基于EPR监测乳腺癌肿瘤微环境氧分压水平作为化疗敏感的指标研究

Scheduling of chemotherapy based on direct monitoring of pO_2 in tumor microenvironment by EPR oximetry

背景与目的:肿瘤微环境在介导肿瘤获得性耐药的外源性因素中发挥了重要作用。许多化疗药物的抗肿瘤效应依赖于肿瘤微环境氧分压(oxygen pressure,pO_2)水平状况。该研究拟探讨基于电子顺磁共振(electron paramagnetic resonance,EPR)技术监测肿瘤富氧环境下增加化疗敏感性的可行性。方法:采用MCF-7细胞建立人乳腺癌裸鼠移植瘤,通过EPR监测化疗时肿瘤组织pO_2的水平。比较基于pO_2峰值化疗与常规化疗不同模式下肿瘤体积的变化,通过流式细胞技术检测肿瘤细胞凋亡。采用激光多普勒组织灌注检测仪检测肿瘤局部血流量(regional blood flow,RBF),分光光度计检测肿瘤线粒体还原型烟酰胺腺嘌呤二核苷酸脱氢酶(NADH-DH)、琥珀酸细胞色素C还原酶(SCR)和细胞色素C氧化酶(Cc O)活性。结果:基于pO_2峰值化疗及常规化疗后较对照组肿瘤体积均显著缩小[(1 220.75±148.91)mm^3、(1 788.42±172.30)mm^3和(2 512.55±201.22)mm^3,P<0.01],但基于pO_2峰值化疗组抑瘤率显著高于常规化疗组(51.43%vs 28.82%,P<0.01);移植瘤细胞凋亡率检测进一步证实,基于pO_2峰值化疗较常规化疗更利于杀伤肿瘤细胞(P<0.001)。该研究初步研究了肿瘤微环境pO_2变化的机制:这与化疗后肿瘤组织线粒体耗氧与组织局部血流量之间的平衡改变有关。结论:基于EPR氧测定技术实现对肿瘤组织pO_2的长期监测,并以pO_2峰水平作为化疗时间窗提高化疗敏感性,为临床个体化化疗提供新的策略和思路。

Background and purpose： Tumor mieroenvironment plays an important role in the introduction of foreign factors that mediate tumor acquired resistance. The antitumor effects of many chemotherapeutic agents depend on the level of oxygen pressure （PO2） in tumor microenvironmenL This study aimed to evaluate electron paramagnetic reso- nance （EPR）-based monitoring on an oxygen-enriched tumor mieroenvironment to increase chemotherapeutic sensitivity. Methods： MCF-7 cells were used to establish human breast cancer in nude mice. EPR was used to directly measure pO2 level in vivo. Tumor tissues were collected, and mitochondrial activity was assayed on the basis of the kinetics of enzyme-catalyzed reactions. A laser Doppler monitor was used to detect regional blood flow. Tumor apoptotic rate was analyzed by flow cytometry. Results： The tumor volume decreased more evidently in the chemotherapy group with oxy- gen-enriched environment than that in the conventional chemotherapy group after the treatment was administered （P〈0.01）, After chemotherapy was completed, the apoptotic rate of tumor cells was significantly higher in the chemotherapy group with oxygen-enriched environment than that in the conventional chemotherapy group （P〈0.001）. This study examined the mechanism ofpO2 changes in tumor microenvironment： This was related to the change of the balance between the oxygen consumption and the regional blood flow in the tumor tissues after chemotherapy. Conclusion： Based on the characteristics ofpO2 changes in the tumor microenvironment after chemotherapy was completed, the selection of chemotherapy mode for the treatment in 1902 peak time window improves the sensitivity of chemotherapy, which provides a new idea for individual- ized chemotherapy in clinical applications.