Enhancement of methylcholanthrene-induced neoplastic transformation in murine C3H 10T1/2 fibroblasts by antisense phosphorothioate oligodeoxynucleotide sequences

• Published in: Cancer letters 1999-12, Vol.147 (1), p.163-173
• Main Authors: Lesoon-Wood, Leslie A, Pierce, Lisa M, Lau, Alan F, Cooney, Robert V
• Format: Article
• Language: English
• Subjects: Animals; Antisense; Aryl Hydrocarbon Hydroxylases; Base Sequence; Biological and medical sciences; Blotting, Western; Carcinogenesis, carcinogens and anticarcinogens; Carcinogens; Cell Line; Cell Transformation, Neoplastic - chemically induced; Cell Transformation, Neoplastic - drug effects; Chemical agents; Cytochrome P-450 CYP1B1; Cytochrome P-450 Enzyme System - genetics; Dose-Response Relationship, Drug; Enzyme Induction - drug effects; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - enzymology; Interferons - pharmacology; Lipopolysaccharides - pharmacology; Medical sciences; Methylcholanthrene; Mice; Mice, Inbred C3H; Neoplasia; Nitric Oxide - metabolism; Nitric oxide synthase; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Oligonucleotides, Antisense - genetics; Oligonucleotides, Antisense - pharmacology; RNA, Messenger - metabolism; Thionucleotides - genetics; Thionucleotides - pharmacology; Transfection; Tumor Stem Cell Assay; Tumors
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/S0304-3835(99)00292-X

Antisense phosphorothioate oligodeoxynucleotides (ODNs) are increasingly used to target specific proteins for inhibition. Previous reports of antisense inhibition of the inducible nitric oxide synthase (iNOS) gene suggested its utility in defining the role of nitric oxide (NO) in carcinogenesis, as NO is mutagenic and chemical inhibitors of iNOS block neoplastic transformation in C3H 10T1/2 fibroblasts. Treatment with ODNs (0.025–25 μM) directed against 15mer sequences in the iNOS coding region decreased NO production consistent with a reduction of iNOS protein and iNOS mRNA, however, control ODNs (2.5 μM) also showed considerable nonspecific inhibition of NO synthesis. Treatment with both iNOS antisense and mis-sense ODNs during the promotional phase of the C3H10T1/2 transformation assay significantly increased the number of neoplastic foci in 3-methylcholanthrene (MCA) treated cells which corresponded with the ability of the ODN to inhibit NO production. Enhanced neoplastic transformation and non-specific inhibition of NO synthesis resulting from exposure to antisense ODNs suggest limitations to their long-term use in humans at higher doses.