PARENT SESSION
1:30 PM to 3:30 PM
Tuesday, April 23, 2002
Poster Session 17 Induced Gene Expression
Room: Nevada Exhibition Center

(P22-243) Identification of Apoptosis and Cell Cycle Regulatory Genes by Expression Profiling Using cDNA Arrays .

Oancea, Marcela^*,1,2, Stanhope-Baker, Patricia², Frevel, Mathias², Agarwal, Munna³, Williams, Bryan³, Almasan, Alex^1,2, ¹ Department of Radiation Oncology, Cleveland, Ohio² Department of Cancer Biology, Cleveland, Ohio³ Department of Molecular Biology, Cleveland, Ohio

ABSTRACT-
The transcriptional response to ionizing radiation is not well understood. The IM-9 multiple myeloma cell line has been used in our laboratory as a model system to investigate the role of cell cycle regulators in apoptosis. Cyclin E (cyc E), regulates the G1/S transition by interacting with its catalytic partner, the cyclin-dependent kinase 2 (CDK2) to control the activity of an associated kinase. Following ionizing radiation (IR), Cyclin E is induced transcriptionaly in several hematopietic tumor cell lines, including IM-9. Forced cyc E expression sensitizes cells to radiation; in contrast, inhibition of Cyc E/Cdk2 kinase activity by a dominant negative Cdk2 (DnCdk2) or the anti-apoptotic gene Bcl-2 prevents it. To get a better understanding of the role of cell cycle regulatory genes in radiation-induced apoptosis, we are using expression profiling with oligonucleotide and cDNA arrays. As a proof of principle, we have examined the response of IM-9 cells and their derivatives overexpressing DnCdk2 and Bcl-2, which are resistant to radiation-induced apoptosis. A custom-made array was constructed with 2,600 cDNAs and ESTs, which were selected as putative p53-regulated genes and cDNAs, which we have identified by oligonucleotide (Affymetrix) array experiments to be regulated in irradiated cells. The array was assembled from clones contained in the Genetics Research libraries and printed on glass slides. Preliminary experiments indicate that fewer genes are induced in those cells which do not undergo apoptosis, indicating that gene expression is required for this process. In addition, a different set of genes, including some not previously characterized, were induced in the three cell lines. The kinetics of expression of these genes is currently validated by conventional molecular approaches. Supported by CA 81504 and CA 82858.

KEYWORDS: apoptosis, cell cycle, gene expression, expression profiling