Spheroid Cultures of Primary Urothelial Cancer Cells: Cancer Tissue-Originated Spheroid (CTOS) Method.

Increasingly, it has been recognized that studying cancer samples from individual patients is important for the development of effective therapeutic strategies and in endeavors to overcome therapy resistance. Primary cultures of cancer cells acutely dissected from individual patients can provide a platform that enables the study and characterization of individual tumors. To that end, we have developed a method for preparing cancer cells in the form of multi-cellular spheroids. The cells can be derived from patient tumors (primary cells), from patient-derived xenografts, or from genetically- or chemically induced animal tumors. This method of culturing spheroids composed of cells derived from cancer tissues can be applied to various types of cancer, including urothelial cancer. The method is based on the principle of retaining cell-cell contact throughout cancer cell preparation and culturing. The first step is a partial digestion of the tumor specimen into small fragments; these fragments spontaneously form spheroidal shapes within several hours. The spheroid is referred to as a cancer tissue-originated spheroid (CTOS). The advantage of the CTOS method is that it allows one to prepare pure cancer cells at high yield. CTOSs can be stably cultured in serum-free conditions. The CTOS method can be applied to drug sensitivity assays, drug screening, and analyses of intracellular signaling. Moreover, the CTOS method provides a platform for studying the nature of cancer cell clusters.