The tumor microenvironment determines tumor characteristics, and its recapitulation via in vitro tissue culture conditions is necessary for better understanding of molecular mechanisms of tumor behaviors and development of novel therapy. Rhabdomyosarcoma is a mesenchymal tumor that originates limb muscles. To assess the possible utility of the decellularized materials that contain native components of the microenvironment for the optimal humanized spheroid formation, we demonstrated co-culture of decellularized muscle extracts and rhabdomyosarcoma cells. The decellularized muscle extracts were prepared using a detergent, solubilized via pepsin digestion, and used for the spheroid culture of rhabdomyosarcoma cells in a low-attachment tissue culture plate. Here, we confirmed that these extracts contained proteins whose expression was unique to muscles. When rhabdomyosarcoma cells formed spheroids with decellularized muscle extracts, they exhibited heterogeneous morphology and a unique protein expression pattern. We conclude that in vitro cancer models established using decellularized tissue extracts from the originating organ have the potential to recapitulate features of in vivo tumor cells by providing the components of the tumor microenvironment. The precise molecular mechanisms for the interaction of cells and decellularized tissues are worth further investigation.
A complex of carboxylesterase and transferrin was obtained after cytosolic proteins in the mouse liver were separated by a combination of non-denaturing two-dimensional electrophoresis (2DE) and reversible staining. At the site where the complex was separated on the 2DE gel, the complex retained esterase activity because the relative intensity of the fluorescent esterase substrate was 1.6-fold higher than that within the 2DE gel in the absence of protein. Furthermore, the complex was extracted from the 2DE gel and bound to antibody-conjugated protein G plus A (protein A/G) agarose by non-denaturing electrophoresis after separation and detection. The esterase activity was retained after the complex was extracted and bound to antibody-conjugated protein A/G agarose. These results indicate that intact protein complexes were separated, detected, and extracted by non-denaturing electrophoresis.