Materials and methods for treatment of cancer and identification of anti-cancer compounds

Abstract

The subject invention pertains to the treatment of tumors and cancerous tissues and the prevention of tumorigenesis and malignant transformation through the modulation of JAK/STAT3 intracellular signaling. The subject invention concerns pharmaceutical compositions containing cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof. Another aspect of the invention concerns methods of inhibiting the growth of a tumor by administering a cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, to a patient, wherein the tumor is characterized by the constitutive activation of the JAK/STAT3 intracellular signaling pathway. The present invention further pertains to methods of moderating the JAK and/or STAT3 signaling pathways in vitro or in vivo using cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof. Another aspect of the present invention concerns a method for screening candidate compounds for JAK and/or STAT3 inhibition and anti-tumor activity.

We claim: 
     
         1 . A method for treating cancer comprising administering cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, to a patient in need of such treatment. 
     
     
         2 . The method according to  claim 1 , wherein the analog is a compound of structure I, or a pharmaceutically acceptable salt thereof: 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  can each be the same or different, and are each selected from the group consisting of H, O, hydroxyl, alkyl, alkenyl, alkynyl, halogen, alkoxy, aryl and heteroaryl. 
       
     
     
         3 . The method according to  claim 1 , wherein the analog is selected from the group consisting of cucurbitacin A, cucurbitacin B, cucurbitacin D, cucurbitacin E, cucurbitacin Q, and tetrahydro-cucurbitacin I. 
     
     
         4 . The method according to  claim 1 , wherein the cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, inhibits the JAK2 signaling pathway, the STAT3 signaling pathway, or both the JAK2 and STAT3 signaling pathways. 
     
     
         5 . The method according to  claim 1 , wherein the analog inhibits the STAT3 signaling pathway, but does not inhibit the JAK2 signaling pathway. 
     
     
         6 . The method according to  claim 1 , wherein the cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, inhibits both the JAK2 and STAT3 signaling pathways. 
     
     
         7 . The method according to  claim 1 , wherein the cancer is characterized by abnormal STAT3 pathway activity. 
     
     
         8 . The method according to  claim 1 , wherein the cancer is characterized by abnormal JAK2 pathway activity and abnormal STAT3 pathway activity. 
     
     
         9 . The method according to  claim 1 , wherein the compound inhibits growth of the tumor. 
     
     
         10 . The method according to  claim 1 , wherein the cancer is selected from the group consisting of lung cancer, pancreatic cancer, colon cancer, ovarian cancer, and breast cancer. 
     
     
         11 . The method according to  claim 1 , wherein cucurbitacin I, or a pharmaceutically acceptable salt thereof, is administered to the patient. 
     
     
         12 . The method according to  claim 1 , wherein the route of said administration is selected from the group consisting of intravenous, intramuscular, oral, and intra-nasal. 
     
     
         13 . A pharmaceutical composition comprising cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, and a pharmaceutically acceptable carrier or diluent. 
     
     
         14 . The pharmaceutical composition of  claim 13 , wherein said analog is a compound of structure I, or a pharmaceutically acceptable salt thereof: 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  can each be the same or different, and are each selected from the group consisting of H, O, hydroxyl, alkyl, alkenyl, alkynyl, halogen, alkoxy, aryl and heteroaryl. 
       
     
     
         15 . The pharmaceutical composition of  claim 13 , wherein said analog is selected from the group consisting of cucurbitacin A, cucurbitacin B, cucurbitacin, D, cucurbitacin E, cucurbitacin Q, and tetrahydro-cucurbitacin I. 
     
     
         16 . The pharmaceutical composition of  claim 13 , wherein the composition further comprises an immunomodulating agent. 
     
     
         17 . The pharmaceutical composition of  claim 13 , wherein the composition further comprises an agent selected from the group consisting of an antioxidant, free radical scavenging agent, peptide, growth factor, antibiotic, bacteriostatic agent, immunosuppressive, anticoagulant, buffering agent, anti-inflammatory agent, anti-pyretic, time-release binder, anesthetic, steroid, and corticosteroid. 
     
     
         18 . An article of manufacture useful in treating cancer, said article containing a pharmaceutical composition comprising cucurbitacin I, or a pharmaceutically acceptable salt or analog thereof, and a pharmaceutically acceptable carrier or diluent. 
     
     
         19 . A method of screening a substance for anti-tumor activity, said method comprising:
 a. applying cells to a substrate;   b. contacting the cells with one or more candidate substances;   c. permeabilizing the cells;   d. contacting a ligand specific for phosphotyrosine-STAT3 protein with the cells, wherein the ligand is directly or indirectly associated with a detectable label; and   e. detecting the label, thereby detecting the presence of phosphotyrosine-STAT3 protein within the cells.   
     
     
         20 . A kit for screening one or more substances for antitumor activity comprising a ligand specific for phosphotyrosine-STAT3 protein, wherein the ligand is directly or indirectly associated with a detectable label; and at least one of the following:
 a. cells for screening the candidate substances for phosphotyrosine-STAT3 inhibitory activity; and   b. a substrate for applying the cells.