Subchromosomal Mapping of a Putative Transformation Suppressor Gene on Human Chromosome 1

We previously reported that the introduction of a normal human chromosome 1 via microcell‐mediated chromosome transfer suppressed the transformed phenotypes, including anchorage‐independent growth, of Kirsten murine sarcoma virus‐transformed NIH3T3 (DT) cells. Soft‐agar clones derived from DT‐#1 cells (DT cells with an intact transferred human chromosome 1) exclusively failed to retain an intact form of this chromosome. Thus, a gene(s) with a suppressive activity on this chromosome had probably been lost. We therefore attempted to identify a commonly deleted region on human chromosome 1 in these soft‐agar clones. Although eight of the 9 soft‐agar clones examined still contained regions on this chromosome, to a greater or lesser degree, four loci on 1q21 and 1q23‐q24 were commonly lost in all of them. Furthermore, the soft‐agar clones had growth properties similar to those of DT cells. Thus, chromosome and DNA analyses suggested that human 1q21 and/or 1q23‐q24 carries a transformation suppressor gene(s) which controls the transformed phenotypes of DT cells.