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.