Ubiquitous presence of E6 and E7 transcripts in human papillomavirus - Positive cervical carcinomas regardless of its type

The presence of human papillomavirus (HPV) DNA in almost all of the cervica l carcinomas is one of the most compelling evidence for the viral carcinoge nesis. HPVs are thought to induce cervical carcinoma most likely through th e expression of E6 and E7 genes presumably by inactivating the tumor suppre ssor proteins, p53 and pRb, respectively. Thus far, the presence of HPV E6 and E7 transcripts have been identified only in cervical carcinoma-derived cell lines harboring type 16 or 18, and in a limited number of cervical neo plasia specimens positive for type 16, 18, 33 or 51. To see whether the exp ression of E6 and E7 genes is an essential finding in HPV-positive cervical carcinoma and cervical intraepithelial neoplasia (CIN), we constructed a r everse transcription-polymerase chain reaction (RT-PCR) assay using a pair of consensus primers in the E6 and E7 regions. Using the assay, E6 transcri pts (full-length E6/E7 transcripts) and E7 transcripts (spliced E6/E7 trans cripts, E6* mRNA) were identified in 97% (30/31) and 100% (all 31) of cervi cal carcinomas and in 100% (all 23) and 74% (17/23) of CINs, respectively. This assay also revealed unknown splice donor and acceptor sites of E6* mRN A of less frequent HPV types 31, 35, 52, 56, 58 and 59 based on sequence an alyses of the PCR products. Thus, the present study demonstrates that E6 an d E7 transcripts of HPV exist in virtually all HPV-positive cervical neopla sia specimens except for the absence of E7 transcripts in some of CINs. (C) 2000 Wiley-Liss, Inc.