Preferential integration of human papillomavirus type 18 near the c-myc locus in cervical carcinoma

Abstract

The development of cervical cancer is highly associated with human papillomavirus (HPV) infection. Greater than 99% of all cervical tumors contain HPV DNA. Integration of high-risk HPV has been temporally associated with the acquisition of a malignant phenotype. Recent work from our lab has shown that HPV16, the most common high-risk HPV associated with cervical carcinoma, preferentially integrates at loci containing human common fragile sites (CFSs). CFSs are regions of genomic instability that have also been associated with deletions, translocations, and gene amplification during cancer development. The current work shows that HPV18, the second most prevalent highrisk HPV type found in cervical tumors, preferentially targets the CFSs. We identified 27 unique HPV18 integrations in cervical tumors, of which 63% (Po0.001) occur in CFSs. However, the distribution of HPV18 integrations found were profoundly different from those found for HPV16. Specifically, 30% of all HPV18 integrations occurred within the chromosomal band 8q24 near the c-myc proto-oncogene. None of the HPV16 integrations occurred in this region. Previous low-resolution mapping suggested that c-myc may be a target of HPV integration. Our data at nucleotide resolution confirm that in HPV18-positive cervical tumors, the region surrounding c-myc is indeed a hot spot of viral integration. These results demonstrate that CFSs are preferred sites of integration for HPV18 in cervical tumors. In addition, we have identified multiple cellular genes that have been disrupted by HPV18 integration in cervical tumors. Our results suggest that the sites of HPV18 integration are nonrandom and may play an important role in the development of cervical tumors.

MYC activation associated with the integration of HPV DNA at the MYC locus in genital tumors

“…HPV18 is frequently associated with adenocarcinoma (Lombard et al, 1998) and preferentially integrates at the MYC locus (Ferber et al, 2003b). However, we and others (Brink et al, 2002;Wentzensen et al, 2002) have also found HPV16 DNA at this locus.…”

“…It is important to underline that, comparing the histological type of cervical carcinomas, when it was documented, to the cartography of viral integration sites (present study and (Thorland et al, 2000;Klimov et al, 2002;Ferber et al, 2003b), 9/10 cases with HPV DNA sequences at the MYC locus corresponded to adenocarcinomas, whereas 22/29 of cases with viral sequences at other sites were squamous cell carcinoma (P ¼ 4.10 À4 ). HPV18 is frequently associated with adenocarcinoma (Lombard et al, 1998) and preferentially integrates at the MYC locus (Ferber et al, 2003b).…”

“…Up to 181 different sites corresponding to 243 cases have been observed (Brink et al, 2002;Klimov et al, 2002;Wentzensen et al, 2004;Kraus et al, 2005;and our unpublished results). In spite of this scattering, it is remarkable that the chromosome band 8q24, to which MYC maps, is the most recurrent site for insertion of HPV DNA, as it is found in 10.7% (26/243) of the all cases (Du¨rst et al, 1987;Popescu et al, 1987;Couturier et al, 1991;Hori et al, 1991;Brink et al, 2002;Wentzensen et al, 2002;Ferber et al, 2003b;Ziegert et al, 2003;Kraus et al, 2005). A low level of MYC overexpression has been found in HeLa cells harboring HPV18 sequences in chromosome band 8q24 (Du¨rst et al, 1987;Lazo et al, 1989), but no evidence of MYC activation directly related to HPV insertion at the MYC locus has been published.…”

“…Besides MYC, a number of genes, potentially involved in carcinogenesis, such as CEACAM5, FANCC (Wentzensen et al, 2002;Ferber et al, 2003b), TP63 (Wentzensen et al, 2002), TERT (Ferber et al, 2003a), MYOF, Ribosomal protein gene RPS27 (Klimov et al, 2002), MYCN (Sastre-Garau et al, 2000), NFIB (Ziegert et al, 2003), have also been found to correspond to targets for the insertion of HPV DNA. In spite of this diversity, only a few cases with an integration pattern compatible with a mechanism of insertional mutagenesis have been observed (Wentzensen et al, 2002).…”

“…These data suggest that MYC activation could be secondary to the insertion of HPV DNA sequences at the MYC locus. Although a large diversity of integration sites has been reported (Wentzensen et al, 2004), MYC chromosome region is the most recurrent localization for HPV insertion, found in about 10% of genital neoplasias, observed in chromosome band 8q24 by fluorescence in situ hybridization (FISH) (Du¨rst et al, 1987;Couturier et al, 1991;Hori et al, 1991;Brink et al, 2002) or at the MYC locus by DNA/RNA analysis (Wentzensen et al, 2002;Ferber et al, 2003b;Ziegert et al, 2003;Kraus et al, 2005). However, despite this recurrence, no evidence of MYC overexpression directly associated with the insertion of HPV DNA at the MYC locus has been shown so far.…”