Proteolysis in close vicinity of tumor cells is a hallmark of cancer invasion and metastasis. We show here that mouse mammary tumor virus-polyoma middle T antigen (PyMT) transgenic mice deficient for the cysteine protease cathepsin B (CTSB) exhibited a significantly delayed onset and reduced growth rate of mammary cancers compared with wild-type PyMT mice. with PyMT;ctsb +/+ cells, was used to address the role of stroma-derived CTSB in lung metastasis formation. Notably, ctsb À/À mice showed reduced number and volume of lung colonies, and infiltrating macrophages showed a strongly up-regulated expression of CTSB within metastatic cell populations. These results indicate that both cancer cellderived and stroma cell-derived (i.e., macrophages) CTSB plays an important role in tumor progression and metastasis.

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Abstract. In recent years, researches have paid much attention to the physical, chemical, biophysical and biochemical properties of a cell surface. It is known that most of the cells' surfaces are charged. This charge depends on the biochemical structure of the cell membranes. Therefore, measurement of a cell surface charge is a significant criterion that gives information about the cell surface. Evaluation of the cells zeta-potential is important to understand the interaction mechanisms of various drugs, antibiotics, as well as the interaction of nanoparticles with the cell surface. In this study, we use the dynamic light scattering method to detect the zeta-potential change of Neuro-2a tumor cells. It has been observed that zeta-potential shifted to negative values after exposure to metal oxide nanoparticles and inducing apoptosis.