Cancer cell-secreted eHsp90 binds and activates proteins in the tumor microenvironment crucial in cancer invasion. Therefore, targeting eHsp90 could inhibit invasion, preventing metastasis—the leading cause of cancer-related mortality. Previous eHsp90 studies have solely focused on its role in cancer invasion through the 2D basement membrane (BM), a form of extracellular matrix (ECM) that lines the epithelial compartment. However, its role in cancer invasion through the 3D Interstitial Matrix (IM), an ECM beyond the BM, remains unexplored. Using a Collagen-1 binding assay and second harmonic generation (SHG) imaging, we demonstrate that eHsp90 directly binds and aligns Collagen-1 fibers, the primary component of IM. Furthermore, we show that eHsp90 enhances Collagen-1 invasion of breast cancer cells in the Transwell assay. Using Hsp90 conformation mutants and inhibitors, we established that the Hsp90 dimer binds to Collagen-1 via its N-domain. We also demonstrated that while Collagen-1 binding and alignment are not influenced by Hsp90’s ATPase activity attributed to the N-domain, its open conformation is crucial for increasing Collagen-1 alignment and promoting breast cancer cell invasion. These findings unveil a novel role for eHsp90 in invasion through the IM and offer valuable mechanistic insights into potential therapeutic approaches for inhibiting Hsp90 to suppress invasion and metastasis.
癌细胞分泌的胞外热休克蛋白90（eHsp90）能够结合并激活肿瘤微环境中的关键蛋白，从而促进癌症侵袭。因此，靶向eHsp90可能抑制侵袭并防止转移——这是癌症相关死亡的主要原因。以往关于eHsp90的研究仅聚焦于其在二维基底膜（BM）介导的癌症侵袭中的作用，基底膜是衬覆上皮细胞区室的一种细胞外基质（ECM）。然而，eHsp90在三维间质基质（IM）——即基底膜之外的ECM——介导的癌症侵袭中的作用尚未被探索。通过胶原蛋白-1结合实验和二次谐波成像技术，我们证明eHsp90能够直接结合并排列胶原蛋白-1纤维，后者是间质基质的主要成分。此外，我们在Transwell实验中证实eHsp90增强了乳腺癌细胞对胶原蛋白-1的侵袭能力。利用Hsp90构象突变体和抑制剂，我们确定了Hsp90二聚体通过其N端结构域与胶原蛋白-1结合。我们还证明，虽然胶原蛋白-1的结合与排列不受Hsp90 N端结构域ATP酶活性的影响，但其开放构象对于增强胶原蛋白-1排列和促进乳腺癌细胞侵袭至关重要。这些发现揭示了eHsp90在间质基质侵袭中的新作用，并为通过抑制Hsp90来阻断侵袭和转移的潜在治疗策略提供了重要的机制见解。
Extracellular Hsp90 Binds to and Aligns Collagen-1 to Enhance Breast Cancer Cell Invasiveness
肿瘤(癌症)患者之家