Cultured Bloom's syndrome substrains: a relationship between growth in low serum and the expression of double minute chromosomes.
Four Bloom's syndrome fibroblast strains were examined for chromosome changes, immortalization, tumorigenicity, anchorage independent growth, and the ability to grow in low serum. Only one strain (GM 1492) exhibited some of these characteristics, which are generally associated with neoplastic cells. Strain GM 1492 also exhibited a low frequency of cells that contained double minute chromosomes. Substrains from GM 1492 were cloned, and showed that some of the above characteristics were expressed as a heritable trait. Karyotype instability (heteroploidy) was seen in all clones studied, with modal chromosome numbers ranging from near-diploid to near-tetraploid, as confirmed by DNA content distributions. Although no clones studied were tumorigenic in nude mice or immortalized, some showed an increased cellular proliferative capacity. Several clones were isolated after growth in 1% fetal bovine serum, and these all showed an increased expression of double minute chromosomes. Two of these 1% serum-isolated clones, (1492/clone 3-1% and clone 8-1%) were further studied by G-banding analysis, and found to show specific chromosomal anomalies. Clone 3 showed monosomy for chromosomes #4, #13, and #19, along with the absence of both copies of chromosome #7 but with both i(7p) and i(7q) chromosomes consistently seen. Clone 8 showed monosomy for chromosome #13. Preliminary experiments using DNA slot blots indicated that erb a and b, v-fes, v-mos, c-myc, n-myc, v-src, and v-sis showed no sequence amplification in GM 1492 cells or subclones.
D000818:Animals; D001816:Bloom Syndrome / Q000235:genetics* / Q000473:pathology; D002448:Cell Adhesion; D002455:Cell Division; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D003470:Culture Media; D005347:Fibroblasts / Q000473:pathology / Q000648:ultrastructure; D005434:Flow Cytometry; D006801:Humans; D007621:Karyotyping; D051379:Mice; D008819:Mice, Nude; D011003:Ploidies; D014410:Tumor Stem Cell Assay
D003470:Culture Media