高强度聚焦超声抑制小鼠黑色素瘤细胞B16-F10在体内的转移

High-intensity focused ultrasound inhibits tumor metastasis in a melanoma-bearing mouse model

目的在黑色素瘤的小鼠模型上,探讨高强度聚焦超声（HIFU）处理对黑色素瘤细胞体内转移的影响。方法皮下注射小鼠黑色素瘤细胞B16-F10以构建小鼠黑色素瘤皮下移植瘤模型;待肿瘤最长径长至7~10 mm时进行HIFU处理,并设置实验对照组（荷瘤鼠辐照HIFU但保持治疗头功率源开关关闭,即假照组）;治疗后每3 d测量肿瘤长径和短径,共观察3周,绘制肿瘤曲线,统计生存率和转移率,并通过实时荧光定量PCR测定血液中黑色素瘤细胞3个标志物的相对表达量以监测血液中循环黑色素瘤细胞的数量,它们分别是黑色素瘤相关抗原A3（MAGE-A3）、T细胞1识别的黑色素瘤抗原（MART1）以及同源转化成对框基因转录因子PAX3）;在HIFU治疗后14 d,通过尾静脉注射再次移植B16-F10细胞,观测其肺转移率。结果（1）各自的中位生存时间及95%可信区间（CI）：假照组分别为19.00 d和17.14~20.86 d,HIFU组则分别为26.00d和24.76~27.25 d,生存率差异显著（P〈0.01）;从治疗后第20天起,两组小鼠的肿瘤体积差异明显,从HIFU处理后第20天开始,包括处理后第23、26天,辐照组小鼠肿瘤体积明显小于假照组（P〈0.05）;（2）实时荧光定量PCR结果显示HIFU组小鼠在治疗后第7天的MAGE-A3、MART1和PAX3三个指标都明显低于假照组（P〈0.05）,在治疗后第14天其MAGE-A3的表达量仍然明显低于假照组（P〈0.05）;（3）在HIFU治疗后14 d通过尾静脉再次移植相同肿瘤细胞,HIFU组肺转移灶的数量明显低于假照组（P〈0.05）,肿瘤转移抑制率为42.4%。结论 HIFU处理能够抑制黑色素瘤细胞在体内转移的发生,其机制可能涉及减少肿瘤细胞从原发灶的脱落和瘤细胞在肺部的定植能力。

Objective To investigate the effect of high-intensity focused ultrasound（HIFU） on tumor metastasis in mouse model bearing melanoma xenograft. Methods Mice bearing murine melanoma B16- F10 cell xenograft were randomized for shamHIFU or HIFU exposure when the tumors grew to a maximum diameter of 7-10 mm, and the tumor size was measured every 3days. The cumulative survival rate of the mice and tumor metastasis rate were calculated, and the circulating melanoma cells were detected using q RT- PCR. At 14 days after HIFU treatment, B16- F10 cells were retransplanted via the tail vein and the pulmonary metastatic nodules were counted. Results The median survival time of the mice was 19.00 days（95 % CI 17.14-20.86 days） in the sham group and 26.00 days（95% CI 24.76- 27.25 days） in HIFU group. The cumulative survival rate in the HIFU group was significantly higher than that in sham-HIFU group（P〈0.01）, and the tumor size was significantly smaller in HIFU group at 20, 23, and 26 days after HIFU treatment（P〈0.05）. Compared with the sham- HIFU group, HIFU group had significantly lower levels of MAGE-A3, MART1 and PAX3 at 7 days after HIFU（P〈0.05） with still lower MAGE-A3 level at 14days（P〈0.05）. HIFU group showed a significantly smaller number of pulmonary metastatic nodules following tumor cell retransplantation than in sham- HIFU group（P〈0.01） with a metastasis inhibition rate of 42.4%. Conclusion HIFU treatment can inhibit tumor metastasis in melanoma-bearing mice possibly by reducing tumor cell detachment from the primary tumor site and suppressing colonization of the circulating melanoma cells.