Cell lines from grc congenic strains of rats having different susceptibilities to chemical carcinogens.
The growth and reproduction complex (grc-) strains of rats have a 70-kilobase deletion in the major histocompatibility complex (MHC)-linked grc-G/C region that is associated with embryonic death, developmental defects, and an increased susceptibility to chemical carcinogens. To study further the effects associated with the deletion, fibroblastic cell lines from grc-, grc+, and grc+/- rat embryos were developed: BIL-derived cell lines are congenic for the MHC and grc, whereas R16-derived cell lines are congenic for the grc alone. In early passages, all cell lines expressed the MHC class I antigen RT1.A, had a diploid chromosome number, and did not display anchorage-independent growth or in vivo tumorigenicity. The grc- cells [median population doubling time (PDT), 47 h] grew more slowly than the grc+ (PDT, 30.5 h) and grc+/- (PDT, 33 h) cells. All cells underwent crisis, but the crisis stage began earlier and lasted longer in the grc- cells. The established grc- cell lines (PDT, 32.5 h) grew faster than the grc+ (PDT, 48.5 h) and grc+/- (PDT, 54 h) cell lines. Two of the three BIL-derived grc- lines that survived crisis became anchorage independent in tissue culture and tumorigenic in histocompatible F1 rats (highly malignant fibrosarcomas) at passages 33 and 48, respectively; by contrast, none of the R16-derived grc- cell lines transformed. None of 8 grc+ or 8 grc+/- cell lines that survived crisis displayed anchorage-independent growth or tumorigenicity under the same conditions up to passage 50. All of the established cell lines, including the two tumorigenic ones, expressed MHC class I antigens. Southern and Northern blot analyses of BIL-derived cell lines before and after crisis showed that they all constitutively expressed H-ras and Rb and that no cell line showed rearrangement, amplification, or overexpression of c-myc, H-ras, Rb, and p53 either before or after crisis. These observations indicate that: (a) the homozygous grc- deletion is necessary but not sufficient for in vitro transformation; (b) another genetic factor(s) required for transformation is linked to, or possibly in, the MHC; and (c) passage through crisis, spontaneous transformation, or carcinogen treatment does not alter the cellular expression of MHC class I antigens or of several oncogenes and tumor suppressor genes.
Lu
D
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Department of Pathology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
Kunz
H W
HW
Melhem
M F
MF
Gill
T J
TJ
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D015197:Carcinogenicity Tests; D002448:Cell Adhesion; D002455:Cell Division / Q000235:genetics; D002461:Cell Line, Transformed; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects* / Q000473:pathology; D017353:Gene Deletion; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D008297:Male; D008769:Methylnitronitrosoguanidine; D012150:Polymorphism, Restriction Fragment Length; D051381:Rats
D015395:Histocompatibility Antigens Class I; D008769:Methylnitronitrosoguanidine; D015127:9,10-Dimethyl-1,2-benzanthracene