Cannon Austin R, Owen Meredith K, Guerrero Michael S, Kerber Michael L, Goicoechea Silvia M, Hemstreet Kathryn C, Klazynski Brian, Hollyfield Johnathan, Chang Emily H, Hwang Rosa F, Otey Carol A, Kim Hong Jin
Department of Cell Biology and Physiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Cytoskeleton (Hoboken). 2015 Aug;72(8):402-11. doi: 10.1002/cm.21239. Epub 2015 Sep 3.
The stroma surrounding solid tumors contributes in complex ways to tumor progression. Cancer-associated fibroblasts (CAFs) are the predominant cell type in the tumor stroma. Previous studies have shown that the actin-binding protein palladin is highly expressed in the stroma of pancreas tumors, but the interpretation of these results is complicated by the fact that palladin exists as multiple isoforms. In the current study, the expression and localization of palladin isoform 4 was examined in normal specimens and adenocarcinomas of human pancreas, lung, colon, and stomach samples. Immunohistochemistry with isoform-selective antibodies revealed that expression of palladin isoform 4 was higher in adenocarcinomas versus normal tissues, and highest in CAFs. Immunohistochemistry staining revealed that palladin was present in both the cytoplasm and the nucleus of CAFs, and this was confirmed using immunofluorescence staining and subcellular fractionation of a pancreatic CAF cell line. To investigate the functional significance of nuclear palladin, RNA Seq analysis of palladin knockdown CAFs versus control CAFs was performed, and the results showed that palladin regulates the expression of genes involved in the biosynthesis and assembly of collagen, and organization of the extracellular matrix. These results suggested that palladin isoform 4 may play a conserved role in establishing the phenotype of CAFs in multiple tumor types.
实体瘤周围的基质以复杂的方式促进肿瘤进展。癌症相关成纤维细胞（CAF）是肿瘤基质中的主要细胞类型。先前的研究表明，肌动蛋白结合蛋白帕拉丁在胰腺肿瘤基质中高度表达，但由于帕拉丁存在多种异构体，这些结果的解读变得复杂。在本研究中，检测了帕拉丁异构体4在人胰腺、肺、结肠和胃样本的正常标本及腺癌中的表达和定位。使用异构体选择性抗体进行免疫组织化学分析显示，与正常组织相比，帕拉丁异构体4在腺癌中的表达更高，在CAF中表达最高。免疫组织化学染色显示，帕拉丁存在于CAF的细胞质和细胞核中，这通过免疫荧光染色和胰腺CAF细胞系的亚细胞分级分离得到证实。为了研究细胞核帕拉丁的功能意义，对敲低帕拉丁的CAF与对照CAF进行了RNA测序分析，结果表明帕拉丁调节参与胶原蛋白生物合成和组装以及细胞外基质组织的基因表达。这些结果表明，帕拉丁异构体4可能在多种肿瘤类型中CAF表型的形成中发挥保守作用。
