Circumventing Acquired Resistance to Growth Factor Receptor Kinase Inhibitors

描述(由申请人提供)：使用酪氨酸激酶抑制剂(TKIs)的分子靶向癌症治疗的成功面临许多困难的挑战。其中最重要的是能够识别对靶向药物唯一敏感的不同癌症的亚组，通常通过存在暗示对靶向途径“依赖”或“上瘾”的遗传标记来识别。对于这些疗法的长期成功，同样重要的是理解和避免获得性耐药性，这是它们临床有效性的一个关键限制。针对生长因子受体的获得性耐药性不同于对基因毒性癌症化疗的耐药性，可能包括靶向受体的特定突变，以及信号网络中更复杂的功能变化。在这里，我们将使用非小细胞肺癌(NSCLC)细胞系模型，该模型似乎忠实地概括了具有表皮生长因子受体(EGFR)基因激活突变的癌症的关键信号依赖，确定了对EGFR TKIs极其敏感的肺癌亚群。我们概述了解决以前对这些药物敏感的肿瘤获得耐药性的三个目标：在目标1中，我们将建立对“第二代”不可逆EGFR抑制剂的获得性耐药性的细胞系模型，并使用遗传学、信号和功能分析来剖析潜在的机制。在目标2中，我们将使用高通量的酪氨酸激酶shRNA筛选来识别候选靶点，这些靶点的抑制可能绕过对EGFR抑制剂的耐药性。在目标3中，我们将使用慢病毒敲除/重建实验来量化耐药细胞对癌基因的依赖，包括启动EGFR突变和与获得性耐药相关的信号通路。总之，这些目标将为人类癌症对靶向生长因子受体的新型抑制剂获得耐药性的关键机制提供重要的见解。与公共卫生相关：了解对新的靶向癌症疗法敏感的癌症对这些疗法产生抗药性的机制，对于它们最终的临床成功至关重要。我们的方法旨在剖析这些抗癌药物耐药的分子基础。

DESCRIPTION (provided by applicant): The success of molecularly targeted cancer therapy using tyrosine kinase inhibitors (TKIs) faces a number of difficult challenges. Foremost among these is the ability to identify subsets of different cancers that are uniquely sensitive to targeted agents, often identified by the presence of genetic markers implying "dependence" or "addiction" to the targeted pathway. Equally important to the longterm success of these therapies is understanding and circumventing acquired drug resistance, which is a key limitation to their clinical effectiveness. Acquired resistance to drugs targeting growth factor receptors differs from resistance to genotoxic cancer chemotherapy, and may include both specific mutations in targeted receptors, as well as more complex functional alterations in signaling networks. Here we will use non-small cell lung cancer (NSCLC) cell line models that appear to faithfully recapitulate key signaling dependence of cancers with activating mutations in the Epidermal Growth Factor Receptor (EGFR) gene, identifying a subset of lung cancers with extreme sensitivity to EGFR TKIs. We outline three aims that address the acquisition of resistance in tumors that were previously sensitive to these agents: in Aim 1, we will generate cell line models for acquired resistance to "second generation" irreversible inhibitors of EGFR, and use genetic, signaling and functional analyses to dissect the underlying mechanisms. In Aim 2, we will use a high throughput shRNA screen of tyrosine kinases to identify candidate targets whose suppression may circumvent resistance to EGFR inhibitors. In Aim 3, we will use lentiviral knockdown/reconstitution experiments to quantitate oncogene dependence of drug resistant cells, both on the initiating EGFR mutation and on associated signaling pathways that contribute to acquired drug resistance. Together, these aims will provide important insight into critical mechanisms that underlie the acquisition of resistance to novel inhibitors targeting growth factor receptors in human cancer. PUBLIC HEALTH RELEVANCE: Understanding the mechanisms by which cancers that are sensitive to the new classes of targeted cancer therapies become resistant to these is critical to their eventual clinical success. Our approach is designed to dissect the molecular basis of resistance to these cancer drugs.