Shimabuku Tetsuya, Tamanaha Ayumi, Kitamura Bunta, Tanabe Yasuka, Tawata Natsumi, Ikehara Fukino, Arakaki Kazunari, Kinjo Takao
Division of Morphological Pathology, Department of Basic Laboratory Sciences, School of Health Sciences, University of the Ryukyus Japan.
The Department of Pathology and Cell Biology, Graduate School of Medicine, University of the Ryukyus Japan.
Int J Clin Exp Pathol. 2014 Apr 15;7(5):1920-34. eCollection 2014.
The prevalence of Epstein-Barr virus (EBV) and high-risk human papilloma virus (HPV) infections in patients with oral cancer in Okinawa, southwest islands of Japan, has led to the hypothesis that carcinogenesis is related to EBV and HPV co-infection. To explore the mechanisms of transformation induced by EBV and HPV co-infection, we analyzed the transformation of primary mouse embryonic fibroblasts (MEFs) expressing EBV and HPV-16 genes, alone or in combination. Expression of EBV latent membrane protein-1 (LMP-1) alone or in combination with HPV-16 E6 increased cell proliferation and decreased apoptosis, whereas single expression of EBV nuclear antigen-1 (EBNA-1), or HPV-16 E6 did not. Co-expression of LMP-1 and E6 induced anchorage-independent growth and tumor formation in nude mice, whereas expression of LMP-1 alone did not. Although the singular expression of these viral genes showed increased DNA damage and DNA damage response (DDR), co-expression of LMP-1 and E6 did not induce DDR, which is frequently seen in cancer cells. Furthermore, co-expression of LMP-1 with E6 increased NF-κB signaling, and the knockdown of LMP-1 or E6 in co-expressing cells decreased cell proliferation, anchorage independent growth, and NF-κB activation. These data suggested that expression of individual viral genes is insufficient for inducing transformation and that co-expression of LMP-1 and E6, which is associated with suppression of DDR and increased NF-κB activity, lead to transformation. Our findings demonstrate the synergistic effect by the interaction of oncogenes from different viruses on the transformation of primary MEFs.
在日本西南岛屿冲绳县的口腔癌患者中，爱泼斯坦-巴尔病毒（EBV）和高危型人乳头瘤病毒（HPV）感染的高发生率引发了这样一种假说，即致癌作用与EBV和HPV的共同感染有关。为了探究EBV和HPV共同感染诱导细胞转化的机制，我们分析了单独或联合表达EBV和HPV-16基因的原代小鼠胚胎成纤维细胞（MEF）的转化情况。单独表达EBV潜伏膜蛋白-1（LMP-1）或与HPV-16 E6联合表达均能增加细胞增殖并减少细胞凋亡，而单独表达EBV核抗原-1（EBNA-1）或HPV-16 E6则不能。LMP-1和E6的共同表达诱导了裸鼠的锚定非依赖性生长和肿瘤形成，而单独表达LMP-1则不能。尽管这些病毒基因的单独表达显示DNA损伤和DNA损伤反应（DDR）增加，但LMP-1和E6的共同表达并未诱导在癌细胞中常见的DDR。此外，LMP-1与E6的共同表达增加了NF-κB信号传导，在共同表达的细胞中敲低LMP-1或E6会降低细胞增殖、锚定非依赖性生长和NF-κB激活。这些数据表明，单个病毒基因的表达不足以诱导细胞转化，而LMP-1和E6的共同表达与DDR的抑制和NF-κB活性的增加相关，从而导致细胞转化。我们的研究结果证明了来自不同病毒的癌基因相互作用对原代MEF转化的协同作用。
