ヒトパピローマウイルスと癌

抄録

More than twenty genotypes of human papillomaviruses (HPVs) are associated with mucosal lesions and more than thirty genotypes with cutaneous lesions. We established a method using consensus polymerase chain reaction (PCR) with restriction endonuclease analysis of PCR products, which can detect and distinguish mucosal high risk HPV types 16, 18, 31, 33, 52b and 58 (J. Gen. Virol. 72, 1039, 1991). By using this method, we analyzed 39 cases of cervical carcinomas and 27 cases of cervical intraepithelial neoplasias (CIN). It was found that the HPV16 was most prevalent in malignant (19 cases) and premalignant (19 cases) cervical lesions, but other types including HPV18, 31, 33, 52b and 58 were also detected especially in cervical carcinomas. We also established a highly sensitive method for specific detection of HPV types 16, 18, and 33 (Jpn. J. Cancer Res., 81, 1, 1990) . The method detected HPV16 DNA in only 5 out 92 cases of cytologically or histologically normal cervices (Jpn. J. Cancer Res., 82, 532, 1991) . HPV16 was also predominantly detected in penile (68 out of 111 cases) and tongue (8 out of 24 cases) squamous cell carcinomas.
HPV16 E6E7 region produces at least three different species of E6E7 mRNAs (unspliced E6-E7, spliced E6* I and E6* II) in the HPV16-containing carcinoma cells. We synthesized each of the E6E7 cDNAs and studied on their biological activities. The E6*I cDNA showed highest activities of ras-collaborative transformation of primary rat fibroblasts and induction of cellular DNA synthesis. We analyzed HPV16 E6E7 mRNAs in three cervical carcinomas and six CINs which contained HPV16 DNA by PCR with reverse transcription (RT-PCR) . The major transcript from HPV16 E6E7 region was E6* I except for one CIN tissue where only the full-length E6-E7 mRNA was detected.
Different from E7 genes of mucosal high-risk HPVs, E7 genes of HPV5 and HPV8, which are associated with epidermodysplasia verruciformis (EV) were inactive for transforming ability in cell lines. We cloned HPV5 and 8 E7s separately into the expression vector pcD2Y or pGEM3Zf and examined their biological and biochemical activities. Although HPV5 and 8 E7s failed to immortalize primary baby rat kidney cells, they collaborated with activated ras gene to transform primary rat embryo fibroblasts (Jpn. J. Cancer Res., 82, 1340, 1991) and baby rat kidney cells. In vitro binding experiment of retinoblastoma tumor suppressor protein (RB) detected the complex formation of HPV5 and 8 E7s with RB but with reduced affinities compared to HPV16 E7.