Improving Radiation Therapy For Pancreatic Cancer

 描述（由申请方提供）：放射治疗在胰腺导管腺癌（PDAC）治疗中起着关键作用。然而，它面临着胰腺癌干细胞（PCSC）对电离辐射具有抵抗力的挑战。此外，最近的一项发现表明，辐射可以将非干细胞癌细胞重编程为癌症干细胞，这与我们的发现一致，即iPCSC。令人信服的证据表明，PDAC细胞在表达升高水平的醛脱氢酶1（ALDH 1），ALDHbrightcells，是PCSC/iPCSC。在过去，我们证明了特异性识别ALDH 1A 1同种型表位的细胞毒性T细胞（CTL）在体外和体内消除ALDHbright细胞。然而，基于过继性T细胞的免疫疗法的临床适用性受到HLA I类限制的限制，并且需要使用多种方法离体扩增自体或同种异体T细胞。为了克服CTL靶向ALDHbright细胞的局限性，我们测试了使用双硫仑（DSF）靶向PCSC的新方法。DSF是一种二硫代氨基甲酸盐和FDA批准的ALDH抑制剂，用于治疗酒精中毒。其对PDAC细胞的毒性已被证明通过结合必需微量元素铜（Cu++）以形成DSF/Cu络合物而增强。我们最近使用PDAC细胞系发现：i）体外分次照射后两天PCSC增加; ii）在治疗间隙期间DSF/Cu耗尽PCSC，并消除照射细胞的体外球体形成; iii）DSF/Cu下调照射的PDAC细胞中的关键癌症干细胞通路Wnt通路，以及iv）DSF/Cu阻断辐射诱导的干细胞基因的再表达mRNA。这些发现为我们的中心假设提供了理论基础，即DSF/Cu耗尽预先存在的PCSC和辐射诱导的PCSC，导致放射治疗的疗效显著增加。在目标1中，我们将确定DSF/Cu在体外和体内消除PCSC和iPCSC。在Aim 2中，我们将研究RT与DSF/Cu组合可以在新辅助治疗环境中使用小鼠中的异种和同基因胰腺肿瘤有效地消除干细胞和非干细胞PDAC细胞。在目标3中，我们将比较DSF/Cu、RT和5-氟尿嘧啶（5-FU）（PDAC的常用放射增敏剂）的组合与由RT和5-FU组成的常规放化疗在异种和同基因PDAC小鼠模型系统中的新辅助治疗环境中的疗效。在拟定研究结束时，我们将评价DSF/Cu作为既存PSCS/iPSCS的细胞毒性剂和iPCSC生成的阻滞剂，获得DSF/Cu增强放疗和放化疗疗效的机制的知识，并形成了一种新的新辅助治疗的基础，用于通过与FDA批准的药物DSF和营养补充剂葡萄糖酸铜。

 DESCRIPTION (provided by applicant): Radiation therapy plays a key role in pancreatic ductal adenocarcinoma (PDAC) treatment. However, it faces challenges from the fact that pancreatic cancer stem cells (PCSC) are resistant to ionizing radiation. Moreover, a recent finding indicates that radiation can reprogram nonstem- cancer cells into cancer stem cells, which is in agreement with our finding, namely iPCSC. Compelling evidence show that PDAC cells in expressing elevated levels of aldehyde dehydrogenase 1 (ALDH1), ALDHbrightcells, are PCSC/iPCSC. In the past, we demonstrated that cytotoxic T cells (CTL) specifically recognizing an epitope from the ALDH1A1 isoform eliminate ALDHbright cells in vitro and in vivo. However, the clinical applicability of adoptive T cell-based immunotherapy is limited by HLA class I restriction and requires ex vivo expansion of autologous or allogeneic T cells using a variety of methodologies. To overcome the limitations of CTL-targeting of ALDHbright cells, we tested the novel approach of using disulfiram (DSF) to target PCSC. DSF is a dithiocarbamate and an FDA-approve inhibitor of ALDH for treatment of alcoholism. Its toxicity to PDAC cells has been shown to be enhanced by the binding of the essential trace element copper (Cu++) to form DSF/Cu complexes. We found recently using PDAC cell lines that: i) PCSC increased two days after in vitro fractionated irradiation; ii) DSF/Cu depleted PCSC during the treatment gap, and abolished in vitro sphere formation of irradiated cells; iii) DSF/Cu downregulated Wnt pathway, a key cancer stem cell pathway, in irradiated PDAC cells, and iv) DSF/Cu blocked radiation induced re-expressing mRNA of stemness genes. These findings provide the rationale for our central hypothesis that DSF/Cu depletes pre-existing PCSC and radiation-induced PCSC which results in significant increases in the efficacy of radiation therapy. In Aim1, we will determine that DSF/Cu eliminates both PCSC and iPCSC in vitro and in vivo. In Aim2, we will examine that RT combined with DSF/Cu can effectively eliminate stem- and nonstem- PDAC cells in a neoadjuvant setting using xeno- and syngeneic- pancreatic tumors in mice. In Aim3, we will compare the efficacy of combination of DSF/Cu, RT and 5-Fluorouracil (5-FU), a commonly used radiosensitizer for PDAC vs conventional chemoradiation consisting of RT and 5-FU in a neoadjuvant setting in xeno- and syngeneic- PDAC mouse model systems . At the conclusion of the proposed studies, we will have evaluated DSF/Cu as a cytotoxic agent of pre-existing PSCS/iPSCS and as a blocker of generation of iPCSC, obtained knowledge of the mechanism(s) by which DSF/Cu enhances efficacy of radiation and chemoradiation therapy, and formed the foundation of a novel neoadjuvant therapy for improved efficacy of radiation and chemoradiation by combination with a FDA approved drug DSF and a nutrition supplement Copper gluconate.