The BPV-4 co-carcinogen quercetin induces cell cycle arrest and up-regulates transcription from the LCR of BPV-4.
Bracken fern is the environmental co-carcinogen of BPV-4 in the induction of neoplasias of the upper alimentary canal of cattle. The flavonoid quercetin is one of the most potent and best characterised mutagens present in the fern. We have shown that transfection with BPV-4 DNA and exposure to a single dose of quercetin leads to tumorigenic transformation of primary bovine cells. We now show that quercetin induces cell cycle arrest and up-regulates transcription from the BPV-4 long control region (LCR). This up-regulation is mediated by a 21 nucleotide-long cis-element in the LCR, designated QRE-1, which is located immediately downstream of the TATA box. Cellular proteins bind to QRE-1 and removal or substitution of QRE-1 lead to the abrogation of the response to quercetin. As expression of the viral oncogenes is controlled by the LCR, perturbation in this control and increased oncoprotein expression are likely to contribute to fully malignant cell transformation by overcoming the cell cycle arrest induced by quercetin, thus forcing damaged cells to proliferate.
Connolly
J A
JA
The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK.
Morgan
I M
IM
Jackson
M E
ME
Campo
M S
MS
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001483:Base Sequence; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D052697:Bovine papillomavirus 4; D002273:Carcinogens / Q000494:pharmacology; D002417:Cattle; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004279:DNA, Viral; D015967:Gene Expression Regulation, Viral / Q000187:drug effects*; D006131:Growth Inhibitors / Q000494:pharmacology; D019901:Locus Control Region / Q000235:genetics*; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011794:Quercetin / Q000494:pharmacology*; D016385:TATA Box; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D002273:Carcinogens; D004279:DNA, Viral; D006131:Growth Inhibitors; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011794:Quercetin; D013755:Tetradecanoylphorbol Acetate