Department of Internal Medicine I, Ulm University, D-89081 Ulm, Germany Department of Internal Medicine I, Martin-Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany Institute for Cell Biology and Immunology, University of Stuttgart, D-70569 Stuttgart, Germany.
Mol Biol Cell. 2014 Feb;25(3):324-36. doi: 10.1091/mbc.E13-06-0334. Epub 2013 Dec 11.
Pancreatic cancer cell invasion, metastasis, and angiogenesis are major challenges for the development of novel therapeutic strategies. Protein kinase D (PKD) isoforms are involved in controlling tumor cell motility, angiogenesis, and metastasis. In particular PKD2 expression is up-regulated in pancreatic cancer, whereas PKD1 expression is lowered. We report that both kinases control pancreatic cancer cell invasive properties in an isoform-specific manner. PKD2 enhances invasion in three-dimensional extracellular matrix (3D-ECM) cultures by stimulating expression and secretion of matrix metalloproteinases 7 and 9 (MMP7/9), by which MMP7 is likely to act upstream of MMP9. Knockdown of MMP7/9 blocks PKD2-mediated invasion in 3D-ECM assays and in vivo using tumors growing on chorioallantois membranes. Furthermore, MMP9 enhances PKD2-mediated tumor angiogenesis by releasing extracellular matrix-bound vascular endothelial growth factor A, increasing its bioavailability and angiogenesis. Of interest, specific knockdown of PKD1 in PKD2-expressing pancreatic cancer cells further enhanced the invasive properties in 3D-ECM systems by generating a high-motility phenotype. Loss of PKD1 thus may be beneficial for tumor cells to enhance their matrix-invading abilities. In conclusion, we define for the first time PKD1 and 2 isoform-selective effects on pancreatic cancer cell invasion and angiogenesis, in vitro and in vivo, addressing PKD isoform specificity as a major factor for future therapeutic strategies.
胰腺癌细胞的侵袭、转移和血管生成是开发新治疗策略的主要挑战。蛋白激酶 D（PKD）同工型参与控制肿瘤细胞的运动性、血管生成和转移。特别是 PKD2 在胰腺癌中表达上调，而 PKD1 的表达则降低。我们报告称，两种激酶以同工型特异性方式控制胰腺癌细胞的侵袭特性。PKD2 通过刺激基质金属蛋白酶 7 和 9（MMP7/9）的表达和分泌来增强在三维细胞外基质（3D-ECM）培养物中的侵袭能力，其中 MMP7 可能在 MMP9 上游发挥作用。MMP7/9 的敲低可阻断 3D-ECM 测定和在鸡胚尿囊膜上生长的肿瘤中的 PKD2 介导的侵袭。此外，MMP9 通过释放细胞外基质结合的血管内皮生长因子 A，增加其生物利用度和血管生成，从而增强 PKD2 介导的肿瘤血管生成。有趣的是，在表达 PKD2 的胰腺癌细胞中特异性敲低 PKD1 进一步增强了 3D-ECM 系统中的侵袭特性，产生了高迁移表型。因此，PKD1 的缺失可能有利于肿瘤细胞增强其基质侵袭能力。总之，我们首次定义了 PKD1 和 2 同工型对胰腺癌细胞侵袭和血管生成的体外和体内选择性影响，解决了 PKD 同工型特异性作为未来治疗策略的主要因素。
