1982 Chapters (Layout Features)

Actin Organization as an in Vitro Assay for Tumorigenicity

Pollack, Robert; Nicholson, Nancy; Alcorta, David; Verderame, Michael; Smith, Katy; Steinberg, Bettie

The endpoints of in vivo and in vitro assays applied to cells after exposure to a potential oncogenic transforming agent are cellular tumorigenicity and transformation. Tumors are failures of in vivo growth control; transformations are failures of in vitro growth control. Many agents cause tumors in vivo, many agents transform normal cultured cells, and some agents do both. However, even when caused by a single agent, the in vivo and in vitro endpoint assays show only a partial overlap. That is, some but not all tumors will grow as transformed cells in culture, and some but not all in vitro transformants will be tumorigenic on injection into susceptible animals (Shin et ai., 1975). Recently, we have described a subset of in vitro phenotypic changes that correlate with in vivo tumorigenicity (Steinberg et ai., 1979; Barrett et ai., 1979; Pollack, 1981). In this chapter, we will describe recent studies on one of the in vitro changes linked to tumorigenicity, the disruption in organization of cytoskeletal actin.