亚致死照射促进肝癌细胞侵袭转移潜能增高的机制及其干预的初步研究

Radiotherapy(RT) represents one of major treatment methods for cancer. According to previous studies, sublethal irradiation can promote invasive and metastatic ability of descendant survival tumor cells. In clinical practice, we also observed that patients who received radiotherapy with local-controlled tumor but was not prolonged their survival time, and they were always suffered from metastatic tumor. Our privious study showed that the survival progeny of irradiated hepatic cancer cells show an increased invasive ability, and the invasivity is further increased when cells are cultured with conditioned medium from irradiated nonparenchymal cells (NPC). Consequently, we hypothesize that the conditioned medium changes the microenvironment of tumor cells, leading to an increased invasiveness and metastatic potential of tumor cell. Furhtermore, major objectives is to identify metastasis-promoting proteins closely associated with radiation induced NPCs secreation of differential cytokins in this protocol; then to evaluate their initial function. In this study, we also focus on whether COX-2 selective inhibitor celecoxib could down-regulate metastasis-related cytokines in conditioned irradiated medium of irradiated NPC, thus decrease survival progeny cancer cells's invasivity. We hope to devise a promising strategy in future tumor radiotherpy field.

放射治疗是目前肿瘤治疗的主要手段之一。现有研究表明，亚致死剂量照射可以提高存活肿瘤细胞的侵袭和转移能力。临床上，部分肿瘤经放射治疗后，局部控制良好，但并未延长生存期，多与肿瘤转移有关。课题组前期研究表明，大鼠肝癌细胞经辐射后存活的后代细胞，较原细胞侵袭转移能力增高, 且分离的大鼠肝脏非实质细胞辐射后的上清液可进一步提高其侵袭转移能力，推测辐射诱导了体外培养的大鼠肝脏非实质细胞表达多种细胞因子，与辐射共同作用于肿瘤细胞，致使其侵袭转移能力升高。本研究拟通过对非实质细胞辐射后上清液的细胞因子芯片及肿瘤细胞转移相关基因芯片检测，从全新的角度筛选辐射激活肿瘤转移能力的关键基因，再对其功能做进一步验证；并通过在大鼠非实质细胞培养液中加入塞来昔布，观察能否抑制与转移相关的细胞因子，从而降低残存肿瘤转移能力，以期为今后进一步提高放射治疗疗效提供新的依据和策略。

放射治疗是肝细胞癌(HCC)治疗的主要手段之一。HCC放疗失败的主要原因是肿瘤发生转移。本项目通过研究放疗后肿瘤细胞所处微环境的变化，照射后存活细胞的基因改变等来研究肿瘤转移的机理，并采用药物进行干预该进程。我们利用细胞因子芯片检测证明了辐射可刺激离体培养的大鼠肝脏非实质细胞（NPCs）可释放多种炎症及转移相关的细胞因子，如MMP-8、VEGF、IL-5、IL-2、Tie-2等。照射后的NPCs培养上清液（SR）较未照射上清液（SnonR）处理使大鼠肝癌照射后代细胞侵袭转移能力更强。药物塞来昔布（Celecoxib）可以抑制NPCs经辐射诱导产生的大量细胞因子，并且降低了残存肿瘤转移能力。进一步将SR及SnonR处理的大鼠肝癌照射后代细胞进行了表达谱芯片检测，所得差异表达基因进行功能富集分析和信号转导通路富集分析，发现这些表达差异显著的基因多数富集在肿瘤转移相关通路，如AMPK信号通路等。分别用AMPK激动剂和抑制剂处理后，肝癌细胞的侵袭转移能力出现了降低及增高，表明AMPK途径在这一过程中起着重要作用。蛋白印迹法证实，SR处理肝癌照射后代细胞组p-AMPK表达低于SnonR处理组，而p-mTOR则高于SnonR处理组。综上所述，辐射离体培养的大鼠NPCs的培养上清液可提高肝癌照射后代细胞的侵袭转移能力，其机理可能是照射后NPCs 通过分泌多种细胞因子，调控肝癌细胞的AMPK信号通路，从而促进肝癌转移，本研究为今后肝癌放射治疗控制肿瘤转移提供了新的思路。