Role of CD44 in adaptive plasticity of pancreatic cancer

CD44在胰腺癌适应性可塑性中的作用

• 批准号: 8925205
• 负责人: James W. Freeman
• 金额: --
• 依托单位: SOUTH TEXAS VETERANS HEALTH CARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8925205
• 关键词: Address; Adenocarcinoma Cell; Adverse effects; Antibodies; Biological Markers; Biology; CD44 Antigens; CD44 gene; Cancer Cell Growth; Cell Line; Cells; Data; Down-Regulation; Engraftment; Environment; Epithelial; Excision; Exons; Flow Cytometry; Gene Expression; Genetic Transcription; Growth; Homing; Hyaluronan; Hypoxia; Immigration; Immunoglobulin Class Switching; Integral Membrane Protein; Kinetics; Knowledge; Laboratories; Lead; Link; Malignant Neoplasms; Malignant neoplasm of pancreas; Mediating; Metastatic Lesion; Micrometastasis; Modeling; Molecular; Neoplasm Metastasis; Pancreatic Ductal Adenocarcinoma; Patients; Phenotype; Play; Population; Process; Property; Protein Isoforms; Proteins; Proteoglycan; RNA Splicing; Reporting; Research; Resistance; Resistance development; Role; Signal Transduction; Site; Snails; Stem cells; Stress; Stromal Cells; Switch Genes; Testing; Transcription Repressor/Corepressor; Treatment Efficacy; Variant; base; cancer cell; cancer stem cell; chemotherapy; epithelial to mesenchymal transition; gemcitabine; improved; in vivo; insight; malignant breast neoplasm; mouse model; neoplastic cell; outcome forecast; pancreatic cancer cells; phrases; prevent; public health relevance; response; small hairpin RNA; therapy resistant; tumor; tumor progression

 DESCRIPTION (provided by applicant): Adaptive plasticity is a phrase used to explain how cancer cells gain selective growth and survival capabilities through phenotypic changes in response to their environment. Adaptive plasticity is exemplified by epithelial to mesenchymal transition (EMT) a process, which enables cancer cells to become migratory and invasive as well as having an increase in survival properties. This process can be reversed to a mesenchymal to epithelial transition (MET), which is believed to favor tumor engraftment and growth of cancer cells at metastatic sites. EMT in cancer cells is linked with isoform switching of the transmembrane protein CD44 from expressing the CD44 variant isoform (CD44v) to expressing CD44 standard form (CD44s). In this context we found that treatment of BxPC3 pancreatic ductal adenocarcinoma (PDAC) cell line with gemcitabine induces EMT and a high level of expression of CD44s with a decrease in expression of CD44v isoforms. This suggests that an adverse effect of chemotherapy may drive EMT, enhancing invasiveness and rendering tumor cells more resistant to chemotherapy. Moreover, we were able to use flow cytometry to select out from a PDAC cell lines (CFPAC-1 and AsPC1) a subpopulation of cells expressing high levels of CD44s. Knockdown of CD44s, in these cells, caused them to undergo MET, to be less invasive and to become more responsive to chemotherapy. These studies suggest that chemotherapy or other environmental stresses may induce a CD44s phenotype that promotes survival and is more invasive; however optimal tumor regrowth following chemotherapy or growth after engraftment of micrometastases may require re-switching to a CD44v phenotype and down regulation of CD44s expression. We hypothesize that CD44s and its variant isoforms are key regulators of adaptive plasticity in pancreatic cancer cells. We further hypothesize that understanding the molecular basis for adaptive plasticity will provide new strategies for improving therapy. These studies represent new data from our laboratory and build on 20 years of research solely focused on the biology and treatment of pancreatic cancer. To address these hypotheses we propose the following three objectives. Objective 1. Determine the functional relevance of CD44s and CD44v in PDAC. This objective will be addressed using isogenic matched cell line models in which expression of CD44s and CD44v isoforms are regulated. The effects on modulating expression of CD44v and CD44s will be assessed for phenotype, invasiveness, response to chemotherapy, tumor engraftment and growth. Objective 2. Determine the mechanism(s) that regulates CD44 isoform switching and CD44 expression. This objective will determine the potential role of EMT related transcriptional repressors Snail and Zeb1 in suppressing ESRP1 that is required for expression of CD44v isoforms and further identify the mechanisms that lead to the increased transcription of CD44s. Objective 3. Determine whether anti-CD44 antibody prevents CD44 isotype switching or expression level and whether this improves response to chemotherapy and reduces metastasis. These studies will provide important new insights related to adaptive plasticity and determine whether this knowledge can be used to counter act adverse effects of chemotherapy induced phenotypic switching. Inhibiting or reversing the switch towards an EMT phenotype may prove to be an important strategy for increasing the response to chemotherapy and patient survival.

 描述（由申请人提供）： 自适应可塑性是一个短语，用于解释癌细胞如何通过对环境的反应表型变化来获得选择性的生长和存活能力。自适应可塑性是通过上皮到间充质转变（EMT）的过程来体现的，该过程使癌细胞能够迁移和侵入性，并具有增加的生存特性。这个过程可以逆转为间质转变（MET），据信这过程有利于肿瘤的肿瘤植入和癌细胞在转移性部位的生长。癌细胞中的EMT与从表达CD44变体同工型（CD44V）到表达CD44标准形式（CD44S）的跨膜蛋白CD44的同工型转换有关。在这种情况下，我们发现用吉西他滨诱导EMT的BXPC3胰腺导管腺癌（PDAC）细胞系的处理，CD44V同工型的表达降低，CD44S的高表达水平。这表明化学疗法的不良影响可能会促进EMT，增强侵袭性并使肿瘤细胞对化学疗法具有更耐药性。此外，我们能够使用流式细胞仪从PDAC细胞系（CFPAC-1和ASPC1）中选择表达高水平CD44S的细胞的亚群。在这些细胞中，CD44的敲低导致它们经历了MET，其侵入性较小，并且对化学疗法的反应更快。这些研究表明，化学疗法或其他环境应力可能会诱导CD44S表型，从而促进生存，并且更具侵入性。但是，在植入微晶后化学疗法或生长后，最佳的肿瘤调节可能需要将CD44V表型重新开关并调节CD44S表达。我们假设CD44及其变异同工型是胰腺癌细胞自适应可塑性的关键调节剂。我们进一步假设，了解自适应可塑性的分子基础将为改善治疗提供新的策略。这些研究代表了我们实验室的新数据，并建立在20年的研究中，仅关注胰腺癌的生物学和治疗。为了解决这些假设，我们提出以下三个目标。目标1。确定PDAC中CD44S和CD44V的功能相关性。该目标将使用等源性匹配的细胞系模型来解决，其中调节CD44S和CD44V同工型的表达。将评估对CD44V和CD44的调节表达的影响，以评估表型，侵入性，对化疗，肿瘤植入和生长的反应。目标2。确定调节CD44同工型切换和CD44表达的机制。该目标将确定EMT相关转录表示的潜在作用蜗牛和Zeb1在抑制CD44V同工型表达所必需的ESRP1中的潜在作用，并进一步确定导致CD44s转录增加的机制。目标3。确定抗CD44抗体是否阻止CD44同种型切换或表达水平，以及这是否可以改善对化学疗法的反应并减少转移。这些研究将提供与自适应可塑性相关的重要新见解，并确定是否可以使用这些知识来抵抗化学疗法诱导的表型转换的不利影响。抑制或逆转向EMT表型的转换可能被证明是增加对化学疗法和患者生存的反应的重要策略。