DEVELOPMENT OF THE EARLY INDICATOR FOR LATE RADIATION DAMAGE

我们以前曾描述过放射后肾近曲小管细胞增殖增加和出现异常大的细胞核。已经提出了一种模型，即大的核细胞可能正在死亡，并且增加的增殖可能导致这些细胞的有丝分裂死亡并引起功能损伤。用RT-PCR方法检测照射后肾组织中c-fos和c-myc的表达，发现照射后早期（24小时）c-fos和c-myc的表达增加，可能与DNA合成增加有关。在9 ~ 15戈伊的照射剂量范围内，c-myc高表达的发生率随照射剂量的增加而增加。12戈伊照射后24 h检测c-fos和c-myc表达，并于照射后9个月随访BUN值。c-fos和c-myc阳性小鼠的BUN大多数升高，而c-fos和c-myc阴性小鼠的BUN均无变化。检测c-fos和c-myc的表达可能是肾放射损伤的早期指标。

We have previously described the increased proliferation and appearance of abnormally large nuclei in renal proximal tubule cells after radiation. A model has been proposed that the large nuclear cells might be dying and the increased proliferation might lead to mitotic death of these cells and cause functional damage. We measured the expression of c-fos and c-myc taking the ratio of densities of bands for irradiated portion to unirradiated portion of the kidney after RT-PCR procedure, and found the c-fos and c-myc expression increased very early (24 hours) after irradiation, probably representing increased DNA synthesis. The incidence of high c-myc expression increased according to radiation dose from 9 to 15 Gy. Then we measured the c-fos and c-myc expression 24 hours after 12 Gy irradiation, and followed BUN values representing the renal function of irradiated and right nephrectomized mice for 9 months after irradiation. Most of c-fos and c-myc positive mice showed increased BUN level, while all mice with negative c-fos and c-myc showed no BUN change. Measuring c-fos and c-myc expression seems to be a potential very early indicator of late radiation damage of kidney.