Du C W, Wen B G, Li D R, Lin Y C, Zheng Y W, Chen L, Chen J Y, Lin W, Wu M Y
Laboratory of Cancer Research, Cancer Hospital, Shantou University Medical College, Shantou 515031, P.R. China.
Exp Oncol. 2005 Dec;27(4):267-72.
Epstein - Barr virus (EBV)-encoded LMP1 is suggested to have an important role in the pathogenesis and development of nasopharyngeal carcinoma (NPC). Our previous study showed that As2O3 exhibited growth inhibition of NPC in animal model. Here, we further explore whether LMP1 is involved in As2O3 anticancer effects in NPC cell line.
Both the stable expressing LMP1 cell line HNE1-LMP1 and its parental cell line HNE1 without LMP1 expression were used as in vitro models to assess arsenic trioxide effect. Both cell lines were treated with As2O3 for 72 h. The median inhibition concentration (IC50) was assessed by the MTT assay. Apoptosis was observed by phase-contrast microscopy and TUNEL staining. The alteration of telomere lengths was detected by Southern blotting.
IC50 for As2O3 in HNE1-LMP1 cells and HNE1 cells was 2.22 and 5.09 micromol/L, respectively. After exposure to 2 and 4 micromol/L As2O3 for 72 h, the apoptotic index in HNE1-LMP1 was 26.27 -/+ 1.3 and 49.13 -/+ 1.4%, respectively. On the contrary, in HNE1 cells the apoptotic index was 12.6 -/+ 0.9 and 33.20 -/+ 1.3%, respectively. As compared with parental cell line HNE1, HNE1-LMP1 cells were more sensitive to growth inhibition and apoptosis (p < 0.001). The elongation of telomere length was also found in HNE1-LMP1 cells. Meanwhile, longer telomeres in HNE1-LMP1 cells failed to maintain telomere stabilization, instead, it prone to be shortened when exposure to As2O3, as comparing with HNE1 cells.
LMP1 plays important role in enhancing NPC cell response to As2O3. The elongation of telomere length induced by LMP1 may contribute to the mechanisms of As2O3 sensitivity.
有研究表明，爱泼斯坦-巴尔病毒（EBV）编码的潜伏膜蛋白1（LMP1）在鼻咽癌（NPC）的发病机制及发展过程中发挥重要作用。我们之前的研究显示，三氧化二砷（As2O3）在动物模型中对鼻咽癌具有生长抑制作用。在此，我们进一步探究LMP1是否参与As2O3对鼻咽癌细胞系的抗癌作用。
使用稳定表达LMP1的细胞系HNE1-LMP1及其不表达LMP1的亲本细胞系HNE1作为体外模型来评估三氧化二砷的作用。两种细胞系均用As2O3处理72小时。通过MTT法评估半数抑制浓度（IC50）。通过相差显微镜和TUNEL染色观察细胞凋亡情况。通过Southern印迹检测端粒长度的变化。
HNE1-LMP1细胞和HNE1细胞中As2O3的IC50分别为2.22和5.09微摩尔/升。在2微摩尔/升和4微摩尔/升As2O3处理72小时后，HNE1-LMP1细胞的凋亡指数分别为26.27±1.3%和49.13±1.4%。相反，在HNE1细胞中，凋亡指数分别为12.6±0.9%和33.20±1.3%。与亲本细胞系HNE1相比，HNE1-LMP1细胞对生长抑制和凋亡更敏感（p<0.001）。在HNE1-LMP1细胞中还发现了端粒长度的延长。同时，与HNE1细胞相比，HNE1-LMP1细胞中较长的端粒未能维持端粒稳定，相反，在暴露于As2O3时更容易缩短。
LMP1在增强鼻咽癌细胞对As2O3的反应中起重要作用。LMP1诱导的端粒长度延长可能是As2O3敏感性机制的一部分。
