Let-7 microrna and mimetics thereof as therapeutics for cancer

Abstract

The present invention relates to methods to treat or prevent cancers in a subject, in particular the present invention relates to a method of treating and/or preventing cancer comprising targeting cancer stem cells by administering miRNAs which have reduced expression or are lacking in the cancer stem cells. In some embodiments, the miRNAs that are reduced or lacking in cancer stem cells are let-7 miRNAs. In alternative embodiments, the present invention relates to a method of treating and/or preventing cancer comprising targeting cancer stem cells by administering miRNAs which have increased expression levels in the cancer stem cells. Another aspect of the present invention relates to methods to enrich for a cancer stem cell population. Another aspect of the present invention relates to methods to identify miRNAs which contribute to the self-renewal capacity of cancer stem cells.

1 .- 112 . (canceled) 
     
     
         113 . A pharmaceutical composition comprising a let-7 miRNA, a binding moiety and a targeting moiety, wherein the binding moiety connects the let-7 miRNA to the targeting moiety and wherein the targeting moiety binds to the endothelial-specific marker (ESA)/Epithelial cell adhesion molecule (EpCAM) on the surface of a cancer cell or cancer stem cell, and wherein the let-7 miRNA binds to and inhibits a RNA transcript comprising a let-7 target sequence. 
     
     
         114 . The pharmaceutical composition of  claim 113 , wherein the let-7 target sequence comprises SEQ ID NO: 9 or SEQ ID NO: 10 or SEQ ID NO:11. 
     
     
         115 . The pharmaceutical composition of  claim 113 , wherein the let-7 miRNA is selected from the group consisting of let-7a, let-7a1, let-7b, let-7c, let-7d, let-7e and let-7f. 
     
     
         116 . The pharmaceutical composition of  claim 113 , wherein the miRNA is a pri-miRNA, pre-miRNA, mature miRNA effective in gene silencing. 
     
     
         117 . The pharmaceutical composition of  claim 113 , wherein the let-7 miRNA comprises SEQ ID NO:1-8. 
     
     
         118 . The pharmaceutical composition of  claim 113 , wherein the cancer is selected from at least one of the group consisting of a pre-cancer, malignant cancer, therapy resistant cancer, breast cancer 
     
     
         119 . The pharmaceutical composition of  claim 113 , wherein the targeting moiety is selected from the group consisting of: an antibody, a single chain antibody, a Fab portion of an antibody and a (Fab′)2 segment. 
     
     
         120 . The pharmaceutical composition of  claim 113 , wherein the binding moiety is a protein or a nucleic acid binding domain of a protein, and the binding moiety is fused to the carboxyl terminus of the targeting moiety. 
     
     
         121 . The pharmaceutical composition of  claim 113 , wherein the binding moiety is the protein protamine or nucleic acid binding fragment of protamine. 
     
     
         122 . A method of treating or preventing cancer in a subject wherein the cancer comprises a cancer stem cell expressing the endothelial-specific marker (ESA)/Epithelial cell adhesion molecule (EpCAM), the method comprising administering to the subject a pharmaceutical composition comprising an effective amount of:
 at least one let-7 miRNA agent;   a binding moiety, wherein the binding moiety associates with the let-7 miRNA agent and the targeting agent; and   a targeting moiety, wherein the targeting moiety binds to the endothelial-specific marker (ESA)/Epithelial cell adhesion molecule (EpCAM),   wherein the let-7 miRNA binds to and inhibits a RNA transcript comprising a let-7 target sequence which is expressed in the cancer stem cell, wherein inhibition of an RNA transcript comprising a let-7 target sequence inhibits proliferation of the cancer stem cell, thereby reducing or preventing the cancer in the subject.   
     
     
         123 . The method of  claim 122 , wherein the let-7 target sequence comprises SEQ ID NO: 9 or SEQ ID NO: 10 or SEQ ID NO:11. 
     
     
         124 . The method of  claim 122 , wherein the let-7 miRNA is selected from the group consisting of let-7a, let-7a1, let-7b, let-7c, let-7d, let-7e and let-7f. 
     
     
         125 . The method of  claim 122 , wherein the miRNA is a pri-miRNA, pre-miRNA, mature miRNA effective in gene silencing. 
     
     
         126 . The method of  claim 122 , wherein the let-7 miRNA comprises SEQ ID NO:1-8. 
     
     
         127 . The method of claim  21 , wherein the cancer is selected from at least one of the group consisting of a pre-cancer, malignant cancer, therapy resistant cancer, breast cancer. 
     
     
         128 . The method of  claim 122 , wherein the targeting moiety is selected from the group consisting of: an antibody, a single chain antibody, a Fab portion of an antibody and a (Fab′)2 segment. 
     
     
         129 . The method of  claim 122 , wherein the binding moiety is a protein or a nucleic acid binding domain of a protein, and the binding moiety is fused to the carboxyl terminus of the targeting moiety. 
     
     
         130 . The method of  claim 122 , wherein the binding moiety is the protein protamine or nucleic acid binding fragment of protamine. 
     
     
         131 . The method of  claim 122 , further comprising administering to the subject one or more additional cancer therapies selected from the group consisting of surgery, chemotherapy, radiotherapy, thermotherapy, immunotherapy, hormone therapy and laser therapy. 
     
     
         132 . The method of  claim 122 , wherein the subject is a mammal or a human.