Genetic analysis of Raf1, Mdm2, c-Myc, Cdc25a and Cdc25b proto-oncogenes in 2',3'-dideoxycytidine- and 1,3-butadiene-induced lymphomas in B6C3F1 mice.
We have previously identified activation of ras proto-oncogenes and inactivation of tumor suppressor genes including p53, p16(INK4a) and p15(INK4b) in 2',3'-dideoxycytidine (ddC)- and/or 1,3-butadiene (BD)-induced lymphomas derived from B6C3F1 (C57BL/6xC3H/He) mice, indicating that alterations of ras signaling pathway, p53 and pRb growth control pathways are important in the development of these chemically induced lymphomas. However, there is still a subset of tumors that displayed no changes in these genes. Thus, we investigated whether the Raf1, Mdm2, c-Myc, Cdc25a and Cdc25b proto-oncogenes, which are implicated in the ras or p53 or pRb pathways, are alternative oncogenic target genes. Analyses of gross genomic alterations by Southern blots failed to reveal rearrangement or amplification in any of the tumors examined. Frequent point mutations on the substrate binding domain of the Raf1 gene has been reported in 1-ethyl-1-nitrosourea (ENU)-induced murine lymphomas and lung tumors, along with a conspicuous lack of ras mutations [U. Naumann, I. Eisenmann-Tappe, U.R. Rapp, The role of raf kinases in development and growth of tumors, Recent Results Cancer Res., 143 (1997) 237-244]. To investigate whether Raf1 mutation is involved in our set of tumor especially those without ras mutations, the PCR-based single-strand conformation analyses (SSCA) and direct DNA sequencing were employed. No mutations but four genetic polymorphisms between C57BL/6 and C3H/He were found, with two of them reported as point mutations previously (op. cit.). The polymorphisms were utilized for allelic loss study of Raf1 locus. Losses of heterozygosity were found in six of 31 BD-induced lymphomas. These results indicate that genetic alterations of c-Myc, Cdc25, Raf1 and Mdm2 proto-oncogenes may not be involved in the development of ddC- and BD-induced lymphomas and the inactivation of tumor suppressor gene(s) located close to Raf1 gene might be important in the development of a subset of BD-induced lymphomas.
Zhuang
S
S
Division of Cell Biology, Department of Biomedicine and Surgery, Faculty of Health Sciences, Linköping University, Sweden. shizh@mcb.liu.se
Söderkvist
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002070:Butadienes / Q000633:toxicity*; D018797:Cell Cycle Proteins / Q000235:genetics; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D008223:Lymphoma / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D018807:Polymorphism, Single-Stranded Conformational; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics; D011519:Proto-Oncogenes / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D016047:Zalcitabine / Q000633:toxicity*; D020687:cdc25 Phosphatases / Q000235:genetics
D002070:Butadienes; D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D016047:Zalcitabine; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2; D019908:Proto-Oncogene Proteins c-raf; C517005:Cdc25a protein, mouse; D020687:cdc25 Phosphatases; C031763:1,3-butadiene