Tumor-initiating cells and methods for using same

Abstract

Isolated and enriched tumor-initiating cell populations, methods for preparing the same, and uses thereof.

1 . An isolated tumor-initiating cell population derived from a tumor cell population comprising at least 90% tumor-initiating cells, wherein the tumor-initiating cells (i) express 5T4 at a level that is at least 2-fold higher than non-tumorigenic cells of the same origin, (ii) are tumorigenic, (iii) are capable of migration, (iv) are capable of self-renewal, and (v) generate tumors comprising non-tumorigenic cells, 
     
     
         2 . The isolated tumor-initiating cell population of  claim 1 , which comprises at least 95% tumor-initiating cells. 
     
     
         3 . The isolated tumor-initiating cell population of  claim 1 , wherein the tumor-initiating cells comprise less than about 50% of the tumor cell population from which it was derived, such as less than about 33%, less than about 25%, less than about 15%, or less than about 10% of the tumor cell population from which it was derived. 
     
     
         4 . An enriched tumor-initiating cell population derived from a tumor cell population comprising tumor-initiating cells and non-tumorigenic cells, wherein the tumor-initiating cells (i) express 5T4 at a level that is at least 2-fold higher than non-tumorigenic cells of the same origin, (ii) are tumorigenic, (iii) are capable of migration, (iv) are capable of self-renewal, (v) generate tumors comprising non-tumorigenic cells, and (vi) are enriched at least 2-fold compared to the tumor cell population. 
     
     
         5 . The enriched tumor-initiating cell population of  claim 4 , wherein the tumor-initiating cells are enriched at least 5-fold compared to the tumor cell population, such as at least 10-fold, at least 50-fold, or at least 100-fold compared to the tumor cell population. 
     
     
         6 . The isolated tumor-initiating cell population of  claim 1 , which expresses 5T4 at a level that is at least 5-fold higher than non-tumorigenic cells of the same origin, such as at least 10-fold higher than non-tumorigenic cells of the same origin. 
     
     
         7 . The isolated tumor-initiating cell population of  claim 1 , which further expresses CD24 at a level that is at least 5-fold lower than non-tumorigenic cells of the same origin, and/or which further expresses CD44. 
     
     
         8 . The isolated tumor-initiating cell population of  claim 1 , which is derived from a lung tumor. 
     
     
         9 . The isolated tumor-initiating cell population of  claim 1 , wherein a subpopulation of about 10 cells or less of the isolated tumor-initiating cell population has the capacity to form a palpable tumor. 
     
     
         10 . A method of isolating or enriching a tumor-initiating cell population comprising:
 (a) providing dissociated tumor cells, wherein a majority of the cells express 5T4 at a low level and a minority of the cells express 5T4 at a high level;   (b) contacting the dissociated tumor cells with an agent that specifically binds to 5T4, such as an anti-5T4 antibody; and   (c) selecting cells that specifically bind to the agent of (b) to an extent that shows a high level of 5T4 expression that is at least about 2-fold greater than the low level;   whereby a tumor-initiating cell population is isolated or enriched.   
     
     
         11 . The method of  claim 10 , wherein the isolated or enriched tumor-initiating cell population comprises at least 95% tumor-initiating cells. 
     
     
         12 . The method of  claim 10 , whereby the tumor-initiating cell population is enriched in tumor-initiating cells at least 2-fold when compared to the dissociated tumor cells, such as at least 5-fold or at least 10-fold compared to the dissociated tumor cells. 
     
     
         13 . The method of  claim 11 , wherein the dissociated tumor cells are lung cancer cells. 
     
     
         14 . The method of  claim 10 , wherein the selecting cells is performed by flow cytometry, fluorescence activated cell sorting, panning, affinity column separation, or magnetic selection. 
     
     
         15 . The method of  claim 10 , further comprising:
 (d) contacting the dissociated tumor cells with an agent that specifically binds to CD44, such as an anti-CD44 antibody; and   (e) selecting cells that specifically bind to the agent of (d) to an extent that shows expression of CD44.   
     
     
         16 . The method of  claim 10 , further comprising:
 (d) contacting the dissociated tumor cells with an agent that specifically binds to CD24, such as an anti-CD24 antibody; and   (e) selecting cells that specifically bind to the agent of (d) to an extent that shows a low level of CD24 expression that is at least about 5-fold lower than non-tumorigenic cells of the same origin.   
     
     
         17 . The method of  claim 10 , further comprising:
 (d) contacting the dissociated tumor cells with an agent that specifically binds to CD24, such as an anti-CD24 antibody; and   (e) depleting cells that specifically bind to the agent of (d) to an extent that shows a high level of CD24 expression that is at least about 5-fold greater than non-tumorigenic cells of the same origin.   
     
     
         18 . The method of  claim 10 , further comprising:
 (d) contacting the dissociated tumor cells with one or more agents that specifically binds to a differentiation marker expressed by the tumor cells; and   (e) depleting the tumor-initiating cell population of cells that specifically bind to the one or more agents of (d).   
     
     
         19 . An isolated or enriched tumor-initiating cell population isolated prepared according to the method of  claim 10 . 
     
     
         20 . A method of testing efficacy of a cancer drug or candidate cancer drug comprising:
 (a) providing an isolated tumor-initiating cell population of  claim 1 ;   (b) contacting the tumor-initiating cells with a cancer drug or a candidate cancer drug; and   (c) observing a change in tumorigenic potential of the tumor-initiating cells following contacting the tumor-initiating cells with the cancer drug or candidate cancer drug.