells an effective amount of an engineered human Ribonuclease (RNase 1) polypeptide, said polypeptide comprising SEQ ID NO:2 except for one or more amino acid substitutions in the region of amino acid residues 85 to 94 and one or more of the following amino acid substitutions: R4C, G38R, R39G, N67R, or V118C relative to SEQ ID NO:2.
7. A method for inhibiting the proliferation of cancer cells, comprising delivering to the cells an effective amount of an engineered human Ribonuclease (RNase 1) polypeptide, said polypeptide comprising SEQ ID NO:2 except for one or more amino acid substitutions in the region of amino acid residues 85 to 94 and one or more amino acid substitutions at position 4, 38, 39, 67 or 118 of SEQ ID NO:2.
8. The method of claim 7 , wherein said amino acid substitutions at position 4, 38, 39, 67 or 118 are R4C, G38R, R39G, N67R, and V118C.
9. The method of claim 7 , wherein said amino acid substitution in the region amino acid residues 85 to 94 is N88L.
10. The method of claim 7 , wherein said amino acid substitution in the region of amino acid residues 85 to 94 is G89R.
11. The method of claim 7 , wherein said amino acid substitution in the region of amino acid residues 85 to 94 is R91G.
12. The method of claim 1 , wherein the amino acid substitutions are R4C, G38R, R39G, N67R, N88L, G89R, R91G, and V118C.
13. The method of claim 6 , wherein the amino acid substitutions are R4C, G38R, R39G, N67R, N88L, G89R, R91G, and V118C.
14. The method of claim 7 , wherein the amino acid substitutions are R4C, G38R, R39G, N67R, N88L, G89R, R910, and V118C.
15. A method for inhibiting the proliferation of cancer cells, comprising delivering to the cells an effective amount of an engineered human Ribonuclease (RNase 1) polypeptide, said polypeptide comprising SEQ ID NO:2 except for the following amino acid substitutions: R4C, G38R, R39G, N67R, N88L, G89R, R91G, and V118C relative to SEQ ID NO:2.
16. The method of claim 1 , 6 or 7 , wherein the engineered RNase 1 retains ribonucleolytic activity relative to SEQ ID NO:2.
17. The method of claim 1 , 6 or 7 , wherein the engineered RNase 1 exhibits enhanced cytotoxic activity relative to SEQ ID NO: 2.
18. The method of claim 1 , 6 or 7 , wherein the engineered RNase 1 exhibits a lower binding affinity for hRI than SEQ ID NO:2.
19. The method of claim 1 , 6 or 7 , wherein the engineered RNase 1 retains ribonucleolytic activity, exhibits enhanced cytotoxic activity relative to SEQ ID NO: 2, and has a lower binding affinity for hRI than SEQ ID NO:2.
20. The method of claim 1 , 6 or 7 , wherein the one or more amino acid substitutions in SEQ ID NO:2 electrostatically repel and/or sterically hinder binding of human Ribonuclease Inhibitor (hRI) to the engineered RNase 1.