Figure 6.

Examples of transformed cellular transdifferentiation potential from human bone tumors. Mesenchymal lineage and differentiation. A. Demonstration in osteosarcoma (OS 99‐1) and chondrosarcoma (CS 828) cells of a subpopulation of Stro‐1 positive cells. Activation of osteogenic and adipogenic programs of differentiation in bone sarcoma cultures grown in specific differentiation media. Osteogenic lineage is indicated by expression of alkaline phosphatase and adipogenic by accumulation of lipid vacuoles stained with Oil‐red‐O. B. Preservation of multiple osteo/chondral mesenchymal lineage markers (Runx2, Runx3, alkaline phosphatase, osteocalcin, and bone‐sialo protein in both sarcospheres and adherent cultures demonstrated by RT‐PCR. C. Western blot analysis of lysates from representative bone sarcoma cell cultures for the protein expression of Oct 3/4, STAT3, and activated (phosphorylated, p) STAT3. β‐Actin was used as a positive control for loading, membrane transfer, and immunoblotting (all cultures showed positive staining of protein bands of appropriate sizes, as indicated). The inset between (B) and (C) shows floating, attached sarcospheres, and following attachment their immunostaining for the pluripotency‐associated markers Oct3/4 and Nanog. [From 27; copyright Neoplasia 2005, with permission.]