Angelo Rosolen

Antisense inhibition of gene expression: a tool for studying the role of NMYC in the growth and differentiation of neuroectoderm-derived cells.

Summary: To understand the role of individual genes in regulating biological processes, one must be able to interfere specifically with either their expression or function. While monoclonal antibodies have proven very useful in studying cell surface proteins, the specific inhibition of intracellular proteins in viable cells is a much more difficult problem. The goal of antisense technology is to develop small oligonucleotides, plasmids, or retroviral vectors that can be introduced easily into viable cells in order to inhibit gene products specifically. In this report, we will describe our use of antisense DNA and RNA to study the role of the NMYC proto-oncogene in neuroectodermal cell growth and differentiation.

Specific Inhibition of Oncogene Expression in Vitro and in Vivo by Antisense Oligonucleotides

To understand the role of individual genes in regulating biological processes, one must be able to interfere specifically with either their expression or their function. Although monoclonal antibodies have proven very useful in studying cell surface proteins, the specific inhibition of intracellular proteins in viable cells is a much more difficult problem. The goal of antisense technology is to develop small oligonucleotides, plasmids, or retroviral vectors that can be introduced easily into viable cells to specifically inhibit gene products. This report describes our use of antisense DNA and RNA to study the role of the NMYC protooncogene in neuroectodermal cell growth and differentiation and to begin to assess the potential of in vivo antisense oligonucleotide administration as gene-targeted therapy. NMYC is a DNA-binding phosphoprotein of unknown function. Unlike its homolog, MYC, NMYC expression is temporally regulated and is limited to immature T and B lymphocytes, fetal tissues, and various tumors of neuroendocrine origin, such as neuroblastoma, neuroepithelioma, retinoblastoma, small cell lung carcinoma, and Wilms’ In neuroblastoma, NMYC copy number is consistent in tumor biopsies obtained from individual patients over time, whereas NMYC expression may vary. Thus, NMYC gene amplification is an intrinsic property of a subset of these tumors and does not occur with progressive disease if it is not present at diagnosis. However, the development of progressive disease is likely to occur in patients with amplified or overexpressed N I W C . ~ The transient and localized expression of NMYC during the early stages of organogenesis, together with the presence of conserved motifs characteristic of transcription factors, suggests that NMYC may regulate gene expression in the developing o rgan i~m.~-~