Sites of disruption within E1 and E2 genes of HPV16 and association with cervical dysplasia

Abstract

Integration of HPV16 DNA into the host chromosome usually disrupts the E1 and/or E2 genes. The present study investigated the disruption of E1, E2 genes in a total of eighty four HPV16-positive precancerous and cervical cancer specimens derived from Greek women (seventeen paraffin-embedded cervical biopsies and sixty seven Thin Prep samples). Complete E2 and E1 genes were amplified using three and nine overlapping primer sets respectively, in order to define the sites of disruption. Extensive mapping analysis revealed that disruption/deletion events within E2 gene occurred in high grade and cervical cancer samples (x(2) test, P < 0.01), while no evidence of E2 gene disruption was documented among low grade cervical intraepithelial neoplasias. In addition, disruptions within the E1 gene occur both in high and low grade cervical intraepithelial neoplasia. This leads to the assumption that in low grade cervical intraepithelial neoplasias only E1 gene disruption was involved (Fisher's exact test, P < 0.05), while in high grade malignancies and cervical cancer cases deletions in both E1 and E2 genes occurred. Furthermore, the most prevalent site of disruption of E1 gene was located between nucleotides 1059 and 1323, while the most prevalent deleted region of the E2 gene was located between nucleotides 3172 and 3649 (E2 hinge region). Therefore, it is proposed that each population has its own profile of frequencies and sites of disruptions and extensive mapping analysis of E1 and E2 genes is mandatory in order to determine suitable markers for HPV16 DNA integration analysis in distinct populations.

HPV16 integration probably contributes to cervical oncogenesis through interrupting tumor suppressor genes and inducing chromosome instability

“…Although HPV16 and 18 are considered to be the most prevalent HPV types contributing to cervical cancers worldwide, HPV18 is not the most common genotype in Asian countries and our previous results suggested that HPV16 and 52, instead of HPV18, are the top two prevalent types in Shanghai women [3–6]. The viral DNA is usually found to integrate into the host genome with subsequent disruption of one or more viral open reading frames (ORFs) [7]. HPV integration frequently disrupts in the E1 and/or E2 ORFs.…”

E1 Detection as Prognosticator in Human Papillomavirus-Positive Head and Neck Cancers

“…The E6 gene may be present in both episomal and integrated forms, playing a key role in malignant transformation (15), or may remain just as a persistent and harmless DNA fragment after a resolved infection (16,35). Integration usually hits other, less attractive targets at different sites in E1, E2, L1 and L2 regions (10,14,20,21,36) and potentially reduces the sensitivity in HPV detection (37).…”

“…The reverse primers were constructed for each fragment in order to get smaller fragments from FFPE tissues (80 bp for E6 and 97 bp for L1). E1 primers were designed inside the coding region, most frequently disrupted during viral integration in the host chromosome (14,32), in order to get a fragment of 168 bp.…”

E1 and E2 Viral Proteins as Therapeutic Targets for Development of Antiviral Agents

“…It has been demonstrated clearly that expression E1 and E2 proteins from different HPV genomes can induce replication of the genomic integrated HPV origin [30], and this is a particular danger in the presence of DNA damage [31]. Then, anti-HPV agents unblocking viral DNA synthesis could, in time, benefit cancer development increasing HPV genome integration.…”