Reversion of tumorigenicity and decreased agarose clonability after EBV conversion of an IgH/myc translocation-carrying BL line.
The Epstein-Barr virus (EBV)-negative Burkitt lymphoma (BL) line BL-41, and 5 independently established EBV-converted sublines, derived by infection with a transforming (B95-8) or a nontransforming (P3HR1) strain of EBV, were compared for clonability in semi-solid agarose and for tumorigenicity in immuno-suppressed mice. One P3HR1 viral convertant and 3 out of 4 B95-8 virus-converted sublines had a high (greater than 40%) agarose clonability, like the BL 41 parent, and were slightly more tumorigenic than BL-41. In contrast, the fourth B95-8 converted subline, BL-41/95, was virtually non-tumorigenic and its agarose clonability was much lower (3-23%). It showed a more drastic shift towards an LCL-like phenotype than the other convertants as reflected by high HLA class-I and EBV-encoded latent membrane protein (LMP) expression. BL 41/95 still contains the 8;14 IgH/myc translocation, carried by the parental line, and maintains the same relatively high steady-state level of c-myc mRNA and protein as the highly tumorigenic convertants. We conclude that the tumorigenicity of BL41/95 has been suppressed by a gene that acts at a level beyond the expression of the activated oncogene, in the same way as the revertants isolated from ras and SV-40-transformed cultures (Klein, 1987b; Bassin and Noda, 1987).
Torsteinsdóttir
S
S
Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
Andersson
M L
ML
Avila-Cariño
J
J
Ehlin-Henriksson
B
B
Masucci
M G
MG
Klein
G
G
Klein
E
E
D000818:Animals; D002051:Burkitt Lymphoma / Q000235:genetics* / Q000473:pathology; D002472:Cell Transformation, Viral; D003001:Cloning, Molecular; D003470:Culture Media; D051379:Mice; D016274:Oncogene Protein p55(v-myc); D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D012191:Retroviridae Proteins / Q000235:genetics*; D012685:Sepharose; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured / Q000473:pathology
D003470:Culture Media; D016274:Oncogene Protein p55(v-myc); D012333:RNA, Messenger; D012334:RNA, Neoplasm; D012191:Retroviridae Proteins; D012685:Sepharose