Identification and functional analysis of sequence rearrangements in the long control region of human papillomavirus type 16 Af-1 variants isolated from Ugandan penile carcinomas.
Human papillomavirus type 16 (HPV-16) is the predominant HPV isolate found in malignancies of male and female lower genital tracts. However, only a small percentage of individuals infected with high-risk HPVs develop a genital neoplasia, suggesting that additional events at both the cellular and the virus level are necessary for the progression to cancer, including genetic mutations/rearrangements of viral sequences involved in the oncogenic process. In this study, the genetic stability of the long control region (LCR) (nt 7289-114), which regulates expression levels of oncoproteins E6 and E7, was analysed in HPV-16 isolates from penile carcinoma (PC) biopsies of patients recruited from Uganda, one of the countries with the highest incidence of genital cancers in both men and women. Nucleotide changes within the LCR region typical of the African-1 (Af-1) lineage were observed in all HPV-16 isolates. Two out of five samples showed further rearrangements of the enhancer region. The functional activity of LCR with Af-1 mutations and/or rearrangements was evaluated by cloning each LCR into CAT expression vectors, followed by transfection in several epithelial and non-epithelial cell lines. CAT expression levels driven by a rearranged LCR were significantly higher than those driven by Af-1 or European prototype LCRs. Furthermore, in the NIH3T3 focus formation assay, the transforming activity of E6 and E7 genes, driven by a mutated or rearranged LCR, was 1.4- to 3.0-fold higher, respectively. These results indicate that rearrangements within the LCR of HPV-16 isolated from African PCs are frequently found (2 out of 5, 40%). It is also shown that increased HPV LCR activity is associated with an increased E6/E7-mediated in vitro transforming activity, suggesting that natural variants can play a major role in the pathogenesis of genital carcinomas.
Tornesello
Maria Lina
ML
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
Buonaguro
Franco M
FM
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
Buonaguro
Luigi
L
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
Salatiello
Immacolata
I
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
Beth-Giraldo
Elke
E
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
Giraldo
Gaetano
G
Division of Viral Oncology and AIDS Reference Center, National Cancer Institute 'Fondazione Pascale', Mariano Semmola 1, I-80131 Naples, Italy1.
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics; D004847:Epithelial Cells / Q000821:virology; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter / Q000235:genetics; D005814:Genes, Viral / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics*; D006801:Humans; D015994:Incidence; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009856:Oncogene Proteins, Viral / Q000235:genetics; D027383:Papillomaviridae / Q000235:genetics* / Q000302:isolation & purification* / Q000472:pathogenicity; D050725:Papillomavirus E7 Proteins; D010412:Penile Neoplasms / Q000453:epidemiology / Q000821:virology*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012097:Repressor Proteins; D016415:Sequence Alignment; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay; D014454:Uganda / Q000453:epidemiology
D004279:DNA, Viral; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16