Summary of Integration Transcription Analysis in HPV16-Positive Tumors. (F), (R) = Forward or Reverse viral orientation in relation to the cellular gene. Bold text= Viral/cellular fusion transcript, Italicized text=Transcript spans integration site, Grey shade= No transcript produced, a = Nonsense sequence, no alignment, b= Sequence was correct and spliced in frame, c= Sequence mapped to unexpected or rearranged sequences.
ARTICLE ABSTRACT
High-risk HPV (hrHPV) is the leading etiologic factor in oropharyngeal cancer. HPV-positive oropharyngeal tumors generally respond well to therapy, with complete recovery in approximately 80% of patients. However, it remains unclear why some patients are nonresponsive to treatment, with 20% of patients recurring within 5 years. In this study, viral factors were examined for possible clues to differences in tumor behavior. Oropharynx tumors that responded well to therapy were compared with those that persisted and recurred. Viral oncogene alternate transcripts were assessed, and cellular sites of viral integration were mapped and sequenced. Effects of integration on gene expression were assessed by transcript analysis at the integration sites. All of the tumors demonstrated active viral oncogenesis, indicated by expression of HPV E6 and E7 oncogenes and alternate E6 splicing. In the responsive tumors, HPV integration occurred exclusively in intergenic chromosome regions, except for one tumor with viral integration into TP63. Each recurrent tumor exhibited complex HPV integration patterns into cancer-associated genes, including TNFRSF13B, SCN2A, SH2B1, UBE2V2, SMOC1, NFIA, and SEMA6D. Disrupted cellular transcripts were identified in the region of integration in four of the seven affected genes.Implications: Integration of transcriptionally active hrHPV into cellular intergenic regions associates with tumor behavior by altering gene expression. Mol Cancer Res; 14(10); 941–52. ©2016 AACR.
