Saposin C-DOPS: a novel anti-tumor agent

1. A composition comprising

a phospholipid, wherein the phospholipid is dioleoylphosphatidylserine (DOPS),

an isolated saposin C-related polypeptide, wherein the polypeptide is selected from the group consisting of: (a) a polypeptide having the amino acid sequence at least 95 percent identical to the entire length of SEQ ID NO: 2; and (b) a polypeptide having the amino acid sequence identical to SEQ ID NO: 2; and

a pharmaceutically acceptable carrier;

wherein the polypeptide retains plasma membrane affinity;

wherein the phospholipid forms a nanovesicle incorporating the polypeptide;

and wherein the nanovesicle incorporating the polypeptide exhibits anti-tumor activity.

2. The composition of claim 1 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:50.

3. The composition of claim 1 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:10.

4. The composition of claim 1 wherein the composition is capable of inducing apoptosis in hyper-proliferating cells, wherein the hyper-proliferating cells are cancer cells.

5. The composition of claim 1 , wherein the polypeptide comprises at least 25 contiguous amino acids of SEQ ID NO: 2.

6. The composition of claim 1 , wherein the mass ratio of the polypeptide to the phospholipid is in the range from about 15:1 to about 3:10.

7. A method for modulating the distribution of an inner leaflet component in a plasma membrane of a hyper-proliferating cell of a subject comprising administering to the subject a therapeutically effective amount of the composition of claim 1 ;

wherein the inner leaflet component is phosphatidylserine; and

wherein the hyper-proliferating cell is a cancer cell.

8. The method of claim 7 , wherein the phosphatidylserine is dioleoylphosphatidylserine.

9. The method of claim 7 , wherein the distribution of the inner leaflet component in the outer leaflet of the plasma membrane is altered.

10. The method of claim 7 , wherein the concentration of the inner leaflet component in the outer leaflet is increased.

11. The method of claim 7 , wherein the method promotes cell death of the hyper-proliferating cell.

12. A method of modulating tumor volume in a subject, the method comprising administering a therapeutically effective amount of the composition of claim 1 .

13. The method of claim 12 , wherein the composition promotes cell death in hyper-proliferating cells, wherein the hyper-proliferating cells are cancer cells.

14. The method of claim 13 , wherein the cancer cells are selected from the group consisting of sarcoma, neuroblastoma, breast carcinoma, and squamous cell carcinoma cells.

15. The method of claim 12 , wherein the subject is a mammal.

16. The method of claim 15 , wherein the mammal is a human.

17. The method of claim 12 , wherein the tumor volume decreases.

18. The method of claim 12 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:50.

19. The method of claim 18 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:10.

20. A method of treating a cancer in a subject, the method comprising administering a therapeutically effective amount of the composition of claim 1 .

21. The method of claim 20 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:50.

22. The method of claim 21 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:10.

23. The method of claim 20 , wherein the composition promotes cell death in hyper-proliferating cells, wherein the hyper-proliferating cells are cancer cells.

24. The method of claim 23 , wherein the cell death occurs through apoptosis.

25. The method of claim 23 , wherein the cancer cells are selected from the group consisting of sarcoma, neuroblastoma, breast carcinoma, and squamous cell carcinoma cells.

26. The method of claim 20 , wherein the subject is a mammal.

27. The method of claim 26 , wherein the mammal is a human.

28. The method of claim 20 , wherein the composition is administered enterally, parenterally, subcutaneously, intravenously, intraperitoneally, or topically.

29. The method of claim 20 , wherein multiple doses of the composition are administered to the subject.

30. The method of claim 20 , wherein a single dose of the composition is administered to the subject.

31. An anti-tumor agent comprising a nanovesicle prepared by

(a) preparing a composition that comprises (i) a dried inner leaflet component, wherein the inner leaflet component is a phosphoplipid, wherein the phospholipid is dioleoylphosphatidylserine (DOPS) and (ii) a dried and isolated prosaposin-related polypeptide;

wherein the polypeptide has an amino acid sequence selected from the group consisting of the amino acid sequence set forth in SEQ ID NO: 1, the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO: 1, the amino acid sequence set forth in SEQ ID NO: 2, and the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO:2 and wherein the polypeptide retains plasma-membrane affinity;

wherein the molar ratio of the polypeptide to the dioleoylphosphatidylserine in the composition is in the range from 1:1 to 1:25;

in a pharmaceutically acceptable carrier;

(b) treating the composition to form a nanovesicle;

wherein the nanovesicle formed has a diameter in the range 10 to 800 nm;

and wherein the composition is capable of inducing apoptosis in hyper-proliferating cells, wherein the hyper-proliferating cells are cancer cells.

32. The anti-tumor agent of claim 31 , wherein the mass ratio of the polypeptide to the dioleoylphosphatidylserine is approximately 5:1.

33. The anti-tumor agent of claim 31 , wherein the mass ratio of the polypeptide to the dioleoylphosphatidylserine is approximately 15:7.

34. The anti-tumor agent of claim 31 , wherein the mass ratio of the polypeptide to the dioleoylphosphatidylserine is in the range from about 15:1 to about 3:10.

35. The anti-tumor agent of claim 31 , comprising approximately 10 μM polypeptide and approximately 30 μM dioleoylphosphatidylserine.

36. The anti-tumor agent of claim 31 , comprising approximately 10 μM polypeptide and approximately 70 μM dioleoylphosphatidylserine.

37. A composition consisting essentially of an anionic phospholipid nanovesicle consisting of dioleoylphosphatidylserine (DOPS) embedded with a biologically active saposin C-related polypeptide, wherein the polypeptide comprises the amino acid sequence that has at least 95% sequence identity to the amino acid sequence of the entire length of SEQ ID NO:2; and a pharmaceutically acceptable carrier; wherein the phospholipid nanovesicle exhibits anti-tumor activity.

38. The composition of claim 37 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:50.

39. The composition of claim 37 , wherein the molar ratio of the polypeptide to the phospholipid is in the range from about 1:1 to about 1:10.

40. The composition of claim 37 wherein the composition is capable of inducing apoptosis in hyper-proliferating cells upon contact, wherein the hyper-proliferating cells are cancer cells.

41. A process for the manufacture of a pharmaceutical agent comprising the steps of:

(a) preparing a composition that comprises (i) an inner leaflet component, wherein the inner leaflet component is a phospholipid, wherein the phospholipid is dioleoylphosphatidylserine (DOPS) and (ii) a prosaposin-related polypeptide, wherein the polypeptide is selected from the group consisting of: (a) a polypeptide having the amino acid sequence at least 95 percent identical to the entire length of SEQ ID NO: 2; and (b) a polypeptide having the amino acid sequence identical to SEQ ID NO: 2and wherein the polypeptide retains plasma-membrane affinity;

in a pharmaceutically acceptable carrier;

(b) treating the composition to form a nanovesicle;

wherein the nanovesicle formed exhibits anti-tumor activity.

42. A pharmaceutical agent comprising nanovesicles prepared by

(a) preparing a composition that comprises (i) an inner leaflet component, wherein the inner leaflet component is dioleoylphosphatidylserine (DOPS) and (ii) a prosaposin-related polypeptide;

wherein the polypeptide has an amino acid sequence selected from the group consisting of the amino acid sequence set forth in SEQ ID NO: 1, the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO: 1, the amino acid sequence set forth in SEQ ID NO: 2, and the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO:2 and wherein the polypeptide retains plasma-membrane affinity;

in a pharmaceutically acceptable carrier;

(b) treating the composition to form a nanovesicle;

wherein the nanovesicle formed exhibits anti-tumor activity.

43. The pharmaceutical agent of claim 42 , wherein the molar ratio of the polypeptide to the dioleoylphosphatidylserine (DOPS) is in the range from about 1:1 to about 1:50.

44. The pharmaceutical agent of claim 42 , wherein the nanovesicle has a diameter in the range 0.01 to 1 μm.

45. A process for the manufacture of a pharmaceutical agent comprising the steps of:

(a) preparing a composition that comprises (i) a dried inner leaflet component, wherein the inner leaflet component is dioleoylphosphatidylserine and (ii) a dried and isolated prosaposin-related polypeptide, wherein the polypeptide is selected from the group consisting of: (a) a polypeptide having the amino acid sequence at least 95 percent identical to the entire length of SEQ ID NO: 2; and (b) a polypeptide having the amino acid sequence identical to SEQ ID NO: 2and wherein the polypeptide retains plasma-membrane affinity;

wherein the molar ratio of the polypeptide to the inner leaflet component in the composition is in the range from 1:1 to 1:25;

in a pharmaceutically acceptable carrier;

(b) treating the composition to form a nanovesicle;

wherein the nanovesicle formed has a diameter in the range 10 to 800 nm and exhibits anti-tumor activity.

46. A pharmaceutical agent comprising nanovesicles prepared by

(a) preparing a composition that comprises (i) a dried inner leaflet component, wherein the inner leaflet component is dioleoylphosphatidylserine (DOPS) and (ii) a dried and isolated prosaposin-related polypeptide;

wherein the polypeptide has an amino acid sequence selected from the group consisting of the amino acid sequence set forth in SEQ ID NO: 1, the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO: 1, the amino acid sequence set forth in SEQ ID NO: 2, and the amino acid sequence that is at least 95 percent identical to the entire length of SEQ ID NO:2 and wherein the polypeptide retains plasma-membrane affinity;

wherein the molar ratio of the polypeptide to the inner leaflet component in the composition is in the range from 1:1 to 1:25;

in a pharmaceutically acceptable carrier;

(b) treating the composition to form a nanovesicle;

wherein the nanovesicle formed has a diameter in the range 10 to 800 nm and exhibits anti-tumor activity.