Correlation between Tumorigenicity and Expression Levels or Splicing Patterns of Transcripts of the Human Papillomavirus Type 16 E6 Gene

For determination of the correlation between tumorigenicity and the expression levels or splicing patterns of E6 mRNAs of the human papillomavirus type 16 in established cells, a vector containing the intact E6 open reading frame which expresses both unspliced and spliced mRNAs, one expressing only unspliced E6 mRNA, and one expressing both unspliced and spliced mRNAs but producing only truncated E6 proteins were constructed. In transformation assays and analyses of E6 mRNAs, a higher expression level of unspliced E6 mRNA was found to be closely associated with tumorigenicity. Furthermore, it was also related with anchorage‐independent growth and a decreased serum requirement of the cells.