Xu Feng, Cao Meng, Shi Qinfeng, Chen Hongwei, Wang Yili, Li Xu
Center for Translational Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, 277# YanTaXiLu, Xi'an, 710061, Shaanxi, China.
Virus Genes. 2015 Apr;50(2):210-20. doi: 10.1007/s11262-014-1164-7. Epub 2015 Feb 10.
Integration of high-risk human papillomavirus (HPV) into the host genome is a key event for cervical carcinogenesis. Different methods have been used to explore the physical states of the HPV genome to reveal the mechanisms for malignant transformation of the infected cells. Consensus has been reached that, although variable portions of the HPV genome are deleted in the integrated HPV sequences, common disruption of the viral E2 gene has been demonstrated in different studies. The head-to-tail concatemers of the full-length HPV16 genome is another typical integration pattern of HPV16, typically found in Caski cell lines, but its prevalence in cervical cancer has never been tested. Here, by introducing a modified PCR, we identified this head-to-tail concatemers of full-length HPV genomes in advanced cervical cancer with HPV16 single positive. Our results show that more than half of the cases contain this integrated head-to-tail concatemers of full-length HPV16 genomes. Further studies in two cervical cell lines, Caski cells and Siha cells, revealed a correlation between the prevalence of the spliced variants of integrated HPV16 sequences and the full-length transcription of the integrated head-to-tail concatemers of the full-length HPV16 genome. Based on these results, we propose that HPV16 integrated into host cells by two mechanisms: one mechanism is shared by other DNA virus and cause integration of the head-to-tail concatemers of the viral genome; another is related to the reverse transcription process, which the integrated HPV sequence is generated by the reverse transcription of the viral mRNA.
高危型人乳头瘤病毒（HPV）整合至宿主基因组是宫颈癌发生的关键事件。人们运用不同方法探索HPV基因组的物理状态，以揭示受感染细胞发生恶性转化的机制。目前已达成共识，尽管整合的HPV序列中HPV基因组的可变部分会缺失，但不同研究均证实病毒E2基因通常会被破坏。全长HPV16基因组的头对头串联体是HPV16另一种典型的整合模式，通常在Caski细胞系中发现，但其在宫颈癌中的发生率从未得到检测。在此，我们通过引入改良的PCR技术，在HPV16单阳性的晚期宫颈癌中鉴定出了全长HPV基因组的这种头对头串联体。我们的结果显示，超过半数的病例含有这种整合的全长HPV16基因组头对头串联体。在两种宫颈癌细胞系Caski细胞和Siha细胞中的进一步研究揭示，整合的HPV16序列剪接变体的发生率与全长HPV16基因组整合头对头串联体的全长转录之间存在相关性。基于这些结果，我们提出HPV16通过两种机制整合至宿主细胞：一种机制与其他DNA病毒相同，导致病毒基因组头对头串联体的整合；另一种机制与逆转录过程有关，即整合的HPV序列由病毒mRNA逆转录产生。
