Novel Quantitation of Autocrine/Paracrine Stimulation of Cell Motility in Vitro and Metastasis

摘要

Three established human breast cancer cell lines were analyzed and found to express the L1 adhesion/recognition molecule by immunofluorescence, RT- PCR, and western blotting. Protein expression levels correlated to their known metastatic abilities. Cells released a large soluble proteolytic L1 fragment and tiny L1-containing vesicles into culture media. Breast cancer cells express multiple integrin cell surface receptors that can bind to the released or shed L1. L1 proteolysis can be upregulated by a phorbol ester, indicating that this phenomenon can be modulated. A L1-shRNA retroviral vector was found that attenuated expression of breast cancer cells, and 3 retroviral vectors were constructed that cause expression of different length L1 ectodomain fragments. The chick embryo was found to be a sensitive system for studying breast cancer metastasis by using as few as 5,000 cells injected into the blood stream followed by recovery and culture of cells from the brain.