Loss of TRPV4 reduces pancreatic cancer growth and metastasis

Pancreatic ductal adenocarcinoma (PDAC) is a rapidly metastasizing cancer characterized by a dense desmoplastic stroma made up of extracellular matrix (ECM) proteins, which complicates treatment. Upon stimulation, pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that are the source of ECM and cytokines in PDAC. We previously reported that mechanical stress activates PSCs and induces fibrosis through mechanical ion channel Piezo1-mediated TRPV4 channel activation, but its role in PDAC remains unclear. Here we report that pathological activation of Piezo1 differentiates human PSCs into an inflammatory CAF phenotype that expresses chemoresistance and cancer stemness markers CD10 and GPR77. In an orthotopic PDAC model, TRPV4 knockout mice exhibit a significant reduction in tumor size, circulating inflammatory cytokines, tissue inhibitor of metalloproteinases-1 (TIMP1), and pre-metastatic niche markers, serum amyloid A (SAA) proteins. A similar trend is observed in mice lacking functional Piezo1 in PSCs. The livers of TRPV4 knockout mice exhibit fewer cancer cell microlesions, lack macro tumors, produce lower levels of inflammatory protein S100A8, and develop fewer inflammatory cell clusters. In orthotopic and genetically engineered models of PDAC, these mice also have improved survival, suggesting that blocking TRPV4 channels may be a promising therapeutic target for PDAC. RNA seq profiling of livers from WT and TRPV4 KO or WT treated with the GSK2193874 TRPV4 antogonist in a murine orthotopic model of PDAC. RNA seq profiling of mouse pancreatic stellate cells activatated by the PIEZO1 agonist Yoda1.

胰腺导管腺癌（Pancreatic ductal adenocarcinoma, PDAC）是一种转移迅速的癌症，其特征为存在由细胞外基质（extracellular matrix, ECM）蛋白构成的致密促结缔组织增生性间质，这一病理特征极大地复杂化了临床治疗方案的制定。当受到刺激时，胰腺星状细胞（pancreatic stellate cells, PSCs）会分化为癌症相关成纤维细胞（cancer-associated fibroblasts, CAFs），后者是PDAC微环境中细胞外基质与细胞因子的主要来源。我们此前的研究表明，机械应力可通过机械性离子通道Piezo1介导的TRPV4通道激活来诱导胰腺星状细胞活化并引发纤维化，但其在PDAC中的具体作用仍未明确。本研究证实，Piezo1的病理性激活可将人类胰腺星状细胞分化为炎症型癌症相关成纤维细胞表型，该表型可表达化疗耐药及癌症干细胞标志物CD10与GPR77。在原位PDAC小鼠模型中，TRPV4基因敲除小鼠的肿瘤体积、循环炎症细胞因子水平、基质金属蛋白酶组织抑制剂-1（tissue inhibitor of metalloproteinases-1, TIMP1）以及转移前微环境标志物血清淀粉样蛋白A（serum amyloid A, SAA）家族蛋白的表达量均显著降低。在胰腺星状细胞中功能缺失Piezo1的小鼠模型中，也观察到了一致的实验趋势。TRPV4基因敲除小鼠的肝脏组织中，癌细胞微病灶数量更少，未出现大体肿瘤，炎症蛋白S100A8的表达水平更低，且炎性细胞簇的形成显著减少。在原位及基因工程改造的PDAC小鼠模型中，此类小鼠的生存期均得到显著改善，这提示阻断TRPV4通道或可成为PDAC颇具前景的治疗靶点。本研究还对小鼠原位PDAC模型中野生型小鼠、TRPV4敲除小鼠，以及经TRPV4拮抗剂GSK2193874处理的野生型小鼠的肝脏组织进行了RNA测序（RNA-seq）分析；同时对经Piezo1激动剂Yoda1激活的小鼠胰腺星状细胞开展了RNA测序分析。