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Transcriptional profiling of an HPV 33 positive squamous epithelial cell line with either episomal or integrated form of the virus.Department of Oral Radiology and Pathology, Institute of Dentistry and Medicity Research Laboratory, University of Turku, FIN - 20520 Turku, FinlandAIM: Alterations in gene expression represent a key event in carcinogenesis. We have studied human papillomavirus (HPV)-induced cervical carcinogenesis, using an HPV 33-positive cell line (UT-DEC-1) established from a low-grade vaginal dysplasia (VAIN I). Early passage cells contained HPV 33 in episomal form, but these were superseded at later passages by cells carrying only integrated virus. To get insights into the biological significance of HPV integration, we compared the levels of gene expression in normal vaginal keratinocytes, early passage- and late passage UT-DEC-1 cells, using cDNA microarrays. METHODS: Total RNA was isolated from the cells by CsCl-gradient centrifugation. An aliquot of 5 mg of total RNA was used in the microarray analysis, performed according to Clontechs Human Cancer 1.2 cDNA expression array kit manual. Total RNA was reverse transcribed with MMLV reverse transcriptase and labeled with a-32P ATP. RESULTS: The 15 up-regulated genes identified by comparing both cell types to control keratinocytes and using a two-fold cut-off, seem to support cell cycle progression or are functional in mitosis. These include e.g. MCM4 DNA replication licensing factor, cdc2p34 and chromatin assembly factor 1 p48 subunit. Down-regulated genes (45 altogether) interfere with apoptosis and cell adhesion, including the apoptosis inducing genes FRAP, Bik and caspase-9 precursor. The most significant differences between the late and early passages (30 up and 46 down), were over-expression of the transcription factors E2F5 with its dimerization partner DP1, NF-kB, and serine/threonine kinases, and under-expression of enzymes of the MAP kinase pathway. CONCLUSIONS: The acquisition of selective growth advantage after viral integration might be explained by a major shift from a MAP kinase pathway to cell cycle dysregulation (G2/M). For more information, contact stina.syrjanen@utu.fi Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Viral Oncogenesis. |
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