Department of Otolaryngology/Head and Neck Surgery, Louisiana State University Health Sciences Center, Shreveport, LA, United States.
Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA, United States.
Oral Oncol. 2021 Nov;122:105578. doi: 10.1016/j.oraloncology.2021.105578. Epub 2021 Oct 22.
Tobacco exposure and human papillomavirus (HPV) infection are among the main risk factors for the development of head and neck squamous cell carcinoma (HNSCC). Interestingly, recent studies show that tumors from HPV positive (HPV+) smokers and non-smokers have similar mutational profiles, which suggests that HPV could prevent mutation induction or accumulation in the intermediate risk group composed of HPV+ smokers. Hence, we tested this observation by analyzing the effects of 4-Nitroquinoline N-oxide (4NQO), a mutagen and smoking mimetic, in NOK (normal oral keratinocytes), NOK (NOK cells transfected with E6.E7 oncogenes of HPV), HPV+ and HPV negative (HPV-) HNSCC cells. Oxidative DNA damage, γH2AX foci formation, DNA repair protein activation, cell cycle phase analysis, apoptotic cell death, cell viability and clonogenic cell survival were analyzed after 4NQO treatment in NOK, NOK, HPV+ and HPV- HNSCC cells. 4NQO increased oxidative base damage and γH2AX foci formation in NOK, HPV+ and HPV- HNSCC cells. Phosphorylation of homologous recombination (HR) repair proteins was higher in NOK and HPV+ HNSCC cells compared to NOK and HPV- HNSCC cells respectively. HPV+ and HPV- HNSCC cells showed differential activation of cell cycle regulatory proteins, increased apoptosis, and decreased cell viability upon 4NQO-induced DNA damage. Taken together, 4NQO (a smoking mimetic), induced higher activation of HR repair in HPV+ HNSCC cells compared to HPV- HNSCC cells. This may allow for increased mutational resistance and help explain why HPV+ smokers have a worse prognosis than HPV+ non-smokers.
烟草暴露和人乳头瘤病毒（HPV）感染是头颈部鳞状细胞癌（HNSCC）发展的主要危险因素之一。有趣的是，最近的研究表明，HPV 阳性（HPV+）吸烟者和非吸烟者的肿瘤具有相似的突变特征，这表明 HPV 可能会防止 HPV+吸烟者的中间风险组中的突变诱导或积累。因此，我们通过分析 4-硝基喹啉 N-氧化物（4NQO），一种诱变剂和吸烟模拟物，在 NOK（正常口腔角质形成细胞）、NOK（转染 HPV E6.E7 致癌基因的 NOK 细胞）、HPV+和 HPV- HNSCC 细胞中的作用来检验这一观察结果。在 NOK、NOK、HPV+和 HPV- HNSCC 细胞中用 4NQO 处理后，分析了氧化 DNA 损伤、γH2AX 焦点形成、DNA 修复蛋白激活、细胞周期分析、细胞凋亡、细胞活力和克隆细胞存活。4NQO 增加了 NOK、HPV+和 HPV- HNSCC 细胞中的氧化碱基损伤和γH2AX 焦点形成。与 NOK 和 HPV- HNSCC 细胞相比，NOK 和 HPV+ HNSCC 细胞中同源重组（HR）修复蛋白的磷酸化水平更高。HPV+和 HPV- HNSCC 细胞在 4NQO 诱导的 DNA 损伤后显示出细胞周期调节蛋白的差异激活、增加的凋亡和降低的细胞活力。总之，4NQO（一种吸烟模拟物）在 HPV+ HNSCC 细胞中诱导的 HR 修复激活高于 HPV- HNSCC 细胞。这可能允许更高的突变抗性，并有助于解释为什么 HPV+吸烟者的预后比 HPV+非吸烟者差。
