We examined a human gastric carcinoma cell line TMK-1 cytogenetically by G-banding technique. TMK-1 cells were characterized not only by numerical aberrations but also by structural rearrangements affecting various chromosomes. The modal chromosome number was found to be in the hypotriploid range with most ranging between 64 and 66. Flow cytometry revealed near triploid DNA histogram which was correlated well with chromosome counts. Gain of chromosome 7, 9, 11, and X was found in all of the 25 cells examined and trisomy of chromosome 3, 5, 10, 19, 21 and 22 was also frequently detected. Loss of Y chromosome was shown in all of the cells and monosomy of chromosome 6 and 13 was frequently detected. The most conspicuous rearrangements involved chromosome 6, 12, and 16 which showed complex nonreciprocal translocation. Twenty-two cells (88%) had isochromosome of 12q. A brief review is made of reported karyotype of human gastric cancers.

This study was supported in part by Grant-in-Aid for Cancer Research from the Ministry of Health and Welfare, Tokyo and Tsuchiya Medical Foundation, Hiroshima, Japan.