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With the use of the isoschizomeric restriction endonucleases HpaII and MspI, we found that mouse tumour ornithine decarboxylase (ODC; EC 4.1.1.17) genes are extensively methylated. ODC genes in L1210 mouse leukaemia cells were apparently more methylated than in Ehrlich ascites carcinoma, as revealed by the use of HpaII endonuclease, yet the digestion of genomic DNA isolated from these two murine tumour cell lines with MspI, which cleaves at a CCGG sequence, also with internally methylated cytosine, resulted in an apparently identical restriction pattern. It is possible that the amplification of ODC genes in Ehrlich ascites-carcinoma cells in response to 2-difluoromethylornithine (DFMO) was associated with hypomethylation, or that less-methylated genes were amplified. A human myeloma (Sultan) cell line only revealed three separate hybridization signals when cleaved with HpaII. One of these signals was amplified under the pressure of DFMO. When cleaved with MspI, these three HpaII fragments disappeared and were replaced by a double signal of 2.3-2.4 kilobase-pairs (kbp) in size. The amplified ODC sequences in the Sultan myeloma cell line apparently originated from chromosome 2, as indicated by a unique hybridization signal in a 5.8 kbp HindIII fragment specific for the human ODC locus on chromosome 2. A comparison of different human cells, the Sultan myeloma, a lymphocytic B-cell leukaemia (Ball), normal mononuclear leucocytes and leucocytes obtained from leukaemia patients, revealed interesting differences in the methylation of ODC genes. The use of two restriction endonucleases (HpaII and CfoI), the cleavage site for both of which contains a CG sequence and which only cleave when cytosine is unmethylated, indicated that ODC genes in the lymphocytic leukaemia cells were much less methylated than those in the normal leucocytes or in the Sultan cells.
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
January 1988,
Advances in experimental medicine and biology,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
October 1991,
The Biochemical journal,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
September 1988,
Nucleic acids research,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
January 1983,
Methods in enzymology,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
September 1989,
Oncogene,
L Alhonen-Hongisto, and
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R Sinervirta, and
R Laine, and
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K Alitalo, and
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J Jänne
January 1985,
Biochemical and biophysical research communications,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
January 1991,
The Journal of steroid biochemistry and molecular biology,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
January 1989,
Progress in clinical and biological research,
L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
September 2000,
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L Alhonen-Hongisto, and
P Leinonen, and
R Sinervirta, and
R Laine, and
R Winqvist, and
K Alitalo, and
O A Jänne, and
J Jänne
April 1988,
Proceedings of the National Academy of Sciences of the United States of America,
