Mechanism of distant metastasis after radiotherapy for rectal cancer.

（目的）探讨直肠癌放疗后远处转移的机制。（方法）Balb/c裸鼠。切除直肠前壁，将HT-29细胞植入直肠后壁。7天后，采用RT-PCR和流式细胞仪分析比较放疗组和非放疗组的几种免疫指标。（结果）放疗组肿瘤组织中Foxp 3、Notch 1、Jagged 1 mRNA的表达比例与未治疗组相比无明显升高。放疗组脾脏Foxp 3表达率较对照组和未治疗组有升高趋势。结论直肠癌放疗中，血中Foxp 3表达上调引起的免疫耐受可能增加远处转移。Foxp 3可能是直肠癌放疗或放化疗后远处转移的重要调控因子。

(Aim)To clarify the mechanisim of distant metastasis after radiotherapy for rectal cancer.(Methods)We used Balb/c nude mice. We cut anterior wall of rectum, and implanted HT-29 cells into posterior wall. Seven days after, we compared the several immune factors between radiation therapy group and non-therapy group using RT-PCR and flow cytometric analysis.(Result)In radiotherapy group, Foxp3, Notch1, Jagged1 mRNA ratio in tumor were not significantly increased compared with non-therapy group. Foxp3 ratio in spleen tended to be higher in radiotherapy group, compared with control and non-therapy group.(Conculusion)In radiotherapy for rectal cancer, immune tolerance by Foxp3 up-regulation in blood may increase distant metastasis. Foxp3 may be a important factor to regulate distant metastasis in rectal cancer patients with radiotherapy or chemoradiotherapy.