TGFbeta primes breast tumors for lung metastasis seeding through angiopoietin-like 4.
Cells released from primary tumors seed metastases to specific organs by a nonrandom process, implying the involvement of biologically selective mechanisms. Based on clinical, functional, and molecular evidence, we show that the cytokine TGFbeta in the breast tumor microenvironment primes cancer cells for metastasis to the lungs. Central to this process is the induction of angiopoietin-like 4 (ANGPTL4) by TGFbeta via the Smad signaling pathway. TGFbeta induction of Angptl4 in cancer cells that are about to enter the circulation enhances their subsequent retention in the lungs, but not in the bone. Tumor cell-derived Angptl4 disrupts vascular endothelial cell-cell junctions, increases the permeability of lung capillaries, and facilitates the trans-endothelial passage of tumor cells. These results suggest a mechanism for metastasis whereby a cytokine in the primary tumor microenvironment induces the expression of another cytokine in departing tumor cells, empowering these cells to disrupt lung capillary walls and seed pulmonary metastases.
Pubmed ID: 18394990 RIS Download
Angiopoietins | Animals | Breast Neoplasms | Cell Line, Tumor | Cell Movement | Endothelial Cells | Female | Gene Expression Profiling | Humans | Intercellular Junctions | Intercellular Signaling Peptides and Proteins | Lung Neoplasms | Mice | Mice, Inbred NOD | Mice, SCID | Neoplasm Transplantation | Neoplasms, Experimental | Oligonucleotide Array Sequence Analysis | Signal Transduction | Transforming Growth Factor beta | Transplantation, Heterologous | Tumor Cells, Cultured