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Series GSE4289

Query DataSets for GSE4289

Status

Public on Feb 24, 2006

Title

Host transcriptome changes associated with episome loss and selection of keratinocytes containing integrated HPV16

Organism

Homo sapiens

Experiment type

Expression profiling by array

Summary

Integration of high-risk human papillomavirus (HRHPV) into the host genome is a key event in cervical neoplastic progression. Integration is associated with deregulated expression of the viral oncogenes E6 and E7 and acquisition of a selective growth advantage for cells containing integrants. Overexpression of the viral transcriptional regulator E2 from heterologous promoters has an inhibitory effect on transcription from integrated HRHPV. We therefore hypothesised that loss of E2-expressing episomes from cells in which integration had previously occurred would be required for such cells to gain a growth advantage. Using the unique W12 model of cervical squamous carcinogenesis, we show that cells containing integrated HPV16 reproducibly emerged during long-term culture when there had been a rapid fall in episome numbers. During the period of emergence it is possible to isolate single-cell clones containing an intracellular mixture of the integrant being selected and episomes at reduced load. Microarray analysis showed that episome loss was closely associated with endogenous activation of antiviral response genes that are also inducible by the type I interferon (IFN) pathway. Taken together, our results indicate that episome loss, associated with induction of antiviral response genes, is a key event in the spontaneous selection of cervical keratinocytes containing integrated HPV16. We conclude that cervical carcinogenesis requires not only HRHPV integration, but also loss of inhibitory episomes.
Keywords: Time course, human papillomavirus, episome loss

Overall design

The overall aim was to determine host gene expression changes associated with episome loss in W12 cells undergoing selection for integrated HPV16. We therefore compared gene expression in W12 populations representing different stages in the process of integrant selection. We compared W12p10EPI (episome-only) with clones W12.MRP20 (undergoing selection for the integrant and episome loss) and W12.MRP29 (containing only the selected integrant), which are henceforth referred to as W12.MRP20MIX and W12.MRP29INT. These three conditions were treated as a time-course.

Preparation and hybridisation of probes for microarray analysis: Total RNA from W12 samples was used to generate biotin-labelled cRNA for microarray analysis. Two technical replicates were performed for each sample to control for variation in labelling and hybridisation efficiency. Double-stranded cDNA was synthesised using SuperScript (Invitrogen), employing the (dT)24-T7 promoter primer. Biotin-labelled cRNA was then generated by Bioarray in vitro transcription (Enzo), and fragmented by metal-induced hydrolysis. Probe from each replicate was hybridised, washed, stained and scanned by the Medical Research Council Geneservice (Cambridge, UK) using standard Affymetrix procedures. We used GeneChip HG-U133 Plus 2.0 Arrays (Affymetrix). MAS 5.0 transformation of raw data was performed and further statistical analysis carried out using GeneSpring (Agilent Technologies). Real-time RT-PCR of cDNA was performed to validate changes in expression of selected host genes.

Contributor(s)

Pett MR, Herdman MT, Palmer RD, Yeo GS, Shivji MK, Stanley MA, Coleman N

Citation(s)

16505361

Submission date

Feb 22, 2006

Last update date

Mar 25, 2019

Contact name

Mark Robert Pett

E-mail(s)

mrp20@mole.bio.cam.ac.uk