Abstract
We recently selected a variant mouse L1210 leukaemia-cell line overproducing ornithine decarboxylase (ODC) (EC 4.1.1.17) as a result of chronic exposure to 2-difluoromethylornithine (DFMO) in the presence of micromolar concentrations of cadaverine. These cells, now grown for more than 2 years in the presence of DFMO and cadaverine, continued to accumulate ODC-specific mRNA in an amount 30-50 times higher than that in the parental cells, yet showing practically no changes in the gene dosage for the enzyme. However, analysis of the genomic DNA with the isoschizomeric restriction enzymes HpaII and MspI revealed that the ODC sequences in the overproducer cells were hypomethylated in comparison with the parental cells. The natural polyamines (putrescine, spermidine and spermine) were almost totally replaced by cadaverine and aminopropylcadaverine. Omission of cadaverine from the culture medium, but leaving 10 mM-DFMO, resulted in an about 10-fold ODC gene amplification within a few weeks. The accumulation of ODC mRNA was enhanced by the same factor. Concomitantly, the content of the natural polyamines was almost normalized, representing about 65% of that found in the parental cells. The present results suggest that, under a given selection pressure, an overproduction of the target gene product may be primarily based on an enhanced transcriptional activity, possibly associated with hypomethylation and, if not sufficient, a secondary amplification of the active gene occurs.
Full text
PDF




Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Alhonen-Hongisto L., Kallio A., Sinervirta R., Seppänen P., Kontula K. K., Jänne O. A., Jänne J. Difluoromethylornithine-induced amplification of ornithine decarboxylase genes in Ehrlich ascites carcinoma cells. Biochem Biophys Res Commun. 1985 Jan 31;126(2):734–740. doi: 10.1016/0006-291x(85)90246-3. [DOI] [PubMed] [Google Scholar]
- Alhonen-Hongisto L., Leinonen P., Laine R., Jänne J. Human myeloma cells acquire resistance to difluoromethylornithine without overproducing ornithine decarboxylase. Biochem Biophys Res Commun. 1987 Apr 14;144(1):132–137. doi: 10.1016/s0006-291x(87)80485-0. [DOI] [PubMed] [Google Scholar]
- Alhonen-Hongisto L., Seppänen P., Hölttä E., Jänne J. Replacement of natural polyamines by cadaverine and its aminopropyl derivatives in Ehrlich ascites carcinoma cells. Biochem Biophys Res Commun. 1982 May 31;106(2):291–297. doi: 10.1016/0006-291x(82)91108-1. [DOI] [PubMed] [Google Scholar]
- Alhonen-Hongisto L., Sinervirta R., Jänne O. A., Jänne J. Gene expression of ornithine decarboxylase in L1210 leukaemia cells exposed to DL-2-difluoromethylornithine in the presence of cadaverine. Biochem J. 1985 Dec 1;232(2):605–607. doi: 10.1042/bj2320605. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Auffray C., Rougeon F. Purification of mouse immunoglobulin heavy-chain messenger RNAs from total myeloma tumor RNA. Eur J Biochem. 1980 Jun;107(2):303–314. doi: 10.1111/j.1432-1033.1980.tb06030.x. [DOI] [PubMed] [Google Scholar]
- Blin N., Stafford D. W. A general method for isolation of high molecular weight DNA from eukaryotes. Nucleic Acids Res. 1976 Sep;3(9):2303–2308. doi: 10.1093/nar/3.9.2303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hölttä E., Jänne J., Hovi T. Suppression of the formation of polyamines and macromolecules by DL-alpha-difluoromethylornithine and methylglyoxal bis(guanylhydrazone) in phytohaemagglutinin-activated human lymphocytes. Biochem J. 1979 Jan 15;178(1):109–117. doi: 10.1042/bj1780109. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jänne J., Williams-Ashman H. G. On the purification of L-ornithine decarboxylase from rat prostate and effects of thiol compounds on the enzyme. J Biol Chem. 1971 Mar 25;246(6):1725–1732. [PubMed] [Google Scholar]
- Jänne O. A., Kontula K. K., Isomaa V. V., Bardin C. W. Ornithine decarboxylase mRNA in mouse kidney: a low abundancy gene product regulated by androgens with rapid kinetics. Ann N Y Acad Sci. 1984;438:72–84. doi: 10.1111/j.1749-6632.1984.tb38277.x. [DOI] [PubMed] [Google Scholar]
- Kahana C., Nathans D. Isolation of cloned cDNA encoding mammalian ornithine decarboxylase. Proc Natl Acad Sci U S A. 1984 Jun;81(12):3645–3649. doi: 10.1073/pnas.81.12.3645. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kontula K. K., Torkkeli T. K., Bardin C. W., Jänne O. A. Androgen induction of ornithine decarboxylase mRNA in mouse kidney as studied by complementary DNA. Proc Natl Acad Sci U S A. 1984 Feb;81(3):731–735. doi: 10.1073/pnas.81.3.731. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leinonen P., Alhonen-Hongisto L., Laine R., Jänne O. A., Jänne J. Human myeloma cells acquire resistance to difluoromethylornithine by amplification of ornithine decarboxylase gene. Biochem J. 1987 Feb 15;242(1):199–203. doi: 10.1042/bj2420199. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McConlogue L., Dana S. L., Coffino P. Multiple mechanisms are responsible for altered expression of ornithine decarboxylase in overproducing variant cells. Mol Cell Biol. 1986 Aug;6(8):2865–2871. doi: 10.1128/mcb.6.8.2865. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McConlogue L., Gupta M., Wu L., Coffino P. Molecular cloning and expression of the mouse ornithine decarboxylase gene. Proc Natl Acad Sci U S A. 1984 Jan;81(2):540–544. doi: 10.1073/pnas.81.2.540. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Medrano E. E., Burrone O. R., Ferrer M. M., Cafferata E. G., Algranati I. D. A novel mechanism of resistance to alpha-difluoromethylornithine induced by cycloheximide. Growth with abnormally low levels of putrescine and spermidine. FEBS Lett. 1986 Sep 29;206(1):106–110. doi: 10.1016/0014-5793(86)81349-7. [DOI] [PubMed] [Google Scholar]
- Rigby P. W., Dieckmann M., Rhodes C., Berg P. Labeling deoxyribonucleic acid to high specific activity in vitro by nick translation with DNA polymerase I. J Mol Biol. 1977 Jun 15;113(1):237–251. doi: 10.1016/0022-2836(77)90052-3. [DOI] [PubMed] [Google Scholar]
- Schimke R. T. Gene amplification in cultured animal cells. Cell. 1984 Jul;37(3):705–713. doi: 10.1016/0092-8674(84)90406-9. [DOI] [PubMed] [Google Scholar]
- Southern E. M. Detection of specific sequences among DNA fragments separated by gel electrophoresis. J Mol Biol. 1975 Nov 5;98(3):503–517. doi: 10.1016/s0022-2836(75)80083-0. [DOI] [PubMed] [Google Scholar]
- Thomas P. S. Hybridization of denatured RNA and small DNA fragments transferred to nitrocellulose. Proc Natl Acad Sci U S A. 1980 Sep;77(9):5201–5205. doi: 10.1073/pnas.77.9.5201. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Werner D., Chemla Y., Herzberg M. Isolation of poly(A)+ RNA by paper affinity chromatography. Anal Biochem. 1984 Sep;141(2):329–336. doi: 10.1016/0003-2697(84)90050-2. [DOI] [PubMed] [Google Scholar]