Compositions and methods for treating and diagnosing cancer
The present invention relates to compositions and methods for characterizing, diagnosing and treating cancer. In particular, the present invention identifies LGR5 as a protein over-expressed in solid tumor stem cell. The present invention further identifies an interaction between RSPO1 and LGR5 as an alternative pathway for the activation of beta-catenin signaling. In certain embodiments, the present invention provides biomolecules that disrupt functional signaling via a LGR protein, including, in certain embodiments, molecules that inhibit the interaction between one or more RSPO proteins and one or more LGR proteins, such as LGR5. In certain embodiments, the present invention provides methods of treating cancer comprising disrupting functional LGR signaling and inhibiting growth of a solid tumor comprising solid tumor stem cells.
1. A monoclonal antibody that specifically binds the extracellular domain of a leucine-rich repeat-containing G protein coupled receptor (LGR) protein, wherein the antibody inhibits the interaction between an R-spondin (RSPO) protein and the LGR protein.
2. The antibody of claim 1 , wherein the antibody is capable of inhibiting the growth of tumor cells expressing the LGR protein.
3. The antibody of claim 1 , wherein the antibody is capable of inhibiting beta-catenin signaling in cells expressing the LGR protein.
4. The antibody of claim 1 , wherein the antibody is capable of inhibiting RSPO activation of LGR signaling in cells expressing the LGR protein.
5. The antibody of claim 1 , wherein the LGR protein is LGR5.
6. The antibody of claim 5 , wherein the LGR5 is human LGR5.
7. The antibody of claim 6 , wherein the antibody binds amino acids 22-564 of human LGR5 (SEQ ID NO:1).
8. The antibody of claim 6 , wherein the RSPO protein is human RSPO1.
9. The antibody of claim 6 , wherein the RSPO protein is human RSPO3.
10. The antibody of claim 6 , wherein the antibody is capable of inhibiting beta-catenin signaling in cells expressing the LGR protein.
11. The antibody of claim 6 , wherein the antibody is capable of inhibiting RSPO activation of LGR signaling in cells expressing the LGR protein.
12. The antibody of claim 6 , wherein the antibody is capable of inhibiting the growth of tumor cells that express LGR5.
13. The antibody of claim 12 , wherein the antibody is a chimeric antibody, humanized antibody, human antibody, or an antibody fragment.
14. The antibody of claim 13 , wherein the antibody is humanized.
15. The antibody of claim 14 , wherein the antibody is an intact monoclonal antibody.
16. A pharmaceutical composition comprising the antibody of claim 15 and a pharmaceutically acceptable carrier.
17. The antibody of claim 13 , wherein the antibody fragment is a Fab, Fab′, F(ab′)2, Fv, or single chain Fv (scFv) antibody fragment.
18. The antibody of claim 1 , wherein the LGR is human LGR4.
19. The antibody of claim 1 , wherein the LGR is human LGR6.
20. The antibody of claim 1 , wherein the RSPO is human RSPO1.
21. The antibody of claim 1 , wherein the RSPO is human RSPO2.
22. The antibody of claim 1 , wherein the RSPO is human RSPO3.
23. The antibody of claim 1 , wherein the RSPO is human RSPO4.
24. The antibody of claim 1 , wherein the antibody is a chimeric antibody, a humanized antibody, a human antibody, or an antibody fragment.
25. The antibody of claim 24 , wherein the antibody is an intact monoclonal antibody.
26. The antibody of claim 24 , wherein the antibody fragment is a Fab, Fab′, F(ab′)2, Fv, or single chain Fv (scFv) antibody fragment.
27. A pharmaceutical composition comprising the antibody of claim 1 and a pharmaceutically acceptable carrier.
28. A cell line producing a monoclonal antibody that binds the extracellular domain of human LGR5, wherein the antibody inhibits the interaction between an RSPO protein and the LGR5.
29. The cell line of claim 28 , wherein the antibody binds amino acids 22-564 of human LGR5 (SEQ ID NO:1).
30. A monoclonal antibody that competes in a competitive binding assay with the 88M1 antibody produced by the hybridoma cell line having ATCC deposit number PTA-9342.
31. A monoclonal antibody that specifically binds the extracellular domain of an LGR protein, wherein the antibody inhibits RSPO activation of LGR signaling.
32. The antibody of claim 31 , wherein the LGR5 is human LGR5.
33. The antibody of claim 32 , wherein the antibody binds amino acids 22-564 of human LGR5 (SEQ ID NO:1).
34. The antibody of claim 32 , wherein the RSPO protein is human RSPO1 or RSPO3.
35. The antibody of claim 32 , wherein the antibody is a chimeric antibody, humanized antibody, human antibody, or an antibody fragment.
36. The antibody of claim 35 , wherein the antibody is humanized.
37. The antibody of claim 36 , wherein the antibody is an intact monoclonal antibody.
38. A pharmaceutical composition comprising the antibody of claim 37 and a pharmaceutically acceptable carrier.
39. The antibody of claim 35 , wherein the antibody fragment is a Fab, Fab′, F(ab′)2, Fv, or single chain Fv (scFv) antibody fragment.
40. A monoclonal antibody that specifically binds the extracellular domain of an LGR protein, wherein the antibody inhibits beta-catenin signaling.
41. The antibody of claim 40 , wherein the LGR5 is human LGR5.
42. The antibody of claim 41 , wherein the antibody binds amino acids 22-564 of human LGR5 (SEQ ID NO:1).
43. The antibody of claim 41 , wherein the RSPO protein is human RSPO1 or RSPO3.
44. The antibody of claim 41 , wherein the antibody is a chimeric antibody, humanized antibody, human antibody, or an antibody fragment.
45. The antibody of claim 44 , wherein the antibody is humanized.
46. The antibody of claim 45 , wherein the antibody is an intact monoclonal antibody.
47. A pharmaceutical composition comprising the antibody of claim 46 and a pharmaceutically acceptable carrier.
48. The antibody of claim 44 , wherein the antibody fragment is a Fab, Fab′, F(ab′)2, Fv, or single chain Fv (scFv) antibody fragment.