Disruption of pancreatic stellate cell myofibroblast phenotype promotes pancreatic tumour invasion.. Disruption of pancreatic stellate cell myofibroblast phenotype promotes pancreatic tumour invasion.

In pancreatic ductal adenocarcinoma (PDAC), differentiation of pancreatic stellate cells (PSCs) into myofibroblast-like cancer-associated fibroblasts (CAFs) promotes fibrotic, therapy-resistant tumours. Conversely, suppression of CAFs can result in aggressive metastatic tumours. Here we show that the Rho-effector kinase protein kinase N2 (PKN2) is critical for PSC myofibroblast differentiation. Loss of PKN2 was associated with reduced PSC proliferation and contractility, retention of lipid droplets and decreased a-SMA stress fibres. PKN2 loss was also associated with a myofibroblast CAF to -like inflammatory CAF switch in the PSC matrisome signature both in vitro and in vivo. In spheroid co-cultures with PDAC cells, loss of PKN2 prevented PSC invasion but, counter-intuitively, promoted invasive cancer cell outgrowth. Further, deletion of PKN2 in the pancreatic stroma induced more locally invasive, orthotopic pancreatic tumours. Finally, we demonstrated that a PKN2KO PKN2 KO matrisome signature predicts poor outcome in pancreatic and other solid human cancers. Our data indicate that suppressing PSC myofibroblast differentiation function can limit important stromal tumour suppressive mechanisms, while promoting a switch to a cancer-supporting CAF phenotype. Overall design: mRNA profiles of 6 stromal-PKN2 knockout (KO) and 5 stromal-PKN2 wild type (WT) mouse orthotopic pancreatic tumours.

在胰腺导管腺癌（pancreatic ductal adenocarcinoma, PDAC）中，胰腺星状细胞（pancreatic stellate cells, PSCs）分化为肌成纤维细胞样癌症相关成纤维细胞（myofibroblast-like cancer-associated fibroblasts, CAFs）的过程，会促进形成纤维化且治疗抵抗性的肿瘤。反之，抑制癌症相关成纤维细胞则可能引发侵袭性转移性肿瘤。本研究证实，Rho效应激酶蛋白激酶N2（Rho-effector kinase protein kinase N2, PKN2）对胰腺星状细胞向肌成纤维细胞的分化至关重要。敲除PKN2会减弱胰腺星状细胞的增殖与收缩能力，导致脂滴留存，并减少α-平滑肌肌动蛋白（α-smooth muscle actin, α-SMA）应力纤维的形成。无论是体外还是体内实验中，胰腺星状细胞的细胞外基质组（matrisome）特征均显示，PKN2缺失会引发肌成纤维细胞样癌症相关成纤维细胞向炎症型癌症相关成纤维细胞的表型转化。在与胰腺导管腺癌细胞的三维球体共培养体系中，PKN2缺失不仅会阻断胰腺星状细胞的侵袭，还会出乎意料地促进癌细胞的侵袭性向外生长。进一步研究发现，在胰腺基质中敲除PKN2会诱导出更具局部侵袭性的原位胰腺肿瘤。最后，本研究证实，携带PKN2基因敲除（knockout, KO）特征的细胞外基质组谱，可预测胰腺癌及其他实体人类肿瘤的不良预后。我们的研究数据表明，抑制胰腺星状细胞的肌成纤维细胞分化功能，虽会限制重要的基质肿瘤抑制机制，却会促使癌症相关成纤维细胞向支持肿瘤发展的表型转化。
实验设计概述：本研究对6株基质PKN2基因敲除（knockout, KO）小鼠原位胰腺肿瘤与5株基质PKN2野生型（wild type, WT）小鼠原位胰腺肿瘤的mRNA表达谱进行了检测。