Extracellular HSP90α-LRP1 Signaling Promote Pancreatic Cancer Metastasis and Chemoresistance Via Regulating Epithelial-To-Mesenchymal Transition
Abstract Extracellular heat shock protein 90α (HSP90α) has been reported to promote cancer cell invasion and migration. However, whether pancreatic cancer (PC) cells expressed membrane-bound or secreted HSP90α and its underlying mechanism for PC progression were still unclear. Our study pointed out that highly invasive Capan2 cells has a higher level of secreted HSP90α, rather than membrane HSP90α, compared with those of less invasive PL45 cells. The conditioned medium of Capan2 cells or recombinant HSP90α protein was able to stimulate the migration and invasion of PL45 or capan2 cells, which could be prevented by a neutralizing anti-HSP90α antibody. Furthermore, secreted HSP90α promoted elements of epithelial-mesenchymal transition (EMT) in PL45 cells, including increases in vimentin and snail expressions, decreases in E-cadherin expression and changes in cell shape towards a mesenchymal phenotype, but these phenomena were reversed by anti-HSP90α antibody in Capan2 cells. In addition, high levels of low-density lipoprotein receptor-related protein 1 (LRP1) mRNA were associated with worsened patient survival in pancreatic adenocarcinoma. LRP1 as a receptor of eHSP90α for its stimulatory role of PC cells EMT and metastasis by activating AKT signaling. Down-regulation of LRP1 could promote chemosensitivity to gemcitabine and doxorubicin, but not to topotecan and paclitaxel in Capan2 cells. Therefore, our study reveals a critical role of secreted HSP90α on EMT events and suggests blocking secreted HSP90α underlies an aspect of metastasis and chemoresistance.