"Oncogenes as Molecular Targets within Active Chromatin."

John H. Frenster,
Physicians' Educational Series, Atherton, CA 94027-5446, USA.
E-mail:  frenster@euchromatin.net

Abstract:
Table: RNA-RNA Duplex Interactions within Chromatin:
Electron Micrograph: DNase I-Sensitive Probes within a Human Leukemia Cell:
Support:
References:
Additional References:
Links:
Feedback:

Abstract:

Active oncogenes play an important role in the pathogenesis of human neoplasms, and are found within the active portion of euchromatin in the cell nucleus (Exp. Cell Res. 93: 484 (1975). Nuclear species of RNA, protein, and lipids are also found at these active sites, and provide possible molecular targets for imaging (Cancer Res. 31: 1128 (1971), for analysis (Nature 248: 334 (1974), and for therapy (Clin. Res. 26: 434A (1978). Nuclear RNA species activate DNA transcription (FASEB J. 13: A1506 (1999), while nuclear protein and lipid have less activity (Nature 206: 680 (1965). Nuclear RNA species can form stable RNA-RNA duplexes (Europ. J. Cancer 11: 117 (1975) that are resistant to RNase, are transmitted to the daughter cells during mitosis, and are more stable to strand-separation than are comparable DNA-DNA duplexes. Single-stranded RNA species have been reported to reverse the human leukemic state (Nature 197: 1077 (1963), and may do so by forming RNA-RNA duplexes with activator RNA at oncogene sites. An analysis of activator RNA at oncogene sites and of the effects of binding such RNA with complementary RNA may provide a form of gene-specific therapy. 

Table 1: RNA-RNA Duplex Interactions within Chromatin:

Table 1: A species of small Antisense RNA can silence gene activity and protein synthesis post-transcriptionally (Science 286: 950 (1999). A species of small Antisense RNA may decrease the transciption of DNA within chromatin (Cancer Res. 36: 3394 (1976). Locus Control Regions of genes are the sites of activity of activators, enhancers, and promoters, and are hyper-sensitive to DNase I digestion (Lewin B, "Genes VII", p. 674-5, Oxford University Press, New York, 2000). Viral and cell oncogenes symmetrically transcribe DNA in-vivo, and the resultant RNAs are self-complementary (Virology 54: 495 (1973). Anti-activator RNA and anti-c-onc RNA are being tested for anti-activity against transcription and oncogenesis, respectively (Ciba Foundation Symposium 209, "Oligonucleotides as Therapeutic Agents", John Wiley & Sons, Inc. Chichester, UK, 1997, pp 94-106 and pp 169-194, respectively).

Electron Micrograph: DNase I-Sensitive Probes within a Human Leukemia Cell:

Electron Micrograph 1: DNase I-Sensitive Probes within a human leukemic bone marrow myeloblast cell. Acridine orange and DNase I-sensitive probe method as described previously (Cancer Res. 31: 1128 (1971).
The electron-dense reaction product is found in the active euchromatin portion of the cell nucleus, and not in the repressed heterochromatin portion nor in the cytoplasm. At this magnification (x 15,000), it may be possible to visualize the extended active euchromatin microfibrils with a hand magnifying glass (x 2), as they course between the large heterochromatin masses of the cell nucleus, but they are best visualized in isolated nuclei after extraction of saline-soluble proteins and RNA in neutral buffers, and resuspension of the nuclei in cation-free 0.25 M sucrose (Nature 205:1341 (1965). The euchromatin microfibrils are 100 A. in diameter, and can be followed for up to 1.0 um. of their length. They are ultrastructurally continuous with the dense fibrils of the heterochromatin masses (Nature 205: 1341 (1965), with a zone of transition of less than 100 A. The DNase I-sensitive probes have diameters of 0.025 um to 0.7 um in size, corresponding to 70-2000 base pairs in DNA helix length (Ann. N.Y. Acad. Sci. 567: 334 (1989), and appear to be asymmetrically distributed within the cell nucleus (Biophys. J. 25: no. 2. part 2, 228a (1979).

Additional References:

"Reversion of Viral-Transformed Neoplastic Cells".

"Electron Micrographs of Reversible Conversion from Heterochromatin to Euchromatin".

"Selective Gene De-Repression by De-Repressor RNA".

Supported in part by USPHS Research Grant CA-10174 from the National Cancer Institute.

References:

1. De La Maza LM, Faras A, Varmus H, Vogt PK, and Yunis JJ, "Integration of Avian Sarcoma Virus-Specific DNA in Mammalian Chromatin", Exp. Cell Res. 93: 484 (1975).

2. Frenster JH, "Electron Microscopic Localization of Acridine Orange Binding to DNA within Human Leukemic Bone Marrow Cells", Cancer Res. 31: 1128 (1971).

3. Nakatsu SL, Masek MA, Landrum S, and Frenster JH, "Activity of DNA Templates during Cell Division and Cell Differentiation", Nature 248: 334 (1974).

4. Frenster JH, Landrum SR, Masek MA, and Nakatsu SL, "DNA Targets for Carcinogens within Living Human Bone Marrow Cells", Clin. Res. 26: 434A (1978).

5. Frenster JH, "Nuclear RNA Species Activate DNA Transcription within Chromatin", FASEB J. 13: no. 7, A1506 (1999).

6. Frenster JH, "Nuclear Polyanions as De-Repressors of Synthesis of Ribonucleic Acid", Nature 206: 680 (1965).

7. Torelli U, Torelli G, and Cadossi R, "Double-Stranded RNA in Human Leukemic Blast Cells", Euro. J. Cancer 11: 117 (1975).

8. DeCarvalho S, "Effect of RNA from Normal Human Bone Marrow on Leukemic Marrow In-Vivo", Nature 197: 1077 (1963).

9. Hamilton AJ, and Boulcombe DC, "A Species of Small Antisense RNA in Posttranscriptional Gene Silencing", Science 286: 950 (1999).

10. Frenster JH, "Selective Control of DNA Helix Openings during Gene Regulation", Cancer Res. 36: 3394 (1976).

11. Lewin B, "Genes", 7th ed., pages 674-5, Oxford University Press, New York, 2000.

12. Aloni Y, and Locker H, "Symmetrical In-Vivo Transcription of Polyoma DNA and the Separation of Self-Complementary Viral and Cell RNA", Virology 54: 495 (1973).

13. Helene C, Giovannangeli C, Guieysse-Peugeot AL, and Praseuth D, "Sequence-Specific Control of Gene Expression by Antigene and Clamp Oligonucleotides", Ciba Foundation Symposium 209, "Oligonucleotides as Therapeutic Agents", pp. 94-106, John Wiley & Sons, Inc. Chichester, UK, 1997.

14. Gewirtz AM, "Oligonucleotide Theraputics for Human Leukemia", Ciba Foundation Symposium 209, "Oligonucleotides as Therapeutic Agents", pp. 169-203, John Wiley & Sons. Inc. Chichester, UK, 1997.

15. Frenster JH, "Ultrastructural Continuity between Active and Repressed Chromatin", Nature 205: 1341 (1965).

16. Frenster JH, "Single-Cell Analysis of DNase I-Sensitive Sites during Neoplastic and Normal Cell Differentiation within Human Bone Marrow", Ann. N. Y. Acad. Sci. 567: 334 (1989).

17. Frenster JH, Papalian MM, Masek MA, and Frenster JA, "Asymmetry of Intra-Nuclear Function during Immune Lymphocyte Activation", Biophys. J. vol. 25, no. 2, part 2, page 228a (1979).

18. Lanz RB, McKenna NJ, Onate SA, Albrecht U, Wong J, Tsai SY, Tsai M-J, and O'Malley BW, "A Steroid Receptor Coactivator, SRA, Functions as an RNA and is Present in an SRC-1 Complex", Cell 97: 17-27 (1999).