Transcriptional Patterns of High-Risk Human Papillomavirus Types 16, 18, 45, 68b Genes

Arkom Chaiwongkot, Masahide Seki, Yutaka Suzuki, Teerasit Techawiwattanaboon and Parvapan Bhattarakosol

Background and Objective: Persistent high-risk human papillomavirus (HR-HPV) infections together with their oncogene expressions are necessary for cervical cancer development. We aimed to detect transcription patterns and the major viral oncogene transcripts expressed in five cervical cancer cell lines containing integration form of four HR-HPV types 16, 18, 45 and 68b. Materials and Methods: RNA extracted from five cervical cancer cell lines (CaSki, SiHa, HeLa, MS751 and ME180) were used for RNA sequencing analysis on an Illumina HiSeq2500. The HISAT2, Cufflinks, Cuffmerge and Cuffdiff were used to analyze the data. The HPV transcripts were quantified as fragments per kilobase per million (FPKM). Real-time PCR was performed to validate and differential viral gene expressions. Results: The major and common transcripts obtained from four HR-HPV types 16, 18, 45 and 68b were E6*I with splicing event occur within the E6 gene fused with full-length E7 ORF, 226^409 (HPV16), 233^416 (HPV18), 230^412 (HPV45) and 129^311(HPV68b) and were associated with full-length E7 oncogene expression. Real-time PCR revealed that full-length HR-HPV E7 oncogene was highly expressed in all five cell lines. Conclusion: Splicing patterns that occurred within the E6 gene resulting in the E6*I transcript facilitates E7 oncogene translation. Various transcripts obtained from four HR-HPV types are useful for further functional study of truncated viral proteins expressed from different HPV types.

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