Effect of Cathepsin L exposure on endothelial cell transcriptomics

Cathepsin L is a lysosomal protease that is secreted by several cancer cells. Cathepsin L upregulation has been widely associated with poor clinical outcome and increased metastatic incidence. However, whether Cathepsin L participates in tumor angiogenesis remains less studied. Our study showed a significant activation of angiogenic capacity of endothelial cells in presence of purified or tumor derived Cathepsin L. In addition, Cathepsin L exposure led to a significant increase in the proliferative capacity of endothelial cells. While the ability of Cathepsin L to promote endothelial cell sprouting, migration, invasion and tube formation can be attributed to its proteolytic effects on extracellular matrix, how it promotes endothelial cell proliferation remains obscure. The objective of this study was to test if Cathepsin L exposure can activate signaling cascades and gene expression leading to proliferation of endothelial cells. Human microvascular endothelial cells were exposed to 10 ng/ml of purified human Cathepsin L. 4hr later, cells were lysed and gene expression was measured using Affymetrix HTA 2.0 Transcriptome Array.