Transcription of human papillomavirus type 16 early genes in a cervical cancer and a cancer-derived cell line and identification of the E7 protein.

TLDR

HPV16 DNA and RNA were characterized in the CaSki cervical cancer cell line, which contains only integrated viral DNA, and in a cervical cancer sample that mainly harbors plasmid DNA. Both CaSki cells and cervical cancer express a major RNA encoding E7 and a minor RNA encoding E6, but only the cervical cancer contains a minor RNA for intact E2, and the presence of E7 protein in CaSki cells suggests it may contribute to malignant progression or maintenance.

Abstract

Human papillomavirus type 16 DNA and RNA were characterized in the cervical cancer-derived CaSki cell line, which contains only integrated DNA, and in a cervical cancer, which contains predominantly plasmid DNA. In both, a major RNA can code for the early open reading frame E7 and a minor one can code for E6. The cervical cancer, but not the CaSki cell line, contains a minor RNA that can code for an intact E2 protein, and this may relate to the continued presence of plasmid DNA. The RNA mapping data suggest that the poly(A)+ RNA is transcribed from a minor fraction of the several hundred gene copies present, and in the cervical cancer these genomes appear to be integrated. The E7 protein has been identified in CaSki cells and the prevalence of its mRNA suggests a possible function in progression to, or long-term maintenance of, the malignant state.