Method of producing cancer stem cells

Abstract

The present invention relates to a method of producing cancer stem cells that comprises culturing a living cell population containing cancer cells in the presence of a gel substance to obtain a living cell population containing cancer stem cells, wherein the gel substance is a material that induces expression of osteopontin in at least a portion of cells contained in the living cell population. Moreover, the present invention relates to an agent for inducing conversion of cancer cells to cancer stem cells that comprises a gel substance that induces expression of osteopontin in at least a portion of the cells contained in a living cell population. The gel substance is a synthetic polymer gel composed of, for example, double network gel, PNaSS gel, PCDME gel, PA gel, PAMPS gel, PDMA gel or PAAc gel. The present invention provides means and a method that enable the preparation of cancer stem cells in a relatively short period of time and at a relatively low culturing cost without requiring expensive equipment.

1 - 11 . (canceled) 
     
     
         12 . An agent for inducing conversion of cancer cells from brain, lung or ovarian cancer tissue to cancer stem cells, containing a gel substance that is a synthetic polymer gel that induces expression of osteopontin in cells present in a living cell population obtained from cancer tissue, and converts at least a portion of cells contained in the living cell population into cancer stem cells; and said synthetic polymer gel is composed of poly(sodium p-styrene sulfonate) (PNaSS) gel, poly-N-(carboxymethyl-N,N-dimethyl-2-(methacryloyloxy) ethanaminium (PCDME) gel, polyampholyte (PA) gel, poly(2-acrylamido-2 methyl-1-propanesulfonic acid) (PAMPS) gel, poly (N,N′-dimethylacrylamide) (PDMA) gel, poly(acrylic acid) (PAAc) gel, or double network gel having an interpenetrating network structure of PAMPS gel and PDMA gel. 
     
     
         13 . (canceled) 
     
     
         14 . The agent for inducing conversion according to  claim 12 , wherein the gel substance is in the form of a sheet or particles. 
     
     
         15 - 17 . (canceled) 
     
     
         18 . The agent for inducing conversion according to  claim 12 , wherein the initial elastic modulus of the synthetic polymer is 0.0026 MPa or more and 0.435 MPa or less. 
     
     
         19 . The agent for inducing conversion according to  claim 12 , wherein the synthetic polymer induces a 2- to 13-fold higher level of osteopontin expression in the living cell population obtained from cancer tissue, compared with the polystyrene culture dish. 
     
     
         20 . A method of testing an effect of a test substance on cancer stem cells from brain, lung or ovarian cancer tissue, comprising:
 culturing a living cell population from said cancer tissue and/or said cancer stem cells in the presence of a test substance and the agent for inducing conversion defined in  claim 12 .   
     
     
         21 . The method according to  claim 20 , wherein the living cell population containing cancer stem cells contains cells exhibiting a spherical structure. 
     
     
         22 . The method according to  claim 20 , wherein cells in the living cell population containing cancer stem cells have a higher expression level of Oct3/4, Sox2 and/or Nanog than that prior to culturing in the presence of the gel substance. 
     
     
         23 . The method according to  claim 20 , wherein the culturing is carried out in vitro. 
     
     
         24 . The method according to  claim 20 , wherein the living cell population containing cancer stem cells is a living cell population obtained by culturing a living cell population containing cancer cells in the presence of the gel substance. 
     
     
         25 . The method according to  claim 20  further comprising transplanting the cancer stem cell into mice. 
     
     
         26 . The method according to  claim 20 , wherein the double network gel is in the form of a sheet or particles.