Study of gene therapy for lymph node metastasis of oral squamous cell carcinoma

大约30%的口腔癌患者有颈部淋巴结转移。浅表淋巴结多发转移和淋巴结病变再生长的治疗非常困难。利用具有复制能力的1型单纯疱疹病毒（HSV-1）进行溶瘤病毒治疗是治疗此类淋巴结病变的一种很有前途的方法，因为据报道HSV-1株HF10对乳腺癌的淋巴结转移有效。我们将口腔鳞状细胞癌（SCC）转移淋巴结源性细胞皮下接种于裸鼠颊区，建立了颈部淋巴结转移和肺转移的模型系统。作为口服SCC溶瘤病毒治疗药物，研究了γ_134.5缺失突变体R849和HF10原株HF对口腔SCC细胞的抗肿瘤活性。R849和HF均能复制，细胞活力呈时间依赖性下降。在r849感染的细胞中观察到细胞圆缩，而HF则诱导多核巨细胞。但R849的病毒产量高于HF。当R849感染R849并在白血病分化剂六亚甲基双卡他胺（HMBA）存在下培养时，病毒产量明显增加。采用口服SCC裸鼠模型，分别将R849单独或联合腹腔注射HMBA，观察R849的抗肿瘤作用。R849治疗可抑制肿瘤生长，HMBA治疗效果进一步增强。1型单纯疱疹病毒感染的炎症反应在感染部位产生氧自由基。我们证明过氧化氢能增强感染细胞中HSV-1的释放。

Approximate 30 % of oral cancer patients have cervical lymph node metastasis. It is very hard to treat multiple metasatsis of superficial lymph nodes and regrowth of lymph node lesions. Oncolytic virotherapy with a replication-competent herpes simplex virus type 1 (HSV-1) is a promising approach for the treatment of such lymph node lesions, because HSV-1 strain HF10 was reported to be effective for lymph node metastasis of mammary cancer. We inoculated oral squamous cell carcinoma (SCC) cells derived from a metastatic lymph node subcutaneously into buccal area of nude mice and made a model system of cervical lymph node metastasis and lung metastasis. As agents for oncolytic virotherapy for oral SCC, γ_134.5-deficent mutant R849 and HF, the original strain of HF10, were tested for anti-tumor activity in oral SCC cells. Both R849 and HF could replicate and cell viability was decreased in a time-dependent manner. Cell rounding was observed in R849-infected cells, whereas HF induced multinuclear giant cells. However, the virus yield of R849 was higher than that of HF. When R849 was infected with R849 and cultured in the presence of hexamethylene bisacatamide (HMBA), a differentiating agent of leukemia, the virus production was increased markedly. The anti-tumor effect of R849 was also examined with the use of nude mouse model of oral SCC by injecting R849 into the tumors alone or in combination with intraperitoneal injection of HMBA. The tumor growth was suppressed by R849 treatment and the effect was further enhanced with HMBA. Inflammation response to HSV-1 infection produces oxygen radicals at the infection site. We demonstrated that hydrogen peroxide enhanced the release of HSV-1 from infected cells.