Epidermal Growth Factor Receptor (EGFR) is a known promoter of tumor progression and is overexpressed in lung cancers. Growth factor receptors (including EGFR) are known to interact with extracellular matrix (ECM) proteins, which regulate their activation and function. Fibulin-1 (FBLN1) is a major component of the ECM in lung tissue, and its levels are known to be downregulated in non-small cell lung cancers (NSCLC). To test the possible role FBLN1 isoforms could have in regulating EGFR signaling and function in lung cancer, we performed siRNA mediated knockdown of FBLN1C and FBLN1D in NSCLC Calu-1 cells. Their loss significantly increased basal (with serum) and EGF (Epidermal Growth Factor) mediated EGFR activation without affecting net EGFR levels. Overexpression of FBLN1C and FBLN1D also inhibits EGFR activation confirming their regulatory crosstalk. Loss of FBLN1C and FBLN1D promotes EGFR-dependent cell migration, inhibited upon Erlotinib treatment. Mechanistically, both FBLN1 isoforms interact with EGFR, their association not dependent on its activation. Notably, cell-derived matrix (CDM) enriched FBLN1 binds EGFR. Calu-1 cells plated on CDM derived from FBLN1C and FBLN1D knockdown cells show a significant increase in EGF mediated EGFR activation. This promotes cell adhesion and spreading with active EGFR enriched at membrane ruffles. Both adhesion and spreading on CDMs is significantly reduced by Erlotinib treatment. Together, these findings show FBLN1C/1D, as part of the ECM, can bind and regulate EGFR activation and function in NSCLC Calu-1 cells. They further highlight the role tumor ECM composition could have in influencing EGFR dependent lung cancers.

表皮生长因子受体（EGFR）是已知的肿瘤进展促进剂，在肺癌中过表达。已知生长因子受体（包括EGFR）可与细胞外基质（ECM）蛋白相互作用，从而调节其激活和功能。Fibulin-1（FBLN1）是肺组织中ECM的主要成分，已知其水平在非小细胞肺癌（NSCLC）中被下调。为了测试FBLN1亚型在调节EGFR信号传导和肺癌中可能发挥的作用，我们在NSCLC Calu-1细胞中进行了siRNA介导的FBLN1C和FBLN1D的敲低。它们的损失显着增加了基础（含血清）和EGF（表皮生长因子）介导的EGFR激活，而不影响EGFR的净含量。FBLN1C和FBLN1D的过表达也抑制了EGFR的激活，从而证实了它们的调节性串扰。FBLN1C和FBLN1D的缺失促进了EGFR依赖的细胞迁移，在厄洛替尼治疗后受到抑制。从机理上讲，两种FBLN1亚型均与EGFR相互作用，它们的缔合不依赖于其激活。值得注意的是，富含细胞衍生基质（CDM）的FBLN1与EGFR结合。镀在衍生自FBLN1C和FBLN1D敲低细胞的CDM上的Calu-1细胞显示EGF介导的EGFR激活显着增加。这促进了细胞粘附并通过富集在膜褶上的活性EGFR扩散。厄洛替尼治疗可显着减少CDM上的粘附和扩散。总之，这些发现表明FBLN1C / 1D作为ECM的一部分，可以结合并调节NSCLC Calu-1细胞中的EGFR激活和功能。