Jin Yu, Li Yuexiu, Wang Xin, Yang Ya
1Department of General Dentistry, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011 P. R. China.
Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, National Clinical Research Center of Stomatology, Shanghai, 200000 P. R. China.
Cancer Cell Int. 2019 Aug 23;19:220. doi: 10.1186/s12935-019-0942-7. eCollection 2019.
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and human papillomavirus (HPV) has been increasingly recognized as a pathogenic factor for the initiation and development of HNSCC. E6 oncogene, an essential component of the HPV 16 virus, acts as a leading cause of the malignant transformation of cancer cells. Therefore, investigating the biological effect and potential mechanisms of E6 oncogene on HNSCC cells and exploring potential therapeutic methods is of great value.
MTT assay, cell cycle analysis, and apoptosis assay were implemented to detect the biological effect of E6 oncogene on the growth of HNSCC cells. Wound healing assay and transwell assay were used to evaluate the role of E6 in the migration and invasion of HNSCC cells. Western blot and immunofluorescence assay were adopted to explore the regulatory mechanisms underlying E6-induced HNSCC progression. Then, exogenous secretory leukocyte protease inhibitor (SLPI) was added into the cell culture to investigate whether it could maintain its tumor suppressor effect on E6-expressing HNSCC cells.
HPV E6 oncogene could promote the proliferation, cell cycle period, apoptosis resistance, migration and invasion of HNSCC cells by activating NF-κB and Akt pathways. Immunohistochemical analysis conducted on HNSCC tissues illustrated that SLPI was further downregulated in HPV positive HNSCC compared to HNSCC without HPV infection. Exogenous SLPI significantly inhibited HPV E6-mediated malignant phenotypes in HNSCC cells by inhibiting the activation of NF-κB and Akt and signaling pathways.
This study demonstrated that E6 oncogene led to the malignant transformation of HNSCC cells by regulating multiple pathways. SLPI could reverse the effect of E6 oncogene on HNSCC, implying that the functional inhibition of E6 by SLPI may be exploited as an attractive therapeutic strategy.
头颈部鳞状细胞癌（HNSCC）是全球第六大常见癌症，人乳头瘤病毒（HPV）已越来越被认为是HNSCC发生和发展的致病因素。E6癌基因是HPV 16病毒的重要组成部分，是癌细胞恶性转化的主要原因。因此，研究E6癌基因对HNSCC细胞的生物学效应和潜在机制，并探索潜在的治疗方法具有重要价值。
采用MTT法、细胞周期分析和凋亡检测来检测E6癌基因对HNSCC细胞生长的生物学效应。采用伤口愈合试验和Transwell试验评估E6在HNSCC细胞迁移和侵袭中的作用。采用蛋白质免疫印迹法和免疫荧光试验探讨E6诱导HNSCC进展的调控机制。然后，将外源性分泌型白细胞蛋白酶抑制剂（SLPI）加入细胞培养物中，研究其是否能对表达E6的HNSCC细胞保持其肿瘤抑制作用。
HPV E6癌基因可通过激活NF-κB和Akt信号通路促进HNSCC细胞的增殖、细胞周期进程、抗凋亡、迁移和侵袭。对HNSCC组织进行的免疫组织化学分析表明，与未感染HPV的HNSCC相比，HPV阳性的HNSCC中SLPI进一步下调。外源性SLPI通过抑制NF-κB和Akt信号通路的激活，显著抑制HNSCC细胞中HPV E6介导的恶性表型。
本研究表明，E6癌基因通过调节多种信号通路导致HNSCC细胞的恶性转化。SLPI可以逆转E6癌基因对HNSCC的作用，这意味着SLPI对E6的功能抑制可能是一种有吸引力的治疗策略。
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