Suppression of src-induced transformed phenotype by expression of tropomyosin-1

Suppression of high M-r tropomyosins (TMs) is a common feature of transform ed cells. Previous work from this laboratory has demonstrated that the isof orm 1 of TM, TM1, acts as an anti-oncogene in ras-transformed murine fibrob lasts. In this study, we have investigated whether TM1 is a ras-specific su ppressor, or a general suppressor protein of the cellular transformation. V -src transformed fibroblasts, which express decreased TM1, were transduced with a full-length cDNA to overexpress TM1. Both the control and the transd uced cells expressed v-src kinase at comparable levels. TM1 expressing (src -T1) cells grew at a lower rate in monolayer, exhibited well spread, flat m orphology than the control cells. Enhanced expression of TM1 resulted in im proved microfilamental architecture. More significantly, src-T1 cells compl etely failed to grow under anchorage independent conditions. These data dem onstrate that TM1 is as an anti-oncogene of functionally diverse oncogenes, and it is a class II tumor suppressor protein.