Prospective identification and characterization of breast cancer stem cells

Abstract

A small percentage of cells within an established solid tumor have the properties of stem cells. These solid tumor stem cells give rise both to more tumor stem cells and to the majority of cells in the tumor that have lost the capacity for extensive proliferation and the ability to give rise to new tumors. Thus, solid tumor heterogeneity reflects the presence of tumor cell progeny arising from a solid tumor stem cell. We have developed a xenograft model in which we have been able to establish tumors from primary tumors via injection of tumors in the mammary gland of severely immunodeficient mice. These xenograft assay have allowed us to do biological and molecular assays to characterize clonogenic solid tumor stem cells. We have also developed evidence that strongly implicates the Notch pathway, especially Notch 4, as playing a central pathway in carcinogenesis. This discovery is the basis for solid tumor stem cell compositions, methods for distinguishing functionally different populations of tumor cells, methods for using these tumor cell populations for studying the effects of therapeutic agents on tumor growth, and methods for identifying and testing novel anti-cancer therapies directed to solid tumor stem cells.

1 - 31 . (canceled) 
     
     
         32 - 49 . (canceled) 
     
     
         50 . A method for treating cancer the method comprising: administering to a patient having a solid tumor a therapeutically effective amount of a Notch4 antagonist. 
     
     
         51 . The method of  claim 50 , wherein the therapeutically effective amount is an amount sufficient to cause cell death of or inhibit the proliferation of the cells in the solid tumor. 
     
     
         52 . The method of  claim 50 , wherein the solid tumor comprises solid tumor stem cells. 
     
     
         53 . The method of  claim 52 , wherein the therapeutically effective amount is an amount sufficient to reduce the percentage of the solid tumor stem cells relative to solid tumor cells in the solid tumor. 
     
     
         54 . The method of  claim 50 , wherein the Notch4 antagonist is directed against an extracellular domain of a Notch4 polypeptide. 
     
     
         55 . The method of  claim 53 , the Notch4 antagonist is an antibody that specifically binds to Notch4. 
     
     
         56 . The method of  claim 50 , wherein the Notch4 antagonist is directed against a Notch4 ligand. 
     
     
         57 . The method of  claim 56 , wherein the Notch4 antagonist is an antibody against a Notch4 ligand. 
     
     
         58 . The method of  claim 52 , wherein the solid tumor stem cells are characterized by:
 (i) expressing CD44;   (ii) not expressing detectable levels of one or more LINEAGE markers selected from the group consisting of CD2, CD3, CD10, CD14, CD16, CD31, CD45, CD64, and CD140b; and   (iii) not expressing CD24 or expressing low levels of CD24.   
     
     
         59 . The method of  claim 52 , wherein the solid tumor stem cells express the cell surface marker CD44. 
     
     
         60 . The method of  claim 52 , wherein the solid tumor stem cells do not express CD24. 
     
     
         61 . The method of  claim 52 , wherein the solid tumor stem cells express lower levels of CD24 than the mean expression of CD24 by non-tumorigenic cancer cells of the solid tumor. 
     
     
         62 . The method of  claim 52 , wherein the solid tumor stem cells fail to express at least one LINEAGE maker selected from CD2, CD3, CD10, CD14, CD16, CD31, CD45, CD64, and CD140b. 
     
     
         63 . The method of  claim 58 , wherein the solid tumor stem cells are further characterized by the expression of B38.1. 
     
     
         64 . The method of  claim 58 , wherein the solid tumor stem cells are further characterized by expressing epithelial specific antigen (ESA). 
     
     
         65 . The method of  claim 52 , wherein the solid tumor stem cells express the cell surface marker B38.1. 
     
     
         66 . The method of  claim 52 , wherein the solid tumor stem cells express the cell surface marker epithelial specific antigen (ESA). 
     
     
         67 . The method of  claim 50 , wherein the solid tumor is an epithelial cancer. 
     
     
         68 . The method of  claim 67 , wherein the epithelial cancer is a breast cancer or an ovarian cancer. 
     
     
         69 . The method of  claim 50 , wherein the solid tumor is a sarcoma. 
     
     
         70 . The method of  claim 50 , wherein the method further comprises administering a therapeutically effective amount of a second Notch4 antagonist. 
     
     
         71 . The method of  claim 70 , wherein the second Notch4 antagonist modulates the activity of a Notch4 ligand. 
     
     
         72 . The method of  claim 70 , wherein the second Notch4 antagonist inhibits Notch4 signaling. 
     
     
         73 . The method of  claim 70 , wherein the second Notch4 antagonist is an antibody. 
     
     
         74 . The method of  claim 70 , wherein the second Notch4 antagonist is an antibody directed against a Notch4 ligand. 
     
     
         75 . The method of  claim 52 , wherein the method further comprises administering a therapeutically effective amount of an antibody that selectively targets solid tumor stem cells.