The role of exosome-mediated crosstalk between cancer cells and nerves in pancreatic cancer

胰腺癌是公认的最致命的癌症之一。虽然转移到次级器官在PDAC中很常见，但它也表现出癌细胞高频率地渗透到神经，采用另一种转移方式。这种特殊的转移途径被称为神经侵袭(NI)。它已经成为PDAC的标志之一，因为它经常与悲观的预后相关。在目前的方案中，我们的目标是调查外显子介导的胰腺癌细胞和神经周围微环境之间的串扰是否对肿瘤进展有影响。通过释放外切体，癌细胞可以将致癌分子穿梭到受体细胞和细胞外基质中，改变局部和全身的肿瘤微环境以支持癌症。然而，外显体介导的癌细胞和神经之间的串扰以及对胰腺癌NI的影响仍然难以捉摸。因此，这项建议的原则将是研究肿瘤来源的外切体如何重新编程神经微环境来诱导NI。在Aim1.1中，我们将验证这样一种假设，即神经侵袭性胰腺细胞和/或激活的成纤维细胞(胰腺星状细胞)中的雪旺细胞和神经细胞外切体预处理会在体外和体内增加胰腺癌细胞的神经侵袭力。为了进一步了解PDAC衍生的外体如何支持神经侵袭，我们将在体内通过靶向不同的途径来干扰外体串扰。这也将有助于阐明外切体功能受损是否可能成为癌症治疗的潜在靶点。在Aim1.2中，我们想要评估来自高和低NI-势的PDAC细胞的外切体是否可以决定神经趋向性。我们的目标是识别能够增加NI的外体相关分子。随后，我们将研究靶向这些特定的外体标记是否可以减少神经侵袭。在目标2中，我们将研究雪旺细胞来源的外切体对癌细胞神经侵袭性的相互影响。这是一个新的概念，因为到目前为止，大多数研究都只集中在肿瘤细胞的单向外体转移对(神经)微环境的作用。这些数据可以为研究外切体介导的侵袭行为提供一个新的视角，并将进一步评估肿瘤微环境在胰腺癌肿瘤进展中的作用。此外，我们计划在雪旺细胞来源的外体中确定促进NI的靶点，这些靶点可以靶向抑制受体PDAC细胞的激活和促肿瘤作用。AIM 1和AIM 2的结果将有助于识别潜在的诊断和预测标记物，我们计划在AIM 3的大量胰腺癌患者队列中进行验证。这些数据将提供一种新的方法，将患者分成不同的风险类别，并提高诊断水平，以早期发现复发的PDAC。

Pancreatic cancer (PDAC) is widely recognized as one of the most deadly cancer. While metastasis to secondary organs is common in PDAC, it also exhibits a high frequency of cancer cell penetration into nerves, employing another mode of metastasis. This special route of metastasis has been known as neural invasion (NI). It has become one of the hallmarks of PDAC because it is frequently associated with a dismal prognosis. In the current proposal, we aim to investigate if the exosome-mediated crosstalk between pancreatic cancer cells and the perineural microenvironment have an effect on tumor progression. By the release of exosomes, cancer cells can shuttle oncogenic molecules to recipient cells and the extracellular matrix, altering the local and systemic tumor microenvironment in support of cancer. However, the exosome-mediated crosstalk between cancer cells and nerves and the impact on the NI in pancreatic cancer remains elusive. Thus, the principle of this proposal will be to investigate how tumor-derived exosomes reprogram the nerve microenvironment to induce NI. In Aim1.1, we will test the hypothesis that pre-conditioning of Schwann cells and neurons with exosomes from neural invasive pancreatic cells and/or activated fibroblasts (pancreatic stellate cells) will increase the neuro-invasiveness of pancreatic cancer cells in vitro and in vivo. To further understand how PDAC-derived exosomes support the neural invasion, we will disrupt the exosomal crosstalk by targeting different pathways in vivo. This will help also to elucidate if the impairment of the exosome function might be a potential target in cancer therapy. In Aim1.2, we want to evaluate if exosomes from PDAC cells with high and low NI-potential can determine neurotropism. We aim to identify exosome-associated molecules that can increase NI. Subsequently, we will investigate if targeting those specific exosomal markers can reduce neural invasion. In Aim 2, we will investigate the reciprocal impact of Schwann cell-derived exosomes on neuro-invasiveness of cancer cells. This is a novel concept since up-to-date, the majority of the studies has focused only on the role of the unidirectional exosomal transfer from tumor cells on the (neural) microenvironment. These data can provide a new perspective of the exosome-mediated invasive behaviour and will further assess the role of the tumor microenvironment on tumor progression in pancreatic cancer. Moreover, we plan to identify NI-promoting targets in Schwann cell-derived exosomes that can be targeted to inhibit the activation and tumor-promoting effect in recipient PDAC cells. The results of Aim 1 and Aim 2 will help to identify potential diagnostic and predictive markers, which we plan to validate in a large cohort of patients with pancreatic cancer in Aim 3. These data would provide a novel approach to stratify patients into different risk categories and to improve the diagnosis for the early detection of recurrent PDAC.