Nucleoside Transporter-Connexin Interplay in Pancreatic Cancer Chemotherapy

描述（由申请人提供）：对核苷类似物药物（如吉西他滨）的化疗耐药是胰腺癌预后极差的主要潜在原因之一。虽然细胞核苷转运蛋白（nt）和细胞间隙连接蛋白（Cxs）在决定肿瘤核苷药物暴露中的关键作用已经开始出现，但它们在决定核苷类似物化学敏感性方面的功能相互作用以及它们在预测化疗反应方面的潜力仍然未知。我们的长期目标是改善胰腺癌的化疗管理。本R15应用的总体目的是研究NT-Cx在胰腺癌化疗中的相互作用。中心假设是NT-Cx组合表达的类型将决定化疗敏感性，并且可以靶向特定组合以增加抗肿瘤功效。这一假设是基于对NT和Cx的连续研究以及最近发现的胰腺肿瘤中NT和Cx亚型的非遗传功能改变而提出的。这项研究的基本原理是，了解核苷类似物敏感性的精确决定因素将有助于预先选择适合这种治疗的患者，并确定临床策略，以提高对不良反应者的疗效。特异性目的1将定义NT-Cx组合在核苷类似物化学敏感性中的作用。工作假设是，吉西他滨在表达高浓度NT1 (hCNT1)-Cx32组合的细胞中具有更强的细胞毒性，并且由于其中一种成分的丢失而产生的化学耐药可以被另一种成分有效地补偿。这一假设是基于NTs和xs在胰腺肿瘤中的表达和渗透特性。具体目标2将确定调节NT-Cx相互作用以提高化学敏感性的调节因子。工作假设是，NT-Cx组合的有利操纵，以增加药物暴露可以通过操纵钙粘蛋白或microrna来实现。这一假设是基于申请人的研究，该研究显示钙粘蛋白控制Cx组装和microrna作为hCNT1的推定调节因子。具体目标3将研究使用NT-Cx组合的核苷类似物反应的体内可预测性。工作假设是，由特异性NT和Cxs组成的复合指数比现有的单一指数（即仅平衡NT1 (hENT1)）更好地预测吉西他滨在体内的反应。这一假设是基于在体外培养的胰腺癌细胞中获得的初步结果的推断。这项工作的预期结果是描述NT-Cx在核苷类似物化疗敏感性中的相互作用，改善NT-Cx介导的药物靶向的策略，以及评估预测胰腺癌亚型化疗反应的临床措施。这种方法是创新的，因为它侧重于判断化疗反应的综合指标。这一贡献是重要的，因为它将使后续的转化研究有望改善胰腺癌患者的治疗和生存结果。

DESCRIPTION (provided by applicant): Chemoresistance to nucleoside analog drugs (e.g., gemcitabine) is one of the main underlying reasons for the extremely poor prognostic state of pancreatic cancer. While the pivotal roles of cellular nucleoside transporters (NTs) and intercellular gap junctional connexins (Cxs) in determining tumor exposure of nucleoside drugs have begun to emerge, their functional interplay in determining nucleoside analog chemosensitivity and their potential in predicting response to chemotherapy remain unknown. Our long-term goal is to improve the chemotherapeutic management of pancreatic cancer. The overall objective of this R15 application is to investigate NT-Cx interplay in pancreatic cancer chemotherapy. The central hypothesis is that the type of NT-Cx combination expressed will dictate chemosensitivity and that the specific combination(s) can then be targeted to increase anti-tumor efficacy. This hypothesis has been formulated on the basis of the continuum of studies on NTs and Cxs and the recent discovery of non-genetic functional alterations in NT and Cx subtypes in pancreatic tumors. The rationale underlying the proposed research is that understanding the precise determinants of nucleoside analog sensitivity will help in the preselection of patients suitable for this type of therapy and the identification of clinical strategies to increase efficacy in poor responders. Specific aim 1 will define the role of NT-Cx combinations in nucleoside analog chemosensitivity. The working hypothesis is that gemcitabine cytotoxicity will be superior in cells expressing the concentrative NT 1 (hCNT1)-Cx32 combination, and that chemoresistance due to the loss of one component can be effectively compensated by the other. This hypothesis is based on the expression and permeation characteristics of NTs and Cxs in pancreatic tumors. Specific aim 2 will determine the regulators governing NT-Cx interplay to improve chemosensitivity. The working hypothesis is that the favorable manipulation of NT-Cx combinations to increase drug exposure can be achieved by manipulating cadherins or microRNAs. This hypothesis is based on the applicant's studies showing cadherin control of Cx assembly and microRNAs as putative regulators of hCNT1. Specific aim 3 will investigate the in vivo predictability of nucleoside analog response using NT-Cx combinations. The working hypothesis is that a composite index comprising of specific NTs and Cxs will better predict in vivo gemcitabine response than with the existing single index (i.e., equilibrative NT 1 (hENT1) alone). This hypothesis is based on the extrapolation of preliminary in vitro results obtained in cultured pancreatic cancer cells. The anticipated outcomes of this work are the delineation of NT-Cx interplay in nucleoside analog chemosensitivity, strategies to improve NT-Cx-mediated drug targeting, and evaluation of clinical measures for predicting chemotherapeutic responses in pancreatic cancer subtypes. This approach is innovative because it focuses on a comprehensive index for judging chemotherapeutic response. This contribution is significant because it will enable subsequent translational studies that are expected to improve treatment and survival outcomes in pancreatic cancer patients.