chemical agents , such as disulfonamide derivatives of fluorene , anthracene , xanthene , dibenzosuberone and acridine , and similar heterocyclic ring structures , including salts thereof , that act as anti - cancer and anti - tumor agents , especially where such agents modulate the activity of the wnt / β - catenin signaling pathway , and serve to reduce β - catenin levels present in cells , such as cancer cells , or where the agents modulate levels of gene expression in cellular systems , including cancer cells , are disclosed , along with methods for preparing such agents , as well as pharmaceutical compositions containing such agents as active ingredients and methods of using these as therapeutic agents .