Studies with cell hybrids of normal diploid cells fused with tumorigenic D98AH2 (D98) cells had implicated human chromosome 11 of a normal cell as carrying tumorigenicity suppressing information. The cervical carcinoma-derived D98 (HeLa) cells contain two copies of chromosome 11. In this study, analysis of restriction fragment length polymorphism of DNA from D98 cells digested with one of nine restriction endonucleases and hybridized with five DNA probes for highly polymorphic regions on the short arm of chromosome 11 detected no heterozygosity at the insulin (INS), Harvey murine sarcoma virus 1 (HRAS1), and the β-globin cluster (HBBC) regions. The low probability of an individual being homozygous at all these loci suggests that the Nos. 11 of the D98 cells are both copies of only one of the original homologs, or at least of the short arm segment examined. This indicates that the D98 cells could express altered or lost genes associated with tumorigenicity, even if such changes were recessive. In tumorigenically suppressed hybrids the Nos. 11 of the normal cell could then be complementing this genetic defect of the D98 cells
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