The removal system at irradiated apoptotic cells

电离辐射是杀死癌细胞的强大代价。在放射治疗过程中，受照射的癌组织会缩小。然而，常规病理检查有时很难发现凋亡细胞，尤其是实体瘤。这一现象可能是由死亡癌细胞的快速假阳性细胞所解释的。吞噬细胞会识别死亡细胞的表面蛋白，即所谓的“吃我信号”。磷脂酰丝氨酸是这类分子的候选分子，但有很多这类分子与死亡细胞的吞噬作用有关。我们建立了QRSP-IR细胞系，该细胞系已接受10Gy射线照射。我们将这两个细胞系移植到C57B6小鼠的背部。移植的QRSP-IR在所有病例中都形成了显着的肿瘤块(5/5)，而注射亲本细胞的小鼠中只有40%出现了肿瘤块。QRSP-IR组肿瘤平均体积明显大于亲本细胞系。病理检查显示，照射后的细胞表现出较高的有丝分裂指数、局灶性侵袭倾向和宿主动物清除系统的存活特征。然后通过DNA芯片分析进行基因表达的综合检测。QRSP-IR组中592个基因表达水平较高，480个基因表达水平较低。有趣的是，这些基因包括CD14、清道夫受体或其他膜蛋白。我们将在未来从目前的候选基因中找到关键分子。

The ionizing irradiation is a powerful toll for killing the cancer cell. The irradiated cancer tissue will be shrinked during the radiological treatment. However, it is sometimes difficult to find the apoptotic cells with conventional pathological examination especially in the cases of solid tumors. This phenomenon may be explained by the rapid pahogocytosis of dead cancer cells. Phagocytic cell will recognize the surface proteins of dying cell, so called "eat me signal". Phosphatidyl serine is the candidate of such molecule, however there is a lot of such kind of molecules relating phagocytosis of dying cells. We established the cell line named QRSP-IR which already irradiated at the dose of 10Gy. We transplanted these two cell lines on the back of c57B6 mice. Transplanted QRSP-IR made a significant tumor mass in all cases (5/5) whereas only 40% of mice which injected parental cells exhibited the tumor mass. The mean volume of tumor mass with QRSP-IR was significantly lager than the mass with parent cell line. Pathological examination revealed that irradiated cell exhibited the higher mitotic index, focal invasion tendencies and the survival character from the removal system of host animal. Then we performed the comprehensive detection of gene expression by DNA chip analysis. The expression level of 592 genes was higher and 480 were lower in QRSP-IR mass. It was interesting that these genes included the CD14, scavenger receptor or other membranous proteins. We will find the key molecules from present candidate genes in the future.